2.7 and 2.9 OHV 4 cylinder (Chrysler Aus skunkworks)

[VGJONO]

Hey guys new to all this, but thats not why i am posting this, ive been messing around and making some mitsubishi based engines (4G32, 4G54, 4G63) and ive been having a blast, but then i remembered and old skunk works engine that was made by a few blokes in the Chrysler Australia R & D. Basically they took a 215cui 6 cylinder, lopped 2 cylinders off and made it run, then after an engine failure they bored it out and put pistons out of a 245cui engine in it. sadly the idea was scrapped and no more than that one engine remains. now here is were i got to thinking, it would be cool to have a play around with this idea

History



Lets get to playing around
Sadly i cant exactly copy the engine as the original was not a crossflow designed head, so the power output of this will be slightly higher than that of the original

Standard 2.7L
Bore 95.5mm x Stroke 93.5
Compression ratio 8.0:1


Worked 2.7
Bore 95.5mm x Stroke 93.5
Compression ratio 10.6:1


Now this skunk works engine used the same bore size as the mid sized chrysler hemi 6 engine, so i thought it would have been a common thing to bore the engine out and upgrade to the larger pistons of the 265cui Hemi 6 engine

Worked 2.9
Bore 99.3mm x Stroke 93.5
Compression ratio 10.6:1


Let me know what you think of these, im no pro tuner, just a kid who plays with engines in his back yard, if you see any way to improve upon these, feel free to tell me how

Cheers
VGJONO

[Juno8]

not a bad engine looks good and it does the job

[VGJONO]

Thanks mate, it was something i remembered when i first started messing around with automation, figured it would be fun to try and re-create the engine, although it isnt exact as i cant seem to get 9.5:1 compression without bad engine knock and a massive loss of power, i know with better bottom end parts i can but im trying to keep it correct so i figured i would make the standard one with the cast bottom end just like they would have in the 70's

[Daffyflyer]

Thanks mate, it was something i remembered when i first started messing around with automation, figured it would be fun to try and re-create the engine, although it isnt exact as i cant seem to get 9.5:1 compression without bad engine knock and a massive loss of power, i know with better bottom end parts i can but im trying to keep it correct so i figured i would make the standard one with the cast bottom end just like they would have in the 70's

A better bottom end will only break more slowly due to knock, it won't stop it knocking. Try running a bit less ignition timing and richer fuel mixture

[VGJONO]

Cheers for the tip mate, internals and tuning are new to me. after a bit of tweaking the standard motor is now more period correct, a little bit less power but then again anything over 80kw out of a 4cyl factory motor is good for the mid to late 70's