LS TURBO EXHAUST TEST-THE DOWN PIPE DILEMMA-WHAT SIZE WORKS?

[@SloppyMechanics]

its interesting to see the pressure changes are not significant but the power numbers are, something to think about for sure

[@GonzosGarage]

Wonder how the back pressure numbers are affected if he had an electronic boost controller maintain consistent boost pressure! 🤯

[@GonzosGarage]

I remember a video of yours awhile back when u said boost is basically measurement of back pressure before the valves NOT air flow and that has stuck with me.

[@TheDude2111]

@@GonzosGarage I agree intake manifold pressure is a result of restriction in the intake side and can be better demonstrated using a supercharger and going from lower flow heads to higher flow heads. Keeping all pulleys and equipment the same. This usually results in better power with less boost. Psi is relative to input and restriction but cfm is simply air flow.

[@SloppyMechanics]

i watched this with budos band in the background, fantastic

[@juiced71]

Sloppy Mechanics you smoke weed by chance? Lol that whole mr Rodgers thing of the land of make believe 😂😂😂

[@divafizz]

I just bought an LY6. Thank you for your diligence and testing. Two thumbs up!

[@richardholdener1727]

LY6 FTW

[@jaymewininger7035]

Everyone-power secrets Richard-im just going to give everyone bang up content!! Everyone- that's the sh**s I like!! Great video man

[@richardholdener1727]

Richard-Here is cool free content. Everyone-You didn't use mufflers and used the WRONG Cam! LOL I want and learn from every comment-good, bad or indifferent. This is an adventure we are all taking together.

[@jaydubb71]

The best exhaust for a turbo is none. And this test proved it. Thanks for the video!

[@jaydubb71]

I've been telling this to folks for years

[@700HpVette]

Until you have oil blowing all over your tires or windshield...

[@jaydubb71]

@@700HpVette True. I would never run fenderwell exhaust or anything. Straight pipe, no muffler...

[@jessemurray1757]

Another great technical video bud. I miss the days of getting a new issue of car craft, hot rod, etc and seeing the dyno tests they used to do.

[@richardholdener1727]

we might still do them-just be digital

[@nellyfarnsworth7381]

Do they still print Hot Rod???

[@fivepointeightnate]

I wish you were making videos like this 12 years ago. Would have saved me many hours and $$$!

[@barrywilky535]

Thanks Richard! Every little bit of knowledge helps.

[@scottgarmon4865]

I built a C5 for a customer with TTi turbo kit with twin 60s and it picked up 100rwhp with cut outs over through the stock titanium mufflers.

[@Kj16V]

What are cut outs?

[@cleveland2286]

@@Kj16V valved mufflers. Cutouts allow you to bypass the muffler on demand and make it a straight pipe until you close the valve again.

[@tunerdadtunerdad7927]

Excellent test. Thank You for your work and enthusiasm. Makes me feel good about my 3" DP on my 4.8 coupe. Thought I was giving up alot

[@nellyfarnsworth7381]

It's just a 283 cid. 2.5 " would be GOOD.

[@tunerdadtunerdad7927]

@@nellyfarnsworth7381 I dont think so...I would never go smaller than the turbine outlet.

[@nellyfarnsworth7381]

@@tunerdadtunerdad7927 I was thinking about N.A. & Dual pipes. I have some questions. I have a Gen. 3 corvette. Want to pull the engine out & replace with a L.S. 5.3 Liter, naturally aspirated. Tell me about your engine, horsepower, torque, m.p.g. & price (with turbo). Did you tune your engine??? Thanks.

[@MJTAUTOMOTIVE]

Thanks once again for another great video Richard. 👍

[@ryanaxberg9263]

just came across this channel and it is right up my alley. I would say that if you keep this up you will have a pretty good following soon

[@richardholdener1727]

thnx-now go tell all your friends-you have a couple 100,000 close friends, right? I love testing and bringing the info, even if it's just me and a couple cool guys watching.

[@jameseaston1329]

turbo response is related to exhaust velocity before the turbo provided the down pipe is big enough. Nice test. This proves i built mine right. :)

[@markrich3271]

Richard Holdener You know you can run air to the top of the waste gate only if your having back pressure problems or changing the housing size reduces back pressure also. Im sure you know this but figured ide mention it. Love the videos.

