HOOKER CAST TURBO MANIFOLDS VS E-BAY TURBO HEADERS-BOOST PSI VS BACK PRESSURE. BACK PRESSURE VS HP!

[@takuacheperformance4740]

This COMPLETELY makes me NOT regret selling my manifold turbo setup. On to better things now!! Thanks for the results!

[@davidw.thatmsdguy8952]

Another successful testing session showing the facts! Good stuff and thank you for all your hard work over the years. It definitely gives guys a opportunity to make a informed decision without having to only listen to the guys selling the products, which would be the better choice for each individual based on what their needs or wants are!

[@goodmanboattransport3441]

I'd like to see the back pressure with one of the wastegates blocked off on the tubular system tested as well. The change in back pressure and HP in the Hooker system I think is due to the increased back pressure and the wastegate unable to blow off enough exhaust to bring it down. I also expected the cast iron manifolds to retain more heat energy and drive the turbo harder, and I thought we'd see a better boost number lower in the RPM range, and that didn't seem to happen. I'm going to have to watch this one again taking note of back pressure reading line location. Awesome info as always, thanks Richard for your dedication to excellence in automotive performance testing 👍

[@madmiata1887]

No YT channels talk about back pressure except for Banks. Awesome data.

[@heythere6922]

Higher back pressure results in less exhaust gases leaving the cylinder, which, in turn, results in less intake air and fuel entering the cylinder, and less power output. On a turbo setup, you need exhaust pressure at the turbo to spin it fast enough to create the boost you're looking for, but any other exhaust pressure increase results in loss of power.

[@100pyatt]

CORRECT ✅

[@Fackler91]

Hello like minded people

[@tayvonrose2528]

Wassup dude

[@I_like_turtles_67]

When did hooker come out with these?

[@Fackler91]

@@I_like_turtles_67 they have been out. Id like to see the summit racing manifold tested with it dual gates and stainless steel cast

[@I_like_turtles_67]

@@Fackler91 I realized after clicking they've been around for a few years. Pretty good option for someone going LS turbo route.

[@thetruthspeaker1978]

Lol .

[@Liberty.Francis]

The big aspect to consider is how long that eBay manifold will last before it cracks versus the more robust cast manifolds.

[@PANTYEATR1]

Great test Mr. Holdener. The back pressure surely could be preventing the turbine from spinning as fast as it could. It could also be diluting the cylinder mixture and acting as a buffer.

[@kaidenking7535]

Myself and many others running the hooker setup would really like to see these things pushed further to see data and their limits. I’m making around 960whp with them and I’ve seem to basically hit a wall for power when everything else is good for 1300+. Thanks for the videos.

[@Levibetz]

If you've got an extra input it's not too hard to add a sensor for it. I'd be really curious to see that measured at various parts of the manifold, like at the turbo, before the crossover, etc.

[@Levibetz]

If you've got an extra input it's not too hard to add a sensor for it. I'd be really curious to see that measured at various parts of the manifold, like at the turbo, before the crossover, etc.

[@davidpartridge4980]

Steve Morris has a vid making 1200hp using them so they will make more just need the right setup or base hp to start

[@goodmanboattransport3441]

Would adding an additional wastegate help, like the tubular system, or alternatively, adding a second turbo and wastegate with it, I'd think you might be pushing the bottom end to it's limits at 1500 HP 😀

[@3800TURBO]

I think they got a cork in there some where. Maybe a spot in the casting design that's restricting flow.

[@Sleeperdude]

Great information thanks for sharing. I ran a big block turbo car for years with a manifold on one side and a header on the other

[@Turboppv]

Mave my 6.0 ls set up the same way

[@alexunderwood7899]

I think the real interesting thing to look at would be HP/PSI on each engine across the dyno graph since the boost levels weren't even. That would probably somewhat normalize the results, although not completely. Just jam it into a spread sheet and calculate it out, if the dyno software doesn't.

[@3800TURBO]

They were both even at 11psi up top so no need to over think it. The free flowing bigger pipes won.

