S4 E8. We install an AMR500 supercharger on the Kubota diesel powered Honda Insight.

[@jake20479]

Diesels really dont require bov's/ dumps to atmosphere. i work as a diesel semi truck mechanic and they dont use them. boost at idle is not necessarily ideal per se but not the end of the world either. as long as your EGT's are stable, cylinder pressure is in safe range, and you have enough fuel its not a problem. Diesels LOVE extra oxygen.

[@what9418]

I got the feeling he wants to bleed off an excess of boost, not to blow off spikes or whatever it is called.

[@denisohbrien]

My BMW m57 makes a few psi of boost at idle it's not an issue imho, arguably it's desirable as your Increasing the compression ratio and giving more oxygen to boot. Will make for better emission at idle.

[@FarmAlarm]

I would say his ultimate fear is blowing a head gasket. Which would be anyone's concern with too much boost.

[@timothybayliss6680]

The only thing that can happen is if you really crank the boost is you end up too lean at idle and have a misfire. That's at the edge of what can happen but it is possible.

[@JazzbLu]

Timothybayliss6680, please refresh your knowledge on diesels. They can safely run very lean. 80:1 is ok for an air:fuel ratio.

[@GTkyle]

Don't fear the boost. I'd leave the pullies alone but only make fuel adjustments from this point forward to achieve whatever results you're after. But I am just a random guy from the Internet.

[@smokesandalloy9487]

If I'm thinking right, won't the boost be dependent mainly on RPM and not load for the s/c? So, the max boost could be checked revving while stationary, and it should actually drop some under load at the same RPM due to increased volume consumed by engine? All that to say that I think the boost will actually drop under load vs while parked, unlike a turbo, but I could be wrong.

[@GTkyle]

@@smokesandalloy9487 for the most part you're correct. This supercharger is positive displacement meaning it can only push X amount of CFM per rotor rotation, and an engine's cylinder can consume only Y amount of air per stroke. So once you're off idle with this diesel, boost should remain the same up to redline, barring things like cam overlap or something of that nature that probably doesnt apply here. So the 10 or 11psi we saw when he revved it should be the same up to redline, regardless of engine load. Boost is a waste value, a measurement of the air the engine cannot consume.

[@GTkyle]

@@bobirving6052 that makes sense, although I don't expect the dip to be drastic. Hopefully Jimbo will split screen boost to RPM and do a thorough pull though the rev range so we can see

[@bobirving6052]

@GTkyle At peak torque, intake manifold pressure should be it’s lowest. The supercharger should increase output almost linearly, but the intake’s inertial mechanism will get the air into the cylinders more efficiently at the sweet spot where you get most torque. Edit: I realized this theory is not true. The supercharger’s output can increase faster than the engine’s intake, depending on pulley size. So pressure could increase or decrease as rpm increases. There will just be a pressure drop around peak torque.

[@ProDigit80]

Boost could be a problem at higher rpms, one, for the afr, but more so two, for the skinny belt. You don't want that belt under too much tension.

[@vandersnickmcduffle7333]

Boost at idle is common on supercharged diesel engines. 15 years ago or so, I built a twin turbo + whipple 24V Cummins pickup. It made 8PSI at idle. The idle boost is a non-issue. If the boost while revving get's into an uncomforable zone, a pulley change is likely the best and easiest solution. If you can't figure out the crank situation, maybe you can change the pulley on the stupidcharger.

[@KRRZ350]

I think I've seen that truck. Was it white?

[@annonymous7440]

​@@KRRZ350 nah mate, it was red with hello kitty stickers all over. It also was rolling on thirteen inch gold Dayton's.

[@monolyth1999]

Send it! Blow-off valves are overrated.

[@juhomaki-petaja]

Gasoline engines need it

[@MyLonewolf25]

@@juhomaki-petajano they don’t

[@juhomaki-petaja]

@@MyLonewolf25 study some more and understand what is happening in blower gas engines...

[@Mrshotshell]

@@MyLonewolf25 Without a blow off or recirculation valve a positive displacement blower builds pressure in the charge pipe before the throttle body which will heat soak the blower and intercooler if it has one. source: my eaton m90 supercharged rx7

[@monolyth1999]

@@Mrshotshell heat soak?, pfff. 10psi is for rookies, and Jimbo is not a rookie.

[@FarmAlarm]

I hope *Future Jimbo* sees this. You should be able to get rid of the *Flutter* in the boost gauge needle by adding a type of inline restriction. Basically slowing the boost down to the gauge. This "should" work. Cool project.

[@Mrshotshell]

Also known as a gauge snubber, for easier researching

[@davismccoy77]

Yep, Optimal Welding did this when he turbo’d his welder and it fixed it

[@somedude2492]

​@@davismccoy77when he turbo'ed his what?

[@thriftyamerican5719]

I had success with a DIY dampener that was just a plug of loose cotton pulled from a Q tip and stuffed in the line behind the manual boost gauge.

[@CreeperOnYourHouse]

@@somedude2492 A lot of electric welders are essentially standalone generators with live wires you handle. This is to avoid needing to put in a heavy duty fuse in the building it's in. He turboed the generator for the welder.