[@177SCmaro]

s475 on a 5.0 Coyote I plan on making around 750-800hp. Turbo comes with a 5in outlet so I'm running a 5 inch downpipe even though a good bit of firewall is going to have to get out of the way. I like to keep things simple, lol.

[@argometertzar1275]

the more i watch his videos the more i like it, keep up the good work man

[@brandonpanozzo86]

heck yeah early morning boost with the info finder you are the man richard

[@havarbeknutsen2428]

very interesting. can you continue to test compound turbo? I consider building one for my car and want more info and technical data :D nice worke

[@jeffmatas4060]

Another great test Richard! Like you said, it would be interesting to see the power difference when you’re closed-looping on a target boost pressure. Your calculations on those results seem reasonable.

[@1999ekk24]

Hey Richard as great as this test is I think it could be be redone for your viewers enjoyment. It appears the 3 and 3.5 inch exhaust was connected to a dump pipe that went from 4” off the turbo to 5” then reduced down to the exhaust size. A bigger dump will benefit the smaller exhausts largely. It’d be great to see full length exhausts or even 1-2m of 3 vs 3.5 vs 4 straight from the back of the turbo. You also say a 3inch would be better on a 600hp car, that is incorrect. If you add your electronic boost controller you could test all 3 size exhausts at different boost/hp levels and that would be a great informative video. Thank you for all your work, it’s definitely the best car related KZbin channel I know.

[@StavTech]

In my experience, the results would've been MUCH worse if the 3in and 3.5in was that size from the turbo back, but for the first 12in or so after the turbo, the most important part in my experience, they were BIGGER than the 4in one! Looks like they coned out to about 5-6in before going back to 3-3.5in, where the 4in was just straight pipe.

[@thomasgellos1732]

Coned out as to do what to the down pipe?

[@C6Z_Bob]

Awesome test, Richard. I'd really like to see a similar test with an NA engine with a y-pipe to a single exhaust. Unfortunately most of the options for us 4th gen Fbody guys are y-pipe set ups. That would be awesome to see how much power is picked up going from 3" to 3.5" to 4" on a cammed LS.

[@exploranator]

It would not be as significant, because post-turbine flow is far closer to being constant, and constant flow benefits from an infinite-cross-section exhaust pipe. Pulsed flow benefits from a cross-section that utilizes the velocity of the last pulse to create a lower pressure area behind it for the next pulse. A single-pipe exhaust receives eight times as many same-size pulses as a single exhaust header primary tube, so it has to be larger in cross section for two reasons: higher frequency, (8X the frequency) and greater overall volume (8X the volume) of an exhaust primary tube, BUT, the change in pressure between each peak to each trough in the pressure waves is far smaller than right behind the exhaust valves.

[@BulliKid]

Great video. On my boosted civic I noticed more boost pressure with open downpipe vs oem muffler.

[@richardholdener1727]

YES-MORE EXHAUST FLOW IS BETTER WITH A TURBO

[@WhyNot6243]

The other thing is the pressure difference across the cylinder. This is where the power more than likely came from. You had 11.7lbs boost and 19lbs back pressure with the 3”. Resulting in a pressure ratio of .615:1 then with the 4” exhaust you had 12.7lbs boost and 18lbs back pressure resulting in a pressure ratio of .705:1 this essentially made the cylinder more efficient and allowed more oxygen in allowing more fuel to be burnt.

[@cleveland2286]

I was thinking of this as well. Since his power went up, well that also means he's producing more exhaust gases. Likely why his backpressure numbers weren't THAT different yet made huge differences -- all of that pressure decrease goes straight into making more pressure.

[@damianscheuber1603]

Would be interesting to see what would happen if the wastegates were plumbed back into the dump pipe. A lot of the exhaust flow it just going straight out of the wastegates.

[@nelsonperez9385]

keep em coming man these videos are so informative

[@nono-fn3zc]

Why not try 5” to see if there’s diminishing returns beyond 4”? Maybe future update?

[@EastsideDonkey]

I would like to see a 5" full exhaust with muffler.

[@700HpVette]

What you need is already in this video...