[@jridenour31]

@@3800TURBO Yes, less backpressure obviously wins up top. That's not the only thing that matters. The boost curve on the manifold setup is screwed up. There's no way it should take 6000rpm to reach peak boost and be down 2-4psi until then.

[@tim4g63fast]

Bernoulli's principal. A decrease in pressure = increase in flow. I would guess the decrease in back pressure allowed more efficient spool which allowed the compressor to do I its thing more efficiently. Basically the entire turbo is working more efficiently as the back pressure drops.

[@kyletice811]

drive pressure being lower or closer to 1:1 with boost pressure is just more efficient on the top end. I'd be interested to see cams with high overlap vs none on high backpressure setups.

[@exploranator]

SUGGESTION: measure the BSFC of an engine during runs at various throttle settings. Use a Hellion sytem on a Hemi, which uses full-length headers before each turbo. Find which uses the least BSFC, has the lowest EGT and backpressure, etc. Then use cast log manifolds with the exact same turbos.

[@LS_Rooster]

Finally some more dyno videos! Keep em coming!!

[@willagresham2978]

I would guess the increased back pressure makes the scavenging effect less efficient and leaving more inert gas in the combustion chamber for the next power cycle.

[@needmoreboost6369]

Yeah Richard! you read my mind 👍this will be interesting! Of course my vote and preference is good fabricated long tube but bolt on cast stuff can be great for an easy street set up

[@383mazda]

Makes sense - back pressure is bad because during valve overlap you'll have dirty air flowing back into the cylinder and intake. Less clean air = less power. Would be interesting to see this test with factory cam with 0 overlap.

[@177SCmaro]

Virtually all cams have some overlap, including factory cams. Engines don't function very well with 0 overlap.

[@Thomamps]

The pressure in the exhaust between the exhaust valve and the turbo is created by the piston pushing the waste gases out on the up stroke. This requires energy from the closed system, more pressure requires more energy meaning less is available for the output. It's a simple conservation of energy equation.

[@stormracer05]

Nicely done, I think it comes down to packaging and fabrication skill. I would also like to see a test done using stock manifolds as a budget builder would.

[@richardholdener1727]

THEY WORK GREAT

[@loganolsen8415]

​@Richard Holdener I have a question. I have a silverado with a cammed lq4 that I want to turbo. Eventually I want to go 408 with a big cam. I'm only planning to run 15psi on both setups. The question, is there any benefit to running a vsr80mm or bigger vs 7875 at that boost level?

[@brudevold62]

A twin scroll comparison would be interesting divided vs non divided, single and twin scroll and if it's out there twin turbo twin scroll.

[@mattmorrison6958]

It would need to be done on something other than a v8 where the two inlets can isolate all of the negative cylinder to cylinder interference during each's valve overlap. Having two divided turbos would work on a v8, but only if the runners crossed banks to properly pair them, which is why it's only really done on "hot v" setups with the exhaust in the valley where the intake manifold typically sits. 2 rotor, 4cyl and 6cyl can utilize a (single turbo) divided turbo setup but you won't find any tangible benefit with 8 cylinders since they can't all be meaningfully separated

[@miquelanesto1762]

Normally they would say send it to Richard but now, Mr Banks, has done this and calculated the hp that is lost by back pressure ratio.

[@nigel2447]

For sure the back pressure made a difference. You reduced the pumping loss on the exhaust stroke for the same air flow on the intake. The question is why was the back pressure less. If you measured exhaust temperature and exhaust pressure at the inlet of the turbine that may help figure out why. A guess would be the headers are radiating more heat than the manifolds and lowering the specific volume of the exhaust gas which will equal less pressure for the same mass flow. Probably more to it, could turn into a science experiment real quick.

[@3800TURBO]

I'm wondering if the cast manifolds have a cork somewhere. May be one spot where it's just not large enough. Seen this difference even between different factory manifolds on turbo setups.

