[Mk2] [Turbo] Do i need an aftermarket intake manifold?

[sky-net]

Hi folks,

I've read a few times that stock manifold (rev1) tends to lean cylinders 2/3

I'll be looking for a power level from 300 to 350 hp. Despite the fact i don't have have defined turbo and/or cams yet, my engine will be managed with a pcf + datalogit combo... So giving these cylinders a bit of more juice could be an option.

i'd like to ask you if you think an intake center manifold from RacerX should worth the money, as they have a 20% discount until tomorrow... And they might correct the stock intake flaws.

Would you buy it?

Cheers!

[MikeyB571]

I'm running something near those figures on a rev2 engine with forged bottom end and a hybrid CT20 turbo with the standard manifold.
I am putting a little extra fuel into cyl 2 and 3 as they were prone to early det, so they were leaning out.

But I am eventually going to get a better inlet manifold and charge cooler, plan to do a custom job with Bobs help at Concept Racing.

But if X racer are doing a discount then I might have to consider that

[sky-net]

Is your TVIS functional?
If they sell me a phenolic spacer and can powdercoat their intake for legal reasons, i'll be in!:thumleft:
(spending more money )

[MikeyB571]

I like shinny bits

Yes flaps are still functional, I get a power dip if I don't use them. I'm not sure what the effect is when you upgrade the manifold, I expect the air flow is so different that you are better of ditching the flaps.
And I do like removing stuff

[sky-net]

Yep, air flow will be different

I've read that rev2 (8 intake runners) are bigger than rev3 (4 runners)... So TVIS improves flow at low rpm threshold shutting some flaps. This improves power response at low revs. After 4000 rpm or so... all flaps are opened.

It's said that rev3 intake is better designed... So TVIS was no longer needed: Air flow is supposed to be better across these optimized runners.

I'm not sure if a punchy ceramic ct26 would deliver power a bit slower in a rev3 intake.

[androo007]

I was advised to tell my mapper to add between 1 and 1.2% extra fuel to injectors 2 and 3 to accommodate. It's the centre fed throttle body that gives tenancy to lean out

[sky-net]

Thanks Androo007,

Their centre feed intake manifold seems to have these advantages (amongst others):
- Moves throttle body forward to reduce cylinder 2/3 lean condition
- Angled plenum after entrance of throttle body improves flow to all cylinders

I think I'll order one tonight. 20% discount is a good deal.

Regards

[Mike N]

I made 380 on a rev 1 engine with rev 1 T/B and inlet manifold, less TVIS flaps.

Had different cams forged piston stand alone and turbo though.

The truth is for the price of that magic inlet manifold you could probably convert the head to Rev 3 set up and gain 30bhp without trying.

Thats basically what I did.