What limits the amount of boost?
 

I had to install a new inter-cooler on an HP 500 with a M3SC Procharger. The only one I could get was the same model (AW 504) but it had a larger diameter inlet and outlet. After making some adapters it installed exactly the same as the old one. Problem: I noticed the fuel pressure starts to ramp-up even before the gauge shows any positive pressure, and the boost now goes well beyond the 5 lbs. that it used to make.
Could it be that the larger ports on the inter-cooler are causing this change?

Re: What limits the amount of boost?
 

What / where is your boost reference line hooked into ?

Re: What limits the amount of boost?
 

your wallet :D i read where phil lip****z told a customer that the boost gauges was like a bank account when your making boost your spending big coin :evilb: or something to that effect. :eek:

Re: What limits the amount of boost?
 

My wife slapping me in the back of the head saying too fast too fast. :D :D

Re: What limits the amount of boost?
 

did you contact the company you got it from, what did they say they im sure your not the opnly one this has happended to. may be its and improved unit. how much boost are you making now?

Re: What limits the amount of boost?
 

The answer is Yes. You reduced the restriction to air flow so more of the compressor discharge pressure is making it to the carb box, instead of being used up fighting the restrictions. Fuel pressure regulator is referenced to the carb box so it is ramping up sooner. Intake manifold boost will increase by the same proportion. All this is accompanied by an increase in air flow and HP. It's all good.

Re: What limits the amount of boost?
 

How big of a pulley you can get on the bottom and how small of a pulley you can get on top..........oh yeah, and how much you like to pay for fuel...... :p :drink: :D

Re: What limits the amount of boost?
 

......and broken parts.....

Re: What limits the amount of boost?
 

What limits the amount of boost?

Simple anwer: MONEY ONLY MONEY.

Re: What limits the amount of boost?
 

If this is where the pump reference and boost guage is hooked up to, I agree with Tomcat - it provided more effeciency and better breathing to you. Good move !!!

Now, that being said, my boost is limited by the size of my coffee pot. :drink:

Re: What limits the amount of boost?
 

It all comes down to how much cylinder pressure you can produce at any givin rpm and load without detonation. Not just intake manifold pressure, that is mearly a measure of restriction. You can have a motor that makes more hp with 5psi then another with 20psi if it moving more air and making more cylinder pressure. Cylinder pressure is power, the amount of air you are moving. I would have a profesional tunner tune it if you are asking this question. As it will save you a lot of money in headaches. You can run an amazing amount of power through a stock bottom if careful attention is payed to the tune.

Re: What limits the amount of boost?
 

Thanks guys,
The boost reference line is connected to the rear of the carb. enclosure. The Procharger tech said the larger ports would have no effect. I have learned not to reley on them for too much help! This is a stock HP 500 so I am a little concerned about how much is too much. I was seeing 8 lbs. boost and 15 lbs. fuel pressure when I signalled the driver to back down. Unfortunately I did not see the RPM, but I beleive it was between 5000 and 5500 due to the fact that that we just started trimming up and it was a relatively short blast. If I leave the set-up as is, I will certainly due a plug check, to see how she is burning.

Re: What limits the amount of boost?
 

I thought my boat was the only one with a" B*tch governor"

Re: What limits the amount of boost?
 

If you are seeing increased boost you should also be seeing an increase in engine RPM due to more boost equals more power produced. Less restriction in the intercooler most diffenetly will give you more boost or better air flow.

Jim

Re: What limits the amount of boost?
 

The inter-cooler is the same model, just different size ports. I assumed the cores would be the same, so I am surprised that there would be so much more flow.( BTW Tomcat , if your following this thread, this is the inter-cooler I got from the guy you reffered me to this summer.) I would expect more RPM with more boost, but I am surprised that I got such an increase at that RPM.

Re: What limits the amount of boost?
 

wrenchman: Glad the connection worked out.

To go from 5 to 8 psi is too much to be just from the IC swap. Two things come to mind. Maybe the air side of the old IC was blocked with dirt, belt fluff, etc., that was sucked into the compressor, Procharger doesn't use a filter. Also wondering if any other changes were made to the engine or exhaust that would have made the engine more restrictive, therefore more boost reading.

Re: What limits the amount of boost?
 

I highly doubt you gained any boost from simply changing the inlet and outlet slightly on your innercooler. I did pressure drop test on a run of the mill aw504 on my boat 4 years ago and it was less than 1 psi,closer to 1/2 psi. Did you tighten up the end of your boost reference hose or tighten your belt? It is common for the 8 rib drives to slip unless runber band tight,especially if you run 4" or less upper dia pulleys. I had to change mine to 12 rib drive as it would make 6psi sometimes then 8 psi,after changing it boost was consitent,Smitty

Re: What limits the amount of boost?
 

Wrenchman
BTW what carb are you running?

Re: What limits the amount of boost?
 

Anytime I go from 5 PSI to 20 PSI I make HUGE gains in power......regardless of what type of engine! :D

Re: What limits the amount of boost?
 

JRYAN26, I am running the stock holley (800 CFM ?)
Tomcat, The old IC was clear and there were no changes made to the engine. The engine was out of the boat when I installed an IMCO ext. box, then re-installed but no other changes made. I was wondering what effect it would have if the braided boost ref. line had a restriction, IE.kinked or compressed?
Smitty, I am running the 12 rib. Prior to this, the setup ran very consistant 5lbs boost.

Re: What limits the amount of boost?
 

Based on the info your giving us it shouldn't be hard to tell if your actually making more boost for some reason or if your just seeing boost that was always there. Does the boat accelerate any faster,doers it rpm higher or pull more prop than before? If there is a noticable difference than some how you did gain boost,if it feels exactly the same but your just seeing more on your gauge then it was a restricted fitting or loose connection for your boost gauge reference hose,Smitty

Re: What limits the amount of boost?
 

In this instance - wouldn't we be more concerned with intake boost vs boost before the carb ?

Boost before carb is effected by restriction of carb.

Ahhh, screw it. Basically, I'm getting confused I think. Doh !If motor is not detonating, your tune is correct, and you are making more power, that is all that matters. LOL !!! :D

Re: What limits the amount of boost?
 

SB,
My boost gauge line comes off the intake. My boost reference for the fuel pump comes off the carb. enclosure. The strange thing is that the fuel pressure seems to be ramping up even before the boost comes in. At 3500 RPM cruise(no load - no boost) the fuel pressure is up toabout 10 lbs. At idle it is still @ 7lbs.