[@fightfanian]

Install your intercooler. It will drop the boost a tiny bit and cool the charge, making it safer all around. Then SEND IT!

[@pjaenator]

Agreed. I am sure it would be the "Banks Power" recommendation as well.

[@almfreak]

my favorite part of the weekend! Thanks for the fun videos Jimbo!

[@robotcantina8957]

Glad you enjoy it!

[@johnnyzander1466]

Simple fix for the boost meter. Put a restrictor with a hole of approx 2 mm in the hose. It evens out the pressure fluctuations.

[@tanhelmet]

Note to Present Jimbo, please buy Future Jimbo a cool beverage. Your tenacity, attention to detail and knowledge is superlative.

[@hattyfarbuckle]

Its funny how being around the channel long enough makes unique statements sound normal "you may recall how I installed a stupidcharger on a twostoke leafblower motor and used it to power a.... "

[@dinosshed]

Awesome work as usual. Thanks for the entertainment. The gauge is fluttering with the pulse of the supercharger lobes and the intake valves. Roots blowers by design have a high and low output as the lobes cover the suction and discharge during each displacement event, similar to a workshop air compressor. To even out the pulse, the only option is to install a large plenum. This will absorb the fluctuations, but it's really not going to make a world of difference. These little kubota engines don't flow much air, so 10psi is showing you the restriction. If the engine had improved breathing, the pressure would drop. The other consideration is after adding an intercooler, the pressure will drop again once passed through the heat exchanger.

[@truckgotstuck]

I'm making this comment about 4 minutes in, so sorry if you cover it later in the video. This is how I equate it. The old saying "there is no replacement for displacement" still stands true in a sense. This is because by bosting engines, we are in effect increasing the amount of air and fuel that engine can displace into an engine on every intake stroke. The more fuel air/fuel we can et in, the more power we can get out. Turbocharging and supercharging are using devices that allow us to squeeze more bang into every revolution. Turbocharging and supercharging are how we increase the fuel displacement of an engine. What this has done to my thinking is changed how I calculate engines in my mind. A naturally aspirated engine us under the force of ambient barometric pressure, which is 14.7psi. 14.7psi 1 1 bar, or 1 atmosphere. If you have 21 atmospheres, you have double the volume of air in the same space. Metric makes so much more sense in this case. When you put 14.7psi of boost to an engine, you have the 14.7psi (1 atmosphere) from ambient pressure, and another one from the boost. You are doubling the volume of the air, and when air/fuel ratios are correct, you have double the air/fuel mixture. You are in in effect turning a 731cc diesel engine into a 1462cc engine that weighs less than a typical 1462cc engine. 14.7psi of with no adjustment for intake and exhaust restrictions, is doubling the power that can be generated from that air/fuel mixture charge. The difference is, you don't have the additional rotating mass and other factors that rob power in an engine that has a physical cylinder displacement of 1462cc. Boost makes engines have a higher displacement, but don't have a heavier engine mass that they have to rotate, and they don't have to carry that extra weight. With that, boosting an engine can be more efficient at generating power. You can calculate if it's more efficient by calculating the fuel consumption against the horsepower, and comparing the result of the naturally aspirated engine against the result of the boosted engine. I find this way of looking at engines helps me wrap my head around the expected torque and horsepower values. It makes more sense in my mind, I hope it maybe helps some other people visualize it too.

[@buggersunboxings4650]

For the lost gauge fluctuations. You can rip the cotton off a cotton swab. Jam it in the line close to your gauge. Not block it but put a decent amount in. Helps with the flutter.

[@turnip5359]

Is this a permafix or just a bodge job?

[@sargehoffhines4630]

From my experience Kabota (well, most manufacturers of) diesels have sturdy block and head construction and I’d keep a close eye on the EGTs since heat will likely destroy the engine before cylinder pressure will. Oh and I guessed 5psi at idle but the was just a guess based off your comment after squeezing the charge pipe. No math, just lucky lol.

[@goosenotmaverick1156]

My understanding is egts and cylinder head temps are the point where when they get too hot they like to drop valve seats. But beyond that I've seen plenty of em with thousands of hours of abuse, I assume it would be fine for quite some time if pushed a little

[@PopsHowTo]

Man! These big budget shows always leave you on the edge of your seat wanting more! That’s how they keep you coming back! I was not expecting 6 psi at idle. But I also don’t know much about superchargers either. Can’t wait for the test drive!

[@Platypus_Warrior]

Hi Robot. I should have said that long ago: I had this silly challenge when I was younger of making as much distance as possible with a stock old 206 peugeot with a 1.4l HDI motor. I did 1300km with 45liters of fuel. For conversion that's like 68 mpg, the car already had 125 000km on it at the time (or 77 700 miles) the tires were over inflated and it was a company car so no backseat. The car was from 2003 maybe I was a bit reckless at times to brake as little as possible and accelerating slowly.

[@marco23p]

I got 1200 km's from the south of France to Luxembourg (where fuel is cheap ;)), with the same car model and engine. We took the all toll-free road, so a lot of 80 km/h driving with a hot engine, which turned out to be very efficient. No modifications to the car were needed.

