Member postings for Peter Seymour-Howell

Thanks for explaining that Michael..

regards

Pete,

hmm.. guys.. the shaft does not have the Uj's as found on a car with a prop shaft, hence it loses less power than a car with a prop shaft.. The shaft is also lighter and thus less rolling mass. NO play from the U/J's and lighter makes a big difference on power loss from the engine to gearbox and thus to wheels It's years since I've played around with prop shafts but IIRC they are pretty heavy and large in diameter, 2, perhaps 3 inches? The solid shaft on the transaxle cars is only 1" diameter, ok it sits in a pretty substantial tube but that is not part of the turning mass, a lot of power is lost through a U/J.

BTW this tube adds a lot of strength/rigidity to the chassis, for example, you could remove the body and the rest of the components would remain upright just as with cars with separate chassis and body., it's also a huge safety factor, again IIRC back in the 80's the EU NCAP tried to enforce stricter safety rules in how high a speed, occupants in a car must be able to survive in a head-on crash. Today tests are performed at a speed of 50kph, the 951 was designed for people to be able to survive a head-on crash above 60 mph, nearly twice the speed of tests performed today. IIRC, only two vehicles ever passed this test before it was dropped as too ridiculous a requirement to put on manufactures. Before this was dropped only two cars passed this stricter test, the 944/951 and I believe the Renault 5 turbo, coincidentally both Homologated as Group B race cars.. This particular feature of the car is fairly new to me so please forgive me if I have any of this incorrect, I don't have the notes in front of me.

I know people who have been involved in very high-speed head-on crashes in a 951 and walk away with little injury, try doing that in any other car from any other period. The secret of the design is the torque tube casing having substantial steel claws which in a crash, grip the chassis tunnel and thus helping to stop the cabin from being squashed in a head-on crash, simple but clearly effective.

Regards

Pete.

I was sitting here thinking how can I show just how good a 951 really is as I know many don't believe it until they actually get behind the wheel. So here's the YT vid I mentioned of the 951 with just 280PS, well he says 270-280 , this is with road tyres and from a guy who learnt the circuit on a PlayStation?.....I have no idea of his driving experience, he's clearly switched on if a little mad... but then he's driving a car that can be trusted, you feel when it's near the limit and it's an easy car to correct when required, not something that most other cars can do in similar circumstances.

https://www.youtube.com/watch?v=_85099hlExA

hmm.. not sure what happened to the text size in my last reply, sorry about that, hope tis one is better?.. I also forgot underbody aero panels.. the 951 is covered in them which are not only designed to affect downforce but also to direct the lowest pressure of air through the intercooler, the air literally gets sucked in due to the front shape and the underbody panels around the engine.

Pete

part 2

The 951 has very long legs, as stated before there are cars in the US with approx 500bhp that have recorded 200mph, as for that matter have cossie Saph's, IIRC at Brungtindon,, sorry can't recall the name of the runway. These things were published in one of the Ford mags a few years back.

Back to the 951, BTW there is a video on YT of a 280 PS 951 doing the ring in just over 8 secs..an impressive bit of driving and at 280, barely tuned. The 174 trip was in a column of cars, a number of which had Sat nav, these are where the speed was recorded, as I said my speedo being the early car maxed out at 170, later cars was 180. The speedo in these cars is out by 6mph from 40mph all the way to max, this has been checked a number of times but as I said, my speedo was bouncing off its pin at the time anyway so not what was used.

I year or so back I had a short run-in with an Audi RS, I never stay at high speed so just play for a few seconds, actually, the last such game was with a new GT3, I had observed him coming up fast in the outside lane, I didn't know it was a GT3 at the time, just that it was a new 911. I waited for his approach, I was doing 95 in fourth, the 951's sweet spot, as he got close I noted he booted it as the car squatted, probably trying to show how good his car was. I waited until he was just about to disappear from my door mirror and then increased power, this was for a few brief seconds only, He got as far as my front wing before my car hit boost and shot past him at over 140 mph at which point I had made my point and backed off. It was only when he passed that I noted the GT3, but then having watched 951's in standard form beat brand new GT3's on the race circuit for some years it didn't surprise me.. BTW, on checking my data log I only actually used 65% throttle, good job the poor GT3 owner wasn't aware of that little fact... I digress,, back to the RS, doing a similar thing to the GT3 but in this case, I missed a gear, not a big deal as I can easily catch but it's what the data log showed and later entered into gear calc that was interesting. I hit 92% throttle, I never rev the engine that high even if it has been designed to do so, max rpm was 7134, this equates to 196mph with the final drive and tyre sizes entered into gear calc, so yes I believe the chaps in the US who have recorded more than 200mph.

