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Porsche 944S (with re-bored cyl head)
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Author:  sparkyC [ Tue May 25, 2010 4:19 pm ]
Post subject:  Porsche 944S (with re-bored cyl head)
Hi,

I'm a newbie - bought a 944S a month ago as a project. The body is perfect - the engine is a nightmare, but I knew this when I bought it, and as I said its a project....
My car is a early 1987 944S, the bloke before me had some kind of serious engine failure resulting in the following:
Head re-bored (presumably to 2.7l dia) - cylinder liners added
New pistons (presumably 3.0l - see below)
New 3.0l crankshaft (so its bore and stroke are increased)
New BE and MB fitted
Valve replaced/seats reground (all of this cost £2400 in 2008) ...... 800 miles ago!
The result is a car which starts/runs perfectly normally until around 3500 revs when it hunts and bucks wildly. The only other symptom is a wildly erratic idle speed which does not always keep the engine running.

Here's what I have tried so far starting with cheap things obviously:
97ron petrol (no change)
Redex (to increase combustion/clear deposits - no change)
Injector detergent (to clean injectors- no change)
I have replaced the Air Flow Meter at a cost of £150 (no change)
I have had it checked twice by a "german car specialist" garage in Coventry (no names - no change - not sure they know what to do next but they replaced vacuum pipes, Haws sensor wiring- cost £150 so far)

I have this gut feeling that its as simple as the 2.5l fuel injection system is not man enough for the enlarged engine size.....but dont know enough. I have done some research which suggests the 2.5 system was replaced in 1987/8 with a better Bosch system coinciding with the launch of the 944S2.

Can someone put me out of my misery? I dont need a lecture about buying old cars with bad engines - I knew this going in and dont mind spending the money - the car looks and handles beautifully - it needs to be saved from the scrap heap.

Also my chosen garage has a scrapped S2 sitting in the workshop....... they are just waiting for me to take the risk rather than them.

Any suggestions?

Sparky
Author:  tr7v8 [ Tue May 25, 2010 5:12 pm ]
Post subject:  Re: Porsche 944S (with re-bored cyl head)
OK heads don't get rebored, blocks do. If it has been rebored with 2.7L pistons with a 3L crank then it is 3Litre.
If it has liners, then it has had a lot of money spent on it. Linering is very expensive, Perfect Bore want around 1600quid to do a 944 block :shock:
Assuming it is as you say & it would be cheaper to swap engines than do this level of rebuild & given the value of a 944S then I doubt that anyone would do it, then it will need hugely modified fueling. My suggestion would be to get it remapped by someone who knows what they are doing like Wayne Schofield.
But before you do get it checked over to find out EXACTLY what has been done to it.
Author:  sparkyC [ Tue May 25, 2010 5:50 pm ]
Post subject:  Re: Porsche 944S (with re-bored cyl head)
Thanks Jim,
I have the bills for the work done in 2008 - £2400 ! So the owner must have been mad. He lived with the problem for another 2 years and only covered 800 miles.....even MOT'd it twice!! Wayne Schofield looks like an expert and might be overkill - I just want a functioning 944 not a race prepared one... any other suggestions in the Midlands somewhere? It sounds like replacing the Injection system and EMU from an S2 wont really help then... are you saying the old system with a reprogrammed chip is the better option?

Sparky
Author:  tr7v8 [ Tue May 25, 2010 6:27 pm ]
Post subject:  Re: Porsche 944S (with re-bored cyl head)
sparkyC wrote:
Thanks Jim,
I have the bills for the work done in 2008 - £2400 ! So the owner must have been mad. He lived with the problem for another 2 years and only covered 800 miles.....even MOT'd it twice!! Wayne Schofield looks like an expert and might be overkill - I just want a functioning 944 not a race prepared one... any other suggestions in the Midlands somewhere? It sounds like replacing the Injection system and EMU from an S2 wont really help then... are you saying the old system with a reprogrammed chip is the better option?

Sparky

DME for the S2 has different wiring & sensors so would be quite complex to swap. Better to get the 2.5 DME remapped. Not sure you may need bigger injectors to give more fuelling.
Author:  lindsayhbrown [ Tue May 25, 2010 8:31 pm ]
Post subject:  Re: Porsche 944S (with re-bored cyl head)
Don't know where abouts in the midlands you are but EMC on 0121 328 2225 have a good reputation on 944/968 and are reasonably priced, the do a lot of race prep, but also service/repair too
Author:  sparkyC [ Tue May 25, 2010 8:40 pm ]
Post subject:  Re: Porsche 944S (with re-bored cyl head)
Thanks to you both - will try EMC and let you know.

