ITBs on the 16v engine

[Tam Lin]

I'm not sure if it is because of the 944-owning demographic (mostly in the USA), but it strikes me as strange that all the "tuning" parts seem to be available for the 928S4 & on, rather than the 944s/s2/968. E.g. this site http://www.928sg.com/modifications.htm

1) Has anybody heard of/seen/have a 16V M44 motor with ITBs?
2) Matched exhaust manifolds?

 

[944 man]

I dont think that Ive seen any 944 running with throttle bodies. Theyll certainly need to replace the DME too, but how would you measure airflow? Id be looking at a plenum chamber and a manifold absolute pressure sensor (youd need a sealed tract for a MAF too, but thatd cost more and work less) system; but itd be a long road and youd be on your own. That suits some people, but Id like to think that there was someone to refer to if I got stuck.....

Simon

 

[zcacogp]

'Tis a good question, and one that I was pondering the other day. S2's are generally regarded as 'untunable' (bar chips and other such trivialia), whereas there is a whole industry around tuning the Turbos. This is not the case in the rest of the automotive world, where there is a wealth of gubbins to make a N/A car go faster, and the link you posted is a great example of this.

There must be scope for a few (if not a lot) more oomph to come from the (S and) S2 engine. I know little about this area (944 man on here seems to know a lot more), but I'd guess that throttle bodies and fully mappable ignition and fuelling would be the place to start in terms of hardware. You'd then need to develop the software to run it all.

I have no grasp of what sort of gains may be available, but suspect that the improvement would be more in terms of torque and drivability rather than outright power.


Clearly, cost will come into it. ITB's and fully mappable ignition/injection will never be cheap, and I suspect that the old mantra of "Buy an S2 if you want to drive a standard car, buy a turbo if you want to modify" will always hold true.

I guess that explains the lack of development; the presence of the turbo in the 944 line-up. Forced induction cars are always easier to tune, and will yield more improvement for much less money, and hence I suspect that those who have wanted to tune have gravitated to the turbo models, and the tuning companies have accomodated (or vice versa). Pushing this a little further; had the 944 turbo not been sold, maybe there would be more tuning gubbins available for the S2.



Oli.

 

[Peter Empson]

I know 9M developed a prototype for their 968 but I can only imagine the gains weren't beneficial/cost effective as it never was marketed. An American firm also produced some, I believe they sold a handful to racers, it's worth a search on Rennlist for that one.

 

[333pg333]

This is from a highly modified 924 turbo out of the UK. It's a bunch of custom work but the fact that it's forced induction shouldn't make any difference. The guy uses this primarily for Hillclimbs. Can't think of his name. Do you know this car Peter? The owner is a very nice guy and he discussed the car in greater detail on a Rennlist thread. I'll see if I can find it. I want to copy the style of flow through ducting he's got for the i/c and radiator.

 

[333pg333]

One more pic....

 

[PJS917]

9 M tried throttle bodies on the 968 but went down the supercharging route as they could not get the TB to work properly. The 968 head is capable of producing far more power but was not developed as it should be as it would have been a quicker car than the 993 which was for sale at the same time. I had my 968 head polished and ported and then re-mapped and got an extra 12 hp over the standard and a useful increase in torque.

I intend to do the same polish and porting to my S2 but with other lightening mods to the lower end. This will have to wait until finances allow but I am sure with a little work it will give a power output far more similar to a standard 968.

 

[TheFiend]

Not all cars are well catered for by tuners.

My previous car, a Ford SportKA, was an example. Induction kits/panel filers are available but that is about the limit of tuning hardware available.Only Miltek produced an exhaust system suitable fot it, and none of the "chip" tuners were interested in doing anything for it. If you wanted more horsepower you basically had to go for the option of an RS Turbo or 2 litre Zetec engine transplant. A bit more stuff was available for the 1300 engined Ka. I found the SportKA was a great car in standard form, so was quite happy with just replacing the panel filter with a K & N one.

 

[edh]

ORIGINAL: 333pg333

This is from a highly modified 924 turbo out of the UK. It's a bunch of custom work but the fact that it's forced induction shouldn't make any difference. The guy uses this primarily for Hillclimbs. Can't think of his name. Do you know this car Peter? The owner is a very nice guy and he discussed the car in greater detail on a Rennlist thread. I'll see if I can find it. I want to copy the style of flow through ducting he's got for the i/c and radiator.

It's Steve Bassington's sprint car - posts as bassgt on most forums. It's a fantastic machine, & he's currently re-shelling into an early non- sunroof 924 I believe. Lots of posts on 924.org about this car. Can't remember what ECU he uses, I think it's Motec.

 

[Tam Lin]

ORIGINAL: PJS917

9 M tried throttle bodies on the 968 but went down the supercharging route as they could not get the TB to work properly.. I had my 968 head polished and ported and then re-mapped and got an extra 12 hp over the standard and a useful increase in torque.

I intend to do the same polish and porting to my S2 but with other lightening mods to the lower end. This will have to wait until finances allow but I am sure with a little work it will give a power output far more similar to a standard 968.