[@GoldenCroc]

This, as a fuel consumption number aficionado, is the kind of story I like to hear. Well done. Most small-ish diesel cars can get about 3.5l/100km when driven at their most economical speed on favorable roads. I have never owned such a small diesel car to be involved in pushing for great numbers, though I have driven my larger cars quite a bit under their "extra-urban" EU fuel rating.

[@Will-sc3hw]

my 1.4L D-4d toyota gets approx 72mpg so 68 on a 1.6L is solid

[@fericyde]

I have no idea what you should do. Jimbo, but I can tell you that you are my hero. Really enjoy the series

[@kolyakabmx]

Don't worry about excessive boost. Just keep your fuel on the level you want to and extra air will give you less smoke.

[@ProDigit80]

Aside from afr, he needs to make sure the skinny belt doesn't get under too much tension.

[@evil_me]

Banks "lockjaw" build is a Whipple supercharged duramax so it's a bit similar. They had to run a bypass valve for idle because it was building up way too much heat. Any time you have pressure in the intake work is being done to compress the air and adding heat.

[@kd5inm]

Wouldn't an intercooler fix a bunch of that?

[@nicolasdeleon2819]

​@@kd5inm The intercooler would cool the intake charge going into the engine, but it wouldn't stop the supercharger from overheating. In fact the added restriction woukd exacerbate the problem at idle/low load. He could try water injection pre-supercharger. But, he would be better off reducing the output of the supercharger. Or bypassing excess air to keep the supercharger from overheating due to the excess pressure/restriction at idle.

[@jjsledneck]

It’s probably not a problem. He’s been having trouble building enough heat to get the engine up to operating temperature.

[@nicolasdeleon2819]

@@jjsledneck Sure the water temperature, but the temperature of the supercharger itself may become a problem, especially if it continues to make more boost (due to the lack of flow) through the rev range. Without a Compressor Map we dont know how far outside its efficiency range it would be. It might see 15+ psi at higher rpm without making changes.

[@thatcheapguy525]

this channel consistently does the things I've dreamed of but no longer have the health to do myself. its fantastic to watch!

[@YourScaryMother]

What most people don't understand is that boost is a measure of restriction. If you have a turbo or supercharger that is producing 8 lbs of boost, then you change the heads, intake, or anything else in the system, your boost will likely not be the same after, because you are changing the amount of air in/out in some way. If your boost drops, that is because it is better flowing, and you can then change your pulley to increase it back up to your previous amount, basically increasing the overall power at the "same" boost level

[@MiniLuv-1984]

Jimbo, I am sure, will heed your comment - its looking at the issue from another perpective and that usually produces a deeper understanding and better solutions.

[@Sevalecan]

Your boost can also drop simply by adding an intercooler which will reduce the air pressure while increasing the manifold air density and power. The restriction isn't the only factor in that number. Banks goes on and on about manifold air density, and it makes a lot of sense.

[@YourScaryMother]

@@Sevalecan Obviously, there are other factors than *just* restriction, but it is the largest one. I was keeping it simple. There are engine builders on KZbin you can learn more about it from them. Steve Morris or Pete Harrell for example have some good videos on it, that cover quite a bit about turbo & supercharger builds

[@sasabarisic8864]

Exaxctly! Up to a limit, and that's usually the mass flow limit of the compressor, no matter if it's a supercharger or a turbocharger. On a crappy flowing 2.0L engine, one compressor may produce 1 bar of boost and not heat up, while on another 2.0 properly flowing engine, it may barely produce 0.5 bar of boost and heat up.

[@Brianlikescars]

As a big horsepower overcompensating track rat… God I just LOVE everything this channel stands for.

[@steelwheels327]

I think your work is very impressive , heck i figured you were a mechanical engineer. i love these projects

[@metallicrockb1]

I'd leave the boost as is. Maybe put an intake temp sensor in there to see if you need an intercooler. The gauge moving around was from the intake valves closing, BTW. Keep up the great work. This is fascinating. I used to work on these diesel generators all the time, in large light-alls. I always wondered what it would be like in a go cart or something.

[@Ultimatebubs]

I'm one of your less technical KZbin channel followers, so I'm going to have to give you the "Send it as is, YOLO!" response that you're probably not looking for. But, seriously, it's time to embrace your inner Cleetus McFarland. Give it ALL the boost, if it blows, it blows!

[@Engiction]

Since he got another engine 😂

[@goosenotmaverick1156]

As much as I want him to Do it for Dale, ole Cleet has a budget to work with, that a lot of folks don't. A replacement d722 last I seen for a decent unit was at least a couple grand.

[@lagmonster7789]

@@goosenotmaverick1156 Good point, it'd be different if we could donate/join a channel membership to support some crazier projects.

[@randr10]

Believe it or not these Kubota diesels are a lot more expensive than a junk yard 5.3. Like many multiples we're talking.

[@goosenotmaverick1156]

For context I just found a new reman unit for sale in Texas for $4500.

[@newtome-jessegates6310]

so glad this channel exists, this is the kinda stuff id like to be goofing around with if i had the means

[@jean-charlesweyland129]

At last, the Mazda 626 Comprex has finally got a spiritual offspring ^^

[@kansasadventure1831]

Like the profile picture

[@jean-charlesweyland129]

@@kansasadventure1831 Thanks, it's the cover of Iron Butterfly's first LP "Heavy" released 4 months before In A Gadda Da Vida.

