I'm putting together a motor for N20.

What would be the biggest shot that yall would put on it.


355ci
GM forged steel crank
Eagle 4340 H beam rods
speed pro pistons
home ported heads
comp 224/230 cam

I was thinking about a dual stage around 200 to 250hp.
75 off the line, 150 to 175 second stage kicking in around 3000 rpms.

How big of a shot would yall go? I don't care anything about that punny 10 bolt rear that I have.

I'd love to get in the 10's with this setup and get kicked off the local dragstrip.

Car before was making 348 rwtq and 339 rwhp at 5500rpms, and the dyno man quit the pull at 5500 due to drop off in power which has been corrected, the crank broke. Don't know what the power would have peaked out on the dyno if the injector constant offsets had been correct.

Thanks

D Moss

 

the bigggest shot I would do has to do with how long do you expect the motor to last. I guess I would stop at 250 provided it was a 2 stage.

 

With an all forged bottom-end a 250 shot sounds good to me.

 

Oh, a small change. I was going to run H beam rods, but now I have to run I beam rods instead since I have forged pistons that have a pressed pin instead of floating pistons....(There are no H beam rods for pressed pins, and I wasn't going to buy another set of forged pistons)

I ordered scat I beam rods. I told the guy on the phone to send me the strongest rod that he had that was I beam.

Will this keep me from shooting 250 hp safely?

Thanks

D Moss

 

The Scat I beams are great rods... I'm running Scat I beams in my 383 using a 300 shot... Did he send you the pro series ones with the 7/16" rod bolts??? I shift mine at 6400 rpm, and run 10's all day with them... I'm happy..

 

I told him to send me the strongest I beam that he had, and this is what he sent me....

SBC Scat 2-ICR5700P (5.700" x 2.100" Press pin)

This is from cncmotorsports.

D Moss

 

That's actually where I bought my rods from.... lol... The part number you gave was for the 3/8" rod bolts...

I just realized that they only make the 7/16" rod bolted rods for bushed pistons... Since yours are pressed, the 3/8" 's are what you had to go with... They should be plenty tough though... They are good ARP rod bolts....

 

I bought the Scat 4340 Forged I-beam rods as well with the 3/8" capscrew bolts, but the bolts say "scat" on them. Who makes scat's bolts?

 

I should have updated this post.

I went with the pressed fit rods, but long story short, I ended up buying floating forged pistons and using the h-beam rods.

So now I have

GM steel crank (not cast)
eagle h beam rods
speed pro floating forged pistons,
GM 847 cam

Still thinking about that 200 shot.

 

you will easily be able to handle a 200 shot, if it were me i would even go with a 300, maybe even 350, why not if you put all that money in it to hold it. your motor should be able to handle it and as long as you don't kill it off the line at the track the rearend should be fine. i know tons of people running in the 10's with the stock rearend.