Fatfrii

iv been talking to some older more experienced car builders about performance exhausts and they all point to venturi collectors for the best performance. Seems correct in terms of physics but in simpler terms you can think of the exhaust as a garden hose and when you spray 2 right next to each other in the air and the stream will travel farther verses the pressure of each hose individually. that's the best simple explanation i can come up with. For those who really don't understand exhaust im comparing water to the speed of the exhaust pulses. I was told that true duals are a myth for creating the most power and i was kind of shocked after all i have read about them here on AZ. anyways just wanted to bring up a discussion and talk about it.

here is a link to some statistical data that i found and and explanation of how it works http://www.headersbyed.com/hc_ventext.htm

KzooTL

Heres some related reading

http://www.epi-eng.com/piston_engine...technology.htm

pohljm

Not sure how relavent it as as we have cast exhaust manifolds that already collect 3 cylinders each without any omptimal lengths etc. so the pulses are already collected haphazardly. Would be nice to be able to have true headers ala 2nd gens.

Fatfrii

^the theory is relevant it can be used in several different types of applications. i our case since we dont have headers, it would be best to apply this as a down pipe (replacing the j pipe)

i know for sure at least one person on here (sonnick) has messed with the venturi diagram

pohljm

you have two pulses that are comprised of three random pulses each, the best you can really do is equal length runners on a j pipe.

Fatfrii

by that do you mean the primary pipes or where the 2 pipes merge?

Sonnick

Ah, another brave soul seeing the light at the end of the Venturi tunnel. There is plenty of verification that venturi's or "megaphones" DO work. Almost every open header setup you will see on a race car has some kind of venturi/megaphone. All the 'custom' header(s) on the RSX-s/Si, etc have the same idea implemented. There is a reason.

Now...they only really 'work' if scavenged correctly. What this means is, primary pipe length is very important as is cam overlap. I don't remember the exact explanation to be honest, but too much overlap is bad and will cause you to lose power. It's a balance that is usually calculated. I just went for it and it seemed to work out. I got lucky

Although we don't have traditional headers, our exhaust still travels in pulses. I will say that we probably won't benefit as much as say, the 2G TL because they have headers. But at the same time, if the exhaust pulses are met and pushed through the venturi, I can't see why it wouldn't work. I gained 15whp/tq from a different Jpipe, venturi collector, 3" exhaust, and UR pulley. I'm pretty sure the pulley makes little to no power on the dyno and most Jpipes really "peak" about the same, only major differences are throughout the powerband. So I attribute most of the gains to the collector and 3" exhaust. I honestly wasn't sure if I gained much from the collector, but the dyno shows otherwise.

I got mine from SPDexhaust.com if you are interested. They do great work. Mine looks flawless. The only 'issue' is because they are really "header" collectors, the pipes are welded so close together that it was tough to get them to fit over my Jpipe. The shop had to 'tack' weld it only because they wouldn't be able to weld all the way around. Other than that, I think it's a great piece.

Atlas.46

Sonnick which one did you get? I see there are 3 different angles. Also if you dont mind me asking how much was it?

Sonnick

I got the lowest angle (12 degrees I think?) and the 3deg taper. I believe it was $220. It's not cheap, but according to the dyno, performed very well.

Keep this in mind though: With each Jpipe, I'm sure there will be a difference in performance. Also, my Jpipe was custom so although it was a semi-pain to get on, it was easier than cutting an aftermarket Jpipe and having it welded in place of their collector.

Fatfrii

sonnick can u please post pics? and i really dont see how jpipe (in this sense having equal length primaries)is really all that important. i feel that it would be more beneficial eliminating those to increase power, from a basic physics ponit of view. an example of some one here is swooshes exhaust. although its a true dual. but i dont know if he has dynoed before and after.

where i am stumped is how long i let those primaries run before the merge and the venturi collector

Sotiris

what an awesome idea nice work sonnick

Sonnick

I will post pics when I get a chance. I do have pics on v.6.p in the 7G performance section under my dyno thread, but I will post here as well. I thought I had updated the exhaust guru thread with pics but I was wrong!

Fatfrii

add the link to the guru thread as well please

Sonnick

Sorry for taking so long. Here is the link to the guru thread below.

https://acurazine.com/forums/3g-tl-performance-parts-modifications-112/exhaust-gurus-get-here-800844/

In this pic my collector is on the right.


That's one of it installed.


I need a better camera. These are iPhone pics.

Fatfrii

iphone pics r just fine for this! but id still invest in a DSLR and nice lens for the prettier pics. im gonna get into the thread now thanx

wait turns out i have already read that thread in fact i posted in it too hahaha. can u post pics of a custom jpipe? BTW i like urdesign but i think it would be better if the openings were the same diameter on the venturi y pipe. I dont know where to find one of those hour glass looking ones for sale but i have seen them.

Fatfrii

wow looking back at what posted back then....i sure sound like a dumbass^

i miss having money to put into my TL