355 parts for a big shot of N2O...

I was refered here from LT1 tech. They said to gauge you you GAS guys thought.

Here it is:
355 forged bottom end, what parts to get...
I am contemplating go the fully forged 355 route. Now I am not going to say, "Money is not a problem." I don't mind spending some good coin for some good parts, but I am not going for the absolute most expensive pieces.

So lets say, I want to run a heads/cam fully forged (yes crank also) 355 with say a 200 - 250 shot on it.

What would be a good set of pistons? I am probably shooting for high compression since that won't affect the nitrous at all.

What size and brand of rods should I go with?

What is a GOOD crank? I know these can get expensive, but what is a good forged crank.

ALso, what all is definately needed while building a 355, machining whise? Obviously the cylinders will be bored .030 over, so what else should I do at the same time. Is balancing and blueprinting necessary?

How much is a setup up like this going to net rwhp wise? Probably looking at something along the lines of the CC306 cam size with some NICE heads. Thanks guys.

Crank: Callies "Dragonslayer"
Rods: Lunati "Pro Mod"
Pistons: JE or Ross (get a piston designed specifically for N2O and upgrade the wrist pin).

Rich Krause

Rich has suggested excellent reciprocating parts. If your budget does not allow for parts of that caliber, there are less expensive alternatives. When shopping for a crank, try to get a 4340 forging. Scat and Eagle both offer good cranks at the $500 level.
These companies offer good 4340 rods in I-beam and H-beam styles as well that can be picked up for around $400. Which ones?--I beams are stronger in compressive loads( nitrous) while H-beams have better tensile strength( high rpm). At this level it doesn't much matter and either is a good choice. Je, Ross, Srp pistons are all good, and all 3 companies have specific nitrous pistons available, although standard forged ones are fine for a 250 shot. Don't get any litewight ones though, they usually don't have the necessary thickness in the piston tops for the high cylinder pressures of a nitrous motor, and the rings are too high up. They can't take the heat. Definitely, get the whole package balanced, this is very important! Also, get a good balancer, as this will help the motor live a lot longer.

I agree with the previous post.

Rich Krause

Thank you very much for the info. That is exactly what I was looking for.

So I would definately want a 4340 crank and rods, and more than likely I-beam rods.
What length rods are the most ideal for a 355 with spray?

This will definately be a stout car, correct? I am only used to a heads/LT4 hotcam Z28, so this is a whole different world for me.

Originally posted by texasTA
Thank you very much for the info. That is exactly what I was looking for.

So I would definately want a 4340 crank and rods, and more than likely I-beam rods.
What length rods are the most ideal for a 355 with spray?

This will definately be a stout car, correct? I am only used to a heads/LT4 hotcam Z28, so this is a whole different world for me.

It will be stout all right! To the point that you are going to need to carefully consider the rest of the combo if you want it to work right and to last. Fuel system, transmission, and rear end are all going to be issues with a 200+hp nitrous shot. Frankly, these things will be more critical than choice of internal engine components.

As far as rod length, nitrous pistons need more compression height to allow for proper thickness of the ring lands. This limits rod length. I'd say 5.7" or 5.875" at the most. If you wanted 5.875" rods that would probably necessitate a custom piston though. So 5.7" is probably the way to go as it will allow you to use an off the shelf piston.

Rich Krause

One question:

Would you guys consider a 200shot very large?

Many guys run 150-175 shots on stock bottoms ends. Would a set of forged pistons (cheap TRWs) on stock rods suffice for a 200shot/6500rpms/104 octane?

I'm picking up a shortblock with that basic combo (forged TRWs, stock rods/crank), and I'd like to get an idea what you guys think is a safe limit of nitrous.

thanks,
Ryan

Yes , and No.

If the stock parts are have been life cycled a lot( lots of miles or high output asked of them) then you will probably break.

If the stock crank and rods are fresh, and prepared correctly then 200 is ok.

for example, my 355 is using a 94 4-bolt block, 94 cast crank, 95 powdered metal rods and trw forged pistons.This made 620 hp for 3 seasons and on teardown bearings still look good.

The extent of prep on the crank was choosing a low mileage piece, having the journals trued and balancing the recip. assembly along with a fluidamper harmonic balancer. The powdered metal rods were also very low mileage pieces and I had them machined to accept arp rod bolts and the big ends resized. The rest was just paying attention to standard assembly practices.

With that said, asking a stock bottom end for 600+ HP is pretty close to the edge, and accepting the higher risk of damage is part of the game ;)