Crazyhorse

Dyno's in the 450-to-500 horsepower range now with his 454's in their current configuration. Could he be looking at another 100 horsepower per engine with a low-boost blower setup?

puder

low boost will work an dyou'll be fine.

i have forged internal in my engine but with 174 blower i'm making 550hp at 5psi.

dyno

Russ I had a 1994 454 mag that I payed a local so called go fast guy install a B&M 250 on, he did a nice job at least it looked nice. I could never get the motor to warm up it had cross overs without stats I think that was one of the big problems. It had a single carb that was blower preped by Nickerson but it was so cold blooded that it would hardly idle.after several weeks of the guy working on it and me taking it out on the weekend and proceeding to chew his azz on Monday morning cause it ran like crap he came to my house and picked it up vowing to return it by the following weekend running perfect. Well it had better my vacation started that weekend with a trip planned to Tourch Lake in northern Michigan. Well I put the boat in on Saturday AM full of gas headed out for a great week and the dang thing back fired and reverted......bad vacation had by all! he replaced the motor with a roller 502 that made 525 hp refunded the money for the blower and carb and I was happy. Knowing what I know now I would have bought a MSD ignition for it had the carb checked again by Nickerson and added some stats to get some heat in the motor and all would be well......in theory....

RLW

Your last sentence is exactly what I did to make mine behave. No theory about it. I run an MSD, my Nickerson Carb was sent back to Dean for an upgrade. Yes, it was a Nickerson (originally) and it did not work well. The upgrade was the ticket and his recommendation on my crossover setup was spot on.
It sounds like your mechanic is a standup guy for what he did on the refund. Not many of those guys around.
I see a motor like yours in my future. Keeps the insurance people happier not seeing the supercharger.
Thanks for the reply!
Russ

homan

that doesn't sound like that bad of a story and your mech. has honor which is very tough to find.

tomcat

Hey Cord:

I was going to give you $hit for your estimate of boosted HP. Obviously the 525/425 is 1.24...but you got me thinking and for that I thank you.

Blowerheads like to talk about density ratio. Looking at boost of say 5 psi on a 525SC you have a pressure ratio of (14.7 + 5)/14.7 = 1.34. But you don't make 425 X 1.34 = 570 HP, so what else is going on?

Temperature of course. Rough guess for the small Roots blower would be a temperature gain of 80F, so the temperature ratio would be (460 + 70)/(460 + 150) = 0.87. Multiply the pressure ratio by the temperature ratio and you get the density ratio.

1.34 X 0.87 = 1.1658

This is the increase in the number of molecules of air in each CFM that the engine takes in.

So to calculate the actual boosted HP gain

425 X 1.1658 = 495 HP

But wait, that seems a little shy of the actual HP, so what else is going on? The answer my friend is blowing in the wind.

With boost in the intake manifold, when the valve opens you not only have denser air, but the pressure drop across the valve area is higher. So for a while you actually increase the volumetric "filling" efficiency of the open valve. This only works if the exhaust back pressure is kept low. Which is why good exhaust flow is important on supercharged engines.

So if we increase volumetric efficiency by 5%

495 X 1.05 = 520 HP

Now imagine what a blower combined with good heads can do.

So what was the original question? Oh yeah...cast pistons. Detonation is the enemy. Run low boost, intercool if possible and port the exhaust. Forged pistons will stand a little more detonation abuse, but they're still going to fail. Must...stay...out of...detonation.

Red 230sx

Mcollinstn said above that Procharges "can usually be found pretty cheap too"...where would I look for one??

mcollinstn

Ebay,
OSO Classifieds,
HotBoat classifieds.

The 350MPI arrangement is going to be more difficult to find in its entirety. A procharger with SBC bracketry will be EASY to find, but some of the plumbing will need to be custom or ordered from ATI. The MPI mods will need to be done (ordered from ATI or sent to ASM).

You can cobble together a carb setup really cheap.

Crazyhorse

Dyno has hypereutectic pistons. He forgot to mention that.

Crazyhorse

I think Dyno should buy my 650 horse 509's with the B&M 250's so I can put turbines in mine. Jafo's been having an expensive influence on me,,,,,,,