Engine Difference

[nascardriver0723]

Say you had the 2 engines with all the same stuff on them, but one was a 358 ci and one was a 355 ci.. What would be the big difference? 100 More hp or so? More torque or what?

[OldSStroker]

Say you had the 2 engines with all the same stuff on them, but one was a 358 ci and one was a 355 ci.. What would be the big difference? 100 More hp or so? More torque or what?

Assuming everything was as identical as possible, the power and torque output would probably be about 358/355 = 1.0085 times as much. To put that in perspective, if the 355 was 400 hp, the 358 would probably be about 403.4 hp. At 800 hp it's nearer 813.6 hp.

NASCAR Cup engine builders would sell their mothers for 13 hp.

FWIW, if you are building for a 358.0 max class limit and don't have million$, you could get 4 "seasons" of an engine if you freshen it each year.

Start with a good CNC new block. Assume 3.500 stroke .

Initial build with 4.000 bore =351.86 cubes
First .010 rehone 4.010 bore = 353.62
Second .010 4.020 bore = 355.39
Third .010 4.030 bore = 357.20

The difference largest to smallest is about 1.5% or probably less than 10 hp on a 600 hp engine. Also, as your car and driver get better, they'll have a bit more power.

If you are "Cup-rich" and can clean up the bores after one race with a .005 rehone, and have cranks with virtually any stroke, you could rebuild the block a number of times going from say 4.170 to 4.185 bore and keep the cubes just under the 358 limit with minor stroke changes. Of course the rotating/reciprocating stuff gets replaced at every rebuild in this case.

[nascardriver0723]

So on a short track, it pretty much wouldent make a difference, huh?

[bill jones]

-if you give away ten of those 1.5 percent's and the guys you are racing against all have'm, who's going to win?

[nascardriver0723]

Hm.. Good Thought......

[OldSStroker]

-if you give away ten of those 1.5 percent's and the guys you are racing against all have'm, who's going to win?

If "Speed costs money...how fast do you want to go?" applies, and you can afford to restroke your crank or replace the block after every rebuild, build a 357.8 inch engine the first time. I'd rather spend the money on a good shortblock just once, and spend the rest of the money I save on the airflow part of the engine.

FWIW, at the local circle tracks there's a lot more than 10% power between the winners and the also-rans. I'd try to keep the 1.5% from optimum just to the engine, and not the rest of the car.

But we digress....