I just heard about something called the Box engine or soething like that?

bore = stroke

I hear they are terrible and are almost incapable of prodcucing any decent power.

any truth to this? anyone care to comment? isn't a 406 a 4.03'' bore and a 4'' stroke

 

i lived with my family at beck and 6 mile. a buddy of mine with a 99SS, NBM and also a board member lives b/t 6 and 7 mile on merriman. black something subdivisoin

 

Most 406's are 4.155 bore x 3.75 stroke

 

""""

Not to harp but no 800hp cup motors have 300g pistons. Restrictor-plate stuff isn't even that light on most teams!

I think what Danno was saying which is true is that with all else held equal more stroke will actually make more power due to friction reduction on any given engine due to the aero limitations of the cylinder heads ability to feed that given piston speed before the heads back up. This means that the heads now stall at a lower and more friction friendly rpm due to the bigger inch engines demands on them. Just one of the reasons you usually make more power even with the same heads on a larger engine.

 

i meant a 4'' 30 over and 4 inch stroke
which is a 408 actually... my mistake

doesn't jordan have a480rwhp 408?

 

anyone have any expierence with equal stroke/bore motors?

 

Its just an engine. Square, over square, under square just another internal combustion engine.

 

It's what I've heard of on 700+hp NASCAR Motors in classes that don't have nearly the Winston Cup Budget, that and the pin weight was deduced by material and tubing size formula's

With a small enough pin boss and very tiny skirts a 300g range for a 4.180" piston is light but the technology out there to pull something like that off. Granted it's not cheap.

What have you heard?

BTW I don't think Dan even said that the longer stroke motor had less friction, it's actually the other way around. Yeah the same port on a larger sube motor will peak at a lower RPM, something that more camshaft will not fix very well. One of those reasons that a 383 doesn't really like LT1 heads.

Bret

 

No most Cup stuff is around 400g. We have many guys working all the big teams. There have been some pistons around 390 or so but they have to soak up 800 hp worth of heat for 500 miles, The restrictor stuff is sometimes 370 or so. Some Cup pistons are even as heavy still as 435 as we have one like that right now at school from evernham. These are like 4.135 bore or so.

 

Interesting stuff.

Piston 4.180" around 400g
Pin, shorter and smaller around than street stuff, around 75g
Locks, 3g
Rods, They are limited down to 525g, so the recipricating mass there is light let's say 150g
Rings, narrow rings don't just cause less drag but have less weight too. So around 35g for rings.

663g vs the 780g on the normal stuff.

The piston speed of a Winston Cup motor at 9500 is about 5162ft/min, the piston g's are 5260.

.663g x 5260 x 9.81 = 34211 N = 7690 lbs of F

So that's a good amount of Force working to pull the piston out of the rod.

Bret

 

Brett,

I don't think you are allowed to go much bigger than that big a bore in WC either. I can't remember but I think it's like 4.165 max now so the Ford's don't have an advantage over the Chevy or the Dodge's don't either. They all have the same limit now whatever that is. The Dodge can go 4.250 easy otherwise and would slam the Chevys even more than the Ford's do. Still not a lot of difference between a 4.180 and that anyway though. At first it was limited to 4.185 and now I think it is even smaller.

 

I knew they limited the bore the first time since Dodge designed that R block to take one helluva big bore, didn't hear that they did it again. Seems that you would let them have the biggest bore possible that they all could run to me.

Bret

 

You may be right and it still may be 4.185. The Dodge small block has larger bore spacing so they could put more bore if they wanted and there was no rule. Of course they already let them (Mopar) run a head unlike anything they have ever made just like Chevy so they wouldn't let them also have a 4.250 bore.

 

Yeah those P7 and SB2.2 heads are not anything like production unlike the Yates heads which are just really good Cleveland heads.

I know the P7 and SB2.2 are pretty close to the same head, if you could have such a thing, but I'm not 100% sure if they all have the same valve angle and cant (including the Yates castings)

Bret

 

The Fords used to be so much more powerful that they removed the cant from Fords in the NASCAR legal Yates head to supposedly allow the GM products help close the HP gap. Now you have rotated and canted valve small block Chevies and Mopars which never had anything of the kind ever and the Fords, which really did have many canted valve engines from the 351 cleveland to the 400M and the 351M and the Boss 302s, CAN'T run canted valves! The crazy thing is that most of the Chevy dumbasses don't even know this and they think the SB2 is really a chevy type head. It even has the Ford style straight wall.

Worse yet is the NHRA who outlawed all good Ford heads for Pro-Stock truck and then complained that no one would run a Ford! You couldn't run a canted valve Ford or even an SC1 Yates even in Pro-Stock on a Ford which again came with these type heads right from the factory. Chevy, on the other hand, was allowed by the NHRA to run the special purpose built IMSA Intrepid/SCCA Trans Am corporate GM motor with it's Ford 302 copy 8.2 inch deck and Ford style symmetrical canted valve heads! I used to believe that the SBC was a superior small block but I know the Ford stuff is way up on it now. It doesn't matter though because all the good canted valve Ford stuff is banned except in outlaw racing where it does dominate in like 8 sanctioning bodies, Super Street NMCA etc. Even all the Chevy people run Fords in these few classes that allow the good Ford stuff.