Thread: Blower Expert Needed

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Well if anybody is interested, I changed the pulleys on the blower and you talk about a difference. I start making boost at about 2050, got full 6psi at 2150 and it stays at 5-6 all the way to about 5500rpm and then holds about 6-7 up to 6800 and I let off. This motor is really running now. I have never felt so much power. And I just got rid of a '78 chevy luv stepside with a 383 10.5cr roller comp .630/.630 252in/258ex 106 LSA victor jr intake and the same dart 215cc heads. 10.80s ETs 1/4 @127. This engine feels a lot stronger and definitly more streetable than that 383. I thinks I like it a lot.

W.F.O. Ray

Originally posted by lt1s10
how can overdriving the blower give him more boost, he is down to 1 lb. at top end. if you speed the blower up its just gonna get to 1 lb. quicker. his blower is not big enough. in this case i cant see where speeding up the blower will do anything.

beat the hell out of the air and make alot of heat. if you are looking in to more boost i would get a big blower. the cam i think for this small blower is a bit to big. so is the cid of the engine somthing like 112 500 510 at 0.050. 235./240 this is a howards cam i did build a engine for a guy that had a 177 blower on a 350 he used the BM cam for it the idea is to go past vacuum and go boost . boost is a measured amount of force. the thing that is getting force this fuel /air this make heat and bad thing can happen at wot it would be nice to see say 3to 4 this make having the blower worth be on the car

The 177 blower moves 177 cu. in. of air per revolution. If the engine normally uses less than that amount of air per rev, the blower will make pressure at 1:1. Since 177X2 is 354, a 350 will be marginal at that ratio. A positive displacement blower does NOT compress air, it just moves it. The pressure comes when the engine is not taking the air away as fast as the blower is pushing it in. Nit-picking maybe, but it helps to understand the process.

now someone cane explane how it picked up 5 lb. of boost at 6800, and stayed the same up to 5000 rpm's.

Ray:
Glad it seems to be working out for you, but like Pat said, a bigger blower & maybe a couple of 750 DP's will work less to make the same power (there is a point of diminishing returns by overdriving the blower) I changed from a 15% over driven 6-71 to a 8-71 straight up on my 502 (also changed the cam & went to aluminum heads..mostly for a heat sink) Results: motor made 800 HP & 725 lbs of torque @ 5800 RPM on crapo 91 octane pump gas..with NO detonation. This was an increase of 80 HP and no more screwing with $$$114 octane race gas.

Originally posted by R Pope
The 177 blower moves 177 cu. in. of air per revolution. If the engine normally uses less than that amount of air per rev, the blower will make pressure at 1:1. Since 177X2 is 354, a 350 will be marginal at that ratio. A positive displacement blower does NOT compress air, it just moves it. The pressure comes when the engine is not taking the air away as fast as the blower is pushing it in. Nit-picking maybe, but it helps to understand the process.

you are rigth. BUT there is many variables . a big blower running it not as fast is the way to go . smaller bower will make more Heat . and they eats drive belts at more boost and run them to hard and you will melt down the engine watch out for this

Well, according to Holley/Weiand I am running my blower safe at 1.90:1 over-drive. The 177 is a big block blower and runs at 1.98:1 on a 454 big block to maintain 6psi. The stock pulleys I had were for a 350. I understand that a bigger blower would work less and make more HP, but I don't want a hole in my hood.
The pulley change made the difference I needed. I'm happy.
Holley says it will hold up to that because if you ordered the same set-up out of Jeg's for a big block you would get the same pulley ratio.


It1S10- I NEVER HAD ONLY 1LB BOOST, I ONLY WAS LACKING 1-2PSI FROM HAVING THE 6PSI THAT I WANTED IN THE FIRST PLACE. YOU MISREAD THE ARTICLE SOMEWHERE, PLEASE CHECK BACK AGAIN. MY BOOST WAS FALLING TO ABOUT 4PSI AT HIGHER RPM.

I understand that a bigger blower would work less and make more HP, but I don't want a hole in my hood.

HOOD.. We don't need no stinkin hoods

Originally posted by DynoDon
I understand that a bigger blower would work less and make more HP, but I don't want a hole in my hood.

HOOD.. We don't need no stinkin hoods

yes i hear that. i do not have a hole in my hood they think i have a gear drive

Pat, that is one mighty fine engine you got there.

It1S10- I NEVER HAD ONLY 1LB BOOST, I ONLY WAS LACKING 1-2PSI FROM HAVING THE 6PSI THAT I WANTED IN THE FIRST PLACE. YOU MISREAD THE ARTICLE SOMEWHERE, PLEASE CHECK BACK AGAIN. MY BOOST WAS FALLING TO ABOUT 4PSI AT HIGHER RPM. [/B][/QUOTE]


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you said, holly said........ As long as I don't go into a vacuum at high rpm the blower is working well.

tech said..........So, I assume that if the boost fell to 1 psi at the top, the blower would be doing an exemplary job???? Sounds like lip service to me.

you said........tech, your idea sound more like it. What do you think about me gearing it a little bit more. I only need about 2psi to be optimum at high rpm.

for some reason i read into that you was looking for 2 lbs. of boost at 6000 rpm's.

Originally posted by DennyW
I read it like Mike read it. Frankly, I'm a little confused now. The one thing I'm thinking about, is if you increase the boost, or maintain a 5-7 pounds at the upper rpm's, are you considering the massave load at that rpm's on all moving parts ? Do you have extra parts like the racers that are sponsored does laying in the trailer ? I hope so.

that makes you a dumb a%s like me. used to i couldnt spell, now i cant read.

Originally posted by DennyW
Oh well. I can't hardly wait to see how many runs he gets when he beefs it up.

sounds like he has some good stuff, 6800 is getting a little tight.

Originally posted by DennyW
Oh well. I can't hardly wait to see how many runs he gets when he beefs it up.

Denny, I'm only running 6psi on 9.0:1 Forged Ross Inverted Dome pistons, I got a 4340 Eagle crank, 4340 H-beam Eagle rods completely balanced assembly, competion oil pan with uni-directional windage screen, blue-printed oil pump, solid roller Comp H bar pop-up lifters custom comp cam Iron Eagle 215cc heads with Pro magnum roller rockers and Hi-tech 5/16 push rods

Originally posted by DennyW
Ok, so at 7 pounds boost at that rpm, 13.5 is ok with you ? Just use good fuel of course. And make sure that timing and richness is right.

I am also running a timing retard for every pound of boost my ignition retards 1 degreee. I also blended and polished my combustion chamber to help eliminate hot spots. My boost timing is 32 degrees at full 6 psi boost. I'm running pump gas and haven't seen any problems And I did my homework on my piston selection and block height and headgasket to give me a good quench area. And last of all it is a little rich. If you got any other ideas to keep it out of detonation share em.



Ray