Engine Mod advise / views welcomed

[George Elliott]

I have had this question floating around for some time. I think I am broadly correct in the following background of the 944 and especially the 951.

A less sophisticated than today's, Porsche Cars intention was to develop the 944 and phase out the 911. (They gave a 924 the model designation Carrera GT and took it to Le-Mans successfully). (And fitted air injection to the 911SC[]).
When they were 80% down that route they bottled out, (I'm glad they did - they need the 911). But the 951 had been developed, and it was too good, - but it was too expensive to Can it. With a market for this spruced up 924 selling at £40k in the late 80's, it had to go to market.
To position it in the model Range where it would not show the 911 turbo or 928 up, the 951 had to be restricted, (un-like my old AP50 Suzuki[] - 48mph, or 55 with a strong down-hill tail-wind[] - I digress).

Hence, the 951 has loads of potential to make it the car it could have been.

I would, as I said value comments on how / what restrictive components to modify and replace. The cars had 220/250bhp as standard, and 0.9 bar? boost. The 2.5 four cylinder is bomb proof as we all know.

Recently I have noticed that a few cars have expired, which is sad/expensive, and I suppose I fear for my own.

I have a theory, "the engine is v.strong when new, no wear etc, but as it ages we mod them to produce more power, and because they are getting tired, (or we have a poorly engineered mod) - they pop.

My conclusion is that all the experience I see on here (and other 951 forums) should enable us to develop the car Porsche engineered, and its Marketing bods tried to bury.

I have a plan to build an engine,[>:] but wonder what is the "right spec". It is a daily driver not a drag racer, - Boost pressure must be strictly limited to 1.2Bar. Secondly, rpm is limited to 6800 as I figure the valve train and spark management becomes more difficult above this level. A vented head would eliminate the hot spot at the rear of the Cyl Head which seems to be where many gaskets fail, (mine incl[&:]). The car should be a true Porsche, - quick & reliable, and efficient - 25mpg at constant 56mph.. (Also capable of 12mpg on a hill-climb[]).

So, any comments for the 951-S2 engine spec, or perhaps 951 GT2[8D]. (every component, from the inlet snorkel to the exhaust tip)

I wanted to ask Fen, Sweettea and Indixx especially if that is acceptable, but of course I would appreciate any comments. - except "your mad", I know that.[8|]

George

 

[sawood12]

I'm not sure about the history. It certainly seems to be the accepted story but what the reality was i'm not sure. One thing is for sure though, Porsche did build the 944 with plenty of robustness built in, perhaps in anticipation of more and more powerful models planned. There are plenty of people running in the high 300bhp and some even over 400bhp with essentially standard clutches and gearboxes that seem to stand upto the power and torque hikes no problems. I'm sure if you hiked the power up by similar levels in a conventional family car the gearbox and clutch would pack up pretty quickly.

There are plenty of threads you can search through on this forum about power hikes, but as a start the boost control system should be your first steps i.e. the wastegate. Proven mods here is to fit a dual port wastegate with a boost controller (preferably an electronic one) and install associated chips and an uprated fuel pressure regulator. This setup can be had for under £1000 and should be good to take a 220t upto and maybe over the 280bhp region depending upon what boost level you decide to run - we'll soon see at the next Weltmiester session!!!! After that the sky and your wallet is the limit. But the first thing to do before you start increasing boost levels is to check you have a good engine.

If you want over 300bhp from an off-the-shelf kit then the Vitesse kit is getting some good press at the moment. The Vitesse stage 3 kit is around US$3500 and is good for 350bhp or even more. Promax also sell a range of off-the-shelf kits to get you to various power levels. If you want to see what is possible then Pauls 3.2 monster and Rick Cannell's ultra-high tech Wuf are examples of two very different ways of getting power and torque levels that would shame many modern, exotic and expensive hardware. Of course though if you up the power levels don't forget about suspension and brakes. It's a viscious and very expensive circle!! You also have to go into this with a view that you will be spending alot of money which you'll never see again, so you have to see it as an expensive hobby and not to expect it to increase the value of your car commensurately.

 

[John Sims]

Hi George,

I believe the intention was that the 928 would supersede the 911 but it doesn't make a lot of difference.

I have also been a believer of the "Porsche Marketing limited the 951" theory. In much the same way they are holding back what might be one of the best cars of today with not putting a Lim Slip and more power in the Cayman. However....Porsche did develop the 951 to achieve it's full potential at the time. They produced the Cup Challenge Cars. These had bigger turbos, increased boost, better brakes and suspension, stronger gearbox and gearbox oil cooler, Lim Slip and other tweaks. These spawned The Silver Rose and subsequently the 250 or SE. It therefore makes most sense to start with a later car rather than a 220 and build it up to 250 spec. I started with a 220 and have matched or exceeded 250 spec in most areas (not the cheapest way of doing it by a long run).

When it comes to expenditure (and initial mods) I agree with Scott 100%. A 951 can quickly become a money pit and will never return what you put in money terms.

