Engine Durability of Tuned (400+ WHP) 951's
05-29-2023, 06:50 PM
#197
Burning Brakes
Nick, thanks for your feedback - I welcome comment about other people's experiences with their build.
Robert Gant told me ages ago that when you're looking at modified cars, each build is unique as they may share a number of parts but the precise combination of parts is often quite different. Then we've found challenges with packaging for RHD as many of the aftermarket parts are made for LHD. If you run the calculations of the airflow required for a given power level then you become aware of exactly what size air filter will flow the required amount. Fundamentally VE is king - boost or more specifically pressure ratio is merely a measure of restriction - obviously the higher your VE the greater the power for a given level of boost.
We'll see - but as I've said before - factory levels of durability & reliability mean more to me than another 100 bhp.
I still maintain that a high quality modified road car should take its tuning cues from a 24 hour endurance racer rather than a WTAC type car. Has anyone on these boards raced a 951 in a 24H race like BritCar or the N24? I'd like to hear how someone with that type of car dealt with lubrication, oil cooling, cylinder head temperatures, transmission cooling etc. To me a car that can race for 24 hours at 450 fwhp is of more relevance to me than a wet-sumped, alusil bore, 16 valve with produces 650 fwhp - but after two hard laps of the Nurburgring it is done - with soaring oil temperatures, potential HG damage & concerns about oil foaming & No.2 conrod bearing damage.
Robert Gant told me ages ago that when you're looking at modified cars, each build is unique as they may share a number of parts but the precise combination of parts is often quite different. Then we've found challenges with packaging for RHD as many of the aftermarket parts are made for LHD. If you run the calculations of the airflow required for a given power level then you become aware of exactly what size air filter will flow the required amount. Fundamentally VE is king - boost or more specifically pressure ratio is merely a measure of restriction - obviously the higher your VE the greater the power for a given level of boost.
We'll see - but as I've said before - factory levels of durability & reliability mean more to me than another 100 bhp.
I still maintain that a high quality modified road car should take its tuning cues from a 24 hour endurance racer rather than a WTAC type car. Has anyone on these boards raced a 951 in a 24H race like BritCar or the N24? I'd like to hear how someone with that type of car dealt with lubrication, oil cooling, cylinder head temperatures, transmission cooling etc. To me a car that can race for 24 hours at 450 fwhp is of more relevance to me than a wet-sumped, alusil bore, 16 valve with produces 650 fwhp - but after two hard laps of the Nurburgring it is done - with soaring oil temperatures, potential HG damage & concerns about oil foaming & No.2 conrod bearing damage.
If you want to race at 450hp for 24 hours the same short block will be a lot more reliable with a 16v head simply because (as you point out above) there is less resistance with higher VE and as such pumping is more efficient. The engine makes more power at less boost and everything is much happier, less stressed, cooler, heads move less etc.
My initial point was just to highlight that you could end up with a very narrow power band on an 8v with a turbo that spools up at 4k and this will work against your goal for good torque spread. If you stick with this turbo (you have to start somewhere) you need to focus on spool. Have the option to easily switch to the smaller housing (0.63), look at good quality turbo blankets. Anything you can do to help. Hopefully the 2.7 will be a little keener to rev than the 3.0.
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Noahs944 (05-29-2023)
05-29-2023, 06:50 PM
#198
Rennlist Member
Thread Starter
Thom, I don't agree that the Italians do V12's best - I cannot recall reading of any Italian V12 which has covered 300,000 miles without a rebuild.
There is Murcielago here in the UK run by Simon George which has done almost 300,000 miles but it's on its second block, had about five top end overhauls and and a couple of bottom end rebuilds - there's very little if any, of the original engine left - to me that is not quality engineering:
https://www.pistonheads.com/news/ph-...h-heroes/36026
There is Murcielago here in the UK run by Simon George which has done almost 300,000 miles but it's on its second block, had about five top end overhauls and and a couple of bottom end rebuilds - there's very little if any, of the original engine left - to me that is not quality engineering:
https://www.pistonheads.com/news/ph-...h-heroes/36026
05-29-2023, 07:06 PM
#199
Rennlist Member
Thread Starter
Nick, to me it's a tuned 944 turbo - not a fast car by modern standards, but hopefully respectably quick, durable & reliable for an old four cylinder Porsche.