[@nigel2447]

@@3800TURBO Thinking out loud - Definitely the contributing factor would be the flow capability of the manifolds vs the headers, but the turbo/wastegate are the governing flow devices, so trying to figure out how the pieces fit together. I did not see where the exhaust pressure was measured, but if it is just before the turbo, then up stream flow restrictions would not directly cause the pressure to be higher in front of the turbo. Since between 6000 and 6500 rpm boost conditions are the same, that would mean that compressor power required is the same and turbo shaft speed is the same. That would also imply that the turbine volumetric flow is the same since turbine speed is the same for both cases. To get the intake conditions to equal in the two cases, the higher pressure and likely higher temperature case would require less turbine mass flow to drive the compressor than the lower pressure/temperature conditions. For the turbine side it is an energy balance, in both cases turbo shaft power would be equal, but the higher pressure and likely hotter air will allow more energy extraction and require less mass flow to get the same shaft power. Long winded way of saying I agree that it is the flow restriction of the manifolds, just trying to figure out the impact to the devices that will most directly impact the back pressure at these levels of pressure and flow.

[@177SCmaro]

It's probably more to do with the volume of the manifold compared to the headers. Obviously here is more volume in when each cylinder has a pipe then a manifold that merges everything together quickly. Same amount of exhaust being created in a large volume equals lower pressure.

[@laurencec2353]

If you’ve watch any of these videos before it was pretty obvious which would win. Richard should run both hot sides N/A without a turbo on them. I think it’s obvious the headers would flow more and make more power than hooker set up N/A but it would be kinda interesting seeing what the difference would be. Anyway as always with all his dyno runs the more power N/A the more power under boost.

[@lukeschannel650]

Richard had the best tech channel on KZbin

[@MrScottt28]

Sooooo. We have always said "just get all the exhaust to the turbo". S log manifold does that. I've Lay's said that if headers make sense N/a, they make sense boosted. So maybe improved scanning is resulting in less backpressure. Help me here

[@JC-gw3yo]

Great test... Even thought the Hooker manifolds look good, the tubular headers create lower back pressure.. Tubular manifolds for me...

[@ticojason8868]

Richard is the GOAT. Period. Testing and results. Nobody can compare.

[@paulberkenpas9382]

What A/R exhaust housing was that Precision turbo? .81 or .96 ?

[@CJ-uu3lk]

Would also love to see the stock manifolds vs tubular vs Holley manifolds for a bottom line NA and with boost

[@andyharman3022]

I think back pressure accounts for about half of the 6% difference in power between the cast and tubular manifolds. The other half would come from increased airflow and the extra fuel that comes with it.

[@CFM-8344]

Richard have you seen the newer Summit LS manifold? It's a true divided manifold with two wastegate locations. May be a good compromise.

[@mattyancey28]

Interesting!

[@mcfero1]

Not in price

[@GrimReaper528777]

Thanks for redoing this video. So headers do work with boost just like cams. I would like to know if the NA engine sees a similar power difference with the headers vs the Holly cast manifolds.

[@richardholdener1727]

THIS IS NOT AN NA EXHAUST

[@justin_parks]

@@richardholdener1727 you could still run them both na tho, please lol

[@ragtopdeluxezl1]

@@justin_parks yeah, He does that a lot. annoying...

[@TheBDD1970]

It takes power to compress the gasses, so it makes sense to me that you lost power. The backpressure was evidence of wasted energy expenditure. I am curious if a hot side turbine change could help reduce that at all? In other words how much tuning can we find in the hot side without killing response to compensate for less than ideal mechanical limits like exhaust routing.

[@Josh-py2in]

I think what everyone is neglecting is the dual wastegates. The majority of the power gain is after the vehicle hits 11 psi of boost and the wastegates open. This is because there is significantly more flow, which is reducing back pressure and increasing hp. Sure the headers flow more, and I'm sure there would be some power increase, but it wouldn't be this large with the same number of wastegates. The only way to accurately perform this test would be with the same number of wastegates on each setup.

[@richardholdener1727]

how exactly do dual waste gates add flow?