[@srvdean3024]

Because that's bigger than the turbo outlet.

[@otm646]

5:58 shows you the diminishing returns. Use those three data points to infer the 5" result. It's going to be a 0.1 to 0.25 PSI max drop from the 4 inch.

[@grumpysteelman]

SRVDean - I actually put 3” and sometimes 4” down pipes on internally gated 15G turbos on Volvo cars. The outlet was around 2-1/4”. It made a difference.

[@jedt4433]

Hey Richard, I would like to see a test not only on spool time (response) of reducing the primary and collector, but also log style vs. Header with back pressure and spool as well as top end power. I have read many times that reducing the primary on 6.2 LS and smaller down to even 1.625” and collector to 2.125” or 2”, increases pressure and velocity, creating faster spool, while also allowing you to increase the A/R to Maximize top end exhaust flow. This is all concerning the hot side before the turbo. This all makes sense in theory and people have tested it but I don’t see actual dyno results posted.

[@richardholdener1727]

lots to talk about there

[@shannonsisk]

Good info that a lot of people wondered for sure. I wish there was a 5 or 6 inch exhaust test. I have a 3” outlet on my turbo opening to a 4” down pipe. I’ve always wondered if it helps/if it’s worth the weight

[@jeffschwartz5199]

Boy , that was a lot to ingest ! Thanks man , I needed that ! 🍺👍👍

[@Turbogto_guy]

I have a great idea for Dyno testing. Test 2.5” and up charge pipe on a 900hp turbo setup along with stock size and up throttle bodies. That would be very very interesting! Some people think you need a big throttle body and I just dont think you do.

[@richardholdener1727]

This had a stock TB size and LS6 intake opening. Obviously they are less restrictive under boost. But charge pipe diameter and EXTREME length would be good tests.

[@B7_S4_Turbo]

​@@richardholdener1727YES that test would be interesting!

[@sprintcardriver8]

You should do a comparison efi turbo ls vs a blow thru ls Super Victor intake and a good blow thru carb

[@lukeschannel650]

Keep em coming Richard

[@Turbogto_guy]

As I was watching the video, I was thinking, what about the added boost? You have to factor that. And you did at the end. Good shit! I went from 3” to 3.5” a few weeks ago and couldn’t tell any difference at the same boost level. So this reinforces my butt Dyno. 😜

[@hydrocarbon82]

Ditch the bleed-style MBC, get a hallman-style that blocks boost. They are literally a pressure regulator and are better for nailing repeatable boost with different backpressures. Also there's virtually no boost leak. IMO the only time comparing based on backpressure effects is when it's absurdly high and something is being maxed out.

[@pwilly7]

Not surprised by this at all. This is why log manifolds on daily drivers is a PITA. Running a 4” all the way back can be tight. Running 2 3” is easier.

[@daleostrom3613]

Richard, I got a problem with this test. You have a oval muffler on 3". You have a bullet muffler on 3.5" You have no muffler on 4". So I believe the muffler, or lack of, is responsible for this situation, not pipe size. Would have made a lot more sense to put straight through bullet mufflers on all ???

[@BadAssEngineering]

The real MVP here is Flow: Any Engine is an Air Pump. I dont know how much more CFM you gain with going from a 3" exhaust to a 4", but my educated guess is that there lies the answer

[@GonzosGarage]

Wonder is there is a way to measure the cfm out of the exhaust during the pull.... 🤔

[@jacobburskey3044]

I think you should do the same test on a smaller motor too, to show if the 3in is actually adequate on say a 4.8 turbo engine! I think the larger downpipes will still show gains, though probably not as big

[@richardholdener1727]

Jacob Burskey the exhaust flow after the turbo is more about power out put. If the 4.8L is run up to 900 hp, we should see the same gains. The difference might be the back pressure curves before the turbo

[@ReubenHorner]

I saw an interesting one on facebook of all places where a tuning shop saw improvement in spool as they increased the size of the first section of downpipe well above the side of the turbine outlet (6 inch I think is what they go to).. I believe the change is because the air coming from the turbine wants to spiral outwards where the downpipe is straight.

