Pete Croney

John you haven't upset me, for certain.

FWIW I was using a VF24 on my RA, Phil uses a VF28 but I'm not sure what Anders and Nicky use.

These are 3 weeks from order, to make and cost £910+vat.

Picture, as requested...

StephenDone

Hi John,

Since you have the easy to fit style of manifold (relatively), could you fit the manifold to get a before and after. Then fit the turbo and get another. You'd have 3 graphs then to compare. Ideal world and all that.

btw, on a recent car we mapped that had a new VF22, the results kept getting better and better for the first few hours of use - like the turbo was loosening up a little. Everytime we did a run, the spool up moved about 50RPM left, so give a while before you try to map the boost control accurately.

Cheers

Steve



[Edited by StephenDone - 6/18/2002 2:20:22 PM]

Neal Gibbons

Pete’s right, I was disappointed to see the manifolds taken off, I’ll be even more p****d off if they work for John

It was Stephen’s gains with his manifold that spurred me on to get them but in hindsight it was naïve of me to think I could just bolt these things on and all would be OK. I always had it in the back of my mind that I would need a larger turbo and a full re-map but today the additional cost is just not going to fly with the financial controller (!) So I was hoping that the TEK2 would work but, alas, despite the efforts of Stephen and Merv something else is needed. Like Floyd it seems I have a slow MY00 Anyhow, I have John’s BB and center section to look forward to, at least my car will sound nice!

Neal

Adam M

double post oops.

[Edited by Adam M - 6/18/2002 3:20:01 PM]

Adam M

Richard,

equal-length can be defined 3 different ways,

(a) is equal physical length (ie. to the eye)

(b) is equal travelled distance by the gases

(c) is equal length from port

I think tuned length normally refers to (b)

On another I dont understand why everyone is fussing here.

the only important points here are the resistance of the pipework to the the gas stream, and the proximity of the turbo to the exhaust ports. the closer the better for reasons stated above.

in normal aspirated cars, the point on the equal length headers, is for the resonance to occur at the same rpm point, this means that at that specific rpm, you get massive amplification of the pressure wave created by the exhaust, the benefit of this being the exhaust is sucked out of the cylinder. at the same point, this will leave the pressure in the combustion space slightly lower than it would other wise have been. meaning the exhaust gas has been completely removed from the next charge. This means more air can be burned next time round, it is effectively like a mini turbo charger, in that at that point you can ram in more air than you otherwise could because it doesnt have to push ex gas out the way.

this of course depends on the cam profile as in na cars there is an overlap between inlet and exhaust valve opening, but this is not always the case with forced induction.

With internal wastegate turbo charged cars, this (pulse) extraction is never going to be important because whatever happens the gas stream has to travel through the impeller wheel of the turbo. An external wastegate car on boost can yield some advantage, except that off boost the car is operating under vacuum anyway so efficient extraction is much less important.

The only important point to consider is the diameter of the up pipe which dictates the gas speed entering the turbo.

I think people place too much importance on the length of the primaries, thinking that the boxer sound comes from the unequal nature, but it doesnt. Most of the comes from the resonance characteristics of the cast standard headers combined with the wrong pairing of cylinders on a four cylinder flat plane crank engine.

Nearly all the tubular headers I know of lose the boxer sound (mrts dont much) but also leave the car quieter, especially at idle, and in particular anders. if only they didnt blow apart all the time!

JamesS

Fitted HKS headers a couple of weeks after porting the std headers. Running VF30, SS up-pipe etc.

Lost on boost-threshold slightly but when it spooled, blimey - definatley more torque and more power......

And this was pre-remap.....

JamesS

..just to add that porting the std headers lowered the boost-threshold. So the HKS from the standard ones are probably similar in terms of boost responce.....

Also the exhaust flange on the HKS headers is the same as the std headers ie a nice fat 4mm face for the exhaust gas to hit. Flowed them as I did on the OEM ones.....

john banks

The car I mapped today actually had HKS headers. However, the contribution of the manifold to overall performance was considerable. Using high wastegate duty cycles the turbo did come in a few hundred RPM later and did not reach the same boost. I had to add considerable amounts of fuel everywhere, even compared with an AE801 map to get the lambda voltages up to about 880mV. However, the airflow for a TD04L was nothing short of sensational like Stephen's car - at only 16 PSI it was the same as a hybrid TD04L at 18 PSI, and it allowed about 2 degrees more advance. The noise was very pleasant and quite quiet. Very impressive stuff.

john banks

Looking at the pictures the Scoobysport one and PE one look similar in layout and pipe diameter. The HKS one looks anything but equal length to my eyes from Christian's picture. Whatever, it is very effective. Have high hopes for the SS one too from the pictures.

carlos_hiraoka

What is the design of the following extractors (4-2-1 / 4-1):

a) HKS

b) PE

..... it is thought that 4-1 give better top end while 4-2-1 give better midrange.

Carlos H.

submannz

Adam is exactly right with what he has said, a tuned length extractor does take it account the equal distance travelled by the gases.

[Edited by submannz - 6/18/2002 10:45:25 PM]

ChristianR

iTrader: (1)

nom

Umm, that very nice, Christian, but what's it there for

submannz

A true tuned length extractor, is actually tuned on YOUR car, therefore getting the maximum benifit, the reason this is such a benifit is all cars are different when they come out from the factory due to manufacturer tollerances on every single part.

This is hard to explain but I will try my best.

They make up the basic equal length extractor, drill little holes into the exhaust so they can inspect where the flame pulse is, when the flame pulse hits a low they cut the pipe and weld the next part. the reason they use the low part of the pulse so the slight weld intrusion into the extractor has a lot less flow restriction.

The most amazing extract I have ever seen actually was larger and smaller to the same pattern of the flame pulse, which gave a further 2% gain, something to do with increasing the torque.