[@TSRGarage]

Sunday morning is now complete. The experiments are the best part, I am not addicted to Robot Cantina at all....☕️. Now that I have watched another great episode, I can head out to the shop and work on my project. Great work. Waiting (patiently) for the test drive.

[@LintLoaf01]

A lot of older cars and trucks that used v-belts and had a bunch of accessories that need belt drive often had two pulleys on one or more of those accessories. That way you had one belt with good engagement on the crank and one drive pulley, then another belt drives another accessory off of the first one, ensuring positive belt engagement for all drive pulleys, and no need for idlers pushing the v-belts in the wrong direction. As for the boost at idle, I don't know if a blow off is really necessary being that it's a diesel, but it may be possible to electronically actuate one using something simple like a switch on the gas pedal.

[@legros731]

A blow off would be more to protect the supercharged than the engine lot of heat at idle making that much boost The engine seem to be a big restriction for the supercharged and the reason the boost is so high at idle More restrictions equal more boost at the same air volume The original Subaru engine may be the same 660cc size but is clearly way more efficient/less restrictive And make 3x as much as this 20 HP engine

[@Cinnamonservices]

Jim- I think a useful metric for this process would be a thermocouple placed after the charger. You get a really effective cooling and atomization effect from the gasoline on the carburetor application, but superchargers make a ton of heat themselves, even before the heat gain from compression. With no evaporative cooling on the diesel, I'd theorize you're getting a decent amount of boost only from expansion, but the actual density of the charge is far from that of ambient air at ambient temperatures. I think you're seeing at least 60 degrees of temp rise between ambient and after the charger, so that shoud account for roughly 2psig by itself. Venting would disproportionately reduce your efficency, as you're still paying the price to compress and heat the air, to then dump it overboard. Solutions may include an aftercooler, water meth, and reducing the drive speed of the charger to better match the air requirements of the engine. I recommend caution going above 10psi on this, as factory turbo kubotas dont run much more pressure than that sustained, and those are built for it. So, how are you going to get that 10psig to be as cold and dense as possible?

[@bigcheese781]

With a 1:1 ratio you'd have about 5.1 lb of boost with that setup (at speed). Expect around 3lb at low speed due to the additional parasitic blowby. Back-calculating I'd say you are currently running a 1:1.25 overdrive ratio. Needle bouncing is expected since the plenum chamber volume is quite low in your setup. Did a lot of these calculations when I put an Eaton M45 on my 800cc Suzuki, also ethanol efi. Let me know if you want numbers done. 👍

[@SoLSamuraibloodblade]

With the drive belt I would look to see if there was one in the same size for running lawnmower blades. Those are v-belts and they run on the back side of the idler. The idler pulley does also have flanges to keep from throwing the belt off.

[@WarrenGarabrandt]

I have no idea if that pressure is safe or not, but I'm fascinated to see how this project progresses. Great job on everything you've done so far! Thanks for bringing us along on this journey!

[@greggc8088]

Queen said it best- "Pressure pushin' down on me Pressin' down on you, no man ask for Under pressure that brings a building down Splits a family in two, puts people on streets Mm-ba-ba-beh, mm-ba-ba-beh Dee-day-da, ee-day-da That's okay" Send the pressure and don't worry about the family of parts getting split in two. it's OK.

[@NotSoGrandGarage]

If it's a concern... I'd swap the pulley on the supercharger for something a little larger... But as long as blower rpm is in the safe limits for the unit, I wouldn't worry about it. As you said.. diesels are controlled by fuel.. not air. Can't have too much air... Only too little. Cylinder pressure is created by fuel and timing. The little bit of pressure added to the cylinder by the supercharger won't hurt anything... even at idle.

[@hackitgarage6503]

I love how you clarify the reasoning of why you choose to do things the way you do and make your future intent on improving the hardware clear .. Your videos are exactly the type of content that interest me and every time I watch one I get closer to buying a lathe

[@acurarl9929]

Next step is to test drive as is and then do an intercooler. No need to turn boost down. Motor can handle it. Absolute worse case is you nip the head gasket but honestly if was me I’d absolutely test drive it. I build Harley motors daily so diesels are not my wheel house but I still understand enough about engines to know you have very little risk here. A head gasket is a small price. If you do nip a head gasket just know one thing do not try to start the engine after you shut it off or high risk of bending a connecting rod. Other then that. Watch your EGTS and let er eat

[@saltycanadian6190]

Keep it around 14.5 psi for the stock block. Then pull the crank bearings after a few test drives. Soft and hard driving. Check the clearances, and then check the head for any damage. If it’s all still within spec, add some slightly bigger injectors. 100-150cc larger, and keep the boost at the same level. Fuel is a great way to keep the engine cool under boost.

[@nerd1000ify]

Spark ignition runs cooler when it's richer, the opposite is true for diesels.

