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Vortec Engine Help

5K views 30 replies 5 participants last post by  V8 Super Beetle 
#1 ·
Whats good guys? Need your opinions and advice
Ok here it goes, just bought a 5.7 Vortec motor today. Im thinking of removing a sbc 350 with double hump 291 heads, comp 280h cam, Edel Airgap,holley 750, stock bore with stock dish pistons. out of my el camino. and building up this Vortec, By the way I have a th350 with b&m 2400 stall with 373 gears. Would this be a good idea? I would like to have a nice torquey motor for mostly street that sounds nice and performs great. Would it benefit me at all to build up the vortec motor? If so which mods. The motor was pulled from a wrecked 1998 Chevy 1500. Any and all advice would be appreciated. Thanks
 
#27 ·
Elkyblack said:
Now were these numbers done with the motor now being a 383 or does that even matter?
I presume that is for 350ci, and I think its a hair optimistic.

making it a 383 will make a difference, if you have the crank I would definitely go for it. From a dead stop that thing may end up being a tire burner. :mwink:
 
#28 ·
techinspector1 said:
The nice thing about the DynoSim is that you can change cam timing around and take a look at the results pretty quickly. The XE276 would be a flat tappet grind. The same grind for this motor (roller cam) would be a XR276HR. If we change the seat to seat intake opening from 32 to 36 and the seat to seat intake closing from 64 to 60, we have an intake centerline of 102 instead of 106 and an LSA of 108 instead of 110.
Now, we have these timing figures....
Seat to seat 36/60/75/27
0.050" tappet lift 10/34/49/1
Intake centerline 102
Exhaust centerline 114
Lobe separation angle 108
Seat to seat duration 276/282
0.050" tappet lift duration 224/230
Valve lift 0.502"/0.510"
As turbolover predicted, low rpm torque increases and high rpm hp decreases with the tighter LSA. The break-over point is 4000 rpm. Power builds quickly at the bottom, then peters out past 4000. This grind would make a better daily driver though, in my opinion, than the cam timing I originally used in the DynoSim if you were using a converter that tightened up low enough in the rpm range to take advantage of the torque at low rpm's.
RPM HP TQ
2000 140 367
2500 177 372
3000 226 396
3500 284 426
4000 335 440
4500 380 443
5000 412 433
5500 426 407
6000 418 366
6500 369 298
Peak volumetric efficiency 95.7% @5000
Peak BMEP 188.0 @4500

Here's the first pull to compare....
RPM HP TQ
2000 133 350
2500 169 356
3000 218 381
3500 278 417
4000 334 439
4500 383 450
5000 417 438
5500 441 421
6000 445 390
6500 417 337
Peak volumetric efficiency 99.0% @5000
Peak BMEP 189.5 @4500
Tech, I know this thread is an old one, but I have gotten everything on the list that you mentioned except cam, but was kinda wondering what kind of power could I expect with the roller 283 thumper cam. What are your thoughts on these cams.
 
#29 ·
Elkyblack said:
Tech, I know this thread is an old one, but I have gotten everything on the list that you mentioned except cam, but was kinda wondering what kind of power could I expect with the roller 283 thumper cam. What are your thoughts on these cams.
Thumpr cams are ground for sound, not so much for performance, although it'll perform decent. The cam specs he has listed will produce a lumpy sound. If you want it even choppier, get it ground on a 106 LSA.
 
#31 ·
Elkyblack said:
Are you referring to the xr276hr cam? And how would I get a custom grind?
Yeah. Just call up comp cams and tell them you would like to order a custom grind. The xr276hr ground on a 108 LSA or 106 LSA. The tighter the LSA will have choppier idle and will produce less vacuum. I'm not sure if you're running power accessories. The tighter LSA will also have better bottom end and mid range performance. Top end will suffer as you see in the dyno sims Tech prepared.
 
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