944 turbocharger options

[TTM]

ORIGINAL: PSH
keep the 8 valve head Pete.. I hate 16 valves... no low down torque and far too much throttle needed to get going in comparison... ok for the race track when the engine is screaming it's nuts off 90% of the time but who wants that for a road car? not me...

Not sure I agree with this. As far as I have observed the 16V head is superior to the 8V head by all accounts.

The inlet valve area of a 16V head is higher than an 8V head with a 51mm valve, which is very large, in fact so large that the outer edge of the valve may move worryingly close to the cylinder wall, which could possibly alter a flow figure that was initially excellent on a flow bench.
Friend of mine uses 52mm valves in a 102mm bore engine, and his heads flow a staggering 300cfm each, but that is on a pushrod V8 engine where the plane of the sliding inlet valve is not parallel with the plane of the cylinder, and as his inlet valve slides open, it moves towards the center of the cylinder, giving enough room to the air to flow more or less evenly around the valve, whereas the plane of the inlet valve stays parallel to the plane of the cylinder on our engines, if you see what I mean. When increasing valve area isn't enough to improve flow, then we have a problem that only ace (read €xp€nsiv€) machine shops with lots of experience working on cylinder heads may solve.

Only reason most (me included) build 8V 3L engines is that most of the original hardware (inlet and outlet manifolds, etc) is reusable with little to zero modifications.
In my case, I just cannot justify building a 16V engine because I believe the difference in performance my not be big enough to justify the additional expense. However, if I were to do it again I would build a 16V engine from the start.
The irony is that the usual 944T enthusiast may initially find easier or more natural to build an 8V, also because Porsche did it themselves, but may find out after it's done there is actually little additional effort needed to build a 16V engine that will perform (and sound []) better.

 

[simkin911]

I always find these threads interesting, informative and sometimes quite imaginative too. Easy to forget that these cars can provide fabulous performance on a good stock engine of circa 300bhp with only the typical external modifications. My last turbo had 300bhp and was really responsive but even at this level it was never easy to exploit this in normal driving conditions (overtaking with confidence was valuable though).

 

[Eldavo]

I agree!

Threads like these invariably end up with the car off the road for months or years at a time.

I'd rather have 12 months of 300bhp than 1 month of 400bhp.

 

[TTM]

So far I have had 5 years and 30k miles of 400hp/400ft.lbs ... and still counting []

 

[Ex Skyline]

ORIGINAL: MarkK

Please have a dyno day when these cars are built?Dont forget it's got to be a dyno dynamics dyno....! (Rollers of truth.....)
[]

Yeah. Not that geezer with the workshop at Thruxton Circuit []! I don't think anyone got above 200 brake on his dodgy rollers [8|]
Unless, of course, everybody was deluded in their high expectations [][]!!

 

[Ex Skyline]

ORIGINAL: TTM

So far I have had 5 years and 30k miles of 400hp/400ft.lbs ... and still counting []

Who built your engine mate? Do you "give it the beans" regularly or, potter sedately round the country lanes so as not to give
granny the hiccups when your taking her home after Sunday lunch? [][]. Seriously, five years is a long time for a hot engine to
survive if you give it a serious pasting on a regular basis.

 

[aporschefan]

ORIGINAL: TTM

So far I have had 5 years and 30k miles of 400hp/400ft.lbs ... and still counting []

Which turbo are you using? (Is there a thread for your project/build?)

 

[tref]

ORIGINAL: Ex Skyline

ORIGINAL: MarkK

Please have a dyno day when these cars are built?Dont forget it's got to be a dyno dynamics dyno....! (Rollers of truth.....)
[]

Yeah. Not that geezer with the workshop at Thruxton Circuit []! I don't think anyone got above 200 brake on his dodgy rollers [8|]
Unless, of course, everybody was deluded in their high expectations [][]!!

