How much octane additive w/ a blower & 10:1 compression???

......Hello Everyone, I hope all of you folks had a Happy Turkey Day!!! I've got an idea but wanted to run it by everyone before acting on it. I have a 413 small block Chev in my '32 Ford. 10:1 compression, AFR 195 heads, cam is 230/236 @ .050" w/ .518 lift on a 110 LSA. If I put an 8:71 GMC on it, is it feasible to just use octane boost instead of race gas to keep it from pinging, etc? And if so, how much would I need? The local gas is 91 octane. Also, from my understanding a large cam bleeds off compression so why not just put in a huge cam to lower the compression??? Thanks ;) Bill

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Originally Posted by billlsbird

......Hello Everyone, I hope all of you folks had a Happy Turkey Day!!! I've got an idea but wanted to run it by everyone before acting on it. I have a 413 small block Chev in my '32 Ford. 10:1 compression, AFR 195 heads, cam is 230/236 @ .050" w/ .518 lift on a 110 LSA. If I put an 8:71 GMC on it, is it feasible to just use octane boost instead of race gas to keep it from pinging, etc? And if so, how much would I need? The local gas is 91 octane. Also, from my understanding a large cam bleeds off compression so why not just put in a huge cam to lower the compression??? Thanks ;) Bill

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Bill,what pistons are you running?
Is this engine 4.155 bore x 3.80 stroke?

To get started check out

http://www.blowerdriveservice.com/techcharts.php

That's a lot of huffer for a 413. Wouldn't a 6-71 be a better fit? Running around on race fuel sucks, been there and done that. Realistically you probably won't be able to run more than 4-6 psi boost.

Kitz

Hi Eric, no it's a 4.185 bore & a 3.75 stroke with forged aluminum pistons. Thanks, Bill

Don't do it. You will not be happy with the results. A blower engine needs to be designed from the bottom up if it is going to run efficiently. Octane boost will not raise your octane enough to compensate.

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Originally Posted by billlsbird

Hi Eric, no it's a 4.185 bore & a 3.75 stroke with forged aluminum pistons. Thanks, Bill

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With that over-bore it will be very hard to keep head gaskets in it.
My advice would be put in a larger hyd. roller cam or a smaller mech. roller cam.
With the right cam and those heads you will be over the 500 hp area.

.....Thanks, I was afraid this is what I'd hear... BUT, better to hear it & not do it than to do it & be sorry! ;).... My HP is 460 now & TQ 499, so I guess with a bigger cam I'd pick up 40 + HP? And my Torque converter has a true stall of 3000 so it'd handle a bigger cam.... I now have a Edelbrock Performer RPM Air Gap manifold w/ a 750 double pumper. Would you recommend a Victor Jr.??? THANKS, ;) Bill

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Originally Posted by billlsbird

.....Thanks, I was afraid this is what I'd hear... BUT, better to hear it & not do it than to do it & be sorry! ;).... My HP is 460 now & TQ 499, so I guess with a bigger cam I'd pick up 40 + HP? And my Torque converter has a true stall of 3000 so it'd handle a bigger cam.... I now have a Edelbrock Performer RPM Air Gap manifold w/ a 750 double pumper. Would you recommend a Victor Jr.??? THANKS, ;) Bill

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Yes,a Victor will help in the upper rpms.

....Thanks ;)