Many the 951 provided a massive "bang per buck", but standard cars have developed over the years since the 951 was introduced. I think, you can probably get better value "bang per buck" motors now. If you consider the raft of good second hand hot hatches and exec sports saloons available for £10K you really have to want a 944.

"But I'm not spending £10K on my 944?" you say.........You will.

 

[Neil Haughey]

Yes something like a last gen 540 sport seems one hell of a lot of car for so little money. The lowest price I have seen on a reasonable 540 was in the £5K range, £10K+ gets a late minter. £15K also gets you into a couple of years old monaro, very tempting.

IMHO if Porsche where doing the 951 now it would have an intercooler mounted in front of the radiator (maximise surface area, increase cooling efficiency), and probably one of the high end Garret turbos with an integrated wastegate (vastly better packaging, much broader range at high boost). These differences alone should give circa 300 Hp from a 250 car (every 10 degrees C drop in inlet temp worth about 3% more power by more efficient intercooling, at the same manifold boost reading i.e. lower temp at same pressure = much more air).

 

[wizard]

ORIGINAL: John Sims

When it comes to expenditure (and initial mods) I agree with Scott 100%. A 951 can quickly become a money pit and will never return what you put in money terms.

[]

But you will have a blast and something a little unique.

 

[John Sims]

ORIGINAL: wizard

But you will have .....something a little unique.

You will. A car that has cost you £20K and is worth £5K. Not that that is very unique as I guess it is common to all new cars.

 

[sawood12]

ORIGINAL: John Sims
It therefore makes most sense to start with a later car rather than a 220 and build it up to 250 spec.

I sort of agree with Johns comment above, but if you are intending to upgrade the turbo (maybe as part of a Vitesse stg3 kit), brakes (big blacks), suspenson (KW) all you are left with over the 220 turbo is the 250 turbo's uprated gearbox. If (or maybe when) I had all that i'd be looking to tweak the gearbox as well with a Quaiffe torque sensing diff (or even a Quaiffe diff in a 968 gearbox). Paul has proved that above 300 bhp you will have traction issues, even with an LSD, therefore that's where the Quaiffe torque sensing diff comes in. Once you've done all of that you have replaced all the more desirable components of the 250T. I'm not convinced the oil cooler is necessary unless maybe you are racing the car, but even then modern fully synthetic gearbox oils can withstand much higher temps anyway. They ditched it on the 968 which had 240-odd bhp, so almost as much as the 250t.

By the way in the little mod package i've just described there, plus a few other odds and sods you'd need (DPW, EBC, larger injectors) you are looking at a bill of around £6500 + fitting (and assuming you don't need a new cylinder head gasket or clutch). But you'd have one hell of a 944. Sounds expensive, but the X51 kit on a 997C2S costs over £8k and it only gives you an extra 31bhp, so on a cost per BHP basis it's a bargain.

 

[333pg333]

'Can of worms' comes to mind here.[]

 

[944Turbo]

Standard wastegate and boost control system are weak - especially after 15 years and will throw away power.

Intake leaks will rob you of power.

Incorrect mixture or incorrect timing will destroy your head gasket, so its nice to be able to monitor exhaust gasses and knock.

I believe too much boost will destroy the standard engine through cylinder flexing (or take out the head gasket).

So replace the wastegate sort the leaks, then look to improving the air in and exhaust out, whilst maintaining safe air/fuel mixture and timing. (turbo, IC, head, exhaust, injectors, fuel regulator, fuel pump, chips and MAF or standalone with maf or map. Ensure electrical system in good order plugs/coil/ leads / injector harness / knock sensor. (larger capacity / sps style liners)

renew/uprate suspension brakes.

remove weight.


enjoy

[]

 

[Diver944]

I think if you are going down this route with strict safety in mind then the first thing to do is to replace the head gasket if it is still original. This will also give your mechanic a chance to have a good look at the bores and also the valves and head.

If everything is deemed fine then you need to change the old and worn wastegate to a dual port design that can hold whatever boost you dial in.

Then I would recommend getting a Vitesse MAF kit and piggyback to very nearly give you a standalone engine management system that you can easily and safely tune your engine to run whatever boost you want.

With bigger injectors and running at only 1.2 bar boost you will be easily over the 300bhp level and if you fitted a bigger turbocharger you could be knocking on 350

 

[Neil Haughey]

Guys, one thing with worn wastegates replaced with upgraded items. It has to be added that one needs to be very careful that the wastegate isn't wound up so tight that the engine ends up getting significant back pressure between the turbine and exhaust ports. I don't know if this is a problem on the 951 since I haven't seen it mentioned at anytime over the last 6 years. This can cause a lot of damage that shows up longer term. I know because I used to run a garrett T3 flat out in a different turbo car, against the advice given to me by turbotechnics. Engine eventually died a gradual smoky death that to this day I attribute to the turbo back pressure.