If you look at a modern car like the M2 Comp with the S55 - a 24 valve, twin-turbo, six cylinder - its potential is enormous - with E85 the Pure Turbo's Stage 2+ kit it is approaching 800 whp.
Given that my 952 is so easily out-classed by quite modest modern machinery - to me it's not worth spending any more money on it - I just want it to be reliable for extended track sessions (up to 45 minutes) at the faster European tracks.
As I've said before, a 2200+ kg luxo barge with five people on board & their holiday luggage (Mercedes S65 / BMW 760 Li / Bentley Flying Spur Speed / Rolls Royce Black Badge Ghost) will take apart my 952 in a straight line, so it's not worth getting too upset about its performance or lack thereof.
If you look at a modern car like the M2 Comp with the S55 - a 24 valve, twin-turbo, six cylinder - its potential is enormous - with E85 the Pure Turbo's Stage 2+ kit it is approaching 800 whp.
Given that my 952 is so easily out-classed by quite modest modern machinery - to me it's not worth spending any more money on it - I just want it to be reliable for extended track sessions (up to 45 minutes) at the faster European tracks.
As I've said before, a 2200+ kg luxo barge with five people on board & their holiday luggage (Mercedes S65 / BMW 760 Li / Bentley Flying Spur Speed / Rolls Royce Black Badge Ghost) will take apart my 952 in a straight line, so it's not worth getting too upset about its performance or lack thereof.
05-29-2023, 07:18 PM
#200
Burning Brakes
Nick, to me it's a tuned 944 turbo - not a fast car by modern standards, but hopefully respectably quick, durable & reliable for an old four cylinder Porsche.
If you look at a modern car like the M2 Comp with the S55 - a 24 valve, twin-turbo, six cylinder - its potential is enormous - with E85 the Pure Turbo's Stage 2+ kit it is approaching 800 whp.
Given that my 952 is so easily out-classed by quite modest modern machinery - to me it's not worth spending any more money on it - I just want it to be reliable for extended track sessions (up to 45 minutes) at the faster European tracks.
As I've said before, a 2200+ kg luxo barge with five people on board & their holiday luggage (Mercedes S65 / BMW 760 Li / Bentley Flying Spur Speed / Rolls Royce Black Badge Ghost) will take apart my 952 in a straight line, so it's not worth getting too upset about its performance or lack thereof.
If you look at a modern car like the M2 Comp with the S55 - a 24 valve, twin-turbo, six cylinder - its potential is enormous - with E85 the Pure Turbo's Stage 2+ kit it is approaching 800 whp.
Given that my 952 is so easily out-classed by quite modest modern machinery - to me it's not worth spending any more money on it - I just want it to be reliable for extended track sessions (up to 45 minutes) at the faster European tracks.
As I've said before, a 2200+ kg luxo barge with five people on board & their holiday luggage (Mercedes S65 / BMW 760 Li / Bentley Flying Spur Speed / Rolls Royce Black Badge Ghost) will take apart my 952 in a straight line, so it's not worth getting too upset about its performance or lack thereof.
05-29-2023, 09:08 PM
#202
Addict
Rennlist Member
Rennlist Member
Dry.
The new all-Porsche powerplant was first seen in the 924 Carrera GTP in 1981 (above), a motorsport machine entered in the GT prototype class at the 24 Hours of Le Mans that year and subsequently regularly referred to as the 944 GTP Le Mans. In fact, this racer’s engine was a mishmash of components, using the aluminium block of the forthcoming 944, including its balancer shafts, with a bespoke double overhead camshaft cylinder head and dry-sump lubrication, plus a KKK turbocharger.
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Noahs944 (05-30-2023)
05-30-2023, 03:45 AM
#203
Thom, I don't agree that the Italians do V12's best - I cannot recall reading of any Italian V12 which has covered 300,000 miles without a rebuild.