Sparky
Author:  J.J. [ Wed May 26, 2010 5:51 pm ]
Post subject:  Re: Porsche 944S (with re-bored cyl head)
EMC are a well respected independent. They are not experts in mapping. Jims right. If you want the car to run as it should you need to get it to Wayne Scholfield. (You can drive up the night before & B&B) I know others that could get it near but they will cost you the same & he will get it right. It was £300 before Christmas & thats money well spent. I'm amazed it runs at all with the original DME. Be very careful. Engines get destroyed all the time by people who don't know what there doing! There are more numptys out there with laptops & some dodgey software than engineers that understand what there doing. Your biggest problem will be getting hold of him as hes so B' Busy!! :)
One other bit of advice. Join Tipec. The guy you bought it off should have. Then he would still have it!
Author:  sparkyC [ Thu May 27, 2010 2:57 pm ]
Post subject:  Re: Porsche 944S (with re-bored cyl head)
Joined TIPEC yesterday (the website didnt allow debit cards anymore and I dont do Credit Cards). I already booked with EMC, Kevin the owner is not convinced that you can still fit a 2.5 head on a rebored to 3.0 block ie 104mm dia cylinders (thinks the head gasket etc will overhang). Thinks they might have used a 3.0l head and just not billed for it. Although I hear there are extra water holes etc so will take Jim's advice and get it checked out to actually find out what the other guy did first. Also EMC say it might be as simple as replacing/recalibrating the Air Flow Meter - which I just bought new for a 2.5l!

I never got an answer from anyone on whether the injectors are big enough even with a different DME, so I will take it to EMC first for an investigative partial strip down before going to Wayne Schofield if I have to.

I need a trust-worthy local mechanic in any case. Not happy with the Coventry guys

Will let all know the result next week.

Sparky
Author:  tr7v8 [ Thu May 27, 2010 3:50 pm ]
Post subject:  Re: Porsche 944S (with re-bored cyl head)
Sounds good Sparky, I'm pretty convinced the head don't fit as well. I reckon it is a 2.7 head.
Finding out exactly what was done will be the first thing!
Author:  J.J. [ Thu May 27, 2010 7:27 pm ]
Post subject:  Re: Porsche 944S (with re-bored cyl head)
Well done! What happens really does depend on the engine spec. If they have put a 2.7 head on then it will need a remap to get it right. You will have the 2.7 manifolds that will peg HP to around 180 But the torque of the 3 litre S2. Quite interesting to drive. Don't bodge it for the sake of a trip to Milnrow. Only a remap will get the timing & fueling right throughout the rev range. Difference could be as much as 30hp. If it needs bigger injectors to get it right Wayne will advice. Supply & fit if necessary. What makes him different is he doesn't just remap but debugs the car first. Think you will have a lot of fun with it when it's sorted out! Let us know how you get on.:D
Author:  lindsayhbrown [ Thu May 27, 2010 9:30 pm ]
Post subject:  Re: Porsche 944S (with re-bored cyl head)
If its a 944S it will be a 16v head, so not a 2.7 head as thats 8v, maybe a 3.0 head then
Author:  944 Man [ Fri May 28, 2010 2:40 pm ]
Post subject:  Re: Porsche 944S (with re-bored cyl head)
tr7v8 wrote:
Sounds good Sparky, I'm pretty convinced the head don't fit as well. I reckon it is a 2.7 head.
Finding out exactly what was done will be the first thing!


The permutations are manifold! Thisd be a 3,000cc 8v then... With machined pistons itd be great for a 968 Turbo S, assuming its built properly.

Whatever it actually is: the fuelling and ignition for a 2.5 S will be way out...
Author:  MisterGT [ Fri May 28, 2010 4:20 pm ]
Post subject:  Re: Porsche 944S (with re-bored cyl head)
If you post a pic of the engine it would certainly clear up the question of which head it has, as the Lux/2.7/turbo head is visually very different to the S/S2 head.

Howard
Author:  944 Man [ Sat May 29, 2010 11:10 am ]
Post subject:  Re: Porsche 944S (with re-bored cyl head)
'Lux' was a trim level only. All UK 944s were Lux models, UK 924s were available as base and Lux, as were all European 924/944 models.
Author:  Pixie*Porsche [ Sat May 29, 2010 11:58 am ]
Post subject:  Re: Porsche 944S (with re-bored cyl head)
Hope you keep us all updated, I'm interested to know what happens. Don't think I can really add anything at this moment in time but I think once you get the fuelling sorted the car will be really good fun :D

Good luck with it!
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