Just gunna run it and hope for the best? lol this is literally a build from a bunch of spare parts from other builds that i didnt use. i could care less what the motor puts out or if it goes kaboom, i have two short blocks just sitting in my garage that i have nothing to do with

 

350 rwhp and a torque beast for basically machine work and gaskets? I wouldn't blow it up. I'd run it, get it tuned well, then sell it once you get the turbo set up built.

This 383 build should be a damn good engine for towing. When you sell it, convert it to Carb and Distributor for someone to stick in their older truck. That's what I'd do.

 

Thats actually a really good idea... now to find a tuner lol

 

although everyone days this setup is terrible what hp do u think stuff would start to crap out at? and the reason ive heard that claimer pistons are bad is because there bigger rings sizes and people dont pay attention to the size they are suppose to gap them and gap them wrong then crap out at high rpms because of the ring sliding up

 

It's not horsepower as much as it is heat and pressure and detonation.

Horsepower is directly proportional to BMEP (brake mean effective pressure) and displacement. So more pressure is more horsepower, and so is more displacement. Increasing bore and stroke on the stock heads also increase SCR (pressure) which increases power. But increased pressure also means increased heat. And the more heat, the more detonation becomes a problem.

One way to fight detonation is to tighten the quench (which also raises SCR, but in a good way). Another is to close the intake valve later, this is typical on larger cams.

But, when the cam closes later the BMEP is also reduced at lower RPMs. And less pressure means less power.

So with a higher SCR, later IVC (intake valve closing) event, and higher RPM's the power output jumps considerably without fear of detonation.

But, the larger cam will move the powerband up. The higher that any reciprocating mass reciprocates the harder forces are exerted. Throw on top of that high pressures and temperatures and the realization for much stronger materials for the rotating assembly becomes obvious.

I don't think your combination of parts is all bad. Just err on the side of caution with the tune and make sure your cooling system is running at 100%. A 160°F thermostat and tune the fans for it. You should be good to go. Keep the rev limit about the same as stock at most IMO too.

I'm in for the dyno results though. Honest guess here is 370-375 whp and wtq.

 

Thanks for all the input and help, learn something new everyday! thanks and ill keep yah posted!

 

Most of what hrc said, but its actually torque that is a function of BMEP and displacement, horsepower is a function of torque and rpm, or work done in a period of time (hp = tq * rpm/5250). Adding displacement and not increasing airflow decreases BMEP if you are inserting the same amount of air into the chamber as on a smaller displacement engine so when it compresses, the pressure is less. With the added cubes you will draw slightly more air than a 350 will due to more negative pressure in the cylinder creating draw as the piston moves downward for the last 4ci per cylinder (383 single cyl ci is 47.8, 350 is 43.7) but there is a limit to how much small stock heads can add, so yes just adding cubes will add a little power, but adding cubes is more beneficial if your heads/cam can add the same amount of required air and keep at least the same BMEP. Adding good heads to a stock 350 increases BMEP to a level high enough to overcome the increase in displacement of your lower BMEP 383 with small heads, hence why a good head/cam 350 will put down 400rwhp in an A4, and yours will be closer to 350rwhp. There is a guy on ls1lt1 with a similar setup to yours with an xfi280 230/236 cam that put down 370rwhp, and a cc503 is considerably smaller so I'm guessing 350 for you.

The danger for you is, like stated, heat and rpm. Heat from nitrous will very quickly break a ring land off the piston, regardless of how you gap it. Rpm and that heavy rotating assembly will kill that crank. The scat cast cranks have less failures than the cast eagle cranks, but they still happen 100000000x more frequently than breaking a stock gm crank, I have never read about someone breaking a stock gm lt1 crank even on 600rwhp engines, yet have read a few cast scat crank failures around 400rwhp.

Your combo will live a long healthy life if you stay below ~6100rpm and don't spray it. See what it puts down as is, maybe 350rwhp and 390rwtq is fun enough to keep you entertained, if not, put it in a truck or a B body, or sell it and fund a forged lightweight bottom end. Adding a huge cam will decrease power in the lower rpms, as stated above, which will cause you to be slower if shifting at the same rpm.

I would NOT run it for any amount of time without at LEAST a mail order tune. Someone recently installed I believe the same cam and ran it for maybe 20 miles and some full throttle pulls and cracked 4 pistons on a stock motor, untuned will either be lean or rich and cause too much heat for a cast or hyper piston.

One more cause for alarm in your build is the ls7 lifters, they have had TONS of failures and you will be much better off reusing your stock lifters. The other option is expensive morel or lunati link bar style lifters. A quick search for ls7 lifter failures will back this up. Also google scat cast crank failures just to see what is out there. It seems like any Chinese cast crank from the past 5-7 years have been breaking near the snout, before that people were fine.

 

Yeah, I used horsepower instead of torque because it is the end result. Like you said HP=(TQxRPM)/5252. So increasing displacement, all else being equal, will also increase torque, which will increase horsepower. But the dynamics of the air charge will change with added displacement, much like adding RPM's. The air will "pulled" in harder and faster at the same RPM's because of the added displacement. So a higher BMEP is likely even on lightly worked over heads because the air charge has more velocity due to the added displacement.

Agreed on the lifters too. I'm not sure I'd take that to even 6100rpms though. Maybe 5900 rpms??

OP, the reason a later IVC moves the power band up is because the intake charge has more time to fill the cylinder. Over lap uses exhaust velocities to scavenge and pull the intake charge into the cylinder too. The intake charge continues to fill the cylinder at higher RPM's because the velocity of the air can over come the pressure of the cylinder moving up. At lower RPM's this isn't the case, so an earlier IVC is better. Both, IVC and RPM, effect how much air flows into the cylinder and gets trapped by the valve. The more air in the cylinder the more pressure. The more pressure, the more torque, the more RPMs the torque is made at, the more horsepower. Of course, none of this is linear.