[@jessemurray1757]

Heres one for ya. I gained 30 wheel going from a stock catback 2 3/4" with flow master muffler to a 4" cutout on my old NA LS1 Trans Am making only 450 wheel.

[@richardholdener1727]

that is a lot

[@jessemurray1757]

Richard Holdener yessir, so it’s no surprise to me that an engine making a lot more power gained even more. We will be testing this on my buddy’s turbo camaro. He currently has a full length 3” catback and is going to a 4” cutout. I’m expecting at least 60 wheel. While we’re on the topic, I tested a 500 wheel HCI NA LS1 that had the 3” borla catback. He had a cutout setup to just bypass the muffler and exit the passenger side tip instead of going through the muffler and exiting the drivers side tip. It picked up 8 wheel by itself. Whenever I see anything making over 400 wheel, NA or not, running a single 3” I cringe. I’m still really interested to see a single 4” to dual 3” comparo btw.

[@richardholdener1727]

@@jessemurray1757 let me now

[@jessemurray1757]

Richard Holdener will do but won’t be till spring.....Michigan

[@shaadydog1]

My man love this, wondering if you could go over open/divided turbine. The benefits, drawbacks and how to utilize them with your header/manifold.

[@richardholdener1727]

shaadydog1 Id like to test some divided housings and dedicated y pipes, right now I just mix and match

[@yeetskeetledeet8184]

Awesome test. I’d love to see this same test run with a maxed out turbo. By that I mean bring the boost up with a 3 inch exhaust until the turbo reaches max efficiency and the motor stops making power with increased boost. Then the same with 3.5 and 4.0. I’m guessing that the exhaust with a higher back pressure drop across the turbine will have a higher efficiency limit.

[@richardholdener1727]

Jordan Breier a higher power level will show greater gains with the bigger exhaust

[@yeetskeetledeet8184]

Richard Holdener gotcha, thanks Richard

[@lindsaydempsey5683]

Something that I think would really add to this story is to look at where in the rpm range where boost pressure equals turbine inlet pressure. Engines love turbos, but they especially love turbos where the inlet MAP is higher than the exhaust MAP. In that regard the point where that pressure cross-over where exhaust pressure starts being greater than inlet pressure is a great health indicator IMO for the set up in terms of turbo match and restrictions in the inlet and exhaust systems. If a change in external combination moves that cross-over point further up the rpm range, that should normally show very good gains in HP and I think that's a big part of what happened here with the increased exhaust size post turbo. If you haven't done a video explicitly looking at that cross-over effect as the main topic, I think that it would be a good one to do. Keep up the great work :) PS: I used to work on large 2 stroke marine diesel engines for a living as a marine engineer. When in the working load range, inlet pressure was always higher than the exhaust pressure, so much so that these engine did not need any external scavenging aids like a root blower or under piston scavenging, an apparent miracle that always impressed me.

[@richardholdener1727]

RUNNING LESS BACK PRESSURE THAN BOOST PRESSURE IS NOT HARD-IT DOES LIMIT RESPONSE THOUGH

[@EricErnst]

I've got a 74hp diesel concrete saw with a bad muffler. Time to upgrade to bigger exhaust.

[@kbracing96]

I think you just need to run a 3 or 4 port MAC valve and set the holley up for closed loop boost control based off MAP. That way you always have the same targeted boost for all the test.

[@EvanAxer]

Hey Richard there is one test i would love for you to do and see if there is any significant differences in Turbo Location so basically Turbo at the headers vs a "rear mound turbo" which would have headers going into a Y pipe to a length of pipe to the turbo then turbo to a muffler. It be nice to see turbo response, exhaust back pressure, turbo temp and air temp before the IC.

[@richardholdener1727]

please see the remote turbo video

[@EvanAxer]

@@richardholdener1727 hah god damn Richard you are one quick dude. Keep up the great work!

[@philbetthauser9547]

Excellent test. In your option how much difference would there have been if you used the electric boost valve?

[@richardholdener1727]

Phil Betthauser as indicated in the vid-25 hp or so was due to boost-35-40 hp was from the exhaust

[@philbetthauser9547]

@@richardholdener1727 Thanks. I missed that.

