JUNKYARD TURBO LS BACK PRESSURE TESTS (HOW TO: MAKE MORE HP)

[@adampatterson707]

Back in the early 80's one of my running buddies got a turbo trans am with that silly little 301 V8. We had the local exhaust shop straight pipe the mufflers and then we installed a (test pipe) and tossed the converter. I'd almost believe that it cut that T/A's 0-60 time in half. It could smoke the tires from a standing start after that, and it sounded really cool.

[@excalibur3895]

Somewhere down the road I want to get my hands on a stock one of those cars. Then just make basic changes to create a more efficient system. I don't think it would take much to make that little 301 a fun little powerplant. The fact that all the Pontiac guys (I'm one myself) dislike them, just makes me want one more!

[@BLKMGK4]

"Boost" is a measure of backpressure in the intake. This becomes most obvious with a belt driven supercharger where you swap on better heads or intake, lower measured boost, but make more power. Turbos just often mask this because wastegates maintain pressure to a set point as improvements are made. Meanwhile the shaft is spinning harder...

[@otm646]

This is why I boost itself is a terrible number and concept. You need to be talking about mass air flow. The engine is just a pump, you need to measure how much air it is pumping.

[@rwdisgreaterthanfwd]

Wish more people understood this.

[@midnight347]

@@rwdisgreaterthanfwd no shit man. People talk about boost like its the same across the board across every type of car or truck and forced induction. "How much boost can it take?" Is an annoying question that bugs me lol. 10 psi on a big ass turbo on a fully modded engine is totally different than 10 psi going to a stock motor via a smaller turbo. Not even comparable. The airflow on one is going to demolish airflow on the other despite both running 10 psi lol.

[@BLKMGK4]

@@rwdisgreaterthanfwd To be fair I was one of them! I had a belt driven supercharger on my Mustang MANY years ago and when heads were ported etc. I was upset I'd lost boost. Except - the car was clearly faster! It took awhile but I get it now but back then hardly anyone understood much of this it seemed and people ripped EFI off for carburators. Meanwhile I was swapping on turbos lol.

[@BLKMGK4]

@@midnight347 Yeah,. it's always weird when you swap turbos, run the "same boost" but end up with MORE power! Nowadays we can datalog backpressure and many other things to better understand but that wasn't always the case for sure. People still don't get it though and Richard's videos really help dispel many of the myths :)

[@justinjones5288]

Its called MANIFOLD AIR DENSITY! Gale banks has been providing information like crazy

[@davidciesielski8251]

Hi, he is talking about colder/smaller more oxygen dense air, Richard is saying same charge air cooler... here is what happen when you change heads or exhaust.... I love Gale!!!

[@hom240]

As much Richard loves turbos you have to wonder. Do ALL his vehicles have turbos? What about his lawn mower? Great video Richard.

[@elkameleong]

If they don’t have turbos, they all have cams

[@Faolan161]

I get it... I have done porting for my daily drivers, cams, just not turbos yet... But when I ported my pressure washer, it's far more reliable, and runs better. The motor would pull down in rpm because it was slightly small, and now it doesn't. I ported my power trowel for my work, and it starts better, while being more capable. I ported a gas powered sweeper, making it far more effective - 8k rpm to 13k rpm... I ported my concrete saw, and it starts easier and faster, and cuts faster... Do it right, and your equipment is more reliable. It's not always silliness... even though it may sound like it 😉😉😉

[@GapSauceYoutube]

I had a test on my channel recently where an s366 slightly outpowered an s480 Back to back, same boost. Turning the bigger compressor when it's not required did infact create more backpressure and it showed on the dyno as well as the boost control. Thanks for providing us with these tests Richard, cheers. 🙂

[@richardholdener1727]

an s480 had more back pressure than an s366?

[@GapSauceYoutube]

@@richardholdener1727 More duty cycle was required to keep the wastegate under control with the s480 at 10psi. It's probably important to mention that we were only testing at a knock limited 10psi on pump fuel in-car. Had we increased the boost with e85/Race fuel, obviously the s480 would have less backpressure as the testing progressed to higher boost levels. But as far as relevance goes in regards to how most people would use the car on the street (i.e., pump fuel, heat soak, knock limited etc.) I thought it was notable for the majority of street driven cars. I should also mention that we did not have a backpressure sensor, just backpressure against the wastegate to come to that conclusion, and I am definitely open to the subject :) Also, the s366 made a few numbers more on the same boost/timing which also leads to the lower backpressure hypothesis in my opinion. *There were no other changes to the car other than the Turbo swap.

