Need help with building a blower rotating assembly...

FuryZ28
09-25-2006, 08:31 AM
I'm looking at putting 16-20 lbs. of boost through my LT1. Will the amount of boost have any bearing on what parts I should buy? I mean, will a forged SCAT or Eagle crankshaft be perfectly fine, or am I looking at going with a more expensive crankshaft? I'm looking to put down 750-800 RWHP, so it's not like I need to build it like I would for a 1200+ HP motor...at least I don't think I need to? Will a generic SBC rods, pistons, & crankshaft w/ 1-piece main seal and such do the trick? I tried looking up these parts on Summit's website, and they say such parts fit Gen-I SBC's, but no mention as to whether it fits Gen-II SBC's. Any brands you'd recommend for my boost goals? Any ones I need to stay away from?? What do I need to look for when purchasing piston rings for my blower setup?

rskrause
09-25-2006, 09:04 AM
800rwhp is a lot. When you account for the drivetrain losses and the internal power consumed by driving the blower it is equivalent to well over 1000hp. When you read what you are likely to see posted here, ask the poster if their car has 800rwhp.

You need very stout parts to make that kind of hp reliably. I can vouch from experience for Callies and Lunati cranks (you can get away with the less expensive Dragonslayer or Sledgehammer lines, they have less machining/lightening but are just as strong), and Lunati or Oliver or Manley rods. The are other good ones, for sure. There are a lot of piston choices depending on the CR you want. Diamond, Probe, JE, Lunati, Ross, etc.

Gen I cranks are for 2-piece rear seal. There are no differences in the rods and pistons.

800rwhp is VERY expensive when you consider the supporting components needed. I suggest a more realistic goal. The magazines and the internet make it seem like everybody has one. They don't. The shop I'm associated with dynos a lot of cars and those with that kind of hp are few and far between. Most run race gas at that power level. I run pump 100 octane unleaded in mine. It will run on 93, but I don't push it when running that swill.

http://www.kennedysdynotune.com/images/dynograph.jpg

Notice the number "252" on that dyno run? That was the number of runs on my car at that time. There were a number of different combos tested, so it's a bit misleading. But the point is that 800rwhp from a pump gas small block is not "plug-n-play". Plan on 8-10 hours of dyno time as part of the cost. The $1,000-1,500 that will run will be a drop in the bucket for this kind of project.

Rich

FuryZ28
09-25-2006, 09:10 AM
Sorry, I screwed up. I meant to say 750-800 HP @ the flywheel...does that change anything?

rskrause
09-25-2006, 09:19 AM
Sorry, I screwed up. I meant to say 750-800 HP @ the flywheel...does that change anything?

You still need top quality pistons. Other than that, you can get away with the stuff most people use.

Rich

FuryZ28
09-25-2006, 09:34 AM
Thanks. Any brands of pistons I need to avoid?

rskrause
09-25-2006, 12:28 PM
You need a top quality forged 2618 alloy piston designed for a "blower" application. This mean that the top ring is lower, allowing a thicker ring land, and a thicker crown. Manufacturers include JE, Ross, Diamond, Probe, and others. Weight is less important in this case than strength, you don't need to spin a blower motor through the roof to make power. But all else being equal, lighter is still better.

Rich