Is it possible to buy just blower pistons and swap them with the stock hypereutchetics? Or, to get blower pistons in, the entire rotating mass... crank, rods, pistons, flywheel, and balancer need to go to the shop.

 

Most "blower" pistons are heavier than hyperu's. So you would have a balance problem, the extent determined by the difference in weight. Ideally, the rotating assy. should be rebalanced. It's out anyway, so it's just a matter of the cost. And it shouldn't be terribly expensive. OTOH, is it absolutely necessary? Maybe not. I am not sure of the stocker's weight, but many people say if the difference is less than ~20g, balancing isn't absolutely needed. If you didn't balance, at the least there would be more vibration. There may be decreased crank lengevity, especially if you rev it really high (unusual for a street or steet/strip blower app).

Rich Krause

 

Thanks... I just wanted to beef up the bottom end. My motor currently has only 9,000 miles on it. I suppose I can just run 6#s through a twin flow intercooler until one of the hypers collapse.

It costs about $3000 to re-do a bottom end (block work $1400 and parts $1600)... maybe cheaper at some places. Port heads $1300, then the blower cam and timing chain add $500.

So, I'll just run what I've got for now for a bottom end.

 

The prices you mention seem a bit out of line. If you have a motor with only 9,000 miles it shouldn't need any block work to install a set of pistons. Even if you do a stroker, on a 9,000m motor all it needs is clearancing for a new crank.

I had a professional race shop "freshen up" my block this year. Cost ~$900 including parts to tear down, clean, check dimensions and condition, reinstall rotating assy. with new rings, bearings, oil pump, gaskets, and a partial block fill, paint and reassemble. And I seem to pay top dollar for everything, if the posts here are to be believed. Aside from the motor R+R you should be able to have a new set of pistons installed for ~$1.2-1.5K including parts.

Rich krause

 

Thanks, the block work was to include decking, align honing, cam bearing install, clearancing, and splaying the caps.

I've heard of people running 450 HP to the stock crank and 2-bolt mains. Short term goal, I'd like to get 400 HP at the RWHP... which plus 14-17% for a manual drivetrain would put me at the 460 Flywheel HP range. I didn't want to overstress the stock crank and 2-bolts as I hear they are good up to 450 HP (flywheel).

That's why I was going to splay the caps... overkill?

 

2-bolt caps with studs and stock crank should be good to ~500hp.

Rich

 

That's 500 RWHP... right?

 

I had 475 rwhp on my last 355 with 2-bolt mains , stock crank & rods with TRW forged pistons, 8lbs boost. When I tore the motor down I had a cracked crank, Rods were twisting along with the crank and tearing up rod & main bearings. Personally I wouldn't feel safe with stock bottom end over 425 rwhp.

 

Yes, but as the previous post seems to indicate, YMMV.

Rich Krause

 

I only paid $460 for my machining work and that was for a .030 over bore and resizing the rods, polishing up the crank, installing the new pistons on the rods, and putting in the cam bearings. Total was on par with what rich said about $1400 for the short block with the new pistons, me doing the assembly though.

I'm running 16 psi on Speed Pro blower pistons stock crank and rods with ARP bolts. I never rev over 6K though.

Bill

 

Thanks guys, Sorry about the questions, but since I'm going blown... I want to get it right the first time.