john banks

Just wondering - heard that the extra lag is a result of the larger pipe volume, but there is better flow at higher revs. As a result at system level (ie including the exhaust manifold and uppipe as part of the exhaust housing setup) could you consider that A has effectively increased all other things being equal? It feels like you have stuck a bigger turbo on when you drive it.

Andy.F

Not sure John but it just shows what the scoobs give away to the EVO. With very short big bore headers (evo) you would have the big turbo feel without the extra lag.

Pavlo

But the evo gives away weight distribution, C of G etc, so it's not all bad.

I saw the Midland Impreza 'balanced manifold' at the Donnington show, for the money I can't say I was that impressed. Boiled down to 2into1 right by each cyl head, loop from head to head, then a pipe from the middle of the loop, that went up to the turbo.

Probably quite a low (physical) volume system, so might be good for lag. The haven't dynoed it yet, yet they seem impressed with low down torque, but they would say that! (Graham from MI is a very nice chap btw).

Someone has to come up with a cheaper solution than the PE/JUN manifold, which does look very nice.

Paul

Erik

You are talking about manifold, so may I ask something sirs?
I want to make ported OE exhaust manifold. This is very cheap way how to increase HP and Nm a little bit too. Just at same time thinking about www.thermotec.com products. Beter heat inslulated manifold could deliver more energy to turbo nad lag could be smaller to.
Am I right?

john banks

I wrapped mine and it makes your car smoke at the lights for a few days! And the smell is offensive.

dowser

Erik,

Porting the OE headers has a noticeable effect on performance

John - what is A, what is R?! Certainly the gases flow slower at low revs but are not so restricted at high revs with a replacement manifold. We've recently tried a locally produced design (pictures posted previously) - boost threshold moves up 200rpm (without a remap). On a recent dyno session two similar 99/00 vf23 cars running 1.2bar had a difference of up to 20PS and 20NM peak figures, all of it above 4.5k from memory. One had the new headers

Richard

john banks

A/R is a measure of the reduction that occurs through the exhaust housing and hence is one factor that influences the compromise of a turbo between bottom and top end flow. In enlarging the effective manifold CSA this means the gases are slowed but as you say flow should increase higher up. So a gas flow coming from a larger CSA to the same CSA for the "nozzle" driving the turbine could effectively "resize" your exhaust housing and make you do impressions of a bigger turbo? Certainly this is what seems to happen with Stephen Done's and my car with two different types of manifold. However, I still think the big turbo is a better compromise if you were to do one or the other.

dowser

Hhhmm - don't know. Given that the final interface between the manifold/up-pipe and turbo is the same size regardless of whether you're talking OE/OE or big/big, maybe big manifold & OE turbo is best for accelerating the gases into the turbine wheel? But wouldn't this just give better spool up?

I think the best solution is to do the manifold and turbo, you just lose some of the quick spool up (just how much can be given back with remapping - have you done yours yet?), but once in 'steady-state' operation it pulls like a train through to the red line.

Fitting my manifold tomorrow

Richard

john banks

I'm doing it this pm. I have the boost coming in later even with maxxed out duty cycles but that is to be expected. It needs more fuel during spool up as the lambda is reading zero.

Erik

John

can you tell me how much 2" x 1/16" x 50' wraps I need for OE manifold?

Thanks

Erik

john banks

It was about £60 from Scoobysport. Give them a call.