seattle951

I have an opportunity to pick up a very clean 1988 924S (160 hp) with a broken timing belt for $1200. I have found a 1989 944 2.7L with an automatic with a tired interior and faded paint.

How hard would it be to:

- Rebuild the 2.7L
- Add a peformance chip
- Install the 2.7L in the 924S without further modfication

Do I need to swap out the DMEs?

The 2.7L has 5 additional HP and about 15 ft-lbs of TQ compared to the 924S motor. The chip would add about the same.

The 924S is lighter than the 944 and I would remove the AC. Any thoughts on what the 924S performance would be like?

I had a 1987 924S (150 hp) and it was adequate. This configuration would add 20 hp over the 87 and about 40 ft-lbs of TQ. By shedding the AC (75 lbs?") and increasing hp/tq by 20% should put the 924S in its sweet spot.

Any thoughts?

V2Rocket

Assuming your 924S is a manual, you would need to get a DME from a manual car along with a flywheel, clutch and pressure plate setup that would fit the 2.7.

IMO a 2.7 wouldn't really be worth the trouble in swapping as the gains are minimal. However if you can spare another $1500 or so, during the rebuild of the 2.7 you could swap in the crank, computer and some other stuff from an S2 and make it a 3L 8v car which would give it a nice low end.

But by then you might as well turbo it.....

knfeparty

I guess it matters how much stuff you can use from the 88 motor.

I think the DMEs are the same except for the chip that is in them. So you can yank the chip out of the 89, or you could just buy an aftermarket chip.

It would be nice to be able to reuse the clutch and all from the 924s.

seattle951

I am guessing the performance increase would be significant.

1987 924S
- 150 hp
- 140 ft-lbs
- 2765 lbs
- 18.4 lbs/hp

1988 924S
- 160 hp
- 155 ft-lbs
- 2641 lbs
- 16.5 lbs/hp

1989 944
- 165 hp
- 166 ft-lbs
- 2844 lbs
- 17.3 lbs/hp

1988 924S hybrid
- 170 hp
- 180 ft-lbs
- 2566 lbs
- 15 lbs/hp

That would be about 22% improvement in the power/weight ratio compared to the 1987 924S that I had before.

V2Rocket

What type of chip would you use? I just sold an Autothority chip for 85.5-87 cars that claimed a 14HP gain and I imagine it would work similarly on a 89 car also, although new chips from them are around $400. You'd have to be somewhat cautious though with that engine because the chips basically make more power by advancing the spark more than the stock chip, especially in the higher RPMs. The 1989 car was high compression stock, and with a high CR and lots of spark advance you'd want to run nothing less than premium fuel (which you would prefer to anyways with the chip). I would be impressed if you could pull off 180 ft/lbs though.

PorscheDoc

You won't get anywhere near 75lbs out of the ac delete. Maybe 40-45 if you are lucky.

seattle951

ProMax claims their chips add 12 hp and 15 tq to a 2.7L. Lindsey Racing sells a chip for $200 but does not provide any hp/tq metrics.

Assuming this is accurate (big if), the hybrid would have:

- 177 hp
- 181 ft-lbs
- 2526 lbs (less 40lbs for the AC per Doc)
- 14.3 lbs/hp

14.3 is a big improvement over 18.4. I already have a 320 RWHP 951. I would be happy if this car was a reliable and well balanced daily driver. I actually enjoyed my stock 924S over my 951 as a daily driver. To get the performance out of the 951 I made too many sacrafices in drivability, balance and reliability.

ritzblitz

968 motor would be badass

seattle951

There are a few of those in Seattle. However, that is overkill and I am not willing to take the drivability hit by creating a "Frankenstein". If I want to go that fast, I would drive my modified 951 and put up with its quirks, bad manners and poor gas miledge.

V2Rocket

If anything, a 968 motor will be more "driveable" than a 2.7 because the larger displacement and resonance intake help it make lots of torque

seattle951

I am familar with one of the 968/924S hybrids in town. It is a money pit with owner constantly trying to get the bugs out. The 968 motor has more power than the rest of the components in the car were designed to handle.

When I say drivability, I mean "turn the key" and it runs. When it runs everything remains in balance (handling, braking, driving comfort, interior noise, ect). The 2.7L is such a close match to all the original equipment that the natural balance of the car should not be impacted. It should be as reliable, comfortable and predictable as any stock 1988 924S.

blown 944

IMO a better idea would be to use a 3.0 crank in the existing 924s engine. Even using the shorter rods (rod ratio is still good at 1.7) the engine would have far more torque and would be a great dd. You should be able to do it for ~ 2.5k.

The 2.7 is all bore so until you are in the upper rpms it isn't going to feel much different IMO

why is your mileage bad with the 951, and did you ever change the intake??

seattle951

How would the DME and chip be handled? A stroker would require a lot more fuel? Would stock injectors be sufficient? I would like to keep things simple and not get into a long troubleshooting process and end up with a car that is unreliable or twitchy. Is there an easy way to approach this? Has it been done before?

The only time the 951 leaves the garage is to give it a workout. I only go out in good weather and have a favorite set of roads with no traffic where I push the car. I have been getting about 12 miles per gallon on these runs. I get about 8 to 10 miles per gallon at DE days. The miledge would probably be a lot better as a DD driver.

I have been crazy busy lately and spending most of my time travelling. I have not had any time for the 951 or to install my mods. Reading another post gave me an ideas that my LR dual port wastegate may be part of my problem. I have a new Tial on the shelf. I plan to install that first and then re-benchmark. If there is no noticable difference, I plan to compare the LR manifold directly to the stock manifold. I am still very skeptical of the LR manifold based on testimonials from other vendors, some of the automotive engineers (consultants) that work on my team, and the research I have done. The only way to settle this is to test the manifolds side-by-side with all other variables unchanged. I will probably get to this in a few months if I don't get the desired results from the wastegate swap.

fast951

Going from a 2.5L to a 2.7L you will see some gain, but nothing to justify the cost. Racers do it because it's legal in their class and they are after every HP. For a street car, this will not be the case.

If you decide to go the 2.7L route, it bolts up. For engine management you just need a chip, you can use the existing 2.5L DME. The engine rebuild will cost the same as any rebuild $$$$.

A better option will be to install a 944S engine or the 3L 16V. You will gain more power across the board with not much more money. Find a clean running engine + DME and the cost will be less than purchasing and rebuilding a 2.7L.

If you are getting a good deal on the 89 2.7L engine, you can always part it and help offset the cost of the project.

seattle951

I can get the 1989 944 Automatic for less than $2k. It has had a hard life but the owner still drives it to work every day.

I don't do any of my work myself and have no interest in parting myself. I was considering offering the 1989 to my mechanic less the motor in exchange for some of his time to rebuild the 2.7L motor.

Maybe the better choice is just to rebuild the stock 2.5L and stick with the 160 hp. I don't want a car that is pieced together and unreliable or unbalanced. As mentioned, I have been following the local 924S/968 hybrid and I don't want the hassles of something like that. My 951 with its loud (no soundproofing), truck like ride (aftermarket suspension), unstable nature (I need to turn down the boost or get some professional driving instruction) and constant need to fiddle and adjust thing is more than I want in another Porsche. I want to turn the key and just have it run.

Thanks for the input.