[@BigRedRocketScience]

My theory: More back pressure means you're having to drive the turbo harder to make the same boost, which means the engine's ingesting the air with more difficulty because of residual pressure from the exhaust stroke where it couldn't escape as easily due to the flow restriction (or lack of scavenging without header primary tubes) a.k.a. back pressure... I talked in a circle.

[@ihcr100]

And higher peak cylinder pressures(theoretically) although as someone else said, there may be a little more residual exhaust diluting cylinder air composition.

[@MegaRomans01]

Very enlightening as always, thanks Richard

[@wlrottge]

I could go pull out my chemical engineering fluid dynamics book, but....not sure what I could really calculate without more data. Regardless, yes, I could see the pressure difference making up part or most of the power difference. Think about a pressure washer, put a big nozzle on it and it moves the same quantity of water as a small nozzle would, but the engine has to work harder to do it. It isn't a perfect analogy because water isn't compressible like a gas is, but you get the idea. Back pressure indicates restriction to flow, which means more energy required to move the same quantity of fluid.

[@95GTSpeedDemon]

I wonder if exhaust overlap has an effect. Would the air charge be more diluted at a given back pressure figure if theres more cam overlap? Im going to have to watch the turbo comparison video again. Not as apples to apples as it adds the compressor variable.

[@oldschool6268]

Didn't this video come out a few months back, turbo headers were the best right ! Glad I have mine.

[@harperjmichael]

NA test is needed with the cast iron manifolds and the turbo headers with Y pipe. I think you'll see a significant difference there and thus one of the reasons for the boosted difference.

[@HerrPoopschitz]

How exactly do you run a turbo header na?

[@jmullis78ify]

@@HerrPoopschitz take the turbo off and just run a regular exhaust pipe off the manifold or headers

[@jmullis78ify]

@@HerrPoopschitz I seen guys run those turbo headers without turbos and just run the exhaust out the fender

[@HerrPoopschitz]

@@jmullis78ify Ah. Goofy lazy people. Gotcha.

[@elementaljosh]

@@jmullis78ify You don’t even have to take the turbo off, just disconnect the intake and have the engine breathe atmospheric pressure air. That way the NA combo still has a bit of the back pressure, just not as much as it would under load

[@leam1966]

it would be interesting to see what it would be if you stuck a extra gate on the cross over of the hooker set up . but no back pressure results in bad turbo lag so the right size header and cross over is important.

[@theozman38]

Ok. Correct me off I’m not dissecting this test properly. The reason the tubular headers produce more hp is because of the exhaust tubes are not in conflict with the exhaust flow except at the end of the manifold but they are directed freely through a pipe. The hooker headers are in flow conflict right at the beginning and creating flow problems. Stock manifolds would be better than the hooker headers?? Something to wonder. !! Thanks Richard!!

[@totensiebush]

I'd be interested in seeing a comparison of those two exhaust setups NA and see how that compares. I'd love to see longtubes (whether fancy turbo headers for a race car or typical LTs) thrown in too, all 3 both NA and turbo.

[@michaelspiering7585]

I think it's a reasonable assumption to conclude that the change in horsepower difference is attributable to back pressure change. To me, it raises the question of does the back pressure make it harder for the piston push against the pressure, or does the pressure make it harder for the turbocharger to push the boost into the combustion chamber, or both?

[@2GSpyderTurbo]

Do you think the dual wastegate helped keep the backpressure down due to better bypass volume? I would like to see the hooker set up with a larger single wastegate and both header combos with better boost control. I think the difference will narrow a bit. What do you think?

[@ZONES89RS]

We know back pressure was less at the same 6000+, so I don’t see it being a issue having another waste gate. But someone might have a reason that I cannot come up with. Consistent boost numbers should make it irrelevant

[@2GSpyderTurbo]

@@ZONES89RS running the conservative boost numbers that they are, wouldn't the gates be bypassing the most out at 6000+? There is no doubt the tubular headers are better, I just feel like there are other factors that led to the massive difference in backpressure.

