Problems With Exhaust Size

odelarosa

New Member
Hello, i'am new here and i'am a no native english speaker xD, i have a Toyota Altezza with a 1UZ VVT-I Engine and W58 manual transmission, my friends say me that my exhaust is very small, from Headers to Y pipe is 2.50 but half way, before reaching the Y pipe is 2.0, from Y pipe to rear bumper is 3.0 (this is not done yet, this is in process).

My car for now is for daily and some drift day in my country, so, i want the (almost impossible) balance between a good sound and not loose HP/Torque.

PD: i want more or less 300+HP

Please, Teach Me.
 
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016UCH

New Member
Hey man,

I'm not an expert but I've read lots of posts that say the smaller the pipe the better for low end torque/power. In fact most people swear that the stock 1uz Y-pipe is hard to beat. Ideally, since your engine is stock, you're better off with the stock Y-pipe set-up.

Look around for posts by JBrady. I think he's the subject matter expert.

Good luck .
 

gloverman

Well-Known Member
On 1uz and 3uz use headers where i can then from headers to merge (y pipe if i can) use twin 2 1/4. From join single 2 1/2. One big packed muffler. There will either be a resonator or converter in the system too. Ive done 3 inch but they make more noise and less torque. If im doing an LS1 which is 5.7 litres then i go up to 3 inch.
 

Zuffen

Super Moderator
Staff member
Tell me about 3"and torque loss.

I have twin 3"left over from my Supercharged engine and I'm too lazy and mean (the system cost $5,000.00 over ten years ago) and whilst its not to noisy it does rob the torque.

Too big a pipe is the commonest error most people make.
 

gloverman

Well-Known Member
It was really interesting comparing setups when I had a dyno. Max power was always the similar between systems. One memorable comparison was two utes both built to the same spec, same gearboxes, both early series 1 engines, same flywheel and clutch, same diffs, same exhaust manifolds and same ecu with exactly the same tune loaded. Difference was one customer listened to me a had 2 1/2 system other thought exhausts theory was bigger the better like cocks and wanted it noisey so insisted on a 3 inch system. Test drive on a corner close to workshop 2 1/2 barked tyres on hard acceleration upon exit, 3inch didnt. And I tried it a few times. Ok quite a few times haha. Even after the tune was personalized the result was the same.

Did the builder of your twin 3 inch system expect you to make around 750ish HP?
 

Zuffen

Super Moderator
Staff member
We were chasing better than 750.

The engine was probably the most complete twin screw Supercharged attempt at huge power and it gave around 600 at the end but was undriveable due to wheelspin and fuel economy.

I'm over fighting with it and couldn't be bothered replacing the whole system.

If i did it would have an LS3 hanging off the front of it.
 
Tell me about 3"and torque loss.

I have twin 3"left over from my Supercharged engine and I'm too lazy and mean (the system cost $5,000.00 over ten years ago) and whilst its not to noisy it does rob the torque.

Too big a pipe is the commonest error most people make.
I take it that this means that you lose the pump/suction effect in the pipes if they are too large.

I have 4 pipes (2 cylinders/pipe) start with a small piece of 2 inch then 2.5 inch then finally 3 inch.

Do you have to maintain the "smaller size" all the way to the end in order not to loose power,
or would it suffice to have 2 inch/2.5 inch for "most" of the distance?

(my interest, now, is more for lower end torque than top end hp)
 

Zuffen

Super Moderator
Staff member
The further the gases get from the exhaust valve the cooler they get so the pipe can theoretically get smaller as the gas compresses as it cools.

If running 4 pipes I would think anything over 2"would be way overkill.

John Cribb will have good advice so wait on his reply.
 
The further the gases get from the exhaust valve the cooler they get so the pipe can theoretically get smaller as the gas compresses as it cools.

If running 4 pipes I would think anything over 2"would be way overkill.

John Cribb will have good advice so wait on his reply.
thats a personality defect of mine, opting for overkill solutions


yep,
eagerly awaiting Mr Cribb
 
There's a bit of Tim Allen (Tim the Toolman) in all of us who modify cars!
hehe, or engine/boats

a related question, with my 4 pipes, 2 pipes each side/bank
I paired the following cylinders into 1 pipe

the cylinder that fires first + the penultimate firing cylinder
and
the cylinder that fires as number 2 + the cylinder that fires last

does that sound about right?
 

cribbj

"Supra" Moderator
Staff member
Rod, thanks for the kind words, but sorry guys, I'm no exhaust expert. Kelvin (Gloverman) knows what works best for which application, and I would follow his lead and recommendations.
 

016UCH

New Member
Could someone please tell me an acceptable length for secondary pipes in a 4-2-1 system for the 1UZ?

I got tired of my stock manifolds and hacked them up to make a home-made header.

I just don't know how long I should make the secondary pipes. ...

Here is a pic of the hack job.

Screenshot_20181229-213426.jpg [I know the welds are crap, I'll finish them off with a Mig to look better once I'm done ]
 
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016UCH

New Member
Also, would it do any harm to move the primary O2 sensors further down from the stock position? I'm asking coz I intend to re-use the stock collector where the o2 bung is.

Thanks
 

gloverman

Well-Known Member
Length is going to depend on the tune of the engine. Last set i designed was for a quite modified engine and the secondaries ended behind the drivers seats. If you want enhanced torque make them long. Also is going to depend on the chassis its in and the room you have.
 
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