944 Turbo S Engine Rebuild Thread

[blade7]

I've had a new set of Carrillo rods, and a 2.7 block in my garage for years. 30 year old cast rods in my 100k miles engine too. I don't tend to rev it over 6k very often these days though.

 

[PSH]

I've had a new set of Carrillo rods, and a 2.7 block in my garage for years. 30 year old cast rods in my 100k miles engine too. I don't tend to rev it over 6k very often these days though.

I've unintentionally hit 7134rpm at 92% throttle, according to 'gearcalc' that's over 196mph with the 951's final gear ratio...

 

[Eldavo]

I’ve put brand new forged rods in and they came with ARP2000 bolts.


Went for 85 ft/lbs torque value in the end in 3 stages with the correct lube as this lined up with what a lot of other engine builders in the states have used on this stud and gasket combo and it worked out to be pretty much bang on with torque value + 90 degrees + 90 degrees in the end anyway.

 

[Eldavo]

Wish I had one of these!

 

[PSH]

I used my son's...a very clever piece of kit..

Pete

 

[Eldavo]

Plenty of progress made today, lots of wiring sorted and new vacuum lines fitted too. Cam paid for today and being finished and sent tomorrow. Should be buttoned your by the end of the week!

 

[blade7]

I've unintentionally hit 7134rpm at 92% throttle, according to 'gearcalc' that's over 196mph with the 951's final gear ratio...

According to the diagram I've got, you're over estimating by at least 10 mph there fella. And that's not taking into account tacho error either. For comparison, my old BMW S1000RR would easily do a genuine 190mph plus. I stopped looking down at the speedo before seeing that though.

 

[PSH]

No chart involved...gear calc is a recognised online program which caculates your speed from the info entered, all info was entered correctly. Tacho has no say in this as my engines datalog recorded exactly what the actual RPM was. My monitor was set to record RPM, throttle and boost. That's how I know it was 92% throttle...IIRC the throttle read 92.1% and the boost just over 1.4 BAR

 

[Eldavo]

I thought that Gearcalc didn’t account for air resistance. I don’t really see any 944T hitting much more than 180mph without big power and a different gearbox. Wasn’t it supposedly 156mph new?

 

[blade7]

I thought that Gearcalc didn’t account for air resistance. I don’t really see any 944T hitting much more than 180mph without big power and a different gearbox. Wasn’t it supposedly 156mph new?

Think it was 152mph in tests I've read, which made it surprising Porsche managed to add another 10mph with just another 30bhp on the 250bhp cars. Though I think factory press cars were often enhanced. I'm not sure if Pete actually believes some of the things he posts either [].

 

[PSH]

I thought that Gearcalc didn’t account for air resistance. I don’t really see any 944T hitting much more than 180mph without big power and a different gearbox. Wasn’t it supposedly 156mph new?

Think it was 152mph in tests I've read, which made it surprising Porsche managed to add another 10mph with just another 30bhp on the 250bhp cars. Though I think factory press cars were often enhanced. I'm not sure if Pete actually believes some of the things he posts either [].

Haha

No, it doesn't count for wind which, yes would have an effect although as I keep telling my son, nowhere near as much as on his Cossie... There is enough power to achieve such a speed, not that I will ever try it, the tyres are 'Y' rated so can safely do 186mph. There are 951's out there recorded at over 200mph, just as there are Cossie's, it's just not my thing.
Yes, the official top speed for an '86' was 152, although Porsche is well known for underestimating their car's performance, various road tests of the day showed higher speeds, some recorded at 159 mph, none were lower. That's with 220bhp and as has been pointed out, the 250bhp took this up to 162 mph with only very slightly more boost. So a 951 with over 400bhp and at more than double the original boost, plus being very light in modern terms, well it's not rocket science to realise that it's going to be much faster, very much so.
I will never know just how fast it is, when I fall off my perch perhaps one of my boys will take it for a timed run, I'll have to watch from the clouds...

Pete

 

[924Srr27l]

Haha

That's with 220bhp and as has been pointed out, the 250bhp took this up to 162 mph with only very slightly more boost. So a 951 with over 400bhp and at more than double the original boost, plus being very light in modern terms, well it's not rocket science to realise that it's going to be much faster, very much so.