[@ZONES89RS]

@@2GSpyderTurbo I am confident it’s the sloppy manifolds VS the tubular headers that have a very strict direction and flow. Manifolds are cramming together exhaust gasses where the headers are directional and essentially helps fluid dynamics(gas). The dual gates are superior for control especially at higher boost levels. It’s hard for me to wrap around them causing the difference in power. I can see consistency for sure. But 12 psi? That isn’t hardly anything .

[@CrazyDrewDevelopment]

I can only think this is directly related to pumping losses and the ability to effectively evacuate the combustion chamber. I wonder if less exhaust lobe timing would be better on the hooker setup

[@CrankAddict]

I feel like back pressure is a large part of it, but with those pressure ratios of the tubular manifolds the turbo is going to be spinning much faster. I think that the tubular manifolds put the turbo more into its sweet spot and that made half the power gain. It could easily have shown LITTLE GAIN or even NO GAIN if a smaller turbo was used that has a different "sweet spot".

[@Orange_pickles]

Help me understand, I thought that, like for like, compressor wheel RPM had a direct relationship with boost pressure. It seems like this is a cylinder filling/ pressure reversion issue.

[@CrankAddict]

@@Orange_pickles compressor wheel speed is same as turbine wheel speed. The veloctiy (air flow) of the exhaust as it goes from manifolds to downpipe is what determines wheel speed. Backpressure is like boost, it is a measure of pressure and not necessarily airflow. You can have lots of boost and little air flow, and also you can have lots of backpressure and little air flow.

[@DoctorMotorcycle]

I see what you're saying about the turbo being in the sweet spot, but 11psi is 11psi, and the motor picked up 45hp. 40-50HP is actually a really common gain from what I've noticed, Full Race did a test back in the day comparing a log-style manifold to an equal length 4-1 manifold and their honda picked up 40HP. Gentle curves with merge collectors w/exhaust pulses is always going to be better than having the gases make sharp 90* turns. kzbin.info/www/bejne/ipyyd3Voh5emp8U

[@blue_dream_steam]

Now we need a trick flow turbo header test, on a 5.3 preferably

[@otm646]

I would love to see how the cast turbo manifolds like the Summit offering stack up here.

[@Dr_Xyzt]

I'm thinking about that time you did manifolds vs headers with a supercharger and saw more boost. That was a weird one. -- Here's my only hypothesis: Because the exhaust gas is under pressure which makes it more dense, the tune frequency for the header is still valid. You still have that good factory intake. The cylinder gases are still getting discharged to a primary tube that likely holds more volume than the cylinder, so the system is still able to resonate and function properly.

[@claytonhaske]

I have a stainless steel version of the hooker cast iron turbo header. Got it on ebay, and can't find anymore like it.

[@jonathanmoreno526]

Shoulda talked more about boost response between the two. From what I gathered, the tubular made more boost quicker, essentially spooling quicker. Can someone speak on this?

[@hemi-denny]

Interested too …….

[@BLKMGK4]

Richard, you're using a Holley EFI for the tests right? Why not grab a couple of MAC valves to get turbo control? Once you got the PID figured out you could probably use one of these to really get some some consistent boost levels when testing so long as the wastegates had enough authority. Couold even use shop air to better control it by adding pressure on the gate. Keeping the boost level even would really help on tests like this I think. Wish there was an easy way to measure the CFM into the intke too.

[@95GTSpeedDemon]

Shit, "common" knowledge in some circles was that the turbo was the biggest restriction and the pre turbo exhaust didnt matter much... Seems there might be some error to that. Very awesome test. I built my turbo setup with that info in mind... Im thinking i may have made that in error now.

[@DoctorMotorcycle]

Full-Race did a test on one of their 300HP Honda's, and going from Log to Tubular Manifold they picked up 40HP on a little 4 banger. It convinced me to change the header design on my turbo kit.

[@177SCmaro]

The turbine is a restriction but I think what is overlooked is restrictions can add up. It will take more hp to pump exhaust through 5 restrictions then is will just one.

[@oliverscorsim]

I say this was a pretty perfect example of pumping losses.

