klumb15

anybody have any experience with these things...i know they are the smallest of the bunch, but I hear they make a huge difference....can I run one of these things on my L98 heads, or are they a differnet angle or something??? also I need to know stuff like how big of carb, how much power increase I'll see, and any input you have, feel free to post...thanks

97WS6SCharged

Holley/Weiand makes a 142 Pro-Street setup for serpentine cars. the PN is 6504-1 for satin, and 6509-1 for polished. You may have to elongate the 4 center holes for 87+ heads. They claim a 25-40% increase in power and torque. As for the carb, I'd discuss it with a Holley tech, but they'll probably tell you a 750 double pumper with mechanical secondaries.

klumb15

what if i convert to older heads...because i've asked some people, and they said i should switch my heads anyways cuz my compression way too high...so i thought if i went with an older head, and one with a bigger bowls, so that would bring my compression down, and i would have the right bolt holes, so i would kill two birds with one stone....but the thing is i dunno which heads to get...do they make special heads designed for this, or is there heads for like a 400 SB that have bigger combustion chambers or something..what do you guys recommend??

Chris9450

I can't think of any head numbers offhand, but if you get heads with something like 62cc+ chambers and/or a thicker head gasket it'll drop your compression down enough to use a supercharger. If I'm remembering correctly most supercharged engines want about 8-8.5:1 compression before supercharging.

97WS6SCharged

You didn't say whether you were using the iron L98 heads or the aluminum L98 Vette heads. I'll assume iron since that's what came on the majority of L98 engines.

That said, you aren't going to find many older iron heads that flow as good as the L98s. They were around 64 ccs from the factory, and compression was around 9.1:1 I believe. The heads aren't really what's holding you back on the roots blower, it's the belt system. Most of the roots style blowers are setup for traditional V belt motors. I'd keep the L98 heads and just wallow out the bolt holes in the intake manifold, that's alot easier than swapping heads. If you really want to drop the compression and run alot of boost, look into changing the pistons to a forged, low compression design.

angel71rs

The L98's don't flow much different than old 76cc 1.94 heads. You can compare flow #'s of aluminum L98's and 76cc 882 & 441 heads on hiperfchevy's head flow database:

http://chevyhiperformance.com/techarticles/41598/

If you do go with 76cc heads, make sure and avoid the crack prone late 70's versions. The earlier heads will have the bottom edge of the heads, where the lower row of head bolt holes are, be pretty much a straight line. Lightweight castings will have the bottom edge scalloped around the bolt holes.

klumb15

well actually they are the aluminum L98's.....i gotta keep my eye on my money situation, the funds are diminishing fast...thanks for the help tho...

S. Holley

It is not necessary to lower your comprssion ratio... this is a street motor and the blower will make 4-5 lbs of boost. That is not alot... if you go with larger chambers you will need to run MORE BOOST on your car. Most guy who are running low compression are putting out more than 9 lbs for boost... some up to 12-13 lbs. LOw compression allows you to runnn more boost....

look at the LT1 camaro that is a high compression engine... they run from 6-8 lbs with stock motors... making 10. to 1 compression...way more than your L98.

ALSO aluminum heads allow you to get away with slightly more compression than IRON... also a awesome ignition system helps.

If it were me I would just run the blower as is... with a stock L98 long block making about 210-220 rwhp... the mini blower should put you up to 275-285 rwhp... that is close to the LS1 :-)

klumb15

so i could run it on my stock vette motor, and just upgrade the ingnition to like a 6 MSD unit, and I should be alright??

klumb15

would I gain alot more if i did a port job??? if i run it with the stock motor like you said, would i have to change my cam at all???thanks for the help a lot, you might have saved me tons of money and time....

klumb15

one more question...does anybody know if this thing with the right carb and right air cleaner can fit under a ss hood on a camaro???

Sporter28

I put one of the B&M blowers on my loaded 1967 SS/RS-350 about 16 years ago and it would not fit under the SS hood. It did fit under a factory steel cowl induction hood off a 69 Z28. I had a Holley 750 VS and a low profile 2" air cleaner. BTW, I ran it on a completely stock 67 350 with true 10:1 compression and stock exhaust. Ran fine on 93 octane and ran 8.30s on real 80's street tires in the 1/8 mile, about a second quicker than stock.

S. Holley

I could not tell you if it would fit or not... (speaking about a 3rd gen) But I have seen this setup on several cars before.

as far as a port job that would help with air flow... so it would add power... but don't HOG THEM out... you may lose low end punch. RUN the MSD and have FUN!

97WS6SCharged

A roots blower is going to make boost from idle on up. Port the hell out of the heads and have fun.

S. Holley

TO much porting...(as in porting the hell out of them can effect your low end punch) This is not a race motor but street. if you use a higher rpm cam and plan to turn the motor high and hard... cool, but your factory camshaft works from .100 to .400 lift...maybe 4500-5000 rpm.

Just my .02

port sure...hog it out....not for stock motor stock cam engine.