I'm in the middle of starting to build a crank driven centrifugal supercharge motor for some local No Prep racing next year, hopefully
The motor will be a BB wedge Koleno block with B1-MC heads, 4.5 bore with 4.375 stroke, the Vorteck V30-123A super charger is capable of 40+ lbs. boost and 4000 CFM.
I want to try racing it on E85 and i have no idea on what mechanical compression ratio to make it have to start with
Any and all suggestions will be greatly appreciated

I am just getting into this game, and everyone seems to come back with 8-9:1 even with E85 fuel....The motor I have dibs on is 8:1 and made nearly 1200hp at 22psi....at around 450ci

I've been told from up to 14.0 to 1 and down to 8.5 to 1 mechanical compression ratio
I know the NHRA blown alcohol racers use 11.5 to 1 and up to 13.5 to 1 compression ratio on methanol with a bunch of boost, 45+ lbs. boost and over 11,000 RPM
I've also been told that they are now making north of 4500 HP, I'm shooting for between 2200 and 2700 HP on E85 at or below 8500 RPM: luck:

I’d say it’s going to take pretty $eriou$ effort.
Please keep us posted

What will the boost pressure be at launch?

i have no idea, yet
This will be all new to me, boost, E85 and no prep
I'll have to try different things as far as starting line RPM, boost on the line and shift RPM, I have a lot to learn: wrench:
Hopefully it will be fun and not hurt a bunch of parts learning, hence me asking about the compression ratio now

If you have everything picked out, you can make a reasonable estimate of where the emap will be. A motor for boost
Will like flow as much as an NA motor, but the compression requirements are different no matter what youtubers like to say.
Will you be running an intercooler or relying strictly on the latent heat of vaporization of the fuel?

I've heard and been told no and yes on intercooling so far.
I know some guys who use to run an old style 392 hemi in Top Alcohol dragster, they were using Brad Andersen parts and his help on tuning. They had 12.0 to 1 compression ratio and Brad wanted them to increase it up to 13.+ to 1 ratio on straight methanol with the blowers available back then
I may try it first without an intercooler and monitor the manifold inlet temps and decide from them on adding intercoolers or not
I'm planning on going with really safe set ups to start with on all the tuning and see what it does and look at the plugs and time slips and go from there
I got a lot on my plate to get done before then so I'm in no rush, I'm trying to get everything right before starting hence my question on the compression ratios on E85 now
Thanks to all for your help on this

I would look at it a different way. As in, what is your goal?

ET/MPH at what weight or power at what rpm?

I think it's been said but basically as you raise compression, if everything else is optimized for it, you will make more power as you narrow your tuning window.

Said in another way, less room for error.

If I was building what I think you're trying to build I would do twin turbo and methanol.

How important is it to you to run E85? I think E85 is great for a boosted street driven car with restrictions on boost but this sounds like 100% race car. Just go straight to Methanol. Race car, race fuel. Put it at 12:1 compression and call someone like Bullet for the cam. I have a much smaller blower on a 405 cubic inch engine and it makes 11 psi on the brake and 38 psi by the 60 foot clocks. Making power won't be the problem for you. Managing it will.

[quote=. Making power won't be the problem for you. Managing it will. [/quote]
I'm hoping to make around 2000 HP to start with by reducing the supercharger drive RPM and work on hooking it and learning how to tune it and then thank about turning it up

I was trying to find the compressor map for the supercharger you picked, I couldn't find one, do you have one?

I don't have a clue what a super charger map is, sorry
In fact, I don't have a clue about what boost it will make at which crankshaft RPMs
I have a lot to learn, huh
Hopefully it won't kill me first

If you can get one, I will do some of the math work for you.

https://vortechsuperchargers.com/products/v-30-105a-supercharger?variant=34797400458


Is this it?

Yes Sir, that is the one I'm getting, hopefully soon