Piston & Rod upgrade or not?
- Thread starter slickv8
- Start date
924Srr27l
New member
Indi9xx said:
The odd one out then is the later Turbo, I can understand one spec for all 100m bore / short stroke 2.5 litre engines , and another for the larger 104mm piston short stroke 2.7, and the 104mm / long stroke 3.0 S2 but for some reason Porsche decided to fit the 3.0 S2 also to the later turbo?
I'm guessing the bigger engine versions are heavier ? I've not got 2.5. 2.7 or 3.0 shafts fitted but modified half weighted polished versions from Broadfoot Racing USA. This was the best decision as I wasn't sure to fit shafts or delete!
R
924Srr27l
New member
blade7 said:
Looking at the ever popular 3.0 S2 v 2.5T argument this is probably why Porsche didn't go 3.0 turbo.
I'm sure they must of tested this configuration and decided to go for the less erratic, more drivable N/A with a
twin cam head, bigger bore and longer stroke (511cc more).
R
924Srr27l
New member
blade7 said:924Srr27l said:
I'm no S2 fan also if that's what your chuckling at ?
I drove 2 of them in one year when I owned the Variable Valve timed 968 (Mapped to 255bhp) and thought they were both really
sluggish which was bound to happen against a peppy 968! but I wouldn't even consider one now either as the 24 is much quicker.
R
Indi9xx
New member
Porsche went 3.0 Turbo with the 968 Turbo S and RS of course, which was at one point going to be the 944S3 (in folklaw)
But that was a serious under performer as standard, and as usual, it looks like that was intentional, its very easy to get their power on form.
But my findings, to be honest, are that the big turbo engines when tuned are over kill.. The extra CC's of the 2.8, 3.0 and 3.2 Turbos make for a nicer drive off boost, but with a decent manifold, intercooler, turbo and exhaust, they are lethal weapons.. I have had a 944 turbo with one of our 3.2 engines in it able to light up the tyres at 125 mph, which I thought was clutch slipping, but as I played with the slippage thinking (oh here we go, needs a heavier clutch) a bend in the road (private of course) and each blip of the throttle and rev rise (which I thought was the clutch) had the car sliding sideways... Which is ok at slower speeds, but at 120 mph, wheel spin on demand is fricking scarey and to be honest, probably makes for a much slower car, because you are scared to use the throttle on demand as much.
Over the years I have now learned that the 2.5 Turbo is so easy to tune and bolt lots of goodies onto it safely, there isnt much point in going large with the engines, other than to get more power off boost.
For the sake of the S2 versus turbo argument, I own several of both, and to be honest, it is horses for courses.. When on the motorway being harrassed by a BMW M/Ferrari etc, I often wish I wasnt in an S2 and was in a tuned turbo, as blowing the doors off some more modern metal is extremely good fun... But for low speed fun on twisty narrow country lanes I love the immediate power of an S2... But having said that, a 924S with a 968 engine is probably my favourite road car package... Immediate power, light weight, narrow tyres for oversteer if you want it, but plenty of grip in the dry to put the power down.
But that was a serious under performer as standard, and as usual, it looks like that was intentional, its very easy to get their power on form.
But my findings, to be honest, are that the big turbo engines when tuned are over kill.. The extra CC's of the 2.8, 3.0 and 3.2 Turbos make for a nicer drive off boost, but with a decent manifold, intercooler, turbo and exhaust, they are lethal weapons.. I have had a 944 turbo with one of our 3.2 engines in it able to light up the tyres at 125 mph, which I thought was clutch slipping, but as I played with the slippage thinking (oh here we go, needs a heavier clutch) a bend in the road (private of course) and each blip of the throttle and rev rise (which I thought was the clutch) had the car sliding sideways... Which is ok at slower speeds, but at 120 mph, wheel spin on demand is fricking scarey and to be honest, probably makes for a much slower car, because you are scared to use the throttle on demand as much.
Over the years I have now learned that the 2.5 Turbo is so easy to tune and bolt lots of goodies onto it safely, there isnt much point in going large with the engines, other than to get more power off boost.
For the sake of the S2 versus turbo argument, I own several of both, and to be honest, it is horses for courses.. When on the motorway being harrassed by a BMW M/Ferrari etc, I often wish I wasnt in an S2 and was in a tuned turbo, as blowing the doors off some more modern metal is extremely good fun... But for low speed fun on twisty narrow country lanes I love the immediate power of an S2... But having said that, a 924S with a 968 engine is probably my favourite road car package... Immediate power, light weight, narrow tyres for oversteer if you want it, but plenty of grip in the dry to put the power down.