[@Bigshooterist]

My favorite episodes are adding the boost. Here we go. Great job, as always. 😎👍🏼

[@carpespasm]

Do they make high volume whoopee cushions that actuate at a calibrated 15psi? That could be a good way of venting excess boost. Maybe back-bending a single-v belt is worse for it than a poly-v belt, but I've worked on everything from Pontiacs to elliptical machines that regularly have very tight bends on poly-v belts and it never seems to do them a lick of harm. As long as you're not loading the alternator so much it slips I expect the belt will hold up well enough for your purposes.

[@nerd1000ify]

Poly Vs don't mind it at all, it's just single V belts that prefer not to be bent backwards. Even then you can get V belts that are designed to handle it, in fact they even make double sided ones that fit V-pulleys on both sides.

[@Patshes]

Excellent video!!! Can't wait for the final results on this once everything is sorted.🆒😎💪!

[@thatcarguy1UZ]

My recommendation would be to try a 1:1 pulley ratio or even a slight underdrive. Also, maybe you can use that electric dump valve to vent boost at zero throttle using a normally closed switch that opens when the throttle is depressed.

[@Mrshotshell]

The only bad thing about making boost at idle on a diesel is the heat generated. On a gas engine it would be generating even more boost in the charge pipe before the throttle body

[@thatcarguy1UZ]

@@Mrshotshell agreed. I'm just thinking about during times when the engines idling and it's putting needless stress on the supercharger it might be beneficial to allow the engine to just idle it atmospheric pressure and vent the Boost that the compressor is making.

[@legros731]

The engine is a big restriction to the supercharger and why the boost is so high at idle The Subaru engine even if it's 660cc like the Kubota engine make 3x as much power so it way more efficient and less restrictions on the supercharger if the supercharger make 1000cc every rotation and the engine need 500cc the engine would be in boost vs a engine that need 2000cc of air would be in vacuum at idle With a 1:1 pulley you can see the second example would never make boost if the engine need 2000cc per rev and the supercharger give 1000cc per rev plus volumetric efficiency vary with rpm/engine design Root type supercharger are constant displacement and rated by how many liter per rev they displace Boost is complicated lol

[@iamarawn]

I'm really curious on the next step of the DIY brake booster system. If it works, I'm going to copy it for my project.

[@robotcantina8957]

We made a second video on the DIY brake booster system and we eliminated the chatter with a programmable delay relay. After shooting that video we found a compact programmable delay relay that completely simplifies the whole system. we will do another update soon.

[@sysdollarsystem]

If you could engineer a suitable leak you would reduce boost pressure, just not sure if you can engineer a precise enough and consistent leak. Maybe just add pinholes until you get the desired boost.

[@MarkSparks-xd9yy]

that thing is already running so fast there appeared to be doppler distortion around the license plate. 10 psi & you're going into orbit.

[@drewkossen9324]

I would't worry about the blow off valve unless you are trying to get all the mpgs. Props for acually describing the role of the blower in gm two cycle diesels (51,53,71,92,110[some of them],149,567,645)

[@someguy325es]

We used to use a lawn mower fuel filter on the hose going to MAP sensors to dampen air pulses

[@victorthecarguy3126]

Have a look at the Sporlan/Parker stepper motor regulator. "Electric Regulator Valve - CDS Series" You can get one and a control board that will take 4-20 mA for a control signal and a motor that will run on 12V. These are used in refrigeration. With one of these and you're control skills you can do whatever you want with the boost. There are mechanical options in the refrigeration world but they don't offer the easy to change capabilities electronics offer.

[@lukewilliams1188]

Hey Jimbo. The boost needle jumps with the pulsing of the supercharge/ intake opening and closing.. you can choke it with a little valve they use for fish tank bubblers and adjust it till it's relatively stable😊

[@iceman45ification1]

Wow that's way more boost than I expected too. Don't think it would hurt anything as diesels like to run lean. It would sure help keep the EGT's and soot down at the same time. All-in-all, I think it would work out fine. Hopefully, you can sneak the intercooler in somehow. Can't wait to see how she'll run. Nice work Jimbo!! 💪🔥

[@blumafuji2753]

If you still have the stock intake of the supercharger they are crap... hella restrictive, i don't know if it will really change something at your power level but yeah just let you know it! For reference we made 140hp on 1.3L micra here with this supercharger, not a lot but yeah it can pump

[@TopsieT]

What about an external waste gate? My thinking here is you can dump the excess boost at idle to atmosphere and have it controlled by a Arduino using a pressure sender, RPM and solenoid using vacuum from the vacuum pump? If you wanted to be really fly you could even throw a throttle position sensor in the mix!

[@toydoctor88]

I was thinking the electronic "roboot" throttle body from the saturn project. Use the throttle body to bypass the supercharger. Could be simple on/off based on throttle position, or fancy with a feedback loop and controlling boost.

[@olewesgarage3304]

Howdy Jimbo! I ain't an expert on this particular engine, but if you wanted the belt to have more contact with the alternator pulley, how about adding another idler pulley at the bolt where the turn buckles are?

[@MikeTheMechanic123]

The belt shouldn't be an issue, Dodge put a v belt with a similar idler on a 1976-1978 Plymouth Volare/Dodge Aspen Slant 6 AC system. So I converted my friend's slant 6 with a similar AC setup I made myself. To be fair, Chrysler DID change it by the time the car was done with in 1980.

