Kenne Bell 2.6

[cstavro]

Eatons are really low efficiency - 55%. the m90 is good for 400 bhp, while the m112 is good for about 450 hp. they are designed to run at 12,500 rpm, so changing to a smaller pulley makes them even less efficient. this means that they heat the air more, requiring the added weight and complexity of an intercooler.

kenne bell uses twin screw sc at 90% efficiency, and have lower parasitic loss. i don't see a 'kit' for the 3800 sII, but has anyone tried a 2.1/2.2/2.4 kb? the 2.1h has made 900+ hp on a 4.6 2v ford.

 

[steveX]

This is true.
I had a M90 series III 3800 motor Dyno 425hp (all the goodies) at the wheel with the 4t65-e HD trans (ruin alot of trans before i got it right). Running a 3" pulley on the M90 at 5000 engine rpm will produce 400+ degree of hot air.I use to monitor the blower outlet temp with a AUTOMETER dual channel Air temp sensor ans gause. all air temp test was done with the blower strap to the engine running in a car driving around town. I have try many different ports, not worth the gain when compare to the work involve. Improvement can be made, and if any maybe a 5-10% gain with out a pulley swap. The M90 also eats alot of HP from the crank. a 490hp flywheel/flexplate motor will put about 375-380hp at the wheel/tires. Some of this is also lost in the automatic trans. Spining a M112 just eats more HP and only produce 22 cu-in of more air that the m90. If you do liquid-intercool the M90 you can expect to see a 50% drop in blower outlet temp. Add a ice box/moroso in-line with the flowing liquid and you can see a 70-80% drop. the is more likly for the track.

When the m90 is intercool. the blower outlet temp will change. the lowest i have ever gotten a liquid intercool m90 with ice was 125 degree temp at the outlet winging the motor at 5000rpm, t-stat and fan at 160 degree. Since the blower temp goes from 400 degrees to 125 degrees when intercool the fuel curve will also change and you can put more timing into the motor, so all you hp is not comming from boost. the additional fuel and tighter timming will add up in hp. this will be notice in the exhaust sound.

The M90 is still a good quality/durable engine air pump for street application. I have seen 100,000 mile with no problem, with service and oil change this blower will perform like OEM like the engine.The trans is knowen for broken diff, chain, input shaft, anything else is normal due to torque over-load.

The twin-screw is owen by a company in germany. I believe whipple is the U.S. distrubutor for twin-screw (lycos) blower. Thes blower make boost like a turbo, but the boost comes in very early. most of the time you will see maximun boost at 2500 engine rpm with the twin-screw blower. This early boost shock can hurt and damage driveline parts. Don`t get me wrong, this is the blower of performance, and so should be everything else behine it, or you will twist crankshaft, blow trans (normal), damage axle. the blower is too serious for a gasoline engine air pump, maybe if we run NITO or METHNOL. A true winner in races the twin screw...I believe NHRA is now runing twin-screw in most top-fuel dragster and funny-car.

 

[cstavro]

thanks steve. 400F is insane! using an intercooler to pull that much heat is just a bandaid for a really inefficient blower. screw sc also take a fraction of the hp (vs roots) to spin.

screw sc make massive, instant torque. our tiny ports compound this problem. that's why i still prefer turbos - you can put the boost anywhere you like. dbb garretts supposedly make the engine feel like a larger engine - instant response and very progressive. i wish i had money!

 

[jdredd]

I wouldnt consider an intercooler a bandaid.. is it the same rule when applied to a turbo intercooled setup?

 

[cstavro]

a turbo has 75+% adiabatic efficiency. an eaton is 55% at BEST at stock boost. putting a smaller pulley drops that efficiency significantly...to the point where you're heating the air *more* than you're pushing it. while a turbo may increase air temp 150F, the eaton which steve mentions raised it ~400F. so using an intercooler to reduce temps 150F is fine (and the turbo is still pushing air), but cooling the extra 250F is the bandaid...it's trying to compensate for a really inefficient blower.

the stock eaton is meant to run 12,500 rpm (peak efficiency) at ~5000 engine rpm, then running the eaton 25% faster (a 3.0" pulley) will give peak sc efficiency at 4000 rpm. above that, the eaton doesn't push air well. this explains why heavily modded m90 cars have massive torque at 3000 rpm, and the hp curve is flat (and not rising). an eaton is fine for oem. you can't trade torque for hp with the eaton. it's not meant to push air at high rpm, and smaller pulleys does the exact opposite.

 

[jdredd]

i understand how turbo's and eatons work.. my gripe was the term bandaid..

Its the same way where a highpower v8 guy may say a less cyl motor needs a turbo or blower as a bandaid for not being a v8.. get my drift?

i am with you guys, that a turbo is really the best thing if your gonna be racing. Tho Jonbobs Whipple 3800 is nice. Just have to keep a tranny together to get a full run..

 

[cstavro]

i see where you're coming from. those v8 guys are being snobbish. there was a time when 274ci buick stage 2 race cars whooped the 310ci v8 in busch grand national! people went to great lengths to prove that the stage 2 couldn't make that power. the fact is, all things being equal, a v6 makes more power per cylinder than a v8.

chevy has historically had the worst intake ports. they've had to go to canted valves against dodge's w9 heads (inline valves and siamesed ports like the gen 1 chevy). i'd consider that a bandaid for poor head design.

i wouldn't even consider a turbo a 'bandaid' for our terrible cylinder heads. we're making more hp and torque than many v8 twice our displacement. boost is an equalizer - it makes our heads perform like better flowing heads. our intake valves are still on the small side though. if we were valved the way the LS3 is, we'd have 2.0" x 1.50" valves...with flow approaching 300 cfm (ported).