Dustin came in on Sunday (the dude is a serious workaholic), and tweeked the PCM some more... still not finalized.

Stage IV dyno graph:

Chris

Hi Chris,
Good reading as always. In the dyno shot, It looks like Dustin is using your EFI, throttle body, and intercooler with his 4.0. Am I correct? I understand he's probably doing that to "package" out his various "stages". I would think his aftermarket throttle body on the 4.0 would flow more cfm than the OEM Merc unit, wouldn't it? So there's some HP there, and you could always swap out pistons for more static compression (7.5 to 8.5/8.75).
Best Regards,
Steve

The 4.0 Throttle bodies are beast and high on the cool factor. Beautiful pieces and worked very well with a dual IAC setup which probably won't be required with the mild cam you're using.

I'm beginning to get a bit concerned with the rotating assembly on that setup
You may be tuning the 540 setup pretty soon

Great numbers!

Steve... correct... stock throttle body and innercooler...

The innercooler has been modified to flow more water than the stock setup. This required a seperate pickup for the innercooler.

Dustin has already flow benched the stock throttle body, and says it is more than adequate for the hp we are making. The stock air cleaner is disfunctional at this point, and costs the motor nearly 20 hp. Dustin is working on a better flowing air cleaner.

The stock bottom end is extremely stout on this package, and has been used in making over 1000 hp.

The limiting factor we are running into now... and you can see it at 4700 rpm on the dyno chart ... is the restriction in the heads. Dustin is considering making the Stage V modification, a CNC port job to increase flow. The motor then would require less boost per given horsepower. At this point, boost is stacking up in the intake, and not making it to the pistons because of cylinder head restrictions.

At some point in the future, I will probably be building a 565 bottom end to put under my existing parts. (Dart 9.8 block, 4.6 bore, 4.25 stroke)

Chris

I would agree on the head restriction as that is what I referred to earlier on (too much blower for poor flowing heads)
Next restriction is possibly right around the corner...

I guess we'll just agree to disagree as to the bottom end

A stock GM forged crank is in no way designed to support 1000hp, let alone with another pulley on the end of it

Maybe I misunderstood the package but I thought this was just a 600SCi motor.

I just added to my above post while you were responding.

Heads are definately the restricting factor.

The 4.0 makes aproximately 35-40 more horsepower than the 3.3 in this application, while spinning slower and putting less stress on the front of the crank than the 3.3, and creating less heat.

I am not claiming that I know about the crank or bottom end ... just repeating what have been told by Dustin Whipple and Eddie Young.

It is a 600sci.

Chris

Now your talking

I have abused Gen VI blocks in the past and they are surprisingly very strong but they also had good Crower internals and were studded.

Now ask Dustin or Eddie if they would warranty a 1000hp blower motor with a GM502 crank. I think I know the answer to that

Your going to be running very strong when the it's all done. Keep the techi info flowing.

Thanks,
Dave

Dave,

Thanks for the info.
I will definately keep the info flowing.

Interestingly enough... we had a hard time figuring it out... this is not a Gen VI block, but rather one of Merc Racings new castings. Two piece rear main seal, Gen 6 front cover, extra webbing, clearanced for a stroker crank..etc ... Bob Maderia helped us figure this out.

Chris

Yes Chris,
A new and strange block for sure. It's GM's (not Merc's) latest Gen VI now dubbed a Gen VI/Gen IV. I recieved one this Spring and looked at it for a couple hours trying to figure out what I had received. The fuel pump boss and clutch linkage had me completely bewildered as well.
I measured everything I could imagine to see if it would fit where it was going (525EFI) and everything measured exactly the same as the standard Gen VI block sitting next to it. Only difference was the fuel pump and clutch linkage provisions. No extra ribs or any strengthening additions were visable. Just a 502 block that people can now used thier Mk-IV parts on.
The main improvements appear to be over a Mk-IV blocks which the late Gen VIs had already implemented.
They are 1 piece seal units but can use a 2pc adapter to fit a Mk-IV crank if you so had to use one. Merc only uses a 1 piece seal arrangement at this level.
At the 850SCi level they go to a Callies 4340 forged unit (for a reason ). They get $10k for it on Mercruiserparts

Glad to see someone else ran across this seemingly odd block
Slapped a fuel pump block off plate on and was on our way

Dave

Update:

The motor made 905 hp at 6100rpm, and 855 ft/lbs of torque.

This is with a stage IV setup: reprogramed PCM, Whipple cam, 4.0 supercharger at 13 lbs of boost.

Dustin feels that boost is once again stacking up in the intake manifold, and not getting into the cylinders, and that the heads are now the limiting factor in the equation.

The next step is stage V modification... ported cylinder heads. The heads on the 525, 600 and 700 are all the same, and specially designed for their closed cooling system. Dustin feels that with opening up the heads, he can produce the same horsepower and torque with 2-3 lbs less of boost.

Of note, Dustin discovered that once this motor starts flowing enough air to get over the 750hp mark, that the stock air cleaner is reducing power by over 20 horsepower. He is in the process of building an new billet air cleaner for 600 and 700 sci motors that will be a nice addition to any 600/700 motor owners looking for some added bling and performance.

Chris