[@stevenbalusik8997]

Great video and tech Richard. Understanding all the relationships at play is so crucial to optimizing and you did a great job explaining.

[@harmankardon478]

nice job, would have been nice to have adjusted that boost from 3-4 so we could see the gains sans boost increase..

[@Matp345]

Honestly didn't think exhaust played that be a part. And now youe know , and knowing is half the battle

[@minivanin]

as a rule of thumb I like to start at least 1 size bigger then the turbine outlet for a proper effort turbo builds. plus go at another size up if running the wastegate back into the exhaust

[@krakhedd]

By far my single favorite of your videos, I love the science videos. I would love to see how header wrap affects these numbers too, as well as different turbo header/Y-pipe diameters

[@fixyourautomobile]

I liked these videos already, but now that I have my own 5.3 LS 4L80E swapped 2001 Mustang V6 on 10psi T45 ebay turbski, they are better than TED talks! I think I blame Mr. Holdener and Mr. Mcfarland for not so subliminal messaging to the deepest parts of my car brain.

[@andrewlace]

Where'd you find a 4l80e are they rare in the states?

[@michaelenglund4963]

@@andrewlace many 2500 and bigger trucks, vans, and SUVs had them. Pretty common here in Texas but most have been worked hard.

[@andrewlace]

@@michaelenglund4963 in Australia that's the hardest thing, getting a good gearbox. Lots of turbo 700 getting built but a 4l80e would be a fantastic gearbox especially if it's been built. Imagine one of these behind a barra (Ford) lol.

[@reverendlawrence7584]

Thanks again Richard for all the hard work you do for us gear heads great info

[@tomcelica]

Ah you got me. I thought you misspoke when you said more back pressure and less boost equal more power. Ye got me again ye scurvy dog!

[@WDMtea]

Would like to see you test out cut-back turbine wheel. In Japan I used a “T70” on my RB, and had the exhaust wheel trimmed back,

[@johnsheetz6639]

That's a mod I've never heard of before.I think that's very interesting 🤔

[@177SCmaro]

I use a 5 inch downpipe on my s475 because I had the room (some of the firewall had to get out of the way) and that's what the outlet is plus...the huge pipe looks cool. It seems to really like it. Despite having no boost controller and running a pretty small 5L engine, it seems to spool pretty quickly. A 4500 stall doesn't hurt either.

[@pw5668]

I heard somewhere that having a recirculated wastegate, as opposed to open wastegate, improves boost control. But I have also heard open wastegate makes more power.

[@hydrocarbon82]

Recirc reduces the pressure drop across the wg and slightly increases post-turbo backpressure, so it's both less HP and worse control. Nothing earth shattering tho.

[@phrogman4654]

Now you need to do a 3" y-pipe and see if bigger before the turbo helps.

[@richardholdener1727]

THE 2ND MOTOR HAD A 3-INCH Y PIPE

[@bcbloc02]

So essentially if you increase the flow thru the system you increase the power.

[@RDC_Autosports]

it is the most interesting balance i must have done this with hundreds of turbos…. VGT i can keep it 1:1… pretty neat how they work

[@michaelgunning347]

On a recent hp academy interview ( I agree with your point ) but the tuner , the scion guy , stated he seen 0 extra exhaust flow / volume to the turbo adding 100-150 nitrous under boost , where as I would have expected to see this enhance spool with gas expansion, but it seams not

[@richardholdener1727]

he is wrong-how do you add an extra 150 hp to any motor without changing exhaust flow?

[@michaelgunning347]

@@richardholdener1727 so here is a link kzbin.info/www/bejne/oqO8oZqHfr2Gia8 see he is a credible source , see what you yhink , i'm with you on this , might be worth a video , not to prove someone wrong as he seen what he seen , [[ different engine or whatever ]

[@vinnycalvo4148]

Okay so for the daily driver of a heavy truck, can you do a test with an lq4 and 706 heads on 87 octane! Gas is expensive these days! Up over $3/gal for 87 I haven't even attempted to look at medium or high grade

[@luisalmeida6524]

Richard, you seem to make emphasis on the exhaust setup right after the turbo. What would you call that form where there seems to be 2 reducers matched together? Could you elaborate? It resembles a regular yet turbine exit. I imagine there's something there as to the shape air wants to take while exiting.

