Cole317

Hey guys,

I've been having some difficulty finding answers to supercharging.

1. For aluminum L98 heads i've been told they have a different bolt design requiring a certain kind of manifold. in other words, an 86 and under manifold design will not work. Similarly, the 87 and up vortec style heads will also not work. is this correct? If so, does that completely eliminate any weiand/b&m/holley mini blowers?

2. Here is my set up:
2 bolt main '89 Block CR is 9.6 to 1 (stock bottom end with 20k miles)
Ported and polished '89 alum. L98 heads
GM LT4 Hotcam Kit 218/228, Lift .525/.525 with 1.6 RR's
Holley 750 DP with mechanical secondaries
All that is with a Muncie M20 four speed and 3.08 gears.

3. My car feels great with this set up but I want more. Im looking to supercharge and I see one of the mini root blowers as the easiest way to get more power. Can i get away with just thicker head gaskets to lower the CR or do I need to actually swap pistons?

4. if not, does that just leave me with a centrifugal blower set up?

I know this is a lot so thanks for any help, i really appreciate it!

mnstrlt1

Ok- here is my opinion,

A centrifugal supercharger is going to be a lot easier, in terms of packaging, efficiency, and power potential. This route has also been documented thoroughly in the c4 community.

Initially, your post was a little confusing, because I wasn't sure what kind of supercharger you where looking for. At this point, it sounds like you're more interested in a top-mount (old school) blower.

I can't help you in that particular department because that type of supercharger (roots style or screw style) are essentially none existent in the C4 community primarily because you'll need more hood clearance, sometimes more clearance than the current cowl hoods on the market can offer. Heck, centrifugal superchargers on these cars is an uncommon sight.

The compression ratio sounds fine (depending on power goals). Old school guys, who ran 6-71, 8-71, etc. use to recommend 8:1 compression or LESS. This isn't the case anymore. The old-school blowers are not very efficient either.

I wouldn't suggest going with thicker head gaskets (too far out off factory spec). That's just a band-aid to reducing compression.

The best "first step" would be to tell us more about the goals and plans with the car and what kind of power you're trying to make.

If you want to get a supercharger sticking out of your hood, and want to exaggerate the look, I am certain "The Blower Shop" has the proper lower-intake manifold for your application, or one can be machined (using an existing casting, and re-drilling the proper bolt pattern for your heads). The end result might not be "all you expected" as far as power...

If you're trying to get something you can grow into (turn up the boost, or swap out the head unit), and have some "practicality" too, I'd suggest getting in touch with "Blower Works" (a supporting forum member).

This "can" get expensive...

illenema

You can drop a Vortech or similar right on that setup and will make 100-150 more hp just as is, good setup will cost 6K +-
Gregg at blowerworks.net

Cole317

I just always saw those mini blowers as a cheap, and easy install. I've considered the vortechs, paxtons, prochargers, etc. but the price was always a little higher than I wanted to spend....

So i'd be safe with my CR and stock bottom end to run a mild centrifugal set up? Thats my main concern...its a pretty fresh motor so I don't want to tear it all apart again.

Performance wise I just want it to have more. I got used to the current set up so it's time to upgrade!

Thanks for the help guys, really appreciate it!

illenema

Yes the kits are designed for stock motors, with low to moderate boost.
I have a vortech Vt T trim on a stock lt-1 no problems whatsoever. and screams, if you want to run high boost forged internals and lower compression would be needed. $$
The nice thing about mine is there is no hint of being supercharged until you get on it, passes smog- I would never run without a supercharger. I also run roots on my 74.

BlowerWorks

Hi Cole !
The heads on the L98 are all SBC. I believe the first Vortec heads were on the truck 5.7 and are different. Certainly all C4's use standard SBC heads. So any old manifold will bolt up but as others have said in conjunction with a positive displacement blower you'll need a new hood.
greg

Cole317

Man thank you so much i've been wondering about this FOREVER!

thanks everyone, your help is very much appreciated. I'll let you guys know what I end up doing, or of any problems i encounter!