What is the relation there, provided the cams are held constant. Is the larger primary more for the stroke or for the bore?


Jason

 

Would it not have more to do with total cylinder volume moved after combustion? Seems that stroke and bore are variables in the effective volume.

 

I think it's more related to the exhaust port cross section of the head.....

 

What is a good header to use on an ITR. Is the Hi-Tech system the best way to go? I want a header and exhaust system that will work with any future modifications I perform to the engine and car.
Thanks

 

Maybe I should reword it.
If the engine specs are 81 mm bore and 81 mm stroke, .030" head gasket, .005" deck height, 45.5 cc cylinder head volume, 83 MM gasket bore, and a piston dish done of -7.0 CC, you get a compression of 10.647:1, if you increase the bore to 82 MM, compression changes to 10.883:1, and if you hold the bore constant at 81 MM and change the stroke to 82 MM, you get a compression of 10.766:1.
Now, seeing as how, if that is the correct calculation, the change in bore seems to have a bigger difference in compression. But, then does that mean the bore has a bigger demand on header flow characteristics, or required primary size, than an increase in stroke of the same size?
That is how I should have worded it. They both net the same displacement, but one nets more compression. Which to me says it has more pressure in the cylinder walls.
I see it like fuel pressure with the same size injector. If the injector size (like the port size in the head) is held constant, but the pressure in the rail (cylinder wall in the application) is increased, the fow of that injector is effectivly increased.
I think I just lost myself...


Jason