[@richardholdener1727]

was only there to allow us to bolt it together-not a good idea

[@ProjectCarTV]

10 people didn't make more power.

[@pennysgarage]

Completely unrelated: Richard Holdner now sells exhaust valves and pistons...

[@richardholdener1727]

No Thnx

[@pennysgarage]

@@richardholdener1727 Have you done any work with the Caddy Northstar? I've heard of some great results on the dyno just with some camshaft adjustment with the stock cams. I think it would be fun to check out since you did the big inch Caddy engines. Now you could do the baby Caddy engines or even the 4.0L Aurora engine. Big revs!!

[@crisitanc5666]

Can you make a price range about how much it would cost to turbo the yunkyard ls Richard thank you

[@brandonrohrer7914]

More rear mounted turbo please

[@shadowopsairman1583]

Back pressure impedes on boost efficiency

[@pokebass1]

Hey, you should check out Eric Weingartner on KZbin. He just put out a video called "Appeal to Richard Holdener." He has a really good ideas for a video that I would really like to see myself. He wants to test a ported intake manifold and see what happens when you have a dominator manifold with a clover leaf and take it out.

[@richardholdener1727]

THNX-ALREADY REPLIED TO HIM

[@thomasgjonovich5524]

Love this video. Tells me that I want to do a 6.0 with rec port heads a ls3 or truck intake and boost and a 4 inch exhaust with a electronic boost controller. That to me would be the most efficient set up for a street application.

[@ardennielsen3761]

how many 90 degree bends on the charge pipe till it makes no boost?

[@fixyourautomobile]

Tesla Valve charge pipe! Kickass idea! hello heat soak! We could call it "The Detonator"

[@ToprankImporters]

Turbos are always gooder.

[@anthonycamillos3719]

Richard, I had a read through the comments and it seems like you've upset a few people 🤣🤣🤣 great video btw

[@richardholdener1727]

WHO WAS UPSET?

[@Saddedude]

Boost is a measure of resistance. Rec port let more air in, lower boost Rec port let more air OUT more backpressure As usual rec port is king. ;)

[@jeepramz]

Loved this video. Answered alot questions I had.

[@lindsaydempsey5683]

@Richard can you please put up a link to the other video that you mentioned at 1:48, I'd love to watch that one.

[@richardholdener1727]

EASY SEARCH ON THE CHANNEL

[@robypmg]

ls 5.7 9.5 cr lot of backpressure ( vs racing 7875)...headers or line afrer turbo is the cause?

[@richardholdener1727]

exhaust size and flow after the turbo effect back pressure, so does the na power vs turbo size

[@NicholasKaloi]

Quick question I have a K24 but my throttle body leaks, so I wanted to weld it on in front of the compressor on the turbo housing is this a good idea? I am on a budget, but I can weld.

[@richardholdener1727]

welding the cast throttle body might be difficult

[@NicholasKaloi]

I could also do a custom adapter, i’ve been welding over 20 years I just have never seen anybody put a throttlebody before the turbo. I’ve seen it done with carburetors. Do you think that I’ll have any problems? Not welding or fabrication but performance. Also, thank you for responding. I know your time is valuable.

[@lazylizard6532]

Can I keep my catalytic converters while adding a turbo to an LS1 from a 2004 GTO? Want to stay emissions legal.

[@richardholdener1727]

rear mounts can run like that

[@mr.pineapple7620]

I wonder what happens if you feed a radial supercharger into a turbo and put an intercooler behind both stages

[@richardholdener1727]

we ran twin turbos with an intercooler feeding an M112 Roots on a 2003 Cobra motor with an ATW cooler-works well

[@mr.pineapple7620]

@@richardholdener1727 well yes but I expect a centrifugal to work differently then a positive displacement blower. Hear me out. At low speed the turbo can still suck through the centrifugal. At higher speed the turbo does not reach its flow capacity nor its surge line since the surge line is defined by the ratio of ambient pressure to pressure after the compressor. And the flow cap / choke is defined by CFM in which does not change much since the air is pre compressed. Turbo speed will likely increase but it's counteracted by it having to do more work to compress a more dense charge. So at low speeds you should be able to gain allot more tourque and boost earlyer on and you should also gain more efficient operation at higher speeds (compared to a turbo of the same size at a similar pressure) 🤔

[@SB-vb8ch]

What fuel were these engines running? I presume not straight pump fuel? Would be interested to know what sort of ignition numbers they are running too.

