2.7L in 924S DME questions

[The Glademister]

Surprise, surprise! Turns out I've got a M44.11 engine in the '87 924S purchased recently. That's good news as I'm about to start preping the car for autocross. But it has the original 2.5L DME.

So how much of a difference would there be from a 2.5L DME to a 2.7L? Air/fuel mapping?

Can that be corrected with a simple chip change?

If I'm doing that... what if I upgrade injectors and FPR to 3 bar?

Performance modifications planned include exhaust, suspension, lightweight fly wheel and stripping the car down to about 1900 lbs.

[Raceboy]

I think you better want the 2.5 DME as it should have better ignition advance table. I could be wrong though but you could compare yourself.

[The Glademister]

Originally Posted by Raceboy

I think you better want the 2.5 DME as it should have better ignition advance table. I could be wrong though but you could compare yourself.

Is that flashed onto the one chip that can be changed?

[v2rocket_aka944]

SHould be OK with the DME you have, make sure to run premium gas.
1987 would have had the 9.5 CR engine, right? Might have more advance than the 10.9:1 CR 2.7L wants.
Though the engines are so similar that I wouldn't worry too much about it.

[The Glademister]

Originally Posted by v2rocket_aka944

SHould be OK with the DME you have, make sure to run premium gas.
1987 would have had the 9.5 CR engine, right? Might have more advance than the 10.9:1 CR 2.7L wants.
Though the engines are so similar that I wouldn't worry too much about it.

87-88 M44.07-09 2.5L are 10.2:1 CR

89 M44.11-12 2.7L are 10.9:1 CR

[v2rocket_aka944]

Really? The 1987 924S got the HiPo engine before the 944?
Didn't know that.

If so...you should be OK with that DME

[J1NX3D]

IIRC the '86-'87 924S had the detuned engine. Also in '87 the 924S Le Mans/LE had the same tune as the 944. In 1988 all 924S and 8v 944 got the same tune 2.5L for all markets. The US tune just adds confusion for the pre-'88 cars.

I don't know off-hand if pre-'88 US spec 924S were also lower tune than RoW 924S, which were all lower tuner than 944's in their respective market.

[The Glademister]

I think the best course of action is to get a performance DME chip specifically for the 2.7L engine. That, coupled with turbo or 944S injectors and 3 bar FPR should make for really decent HP.

[v2rocket_aka944]

No need to change injectors, or raise FPR.
Stock NA ones are more than capable of supporting the power you are looking at.
Not to mention the 951 injectors are the wrong impedance for your NA DME.

[petrolhead611]

The very last few 924S models, certainly for Germany ,not sure about anywhere else, apparently had the 2.7L engine.

[Rasta Monsta]

No way. Literally.

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[The Glademister]

Originally Posted by Rasta Monsta

No way. Literally.

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Regarding...

The above poster saying very late 924S having 2.7L from the factory?

Or...

My $800 Craigslist 924S having a transplanted 2.7L?

[Rasta Monsta]

The former! As to the latter, there are plenty of interesting things that can find their way into a 924s...

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[v2rocket_aka944]

I did see photos once upon a time of a 924S skinny body with the late 944 interior and 2.7L engine fitted.
Might have been production one-off?
Or maybe a 1989 944 with little fenders fitted

[dgcantrell]

If you look at the option code sticker inside the rear panel behind the carpet just over the spare tire, it will tell you what engine/trans combination came in the car from the factory. Being that 88 was the last year for the 924 series, I don't think they came from the factory with the 2.7's... But I'd take one in heartbeat.. LOL

[J1NX3D]

Originally Posted by v2rocket_aka944

I did see photos once upon a time of a 924S skinny body with the late 944 interior and 2.7L engine fitted.
Might have been production one-off?
Or maybe a 1989 944 with little fenders fitted

those were a limited run of pre-production 924S2's.

[The Glademister]

Photographic proof for any doubters...

[J1NX3D]

Nice! I'd definitely be picking someone did a transplant as no 924S came with the 2.7, especially anything as early as '87. I don't think it would be a 924S2 as those were 16v.
Porsche 924 S2 !

[petrolhead611]

The very few 2.7l engined 924S were sold in early '89. Porsche were probably using up parts they had too many of in a runout model. They also had a rubber? chin spoiler. Or so I read in a German online magazine about watercoolers.
The 924S2 mentioned in the French article were after market conversions using the 944S2 engine and Turbo brakes.

[The Glademister]

Originally Posted by J1NX3D

Nice! I'd definitely be picking someone did a transplant as no 924S came with the 2.7, especially anything as early as '87. I don't think it would be a 924S2 as those were 16v.
Porsche 924 S2 !

Agreed. This car came from a rural area so at some point the timing belt probably broke and the PO bought a salvage yard engine from a '89 944. Backyard mechanic drops it in never even knowing the difference.