seattle951

I put an offer in on a 1989 2.7L 944 that needs an engine rebuild. If my offer is accepted, I was considering having the motor rebuilt with the following modifications:

- Lighten, cross drill and knife edge crank
- Mild port and polish head and intake manifold
- Increase compression from 10.9 to 11.5 to 1 (custom pistons)
- Replace the catalytic converter with high flow unit

Everything else stays the same. Any ideas on what type of performance increase would come from these modifications? I want the car to be as reliable as the day it came from the factory and just as driveable. Is there anything else I should be consideirng?

Matt O.

if i remember correctly, you can put the a 968 crank in the 2.7 and should see some nice gains, but it's been a while and i could be wrong.

Tom M'Guinn

You'd need different pistons since they would otherwise raise up beyond the deck. But, you could make it a virtual S2 motor with 3L crank, and S2 pistons and head. The orginial 2.7 head is much sought-after by the 3L turbo crowd, so you could sell that to recoup some of the cost...

FRporscheman

No no, Tom is completely off-base here. The 2.7 head is worthless.

Actually the best performance mod is to just swap in a 951 motor and give me the 2.7 motor.

OK seriously. If you want to pump some power out, you can stroke it with S2 crank (~$1000) and pistons ($?) to up the displacement to 3.0L. However S2 pistons with the 2.7 head will yield just less then 9:1 compression, which is less than the early USA NA! Low power. Maybe instead of buying S2 pistons, you can buy custom short rods and keep your 2.7 pistons, so you have higher compression and make better power.

Add an S2 head ($2500?) to make an S2 replica motor.

Or instead of using the S2 head, just keep the 2.7 head and slap a turbo on dat thang, and make yourself a nice 3.0L turbo.

Tom M'Guinn

This motor started life as an 89 2.7.... if you're kick'n ideas around...

seattle951

I am not looking to make big horsepower. I am looking for 15% above stock without sacraficing reliability or driveability. Since I will need to have the motor rebuilt anyway, I am looking for mild upgrades only. Any opinions about if the upgrades I suggested would raise HP from 162 to 185?

FRporscheman

Lightweight flywheel, chip, and exhaust. You might make it to 180 if the engine is running right. A friend has an '89 2.7 with a lightened flywheel, poorly tuned piggyback EMS, light pulleys, 3" catback... it doesn't feel like it has more than 170 hp (crank).

For a better jump in power... If you use just a S2 head with thick headgasket, you'd easily reach 185 or more. Might be pricey for everything needed though.

944CS

no need for custom pistons if 15% increase is all you want

all the 944 cars have cams that are optimized for street driving - peak torque occurs at a low 3 grand for the 8 valve 2.5L cars. The 2.7 has different timing, but I'm sure its still geared for low end torque. If you want 15% more power (186bhp) then you are going to have to address the cam, so the engine breaths better at higher rpms (6-7K). You won't get there with the stock cam.

V2Rocket

so what about the 2.7 engine is different from a 2.5 or 3.0 engine? how did they change displacement?

seattle951

Same crank as the 2.5L but bored to 104mm instead of 100mm. 3.0Ls also have the same bore.

Changes made from 1988 to 1989 in a 944

- Compression raised from 10.2 to 10.9
- Bore increased from 100mm to 104mm
- Larger intake valves
- More aggressive camshaft
- Anti-knock sensor added
- DME upgraded
- Fuel pressure increased
- Higher volume fuel pump
- New catalyst system

Tom M'Guinn

They used the 78.9mm crank from the 2.5L motors with the 104mm bore from the 3L motors, with a one-year-only 8 valve head.

seattle951

If I were looking for serious upgrade, I would purchase an S2 or a second turbo. It would be a lot less expensive than upgrading the 2.7L and provide a better balanced and more reliable car.

This project is about building a car for my wife to drive on DE days (I will have the turbo and my wife dislikes my Mustang GT convertible - Daily driver). I would also like a good car for PCA road trips. My turbo has been modified and is not pleasant on long trips. I considered getting her a Boxer, but it is too small for me to fit in it. I liked the idea of the 2.7L since it is just little different than what everyone else is driving and I still fit in it. Plan B would be to buy an S2, Turbo-S or 968 for her.

V2Rocket

so they bolt a 2.7 head onto a 3.0 block and turbo that?

seattle951

The 2.7L head was reworked (cooling passages) so that it would fit on a 3.0L block. The 2.7L was only available from the factory as a non-turbo.

Tom M'Guinn

Right, preferably with lower compression pistons. Or, as I did, installed a 3L crank and lower compression pistons in an 89 2.7 motor, and turbo that.