[@richardholdener1727]

race gas or e85

[@jackcurrence263]

The banana-in-the-tailpipe pic got me laughing.

[@dfabeagle718]

Is there any kind of math that can be done to help choose an exhaust housing AR? Let's say two ebay GT35's for a 466 to 521 inch mill, there are two different AR's and I'm leaning towards the bigger AR because it's not a small engine and I'm not clear if the smaller AR (.62 ) will choke it compared to the .80 AR. All the mathy things I find are impeller maps, but that's the other end of the turbo... :)

[@richardholdener1727]

use .80 on a 521

[@slyr1]

What do you think is the best power adder for new mustangs Turbos supercharger or Procharger

[@richardholdener1727]

they both work, they produce different power and boost curves as demonstrated

[@slyr1]

I have a Gt350 with the 5.2 and just trying to research what will work for that allocation

[@turbotrana]

I hold onto every word.

[@bevinsracing]

Richard Erik wienhert want to talk to you about some intake testing that he is willing to supply parts and port labor

[@BEANS-O-MATICtransmissions]

@richardholdner Per your theory, i ask you this.. If a cam that's ideal for an NA engine to make the most/best power it can, then why are there "turbo" cams? From your theory, "the more you make NA, the more it'll make boosted". The conflict i see is, the ideal NA cam for a given engine isn't the best cam once it's turbo'd. Discuss...

[@richardholdener1727]

take a stock cam on a 5.0L Ford-then run it under boost. add an XE274HR cam-then run it under boost. what happens?

[@Saddedude]

N/A cams tend too have more overlap. Turbo cams tend too have less. If you have 30psi of back pressure and 15psi of boost what wins when both the intake and exhaust valves are open?

[@otm646]

Print out the spec sheets for those camshafts and put them directly next to each other. The na cam is working to maximize volumetric efficiency given a pressure differential of one atmosphere max. Your turbocharged camshaft has a broader pressure range to work with trying to fill that volume, so it can be optimized in other ways because of that.

[@CallofDoobie585]

I wonder how westec all started

[@BulliKid]

Is 2:1 a bad ratio? Backpressure to boost

[@richardholdener1727]

VERY NORMAL RANGE

[@BulliKid]

@@richardholdener1727 what if your backpressure if very high. I have a very tight tight 90 after the turbo and I think it’s making a lot of backpressure.

[@richardholdener1727]

restrictions are bad for flow

[@BulliKid]

@@richardholdener1727 yes but what will the restriction and bad flow cause. Other then HP loss. Does it push air back into turbo through the seal? Does it damage the turbo? Does it make it run rich? Does it not evacuate the gasses in combustion chamber causing more pressure on rods?

[@RHBTurbochargers]

Damages your dyno sheets thats about it

[@derekturnbull9046]

When do u plan on doing the dodge magnum engine test?

[@richardholdener1727]

LATER

[@unclesquirrel6951]

@@richardholdener1727 it's been 2 minutes since you made this reply .... so it's now later ..... just saying sir

[@Canadiancarguy1987]

@@unclesquirrel6951 Jeez you are everywhere!

[@unclesquirrel6951]

@@Canadiancarguy1987 lmao I'm sorry sir :(

[@zachadams2695]

Please do a turbocharged 3.4l camaro or firebird engine

[@rickswicegood834]

I agree with this person please do a 3.4 liter 60 degree v6 camaro preferably a 94 model.

[@jonadkins9339]

Richard, quick question. I have an LS1 Trans Am. Has longtubes, LS6 Manifold, still has stock heads it's getting a 227/235 .618/.605 110+3 Cam soon. Would a FAST 92 be worthwhile with my setup?

[@richardholdener1727]

IT WILL HELP 10-12 HP

[@jonadkins9339]

@@richardholdener1727 Appreciate the reply! May pick up a used one!

[@timothysanders431]

I would love to see you play with the eco boost v6 .

[@PureCountryof91]

Those engines can get down..

[@Hello_its_me_mario]

hello there, so im having issues with boost drop with a smaller exhaust system but when i do open downpipe it work wonders. do you think this will be my issue?

[@richardholdener1727]

YOU ARE BUILDING BACK PRESSURE AND IT CAN ALSO CHANGE THE OPENING OF THE GATE

[@joshc5512]

Got boost?

