Originally Posted by 14 apache

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

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

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

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

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

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