...which was selected because it was Dyno Dynamics rollers. I believe he can make the rollers read 300bhp if that is what we want to see[] Mine was reading better than I expected (didn't even slip him an extra tenner;-))

 

[PSH]

[/quote]

...which was selected because it was Dyno Dynamics rollers. I believe he can make the rollers read 300bhp if that is what we want to see[] Mine was reading better than I expected (didn't even slip him an extra tenner;-))
[/quote]


which is why MarkK rightly states only use Dyno Dynamics rollers 'rollers of truth' and in shoot out mode with the proper atmospheric pressures set. This is not the norm for some other Marque shoot outs with crazy figures shown....when my car was first set by Wayne on his rollers I was a little sceptical of the good power output not knowing the make... my fears were laid to rest a few weeks later when we did the shoot out at Silverstone on a Dyno Dynamics roller giving me the same output as Wayne's, within 1/2 bhp, so not all tuners cheat the results. An example of giving false readings was when we all went to the Dyno Dynamics session down at Bournemouth airport, can't remember the name... my car was performing badly... even bought some vac tube of them and renewed everything thinking that may have been the problem. Still no good, struggling to get over 300bhp, the tuner then changed the settings to what they normally use,, car then made over 330bhp.. still way down but he could have tweaked the rollers more... my point is don't trust the dyno plot unless under strict conditions with the barometer set correctly. Later I found the reason for my car's poor performance, a number of reasons in fact but it won't happen again... next dyno run she will be on top form...

Pete
Oh and I still say for turbo engines and for the 944T in particular 8 valves are best... just my preference I don't like how 16 valve cars respond to the throttle, less stable, need more revs low down to get the torque and we all know how the 944T likes to bog down on pull off...

 

[George Elliott]

quote:

ORIGINAL: TTM

So far I have had 5 years and 30k miles of 400hp/400ft.lbs ... and still counting



Who built your engine mate? Do you "give it the beans" regularly or, potter sedately round the country lanes so as not to give
granny the hiccups when your taking her home after Sunday lunch? . Seriously, five years is a long time for a hot engine to
survive if you give it a serious pasting on a regular basis.

Pete, Jabriel,
I dont know TTM, but I think you may find we potter about more than he does due to our speed limited roads and his use of the French autoroutes and German autobahns. So be careful - he may ask for you recent highest speed and distance [8|]

What I do know from his posts is that he makes many good suggestions (see the inclined valves described above as an example).

I am interested in Jon's comments on 8 and 16. There is a strong 8v following here, the 968 turbo went that way, 8 valves are nicer in that they will pull low down as PSH says, and the Parts a 99% bolt on, and if TTM has had such good reliability, it proves 8 is a good route. Then again the 996TT is 4valve / cylinder.

I think, if Martin comes up with a 16v direct injection, vario-ram cylinder head package as one of his next projects, I will try that []
400hp and 40mpg

George
944t

 

[Ex Skyline]

George, I wasn't questioning TTM's integrity mate, purely interested to know who built his engine etc is all []. I'm looking for a
totally "Bullet Proof" engine for my own ends. One that can stand the test of time and, loads of track days to boot without, blowing
up []. A readily available, 400 brake, 8 valve is what I am looking for and, is just what Jon' has promised me [8D]!!

 

[TTM]

Sorry for replying so late, I was busy giving hell to my engine on the nearest Autobahn. Was the 3rd time this month but I did not get the chance to go that fast, there was too much traffic, couldn't hold faster than 140 mph for a minute or two. Now hopefully the Schmidts will win on Sunday evening and we will have a great evening.

The guys who built my engine were a friend of mine and me. It was the third 951 engine we built, but the first 3L 8V. The next one coming is a 3L 16V for my friend but life has kept getting in the way so no idea if it will ever get completed. I don't consider mine really bullet proof yet as, even if I never broke anything yet, I am yet to install a larger oil cooler, as even with 2 plugged in series oil is still getting too hot for my liking. Building a reliable 951 engine is, after all the other obvious aspects have been adressed, mostly about heat management, I think.