[@golftdibrad]

Jimbo, awesome work. When I had my supercharged Miata (m45 and mp62) it had an internal bypass to 'unload' the blower under part load conditions. This was operated via a vacuum canister...which you can't do. For testing I'll echo everyone else and say the extra air won't hurt the engine. Over time it will negatively affect belt life, fuel economy, and blower life, probably in that order. Im sure you can design a bypass/dump to unload the blower based on throttle position to reverse those effects if you decide to keep this configuration. Yes I know you don't have TPS now, but you indicated that it will need to be added at some point for the fuel rack controller modifications. Cheers!

[@tonymunn]

I have nothing intelligent to add except, I love your videos. I am trying to tune my 1973 Toyota Corolla with the 3TC engine that's turbocgarged and runs on propane. You give me hope.

[@Skwisgar2322]

Banks Power has a series of videos that goes into great depth how supercharging a 4 stroke diesel works. Like SUPER depth like measuring combustion chamber pressure and in/out heat etc. It can work great, but you will want good intercooling.

[@peterelvery]

Hi Jimbo. As you probably know, the most numerous forced-induction 2-stroke diesels are the GM/EMD multi-cylinder units used in railway locomotives. These have an overhead camshaft actuating the fuel injector and 4 poppet exhaust valves instead of piston exhaust ports. Both exhaust scavenging AND intake air density are greatly improved.

[@noreverse1152]

You have an interesting situation, two positive displacement devices, engine and blower, butting heads. The manifold pressure is only function of rpm, independent of the load. That is, it will be increasing proportional with rpm no risk of runaway boost. Pressure will likely drop with the addition of an intercooler. For now I would install an EGT sensor and boost gauge and do some testing

[@GrEmLiN76X]

I highly recommend an AirLift type tool for servicing the cooling system. It’s a Venturi tool that runs off compressed shop air to draw a vacuum for leak checking / air removal, and then break the vacuum with coolant. Makes refilling the system with no air bubbles a VERY fast and easy process. I believe Harbor Freight sells a version of the tool now.

[@PCUser-m4u]

As others have pointed out, 6 psi at idle may not be a problem. You need to run and/or drive through the engine's operating range and see what peak boost looks like and then judge if it needs be controlled. I'm another random guy from the internet, and have no forced-induction experience. I do have decades of experience in building naturally aspirated 2 and 4 stroke engines (mostly for kart racing), and raced for 20 years myself. Racing vehicles being just a rolling physics experiment themselves, lessons were learned along the way. The primary lesson is - don't cure symptoms, cure problems. If it proves boost must be reduced do so by engineering a proper drive setup for the supercharger that optimizes the speed of the blower through a revised effective drive ratio. As you've pointed out in many of your videos compressors heat their output as a by-product of the compression process, so you don't want to run the blower too fast and then bleed of its output, even if it seems easier than implementing an engineered and sustainable accessory drive. You've proven the supercharger is viable in the application - you need to move directly to improving its implementation rather than spending time and effort band-aiding symptoms created by limitations of the current implementation.

[@SockyNoob]

God I love this project and channel so much. You deserve a Patreon or something. I keep recommending everybody into cars or mechanical stuff to come watch Jimbo over here. Really the peak of any Sunday. You're definitely no idiot honestly.

[@nicolasdeleon2819]

A small Electronic Throttle body tee'd into the boost hose before the manifold. You can ignore the dual TPS and just run the valve off of 12v PWM (or on/off). Only requires 2 pins on the TB. Basically a larger 12v dump valve that you can use to control boost. Or a mechanical solution is a 38mm ebay BOV (not a diaphragm style, the kind with a just a metal cylinder and a spring) You can adjust the springs to have it open at a certain boost pressure, and but have the top of the BOV referenced to boost. You can then control how much the BOV vents using a PWM solenoid to modify the boost reference to the BOV. Ive seen that used in turbo applications as well, in lieu of a wastegate on the exhaust side. Works very well. And the if the electronics fail, the spring will allows default to venting/low boost.

[@nicolasdeleon2819]

Thinking more on this, for basic testing/sizing, a cheap plumbing Ball valve would be a good manual way to determine how big a leak is needed to control boost. And then a more sophisticated/self regulating solution can be made afterwards.

[@alexjoyce1276]

I can't believe it's time!!!!! I have waited to see this for ages!!!!!

[@jeremykamel9655]

For boost control I’ve seen people use a radiator cap adapted inline on the inlet pipe. Then you select the radiator cap that works with the desired boost limit. It just pops off and dumps extra boost.

[@Spudz76]

I think a mini CVT drive for the stupidcharger so that it boosts low at idle but also can do 45psi at top speed. Variable drive ratios fix everything, and that belt isn't abused enough yet.

[@goldcountryruss7035]

A 3LX-460 cogged belt is uncommon but available online. The cogged version will work excellent in your application as back-flexing wouldn't be a problem. An electronic waste gate would work but for low capacity so would a big idle air motor. I generally use 1/2-20 threads for adding drain ports to pans because it is the most common size for older American vehicles. Many times, I have brazed on 1/2-20 hex nuts on a pan to create a new outlet. Then I have a standard size and can either use a bolt w/gasket or drain plug.