[@prozeke07]

Intrigued why the 3" back pressure was so low... in comparison track back pressure on my setup 7875 5.3l 3" similar to your test but was at 5-6# back pressure till I went to a loudvalve cutout at turbine addition to the 3" exhaust dropping back press to 0-.5#. Again odd for a larger turbo and engine to have less BP in the 3"

[@alloyspeed1889]

Very interesting results with around 5% variations. Soooooooo will a 5 inch short straight section off the turbo be the standard measurement?

[@srage9188]

😺Good looking out Richard.👍

[@nanospeedandchrome2259]

I don't get why they don't build turbos with tapered bearings so they can be pancaked onto A/W intercoolers (on top)... instead of having to always set them up with gravity in mind. All the plumbing could line right up (how well would a "downpipe" work, if it was straight up (and just long enough to nicely clear the hood) and exactly the size of the outlet, to start?). Make it adjustable, and (if supplied with plenty of clean oil) run 1 set of quality bearings for life. Took a few vids to get used to your delivery, found it to be quite efficient... subbed.

[@oldleatherhandsfriends4053]

The bearings would fail from the rpm,load, and heat. Turbos ride on oil film like engine bearings.

[@CosmosMBTS]

LOL, You will probably still have people telling you you need back pressure on a boosted engine! I gained 29rwh, I went to a twin 2.5" out of the headers to twin 3.0" to the bumper, on my supercharged 3liter 6cyl - and I lost about 2.5psi boost in the process. (less boost more hp and tq) Oohhh.... the experts that came out to say you will have no back pressure... you will loose HP.... Etc, etc... Good to see some people getting the correct info for their boosted engines. 👍

[@177SCmaro]

Yes, you made more power with less boost because you removed a restriction. You can do the same thing with a cam change. A lot of people don't understand that and don't realize or forget that "boost" is backpressure between the compressor and the engine - a byproduct of what a supercharger actually does, increase air density.

[@jaydunbar7538]

Higher boost pressure also comes with higher heat, heat is the devil.

[@timcampbell5141]

How about a video comparing the same turbo but with different sized turbine housings.

[@bcbloc02]

Now we need to see turbo log manifolds vs equal length headers. But to make it a good test they both need to flow about the same. Question is does exhaust runner length pre turbo effect power and if so how? I have always felt the shorter the better. Reduce lag, improve low end performance and not give up much if any on top. What say you?

[@tunerdadtunerdad7927]

So...was thinking a little more on this subject. How about a test on different exhaust housings? How much do you really give up on say a 76/75 with a tiny .81 up to whatever the biggest they make is, or so. Doesn't have to necessarily be that turbo, but I'm sure you get the jest of it.

[@richardholdener1727]

I ran AR testing on a Honda back in the day-it makes a big difference when you get near the max flow of the turbo

[@MrTommy954rr]

Was the mufflers on the 3” and 3.5” open throat design? And why no muffler on the 4”? And they wasn’t equal length.

[@troymecey]

This was my question also. Would like to see the 3 and 3.5 run with a short pipe and no muffler , just like the 4. Not an apples to apples comparison.

[@richardholdener1727]

Tommy954rr 4 inch was the race exhaust

[@MrTommy954rr]

Richard Holdener OK I understand now. Some what stock full length to a modified before axle then all out fender exit.

[@richardholdener1727]

Tommy954rr yes-just simulating different Exhaust configurations and showing changes in pressure and power

[@ChadLisonbee]

Bravo sir!!! keep’em coming!

[@richardholdener1727]

will do

[@williamzoom]

I'm not going to fall for a banana in the tailpipe! )

[@boosted_redrum_ram705]

Awesome video. So my set up is a Ram 1500 with a built 6.4L/392c.i. Hemi with a VSRACING 80mm/t4, E85 etc. We decided to run full exhaust, necked it down from 4in to 3in (for clearance between frame and firewall) with a race muffler, all the way back to the rear of the truck. Planning on putting 16psi and hoping for 800+whp, so we shall see if it works or redo all exhaust to 4in or just do fender exit lol. It’s kind of a sleeper truck for now 🤷🏻‍♂️

[@Fackler91]

Great video

[@jplperformance9073]

Love the channel

[@ilostmymindcom]

My girlfriend said "That math is exhausting!"

