I built my 383 with 4340 H-beam rods, 4340 Cola Crank, forged SLP pistons, balanced, ARM bolts through out the engine.

How much juice do you think I could safely handle with these parts? 250 shot ok?



Reid

 

What kinda of shot, wet or dry?

As long as the fuel is up to snuff id think a 250 is fine.

But this should be discussed in the n2o forum. Thanks.

 

I am running 11.8:1. And I run C-12 when using juice at the track.


As for the wrong forum, I am talking fored parts in general. How much they can take, not necesarily using juice. Just how strong forged parts are.

 

I'll give you my own, admittedly idiosyncratic "rule of thumb" on this. The numbers reflect my own experience. Others are free to disagree. They assume no detonation, just on the mechanical strength of the parts. They are based on an optimum tune and assembly and are only in reference to domestic small block V-8's. This does not apply to race engines, that operate for brief periods with frequent rebuilds. There are for the kind of use I put a motor to: street/strip performance. So while not achieving OEM longeivty, I'm not talking time bombs here either.

Stock parts: ~1.3hp/ci (~450hp for a 350)
Mid level aftermarket buildup: ~2hp/ci (~700hp)
High-end parts: ~2.5hp/ci (~900hp)

Other notes: I am talking about crankshaft hp. A centrifugal car, for example, eats up 50+hp internally to drive the blower, so a somewhat lower guideline should be used. The parts you mention are kind of low mid-range, so figure 600hp or a bit more so. IOW, if the motor makes 400hp off the spray, 200 should be ok, 250 would be an upper limit.

Don't expect me to defend my guidelines based on any engineering or other fancy theory. Just based on my observations.

Rich Krause

 

I think it depends on which power adder you are using. I think Nitrous would be the least because of the heat on the pistons and high peak cylinder pressures because the mixture is burning faster. And also with nitrous you would probably be turning more RPM's than with a blower or turbo.

With a blower the only disadvantage I see is side loading the crank.

I think the turbo is the easiest on parts because you can turn fewer RPM's and still make alot of power.

My guess for each, and this is not based on anything scientific:

Nitrous: 700
Blower: 800 (the blower would eat 75-100 HP at this level more than a turbo)
Turbo: 900

I know most piston manufactors rate their 4032 material pistons at 250HP. I think thats what the SRP pistons are made from. Of course I know guys that have sprayed about 100 more (350) and didn't have any problems, but they also knew what they were doing with the tune and were careful. Im sure there are also guys that could melt down a motor with a 100 shot.

 

SRP Pistons have a much higher Silicone content then the JE line or any other forged line. They will not stand up to the beating of even say a TRW. If you have SRP I wouldn't use more then 200 -225. They also are not a full skirt piston and they tend to rock under high load causing failure ( Ihave a couple on my wall to prove that). A little more advice run at least C16 not C12. C16 is a slower burning fuel and it will help reduce detonation. Its hard on plugs but its much easier on pistons and valves. Good Luck.


Vince

 

Well thats the thing. I don't get any knock retard at all. It seems to be working great.

I have run a 200 shot quite a few times already, but wanted to throw in the 250 jets and see what happens.

 

What kinda jetting, timing, fuel presure, and delivery system are using. Are you sure you have a true 200hp shot? I know a 250hp fogger tuneup is good for 20-25mph on the top end over a straight motor pass.

Vince

BTW: What do your plugs look like?