New car and a long list to start on!

[sawood12]

Mark, to be fair, the LR manifold is only one of a multitude of mods that are getting your 400bhp. Not sure how much of that you can attribute to the inlet manifold design. Would be an interesting exercise to carry out a back to back with a stock manifold to see exactly what the difference would be.

From what i've read about inlet manifold design is that it doesn't necessarily give you more power but rather influences the shape of the power curve, for example equal length runners are better for high end power like you'd want for a race/track car, and unequal length runners are better for midrange power and torque like you'd want on a road car. And it is not about how much air they can flow like alot of tuners waffle on about (the inlet manifold is never the flow restriction in an engine), it is more about the pressure pulses and resonances that build up in the manifold runners and plenum due to the inlet valve opening and closing causing pressure waves that alternate one way when the valve is open, then the opposite as it closes. That is why on modern cars, like varioram on the 993/996/997, they attempt to have their cake and eat it by having variable geometry inlet manifolds where the volume of the manifold varies to affect the resonances in the manifold and providing a wider power/torque curve. Ideally you'd want a clever manifold that varies in plenum volume and runner length.

As Pat says, a decent BB turbo will minimise turbolag to a comparable level of any modern car that has a better layout. You don't want your turbo too close to your cylinder head as it complicates exhaust manifold design and presents the turbo inlet with a pulsing and turbulent exhaust gas flow, which turbos don't like - they want a nice steady state flow.

 

[333pg333]

ORIGINAL: DivineE

How dull! You're all right. I've stood looking at the space between the manifold and the chassis and there's no turbo going in there! The one I saw must have had extensive modification Looks like I'm going to have to be dull and stick to the standard manifold [8|]. I suppose it is more in line with my moderation is best theory. Thanks for the info on those wings. Pressure is off slightly as I've decided to hold off re-spraying until I'm happy the mechanical work is complete and everything on the shell is up to scratch. I've fitted a new set of wishbones but the replacement panels I ordered have been delayed till next week so there's nothing more to do once all the old panels have been cut out.

This gives me time to look into a carbon bonet and speak to EMC or Promax about glass fibre wings and rear bumper.

p.s. for those interested and that were reading the other threads on ECU function I discovered yesterday that the standard ECU can not only adjust ignition timing but that the 944t has individual knock sensors and can intelligently advance/retard the ignition in any of the cylinders independantly. Allowing it to decide whether only one cylinder needs to be retarded under knock conditions or all four depending on a number of factors! Not bad for one of the first production turbo's you could buy! It even has a short term overboost facility which detects if intake temperatures are safe and it has the right fuel then allows the car to run more than standard boost for short periods.[] Bet you didn't know that. Oh and the later cars actually had 274hp from the factory not 250 as stated which explains why people are still achieving over 250 on standard cars 20 years later.

Where did you find that info out about the ECU and hp Ben? I'm betting it's the first time any of us have heard that. There's one guy I know on Rennlist who is breaking down the Stock Electronics and working out how to tune them. I might run it past him.

 

[333pg333]

...oh and if you haven't already, check out this link showing my friend's 968 project if you want to see some of the complications and obvious expenses involved in shifting the turbo to the RHS on our motors. Worth it just to see his exhaust. Amazing work and let me tell you, not cheap!!

http://forums.rennlist.com/rennforums/968-forum/404449-thingo-968-turbo-project.html

 

[DivineE]

I got it from a book about the history of turbocharging by A. Graham Bell. There's a whole page devoted to the advancements made by Porsche on the 944. The information all seems to fit in with bits we already know like the use of twin walled manifolds and ceramic exhaust linings in the head (all designed to minimise heat loss and transfer maximum energy into the turbo). The rest of the book seems factually accurate too and well written so I assume its correct. I will scan it in and post it here so you guys can read the source direct.

Scott I'm not saying I disagree because if there's one thing I'm learning it's that no one understands everything about turbocharging yet, it's all still all theories but the theories in this book disagree with what you say above. He says the rate of pulses hitting the turbo are important more cylinders per turbo the better (so equall length runners are better assuring you get one pulse per cylinder rather than two hitting it together - reducing the rate) but ideally the closer you can get the turbo to the cylinders the better because the stronger the pulses the faster the turbo spools and any heat energy lost in the manifold is a double negative because a. it cannot be used by the turbo and b. it is transmitted into the engine bay which heats the air entering the engine (too many nagatives to list here for that).

333pg333 I read that thread. Looks a bit too serious for what I had in mind! Nice though[]

 

[MarkK]

Ben the plastic panels are from EMC,they are great at fitting them aswell to get good gaps (because they fit so many perhaps) plus they have a bodyshop close by that is used to getting a good result on GRP plus can respray at different levels depending on what you want qualitywise/ budget.
Looking forward to reading more about your project as and when.[]

 

[sawood12]

Ben, turbocharging is pretty well understood. The fundamental problem with a 944 turbo and lag is that it is a low compression ratio engine therefore you need higher capacity turbo's, and big turbo's take longer to spool up. Modern turbocharged engines have higher compression ratios therefore smaller turbos are required. 997 turbo's have compression ratio of 9:1 and with turbo's with variable inlet guide vanes almost eliminate lag altogether and when married upto the DSG gearbox it is barely detectable (apparently!).

The problem with exhaust gas pules is that as the pulses hit the turbo inlet what you'd want to do is change the angle of the turbo vanes to match the pulses - but you can't. That is why it is better to have more cylinders per turbo - because there is a natural smoothing affect as you get overlap of the individual pulses.