[@jacobcurzon420]

Absolutely love your videos. Watching them makes my day

[@robotcantina8957]

You are so kind

[@DigD97]

You could be the Tesla Gastown in a bad pandemic.. love these videos. Just because it has enough engineering and not too much. Not that I can’t understand too much but I like to relax when I watch the Internet.

[@timlocher4829]

You can use an external wastegate like a cheapo 38mm on the charge pipe to dump higher pressure. People will do that with overdrive superchargers brings the pressure in early but bleeds it off on the top end. You can control it by springs or a hobbs with a MAC valve. Both will work but like in a turbo setup just springs will creep open slowly while the Mac valve will hold till it reaches max which makes everything more responsive

[@robertscholz4486]

For my two cents ... if it were me, I would consider changing the supercharger pulley to slightly reduce boost (considering that you are already seeing 6PSI at idle). This would serve a two fold purpose: 1. it would allow you to use the dump valve that you already have in hand, and 2. you reduce the risk of over heating the supercharger -- over-boosting will overheat the intake air thus running a greater risk of detonation. A third reason, though ancillary, you bought the dump valve on the jungle site -- if it has a failure without mitigating the current boost level, you will likely be swapping to the spare motor that is on the stand!! Great episode!!

[@PaulThomas-qo9vy]

"run the risk of detonation". Isn't that a gasoline engine problem (detonation). This is a diesel Kubota, absolutely No risk of "detonation". There is No fuel in cylinder during the compression stroke to detonate! With boost at idle the diesel will simply burn cleaner & make more power.

[@robertscholz4486]

@@PaulThomas-qo9vyyou know, your right ... my bad ... slipped into gas engine in my head when thinking about the problem. Feeling dumb now ... Doh!!

[@ninelivesracing]

Things I learned about roots blowers. They are constantly making boost and that means heat. They pump in a ton of heat. Enough heat to make less power than running NA. Don’t cheap out on the intercooler. You’ll want a bypass valve to kill the boost at idle. This will help with the heat. Just set up a push switch that opens the valve. Have the switch replace your idle control screw.

[@knurlgnar24]

The boost looks near perfect for your application to me. Send it. Diesels don't need dump valves in a setup like this. You don't have to give it all the beans/fuel if you're uncomfortable with the cylinder pressures or EGT.

[@matman999999]

The suspense. KILLING ME !! DRIVE IT. Lol. pleESE.

[@ptonpc]

No advice, I'm just impressed as always.

[@drunkskunk00]

They make variable speed pullys, in the $120 range. Not cheap, but one might be useful for dialing in the right size and for the supercharger.

[@bobb.4807]

Actually, I wouldn’t worry too much about that idler that you added . Back idlers are commonly used on several automotive applications and have been for years so it’s nothing new and shouldn’t hurt the belt providing the Bell tension is tolerable.

[@Dan-vq4pz]

10:19- YES! THANK YOU!! My 4 year old and I giggle at it

[@chrisdeli7547]

there was competition dump valves positioned on the intake so the competitors will run the same pressure. it was actually a piston with a spring you can use a basic dump valve the same way put a 7-8 psi spring and if goes over it will "leak" since it cannot hord pressure and you adjust by adding sims or putting a softer spring.

[@adrienst.raymond6801]

Boost at idle is fine, I’d recommend pulling the cylinder head and replacing the stock head bolts with head studs but for testing purposes you should be fine. As for tuning; at idle, remove the boost hose and dial up the fuel screw until it smokes black slightly at idle. Then reconnect the boost hose and you should be roughly close to a correct air/fuel ratio. You can do the same thing under loaded conditions, turn up the fuel screw and go for a drive. If it smokes black at max boost, you’ve got too much fuel and should turn it down a touch. A pyrometer is highly recommended, as those aluminum pistons will begin to come apart at around 1200-1300 degrees (1221 degrees Fahrenheit specifically). I’m not sure if that engine is equipped with piston cooling jets. I don’t think it is. Either way, running boost does help keep exhaust gas temperatures lower and more controllable as the higher air flow cools the internals slightly quicker than running naturally aspirated. A charge air cooler will also help immensely with EGTs and more power. If you do decide to dial in the boost by tweaking the air/fuel ratio, do not be alarmed if you occasionally see white/gray smoke. That is not always an indicator of a failed head gasket. A coolant system pressure tester would be excellent for maintaining faith in a head gasket. White or gray smoke would be an indication of injection timing being slightly off. Recommend advancing the injection timing as needed by clocking the injection pump. If you begin burning up glow plugs, the injection timing is too retarded. Have fun!

[@jonahbuilds4107]

I have a mercedes om617 diesel, my suggestion is to keep an eye on egt temp, keep in consideration that less heat is kept in the manifold because you no longer have the backpressure from the turbo, but in all reality the only harm you are likely to do by overboosting is lifting the head or pushing an intake valve open, wich lifting the head is easy and relatively cheap to fix. If it was me id pressurize the intake until the valves let the pressure go, then shoot for a couple psi below that

[@joshuagibson2520]

I once had a side hole. Then my main hole found out. Didn't turn out well.

