Technical > Matt Shaff's Engine Shop

Adding a blower to a 13:1 engine

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Big Rhino:
Well, it looks like I have a new mission.  Searching for a hemi....... ;)

225digger:
if you want the BBC , but also want the bottom end of the hemi look into the new century aluminum blocks , they have mains like a hemi and are alittle more stout than other aluminum blocks .

but you cant argue the fact about a blown hemi and parts aval

coupemerc:
Real good advice by the posts above. I've been a Chevy guy forever but when my buddy and I decided to run a TAD years ago we ended up going with a Hemi. We ran a "dragster" combination...438 CI (4.310 bore X 3.75 arm), 10.250" decks, 14-71@ 44%over, 11.8:1 CR, Crane R296 cam, 13 gallons/minute@4000 RPM pump speed. You will have 5 second horsepower. The blower will try to lift the heads off the block when you lean on it. Head clamping with 1/2" and sometimes 9/16" studs is the other other advantage of the Hemi. Also, parts are everywhere. Some of the Chevy guys were real fast (Dale Hall, Rick Santos) but I remember them being somewhat limited by the smaller wrist pins and weaker main webs. Having said all that, if you just want to go out and run a bunch of 7's then the Chevys are fine. My $.02

Big Rhino:
Finally back in the good ole USA.  Thanks a lot for all the really great info.  Lots to think about, need to get a plan on paper.  I really appreciate all the great technical opinions and experience.  Thanks again!

dreracecar:
Sorry to join the party so late

Things to consider
On a SBC unless you install the Magneto up front or run an offset drive the "10" will not fit--this adds to cost. I had to modify my rear bearing caps on my "6" to get the mag to clear.
Trying to run that big blower with a SBC that has a standard snout WILL rip the hub off the end of it. The snout barely sticks out of the front cover and by the time you get everything lined up pulley wise its going to be out there 4 1/2" past the front cover. Add another keyway to the hub and crank and look at the material left on the hub from the keyway to the seal surface--not very much. The 7/16 crank bolt is long and with a lot of threads , with even a good bolt, it will still stretch.
So heres what happens when you apply load/HP
The hub flexes at the point of where the crank ends, this flexing causes the crank bolt to flex and stretch along the threads(root dia of threads is smaller than shaft dia). As the bolt stretches the load is transfered to the end of the hub which splits the hub along the keyways for lack of material.
The only ways to combat these issues is to
With a stock crank snout--use a front crank support and hub (eliminates flex- but is $$$$$)
At minimum use a hub that has a BBC od but bored for SBC (ATI has them) After time might break the snout off but the hub wont split.
Get a SBC crank that has a BBC snout, BBC hub, Larger crank hub bolt (very$$$$$$$$$)

Personally I would rather run a SBC in 1/8 mile racing, too much weight to get moving running a BBC (thats why you need to build them BIG).

MY  Car
1650# w/ driver   375ci SBC 10.2comp  6-71 (20 over)  3.90 gear  leaves off idle   33"x 12" tire
1.06 - 60'   4.50 - 1/8  1/4= 7.00 @ 198mph (and more left) AND NOT HURTING PARTS!!!!!!

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