There is Murcielago here in the UK run by Simon George which has done almost 300,000 miles but it's on its second block, had about five top end overhauls and and a couple of bottom end rebuilds - there's very little if any, of the original engine left - to me that is not quality engineering:
https://www.pistonheads.com/news/ph-...h-heroes/36026
There is Murcielago here in the UK run by Simon George which has done almost 300,000 miles but it's on its second block, had about five top end overhauls and and a couple of bottom end rebuilds - there's very little if any, of the original engine left - to me that is not quality engineering:
https://www.pistonheads.com/news/ph-...h-heroes/36026
I know about this Murciélago, but I would not want to drive one of these that much as it would ruin the sense of occasion, which is what these cars are all about. Even then, do you honestly believe you will drive your 944 turbo even just 100,000 miles once it is done? I bet you won't.
100,000 miles in a Italian V12 will be fare more exciting than even a million mile in a cringing Mercedes, and this is the point.
05-30-2023, 04:56 AM
#204
Nick, to me it's a tuned 944 turbo - not a fast car by modern standards, but hopefully respectably quick, durable & reliable for an old four cylinder Porsche.
If you look at a modern car like the M2 Comp with the S55 - a 24 valve, twin-turbo, six cylinder - its potential is enormous - with E85 the Pure Turbo's Stage 2+ kit it is approaching 800 whp.
Given that my 952 is so easily out-classed by quite modest modern machinery - to me it's not worth spending any more money on it - I just want it to be reliable for extended track sessions (up to 45 minutes) at the faster European tracks.
As I've said before, a 2200+ kg luxo barge with five people on board & their holiday luggage (Mercedes S65 / BMW 760 Li / Bentley Flying Spur Speed / Rolls Royce Black Badge Ghost) will take apart my 952 in a straight line, so it's not worth getting too upset about its performance or lack thereof.
If you look at a modern car like the M2 Comp with the S55 - a 24 valve, twin-turbo, six cylinder - its potential is enormous - with E85 the Pure Turbo's Stage 2+ kit it is approaching 800 whp.
Given that my 952 is so easily out-classed by quite modest modern machinery - to me it's not worth spending any more money on it - I just want it to be reliable for extended track sessions (up to 45 minutes) at the faster European tracks.
As I've said before, a 2200+ kg luxo barge with five people on board & their holiday luggage (Mercedes S65 / BMW 760 Li / Bentley Flying Spur Speed / Rolls Royce Black Badge Ghost) will take apart my 952 in a straight line, so it's not worth getting too upset about its performance or lack thereof.
Last edited by Thom; 05-30-2023 at 05:15 AM.
05-30-2023, 05:43 AM
#205
Rennlist Member
Thread Starter
Thom, I take your point about the twin cam head, but I think the 951 / 952 will always suffer from the fact that is simply not a six-cylinder car.
What I mean by that is a "six" just is & definitely sounds smoother, more expensive, a premium vehicle - that is where modern equivalents of the 951, like the M2 Comp, really shine. That "six" is just class whereas a "four" has the crude sound of an "economy" car.
Are custom cams available for the 16 valve head? What intake manifold are you using?
For me the 3 litre was never attractive with its higher piston speeds, poorer rod length to stroke ratio resulting in higher cylinder sidewall loads, the increased crank flex and the increase in negative harmonics - I get that there's a torque increase - but a 3 litre four cylinder - really? A 3 litre should be a six cylinder- indeed the first road going Ferrari, the 166 Inter was a 2 litre V12.
Reciprocating masses should be light & the forces spread over has many cylinders as possible which also has the benefit of increased valve area.
My thinking is I suppose I've put my 952 in a box - it was a car Porsche cheaped out on & I've spent a financially imprudent sum fixing its weaknesses when really that money would have been better spent on a newer, better car built to a higher standard in the first place. You can't make a silk purse out of a sour's ear. How many on these boards could have bought a second hand GT3 for the money they've spent on their 951/952 - and which will lose you less money?
What I mean by that is a "six" just is & definitely sounds smoother, more expensive, a premium vehicle - that is where modern equivalents of the 951, like the M2 Comp, really shine. That "six" is just class whereas a "four" has the crude sound of an "economy" car.
Are custom cams available for the 16 valve head? What intake manifold are you using?
