Porsche 951

Thanks, Dave

I know what you mean about getting in and out, I also find it difficult these days. No problem with the cockpit being tight though, lots of room in these cars with their fairly modern design. The earlier 944 was more difficult as its steering wheel sat much lower making it difficult for taller gents. This was corrected for the 86 model year when what's known as the 'oval dash' model first appeared.

I used to also believe that the 944 engine was basically half of a 928, recent reading has changed that view a little but the jury is still out.. There are a lot of similar parts though, IIRC they have the same stroke too. I've had 5 adults in my car, the result of giving 3 girls a lift home from a night club late one night, with my mate sitting on the tunnel in the rear with his head through the roof... he didn't complain, he had two beautiful girls to sit between.

Having been in the back of a 944 I would say it's only for very short people, I say that as someone who's under 5' 8"... This was while at Le Mans when a group of us decided to go to the pub in one car, never again....

Pete

Nice to seeing you using her as intended, great engineering is made to be used and enjoyed

A neighbour of mine worth millions has an e-type stashed in a garage somewhere doing nothing, going nowhere, wasting away its existence as an investment I presume

thank you, IMHO a garage queen is only good for one thing, sitting in a garage. Start driving it and it will soon break down. I love the E-type, perhaps the most beautiful car in the world, I put the 951 right behind it in looks. A good friend/old work colleague of mine has an E type which he fully restored, it was he who got me into Porsche when he persuaded me to drive his own 951. Up until then, I had been a fast Ford man. Today he builds Bugatti's, not replica's per se but real cars built to the original drawings, the coachwork has been a challenge as no drawings exist. Last time I visited he was building a Bugatti Royale, an enormous car which IIRC has a locomotive type Bugatti engine in it? I recall seeing the engine castings sitting on a pallet ready to be shipped to holland for machining... no cylinder head, all built-in one with the block.

No mention of the actual engine size?

ah, sorry about that...

originally 2,479, now IIRC 2,532 ( i would have to dig out my calculations). This is due to the larger bore, deeper dished pistons, and thicker multi-layered steel head gasket. Again, IIRC, this keeps the compression ratio close to its original of 8:1, perhaps slightly higher?

Stunning car you have there. Way back i did quite a bit of mods to porsche cars. My 1st was i built a Covin fibre glass replica of a 911 turbo flatnose. The kit cost me £3000 from Covin in south woodham ferrers . It used a Beetle platform which i cut 6.5" from its wheelbase. Then welded it back together. Not happy with that i made a 25mm x 25mm chassis of which was welded to the underside of the Beetle platform. I bought a wrecked 911 2.4 litre flat 6 engine & rebuilt it. This was grafted to a Transporter gearbox. I kept it for a while & sold it & bought a 924. Which i fitted 944 wings at the front & replica glass fibre ones to the rear. Will try & find some pics of it. Dissapointed at the lazy 924 audi 2.0 engine i sold it on. Later i bought a 911 carrera 2 3.6 litre 231 hp . But was dissapointed again as i had a Nissan Sykyline GTR33 vspec running nearly 700 BHP. So the Porsche was a bit flat. Unfortunately i at the time could not afford a 911 turbo which was my aim. Many cars since i now have my dream car. When i was in my early 20's i had an Etype 4.2 series 2 drop head. So when the Ftype came out i prommised myself one when finanaces allowed. Now i have one the Dam Coved has stopped me enjoying it for nearly 18 months now. This is the 575 Bhp v8 which was chipped with the SVR map. I have it booked into Appleby engineering who are going to change the Supercharger pulleys to get the most from the Eaton charger. They are also going to fit the 200 cell race Cats. So hoping for around 630BHP. Still way short of my Skyline , but instant power over the Nissan twin turbo's. Some pics here.

Steve.

Edited By Steviegtr on 11/05/2021 01:01:00

Lovely cars Steve, I thought that I had it bad but you have clearly been bitten by the modified bug far worse than I....🙂

The Beetle/911 is very convincing...very impressive sir..

My son's are worse than me, I have no idea where they get it from..son No.2 is the worse, he's had a number of Fast Fords over the years, he's just bought himself an RS Focus with 350bhp, he was going to leave it alone but evidently a 911 showed him it's heels last week so he's now going to boost it a little. He's always telling me that his cars will beat mine but after being beaten by this 911 he knows the Focus isn't as he's seen mine leave 911's, including turbo's and recently a new GT3 for dust.

I used to be an avid follower of the 951 on the race track admiring just how quick it was in the Porsche Cup series. Alas after watching some great racing in the late 90's early 2000's Porsche banned the older cars from the series as they kept beating their brand new models. After trying many things with handicapping Porsche then entered the fray with the then brand new 996 GT3. In the last season the field included 13 GT3's with not many 951's or older 911's still in the series. The final straw came when the championship was one by an old RS 911. Interrestingly the car with the most wins was Chris Heeley's 951, it also had a lot of DNF due to mechanical failures so only got 3rd overall. At this point Porsche had had enough of 25 year old cars beating their brand new models and made the series GT3's only.

The most impressive thing about this is the engines had to remain standard, just goes to show how good the 951 is and why Porsche themselves when a current model rated it as the fastest car in the fleet, at that time this included the 928 GT and 911 turbo

Going back to my son, he may have been outdone by this fat 911 but if he had been in his other car it would have been a different story altogether. His real pride and joy is his Ford Escort Cosworth which has a lot more power then my 951, IIRC around 600bhp and it is in mint condition having been fully restored and painted by my eldest son's business partner who is superb, hopefully, the same chap who's painting my car this year.

I'll try to post a picture of the cossie later..

