LAKE EFFECT

I think the Whipples would be a good combo, I'm not sure what HP they are rated at on the 525. If its anywhere near 750hp, then your goal should be very obtainable. Procharger, back in 2002 with my chargers on a 500hp rates the hp @ 710 with 5psi. I have better heads, bigger cam and 7psi, so I would claim 750hp if someone asked.

The Whipples are going to make better torque down low, and pull the bigger prop you will have, which will give you better drivability at slower speeds then I have with the Prochargers. Probabally also stressing the drives a little more as well.

My boat being a 98' should have a deeper X dimension then yours, I think Formula raised it at least 1" in 2000 or later. I have a 12" extention box and a 1" shorty drive(both IMCO). I dont have a comparision with out the boxes, as I bought the boat with them. Axapowell does though and said there worth 1-3 mph. If your not trying to ring every last MPH out of the boat, extention boxes probabally wont be worth the effort. Boxes should add stability at speed to the boat, so if the labor and money arent a big deal put them on, they do add a cool factor to the back end as well, take Dave's advise on that one. They have'nt affected my family boating either.

Learn from everyones mistakes as much as possible, because melting a piston in middle of the season isnt good for family boating. You have a great combo to start with, Whipple will give you a good tune for the EFI, so that will take a lot of guess work out of the equation. Extra engine monitoring cant hurt. Fuel pressure, water pressure, oil temp, and boost will all help keep things in line. You have XR's already, which is the best place to be when starting on this new adventure, but keep in mind XR's can and will break.

As I have found out, props will make a huge difference. I keep on hitting new milestones with my combo by just changing props. I have more time than money invested in my prop setup, hitting my best speeds with used Bravo ones. 97mph with 1.36 drives/32's in '07, 102mph with 1.5/34's in '09, and 107mph with 1.5/36's in 2010( raising my rev limiters to 6000rpm).

Set the boat up right, dial it in, and you should have no problem being one of the few with a Fastech to post a triple digit thread. I would of earlier, but a short boating season and money slowed me down(mostly the money).

LE

Wise A**

Do you guys think the extension boxes help your speed, or just help in stability at high speeds?

LAKE EFFECT

There suppose to do a little of both. I bought my boat with them already on so I couldnt give you a good opinion on a Fastech comparison.

Hows your 312 handle high HP now? any chine walking? My 353 seems right at home with a lot of HP, but the smoother the water, the more likely it will chine over 85/90mph. sometimes scary, but always manageable with thottle, tab and trim.

LE

johnnyexcal

hey le---- who initially built those blow thru carbs ------- would like their knowledge to start with instead of gambling ------

LAKE EFFECT

I bought the boat which is an original HP500 boat with one blown engine. The previous owner threw a ton of money at it, but was paying a mechanic to do all the work, this kind of setup is definitely a do it yourself and have some knowledge or your gonna go broke kind of thing. The boat came with the Prochargers, IMCO boxes and drives, and MSD's.

Machine work on the blocks and heads were done by Gellner and Victory. Dean at Gellner's helped me greatly with clearances, oil system and balancing. I did all the assembling and rigging. I tried to prep the original HP500 800cfm carbs for blow thru, which in hind sight wasnt a great idea(caused me a motor with 2 melted pistons), Ray at Victory did the cylinder sleeving on the one bore that got beat up. Since then I bought purpose built 750cfm HPseries blow thru carbs, monitor air fuel ratio's and EGT's and have had great success with the setup.

I'm always willing to help someone trying to do a carbed blow thru setup, so if you have any questions give me a call or PM me. Being that your local should make it easier. If you boat out west by the islands I might of already talked with you. After around 10 beers I give up all the secrets to the universe.


Scott 216-214-2462

LE

Apexwarrior

A whippled 525 should put out about 750 hp. I'm thinking I'm going to leave the drives as they are and see what I have. I don't need every last mph and I'd prefer not to put money into drives that may blow up on me. If they do blow up, then i'll probably redo them and set it up properly. If I'm at 90 or more, I will be happy.

johnnyexcal

thanks scott - i do all my own machine work and builds - i just wanted to know who you bought the purpose built carbs?? from so i can be within a generous starting point for air fuel -
yes i also monitor everything now -gauges galore - i've talked with you before - i own the all black 24' excalibur - thanks for your input=
johnny

LAKE EFFECT

The boxes arent going to add any reliability to the drives any way. The XR's are the strongest stock Bravo you can start with, but there are all kinds of smaller upgrades that can be done to help prevent failures. The Bravo drive is also very a simple drive to work on with some specialty tools. The guys at Max Machine Worx in Arizona have helped me out greatly with tech advise, and now I do all my own drive work.

I think you would be better off doing some upgades on the XR's before they blow up, because once they do, they just dont seem to be the same. Heres a couple recommendations:

If you dont have the newer swept back XR, the upper cap is stock Bravo and needs to be replaced with a Billet cap with 7/16 studs(very important on the LH rotation). The upper clutch shaft and collars are also easily upgradable. Hard shimming the input/yoke shaft keeps the pinion gear and bearing stable. Max also can upgrade the drive gear tower bearings to prevent deflection(I havent done this one yet). The XR lower already come with the big prop shaft and billet prop carrier. You can upgrade the vertical shaft and hard shim the carrier, but the upper upgrades are far more important.

If spring is when the Whipples are going on, I would split the upper/lowers and send the uppers to Aaron and Jason in Arizona. Do the upgrades mentioned and you will be far less worried come summer time to run the new found HP. If you can do the work yourself you can save the labor.


http://www.maxmachineworx.com/


LE

LAKE EFFECT

I'm assuming you have a good drive shower already, if not put those on the list as well.

LE

LAKE EFFECT

Sorry for the bable, I kind of thought that after typing the book when I re-read your post. Anyway, my carbs are from PC carbs in Ontario CA. but he has since stopped making blow thru carbs. When I inquired why, he said demand was dropping?? I did talk to CSU carbs in Fontana CA. as well(looks like all these guys know each other) and it looks like he is taking all the blow thru business. CSU does most of the same stuff PC did, but he claims more R&D and some other stuff with the power valves and jetting. I do have a buddy who built a Procharged blow thru 347cid Ford and he likes the CSU carb.


http://www.csucarbs.com/index.html

http://www.performancecarburetors.com/index.php

LE