For me the 3 litre was never attractive with its higher piston speeds, poorer rod length to stroke ratio resulting in higher cylinder sidewall loads, the increased crank flex and the increase in negative harmonics - I get that there's a torque increase - but a 3 litre four cylinder - really? A 3 litre should be a six cylinder- indeed the first road going Ferrari, the 166 Inter was a 2 litre V12.
Reciprocating masses should be light & the forces spread over has many cylinders as possible which also has the benefit of increased valve area.
My thinking is I suppose I've put my 952 in a box - it was a car Porsche cheaped out on & I've spent a financially imprudent sum fixing its weaknesses when really that money would have been better spent on a newer, better car built to a higher standard in the first place. You can't make a silk purse out of a sour's ear. How many on these boards could have bought a second hand GT3 for the money they've spent on their 951/952 - and which will lose you less money?
05-30-2023, 05:52 AM
#206
Thom, I take your point about the twin cam head, but I think the 951 / 952 will always suffer from the fact that is simply not a six-cylinder car.
What I mean by that is a "six" just is & definitely sounds smoother, more expensive, a premium vehicle - that is where modern equivalents of the 951, like the M2 Comp, really shine. That "six" is just class whereas a "four" has the crude sound of an "economy" car.
Are custom cams available for the 16 valve head? What intake manifold are you using?
For me the 3 litre was never attractive with its higher piston speeds, poorer rod length to stroke ratio resulting in higher cylinder sidewall loads, the increased crank flex and the increase in negative harmonics - I get that there's a torque increase - but a 3 litre four cylinder - really? A 3 litre should be a six cylinder- indeed the first road going Ferrari, the 166 Inter was a 2 litre V12.
Reciprocating masses should be light & the forces spread over has many cylinders as possible which also has the benefit of increased valve area.
My thinking is I suppose I've put my 952 in a box - it was a car Porsche cheaped out on & I've spent a financially imprudent sum fixing its weaknesses when really that money would have been better spent on a newer, better car built to a higher standard in the first place. You can't make a silk purse out of a sour's ear. How many on these boards could have bought a second hand GT3 for the money they've spent on their 951/952 - and which will lose you less money?
What I mean by that is a "six" just is & definitely sounds smoother, more expensive, a premium vehicle - that is where modern equivalents of the 951, like the M2 Comp, really shine. That "six" is just class whereas a "four" has the crude sound of an "economy" car.
Are custom cams available for the 16 valve head? What intake manifold are you using?
For me the 3 litre was never attractive with its higher piston speeds, poorer rod length to stroke ratio resulting in higher cylinder sidewall loads, the increased crank flex and the increase in negative harmonics - I get that there's a torque increase - but a 3 litre four cylinder - really? A 3 litre should be a six cylinder- indeed the first road going Ferrari, the 166 Inter was a 2 litre V12.
Reciprocating masses should be light & the forces spread over has many cylinders as possible which also has the benefit of increased valve area.
My thinking is I suppose I've put my 952 in a box - it was a car Porsche cheaped out on & I've spent a financially imprudent sum fixing its weaknesses when really that money would have been better spent on a newer, better car built to a higher standard in the first place. You can't make a silk purse out of a sour's ear. How many on these boards could have bought a second hand GT3 for the money they've spent on their 951/952 - and which will lose you less money?
Our M44 engines will never make grunt under 4000 rpm and very often die before 7000.
and they don't sound very cool either.
I wish the 07k swap was available when my engine went **** 6 years ago, but now it's happening, just after i spent 15k on the M44 engine.
I even had a 3.1L 16v in parts, before i sold that.
Knowing I'll never be happy with the performance or sound.
I get that people want the purity for nice cars, but racing or Trackdays on a medium + level the M44s will break.
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Thom (05-30-2023)
05-30-2023, 06:01 AM
#208
Rennlist Member
Thread Starter
These boards are quite rightly supported by 951 / 952 enthusiasts who have lavished much time, money, energy & love on their vehicles - and who am I to rain on their parade.
I'm just saying that for me personally - I've gone as far as I wish to go with my 952 and if it's disappointing - then that's entirely my fault & it's not a mistake I'll repeat.
I'm just saying that for me personally - I've gone as far as I wish to go with my 952 and if it's disappointing - then that's entirely my fault & it's not a mistake I'll repeat.
