I am building a 383 with 6inch rod and have a question on the JE/SRP pistons part number#138093 Will these pistons stand up to the nitrous shot I am going to spray 250+ I only plan on spraying a 250 but If I dont get to the 9s in the 1/4 on the 250 I will spray more until I do. I have looked at quiet a few piston but most recomend up to 250 shot of nitrous. Are the SRP pistons that I mentened up to the Task of a big shot? Or any other suggestions?
Thanks for any help

 

For a big shot of juice, you generally want to drop the ring pack down a little on the piston, increasing the thickness above the top ring, and keeping the top ring out of the heat. Do that with a 6" rod, and the rings are going to be too far down on the wrist pin holes. And the top of the piston can't be as strong as it would be with say a 5.875" rod.

 

Well I am a little to far along now to go back with a 5.7 rod or 5.875 rod. How do you think the 6inch rods and the SRP pistons that I mentend will do?Or last when I spray it? So is it safe to say a 6inch rod should only be used in N/A engine?
Thanks for your help

 

Call JE.

Rich Krause

 

get buttons and you should be fine.

 

There are people on here spraying 200 on TRW's, so I dont think you will have a problem.

 

I may be dumb, but I would think you would break a rod before piston...

What rods are you running??

 

A big nitrous shot is hard on a variety of parts, but the pistons do take quite a beating due to the high temps and high preak pressures. When you start to get to the 200+hp range I think you really need to start to consider a staged system or at least bringin the nitrous in at a relatively high rpm. Bringing in that much nitrous at low rpm can be tough on a motor. I am using a max of 250hp in a single stage system, but I don't bring it in until 4,400rpm or so. And I am using very stout parts.

Rich Krause

 

I will be using 4340 eagle H beam rods with the L-19 bolt upgrade. I will be converting to a turbo setup next winter.
As far as the 6inch rods go what would be an appplication were you would want to use them in a sbc 350 motor if they are not good for nitrous or turbo or supercharger? Would it just be for a N/A engine for a better rod angle?

 

People make WAY to much of the rod length thing. FWIW, I prefer short rods for a boosted or nitrous motor for two reasons. Shorter rods mean less dwell time near TDC and thus lead to lower peak cylinder pressure. This in turn leads to less tendency toward etonation and less stress on parts. Though the difference is small, I figure every little bit helps. Then there is the issue of leaving enough room above the pin for the ring package. Look at the thickness of the top ring land on a blower/nitrous piston. Very thick. The less the wrist pin intrudes here the better, as far as I am concerned. Though, as was mentioned, there are ways to support the rings if they cross the pin bore (buttons, etc.).

The issue of cylinder wear due to increased side thrust with short rods is a moot point. A boosted/nitrous motor will end up being rebuilt long before that becomes an issue. The big advantage of long rods is the lighter piston weight when a shorter compression height is used. That can be an advantage in a high rpm istuation and places less stress on the rest of the rotating assy.

One other thing to mention, high rpm increases tensile forces on the rod and thus stresses rod bolts. The added stress from a blower or nitrous setup is largely compression, since these are usually relatively low rpm motors. So, I'd rather spend more money on the rods than the bolts in a boost or nitrous situation, though good rod bolts are nice in any situation. Just if the budget won't allow both, that's where I'd put the $$$.

Rich Krause

 

Thanks for all the replies. I have learned a lot. My next build will be better built thanks to you guys