The other thing to bear in mind about these cars is they are just as planted on the road at max speed as they are while cruising, something a 911 owner noted while a passenger in my car at 130mph, he couldn't believe the speed due to how solid the car felt, something his own 993 C4 could never do. The aerodynamics of the 951 is leap years ahead of its time, for example, the rear diffuser was the first for any car and is patented for it, this is before such things appeared in F1. IIRC it produces 25kg at 50 mph, ok, not even close to something like the Ferrari F50 but I think you get my point?

There are very few cars on the road in any form that can compete with a well-sorted 951, its handling is supreme and recognised so by those who were involved with racing development in Porsche, giving the early car the highest praise, but then the 951 was a race car before it was a road ca and as I think I pointed out, is a registered Group B race car. It truly is a one of a kind type of car, a very special car and I know many Porsche enthusiasts who have sold their 951 in search of the iconic 911 only to regret it and either sell the 911 for another 951 or own both. When challenged to which is the best though, it's nearly always the 951.

Anyway, that's enough rambling from me, lets just say that I am very confident in the car's ability, it's just after 5:30 am here and I should be asleep..

Cheers

Pete

hi Steve

Pretty much so although the Cossie hasn't been on the dyno yet, the work has been done by a top outfit or so I'm told, I'm not into Ford's these days so a little out of touch.

As for my own car, very confident in the figures given, I used to be very much involved in the 944 Turbo UK league. Details can still be found on google, back then the car was the 5th most powerful in the league, this was at only 368bhp, the top car being over 400, figures that were proved numerous times on a number of rolling road sessions across the country. Such sessions were closely monitored for the accurate shoot-out setting to ensure we always had factual figures, it's very easy to trick rolling roads. This is going back nearly 15 years and the car has been developed a hell of a lot further since. The last round of upgrades cost over £12k in parts alone, machining is done by Serdi UK. Compared to the guys in the US, my car is only mildly tuned, there are plenty of YT vids with details..

174mph with 282bhp, easy...a few things to note, the 951 came in two guises, the 220bhp with Porsche stats giving it a top speed of 152 and the 250bhp with stats at 162. Now Porsche always gives lower figures than a car actually does, for example, all road tests of the day achieved higher performance figures in both acceleration and top speed, the 220 coming in at 159mph. Ok, so we need to note a few things about Porsche, from day one they did all they could to keep the 951 slower than the 911, at the time they said this was to make the car easier to drive, to do this the boost was allowed to leak long before the car actually hits max boost (which btw was 0.75 and 0.82 bar for the two variants) and the engine was never allowed to hit the redline in higher gears, this is a fact. Even after this attempt by Porsche they themselves admitted in the late '80s, early 90's that the 951 was the fastest car in the fleet, this included the 911 turbo. With A DPW fitted, this alone changes everything and allows a red line in all gears, even without extra power the car will be much faster.

end part 1

Ah.. yes electricity, has its own issues, safety is one although perhaps not as bad/often as fuel. EV's are the future, there's a video on YT of a guy who's converted his IIRC 951 (could be a normal 944?) to electric and then put it up against the latest McClaren on the dragstrip. Well, let's just say that not only did the 944 win but evidently it won by a bigger margin than any car before it against this brand new McClaren. I don't think that we will see the end of IC engines though, certainly not Porsche who have teamed up with Siemens to produce their own zero-emissions fuel to keep all old Porsche's on the road. IIRC they will be testing it either later this year or early next and have invested other £1 billion into new factories/plants to produce this new fuel.

They are also very much into electric and again have joined a partner (can't recall who although could be Seimens again) for electric flying cars which on being developed as we speak.

Pete

Pete

Thanks Steve... I saw them...didn't know how to acknowledge.. should have just said so here..lovely cars.. I'm intrigued..what's the story with the Tesla?

Hi Tim and Jason, my apologies chaps, you are of course, correct which is a bit worrying for me as clearly my mind is worse than I thought? That's another story which I don't want to bore you guys with my health issues.

I have just reread my notes and yes I did state that it's the CR that is affected not displacement...sorry about that and thanks for putting me straight.

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

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

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

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

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

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

regards

Pete

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

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?