Inlet manifold for ITBs on 944 S2

[Mac944]

Hi,

I'm upgrading the S2 engine in my race car and one of the mods I'm hoping to do over the winter is to add individual throttle bodies and run an aftermarket ECU (which is permitted within the series).

The throttle bodies themselves can be sourced easily enough but I'm struggling to find a Weber DCOE manifold to fit a 944 S2.

I've tried Jenvey and a couple of other places who I was hoping might be able to help but no joy.

One firm has said they can produce a completely bespoke manifold for my specific application but an expensive exercise.

Any ideas if one already exists/where I might get one/if anyone may be able to modify the existing manifold to accept ITBs?

Many thanks in advance!

 

[colin944]

This is something I want to do to my own S2. I couldn't find a suitable inlet manifold and thought the only way to do it would be to modify the standard inlet by cutting it and welding a plate to it and attaching the ITB's to that.
Any good alloy welder or engineering shop would be able to do it for you.

 

[Mac944]

That is probably the way I'll have to go for now although I have been informed by an engineer who manufactures ITB that because cylinder head entry is oval and the ITB is round there is already an issue with airflow. For the best performance the airflow needs to optimised by making the passage as smooth as straight as possible to reduce drag, this normally means a round to round.

The modified manifold will require polishing back any imperfections, casting marks, welds etc on the inside but even then it won't be perfect but it'll work to an extent.

 

[944 man]

Im going to predict a disappointing outcome, unless you can change the camshafts too.

 

[Mac944]

Why is that?

Throttle bodies were recommended by a number of people including EMC in Brum who build most racing Porsches in the UK.

I've also spoken with other race engine builders and the main concern was tuning but as I'm changing the DME for a modern and fully customisable ECU, tuning shouldn't be a problem.

 

[944 man]

Because the original cams are so steady. Ask Kevin if theyll be far better with optimised camshafts... []

 

[944 man]

I was about to suggest an Augment Automotive ECU too, but Tom hasnt made an S/S2 compatible version yet. Id still ask though, as it might be possible to use an 8V DME and even if it needs work, itll be far easier than an Emerald or MS (*shudder*) etc.

 

[Mac944]

Umm that's interesting, I think I spoke with Alex but at the time I'd mentioned reprofiling the cams and that was shot down pretty quickly.

I'll check again with them but do you recommend any particular performance cams?

 

[Mac944]

I've spoken to Tom in the past about his ECU and that is one of the contenders along with others (although the ones you've mentioned are not them).

I'm aware the power gains with ITBs will be minimal on the S2 but responsiveness will be better (providing I can get a reasonable setup).

 

[edh]

I thought the biggest issue was runner lengths - with the brake servo and master getting in the way. I have seen pictures of oddly curved runners that one firm made. I'm sure we had this discussion last year & the consensus was that you'd move the power band up and therefore really need an engine happy to rev much higher, so incur a whole lot of extra costs. Cat cams do camshafts (and solid lifters I guess), don't know what work you'd need on the bottom end. 968 heads have bigger valves (inlet or exhaust? can't remember which) so might be worth investigating.

What are you racing in? seems pretty free of restrictions on engine mods

There is a 400hp n/a 3.0 16V ITB motor on Rennlist - in Singapore I believe. That thing is just amazing. Revs to 8k IIRC

Bogg Bros would be my first port of call for any inlet manifold stuff

 

[Indi9xx]

Talk to Colin at 9m, I know a few years ago he made up some manifolds to test throttle bodies on a 968 but I do not think he ever finished the entire project, so he might still have the manifolds he made and would be able to tell you what throttle bodies they were designed to marry up to.

Cams in any car really need matching to the dynamic of the intake among other things, and the S2 and 968 cams are extremely conservative even for the standard intake arrangement. In fact, all 944 cams are seriously mild.

 

[Mac944]

ORIGINAL: edh

What are you racing in? seems pretty free of restrictions on engine mods.

I'm sure we had this discussion last year & the consensus was that you'd move the power band up and therefore really need an engine happy to rev much higher, so incur a whole lot of extra costs.

I'm racing in Future Classics, throttle bodies are permitted but I could run in to trouble changing the cams as I must use the original engine, although it doesn't specify that internal mods shouldn't be done, so reprofiling the original cams might be OK if that can even be done?

The engine is having a complete rebuild although internals will be standard.

 

[944 man]

Piper can do that (I think it was Piper), and use a Lotus profile. Andy97 will be able to tell you when he sees this (re eligigability, not who can regrind cams).

 

[Mac944]

What will the Lotus profile give me?

 

[edh]

ORIGINAL: Mac944

ORIGINAL: edh

What are you racing in? seems pretty free of restrictions on engine mods.

I'm sure we had this discussion last year & the consensus was that you'd move the power band up and therefore really need an engine happy to rev much higher, so incur a whole lot of extra costs.

I'm racing in Future Classics, throttle bodies are permitted but I could run in to trouble changing the cams as I must use the original engine, although it doesn't specify that internal mods shouldn't be done, so reprofiling the original cams might be OK if that can even be done?

The engine is having a complete rebuild although internals will be standard.

So are you entering the car as a 944S2 now?

 

[edh]

hmmm

9m

 

[J.C944TurboMan]

Long shot mate , would a 968 manifold make do ?

http://www.tracmac.com.au/products_porsche.html

http://www.haywardperformance.com/intake_systems.php

Google race inlet 944 S2 manifold and you will be surprised what you can find !

Is that what you are looking for ?

 

[Mac944]

[/quote]

So are you entering the car as a 944S2 now?

[/quote]

I will be yes. The body shell is an S2 anyway but with 2.7 running gear and front bumpers so I'm just updating the running gear and silhouette to S2 spec plus permitted mods.

 

[Mac944]

ORIGINAL: edh

hmmm

9m

Very nice, that's the sort of thing I'm hoping for!

 

[Mac944]

ORIGINAL: J.C944TurboMan

Long shot mate , would a 968 manifold make do ?

http://www.tracmac.com.au/products_porsche.html

http://www.haywardperformance.com/intake_systems.php

Google race inlet 944 S2 manifold and you will be surprised what you can find !

Is that what you are looking for ?

I've searched google and have found lots of images but trying to nail down some of people that produce these was proving difficult.

The links are very useful. Thank you!

It's worth mentioning I 'must retain the original induction type', I need to check with the club but that may be open to interpretation in terms of custom manifolds. Although correct me if I'm wrong but I believe The 968 manifold is sufficiently different that I couldn't easily swap to it.