[@s4060]

how does she talk with her mouth full?

[@mlwakat]

Id love to see this same test with twin turbo LS

[@richardholdener1727]

michael wakat Twins would work well with 3-inch-each turbos is only flowing 450 hp

[@danielsullivan9865]

Me to we run twins 69s picked up 300 rear-wheel horsepower. by changing AR from .91 to .96 on 24 lbs of boost it went from 788 whr at 5000 RPMs to 1030 whr at 6300 RPMs. 3inch exhaust would 3 1/2 make a significant change in power output?

[@richardholdener1727]

Daniel Sullivan that seems like a big change in power for a minor change in AR-glad it worked for you

[@exploranator]

It would be interesting to see a truly titanic exhaust system post-turbo. Start with a 6", then go to an 8" then a 12," but the caveat is that you have to flare out smoothly from the turbo turbine, because that 80,000 RPM air is wanting to fly outward when it leaves the turbine housing from centrifugal force. For more real-world-ish numbers, make the exhaust pipe post-turbo about 10 feet long. Also, the 4" had no muffler on it, so that would help, of course, but the takeaway from it is that NO exhaust system at all may be ideal for after the turbine. I would have liked to see THAT. In constant-flow, which post-turbine flow is, largely, compared to the super-pulsed just-post-exhaust-valve flow, the rule is that the larger your conduit, the lower your resistance. And, the whole "correct backpressure" fantasy: the "correct backpressure" for any piston engine is ZERO, deep-space vacuum, none, not a single atom of air. THAT is ideal. No amount of exhaust going down any length of header primary at any velocity can match the scavenging effect of an exhaust seat that has a complete deep-space vacuum on the other side of it. No port, no nothing, just exhaust seat and perfect, infinite-space vacuum.

[@richardholdener1727]

INFINITE SPACE VACUUM?

[@exploranator]

@@richardholdener1727 Yes! that is the desired net effect!

[@postmortemspasm]

Everyone only talks about size of the exhaust, which is important, but no one ever talks about the length of the exhaust. More length = more friction and my theory is the length of the exhaust is more important than the width. Would be cool to see it tested, i dont think its been done before

[@richardholdener1727]

the length does decrease flow and the length after the header collector also has a tuning effect

[@postmortemspasm]

@@richardholdener1727 would love to see a comparison of exhaust lengths!

[@watsisbuttndo829]

Not turbo specific but i come from a motorcycle road race background and header length was critical. But surprisingly as long as cross section was maintained ,shape didnt matter much. We would have exhausts pretty much straight pipes while we fiddled with length but once that was decided we would package it on the bike, sometimes with some radical bends, but it would work ok.

[@jhonarias2600]

Love it!!!

[@MrZaine97]

I’m pretty sure different exhaust set ups are different for motors with turbos. I have a inline 5 turbo and I absolutely love the 3”straight turboback exhaust on my Volvo. Had a lil low end but extreme top end power with a stock tune on my S60

[@richardholdener1727]

EXHAUST SIZE MATTERS MOST AFTER THE TURBO-BIGGER IS BETTER

[@MrZaine97]

@@richardholdener1727 THANKYOU FOR THE INFO SIR BIGGER IS BETTER SIR!🪖🎖🍻

[@kevinwest3689]

With this information I'm surprised you don't see more rear mount turbos on street driven turbo. I don't know of a downside to it from testing I've seen. What am I missing ?

[@richardholdener1727]

see the remote mount turbo test

[@debbiehipsher3855]

Plz keep these coming sir. I love to learn about this stuff

[@Miladoluz]

Hello, you seem to know a lot about turbos! That's really great! Congratulations! I have a question for you, if you can help me. My car was changed from turbo to a larger one, Borgwarner has a catalog for upgrade (K03) Peugeot/Citroen/mini, they mention "plug and play", however they don´t mention anything about the "problem" that I have. The compressor turbine (which receive de hot gases) turns orange when I barely demand full gas in 5 minutes later. Is it normal? I do not want to touch the ECU, because there are no good professionals in my country. I was told that one way to solve this issue, if it wasn´t normal to have the orange turbine so soon, do I have to change and buy a high flow catalyst as the best solution? I appreciate any guidance on the subject. Regards!

