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Old 08-19-2010, 06:54 AM
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Originally Posted by blownmazda
hello im wondering if its possible to get around 700hp from a 355 sbc with a 6-71 blower? id be using it for drag racing mostly and possible spirited street driving. im just trying to see where i can go with my motor due to recent need of rebuild. just seeing if anyones done this before with advice, ive read a few magazine dyno test that show 355 can do it.
I'm going to guess that this is just a "toss it out there and see" type of question.

If you're serious, you'd do well to do as much research as possible into what's required. A thread on this forum will not be sufficient- unless someone was willing to dedicate HOURS of their time to educate you on all the nuances involved.

700 HP requires good parts- the number of production parts that would go into an engine like that- if I built it or oversaw the build- would be counted on one hand, if that. And unless there were a reason like rules for a particular racing class I was trying for, I wouldn't build a 700 HP SBC in the first place. IMO, this is BBC territory.

There's no sense in building the engine so small. In that you're going to be using an aftermarket block anyway, and an aftermarket rotator, you might just as well build at least a 427 SBC from the get-go.

Now, there are guys who'll tell you that cast cranks or OEM steel cranks w/o a BBC snout or w/o dual keyways is fine, and that 2-bolt production blocks are fine, that cast pistons and OEM rods are fine, etc. ad nauseum.

Reality often clashes w/these "recommendations", however. This type of build offers ZERO margin for ANY error. Even if it is perfect AFA the tune goes, there's no guarantee the crank won't fail or the piston's ring lands won't pinch the rings or the rods won't come apart. This can happen even w/GOOD parts if there is one little failure- like in fuel delivery or ignition timing.

Often what you will find at the bottom of all this fertilizer, is the HP they THINK they're making, isn't anywhere near what they ARE making. If all you want is a short-fused, cross-your-fingers-and-hope engine, I cannot offer anything but a head-shaking "good luck". Keep the OEM parts below 450-500 HP at the most and you'll be OK. Go to 700 HP and you'll need a magnet to pick up the litter.

If you want something that will actually make 700 HP w/a modicum of reliability, be prepared to get into some serious cash outlay. Like 5 figures' worth. Just the induction system could go $5K w/o a problem.

Now, all that said- why don't you start out w/a stout 355 w/about 400-450 HP to get you started. If you've never driven a decent car set up w/450 HP, you'll be surprised how "lively" it can be.

In other words- walk first- THEN run.
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