Pete

But lighter car's are slower than heavier cars at reaching a higher top speed (Even with like for like power to weight ratio's)

EG a 1500kg car with 200 bhp per tone will achieve a higher top speed
than one that's also 200bhp per ton but only weighs 1000kg

Inertia increases with increasing mass, and a car's inertia is one of the forces pushing the car forward, increasing inertia will increase the top speed.
Since increasing mass increases inertia, increasing mass will increase top speed.

R

 

[vitesse]

Pull the other one,Roger-momentum doesn't propel a vehicle-but helps a vehicle sustain its speed all things being equal.
If your theory were to be true ,how come Colin Chapman didn't make his designs as heavy as possible.
Why are Single seater racing cars so light -why not race trucks ???????

 

[924Srr27l]

Pull the other one,Roger-momentum doesn't propel a vehicle-but helps a vehicle sustain its speed all things being equal.
If your theory were to be true ,how come Colin Chapman didn't make his designs as heavy as possible.
Why are Single seater racing cars so light -why not race trucks ???????

Highest Top speed, if this is the only objective & discussion? then a higher Mass wins over a lighter one due to the air resistance
A lighter vehicle is very advantageous for acceleration and handling (Great for circuit Racing)

More weight and inertia like a flywheel which a heavier one sustains more Momentum than a lighter one..

Another example in Downhill push bike Racing:
Heavier bikes and riders are faster downhill because they experience a higher force from gravity, but have relatively the same wind resistance as a lighter rider and bike. ... The only variable is mass, so the heavier mass will have greater force to overcome air resistance.

Galileo discovered that objects that have more mass, fall at a faster rate than less dense objects, due to this air resistance.

R,

 

[blade7]

Haha

No, it doesn't count for wind which, yes would have an effect although as I keep telling my son, nowhere near as much as on his Cossie... There is enough power to achieve such a speed, not that I will ever try it, the tyres are 'Y' rated so can safely do 186mph. There are 951's out there recorded at over 200mph, just as there are Cossie's, it's just not my thing.

Pete

I've read about and sensed myself a feeling of lightness in the steering when going flat out in a 944 turbo. And IMO the car needs a splitter to add some extra front end downforce. Adding an extra 20+mph would only make this more noticeable surely?

 

[PSH]

funny, as I've never experienced any sort of lift at high speed and I have driven well past 170mph (btw, that was with only 282 bhp) I've just been reading a great article from a guy who owns both an '86' 951 and a 930, he made it very clear which is the better car. In fact, he said the '86' 951 is the best car that Porsche has ever built, he should know, having owned over 40 Porsche's. He has two 951's, one is modified for the track, more power than mine but on banked circuits, he has seen it log 200mph.

As I have said many times, they are very special cars...in all forms

Pete

 

[PSH]

Oh...forgot to add that Roger is correct on mass but for our scenario it's unlikely to make a noticeable difference....

 

[924Srr27l]

Oh...forgot to add that Roger is correct on mass but for our scenario it's unlikely to make a noticeable difference....

Our scenario ? you mean as your car's not light.
If it were 400kg lighter it would have a slower top speed...(It would corner faster and accelerate quicker but this scenario / question is how fast can a 44 turbo go stock & Modded)

R

 

[PSH]

I mean the differences involved in this discussion will be minuscule if anything at all? The higher maas may mean more speed (on paper), but there are other factors which may not only balance this mass but also make the higher mass go slower... Dropping a weight of a higher mass does not come into this, we are talking 'cars' and cars are affected by other things. Rolling resistance for one will be higher in a heavier car, there is a drag effect o think off too..... My maths isn't up to this stuff, mind you, I bet my son could go through this with ease (his thesis was very much in this area) and give you all the facts given a certain weight/mass, speed etc. IMHO, common sense to me says, lighter is better when talking about a car.....

 

[924Srr27l]

I mean the differences involved in this discussion will be minuscule if anything at all? The higher maas may mean more speed (on paper), but there are other factors which may not only balance this mass but also make the higher mass go slower... Dropping a weight of a higher mass does not come into this, we are talking 'cars' and cars are affected by other things. Rolling resistance for one will be higher in a heavier car, there is a drag effect o think off too..... My maths isn't up to this stuff, mind you, I bet my son could go through this with ease (his thesis was very much in this area) and give you all the facts given a certain weight/mass, speed etc. IMHO, common sense to me says, lighter is better when talking about a car.....

YEs do that ....ask your Son to clarify the physics etc...(2 cars, both same power to weight / shape / same wheels etc...but one of them is 2 ton the other 1 ton )
sure I'm all in for lightweight cars, So far I've taken a total of 300kg out mine....

R