what do people normally do to build up their engine for a high n20 shot? all i really want my car to be is a big nitrous shot. i ultimatley want a 300 wet shot.

 

Civic SI motor or Integra GSR, stock internals, seems to be the way to go!


Or if you are a girl, you could build an all forged 4340 setup, 4bolt splayed mains, or a corvette straight 4 block. all the good machining. some coatings cant hurt on the pistons. basically either eagle or scat cranks, eagle or scat Hbeam rods, and JE or Ross pistons but depengind on how deep your wallets, callies dragonslayer crank, or lunati, oliver rods, and ross or mahle pistons

 

Well, maybe it's stating the obvious. But the answer is to build it really, really strong. Nitrous, especailly when brought in at relative low rpm generates huge cylinder pressures, that's why N2O makes a lot of torque at low rpm, it generates high cylinder pressures. This places mechanical strain on all of the engine components.

To single out one part that must be of the appropriate design and materials for a big nitrous shot, I'd have to pick the piston. Pistons designed for heavy N2O use will have a thick top ring land, a thick crown, and a strong wrist pin. I was inspecting my new JE nitrous/blower pistons the other day, the top ring land looked like it was about 3/8" thick or maybe more (I didn't measure). Looked about twice the thickness of the typical NA piston.

Obviously, the stronger the better for all the parts of a high performance motor, but one area where you probably don't have to go overboard is the rods. That's not to say you don't need good rods, just that they usually fail in tension, not compression. And most nitrous motors (unless all out race motors) don't turn really high rpm. The high cylinder pressure stresses the rods in compression, while high rpm stresses them in tension. So, something on the order of Lunati Pro-Mod or Oliver forged rods would probably be adequate. Even the Eagle H-beam would likely do the trick, though I don't much like Chinese stuff.

I could go on, but that should get you started.

Rich Krause

 

So you dont think that SRP -16cc pistons would be a good idea for a 300 shot Rich?

 

What is the pn? Are they a "nitrous" or "blower" piston? As I posted, the crown and the top ring land are thicker on a "nitrous" piston. Also, you should consider a wrist pin upgrade for a 300hp nitrous shot.

Rich Krause

 

PN 138106, they are just NA pistons.

If those dont sound good, what would be a good piston that is reasonably priced, doesnt HAVE to be american, cuz I know you are against the Japs, so am I, but Im also on a budget

Thanks rich

 

SRP also lists pistons designed for blower/nitrous apps. Look at page 5 of their catalog at http://www.jepistons.com/pdf/2002-srp-chevy.pdf I don't know the specifics of your motor, but they list a wide variety of compressions heights, so I imagine one will work for you unless your combo is really odd.

Rich Krause

 

When you guys say rods do you mean connecting rods or pushrods, or both? And does lunati make good pistons?

 

He meant connecting rods. The connecting rod takes a LOT of abuse in any engine. Assuming a built engine with a solid 300hp shot...you want a strong rod. I wouldn't go with an Eagle or Scat H-Beam rod either, I would go with an Oliver Forged or Billet rod, a Lunati Pro-Mod rod like Rich mentioned, or something in that ballpark. After seeing an Eagle H beam come through an oil pan last spring, I am now seeing the point of spending more than $300-500 on a set of rods. The engine which let go was a 406 based SBC( .030+ overbore with 6.125" rods I believe) with a 225 shot in a 3500lb 3rd gen car running 9.90's at 144+mph.

A head with a solid deck(3/4" like an AFR?) and top of the line studs are always good insurance too. Goodluck

Don't forget about that pesky fuel system.

 

I agree, the Eagle rods would be marginal for an app like this. Billet may be overkill though.

Rich Krause

 

ok do let me giet this right, lunati pro-mod connecting rods, JE pistons nitrous app., ngk tr6 .035 gapped, and thats it for a 300 shot? i dont need any pushrods or anythin else? also, ive been shopping around on prices and im looking at different things like the rods and pistons and im seeing a whole bunch of numbers and crap, i dont know that much about our engines. im certainly not considered a high end discussion guy, so how do i go out selecting the right piston and rod applications?

 

You need to involve your engine builder/machine shop in this whole thing if you are a relative novice at engines. The best way, in general, to get a rotating assembly is as a complete, bakanced unit. I have dealt with Callies a couple of times and have gotten excellent advice and service. You don't want to end up with stuff that doesn't fit! It can happen pretty easily. Normally, for example, the final boring and honing on the block isn't done until the pistons are recieved, in order to get the correct piston to wall clearance. Like I said, you may want to decide on the parts in conjunction with the person doing the machining on the block.

Anyway, JE pistons (or the SRP equivalent) would be fine as are the Lunati Pro Mod rods. We never talked about cranks, so what do you have in mind? If you are running a radical cam with stiff valve springs you should get a set of premium pushrods, but otherwise there is nothing specific about a nitrous motor that would stress the pushrods.

Rich Krause

 

If you say, Rich, that the best rods are not required, since they most often fail with tension, then if it is not a really high spinning motor (under 6700) would an Eagle or Scat Hbeam suffice?

Sorry Im intruding on your thread, but I figure you will learn as well from my questions.

 

o its just a stock motor, slp loudmouth exhaust, asp underdrive and alternator pulleys, and free mods, thats it. im just planning on throwing on a moroso CAI, jet hot long tubes, OR y pipe with borla xr1 muffler and maybe a lt4 hotcam and 1.6 RR's, and of course my nitrous and a stage 3 clutch. also i changed my mind about my shot i figured maybe 300 is kinda high so im going with a 250wet shot. and i guess thats a high enought shot for me. So what should i need for a 250 wet shot?

 

It's a gamble. The Eagle rods are decent. But a 300hp nitrous shot on top of a healthy motor is a lot of hp. There are no hard and fast rules. I know you don't need the billet stuff for what's being discussed here, but a street/strip motor may be harder on parts than a pure race motor. Not only do you make passes on the track, but every parts goes through many more stress cycles due to the street driving the car will see. The Eagles would likely be ok, but I would urge something a little stronger.

As far as 250hp v. 300, not a huge difference. Certainly, at a minimum, you would still need stout pistons. The other stuff would be a bit less critical.

Rich Krause