Regards

Pete

here you go steve, my son's 'Cossie'

regards

Pete

Capacity is bore and stroke multiplied by the number of cylinders, no other factors apply.

well yes but HG thickness also plays a part as well as how many times the head and block have been skimmed down... I've dug out the figures worked on at the time... the gasket was changed for thicker again later once the head had been skimmed and thus increased the cc a little further.

This has been copied from my build page on the official Porsche forum

Quote:

Displacement = 101 x 78.90 (10,1 x 10,1 x 3,1412 / 4 * 7,89) = 632.05cc ( considering deck as 0) per cylinder with a total displacement of 2,528.2cc... nice..
Head = 55cc (standard approx)
Piston volume dish= 26.0cc

101x0.70mm gasket = 5.6cc (aprox)
CChamber = 55 + 5.6 +26(piston dish) = 86.6cc

Therefore: 632.05 +86.6 ) / 86.6 = CR 8.26:1(using a 0.70mm gasket)

End Quote>

Note, in this calculation, I used measurements from a standard head, the stage 2 head chambers were measured later once it had been stripped down and rebuilt.

Also as I recalled, the CR is slightly higher than the 8:1 on a standard car., or should I say 'lower'

Regards

Pete

Lovely Cossy escort. The nearest i got to one was my 1988 Saphire Cosworth. It was the 1989 Pace car for Brands Hatch. But was no where near your Sons power. I think from memory it was running 22psi with grey injectors. Around 300 BHP. I will post some more pics of cars i have had , but rather than spoil your thread i will put them in my Albums. So keep having a look . It may take a while as they all need scanning from Photo's. I think one of the nice things about the Porsche you have is that they seem to be timeless. Always fancied an S2 soft top. Never happened.

Steve.

Ah.. yes my son has had a few Saph cossie's too, one of which was featured in Fast Ford, I think, it was on the front cover, must be a good few years ago now.. IIRC he didn't own it at the time, bought it shortly after.. think it had 500 in the reg somewhere?

I'll keep an eye open for your other cars...

Pete

Head gasket thickness has no effect on the swept volume (or capacity if you like). What it does affect is the compression ratio.

And if the combustion space is decreased, the compression ratio goes up.

Cheers, Tim

Hi Tim

Hmm, I'm not sure that is correct, I mean to take things to the extreme if you had a 5 mm thick HG, that is going to increase your overall volume if everything else remains the same. We are not talking normal HG's here, I have a multi-layer steel gasket to hold the increased boost which is more than double the original, it doesn't squash when torqued down..

The figures given in my previous post stated an HG thickness of 0.7mm, this was a 3 layer steel gasket. The final HG used was a 5 layer 1.52 mm thick gasket due to the machining of the head, this is actually a little larger than required but the closest available off the shelf, well it was a special from the US but one that they could easily accommodate. The IASA full-spec race pistons have a different sized dish to the Porsche pistons which also has an effect on the cc/CR.. It's 6 years since the rebuild so my mind may be a little fuzzy but I think that covers it?

Regards

Pete

Regarding the CR, yes, if space decreases the CR increases

I wonder if you are confused by the term 'capacity' ? Engine capacity is really a confusing term, as engine size is measured as the volume of mixture which would be taken in under ideal conditions, in one full rotation. Swept Volume (swept by the moving piston) is a much clearer term. It doesn't matter how thick your gasket, or how much you plane off the head or block, the swept volume does not change. Honest. I'm not a betting man, but I'd put money on that statement.

Cheers, Tim

Wow what a stunning car, nice work done on the restoration Peter.

A few pictures of the engine under construction, here's the ladder cradle that holds the crank, the pressed steel plate along one side is the crank scraper, this alone has a significant impact on throttle response by ditching all of the oil that sticks to the crank while running. It also solves the one flaw in this engine when racing, that being during hard cornering the oil gets aerated around number 2 rod, the scraper removes that issue.

One of the secret weapons on this engine, the two balance shafts that give this big 4 pot the same smooth running as a straight 6.

The head and cam tower now fitted, there are a number of mods done to this engine that are not visible. The pistons I have already mentioned, as stated they are full race, the rings are tiny to reduce friction and improve response.. There is also an extra groove below the compression ring to allow the piston to hold much more boost before any blow-by occurs.

The studs and bolts are aero-spec and can hold much more pressure than the Porsche originals, the steel HG ensures nothing lets go.

The cradle has an extra pin added to help in getting the crank spot on in alignment and keep it there under full load.

And the bigger turbo, this is the super 61 which is capable of developing 620 bhp at 1 Bar, not on my engine though, would need more capacity to hit those figures at only 1 bar.

The turbo is both water and oil-cooled and includes a 30-sec cooling time to negate carbon build-up after switching the engine off, which is standard on these cars.

The engine is currently running at a max of 1.5 BAR, (set via ECU overboost ), the red line is 7200 and the ECB has been set with a high duty cycle to remove most of the lag. Other safety factors have been added to tackle the resulting boost spikes from the high duty cycle. Top speed? who knows... She will red line in 5th and hold the boost all the way up there, in theory, that gives a 200 mph+ top end but of course, wind resistance has a say in such things but she does have a low drag coefficient of 0.33 and only weighs 1280KG. Cossie's have been recorded at plus 200 and they are shaped like a brick..

Hopefully, this may help answer some questions..

Pete

Interesting Tim, perhaps I should bring this up on the Porsche forum next time I post, those guys know their stuff although none of them pointed this out when the build was current. I can easily get confused though, especially these days....

Cheers

Pete

You can only increase capacity (displacement) by increasing bore and/or stroke, using a thicker gasket will just lower your compression ration

Edited By JasonB on 11/05/2021 20:57:06