[@nkknico]

AFR

[@ekess7458]

Please run a test on the dorman truck manifold that looks like a copy of the fast intake.

[@richardholdener1727]

ekess7458 I’ve already tested that intake

[@ekess7458]

Ive tried to watch all of your videos but haven't seen it. Part number 615-183

[@richardholdener1727]

@@ekess7458 there is not a vid up yet on that

[@nosnerd1967]

GREAT VID !

[@turbocel4482]

Run the 4 inch exhaust at the boost pressure the 3 inch exhaust made and compare

[@cambilt1683]

I have a 4.8 with a 3” from turbo back full exhaust with muffler and a cut out in front of the muffler. Seat of the pants test says it pulls way harder with the cut out closed.

[@blue_dream_steam]

Still need to compare 2.5 vs 3 inch pipes feeding the turbo. I think 2.5 will spool quicker and won't lack on hp because turbo

[@richardholdener1727]

I don't think there will be any difference

[@jivantakirstenpillay6128]

Nice video. I have a question about this. On my small turbo Suzuki Swift Sport with a TD02, i have upgraded by downpipe from 42mm to 63mm but noticed a flat spot between 2 - 3k rpms, even after loading stage 1 file. In the higher gears 4, 5 and 6 it almost feels like boost lag, whereas previously in stock form it had loads of low down torque in any gear. I know you say with turbo downpipes bigger is better, but does the same apply for small, stock turbo cars ? Or, does it need more fine tuning on the software side ?

[@richardholdener1727]

open exhaust after the turbo improves response-sounds like a tune problem

[@terrycarter8929]

If you put an expanding pipe at the outlet of the turbo you get a low pressure area and more air flow. No more than a 12 degree angle or you will introduce turbulence. I think you should use the piece you had on the first two pulls and put an exhaust pipe what ever size it opens up too. 6"?

[@Crysmatic]

you've got Bernouilli backwards. flow will slow down as area increases, and pressure goes up. Ideal expansion is 8 degrees. I'd like to see the effects of varying length megaphones too.

[@terrycarter8929]

@@Crysmatic pressure decreases as it expands using Boyle's Law. There is a formula for the ideal angle of expansion. I forget but it has to something to do with the diameter times a certain multiplier of like 2? I took photos of the training video but my phone broke. Lol. Think of an orifice in an air conditioning line. Pressure builds up before the hole and the pressure decreases as it expands into the pipe on the other side. Bernoulli's principle is for a Venturi. I worked for Honeywell and they own Garrett. I was able to get to the training videos. It said no more than 12 degrees of expansion or you will induce turbulence.

[@terrycarter8929]

@@Crysmatic in a Venturi the same amount of air flows through the tube. The velocity speeds up in the necked down area and slows back down as it expands. The higher velocity creates a low pressure area at the necked down area. That's why airfoils ( airplane wings)create lift. The velocity over the top of the airfoil has to be higher to reach the other side at the same time as the air that goes underneath.

[@SimonWorlds]

I think you have missed a crucial point, cylinder scavenging and blow down, it is more associated with the manifold, but it still is affected by post turbo restrictions.

[@makantahi3731]

on 300c ,5.7 hemi with 6.1 cam, i replaced cat back pipes from oem 56mm(2.2in) OD to 70mm(2.75in) OD , can i expect some gain(no cats, free flow mufflers, resonators)

[@richardholdener1727]

YOU MIGHT SEE SOME WITH THAT

[@nsboost]

Call turbo smart and get them to send you some of their new electronic wastegates!

[@richardholdener1727]

Marty and the gang at Turbo Smart are awesome! I'll give them a call.

[@anomamos9095]

Log manifolds vs shorty vs long tube vs tailpipe mount turbo.

[@buiItnotbought]

www.dragzine.com/tech-stories/dyno-testing/turbo-manifold-dyno-test-cast-manifolds-vs-tubular-race-headers/

[@theguy9234]

My twin turbo 300zx created boost sooner, when the aftermarket exhaust axle back section was removed.

[@jaydubb71]

@richard Holdener can you do this with the 3/3.5/4 inch full exhaust with no muffler?