[@rorycollett3744]

When you run log style you have less manifold volume Wich works like a smaller turbine housing. That’s y tubular headers make these changes back to back. You can stay log and run a much larger turbine housing and will spool faster make more power and torque below the curve and also the same or more total hp

[@WVXL64]

I think the higher backpressure creates lower HP levels through charge dilution. The less backpressure, the more spent gasses you can get out of the cylinder, letting more of a fresh charge in. I also think the Hooker system is a great system for a street bound Turbo LS set up. It's much easier to package in a street car. Now if you're running at the track, and looking for all the horse powers, then you would want the tubular, but in a race car you're less worried about how it looks, cutting the car up to fit it, etc. One thing I wonder though, if you plumbed both into a full street exhaust system, how much would that of leveled the playing field for this test?

[@moparman1506]

Yes again it’s an air pump more back pressure will effect flow be a good balance of both for high hp I think

[@hemi-denny]

Very interesting vid for sure, keep them coming Richard. Would really like to read the real reason , since I’m also working on a turbo (gen 3 stroker hemi) build ….😉 Kinda new to all this stuff but I think it has something to do with exhaust pulses and wave tuning…. Probably would see the same affect NA then … .

[@ThomasTT496Vega]

I get the increased back pressure killed power. The back pressure was measured from the turbine inlet, why was the back pressure higher? One would think if the manifolds were the restriction the back pressure would be less at the turbine inlet.

[@DrTonyTheBaptist]

Adding a second wastegate on the crossover of the Hooker setup might drop the back pressure quite a bit.

[@Stale_Mahoney]

well a engine is nothing but an air pump in the end of the day, if you need to push harder to get that exhaust out you use momentum and get a backpreasure that prevents the engine from running as free, so i think it is fair to say that it can be contributed to the backpreasure as it directly work against the engine, a turbo like a supercharger does steal hp, although it is more effective than a supercharger. i think a interesting thing to have tried would be to get a air compressor and run the engine at the same 11psi without a turbo or charger, but an external air source to see what 11psi and no restrictions of spinning up the turbo would be.

[@MarshMellowF450]

Would love to see this with equal length headers

[@mitchellsnider4198]

Only thing OTHER than back pressure (and lower VE because less of the gas is able to leave) I can think of is if there was some more heat transfer from turbine to compressor on the cast setup? That seems like a stretch though. Maybe faster turbine speed due to faster boost response also led to a higher efficiency/cooler charge and better VE too? That’s still a knock on back pressure effect though.

[@bcbloc02]

I have gone to a bigger sized AR and gained similar power with everything else being the same so I would say sure the power comes from the reduction in back pressure.

[@daleanderson7629]

30hp hot air pump/compressor can't help the VE of a motor. the extra 3ft of exhaust path and bends would surely change the resonance and flow of each bank and therefore distribution. humble testing ideas -either a big and small gate on the same system in the same place (or 2 in the same place, 1 locked out, then both) does it make an efficiency difference in the zone before boost creep becomes an issue. -does having the gates closer to the ports let the merge pipe cool slowing spool.

[@dmc5681]

More back pressure reduces air flow through engine due to less favourable pressure ratios and also causes higher pumping losses as piston works harder to push the exhaust out

[@fustyblatherskite2142]

It is obvious that the tube headers are a more efficient design. You mentioned that the tube headers had two wastegates and the manifolds had one. If the manifolds had a second wastegate installed in the cross-over pipe, would this reduce back pressure some and bring the HP closer to that of the headers? There are two advantages that I think the manifolds should have, one is reliability, two the exhaust should retain more heat for better turbocharger function. But I realize that these two advantages may not overcome the flow advantages of the headers.

[@lifeonadime4703]

Great vid showing how back pressure is not a good thing 👍. I knew it cost power and can hurt boost curves but I didn't know even that little bit of Bp could rob that much power. More air in=more air out=more air efficiently in = more air efficiently out = mo powa!

