CNC

Hey Jim....
As you can see I still am trying to decide on motor combos....
Since I am basically starting from scratch I want to do it right. If you remember
I spoke with you on the 4th of July in Pentwater Mi. You can never ask to many
questions.....

Thanks
Randy

phatkat

This is very interesting , I too am in the same "boat". New 540-572,, boost or no boost. I 've learned alot from this thread,,,carry on. I already own a pair of 250 b-m's but looks like they should be for sale. Thank for the info. gene

JimV

iTrader: (1)

Dont get me wrong, the blower was great but I couldn't keep a bravo drive on it. With a 540 with a blower I was making over 950 hp and over 100mph. It got to the point where I couldn't trust the drive on long crusies after I beat on it the weekend before. I used to go thru three drives a season with the blower.


Randy, I thought you'd be boating by now.

Scarab28

Sounds like a good group to ask this question to. I'm currently runing an M-2 procharger on a 468 chevy, stock heads, solid cam, emi's, making 7 lbs boost.

The 468 is getting swapped out with a 540, 8.2:1 compression, dart 320 heads., crane 741 cam. Anybody got a guess as to how much boost the 540 will make using the same procharger components that were on the 468.

Hang Time 27

Scarab28, I'll guess that you drop the percentage amount that you increased in displacement?? But then that would be a guess.......

jimV,

Just checked out your website. Looks like you do create a little magic with that headwork.... on the one example you're "worked" heads only need .400 lift to get the same flow the stock head is getting at .700 ......sweet. No wonder that .650 lift number works so well.......... Is that example with aluminum darts??

I'm in the process of dropping that "little" red blower (in pic by "chambers" above) off my 540 to loose the heat and save my TRS drive. When I do resolve my drive issue this winter, what do you think your heads would do for me if dropped them on my current 8.9:1 compression(merlin315's), crane 741 cam, and dart intake?? I'm saddled with gil exhaust though.................sell me.....

Michael1

Jim,

The teflon will allow tighter clearances without scoring, which helps efficiency, but the same treatment can be done with smaller blowers, which could result in even higher efficiency. I say "could", because you really don't know without the compressor maps.

Now let's say you don't have compressor maps, but you do have all the blowers and a dyno available for testing. You're in luck. With a bit of work, you can rough out your own compressor maps. Just measure the blower outlet charge temperature, before the intercooler if there is one. Install blower 2, set the pulley ratio for the same boost at the same engine RPM, as blower 1 (may take some experimentation). Measure the blower outlet charge temperature on blower 2. The one with the lower charge temperature is the more efficient at that engine air flow rate and boost. You'll want to repeat these tests at various engine speeds. Higher charge temperatures are indicative of engine work going to heating air, rather than compressing it.

Hope this helps.

Michael

Michael1

The pressure ratio (boost) for centrifugal blowers is based on rotational speed. Therefore, if you use the same pulley system on the new engine, you should have approximately the same boost (may have some additional losses through the plumbing).

There is one potential problem, though. If the blower is undersized, you will end up running it is an area of low efficiency. This will result in more engine power going to drive the blower, and higher blower outlet temperatures. In the extreme case, you could end up in a compressor choke condition, which with the loss of boost, very low efficiency, and high outlet temperatures, would make the blower unusable.

Michael

tomcat

scarab28:

We had a customer do something very similar. Went from a 454 with stock heads and mild hydraulic roller cam to 502 with Merlin heads and more cam. Using the same pulley and RPM as before, his M1 went from 6.5 psi boost to 4.5 psi.

What you have to remember is that boost is just a measure of how restrictive your heads and cam are. Less restriction, less boost, but at the same blower RPM, the lower overall restriction to air flow allows the blower to use more of its energy for moving air as opposed to fighting restriction. So when you improve heads and cam, air flow goes up, even though your boost gauge goes down.

Now what's really going to blow your mind is what happened when we changed out his procharger intercooler for one of our supercoolers. With no other changes, including blower pulley size, boost jumped from 4.5 to 7.5 psi and the boat picked up 8.5 mph.

We have measured the restriction in the procharger intercooler, carb box and plumbing to be about 4 psi. There's only 1 psi lost going through the supercooler, so the blower has much more energy left over to move air. This extra air, however, is trying to get through the same heads and cam restriction as before so intake manifold boost has to go up. So when you improve air flow through the intercooler ahead of the intake manifold, airflow and HP go up at the same time as manifold boost goes up.

Michael1

Scarab28,

If I am reading these numbers correctly (gained 3 psi with your Supercooler, and Supercooler has 1 psi, total Procharger loss 4 psi), then almost all the restriction is in the Procharger interercooler (4 psi). That's a HUGE amount of loss in the Procharger cooler - half your boost!!!

What kind of intercooler inlet and outlet air temperatures did you see with the Procharger and Supercooler intercoolers in your tests?

Michael

wrenchman

I installed a Procharger M3 on my brothers 28 Warlock SXT( with a stock HP500). Installation instructions were terrible, and tech help was almost non-existant.Once I threw the book away, I finished the installation, while fabricating some hardware, without too much trouble. Once the boat was up and running (and properly jetted) it was a different story. The Prochager flat out runs. It idles just like a stocker, and runs like a bear. Just ran 103 MPH (GPS) I have Installed several other B&M roots types, but although they made good power, the Idle quality was always a pain. Its no fun docking with a motor that wants to die! Good luck with your project.