Originally Posted by 14 apache (Post 4412611)

Worked on a 557 with 10/71 intercooled 10lbs 0f boost and a hydraulic cam made 850hp this was a ex 900sc. Thought it was lame. If it was mine it would of had a solid roller back in it.

Originally Posted by mike tkach (Post 4412618)

i 100% like a solid roller over a hyd but for some applications [like mine]the headers need to be removed to access the valve covers so more work than it is worth.

Originally Posted by MILD THUNDER (Post 4412523)

I think you have that backwards scott. A roots moves air and does not compress it within the case, where as a whipple does compress it .

I belive a screw has less drag due to the much finer tolerances and no contact of rotor stripping , etc .

Originally Posted by mike tkach (Post 4412483)

another factor is the more boost the harder the charger needs to work,that means the charger eats more power as boost goes up.smitty,i remember a post that said you were really over driving the 3sc.did you have issues with the drive belt slipping.reason i am asking is i have a 565 with a 3sc going to the dyno soon.

Originally Posted by MILD THUNDER (Post 4412506)

My guess, would be somewhere in the area of 50-100hp, on something like we have.

A 500HP engine, with 14.7lbs of boost, should theoretically make 1000HP, or double its power. And engine with 7lbs of boost, should gain 50%. So a 500HP, engine , should make 750HP . , with no parasitic losses.

My engine made 800HP with 7lbs of boost, and a roots blower. If the parasitic loss was 150hp, that would mean 950hp without the parasitic loss. With 7lbs of boost, that would mean my engine, n/a , would be making around 635hp. A 468 with dart heads, 9:1, and a 236/245 hyd roller, isn't gonna make 635HP at 6000. My guess would be somewhere around 550-575HP at 6000. That would put me at 850HP theoretical, and 800HP at the flywheel, so say 50HP loss to drive the blower.

50hp makes sense to me. I can't see my little crappy 10 rib drive belt, lasting very long if it had to turn a load of 150HP.

Most roots blowers have big cog tooth belts. Lots of marine guys run a 16 rib belt to drive their 871, 1071, etc. It works for that. I would not try running a 16 rib serpentine belt, in a blown alcohol engine, making 30 plus pounds of boost, because at that level, you need the big cog belt to drive the blower, as its taking a lot more HP than it is at say, 7lbs.

Heres a comparison of a centrifugal vs roots on Vortech's website. They are showing a "best selling roots', whatever that is, to be consumimg 69hp, while their centrifugal is consuming 48hp. About a 20hp difference. I'm guessing thats a pump gas low boost comparision.

Originally Posted by articfriends (Post 4412685)

Depends on how much boost your trying to make, a m3sc is getting small on even a 540, a 565 even worse, a 12 rib drive gave me 8 to 10 psi w no slip, going to 14 psi and turning it 60,000 created all kinds of slip issues, what kinda boost are you thinking? I was using the mpi 502 brackets which bent and flexed, had to weld strong backs to bracket to get it tight enough to not slip, a 4"upper pulley gave 10 psi on.my 540 and slip wasnt a big issue, a 3.85 gave 12 to 13 psi and had to be real tight which wore out tensioner fast, the 3.70 had to be stupid tight to work. I was building a extra idler to help wrap belt better w 3.70 when i bought my 33avs and put blown 540 off to the side for now