Big Bore short stroke??

[late96]

Any opinions on this? Late model, 360 spec alum. head, Alchohol, 1/2 mile, wrs55 tire.

[parrot69777]

Sounds like a Wissota engine to me.

[late96]

Yes for Wissota, but havn't ran this combo before. Looking for something differant. Forgot to mention swing arm car. Any opinions?? Thanks

[fast_crew]

If you don't mind turning the extra rpms go for it.

[dynoman14]

Big Bore Advantages ;
If you want to find out the power gains on a big bore engine get your cylinder heads flowed on a 4" fixture and then on a 4.155" fixture. That will tell you if your heads will pick up from cylinder de-shrouding. A decent set of heads will usually pick up 5-15 cfm @ 25" which equates to 10-30HP. If the heads don't pick up you need to get them to someone that knows how to use the valve seat angles to get maximim low lift intake flow.

If you select your crank, rods and pistons right, the reduction in reciprocating mass is pretty significant in acceleration on the chassis dyno.

If you go this direction make sure you get a camshaft designed to jump the valve of the seat earlier in the intake cycle and faster off the seat. As with any race engine, earlier / faster on the intake always makes more power. This should let you match the potential increased acceleration of the engine and drivetrain.

As far as fast crew says, additional RPM's need to be addressed with the right valvetrains pieces but just remember. If you can turn 1000 more rpms than the next guy, that is 1000 more power strokes in one minute; on an 8000 rpm comparison that is a potential of 12.5% more power output to the track if both engines are equal. In the real world a good big bore engines is already better on power output so the additional rpms are just an added benefit.

Kinda like having an awesome looking girlfriend, that likes to cook...

Spec heads of any type usually like a bigger bore. I am doing an "outlaw" crate to run with open LM's with big bore ( 604 gets 200# over opens ) and we'll be on the dyno in a week or two. With compression and camshaft and 7500rpms it should be 150hp better than the stock 604.