400 sbc destroked to 350cc 11 to 1 comp and 87 oct gas

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Dec 17, 2010 | 02:07 PM

#51

Apeiron

Moderator

Joined: Jan 2000

Posts: 20,981

Likes: 11

From: Mercedes Norte, Heredia, Costa Rica

Car: 1984 Z28 Hardtop

Engine: 383 Carb

Transmission: 4L60

Axle/Gears: 3.54 Dana 44

Re: 400 sbc destroked to 350cc 11 to 1 comp and 87 oct gas

Quote:

Originally Posted by Doom86

David Kauffung's 305 made 400hp in 2007 at the Engine Masters Challenge, and 487hp in 2008 at the event and was DQ for an illegal oil pan.

How did it do on the street?

Dec 17, 2010 | 02:58 PM

#52

Doom86

Senior Member

Joined: Oct 2004

Posts: 965

Likes: 2

From: SE, Ohio

Car: '86 Z28, '91 RS

Engine: 305ci, 305ci

Transmission: TH200c (no kidding), TH700r4

Axle/Gears: 2.73, 2.73

Re: 400 sbc destroked to 350cc 11 to 1 comp and 87 oct gas

Quote:

Originally Posted by Apeiron

How did it do on the street?

No idea, it's a dyno queen if I'm not mistaken. Last I heard though he was looking for a car/truck to put it in. IIRC the 400hp was at 6.3k and the 487hp was at 6.6k.

He had it over 500hp at one of the local universities (lives north of me) but it pulled to 7k and he wisely went lower with the cam given the stock bottom end.

I don't think it's a perfect build we should copy, just showing what bigger valves in a 305 can do. He used 210cc GM Fastburn heads with 2.00 and 1.55 valves. Not the best choice of heads IMO, probably more suited for 8k peaks.

Dec 17, 2010 | 04:26 PM

#53

ASE doc

Supreme Member

Joined: Apr 2010

Posts: 4,337

Likes: 29

From: Aurora, OR

Car: 87 IROC Z28

Engine: 355 cid TPI

Transmission: Custom Built 700R4 w/3,500 stall

Axle/Gears: QP fab 9" 3.70 Truetrac

Re: 400 sbc destroked to 350cc 11 to 1 comp and 87 oct gas

Quote:

Originally Posted by basiccamaro

One thing, no matter what combo I was using- 400, 383, or 377, I would always use at least 5.7" long rods rather than the shorter, stock lenghth 5.65" 400 rods. I've yet to pull a 400 core apart that didn't have a lot more cylinder wall scuffing/wear than a comparable 350.

For my 377s, I used 400 +030 pistons with relocated pin holes for 6" rods. Then I installed 6.125" rods with the 3.5" crank. You can use a standard 3.48" 350 crank but the 3.5" gets you a couple more CID and tighter deck height. Keep in mind, 3.5" cranks and 6.125" rods are tricky, exotic, expensive peices. No one makes these in a cheap version.