Boring Out Question

[Pete7072]

I replaced the whole top end of my bike a couple of weeks ago, with an entirely different top end jug, piston cam, the works. Now I have the old top end sitting in a box, and was considering a build up of the top end ( bore and hone .040 over ). Just wondering when the point comes to build the bottom end up. I know from experience with cars, when you build the top end up, you have to build the bottom end to compensate. Thanks

 

[duneracerweston]

You can build the topend to the max of what you can get "off the shelf" and not worry about the bottom end it will take more then you can put to it unless the oil pump fails

 

[11_FX4]

And the same goes with a car, you can build the top end and not worry about the bottom end.

 

[miami1]

an engine builder friend of mine told me that the rods in a small block chevy are good to 500hp. so what you really gain is less wieght with better rods

 

[MidwayUSA]

Stock small block Chevy rods will not hold up at 500 hp for long. Not even if you install ARP rod bolts.

 

[duneracerweston]

^^yep

 

[11_FX4]

A small block ford will hold that power...just not the block lol

 

[Pete7072]

you start pumping that kind of HP through any engine, and you're begging for problems. Yes the block will hold it, but then through in the torque, and you're asking for a bent rod.

 

[MidwayUSA]

Small block Fords can't handle near as much power as the Chevy rods because they have a 5/16" bolt compared to a 3/8" bolt on the Chevy rod. Ford Hi-Perf rods have the larger bolt, but cores with that rod are hard to come by. Most all the performance engine work we do get Eagle or Scat h-beam rods and 7/16" ARP 2000 series bolts when available.

 

[miami1]

lol.. he may have said 400hp its been awhile. i know he's a big fan of drilling the rods and puting bigger arp's in them. however if you have the $ to put 500hp in the top end of a small block why would you cheap out on the bottom end? i think its more of a low budget fix for circle track guys

 

['00 WO-YA!]

I replaced the whole top end of my bike a couple of weeks ago, with an entirely different top end jug, piston cam, the works. Now I have the old top end sitting in a box, and was considering a build up of the top end ( bore and hone .040 over ). Just wondering when the point comes to build the bottom end up. I know from experience with cars, when you build the top end up, you have to build the bottom end to compensate. Thanks

Damn this thread got off track!! Anyhow, as Weston said earlier the stock bottom in these things is fairly tough. The main thing would be to make sure that the condition of your stock components are good. Bearing/crankshaft wear & clearances, seals, stuff like that. Higher compression ratios will beat on the crank bearings & rpm's are what kill most engines. Couple those 2 together & you'd better be sure your stuff is in good shape!

 

[11_FX4]

Small block Fords can't handle near as much power as the Chevy rods because they have a 5/16" bolt compared to a 3/8" bolt on the Chevy rod. Ford Hi-Perf rods have the larger bolt, but cores with that rod are hard to come by. Most all the performance engine work we do get Eagle or Scat h-beam rods and 7/16" ARP 2000 series bolts when available.

We have plenty of customers who have a trick flow top end and stock bottom end with blowers and turbos running around with 450-600hp at the wheels. stock rods with good rod bolts will handle just as much as a stock block.

 

[duneracerweston]

And i bet those are street rods because a racer would've changed cranks before all of that heck I would change mine is I did that

 

[11_FX4]

two of them are show cars, but we have a bunch of street cars running around

 

[duneracerweston]

Ya stock crank will hold if not run hard constantly it is runnable but not fully reliable