PSH
PCGB Member
I have to say that I'm very happy with my own car's 'off boost' performance, not that it takes long to get on boost you understand, especially if I set the 'duty cycle' high, a luxury that I didn't have when using an MBC... anyway although it's probably impossible to state which mod affects my car's 'off boost' performance the most due to having so much done in the one go there are a number of mods that may help the most:
1: crank scraper
2: higher capacity
3: slightly lightened flywheel
4: full race pistons with very thin rings thus less friction
5: custom free flow exhaust including turbo downpipe (less of an effect but I'm sure that it helps)
The result is that the car is a delight to drive when off boost, it just feels 'all powerful' and when on boost? ....well you just hang on.....and I still haven't taken her out of her safe mode yet...
Pete
1: crank scraper
2: higher capacity
3: slightly lightened flywheel
4: full race pistons with very thin rings thus less friction
5: custom free flow exhaust including turbo downpipe (less of an effect but I'm sure that it helps)
The result is that the car is a delight to drive when off boost, it just feels 'all powerful' and when on boost? ....well you just hang on.....and I still haven't taken her out of her safe mode yet...
Pete
924Srr27l
New member
[b said:
Yeah, Narrow track, Manual steering, Imagine that but faster still with 6 & 4 piston brakes and 250kg less vehicle weight!
Oh but without the oversteer (I don't have any, but I need to get some as the front pushes a little)
R
www.924srr27l.co.uk
Indi9xx
New member
The last one we built was last year for the Chairman of TiPEC who has a couple of 924S examples, one standard, the other we installed a 968 3.0 16v engine and DME with the engine loom modified to plug into the original 924S electrical system, so completely reversible, with adapters for the 924S fuel line location and a cone filter, we used a single mass flywheel and sprung clutch rather than the unsprung 968 one (still genuine), and the brakes were bigger disks on the front and rear and four pot Porsche brembo's all round. Litterally every part was a Genuine Porsche part except for the engine loom (standard 968 modified to plug straight into the 924S body looms), DME chip, and the 968 fuel rail to 924 fuel line adapters.
Whenever we do something like that, we try to make it so anyone with (in this case) a 968, 924S/944 Factory workshop manual could work on the car, including main dealers, and all the parts are marked and available from the main dealer network as well as the aftermarket.
The customer then complimented it with a GAZ coil over kit, but with our springs and solid top mounts, some 968 16 inch cup one wheels.. So if you see a red 968 at shows, with Martini graphics and a 968 engine, say hi to the owner, he is a really nice chap and would probably be really interested in your project, not to mention would be happy to take you out so you can experience the road noise from the top mounts.
Performance should be in the ball park of about 240 BHP and 225 ft-lbs of torque, I would not hazard to guess his actual output, the engine had a head rebuild with new guides as part of the work (which can loose 968s about 20 bhp when worn beyond 20,000 to 30,000 miles) and the intake adapters and cone filter were not parts we would usually use with the 968 when we install our off the peg chip, but they tend to get around 260bhp and 255 ft-lbs (calculated flywheel figures) on a DD Chassis dyno.
If it were my car, I would probably have seen if some 16inch late offset 944 teledials coud have been made to fit somehow and mounted the cone filter a little like yours, but we wanted to keep it as "Porsche parts bin" as possible and the throttle body to MAF sensor adapter was sourced from another Porsche model, but in testing we found almost equal under bonnet temperatures either in the inner wing or counter intuitivey near the radiator on previous projects (except when stuck in traffic)
Actually, thinking back, this was one of the less painful customer projects, with the owner fully following our advice, the plan was pretty much set from the moment he made the decision to go 968 powered and because it is about the 10th 944S2 or 968 powered 924S/pre-86-944 conversion we had done, much of it was quite straight forward, with the pre-86 944 using the same fuel lines and pretty much the same fuse box and dashboard connectors for the engine loom to tie into.
Whenever we do something like that, we try to make it so anyone with (in this case) a 968, 924S/944 Factory workshop manual could work on the car, including main dealers, and all the parts are marked and available from the main dealer network as well as the aftermarket.
The customer then complimented it with a GAZ coil over kit, but with our springs and solid top mounts, some 968 16 inch cup one wheels.. So if you see a red 968 at shows, with Martini graphics and a 968 engine, say hi to the owner, he is a really nice chap and would probably be really interested in your project, not to mention would be happy to take you out so you can experience the road noise from the top mounts.
Performance should be in the ball park of about 240 BHP and 225 ft-lbs of torque, I would not hazard to guess his actual output, the engine had a head rebuild with new guides as part of the work (which can loose 968s about 20 bhp when worn beyond 20,000 to 30,000 miles) and the intake adapters and cone filter were not parts we would usually use with the 968 when we install our off the peg chip, but they tend to get around 260bhp and 255 ft-lbs (calculated flywheel figures) on a DD Chassis dyno.
If it were my car, I would probably have seen if some 16inch late offset 944 teledials coud have been made to fit somehow and mounted the cone filter a little like yours, but we wanted to keep it as "Porsche parts bin" as possible and the throttle body to MAF sensor adapter was sourced from another Porsche model, but in testing we found almost equal under bonnet temperatures either in the inner wing or counter intuitivey near the radiator on previous projects (except when stuck in traffic)
Actually, thinking back, this was one of the less painful customer projects, with the owner fully following our advice, the plan was pretty much set from the moment he made the decision to go 968 powered and because it is about the 10th 944S2 or 968 powered 924S/pre-86-944 conversion we had done, much of it was quite straight forward, with the pre-86 944 using the same fuel lines and pretty much the same fuse box and dashboard connectors for the engine loom to tie into.