[@Saddedude]

Hey richard id be interested too see a factory valve shootout. Solid stem L76 valves Hollow Stem Ls3 valves Titanium ls9. Measured onna factory gm cnc ported ls9 head.

[@BEANS-O-MATICtransmissions]

The only benefit to the different weight valves is it's ability to resist float and maintain valvetrain stability at high RPM. There'd be no power gain besides that unless something was on the ragged edge and the couple grams made the difference between stabil at 8000 rpm for example or not. For most apps, it's not worth the cost

[@Saddedude]

@@BEANS-O-MATICtransmissions i would be interested in seeing it play out either way :)

[@dennisclanton5342]

Thanks for another great vid.

[@bobbywalter5320]

More great work 👍

[@TubeCarz]

An easier way to say it is : Measuring boost pressure is = to measuring resistance of flow.

[@richardholdener1727]

THAT'S NOT WHAT WAS TESTED

[@b.c4066]

@@richardholdener1727 kzbin.info/www/bejne/a3-2aX2iedKgnpo you have a colleague wanting to collaborate on a project.

[@justinvanburen8259]

Great info, thank you

[@TorquePowerVideo]

I keep reading posts online that chambered mufflers are HP killers behind turbos compared to other mufflers. Any truth to that or is it just more internet folklore? Care to test it if you haven't heard of it?

[@evanarthur7535]

I remember an article with dyno tests saying Flowmasters were 50 hp down vs. Borlas on a 550 hp supercharged SBF.

[@richardholdener1727]

I HAVE NEVER TESTED THAT

[@maybellene500ss]

Chambered mufflers are hp killers period

[@chrishansen7004]

@@maybellene500ss not necessarily any kind of muffler can be a power killer in really high horsepower applications I remember watching a vid about a Cummins that gained like 80 horsepower after removing a resonator

[@TorquePowerVideo]

@@richardholdener1727 maybe that would be a good test session for a future video. I'd definitely be interested in seeing that test on a boosted motor.

[@russelljackson7034]

Right on

[@dr_tate]

Great video

[@uscgamecock9432]

Can you do this with NA LS motors

[@richardholdener1727]

back pressure tests?

[@uscgamecock9432]

@@richardholdener1727 yes. I've got open headers on a stock 5.3 with a tune and all the old guys I work with are telling me I need to put mufflers on it to get more back pressure so it will make more power and I dont see how that makes sense

[@bernie232]

@@uscgamecock9432 old people think back pressure is something you need, it's an absolute load of shit. Get your car tuned and it will run better, it might run a little lean with open exhaust.

[@rickrack78]

#5 is alive!

[@glockmodder]

NO DISASSEMBLE JOHNY 5 is alive!?!

[@rickrack78]

@@glockmodder 😂

[@curvs4me]

Richard, can you add the lobe separation of whatever cams you are running at the time so we can see examples and where peak torque happens. It's more significant with carbs because you can't vary injection timing or duration. 106 separation has a lower peak torque than say a 110 lobe separation. Obviously with EFI you can do whatever, I'm curious to see what the effects are.

[@richardholdener1727]

cams do the same thing regardless of whether the fuel is supplied by a carb or efi

[@hydrocarbon82]

I've always been puzzled by why you don't use that fancy boost controller more, today it got me thinking. Do you do it because that many people run off the WG spring? Unless you've absolutely maxed out your turbo or fuel injectors, or have no more traction, there's zero reason to run gate pressure with less HP than your rods/pistons can hold or cam/heads can flow. Otherwise it's basically like saying "gee, I think I'll run half a second slower for no good reason today"

[@nordic5490]

Although... it is recommnded to run gate spring pressure that will give a boost of about half you final target boost, for best boost control. Eg, run a 12psi spring if you intend to run at 24psi, and let your controller to do the rest.

[@richardholdener1727]

do you think that every turbo owner runs around with their turbo set up on max boost? on the street? the answer is no-most run around at lower boosts and only set them on kill for track use

[@scotttimpany2845]

Five inch exhaust

[@richardholdener1727]

at least

[@unclesquirrel6951]

Personally I blame squirrels

[@BEANS-O-MATICtransmissions]

Woah ! Woah ! Woah ! That's some John Woodworth shit right there ! Take it easy bro.....

[@curvs4me]

The LS3 heads need a bigger A/R to drop the backpressure and increase the boost pressure without changing anything else.

[@richardholdener1727]

any head that increases the power will show similar back pressure results