[@BlàckÐèàth]

In my mind its the same concept if it were a N/A combo. And you've proven it in other tests where you ran extremely long exhaust tubing. Exhaust restriction robs power whether its attributed to manifold, muffler, or undersized tube dia. they're all causing additional back pressure.

[@Thumper68]

Higher back pressure big changes in scavenging is why the headers do a better job making hp. The runners for each cylinder is even length or close to it so scavenging is same.

[@sethjoyner391]

Purrrrrfect video...praying this test would go down..thank uuu

[@michaelblacktree]

Hey Richard, have you ever tested a turbo manifold vs a regular manifold (or headers), on a naturally aspirated engine? I think it would be interesting to see how much power the turbo manifold gives up, just so you can install a turbo.

[@leensteed7861]

Seems to me they both controlled boost fine but the headers got up to pressure much faster and with much less restriction. More of the kinetic energy got to the turbo to spin it harder instead of turning into heat and pressure

[@chrispatterson8073]

Thanks Richard, great product review / comparison. One question I have is price vs longevity.

[@andrewweltlich9065]

Exactly. It was no surprise that tubular headers make more power, but they are nowhere near as durable as cast manifolds in a turbo setup.

[@PaulThomas-qo9vy]

Thanks Richard! I am curious whether the higher B/P was a function of the Hooker casting restrictions or waste gate (WG) size? Could a "Y" pipe & flange replace the single WG, then 2 WG's be installed on the branches of the "Y" to see if B/P would significantly drop with the increase in "window" of 2 WG's. Any thoughts Mr. R. H.? How smooth are the internal castings of the Hooker manifolds? Has anyone tried porting or Extrude Honing? Thanks, Paul from S. Central Tx.

[@radioactivefabrication]

Yes backpressure will affect power. Higher backpressure the lower the power due to it not moving the exhaust as it should, if it gets high enough you can lose power from it polluting the next combustion cycle because it can't scavage enough exhaust fast enough.

[@supercharged6771]

Well done, and would not have guessed this

[@brett8090]

If power is relative to flow and restriction is contrary to flow. It stands to reason that any restrictions to flow will restrict power. The tubular system just plain flows better.

[@LS1FREEK]

Backpressure definitely makes a difference, but not all that HP is gained just from that. I think probably 50% of the HP gains is from scavenging increase front the longer tubes and smoother air flow.

[@rileydalton3958]

Hey Richard you should try the stock cast manifolds with 2 wastegates and compare to the tubular header manifold

[@bartpang]

Did the log manifold need less fuel per boost pressure than the tubular? Is there a direct correlation between fueling and back pressure? Also with less back pressure, can you run more or less timing?

[@thunderrollin]

The back pressure is measured at the turbo flange so the manifolds will not change the back pressure readings. The dual waste gates are the factor. Way back in the eighties we put an extra waste gate in the system to relieve excess back pressure. The exhaust manifold/headers will contribute some HP but the lower back pressure will contribute equally.

[@briand2614]

Fun video. I’m a bit confused about the back-pressure. Was it measured nearer to the head or nearer to the turbo? Ideally we would measure it at both places to evaluate the exhaust manifolds. Higher back-pressure should result in higher cylinder pressure when the intake valve opens. This is going to resist flow and reduce the total mass of air going in, or lower volumetric efficiency. The dyno doesn’t lie, there is less torque, so less air and fuel, assuming something else is not stealing power.

[@BigRedRocketScience]

It looked like he had a tube right under the turbine inlet, so it was the pressure driving the turbo in these tests, not the pressure at the ports.

[@button-puncher]

Why weren't you using your electronic boost controller? I still loved the test. Restriction/inefficiency is seen by the back pressure developed. I really like the design of the Hooker setup. Hopefully they will create a larger higher flowing version.

[@BLKMGK4]

Yeah, he has an aftermarket EFDI and I thought he got an electronic controller that stood alone as well. Badly needed for this test :(

[@bradwinsor9677]

I'm curious on if it's the type of merge they use. I'm running an action turbo manifold that's a stainless 3in pipe basically. Pass side dumps into the same pipe the driver side feeds into. It's on a 5.3 now but I'll be moving to a 403 soon and hoping this setup doesn't restrict my power output.

