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beepbeep beepbeep is offline
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Join Date: Jun 2001
Location: Sweden
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There is no stock 911 engine made in 1985 that is displacing 3.0 liters. 930's had 3.3L and Carreras 3.2L engines in 1985.

Other than that, I'm with Juan on this one. your best and cheapest alternative for attaining lot's of power is selling your stock engine, whatever it is and going for turbo-converted N/A 3.6 engine.

Note that you shouldn't look for 3.6 Turbo engine but naturally aspirated 3.6 engine, from 964 or such.

It's then matter of changing pistons and rods to better/stronger aftermarket items with lower C/R, fitting a good EFI and dual or single turbochargers together with new headers.

Two T70 turbochargers would be too big and lag too irritating in anything else but dragracing, but two GT30BB's would fit just perfect.

Building a powerful engine is black science where you have to take account of different aspects like:

1. How much power?
2. Can i do it with my stock engine or is it cheaper/easier/better just to sell it and buy a better base to build on?
3. How much can I do myself?
4. Has it been done before and are there any expensive misstakes that I can learn from?

Unfortunately, many people are stuck to some sort of emotional ties to their stock engines and pour insane amounts of money in order to tune them despite the fact that they are bad fundaments to build hi-po engine on to begin with... It's even worse with N/A engines.
This behaviour leads to costly excursions of "I've spent 13000$ on bored-out CIS motor to get 30hp extra" -type.

It's much better to keep head cold and understand that budget for building such engine might be bigger than what base engine costs itself and that there are big savings to be done by just getting what you need (case, heads, crank, intake) and building on it with custom parts knowing that you cannot re-use stock parts anyway.

Reason I stated turbo-converted 3.6 motor as best/most priceworthy base for no-holds-barred hi-po 911 motor are following:

1. It's already twin-plugged.
2. It's cheaper than 3.6TT which is single plugged.
3. You have no use of its OEM pistons, rods and turbocharger anyway, so buying 3.6TT engine isn't of any good.
4. All 3.6 engines are allready built for EFI (fuel-rails are there) while 930 engines have pesky CIS system and bad-flowing intake and heads.
5. I have a friend who did all above, I have seen his (very impressive) dyno papers.

Alternatives when building 400+ HP engines:

930 engines are cheap to tune to approximately 350hp...after that it gets costly. There is nothing magical about them compared to 3.2 motors. You will spend more money to rectify their inherent weaknes compared with starting with stock 3.2 motor if gunning for 400HP+ range.

3.2 Carrera engines are little better. It's cheaper to make big power engines from them but they will never come to 3.6 output as long as you don't swap almost everything, effectivly making them like 3.6 engines.

3.6 engines are the best, have all updates done and bigger displacement to boot. 600HP is possible and relativly easy.


So my final suggestion:

Throw all emotional/traditionalistic thinking through the window and think purely from engineering/economic standpoint.

3.6 N/A stock engine from totaled car, prefferably w/o engine harness (=cheaper)
JE pistons, Carillo rods, 8.0:1 C/R
2 x GT30BB turbochargers (BB=ball bearing)
6 x 903cc Siemens injector
custom intercooler and headers
dual throttles
GT2 Evo cams
Motec EFI with twin-plug direct-fire ignition
Stock flywheel (trust me on this)
Heads don't need to be ported
Stronger valve springs if running more than 1.2 bar of boost (trust me on this)
G50/52 transmission with Guard Transmission billet cro-molly LSD and oil-cooling
Fitting KEP clutch.
Coilovers all around (a must if fitting G50 transmission)
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Thank you for your time,

Last edited by beepbeep; 10-30-2004 at 09:40 AM..
Old 10-30-2004, 06:39 AM
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