ORIGINAL: aporschefan
Which turbo are you using? (Is there a thread for your project/build?)

Check the old thread named "Engine build progress". It ran for quite some time but I can't be bothered updating it anymore, think we all got bored with it.

 

[PSH]

ORIGINAL: Ex Skyline

George, I wasn't questioning TTM's integrity mate, purely interested to know who built his engine etc is all []. I'm looking for a
totally "Bullet Proof" engine for my own ends. One that can stand the test of time and, loads of track days to boot without, blowing
up []. A readily available, 400 brake, 8 valve is what I am looking for and, is just what Jon' has promised me [8D]!!

hi Pete

A few things to bear in mind if you want an engine at 400 brake and to still be bullet proof, is there is such a thing? Can't remember which year your car is but if after 86 you'll need to change the rods, early cars had forged rods which can take anything you've likely to throw at them. Later cars have cast which have proven to let go over 350 bhp when pushed hard, 944T's have a weak spot on number 2 con-rod bearing so make sure you have new small ends fitted, something that some people forget to do. Upgrade all studs, head, main and most importantly rod studs. I installed raceware in mine but there are alternatives out there, not sure if any cheaper though, IIRC my stud sets cost me well over £1k, may have been as much as £1.5K. The Porsche rod bolts are rated for about 180'000 psi, raceware are 210,000 psi. The standard rod bolts have been known to stretch under extreme conditions, I call 400 bhp+ extreme, hence why i did mine. If mild to moderate upgrades are planned then the standard block will be ok, my own at 368 bhp was fine for many years but now that I'm going further things have been changed to ensure that the engine can cope with what's asked of it, not that I'll drive it hard anymore anyway.. getting too old for the boy racer stuff....

Pete

 

[Ex Skyline]

TTM, totally agree with you about heat management mate, a very good point indeed! I too, hope the Hun win on Sunday []!
I have quite a few German friends and, would love to watch the World Cup final with them in Hamburg. What a fantastic
weekend that would be [8D]. Never mind, Pete, thank you for all your very interesting comments. If you don't mind, I may well
give you a bell for a chat and, some advice when I get stuck into this project in a few weeks time [].

 

[PSH]

You've very welcome Pete.. any time...

Pete

 

[George Elliott]

A readily available, 400 brake, 8 valve is what I am looking for and, is just what Jon' has promised me !!

Look forward to hearing about this, Jon will make it happen. will be a great car.[]

George
944t

 

[John Sims]

ORIGINAL: George Elliott

Look forward to hearing about this, Jon will make it happen....

George
944t

Eventually. [8|]

 

[TTM]

Woohoo! []

 

[333pg333]

I pretty much agree with TTM / Thom and given the chance, would build up a 16v motor. I think those that say the 16v turbos are breathless in lower rpm compared to 8v just haven't been in one. It's more the long runner intakes of the 8v that give them the early to mid range tq as most 16v turbos have aftermarket shorter runner intakes. My friend's 951 with a turbo'd S2 motor is very quick and he hasn't done anything stupidly custom on that motor. I would also possibly go down a little in capacity (for a race motor) if I was building another motor but for a street car, going up to 2.8 or 3+ltrs is a worthwhile move and not really expensive in the long run. Besides, changing the pistons and rods from 25+ year old stock parts is advisable anyway. So factor in a crank and you're there.
I think we squeezed about 330whp on a Dyno Dynamics dyno with my stock 2.5L motor with a GT30 and bigger cam. With some headwork it would have been a little better too.

 

[Ex Skyline]

ORIGINAL: John Sims

ORIGINAL: George Elliott

Look forward to hearing about this, Jon will make it happen....

George
944t

Eventually. [8|]

Now, now John, don't be a B1tch [8|].....[]. A very droll B1tch never the less []!!