Porsche 944 turbo road to racecar.

[lightyear]

We get caught up in always wanting to go faster. We know how, or we learn how, and we do it. It's probably no different to gambling addiction.??
For me, a basic MX5 like my old red one with track mods and some aero has to be the best value track car. 1:50 at the Island is quick enough to annoy a few fast cars. But you get bored of it and want to go faster. The MX5 I track now is still fairly tame (although it looks like a race car now), but it's a costing a little more in maintenance and running with its turbo power. Now it seems to be sorted I am enjoying it, and don't regret it. And if it does a 1:43 tomorrow I will be happy and it will all be worth it. Playing with the car and developing it is half the fun. As long as you get to drive the thing regularly and it's reliable, it's all happy days.

[ENGINR]

"As long as you get to drive the thing regularly and it's reliable, it's all happy days."

I think this is the problem though - alot of us are taking reliable cars and in the quest to go faster are spending huge amounts of time and $$$ turning them into temporary and unreliable pigs that we don't get to drive regularly. I got my car out in October last year, broke the exhaust manifold then only got it out again late April this year after having the manifold repaired and making a few (unnecessary but just-HAD-TO-HAVE) modifications to subframes and engine mounts. That's one track day in 6 months. The lack of a proper garage, crap cold and wet weather and long days at work have really diminished the enthusiasm level to spin the spanners for even routine maintenance work.

A mate at work has a stock standard MX5 that he runs at a track event almost every 2nd weekend and another mate who has a stock standard CC Lancer Glxi coupe he picked up for $150, spent $350 on wheels and tyres and he runs it in khanacrosses, hillclimbs and sprints and just generally thrashes the crap out of with zero fucks given.

[333pg333]

There's a lot to be said for that kinda thing. As you and others have mentioned, a stock-ish shitter that you can just drive and have some fun with is probably the way to go. Might have to think about that in the future.

[Sonicevo]

Slow progress and financially crippling. Next motor will have to be the last no matter what. It's not far off and should be a big improvement. As for pumping up anyone's enthusiasm I'm not that guy anymore. It's all too hard and expensive and stupid. Just hope there is still a glimmer of fun to be had.

That's the time attack bandwagon mate! Eventually you look back see how much $ you've spent vs how much fun you've had and the pin is pulled. I can think of numerous people in this category over the years.

[333pg333]

Yeah, spot on Mick. It's crazy. Pity there's no sponsorship and a series but that's in Neverland. Think it's Lawnbowls for me. ;-)

[Sonicevo]

You're better off just getting it going again, winding it back a bit and making it reliable and start doing Porsche club sprints in it again with you driving. Forget about the TA arms race and get back to why you used to drive the car on track. Get yourself a tow car and a trailer and start going to events again by yourself without needing to pay for workshop support. Even winding the engine back and removing some of the aero to make it easier to transport you'd likely give the cup cars a good run for their money at the club days. That'd be far more satisfaction than another $50k and no trophy at WTAC.

[fatz]

You're better off just getting it going again, winding it back a bit and making it reliable and start doing Porsche club sprints in it again with you driving. Forget about the TA arms race and get back to why you used to drive the car on track. Get yourself a tow car and a trailer and start going to events again by yourself without needing to pay for workshop support. Even winding the engine back and removing some of the aero to make it easier to transport you'd likely give the cup cars a good run for their money at the club days. That'd be far more satisfaction than another $50k and no trophy at WTAC.

So true
Ta will fix out in a few years as well like all next big things

[333pg333]

You're better off just getting it going again, winding it back a bit and making it reliable and start doing Porsche club sprints in it again with you driving. Forget about the TA arms race and get back to why you used to drive the car on track. Get yourself a tow car and a trailer and start going to events again by yourself without needing to pay for workshop support. Even winding the engine back and removing some of the aero to make it easier to transport you'd likely give the cup cars a good run for their money at the club days. That'd be far more satisfaction than another $50k and no trophy at WTAC.