Indi9xx
New member
And a shot to show it fits under the bonnet lol
One other part that was modified or manufactured was a aluminium bracket to allow the use of the 968 header tank, which was critical because we wanted the customer to be able to use Genuine 968 hoses and front coolant rail on his car, so if anyone else ever works on it they can pretty much know that "If its under the bonnet its 968, if its not under the bonnet it is 924S, apart from the brakes, which are a cunning mix of Porsche parts which is a slight secret)
One other part that was modified or manufactured was a aluminium bracket to allow the use of the 968 header tank, which was critical because we wanted the customer to be able to use Genuine 968 hoses and front coolant rail on his car, so if anyone else ever works on it they can pretty much know that "If its under the bonnet its 968, if its not under the bonnet it is 924S, apart from the brakes, which are a cunning mix of Porsche parts which is a slight secret)
blade7
Well-known member
PSH said:I have to say that I'm very happy with my own car's 'off boost' performance, not that it takes long to get on boost you understand, especially if I set the 'duty cycle' high, a luxury that I didn't have when using an MBC... anyway although it's probably impossible to state which mod affects my car's 'off boost' performance the most due to having so much done in the one go there are a number of mods that may help the most:
1: crank scraper
2: higher capacity
3: slightly lightened flywheel
4: full race pistons with very thin rings thus less friction
5: custom free flow exhaust including turbo downpipe (less of an effect but I'm sure that it helps)
The result is that the car is a delight to drive when off boost, it just feels 'all powerful' and when on boost? ....well you just hang on.....and I still haven't taken her out of her safe mode yet...
Pete
A Lindsey super 61 must have more lag than the original 86 turbocharger ?
PSH
PCGB Member
blade7 said:PSH said:I have to say that I'm very happy with my own car's 'off boost' performance, not that it takes long to get on boost you understand, especially if I set the 'duty cycle' high, a luxury that I didn't have when using an MBC... anyway although it's probably impossible to state which mod affects my car's 'off boost' performance the most due to having so much done in the one go there are a number of mods that may help the most:
1: crank scraper
2: higher capacity
3: slightly lightened flywheel
4: full race pistons with very thin rings thus less friction
5: custom free flow exhaust including turbo downpipe (less of an effect but I'm sure that it helps)
The result is that the car is a delight to drive when off boost, it just feels 'all powerful' and when on boost? ....well you just hang on.....and I still haven't taken her out of her safe mode yet...
Pete
A Lindsey super 61 must have more lag than the original 86 turbocharger ?
It certainly has, but since the rebuild with the components listed above this has changed things greatly, I doubt that it's back to the smaller turbo lag but if it isn't, it's not far off. Something else that I had forgotten about which has nothing to do with off boost performance but which does effect on boost and that's the custom spacer that I turned up for the wastegate, (details in my build thread) this does have a big effect on how the system holds boost.
Right now I'm missing my car as it's still in the bodyshop, hope to get her back next week...fingers crossed...
Pete
PSH
PCGB Member
blade7 said:To save me trawling back through your thread what wastegate do you have and how does the spacer fit ? If it's dry tomorrow I'm taking mine out for a blast [
I have the LR DPW, must be 15 years old now, I rebuilt it with new diaphragm and spring as both were toast, I then machined up a spacer to fit internally between spring and casing, IIRC it was 4.5mm thick but could be mistaken? You can buy shims from LR, I think that they recommend to fit no more than 4, these can be fitted without the need for a complete strip down. However, the problem with their design, though, is that for each shim that you fit you loose that amount of opening for the valve, you'd have to look at their shims to see what I mean, a poor design IMHO.
Pete
PSH
PCGB Member
the wastegate is only as good as the spring it contains....my mind is a little fried these days but even with a DPW the valve will open before whatever you've set the boost at. On the standard system Porsche designed it so that you've losing boost before you hit full boost, you'll keep doing this even with a DPW and a weak wastegate spring. One big advantage of a stronger spring is less lag as it holds the valve tightly closed for longer as the boost builds to whatever you have the EBC set to for max. I can't remember what the LR spring is set for, perhaps 8 or 10 psi, once you get to this the ports are then fighting to hold the boost but you'll still be losing some, add exhaust back pressure into the mix and this can vary even more and thus causing extra lag. Fit a stronger spring or add a spacer/shim and you'll have a more responsive engine. You can go too far, though, after all, you do need that valve to open at some point....
As I said my memory is a little faded these days, as is my thought process but I think that covers some of it?
As I said my memory is a little faded these days, as is my thought process but I think that covers some of it?
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