I wasn't trying to imply it was some type of flaw, just a characteristic and I was just responding to the OP's comments about the top end and agreeing that getting the cam timing right is important as too much advance will only emphasise the drop off in torque at higher rpm. I appreciate there is a lot of 951 love around here but it certainly wasn't meant to be a negative comment more a fact of life. The torquey mid range is one of the things that make the cars so quick in the real world. On a 3.0 8v this characteristic is only further exaggerated and you have to work harder to dial it out so if I had my time again I would bite the bullet and go 16v. I think the 2.5 is probably the sweet spot for the 8v head.
944 Turbo S Engine Rebuild Thread
- Thread starter Eldavo
- Start date
924Srr27l
New member
[/quote]
TTM said:924Srr27l said:
I'll leave this expert question to the appreciation of others who are hopefully at least as clever as you []
Oh sorry ! i thought you were the expert giving out all the advice inc the RPM issue which you say is incorrect / delayed etc... ?
I'll wait for the experts, obviously nobody from here ! so my question will no doubt be left in it's wake! ...again
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PSH
PCGB Member
An interesting discussion on rev counter accuracy, does anyone actually look at their rev counter while driving hard?...
I haven't heard of this before so can't add to the subject or indeed answer with any real-world experience as to whether it's fact. My question would be even if the rev counter is giving a different reading what is the engine reading, surely not the rev counter? If looking at the Porsche handbook it clearly shows the full powerband curve and the revs it reaches so I would suggest that this is accurate, not hearsay about the Bosch system. I can give some input into the actual revs of my own ( ok modified) car, as some of you will be aware my red line is set at 7200 and the EBC data log would confirm that this rpm is reached as it has recorded 7254 on one occasion and slightly less on another. My own head is a stage 2 polished item which I'm sure helps with the breathing but the head alone is not enough, it needs the other components to match and back it up . I have never been a fan of bigger capacity on these engines and why I stuck to 2.5, IIRC this was stated early in my build thread with my reasons.
The 2.5 with a decent turbo is a great car, tune it up properly with matching components and it's superb, getting the parts balanced is the important part and I'm not talking of their weight...
Pete
I haven't heard of this before so can't add to the subject or indeed answer with any real-world experience as to whether it's fact. My question would be even if the rev counter is giving a different reading what is the engine reading, surely not the rev counter? If looking at the Porsche handbook it clearly shows the full powerband curve and the revs it reaches so I would suggest that this is accurate, not hearsay about the Bosch system. I can give some input into the actual revs of my own ( ok modified) car, as some of you will be aware my red line is set at 7200 and the EBC data log would confirm that this rpm is reached as it has recorded 7254 on one occasion and slightly less on another. My own head is a stage 2 polished item which I'm sure helps with the breathing but the head alone is not enough, it needs the other components to match and back it up . I have never been a fan of bigger capacity on these engines and why I stuck to 2.5, IIRC this was stated early in my build thread with my reasons.
The 2.5 with a decent turbo is a great car, tune it up properly with matching components and it's superb, getting the parts balanced is the important part and I'm not talking of their weight...
Pete
Re the rev counter Vs actual engine speed. I can answer that.
The motronic in my turbo literally just supplies the gauges and the KLR knock output.
Yes the revs on the gauge overread compared to actual engine speed. I just double checked, in the same way the other gauges are fairly inaccurate. I'd put it down to old age previously, not a 'feature'.
As to the rev limit, I'd have to Datalog both but life is far to short but I'd be prepared to bet it is where it is regardless of what the gauge shows.
The motronic in my turbo literally just supplies the gauges and the KLR knock output.
Yes the revs on the gauge overread compared to actual engine speed. I just double checked, in the same way the other gauges are fairly inaccurate. I'd put it down to old age previously, not a 'feature'.
As to the rev limit, I'd have to Datalog both but life is far to short but I'd be prepared to bet it is where it is regardless of what the gauge shows.
blade7
Well-known member
Most of what I've read suggests the bigger ports and inlet valves on a standard 2.7 head outflow a 2.5 head, up until a lot of money has gone into a 2.5 head. The 2.7 head doesn't make a lot of sense for the naturally aspirated engine it came on. The 2.7 head and block were designed for an updated turbo engine that never happened. Fitting a 16v head on a roadgoing 944 turbo is over egging the pudding IMO. 400 bhp is plenty for the rear suspension setup to handle. Buy a 996/7 turbo if you want to put the power down to the road, and go faster.
TTM
Well-known member
I am not sure it is even about bare figures, but more about how it puts the power down. Some will prefer to spin the rear tyres as early as possible and won't mind changing gears earlier, whilst others will prefer a freeer-revving engine which makes the car flies and a little more challenging, involving, and feels more "natural" to drive fast, which is more what I would personally expect from anything pretending to be a "sports car"... which begs the question - is the 944 turbo even supposed to be a "sports car"? Out of the box I think we will all agree that they clearly drive like motorway cruisers more than anything else.
PS : I drove a 600hp 996 turbo a few years ago and to this day it remains the most boring car I have ever driven.
PS : I drove a 600hp 996 turbo a few years ago and to this day it remains the most boring car I have ever driven.