 

[333pg333]

Makes sense Scott. Guess that's one of the many advantages the 3L 6 pot Japanese motors have over ours. Modern 24v twin cam heads don't hurt either.

I know that some guys are toying with even 11:1 static c/r on a 3L Porsche motor, but this is with some pretty trick fuel and EMS going on. I see that Duke is doing a 9:5 build on his Green Hornet build. Having access to E85 is a godsend though. Sort of surprised it hasn't taken off in the UK?

Ben, I sort of hoped that link would turn you off the idea. Really way too much money involved in that venture and it's yet to be proven. That's a lot of weight to have out the front of the motor, let alone what effects shock is going to have on it structurally. I hope the best for my friend and look forward to seeing it completed of course.

 

[pauly]

I don't think highish compression on turbo charged engines is anything new, supposedly the Cosworths that won the BTCC went this route, and on a more basic level I owned a standard 2.8 capri that had a turbo technics kit fitted and that had very little lag and was very smooth.

 

[dlknight]

ORIGINAL: DivineE

Other than the above she needs a complete rear wing (not looking forward to finding out the cost on that!), a passenger side sill, new brakes, bonnet and boot struts, a few small bits plus a good service and that should get her well on the way to a full recovery

I remember reading somewhere that a mazda 626 arch is the same pattern (and alot cheaper) - http://www.nicedeals.co.uk/product_info.php?products_id=2952.

Looking at it though it doesn't seem like it would fit.... there must be more info on this somewhere...

 

[DivineE]

Thank you for that. I have a wing sorted now. Currently looking for a air con dash unit if anyone has one as mine only works on fan speed 4 and I think it would be more hassle to rebuild (if that's even possible?) than buy 2nd hand.

 

[DivineE]

ORIGINAL: MarkK

Ben the plastic panels are from EMC,they are great at fitting them aswell to get good gaps (because they fit so many perhaps) plus they have a bodyshop close by that is used to getting a good result on GRP plus can respray at different levels depending on what you want qualitywise/ budget.
Looking forward to reading more about your project as and when.[]

It's a real shame I had some very bad experiences with EMC a few years ago. I have seen now some excellent examples of work that they have done and always thought Kevin and Alex were the nicest of guys but I struggle to bring myself to use them again. Just feels like I'd have learnt nothing from my experience to go back over old ground. Maybe its silly and I should give them a chance.

Funnily enough I feel more comfortable with Promax. I think I was unfortunate to be involved when the original Promax folded and I don't feel it was handled well at the time but I beileve I judged too quickly and too harshly. Andrew and Promax have proved themselves to be a great asset to the Porsche community and many people who's opinions I trust have done well by their products.

I also cant ignor that my first shock and awe experience of a 944 turbo (which probably addicted me to tuning in the first place) was running a slightly altered version on promax's level 2 kit and producing 311hp with 380lb/ft torque very reliably on promax chips. That car really did feel seriously quick for an almost standard car!

 

[barks944]

Mine kept up with an 05 plate M3 on monday! Was gaining on it when we got to about 120. Had the slipstream advantage though. Was quite chuffed with that!

 

[sawood12]

ORIGINAL: pauly

I don't think highish compression on turbo charged engines is anything new, supposedly the Cosworths that won the BTCC went this route, and on a more basic level I owned a standard 2.8 capri that had a turbo technics kit fitted and that had very little lag and was very smooth.

i agree Pauly. piston engines are nothing new. No-one is blazing any trails. F1 cars were making almost 1000hp on turbocharged 1.5ltr engines 20yrs ago. A well tuned 2.5ltr 944 turbo engine on stock head gasket is capable of 600bhp. It has been done.

At the end of the day it boils down to ££££££ and understanding.

 

[DivineE]

ORIGINAL: barks944

Mine kept up with an 05 plate M3 on monday! Was gaining on it when we got to about 120. Had the slipstream advantage though. Was quite chuffed with that!

I can well believe it. My Z4M was extremely quick up to 100 but once you got into 4th there's no doubt a 944t with a chip would be faster. They may have 343hp but only 294lb/ft torque and they're heavier too. In fact I have a video somewhere.. hold on I'll upload it to youtube now and post a link.

 

[DivineE]

http://www.youtube.com/watch?v=FT7tPYAnSrg

There you go. Sorry about the poor quality phone camera. It plays better on the phone. Seems to have lost quality when converted by youtube

 

[333pg333]

Looked like pretty decent acceleration there Ben. Nothing to be sneezed at. Just seems to me that it would shade a chipped 951.

 

[DivineE]

ORIGINAL: 333pg333

Looked like pretty decent acceleration there Ben. Nothing to be sneezed at. Just seems to me that it would shade a chipped 951.

You have to remember 120 on the speedo is actually 108 because the car is set rigidly to show a 10% over read. 100mph in a 944 is (in the cars I've tested anyway exactly 100) and at 120 its still more like 118mph than 108.

It's unfortunate I never got the chance to do a comparison. The Z4 was very quick under 100 but you could really feel it dropping off as the speed built, comparatively a 944 feels strongest over 100. I always feel the turbo never quite gets into its stride in the low gears.

 

[Copperman05]

My 944 speedo is about 10% lower when tested against my satnav.

Edd

 

[DivineE]

That's interesting. Maybe it was something introduced during the 944's production. I notice my R32 golf was exactly 10% out too.

 

[zcacogp]

Car manufacturers will always ensure that a speedometer over-reads slightly in order that, should a person be stopped for speeding, they cannot claim that the gauge was under-reading.

Give it time, and the workings of a speedometer (particularly the old spinning magnet types) will degrade with time and the proportion of over- (or under-) reading may well change. And will vary from car to car as well.


Oli.