69 911s engine rebuild options

[bazz69s.uk]

Hay there after some advice really. I am a novice on the engine side of things at the mo. Basically i have a 69s that has been rebuilt to a 2.2s spec at its latest part of its life obviously for more power. The car is matching numbers, i have recently had compression tests done and copression in cylinders differ somewhat and show signs of rebuild in the future...

my question is i would like to have the engine rebuilt with as much power as poss, oh yes its running webbers not mfi

so what could i have done, could i have it put up to a 2.4, 2.5?? twin plug??

how , will the case need any mods?? what sort of bhp figures could i be hoping for?? the car is used for fast road use
i would like to turn the car into a beast that will shoot down most modern day cars

please some advice would be mostly appreciated

many thanks bazz

[dogslovetrucks]

Humble opinion...
Save your rare, stock 69s and build something else to race. If it's numbers matching, you'll thank yourself in a few years.

[bazz69s.uk]

it is matching numbers but will need a rebuild soon ish, so jus wanted an idea of what options for the engine without ruining originality really

thanks bazz

[304065]

Greetings Anglophone Brother from across-the-pond!

I, too started off thinking that I wanted to put a killer engine in my early long-hood. I have recently come round to the realization that original is better in many, many ways. But here is a thread I started, with input from The Known Experts.

Were I you I would heed the advice of Dr. Ing. Grady Clay: set the original engine aside and build yourself a brutal 2,8 for terrorizing your local autoroute.

Good luck! Here is the thread to which I refer.

Suggestions for warmed over 2.0 901/05?

[Eagledriver]

I concure with the above advice except I'd build a 3 litre with carbs for my second engine. You could even use the carbs you already have with different settings. A 3.0 engine is cheaper to build than a 2.8 and will last longer as well.

You'll never make your original engine fast enough without compromising it's originality.

-Andy

[kenikh]

Take some advice from a fellow '69S owner who has gone through every thought you will ever have on this car. The '69S engine case is ill suited for extreme hot rodding. It has the weakest, albeit lightest engine case ever put in a 911. Anything over 210HP and an 85mm (exotic options in cylinders can get you to 87.5mm) bore will begin putting that incredibly valuable engine case in jeapordy. You have two real options:

The smartest option mentioned above: building a new, ultra fast motor (I'd suggest a 2.8/3.2 short stroke; the first if money is no object, the second if it is)
or
Do what I did: resign yourself to 200ish HP in a car that weighs near 2000 lbs and build a short gearbox for trouncing newer vehicles.

I am in the process of bulding a 2.3L rev monster that will put fear in the heart of 2.7 liter RSs, but admittedly will never scare the Evo driver. That's the way it goes.

If you want a brilliant and original car, go option two. If ultimate testosterone is your bag, then build a big engine.

That's 2 years of research, headache and money distilled into one simple little pill. All you have to do is take it.

[Grady Clay]

John,

“Dr. Ing. Grady Clay” you are too much. The real Dr. Grady Clays are my grandfather (MD and Emory professor) and father (Emory Honorary PhD). I’m the third.


bazz, tell us more about your car and intended use.

As I have been encouraging John Cramer, you might be best to return your engine to original. If that isn’t a current procedure, at least acquire the necessary parts.

The most fun and relatively period correct is starting with a MFI 2.4 and converting it to 2.8S (92x70.4=2808 cc). The cost is not for the faint of heart or thin wallet. On the other side it maintains the lightweight characteristic for the car and is very powerful. This is a fairly common engine build and a lot has been written on the subject.

The basics are a standard 2.4T with MFI. The MFI and heads can be converted for use with S cams. The P&Cs are standard ’73 RSR Mahle Nikasil. One feature of using these P&Cs in this use is very high CR (~12:1). This necessitates twin plugs and very high (race) octane petrol.

If pump petrol is necessary, the P&Cs of choice are the ’73 Carrera 2.7 RS Mahle Nikasil (8.5:1 CR). Twin plugs are still of benefit.

I agree that a short geared transmission and ZF LSD will be a great benefit. I would use a ’70-’71 type 911 transmission in place of your 901. This is an easy swap and this also allows use of the larger 225 mm clutch common from 2.2 to 3.2.

Starting with a 3.0 is less expense and more durable but (IMHO) necessitates converting to a 915 transmission. All this is also heavier.


OK, what do you do?

You will get lots of advice, most of it great. Check your wallet first.

I think your first efforts should be to accumulate the parts necessary to rebuild your engine as original. High on the list is original MFI. That also includes all the systems in your 911S.

If your engine needs to come out, buy a carbureted engine to keep the 911 running. It can be anything from a 2.0 to 3.0.

The mods I propose above can be done while your 911S is still in service. Even for first-time DIY, with this Forum’s help, the engine/transmission swap is only a weekend project. Being prepared for that weekend is a year-long project.

Best,
Grady

[viejopatron]

Hi Bazz,

I would keep the current mill, however a top end overhaul might be a considered short term measure. Has exhaust been optimized?

Listen closely to comments touching on cost. It goes way up easily.

Cheers.

[bazz69s.uk]

Thanks for the great advice guys, i think the best idea is to source something of the 3ltr variety to drop in while rebulding the original engine , to the spec it is now, and possibly putting original mfi back on. Would the mfi give the car more bhp and torque??

many thanks again fellaz i know you know ya stuff!!

bazz

[kenikh]

The factory specs show that MFI is good for about 10 HP on the 2 liter 'S' over stock Webers. If you used PMOs the difference would be negligible.