ShaneM

I meant the short block, just didn't type that lol

SceviourS197

I dont know what your dyno chart looks like, but most fi cars i see it begins to drop off after 5500-600 anyhow. soo why rev the nuts off it when you dont need too? if your racing you want to shift where your power dies off.

the parasitics loss isnt the problem. its the stress an strain by these supercharger designs. i've seen a 12 rib procharger shear off a crank snout. mid you this was being abused daily. the tvs blowers seem to be the most effecient way to go... then theres the free power of a turbo, which is the path i've chosen. with a proper tune with the tvs blower you can make NICE n SAFE power. same with ther turbo cars. if you are racing you dont need rev the nuts off. so why not keep the rpm down, an let that turbo or supercharger do the work...plus have you ever seen a misshift on these cars a 6800+ rpm? you cam phaser dont react in time from what i've seen. an then your in for a world of hurt.

candymanjl

I've been at 474whp on Kenne Bell's stock tune for over 5,000 miles now on my stock motor. still going strong! at some point I'm going to add water/meth injection and go up in boost just enough to hit 500whp then I'll call it a day until I build the motor

SceviourS197

whats your total timing full load?

candymanjl

full load near redline the highest I've seen is around 24 degrees. I'd say for most of the powerband the timing is around 20 degrees or less, it just depends on the rpm I'm at.

Stkjock

centri blowers keep making power the more they spin. my car made power right to the point the pull was let out at 6500 and the HP curve was still climbing..

as to shift point... you shift just past the peak power that way you fall back into a fatter part of your power band. if you shift to early the motor will fall out of that band

dkersten

OK, look at it this way: you increase the effective compression ratio in the cylinder chamber to get more power. That stresses the block and the cylinder. The power is transferred to the rods, which are mashed between the cylinder and the crank, so you are stressing the rods based on how much power the pistons are transferring and how much the crank is pushing back. The power transfers to the crank, so the stress from all 8 rods is on the crank. Now, regardless of what type of FI you have, the power at the crank is the same for the same amount of boost. Since the weak point in these engines is the rods, you look at the amount of power you get from a cylinder, which is based on the amount of fuel and air you can squeeze in, the displacement of the chamber, the amount of time you burn that fuel, and the ratio of air to fuel in the mixture, and send it to the crank.

The crank has to turn the flywheel on one end (or torque converter), and the pully on the other end. If you have a supercharger that takes 60hp to turn (at 6500 rpm), that is 60 less hp you see on the other side of the crank as well (at the flywheel or torque converter). Now the power travels down the trans, which has rotating mass that takes power to speed up or slow down as well as friction. Then to the driveline, which is the same situation - mass to turn and friction. Then the rear end, same story as driveline and trans. Then to the wheels where you have mass to turn also. So if you measure at the wheels, you are going from the power at the cylinder, to the rods, to the crank, and then you have to start subtracting the "parasitic" losses of the alternator, water pump, power steering pump, A/C, supercharger, transmission, driveshaft, rear end, and wheels.

A turbo has no parasitic power consumption as nothing from the crank drives it. It can produce some small amount of power loss due to restriction in the exhaust, which affects the ability to fit more fuel/air mixture in the cylinder chamber, and causes some minor power loss. Everything else is belt driven and takes power to turn. A typical straight lobe roots supercharger will take 50-60 hp to turn to make 9 psi of boost. A typical twin screw or centrifugal will take 25-35 hp to make the same amount of boost.

Regardless of which type you go with, the stress on the block, cylinders, rods, and crank are all the same, but your power at the wheels can vary by as much as 60 hp! Furthermore, with a lighter flywheel, lighter driveshaft, and lighter wheels you can free up even more rwhp without changing the amount of stress on the crank.

This is why you can have anywhere from 420-500 rwhp at 9 psi and still be "safe". In all cases, 9psi is putting the same strain on the rods.

However, having 100% traction when putting that power to the ground can cause an extreme amount of stress on the rods and crank, and even with 9 psi you can have a failure. If you build up the inertia in all the spinning and moving parts then suddenly put a load on them and you can generate many times the normal force they normally transfer. This is why drag racing is dangerous to your engine under any circumstances.

SceviourS197

i def believe that. 05 saleen, when they first had maguson superchargers, the intercooler was leaking, after the car had burned through all the coolant, it would put the cooling system for the intercooler under vaccum. this car dyno'd 200ish rwhp. i mean 200-210 that low. where as stock its been 269-275 average.

Norse1974

rotating assembly & block will hold 500hp-550hp with the right tune & set up....I was making a little over 500 with the bottle(150 shot) & ABUSED THE HELL OUT OF MY CAR!!!! D'aGASTINO tuned my ride. Was a guy named Scott Beers I believe.

jerjan

I'm running 14 PSI with methanol. Just under 550RWHP (dynojet) rev limiter set at 6000 for over a year and a half. She's still together!