[@tylerphelps4868]

Even though there was no change in AFR, is it possible that there was a greater air mass with less backpressure? Boost is a measure of restriction, not airflow. Could it be that the engine became more efficient and the given mass air was achieved with a lower boost number which would mean a greater mass air when boost was matched? I realize AFR didn’t change but is there enough leeway in the Holley controller that 1lb or a 1/2lb of boost was compensated for in the fueling?

[@shawnbergquist9846]

Would the back pressure on the manifolds come down if you were to make a bypass pipe parallel to the passenger side manifold. So the merge on the passenger manifold would not be a factor anymore

[@Levibetz]

I think the answer is pretty clear, back pressure absolutely kills power (given the same boost). If it does it NA, it does it under boost! Another thing to consider, if this engine was on pump gas, more back pressure will make the engine more sensitive to knock, leading to the tuneup requiring less timing and of course killing power potential. I'd be curious to see pressures at the port/runner vs pressure at the turbine as well as pressure in one bank vs the other. Now the real question is, if you put long tubes on an engine with collector extensions, and put the turbos there? Does it gain power? My logic says yes, although it would be ridiculously impractical to package.

[@BLKMGK4]

Hellion systems do this and some people with pickups put the turbos in the bed - it works!

[@Levibetz]

@@BLKMGK4 Well yeah, there's lots of rear mount setups. I'd be more interested to see a test that's more back to back like you could do on a dyno, really isolate variables.

[@kevinengland4042]

Is it fair to compare this change to putting headers on an N/A engine? Gaining 20hp N/A would be roughly 40hp with 14.7 psi of boost....

[@seanadams8444]

Great video and comparison. I'm curious what the heat differential was between the two exhausts closest to the turbine wheel. Possibly the cast iron sapping more heat versus the header transporting more heat to the turbine? Temp probe would be great to debunk that being that heat and pressure are relative.

[@richardholdener1727]

THE REVERSE WOULD BE TRUE FOR HEAT

[@moparmuscle8749]

I'd also be curious to see the EGT differential between each setup, given that PV=nRT with more back pressure EGT should also rise I would think as long as timing, a/f, etc. stays consistent. Great video Richard!

[@DodgyBrothersEngineering]

The evidence suggests that back pressure decreases power, but is there something else hiding in there? Did the back pressure somehow influence the exhaust flow post turbo?

[@needmoreboost6369]

That’s a lot higher back pressure than I expected! maybe they aren’t as pretty on the inside lol but my guess the gate is probably the biggest problem and log manifold design’s in general can see some nasty high pressure points. how smooth is the flow to the single gate? I can’t imagine it’s dead consistent

[@nickstone302]

Ever tested the speedway motors LS turbo kit on a 5.3. Same manifolds with VS 7875

[@richardholdener1727]

no sir-but I'm sure it works

[@DruNicholsMD]

Awesome Tech! Thanks Richard!

[@chriskane993]

Hey I was thinking it would be interesting to see a comparison between a self tuning/learning system with just basic input like you can do in your garage vs a Dyno tune

[@mattmusselman6499]

I think the lost hp could have been caused by the pumping loss of the piston pushing the exhaust out of the engine due to higher back pressure. But that is a pretty obvious reason so maybe I'm wrong.

[@Eqium]

always thought the log type manifolds will cost some power, mine are custom made headers very interesting

[@PursuitofSpeed]

One interesting comparison may be spool time, if the Hooker manifolds get a turbo moving from idle quicker (IE: gaslight stomp).

[@hydrocarbon82]

It will largely depend on the total exhaust system's volume, and a bit on how much heat is lost. You can size the x-over on the Hooker much smaller than you typically see (2-2.25") and quite possibly have better transient response. The headers also have much more surface area to lose heat, which Richard has shown will slow turbo response.

[@Shawn_lsx]

@@hydrocarbon82 The cast will get hotter and hold way more heat then stainless tubular. Think of a cast iron skillet.