My 383 rwhp estimate?
09-11-2013, 08:41 AM
#1
My 383 rwhp estimate? Im currently putting my engine back together. Im really excited to know my hp before I take it to the dyno shop. Here are my list of mods: Pacesetter LT's, 3" exhaust, CC280XFI, TFS195cc ported heads, cc1.6 rr, beehive valve springs, bored .030 over, scat forged crank, scat 6" H-beam rods, mahle dished -16cc pistons. Obviously this is before a tune. I tried to get quality parts (even though I know I should have went with AFR heads! 
)and taking you guys in this forums advice. Let me know in your honest opinion what would you have done differently to squeeze out more hp? IM not an expert but I think I did adequate enough research! Thanks for your input!
)and taking you guys in this forums advice. Let me know in your honest opinion what would you have done differently to squeeze out more hp? IM not an expert but I think I did adequate enough research! Thanks for your input! 
09-11-2013, 08:57 AM
#2
The low compression heads are going to kill your horsepower. Why did you choose the parts you did? With a .028" head gasket and .020" in the hole your compression is down around 9.5:1. That is HORRID for N/A, unless you are planning boost?
I would have gone with a flat top piston, reputable mail-order tune, reputable ported stock castings by AI and a custom grind cam. Assuming a good tune you could reasonably expect 420+whp (my combo puts down 450+whp and uses those parts). In current trim though I would guess you'd be somewhere around the 340-360whp range.
I would have gone with a flat top piston, reputable mail-order tune, reputable ported stock castings by AI and a custom grind cam. Assuming a good tune you could reasonably expect 420+whp (my combo puts down 450+whp and uses those parts). In current trim though I would guess you'd be somewhere around the 340-360whp range.
09-11-2013, 09:19 AM
#3
F*******!
09-11-2013, 09:29 AM
#4
Village Troll 
iTrader: (2)
My machinist suggested to go dish because of the drivability on the street. He also said those pistons to keep from burning race fuel. With 55cc heads we sat their and did the math. We came up with around 10:4 cr with those pistons and 9cc head gaskets. I wanted to be around 11 cr but he said I would need race fuel. If my cr is in the 9s, Then I need to return the pistons like TODAY! I wanted flat top pistons initially anyway. Should have went with my first mind!!!! F*******!
F*******!This is why it is so important to do research into machine shops before giving them a block.
09-11-2013, 10:09 AM
#5
In other words, he had no idea about the LT1 reverse cooling and knock sensor features. The math is wrong somewhere. I am running 58cc combustion chambers, .040 gasket, zero decked block, -12cc pistons and I'm at 11.0:1 with a 396. Sorry to say, but your compression is going to kill any potential power you have.
This is why it is so important to do research into machine shops before giving them a block.
This is why it is so important to do research into machine shops before giving them a block.
09-11-2013, 11:22 AM
#7
I mean the guy has built a decent amount of promod big cube engines. He is the best around the area. I guess???? LOL! But which piston would you suggest if you could help me out to keep from burning race fuel. I just want to be able to run premium. This is the info that I really need to know! I have a zero decked block!
Get the fear of needing race gas out of your head - LT1s cool the cylinder head before the block unlike standard SBCs, so can run a lot more compression. Bone stock CR is ~10.4:1 - quite a bit higher then what you have. With the proper tune people are running 12.5:1 on plain old 93 pump gas. I would shoot for between 11.5:1 and 12:1 for an NA build just to leave some room for error in tuning if you are using a mail order tuner. If you know your tuner is good, 12.5:1 is OK.
I would look at flat top pistons with 5cc valve notches like the SRPs.
If it was an old iron headed ~8.5:1 SBC, then the machinist would be valid in his concern. Tell him you want flat tops and at least 11.5:1 CR, and if he still is hesitant or makes a big deal out of it then go somewhere else.
Trending Topics
09-11-2013, 11:23 AM
#8
I mean the guy has built a decent amount of promod big cube engines. He is the best around the area. I guess???? LOL! But which piston would you suggest if you could help me out to keep from burning race fuel. I just want to be able to run premium. This is the info that I really need to know! I have a zero decked block!
The STOCK LT1 is 10.5:1 compression and you are MUCH lower than that. Your machinist I am sure is good but it is obvious he has never built a (quality) LT1 before. Performance LT1s run well over 11:1 compression (mine is just over 12.5:1) and run on 93 octane just fine. Reverse flow heads allow MUCH more advance and permit higher compression without detonation. A good cooling system and a good tune are all you really need to keep detonation in check. Realistically you should have gone with a different just-about-everything.
09-11-2013, 11:39 AM
#9
TECH Regular
That means nothing in the LT1 world. I can't count the number of lackluster LTx motors I've seen that were built by someone who "really knew their stuff" or "has been building race motors for 30 years". I'm talking about stroker motors that ran no faster than my stock engine did with nothing more than bolt-ons and a decent cam.
Find a machinist who has a LOT of experience with LT motors, or do your homework on here, spec your own combo, and ignore whatever conventional SBC-rooted advice your machinist tries to sell you on.
A hot NA pump gas LTx has a compression ratio of 11.5 or higher.
Find a machinist who has a LOT of experience with LT motors, or do your homework on here, spec your own combo, and ignore whatever conventional SBC-rooted advice your machinist tries to sell you on.
A hot NA pump gas LTx has a compression ratio of 11.5 or higher.
09-11-2013, 05:45 PM
#13
Most heads/cam setups on a stock shortblock are 11.2 or so.
In the first post it sounds like you want to to run it BEFORE tuning it?
Don't even start it without a mailorder tune, about the best case scenario for starting a built stroker on stock tune is glazing the cylinders and never having the rings seal right, worst case you can ruin the engine before it leaves the garage.
As was already said you did research but found a lot of BAD info unfortunately this sort of thing is real common
In the first post it sounds like you want to to run it BEFORE tuning it?
Obviously this is before a tune.
Don't even start it without a mailorder tune, about the best case scenario for starting a built stroker on stock tune is glazing the cylinders and never having the rings seal right, worst case you can ruin the engine before it leaves the garage.
As was already said you did research but found a lot of BAD info unfortunately this sort of thing is real common
09-11-2013, 05:53 PM
#16
I guess this is why he suggested pistons that gave me extremely low CR. I was planning on building a turbo platform, but the way things seem now is that's the specs my machinist gave me. Now im to the point where I want challenge his knowledge. . . . . . . The only way I see the reason for the 16cc dished pistons is because of the 55cc of the heads. SMH . . . . feel like im screwed now. I guess im learning; the expensive way!
09-11-2013, 08:23 PM
#20
Yes LTx can push over 12.x:1 on pump gas.
The only way you will make power now is as stated with a turbo or a supercharger.
I'm going to guess that without it you're going to be around a mild bolt on stock engine.
The only way you will make power now is as stated with a turbo or a supercharger.
I'm going to guess that without it you're going to be around a mild bolt on stock engine.
