Hypothetical 383in SBC engine....
07-02-2002, 08:01 AM
#1
Gold Member
Gold MemberThread Starter
Hypothetical 383in SBC engine....
Not really hypothetical, this engine exists it's just not mine.
Would this combination make a good motor for my 3500lbs Formula F206?
What would be the max RPM range?
GM 383 crate engine
Compression...9.1:1
Heads...Stock Vortec iron with 1.94/1.50 valves
Rockers...GM roller 1.6
Cam...GM Hot Cam P/N 24502586
Duration 218/228
Lift .525/.525 w/1.6 rocker
Lobe separation 112
Intake...Edelbrock Performer RPM Air Gap
Carb...750 Holley
Ignition...stock HEI
Dyno test
RPM TQ HP
2500 412 196
2600 419 207
2700 425 218
2800 434 231
2900 442 244
3000 448 256
3100 425 266
3200 455 277
3300 460 289
3400 464 300
3500 466 310
3600 466 319
3700 465 327
3800 464 336
3900 462 343
4000 462 352
4100 463 362
4200 462 369
4300 459 376
4400 456 382
4500 453 388
4600 449 394
4700 446 399
4800 441 403
4900 436 406
5000 429 409
5100 423 411
5200 417 413
5300 410 414
5400 402 413
5500 396 415
5600 390 416
5700 376 409
Would this combination make a good motor for my 3500lbs Formula F206?
What would be the max RPM range?
GM 383 crate engine
Compression...9.1:1
Heads...Stock Vortec iron with 1.94/1.50 valves
Rockers...GM roller 1.6
Cam...GM Hot Cam P/N 24502586
Duration 218/228
Lift .525/.525 w/1.6 rocker
Lobe separation 112
Intake...Edelbrock Performer RPM Air Gap
Carb...750 Holley
Ignition...stock HEI
Dyno test
RPM TQ HP
2500 412 196
2600 419 207
2700 425 218
2800 434 231
2900 442 244
3000 448 256
3100 425 266
3200 455 277
3300 460 289
3400 464 300
3500 466 310
3600 466 319
3700 465 327
3800 464 336
3900 462 343
4000 462 352
4100 463 362
4200 462 369
4300 459 376
4400 456 382
4500 453 388
4600 449 394
4700 446 399
4800 441 403
4900 436 406
5000 429 409
5100 423 411
5200 417 413
5300 410 414
5400 402 413
5500 396 415
5600 390 416
5700 376 409
07-02-2002, 11:59 AM
#2
Guest
Posts: n/a
Is that the 'LT4' hot cam? It seems to have a nice powerband! But maybe look at something with a slightly larger LSA, or maybe just something that isn't cut with a built in degreed baseline..
But dayum thats some nice numbers... IMHO 450ft-lb and 416hph from a 383 with only 9:1...
--Adam (who would love a motor like that in hihs car, although prolly rather have bigger heads and a CC 304 cam
But dayum thats some nice numbers... IMHO 450ft-lb and 416hph from a 383 with only 9:1...
--Adam (who would love a motor like that in hihs car, although prolly rather have bigger heads and a CC 304 cam
07-02-2002, 12:18 PM
#3
Gold Member
Gold MemberThread Starter
This same engine but with a Comp Cams XE282 HR and matching springs (230/236 dur, .544/555 lift (1.6 rocker) with a 110 LSA) pumped out 473 lbs/TQ at 4400 and 446 hp at 5400.
I thought this combo had a torque peak at too high an rpm for a boat. The other set up would be better.
You are right it is the LT-4 cam.
I thought this combo had a torque peak at too high an rpm for a boat. The other set up would be better.
You are right it is the LT-4 cam.
From GM Performance
Hydraulic Roller (LT4 Hot Cam)
This hydraulic roller cam is for service only for all V8 engines with roller camshafts. The duration at lash point in degrees (intake/exhaust) is 279/287; duration at .050" tappet lift (intake/exhaust) is 218/228; and maximum lift with 1.6 rocker ratio (intake/exhaust) is 525/525. Valve lash is zero/zero and lobe centerline is 112 degrees.
Technical Notes: The LT4 camshaft P/N 24502586 was designed to be used in a number of different engines. Therefore, the following change may need to be made to allow for correct assembly of the engine: For LT1 and L98 engines 1995 and before, the dowel pin in the end of the camshaft must be pushed in so extension from end of cam is .30+/-.01", the same as the production part. For 1996 LT1 and LT4 engines, the dowel pin is in the correct position, extending .620" from the end of the camshaft. This camshaft has a fuel pump lobe.
Hydraulic Roller (LT4 Hot Cam)
This hydraulic roller cam is for service only for all V8 engines with roller camshafts. The duration at lash point in degrees (intake/exhaust) is 279/287; duration at .050" tappet lift (intake/exhaust) is 218/228; and maximum lift with 1.6 rocker ratio (intake/exhaust) is 525/525. Valve lash is zero/zero and lobe centerline is 112 degrees.
Technical Notes: The LT4 camshaft P/N 24502586 was designed to be used in a number of different engines. Therefore, the following change may need to be made to allow for correct assembly of the engine: For LT1 and L98 engines 1995 and before, the dowel pin in the end of the camshaft must be pushed in so extension from end of cam is .30+/-.01", the same as the production part. For 1996 LT1 and LT4 engines, the dowel pin is in the correct position, extending .620" from the end of the camshaft. This camshaft has a fuel pump lobe.
Last edited by Iggy; 07-02-2002 at 12:24 PM.
07-02-2002, 03:46 PM
#4
Guest
Posts: n/a
Yeah you can handle the tight LSA cuz you don't need idle vacuum, but a tighter LSA means a narrower torque band...
Is there something similar with like a 114? Either that or see if you can get then to dyno it with big rockers on the intake, but 1.5's on the exhaust, that might get you some more torque
--Adam
Is there something similar with like a 114? Either that or see if you can get then to dyno it with big rockers on the intake, but 1.5's on the exhaust, that might get you some more torque
--Adam
07-02-2002, 03:52 PM
#5
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Posts: n/a
Arg, ok now I'd love for one of the real marine engine guys to jump in here, cuz I really have no marine engine building experience (even bench building
But an LT4HOT on a 383 is a pretty mild cam, look for something with bigger duration, and keep in mind that you don't want a massive exhaust duration I wouldnt think.
That HOT cam installed 'straight up' [which IIRC is 5 deg advanced in the grind] will make the motor idle without any real lope... On a 350, it lopes a bit however.
Keep in mind also that you will quickly run out of heads, so perhaps the best thing to do would be call comp cams and discuss it with them. You probably need to be moreconcerned with the profile around the center of the valve lift, cuz I don't think you'll be able to flow much more than that. I might even say use a large duration but lower lift cam...
Again YMMV, and I may be on crack here, it wouldnt be the first time.. hehe
Ciao
--Adam
But an LT4HOT on a 383 is a pretty mild cam, look for something with bigger duration, and keep in mind that you don't want a massive exhaust duration I wouldnt think.
That HOT cam installed 'straight up' [which IIRC is 5 deg advanced in the grind] will make the motor idle without any real lope... On a 350, it lopes a bit however.
Keep in mind also that you will quickly run out of heads, so perhaps the best thing to do would be call comp cams and discuss it with them. You probably need to be moreconcerned with the profile around the center of the valve lift, cuz I don't think you'll be able to flow much more than that. I might even say use a large duration but lower lift cam...
Again YMMV, and I may be on crack here, it wouldnt be the first time.. hehe
Ciao
--Adam