[@dilsher12]

Can you test how a LS9 cam works with a turbo since its really cheap at $100-150 , idles like a stock cam @500 rpm and perfect for a daily driver. I know its gives up low end torque with the wide LSA but that doesn't matter once you are in boost .

[@richardholdener1727]

i have tested that a bunch-it's not great but certainly works well for the price-better than the stock LM7-at least on the top end

[@dilsher12]

@@richardholdener1727 I had a 231/231 LSA115 over 6.00 lift in a gen 4 5.3 with a S475 , didn't like it for daily driving . Put a LS9 cam that I had laying around , like it much better and honestly i can't tell a difference from seat of the pants the fueling didn't change much at higher rpms I actually had to add a tiny bit of fuel . Never been on a dyno or track so can't compare .

[@richardholdener1727]

@@dilsher12 i haven't had much success with single pattern cams except for low duration torque cams

[@2ndshiftgarage248]

I’d like to see this test with the waste gate pipe returning to the down pipe and not

[@richardholdener1727]

won't make any difference-just noise

[@camscustombuilds]

Looks like 2.5, 3.0 hotside? Thoughts on 2.25 or 2.5 hotside? From what I've read, 2.5 can handle over 2k hp. Curious if 2.25 is adequate as alot of crossovers and manifolds (log type) are that size.

[@richardholdener1727]

camscustombuilds it’s 2.5-but I’m sure the 2.25 would work just as well

[@dilsher12]

I am running a 4inch exhaust but it's a full exhaust with two straight through mufflers , wonder how much of a difference that makes .

[@jaydunbar7538]

It's all about keeping the exhaust gas hot, if your worried about it you can Amazon yourself some exhaust wrap and do the first 3 feet after the turbo. Keep that temp in the gas and it will help keep the exit velocity higher.

[@bradclary7463]

I have a Ford 363 that was built for boost. Only 8.5 CR, going in a 68 Mustang. CXRacing has a turbo kit for my car. It's 3" leaving the turbo. Do you think this would be good? I still want dual exhaust. Would I connect the 3" to dual 2.5"? Thanks.

[@richardholdener1727]

that will work-depends on the turbo size and power level

[@bradclary7463]

@@richardholdener1727 It says it supports up to 600 whp. If true, that's plenty for me.

[@billbraski2175]

I got some free 5" semi exhaust. Will that work on my next gen 78 75? Or will I loose power

[@jonathanmoore5929]

Please redo test with electronic boost controller

[@juliomorales5686]

More flow = less restriction= lower boost and the same or higher HP

[@2manyprojects689]

Did the muffler's restrict the exhaust output? I noticed that on the 4-inch you did not have a muffler?

[@richardholdener1727]

length, size and muffler

[@EGGINFOOLS]

No muffler on the 4 inch?

[@bradwinsor9677]

What about if the turbo outlet is a 3 in? Would running a 4 in be beneficial? My turbo is a 78/68 turbonetics on a 5.3. Works ok but am I leaving power on the table with running a 3in exhaust?

[@richardholdener1727]

yes if you are maxing out the flow of the turbo

[@sseibonnevilleman]

What I see is 1 pound of back pressure results in the opposite of 1 lb of boost. Not exactly but close.

[@812drmalibu]

First like first comment woohoo!! Keep the information coming Richard great content

[@richardholdener1727]

Gear jammer520 nailed it

[@prestonedmonds4128]

I have a question about the ring gaps. What are you gapping these LS's to and what do you torque the rod bolts to when reassembling the rods?

[@richardholdener1727]

Preston Edmonds gap to .030 and factory angle torque spec or torque equivalent

[@prestonedmonds4128]

@@richardholdener1727 thanks Richard. Do you reuse the rod bolts or get new?

[@richardholdener1727]

Preston Edmonds I reuse

[@johnolsson3997]

How bout use a 3” turbo to 4” down pipe?🤷‍♂️

[@richardholdener1727]

yes

[@davidruff8749]

So why the different lengths and only the 3 and 3.5 have mufflers? I know theyre probably straight through mufflers but still

[@richardholdener1727]

street vs race-not test of cat backs

[@davidruff8749]

@@richardholdener1727 fair enough. Was kinda hoping to see if i could apply this to my diesels.