davebat

Here's what I came up with, rather lengthy but very informative. Love to hear any feedback.
I’m going to be running a sbc 400 in a modified (asphalt oval) this year and we are limited to 406 cubic inch, naturally aspirated power plant.
The problem was, that if I spent oodles on my block to make sure it has the power and endurance I would need, it would soon be no good to me, or I’d be illegal because after refreshening the block beyond .30 over, I’d be over the 406 cubic inches that we are restricted to. So, this is what I came up with:
I figured that I could de-stroke the sbc 400 and stay under the 406 cubic inches.
HERE’S WHAT I DID (with excellent results);
On my primary engine, it needed to be bored .40 over, splayed 4 bolt mains added (was a 2 bolt), decked for cleanup only.
-Callies Compstar balanced, 3.625 stroke crank
-6” Manley rods, rated for 200,000 lbs
-Ross 9cc dome pistons w/1.196 deck height
-Comp Cams roller lifters, roller rockers roller cam;
12-940-9, circle track, Gross valve lift 0.645 0.63, duration @ 0.02 Tappet lift 290 300, Valve timing @ 0.05 Int 24open 56closed, exh 58open 26closed, lobe lift 0.43 0.42, lobe sep 106
-Comp Cams valve springs, 943-16 @551 lbs operating
-Dart ported heads (to match intake) 58cc chambers, 220 runners, 208 int., 160 exh. With Manley stainless high endurance valves
-Edelbrock ported Super Victor intake
-Holley 850 DP (76 jets)
-Regular race parts such as High volume oil pump, stud girdles, headers, high volume fuel pump, water pump, etc.
RESULTS;
Dyno results;
593 HP @ 7,000 rpm, 38 degree timing. Engine dynoed to 7,500 rpm 586hp, BSFC .44
This “de-stroked” 400 is now a 395 cubic inch with 13.5:1
You can watch the 7,500 rpm dyno pull on u tube: http://www.youtube.com/watch?v=i57Do3_x3Hs

fla1976

Sounds really strong. Music to a racers ears. Great way to stay within the 406 limitation.

davebat

Thanks. Can't wait to dyno the 400 I have for backup engine. If I use the same heads, intake and carb, should be close to identical except the stroke which will be 3.750. Using JE Sportsman pistons instead of Ross, but they are 9cc also.

ron19

I used a 395 (destroked 400, bored .040 over) in my dirt modified. It was a great combination. Not too much torque to break tires loose off the corner, but awesome acceleration down the straight. I was pulling mine 7800+ all day. Of course I used a Dart block, lgt wgt crank, billet ultra lgt rods, shaft rockers, etc. This things has a ton of power and explodes like a rocket once your off the corner. Good luck to ya, and if you need another motor, I'm selling mine...lol.

davebat

Ecxellent. Thanks, yopu the first I've heard of using the de-stroker for circle track.
If you have the time can you post or pm the specs? I have a friend who might be interested.

gdmii

Looks like a good combo Dave. Should give you some reliable horsepower. Congrats on a good job. Post your results on the 400 when you get them. I'd be interested to see how it stacks up.

George

ron19

This is the list I had when I posted to some circle track websites. I hope this isn't a problem posting here, if so I'll remove it, but since you asked:

395 ci.
Dart block
Dart Pro 1 heads, CNC w/matching intake
Billet Oliver lt wgt rods
lt wgt Callies crank
Jesel shaft rockers
Canton pan
Too much to list, all the best
All work done by Rhyne's.
8000+ rpm all day
$10,000 or best (serious only)
815-405-7167

cncmotorsports

Do you have a dyno chart to see the average power ?
We are in the works right now doing a destroked engine for a wissota modified. 4.155 bore. Eagle 43 pounds crank, 3.350 stroke, 6.200 Eagle featherweight rods, Custom JE pistons. Puts us right at 363.
Just curious to see how the torque and hp look form the 4500 to 7500 range on the build.
Did you dyno on gas ? or alky ?

ron19

Sorry CNC, I never dyno'd the combo. The engine shop I go to (Not to tout them too much) they build ARCA engines and all the top Late Model and Mod engines around here. The son ran UMP Mod and won several championships, and I picked his brain (very nice guys and very open with information). It was his idea to go this way with the bore and stroke. Everyone around here was building big cubic inch motors and blowing the tires off, while the top guys were building smaller cubic inches and reving them real high. He said that if he was to do it again, he would go somewhere in the middle, as the smaller engine struggled qualifying and when the track was tacky. So, with this combo, although I can't pull a 434 or 421 when its tacky, I hang right with them. When it slicks up real good on a typical Indiana summer night, I pull them around the track because I don't have a bunch of low end power to spin the tires of the corner, but it's literally a rocketship down the straight. It's the most awesome combo I've had.

cncmotorsports

Thanks, When we finish up our combo I will post the results, It's for the Wissota Modified class, so we are restricted to the World Products sportsman spec heads, by the we are shooting for 600-610 HP.