Didn't the bloke who worked on porting your head comment on the relative restrictiveness of inlet/exhaust manifolding on the 968 (I may be mixing up my 911&Porsche World articles, in which case, apologies)?

@944 man I was thinking of TPS mapped fuelling for the ITBs (I'm an ex TVR Cerbera owner). This worked surprisingly well, considering the, um, simple engineering, at everything other than passing emission tests. And for those there is always isopropyl alcohol.

I just don't get why a relatively nice hemi 16v head, safe to 7000 rpm, is producing around 57 BHP per litre.

 

[PJS917]

I did actually start to write about the restrictivness of the inlet manifold (in the post above) and how unfinished the design is. The head and inlet manifold could be significantly improved and I did find a company that was keen to do the work. They have sadly diversified. I have also stopped developing the 968 as I bought my S2 track day toy. If Porsche had developed the 968 head/manifold as they should have it would have been a quicker car that the 993 at the time and as we know, nothing is allowed to top a 911 in the line up.

I have not started any work on the S2 yet, and I do have a spare 968 engine so the most sensible thing to do is modify that and put that in the S2, however I would like to see what I can get out of an S2 engine without spending silly money.

 

[zcacogp]

ORIGINAL: Tam Lin

I just don't get why a relatively nice hemi 16v head, safe to 7000 rpm, is producing around 57 BHP per litre.

S2 is 3 litres and 211 bhp. Equals a smidge over 70bhp/l.

Not great, I'll grant you, but not as bleak as 57.


Oli.

 

[charles.y]

How come that the available supercharge mod (from 9m) to the S2 is that so expensive £5k-6k. Surely the h/w itself should be easily obtained with a reasonable cost? I personally will consider a well proven supercharge solution if the all-in cost is less than £2k but that I could be dreaming.

 

[Neil Haughey]

Problem with Rotrax superchargers is they are designed as simple bolt on to standard cars and only produce a few psi of boost, there are kits out there for golfs etc that are much cheaper then the 9m kit.

I have pondered this one a lot and I believe a neat way to do it would be bolt on rotrax or similar SC, no IC as you won't need it and swing the inlet cam back 20 degrees and run the engine as a miller cycle. TBH I don't believe the cost would be worthwhile, you would probably only get 270 to 280 Bhp and will still need a completely remapped engine management.

Costs are always the problem though, any of these routes would likely cost more then converting an S2 into a turbo using a 2.7 NA head and everything else from a 951 + custom rods.

 

[Peter Empson]

I can't comment on the last 9M conversions as they're quite different, but the supercharger in my kit (SFR and early 9M) costs in the region of $3,500 in the US when I last checked, so that helps explains why the complete kit is in the region of $5,000 from SFR.

Even if you got the SC for a lot less, on the 9M cars there's apparently a couple of days on the dyno which isn't cheap. Add a limited market where even a cheap SC kit is going to cost as much as an entry level S2 and you can see why demand is unlikely to be sufficient to make decent returns on the development costs. []

Back on topic, has anyone any experience or prices of the Milledge intake?

 

[333pg333]

ORIGINAL: Peter Empson

I can't comment on the last 9M conversions as they're quite different, but the supercharger in my kit (SFR and early 9M) costs in the region of $3,500 in the US when I last checked, so that helps explains why the complete kit is in the region of $5,000 from SFR.

Even if you got the SC for a lot less, on the 9M cars there's apparently a couple of days on the dyno which isn't cheap. Add a limited market where even a cheap SC kit is going to cost as much as an entry level S2 and you can see why demand is unlikely to be sufficient to make decent returns on the development costs. []

Back on topic, has anyone any experience or prices of the Milledge intake?

hehehe, Peter that intake comes under the addage "If you have to ask to how much it is you can't afford it" [] Apparently you need a letter from your Bank Manager.
If you go into that link it shows the whole box and dice for $5600 but from what I've always heard, he wouldn't sell it unless you were buying one of his motors which range from $30k - $50k+

 

[Tam Lin]

ORIGINAL: PJS917
however I would like to see what I can get out of an S2 engine without spending silly money.

Medium term, me too, so if you find a solution that would be cheaper divided by two or three, bear me in mind.
There must be a way of getting more at the top end, without "selling it and buying a turbo" []

 

[Peter Empson]

ORIGINAL: 333pg333
If you go into that link it shows the whole box and dice for $5600 but from what I've always heard, he wouldn't sell it unless you were buying one of his motors which range from $30k - $50k+

Thanks Patrick, now you mention it I remember reading that on Rennlist a while back, it certainly goes to expain why you don't see people using it.

 

[os951]

Everything can be done if you have enough money. 16V engines have far more potential than Porsche ever took from them. Just compare to time perioid BMW E30 M3 engines, latest evo versions had 2,5L capacity, similar Motronic with AFM and far more power than S2 engines.So ITB's can be adapted to 16V Porsche engines even with oem Motronic, needs some fine tunig to the chip, would also be good to change to MAF/MAP or both, like Vitesse racing use in their V-Flex systems.

 

[944 man]

It was developed as a forced induction engine; hence their not spending as much time as BMW fettling the ports/chambers (though theyre good) and camshaft profiles.