05-30-2023, 06:13 AM
#209
Rennlist Member
Thread Starter
On the originality continuum I'm generally somewhere around the mid-point. I like a well tuned version of the original car - even if that means accepting its limitations.
Some people are after the biggest bang for their buck, hence LS conversions - a truly great engine in a great platform - I can totally see the logic.
For others, the "purists", it's only original once & any deviation from totally stock is a travesty.
Ealoken, I really look forward to reading about your 07k swap - I think that motor will suit the character of the 951 really well - a turbocharged, higher revving, twin cam, European engine.
Great as the LS is - it always sounds a little incongruous to me to hear a US V8 burble from the tail pipes of a 951, when a fine twin cam turbo "six" or the gruff warble of the Audi turbo five would be more at home.
Some people are after the biggest bang for their buck, hence LS conversions - a truly great engine in a great platform - I can totally see the logic.
For others, the "purists", it's only original once & any deviation from totally stock is a travesty.
Ealoken, I really look forward to reading about your 07k swap - I think that motor will suit the character of the 951 really well - a turbocharged, higher revving, twin cam, European engine.
Great as the LS is - it always sounds a little incongruous to me to hear a US V8 burble from the tail pipes of a 951, when a fine twin cam turbo "six" or the gruff warble of the Audi turbo five would be more at home.
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ealoken (05-30-2023)
05-30-2023, 06:17 AM
#210
Please don't take this in a bad way but your technical observations are far too general and may need to be backed with real world experience. We can definitely have low down grunt out of a 3L engine, like 400 lbs.ft at 3000 rpm. That is more than enough. This may not happen with a 16V engine but the unreal top end urge compensates more than enough and you will be happy that the engine behaves at lower rpm whilst it could throw you out of the road in the blink of an eye when you go full load at higher rpm, even when you are pointing both wheels straight with fresh rear tyres.
Crank flex with a 25 kg crank, really? Who else has racked up 70,000 miles with their 3L 8V, many of these on derestricted Autobahn and regularly seeing high EGT with no breakage? Like any other engines they will last if they are respected and taken care of.
Stock 16V cams are good enough, and my welder can supply 16V intakes in any configuration needed, though it comes at a price as this a specialist job.
From a financial point of view it makes sense to me to have spent all that I have spent as I have a car with supercar performance yet looks still like your run-off-the-mill old 944 and requires so much concentration when flooring the throttle that I have no brain cell left to care about the sound, which in fact really isn't that bad at all with the 16V head and a proper muffler, and it still retains the usability of a VW Golf. Why would I want to waste time with a 911 which are cars I have never really cared about, and make me look just like another guy with some dull GT3? To me they look wrong, they sound wrong and they drive wrong.
I have never understood the desire to track our cars, they are too heavy and too costly on consumables for such a use, and some high end spenders on here have shown they can break regardless how much is being spent.
As for sticking to originality, I can't see the point considering the high production numbers. Genuinely good cars will become ever rarer, but ok cars will never be rare.
Crank flex with a 25 kg crank, really? Who else has racked up 70,000 miles with their 3L 8V, many of these on derestricted Autobahn and regularly seeing high EGT with no breakage? Like any other engines they will last if they are respected and taken care of.
Stock 16V cams are good enough, and my welder can supply 16V intakes in any configuration needed, though it comes at a price as this a specialist job.
From a financial point of view it makes sense to me to have spent all that I have spent as I have a car with supercar performance yet looks still like your run-off-the-mill old 944 and requires so much concentration when flooring the throttle that I have no brain cell left to care about the sound, which in fact really isn't that bad at all with the 16V head and a proper muffler, and it still retains the usability of a VW Golf. Why would I want to waste time with a 911 which are cars I have never really cared about, and make me look just like another guy with some dull GT3? To me they look wrong, they sound wrong and they drive wrong.
I have never understood the desire to track our cars, they are too heavy and too costly on consumables for such a use, and some high end spenders on here have shown they can break regardless how much is being spent.
As for sticking to originality, I can't see the point considering the high production numbers. Genuinely good cars will become ever rarer, but ok cars will never be rare.
Last edited by Thom; 05-30-2023 at 06:37 AM.