944 2.5 forged pistons + bore questions.

[ihatesissycars]

Hi all,

If I were to rebuild a 2.5 944 engine and wanted to uprate a few things namely pistons, rods, main studs etc what would my options be?

I have a 2/5 lux and I'm really leaning towards to supercharger kits available for this engine (2.5 8v) but the initial power output is, in the grand scheme of things quite low due to the c/r and how much boost it can take so I wanted to research engine upgrades to take more boost at a later date.

Alot of uprated engine specs I've read about all seem to have uprated rods and forged pistons with a standard crank, are the standard units weak?

Could I just plonk in a low comp turbo engine later on and charge that?

Are bits interchangeable between the 2.5 n/a and forced engines?

Would a turbo head be a better bet than my n/a one?

Does anyone have any other info applicable in any way to this they want to share?

Ta!

[HAB]

If I was you, I'd sell the car and buy a 944 Turbo.

Edited by HAB on Friday 17th August 12:41

[ihatesissycars]

I don't want to because I'd then have nothing to do plus to get the same power I want out of a turbo I'd have to spend loads on that too and this car I have now only cost me £800. A decent turbo is £5k+. It'd cost me more if starting with a turbo.

[Conian]

Hey Sissy... I somehow knew this thread would be from you!

I can understand why ya wanna do lots of fun stuff to ya car... but at the end of the day, the 944T was built to take extra power and handle etc, with all the work you're planning it will soon easily leap up to 5k of spending, and then you got a lot of hassle making it all work nice.

And if you ever come to sell it there is no way you'd get back the money you spent, whereas a 944T you wouldnt lose much on.

[ihatesissycars]

I know what you're saying and yes it does make sens to start with that however this car is £500 to insure for me, a turbo is £3000, Owning a turbo isn't an option for me yet superharging my car barely makes any difference to my present insurance plus yes its work etc etc but that is my thing, I love doing it and getting it working, you should see my capri!! The 944 will be a piece of piss compared to what I did to that as everything is bolt on stuff, plug and play and it'll be unique and exactly how I want it. I understand what you're saying, really I do but owning a T isn't an option for me.

[Conian]

What will the insurance be like when youve strapped a charger onto it?

Make it nice big charger, sticking through the bonnet with a spinning belt like Mad Max

[ihatesissycars]

You're being silly now. . . . . . . or are you!!!!

It was like another £150 for the charger and other mods (konis, brakes etc) and another £200 if I was to plug my nitrous kit into the car aswell.

[Conian]

I can't go long without being silly

Those sticky uppy chargers do work on some cars tho... eg dodge chragers, mad max... ford fiesta

ah damn i went silly again right at the end there look... doh!

[hartech]

A supercharger works a little differently to an exhaust turbo charger in that it tends to flow more air at lower revs and run out of steam more at the top end (depending on its size of course - but too big uses a lot of power to run).

This helps with the compression ratio problem, enabling you to get away with more compression because it is not as high at full revs on full load.

If the supercharger is relatively small you may get away with std pistons or you could always machine a dish in the top (mahle forged pistons are strong enough).

You could fit turbo pistons but these may lower the compression ratio too much at low speeds to get good power.

You do not need a turbo head - the std one will be OK.

Best advice is to buy a turbo - better brakes, better transmission and more able to cope with the extra torque.

Baz

[ihatesissycars]

Hmmm so mahle do some, any outlets for them in the UK?

I know a turbo would be a better place to start from, really I agree but there's no way I'm ever going to give an insurance man £3k, no way!

My car is fairly well specc'd up at the moment now though, koni springs and dampers, turbo rear brakes and a brake kit from porscheshop on the front. The only weak point is box and non lsd diff but thats a gearbox change away from being sorted.

All the above mentioned upgrade are new and fresh unlike a 100,000 mile old turbo which would no doubt need some money thrown at it so with my route I'll end up with a car which is spec'd up as well as a turbo model and cost less and looks the way I want it too. WIn win!

Keeps me busy too. I'[ve I had nothing to tinker with I'd go insane!

Do you know how strong the standard engine components are? Also, now that you've told me I won't bother with a turbo head but out of curiousity what are the differences?

Ps, thankyou for your help!

Edited by ihatesissycars on Saturday 18th August 11:56