Offroad-Express

Looking for feedback on what size exhaust I should fit on my surf(twin tdo4 turbos,),?
At this stage thinking 2.5dump through to behind transmission to where I could merge into single 3inch? Dont really fancy doing it twice! Will require some 90º to get over rear diff...
Cheers Alistair

On my 1UZ na surf I had twin 2.25 off the manifolds into a single 3in. Was quite boomy but flowed well.

On my 1UZ Soarer I ran dual 2.25 pipes with an X pipe at the front with twin magna flows. Sounded and looked and went well.

Surf was a compromise but a lot of stuff on a conversion is never perfect.

Go as big as you can at the collectors.

Matt

I think I could probably squeeze twin 3inch in, all the way through, but concerned itd be too big?or even too 2.5?

Don't go too big.. as it'll have a negative effect.. I went 2.25 from memory collected very early from the headers.. then now I am 3" as forced induction required me to do it that way.. as the 2.5"was too small .
The benefit of going 3" now is it's keeping my engine a lot cooler as the gas's are getting out faster.. research is your friend for getting it right.. as I have spent a lot of time and energy ( making a system)ended up just wasting my time..

Twin 2.5 would work well twin 3 might be a bit much.
2.5 pipe is also so much easier to fit 3 inch pipe needs a lot more room for bends to go over the diff.

with turbo's, as big as you can fit in there.

I have heard that with forced induction on a lexus 2.5 can still be limiting. Mine will be 2 of 2.5 into single 3. Couldn't fit anything bigger.

Why not twin 2.5 or 3inch and put stacks up behind the cab. Not diff clearance issues then

Just had a look at your thread and realised your building a surf not a hilux, Maybe lake pipes then?

ChurchurDan wrote:Why not twin 2.5 or 3inch and put stacks up behind the cab. Not diff clearance issues then

cause thats a bit too redneck for even me.....
cheers guys im thinking twin 2.5 will be the go.

i had plenty of room for twin 2.5 system in surf

ChurchurDan wrote::oops: lake pipes then?

Hell yea.. red neck styles

I have twin 2.5" on mine with a crossover pipe, when it was on the dyon last time it was pointed out that it was choking at the top end. If i had the room id be going to 3"

tweake wrote:with turbo's, as big as you can fit in there.

What this guy says. Turbo's like zero backpressure.

Madaz wrote:I have twin 2.5" on mine with a crossover pipe, when it was on the dyon last time it was pointed out that it was choking at the top end. If i had the room id be going to 3"

ah I see.real world exp, guess that answers my question then!

cheers

3 inch? off four cylinders ...think about that for a second.

you know all those honda civic's and riced up hatchbacks you see with 3 inch exhaust's.....

I can under stand 3 inch on a single turbo six cylinder but three inches off either side of a 4 litre v8 which is effectively 2 litres per turbo charger.
There ain't enough gas flow to warrant it.

Even a GTR skyline doesn't need 3 inch exhaust's to make the axle snapping power expected from a twin turbo.

skidmark wrote:

ChurchurDan wrote:Why not twin 2.5 or 3inch and put stacks up behind the cab. Not diff clearance issues then

cause thats a bit too redneck for even me.....
cheers guys im thinking twin 2.5 will be the go.

What's wrong with rednek styles? 2 million americans cant be wrong...

Madaz wrote:I have twin 2.5" on mine with a crossover pipe, when it was on the dyon last time it was pointed out that it was choking at the top end. If i had the room id be going to 3"

Crash bandicoot wrote:3 inch? off four cylinders ...think about that for a second.

I can under stand 3 inch on a single turbo six cylinder but three inches off either side of a 4 litre v8 which is effectively 2 litres per turbo charger.
There ain't enough gas flow to warrant it.

Even a GTR skyline doesn't need 3 inch exhaust's to make the axle snapping power expected from a twin turbo.

I would tend to agree with you Crash, but the dyno man says you are wrong. Maybe there are other things coming into play on the GTR?

shortylux wrote:

Madaz wrote:I have twin 2.5" on mine with a crossover pipe, when it was on the dyon last time it was pointed out that it was choking at the top end. If i had the room id be going to 3"

Crash bandicoot wrote:3 inch? off four cylinders ...think about that for a second.

I can under stand 3 inch on a single turbo six cylinder but three inches off either side of a 4 litre v8 which is effectively 2 litres per turbo charger.
There ain't enough gas flow to warrant it.

Even a GTR skyline doesn't need 3 inch exhaust's to make the axle snapping power expected from a twin turbo.

I would tend to agree with you Crash, but the dyno man says you are wrong. Maybe there are other things coming into play on the GTR?

True, the only factors I could see coming into play would be crank shaft mass and manifold design, but that would only really alter the torque curve.

We just changed from twin 2.5s to twin 3s. With no other changes the result was a descent increase in mid range torque.