924Srr27l
New member
LINDSEY RACING - Your Porsche Performance Parts Center: LINDSEY HEADS
www.lindseyracing.com/LR/Parts/LRHEADS.html
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www.lindseyracing.com/LR/Parts/LRHEADS.html
R
924Srr27l
New member
TTM said:
Yes I can quite agree, same for me with a Audi 600bhp RS6 V10 but why is this?
It's all about Feel, a combination of motion and touch.
Why some cars with low power figures, lighter and good handling chassis far exceed many others with larger figures and badges
because they are more nimble, you can get on the throttle sooner and it's more responsive etc..
Watch this and you decide if you'd rather be in a light small capacity / power car or a Heavy larger capacity / power
Both look like fun. but each one is totally different to operate than the other this is often the same case with road cars
also why most Hypercars use normally aspirated engines and not forced induction because they are more fun.
St Mary's Trophy pt2 2021 | Highlights | Goodwood Revival | '50s touring cars in hair-raising race - YouTube
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TTM
Well-known member
blade7 said:
Well, I know that you have a personal tendency to disagree with anyone possible just for the sake of it, but in case your post isn't tongue in cheek for once then I can only encourage you to try some other sports cars with naturally-aspirated engines, as you might then realise that a 944 turbo in standard tune, with its flywheel heavy to the point where there is barely any engine braking and its general poor dynamics, really cannot be considered a "sports" engine, even by mid-1980s standards. Quick yes, but not involving until it is at least chipped.
PSH
PCGB Member
Wow...well it's lucky for Porsche then that the world's auto journalists disagree with you TTM and I'm not just referring to those when the car was new. Even today's most famous journalists have the 951 in their top ten all time best cars (Tiff has it higher) and lets just look at that for a second, these are experts who have driven every (yes every) high performance and everything else model car built ..I've never heard such rubbish...
Pete
Pete
924Srr27l
New member
TTM said:
Yes I agree on all, but as ever it's always subjective to different people likes and dislikes, their driving abilities and budgets etc...
There's so many variables to consider when trying to convince car lovers on something that you've found and like, it's most often a losing game!
I see this every day in my Automotive profession, people are so enthusiastic about how fast and good their car is , when if you've been lucky to venture to much higher
better vehicles then it's very odd and difficult to get excited about something which you personally don;t find great at all!
The Turbo V N/A debate will never die, this thread however is about the rebuild of a Turbo engine so I guess it's not the place to discuss this!
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924Srr27l
New member
PSH said:
Tiff is nearly age 70 Pete! and the Transaxle design coming up 50 years so I'm certain that if we go back to the 1980;s and 90's the accolades are quite rightly valid, but here in 2021
a lot has changed where a modest hatch is now far superior in performance to an old transaxle classic...
Modified is a different story, as anyone can modify a 50 year design car and give it a higher power to weight, although you're still up against the flexible chassis and 70's handling..
I mean the Transaxles have always been the underdog, as it was a joint VW venture which collapsed and as we know Porsche produced it with their badge and a very percentage VW/Audi
It surprised the world as the parts were from decades old! 1950's Daimler derived engine, 1940's Beetle suspension etc...but the layout worked very well and they developed it as we know over nearly 2 years from a 95bhp USA Spec 924 2.0 to the mark2 (944) and then the 924 mk3 (968) 3.0 with 2.5+ times the power and it all worked well and sold well until, the end when a 968 was nearly £40,000!
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PSH
PCGB Member
You miss my point Roger...the point is for decades these experts and yes they are experts, their experience is second to none, have driven everything to see the road since the launch and continue to do so to this day....the point is they still hold the 951 right up there as one of the best designs ever built even when compared to the latest cars..
This is fact, I could write volumes on what the experts have had to say about the 951 over the years, including the top designers from Porsche.
One such fact is that when a group of jornalists got together to decide amongst themselves which supercar they were going to label as the best for that year, they came to the conclusion that none of the cars on the list was as good as the 951, a car that wasn't even labelled as a supercar and thus didn't qualify, this shows you why the car is so good...
This is fact, I could write volumes on what the experts have had to say about the 951 over the years, including the top designers from Porsche.
One such fact is that when a group of jornalists got together to decide amongst themselves which supercar they were going to label as the best for that year, they came to the conclusion that none of the cars on the list was as good as the 951, a car that wasn't even labelled as a supercar and thus didn't qualify, this shows you why the car is so good...
TTM
Well-known member
PSH said:
Haha [
] - It looks like I have touched a nerve. if you reread my post(s) I am not dissing the car as a package, but the engine alone. In restrospect it was not tuned correctly right from the go and needed to be thrashed to exploit the chassis to the full. I did test drove quite a few standard 951s when I had my 944 S2 and only understood what the fuss was all about when I finally got to drive a chipped one, which I ended up buying. In the end though, this 8V engine really isn't that great, or at least it is until we realise a 16V really is that much better. If we compare a bog standard 951 with let's say an E30 M3, I do not think we can reasonably say that the Porsche engine is "better" than the BMW's.In the end experts are just there to give hints and suggest things, but in the end what matters is what we as owners feel, how we enjoy our cars and how much we are willing to spend into them so that they suit us rather than the "experts" who are paid to test drive standard cars.
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