[@robotcantina8957]

lol... :)

[@Engineerd3d]

Diesel does not care that you’re putting in extra air. It won’t make any extra power until you add fuel. It’s possible that the leaner condition will increase efficiency. I would say test drive it and keep an eye on it.

[@Mad.Man.Marine]

Not sure why people insist on pointing out stuff they THINK is wrong when it takes a two second google search to see that in reality they are the ones that are wrong. It’s totally fine to use a tensioner on a v belt to have the belt bend backwards some. It’s been implemented on many designs in the past.

[@pixels2polygonss]

My only two concerns. 1 the oil filter is now trapped behind the supercharger and turnbuckles, which makes it a lot harder to remove. My 2nd concern is the silicone piping used on the charge side of the supercharger. I would highly suggest using aluminum rigid pipe to reduce expansion and boost surging. Silicone couplings would still be fine to connect the aluminum piping.

[@someonesomewheresomdeday]

I've always wanted to see a roots blower with a variator drive on a diesel. The thought of the blower being on the same constant speed could be very interesting. Just peak torque all the time and a boost curve like a table top. I always enjoy your experiments, keep it up!

[@jhrubicon1470]

I love this channel so much!! He makes you think outside the box, which is great!

[@douglasmayherjr.5733]

I would think under 12 psi of boost would be safe, based on what the old 6.2 and 6.9 diesel turbo kits were designed for. Anything in the 17+ range would probably make your head bolts unhappy. A boost dump valve controlled by the madman gauge would probably be the safest and allow small steps to see exactly works best. Thanks for the videos, Jimbo

[@Corinator]

I'm a Benz guy so an electronic bypass valve is not something unfamiliar to us. Many supercharged Mercedes engines like the m113k in my daily driver use a small DBW throttle body as a bypass valve to gain more finite control over boost to improve smoothness and fuel economy. Rig up some sort of TPS sensor or WOT switch to control a bypass valve electronically to resolve that issue. Seems like an easy fix using an Arduino.

[@jeremypike9153]

If you aren't getting the boost you want try playing with pulley sizes on the engine and supercharger. All diesels are overbuilt so as long as you provide enough fuel the engine should have no problems handling boost pressure or high cylinder pressures. Running a serpentine belt setup will definitely mitigate belt slip if it becomes an issue. You don't have to run sealing washers on the super charger either use ptfe tape or thread sealant works just fine.

[@bcubed72]

I love how when you look at the supercharger pulley-forward, it looks like it's sporting a black monocle and a comically small top hat!

[@herbertgearing1702]

I don't know why exactly maybe I'm stupid or just a contrary person but I enjoy the way superchargers sound, and the way they bring power much more than turbochargers. I know they are less efficient and they don't usually make as much power, but I like the way they drive and would love to see more affordable cars use them. I think the gas mileage government mandates and the way they are applied creates a situation where fun is missing from mainstream inexpensive cars and the less expensive the harder the needle is pointed to fuel economy as the primary consideration in the (fuel economy/emissions /reliability /performance) comprise. The rotary engine, the 2 stroke, the air cooled, the supercharger, and the square pickup truck are all basically absent from 90+% of the market because of government meddling. They still make cars which are fun to drive but they have become the exclusive domain of the rich by using the average numbers across models based on sales volume the auto makers couldn't build a fun to drive inexpensive model in any serious numbers because they would be in violation of the fuel mileage and emissions regulations. Not because there's no market for that car but the government has decided that poor people are not allowed to have fun.

[@davidfink4963]

Your content is so awesome. The experiments thoroughly entertain and bewilder me. And your aloofness adds so much comic relief. Can't wait till next Sunday.

[@htimmermans1938]

Very tight packaging, great work!

[@generaldisarray]

9:32 just a thought but why not run the original/regular belt around the crank, water pump and alternator, and then have a double pully on the alternator, with a separate belt, to drive the blower. That way you'd get far more engagement on the crank and alternator, and you'd also get better engagement on the alternator and blower.

[@sadaaromin13]

Waist gate comes to mind. Typically used to relieve excessive exhaust pressure. I think if used on the intake system they will flow enough to keep your pressure at target. They are simple and mechanical.

[@genetomblin2883]

So true some form of positive scavenger air is absolutely required on a 2 stroke diesel

[@AmericanLocomotive1]

The easiest thing to do would be to simply put a throttle body on the intake of the blower attached to a waste-gate actuator (or electronic actuator with PID control). Once target boost is hit, it will start throttle the intake air and regulate it. The only problem doing it that way, is that it might cause an increase in discharge air temperatures as the blower will be working against a greater pressure differential. You could also put a throttle body on the discharge side and route the air back into the inlet of the blower.

[@felixaudet5860]

Wonder how this engine stacks up against a 800cc TD engine from a Smart Car.. Great stuff.

[@kd5inm]

I guessed 10psi on the boost so I wasn't far off and I had faith your design is good! I would run it as it is and gather data. Like everyone else says, egt's are the thing to watch and I believe you've got a good indicator for that.