Crash bandicoot wrote:3 inch? off four cylinders ...think about that for a second.

you know all those honda civic's and riced up hatchbacks you see with 3 inch exhaust's.....

I can under stand 3 inch on a single turbo six cylinder but three inches off either side of a 4 litre v8 which is effectively 2 litres per turbo charger.
There ain't enough gas flow to warrant it.

Even a GTR skyline doesn't need 3 inch exhaust's to make the axle snapping power expected from a twin turbo.

Show me a worked GTR thats running a 2.5" exhaust???

Madaz wrote:

Crash bandicoot wrote:3 inch? off four cylinders ...think about that for a second.

you know all those honda civic's and riced up hatchbacks you see with 3 inch exhaust's.....

I can under stand 3 inch on a single turbo six cylinder but three inches off either side of a 4 litre v8 which is effectively 2 litres per turbo charger.
There ain't enough gas flow to warrant it.

Even a GTR skyline doesn't need 3 inch exhaust's to make the axle snapping power expected from a twin turbo.

Show me a worked GTR thats running a 2.5" exhaust???

I spied a worked GTR last week, straight 4 inch exhaust.

I changed to a 3 inch system and also noticed a different.

yea plenty of 2l subarus/evos with 3inch exhausts..so makes sense.Anyway Ive heard enough to go 3inch.chur

Madaz wrote:

Crash bandicoot wrote:3 inch? off four cylinders ...think about that for a second.

you know all those honda civic's and riced up hatchbacks you see with 3 inch exhaust's.....

I can under stand 3 inch on a single turbo six cylinder but three inches off either side of a 4 litre v8 which is effectively 2 litres per turbo charger.
There ain't enough gas flow to warrant it.

Even a GTR skyline doesn't need 3 inch exhaust's to make the axle snapping power expected from a twin turbo.

Show me a worked GTR thats running a 2.5" exhaust???

exactly the point... you dont need to work a RB26dett to get good power. mine is 320 bhp @6800rpm at the wheels with the factory setup. just tickled the fuel pressure timing and boost. I am happy with that, it's enough to destroy axles and diffs which it has done in the past.

working/ turbo charging a motor like that for the purpose of revving the shit out of it in a mud hole...is well stupid.

You are just asking to melt pistons trying to keep a big engine like that on the powerband when you need artistic driving skills and feathering the throttle to maneuver through tight spots..the poor computers going to be going too much fuel/not enough fuel/too much fuel/ not enough fuel...engine's like these were made as tarmac specials. your better of throwing your money at a big diesel. It'll last longer.

you want proof ask the owners of the big money trucks that had to limp out of the army grounds last year. too much money not enough sense.

Crash bandicoot wrote:

Madaz wrote:

Crash bandicoot wrote:Even a GTR skyline doesn't need 3 inch exhaust's to make the axle snapping power expected from a twin turbo.

Show me a worked GTR thats running a 2.5" exhaust???

exactly the point... you dont need to work a RB26dett to get good power. mine is 320 bhp @6800rpm at the wheels with the factory setup. just tickled the fuel pressure timing and boost. I am happy with that, it's enough to destroy axles and diffs which it has done in the past.

working/ turbo charging a motor like that for the purpose of revving the shit out of it in a mud hole...is well stupid.

You are just asking to melt pistons trying to keep a big engine like that on the powerband when you need artistic driving skills and feathering the throttle to maneuver through tight spots..the poor computers going to be going too much fuel/not enough fuel/too much fuel/ not enough fuel...engine's like these were made as tarmac specials. your better of throwing your money at a big diesel. It'll last longer.

you want proof ask the owners of the big money trucks that had to limp out of the army grounds last year. too much money not enough sense.

I'm not sure what you are getting at here Crash. I think everyone who has commented with you would agree that a thoroughly worked high strung motor is not the best thing for an off roader.

What we are discussing is weather or not a 2.25 , 2.5 or 3 inch etc exhaust would be good for Skidmarks twin turbo lexus. The consensus from people with firsthand experience seems to be that there is a tangible advantage in going for at least 3 inch.

In the scheme of things, a force feed lexus is not necessarily an expensive high strung motor. Plenty of them in offroad trucks working reliably. So I think Skidmark is on the right track.

Not having a go at you Crash and I hope it doesn't sound that way. Just saying I think we got off track. I can see form other threads that you have experience and seem to be pretty clued up on the tuning/performance side of things.

Better off with a diesel??? Wtf???
Thougth this was a thread about the best sized exhaust in a forced inductioned 1uz???

all depends really on how big these turbos are

cornflake wrote:all depends really on how big these turbos are

only td04's ie standard wrx ones.but 3inch bends have been brought so there going in!

skidmark wrote:

cornflake wrote:all depends really on how big these turbos are

only td04's ie standard wrx ones.but 3inch bends have been brought so there going in!

yip should be good for power and stuff