Still trying to make it to this year's TA. Motor isn't far off being finished and it should give us a real improvement over what we had...but after that, it's anyone's guess. You're right in what you say and I do totally get it. At this stage we'll try and do TA and after that I might just sell it...or try.

[333pg333]

We're now committed to the Electric Water pump. Looking at options. Just wondering if you can have too much flow rate or is that just too general a question? The Davies-Craig units max out at 39 gallons / 150 ltrs per min where one I've been recommended out of the US has a flow rate of 55 gallons / 208 ltrs per minute. Wondering if too much of a good thing is, well, too much??

[dougmo]

you can always restrict it if need be with a plate with holes in it, high water pressure helps limit cavitation too (to an extent)

[333pg333]

Yeah that's sorta what I figured. Having too much is controllable. Better than not enough. Can run it into different areas of head/block too.

[profi]

My car has the plastic 80L davies craig water pump. No restriction, just a thermostat and works perfectly

[brypar]

you can always restrict it if need be with a plate with holes in it, high water pressure helps limit cavitation too (to an extent)

Best way to do it is with a dual half bridge and run pwm.

[333pg333]

Not sure quite how to calculate necessary flow rate but good to know that at least 2 cars run the D-Craig successfully. Going to make a call very soon if we'll even be at the event this year. It's really too late already.

[333pg333]

As usual there have been delays but now they're 99% done and just about to put it in the crate to ship down to us. Going to be stupidly tight (time / money) to get it ready for this year's WTAC and I was really close to withdrawing. However the cams finally came through although the head needed to be further modified to allow the intake cam to turn.

To package the adj cam wheels means that the crank pulley is small. An extra tensioner has been established to maximise belt wrap. Concern is how the belt is going react at over 8000rpm. Assuming Michael Mount (US race-motor builder) has run his n/a motors to similar rpms I am hopeful that we have also taken every precaution here.

The next question was what housing to run with the turbo. As we're sticking with the GTX3582r we have the choice of the .82, 1.06 or even the .63 (won't be using this). Speaking with a Swedish racer (actual Swede!) he is quite sure that the 1.06 is the way to go as he has similar motor and same turbo and I'm inclined to believe his real world testing. However he also now has Sequential gearbag which probably means he can run a larger housing and get away with it. Others, such as the engine builder seem to think that the .82 should be sufficient. The compromise is between driveability/spool and backpressure/strangulation. While the motor has been built to spin out to about 8800rpm we need to maximise mid range rather than top end with the H pattern gearbox. With the 94mm stroker crank (stock is 88mm) I don't know how this is going to affect the motor in the upper rpms either. Having said that, the rods are actually longer than stock by 2mm by designing the pin location in the piston to assist. Don't know the actual rod/piston ratio yet but not as bad as I first thought.

Another thing is the intake. Again, as we need early to mid range tq, I'm not so sure if we'll go with a short runner intake like Swedish guy. Our memories are fresher with the 2.5 8v racemotor which was a bit laggy, so we need to allow for the extra 700cc's and stroker crank plus all the modifications to allow the motor to rev quickly. So I'm caught between smaller housing/longer runners or just trust the motor and go with the larger housing and shorter runners to allow the motor to breath more efficiently at the top end.

Any turbo plotting experts are free to chime in. :-)

Basic specs so far are:

Intake runners: Approx 280mm - 50mm OD.
Head: Pretty high lift / short duration cams high flow head
Valves: 41mm int / 35mm ex

Exhaust is 3650mm / 143" from turbo back. 3" in diameter.

The Crossover is 880mm / 34.6" from collector to turbo. 2.25" in diameter.

Headers are all different. They average 685mm / 27" to collector. 1.75"
diameter.

Collector is 125mm / 4.9" long.
Turbo: GTX3582r
Compressor wheel specs
62.5mm inducer
82.5mm exducer

Turbine wheel specs
68mm 84 Trim