 

[AndrewS]

Hi All,

George and I have discussed this at length already. Bigger capacity equals more torque (as in the Case of John Daly and Paul Smith - 2.8 and 3.2 respectively) - but there are so many ways of raising performance and preserving durability.

The 2.8 is relatively easy to achieve as the standard block and bores can be used (though usually the 100.5mm oversize is required to get maximum life from the rebuilt engine) along with a 3.0 crank.

A 2.7 motor with solid lifters, high boost and direct coil ignition (as well as stand alone) could be a recipe for high HP (through high rpm with more agressive cam profile).

I also spoke to Rick at Bedford about ignition and have discovered (as has George) that there is room for improvement on the standard coil/distributor ignition - especially when making more boost. Rick did suggest this to me last year - I didn't realise how much improvement was possible in that area.

Then of course there is the LS1 V8 conversion - I hope we get round to this one day ;-)

Regards,
Andrew

 

[John Sims]

ORIGINAL: AndrewS
................
Then of course there is the LS1 V8 conversion - I hope we get round to this one day ;-)

Regards,
Andrew

I'm sorry it just doesn't seem the right thing to do. It's like putting a Rover V8 in a GT40 replica - it is wrong.

If you have to have an LS1 there must be better kit cars to stick it in more effectively than into a 944. You could start with an Ultima.

 

[jackregan]

agreed it wont be a porsche engine in a porsche car, but what a scream it would be to drive!

And to have a loud V8 exhaust noise - fantastic! - crack on I say!

 

[Riverside]

ORIGINAL: John Sims

ORIGINAL: AndrewS
................
Then of course there is the LS1 V8 conversion - I hope we get round to this one day ;-)

Regards,
Andrew

I'm sorry it just doesn't seem the right thing to do. It's like putting a Rover V8 in a GT40 replica - it is wrong.

If you have to have an LS1 there must be better kit cars to stick it in more effectively than into a 944. You could start with an Ultima.

I get your point about sticking it in a more effective place but there's a fair number of otherwise good 944 chassis with popped engines, and some owners might prefer this route to breaking an otherwise good car for spares. More choices = a good thing imo.

 

[924nutter]

ORIGINAL: Neil Haughey


....... IMHO if Porsche where doing the 951 now it would have an intercooler mounted in front of the radiator (maximise surface area, increase cooling efficiency), and probably one of the high end Garret turbos with an integrated wastegate (vastly better packaging, much broader range at high boost). These differences alone should give circa 300 Hp from a 250 car (every 10 degrees C drop in inlet temp worth about 3% more power by more efficient intercooling, at the same manifold boost reading i.e. lower temp at same pressure = much more air).

We would also encourage Messers (or is that Herrs?) Porsche to fit the brand spanking new variable vane turbo technology that alters the angle of static vanes in the casing to utilise more of the low rpm exhaust flow to produce useable boost and finaly eradicate the turbo lag of the 951. Hells teeth we might even keep up with LIL for a couple of metres.

 

[DivineE]

Not that I want this to become more of a sales thread but I still have a heavily worked on ported polished etc head for sale which came from a car with 80,000miles on it and has never been used since it was re built. See the parts for sale section above for details. I would be happy to take £850 for it so that would save you a bundle!

Ben

 

[AndrewS]

ORIGINAL: jackregan

agreed it wont be a porsche engine in a porsche car, but what a scream it would be to drive!

And to have a loud V8 exhaust noise - fantastic! - crack on I say!

Hi All,

I have a strong feeling that this might just be a reality some time this year [] - what a flying squad car that would be?

The LS1 is an awesome unit and very, very reliable. Its an easy 400bhp and Roger Keys already has turbocharged his equivalent to ???bhp (it would be rude to talk figures without showing the dyno chart from WRC). That's in a Holden Pick-Up (some of you may have seen it?) Whether there would be room to plumb in the turbocharger for an LS1/944 (or 968) installtion I am not sure.

The reality is, its probably at least £3,500 to rebuild and fit a new 951 engine (i.e, rebuilt with new rings, freshly prepared bores etc, new bearing shells, oil pump etc.). It could be cheaper to fit an LS1 depending on source of engines and the actual cost of the parts to get it to fit to the 944 Turbo transmission etc.

Personally, I can understand the purist view. However, I very much like the V8 in a 951 concept.

Regards,
Andrew

 

[Neil Haughey]

You mean like this one here:
http://www.midlandturbo.com/

Something like a gt30r seems to be pretty hot stuff.
I know its a different car but check this out,
http://www.maptun.com/cars.php?id=212

 

[Neil Haughey]

ORIGINAL: Neil Haughey

You mean like this one here:
http://www.midlandturbo.com/

Something like a gt30r seems to be pretty hot stuff.
I know its a different car but check this out,
http://www.maptun.com/cars.php?id=212

Forgot to add that this is what the gt30r looks like, no idea how much that is in GBP.
http://www.maptun.com/webshop/shop_info.php?id=1193&rubrik=31&kategori=78