How to upgrade a 911T engine to a 911S engine.

Phil1000 · 10-27-2003, 02:08 PM

I am looking into buying a 911T but I find the engine HP a little low. I would like to get it to a 911S specs, one of the local Porsche specialists told me that it is cheaper to go to a 3 L engine than to change all the internals of the engine. From what I understand from my documentation I only got to get the compression ratio up and for that I don’t need to change all the internals of the engine because the bore, stroke and displacement are the same on the T and S engine”

Could you clarify this for me and is this kind of information included in your book about engine rebuild?

Thanks,

Philippe

Rot 911 · 10-27-2003, 02:21 PM

Pistons, cams, MFI or carbs. Get Waynes Engine Rebuild Book and you can find out more there.

Jay Auskin · 10-27-2003, 02:23 PM

You'd need the following S components:

--S pistons & cylinders
--S cams
--S MFI components (if your car has MFI) ($$$$)
(did I leave anything out??)

It wouldn't be too cheap. If it's a street car, there may be other "upgrade" options to get better bang for the buck. If the T runs well, I say drive it, and start gathering components to build a nice RS spec 2.7L.

...just my opinion, but it all depends how quickly you want more power, and how big your budget is.

911pcars · 10-27-2003, 04:10 PM

Don't forget the 911S crank, connecting rods and distributor. In addition, you'll need a S engine shroud (red). The only thing you won't have to change is the case, intermediate shaft, rockers, oil pump, engine oil cooler and engine sheet metal.

You might be better off starting with a 3 liter engine.

Sherwood
http://members.rennlist.org/911pcars

Tim Walsh · Tim Walsh's Garage

I realize you're mentioning EVERYTHING that you need to change from a T to a S engine but lots of it isn't totally necasary. The dizzy can be recurved, the T crank while not counterweighted still works well, the Rods are just fine without the nitriting, etc. Yes its not exactly but it'll still make 95% of the HP a S engine makes

TimT · 10-27-2003, 05:14 PM

You guys forgot to mention hogging out the headss to S specs.

The S cam wont be to happy breathing through those itty bitty T ports

snowman · 06:23 PM

The crank is a big deal. The S crank is forged vs cast in the T, not to mention the counter weights. The cylinders are cast iron in the T vs Al in the S. The pistons are also cast vs forged, a very big deal. The Rods can be salvaged if they are shot peened and balanced and nitrited.

The power comes from the heads and cam. The heads must be ported at a mininum to match the S ones. Of course the cams must be changed. The distributor is a minor consideration.

The cooling must be improved by adding an external oil cooler, like the S one.

All in all it ain't worth the price, Get an S to begin with or forget it.

On the other hand a t CAN be souped up a bit. just rember it will never be a real S. The biggest bang for the buck is not worth doing, ie upping the compression ratio. The downside being running race gas just ain't worth the price, for everyday driving.

A 3.0 will give you more useful bang for the buck than any other mod you can make. And you will be able to afford to drive it, and you will beat any REAL S out there (that is a stock 2.0, 2.2, 2.4 that uses pump gas).

One could say that a small block chevy motor will give even more bang for the buck, but then it ain't a Porsche any more is it? And a Chevy will break down more with the same type of use. That is of course unless you use very expensive aftermarket parts that are the same quality Porsche uses to run high rpm without breaking.

PS

What I did to my 2.2 T engine

Balanced crank, rods, pistons, flywheel.

Had the crank and rods shot peened by Metal Improvement Company.

Minor head porting, removed any flashing or rough spots, especially on short side radius.

Back cut exhaust valves

5 angle valve cut on intakes

retarded valve timing 10 degrees. Check valve to piston clearence to make sure its ok. This seems to add more HP than any other change, and is much cheeper than going to E cams for almost the exact same result. ie about 150 hp. Note this can be verified by desktop dyno 2000 or a real dyno.

Add extra cooler.

snowman · 10-27-2003, 06:31 PM

Quote:

Originally posted by TimT
You guys forgot to mention hogging out the headss to S specs.

The S cam wont be to happy breathing through those itty bitty T ports

I have done some acutal flow testing of stock T heads and I would suggest leaving the ports alone. The S head actually hurts the lower rpm performance and dosen't add much of anything at high rpm, unless you like running at 8000 plus all the time.

I suspect the larger ports were more of a marketing thing than a real practical thing. Maybe the race engine used the larger port effectively, but there is no reason any engine less than 300 hp needs it. And to get 300 HP out of one of these little engines, one MUST run 8000 RPM plus.

911pcars · 10-27-2003, 08:44 PM

Forgot to mention that S intake and exhaust valves are also larger than the T versions.

Although there are end-arounds to get a T engine to 180 HP @ 7200 rpm (or whatever the exact S specs are), I believe the question was how to get the T engine to S specs. For that you need S parts or equivalent, yah?

Sherwood

jluetjen · jluetjen's Garage

Which T are you talking about? 2.0? 2.2? 2.4TE or 73.5 2.4TK?

Tim Walsh · Tim Walsh's Garage

Snowman,
Contrary to popular belive the noncounterweighted T crank is forged and is actually preffered by racers for it's light weight. The crank would be just fine. THe rods would have to be shot peened and balanced but from what I've read nitriting isn't necacary for a street engine. The pistons would definitly have to be changed one way or another since there's no way to clear an S cam. The cast iron cylinders would be iffy but I would think with proper oil cooling they'd be ok.

Heads though are an entirely different story. if this engine is a 2.0 then the valves are smaller than the S and the ports are smaller. The 2.2 and 2.4's ports are also much smaller but the valve sizes are just the same.

snowman · 10-28-2003, 11:50 PM

I am talking about the 2.2T as it seems to be the most prevalent.

I am suprized that the T crank is forged. All the referances I have found say it is cast. It may well be strong enough anyway as the power in the most far out engines is still relative low, ie less than 400hp.