Hoping to get some feed back! I have a 03 38 t/s with 575's. I recently put intercoolers on (whipple) and was told that in addition to helping with longevity of motors and helping to prevent detonation, i would see a minimum of 50-75 horsepower increase. I was running a 4 blade 33 lab finished prop and the boat would do a solid 89mph @ 5100rpms. After the install ($10,000 later) i could no longer get the boat on plane with ease (sometimes have to start and stop a few times). Props wash out when coming out of hole. But when boat is up and running im not seeing anything over the same 89mph but now at 5300rpms. So then i was advised to go spend an additional $3000 and buy a set of 28 pitch 5 blade maximus props to fix my planning problem. Well it fixed the problem and now im running 86 mph@ port5250rpms,star5450rpms with all the same conditions (water, air, fuel, weight). My frustration is that i spent good money and haven't seen any differences in the boats performance. I've had to change props to get boat on plane and have lost 3mph after all the work done and am running the boat at higher rpms to get the speed. Any advice would be greatly appreciated!

If all you did is add inner coolers than you are probably only seeing 3 lbs of boost or so, thus rendering your rig with less power than you started with.
Now you need to over drive your superchargers probably 7 %+ (smaller top pulley) in order to overcome the restriction you now have with your inner coolers.
You will see instant 90s gps getting back to your original boost level of 5 or 6 lbs.
Then you can get back to a prop that works for your hull,I will guess you will quickly hit the rev limiters and will need to run a larger pitch.
Good Luck!

check with a guy on the board called tom cat . I think he has a company called R-Tec that deals with intercoolers

Sorry, i did have the pulley system changed as well. Im running 7 lbs of boost! Dustin at whipple modified the computers and he said the rev limiters are set at 5600. Thanks for any help

That is odd. My '02 boat w/ rebuilt 575's that now have roller cams @ redline at 5600. It will run 94 @ 5550 w/ bravo 32's that have been flat pitched. After rebuild, they have 630 hp ea. You should have MUCH more hp. I still haven't totally dialed mine in yet.
Have you consided that the motors may need work now? Something is wrong w/ your set up.
Maybe something internal has let go. You should be seeing at least 96+.

Are your props modified 34's? If so, they have a "unique" geometry all thier own and have had planing issues. Most decent props shops can fix that.

Did you shorten the drives? If so, TG's are faster w/ the drive in the water more. (as per Tres Martin)

It doesn't add up. If all you did was add intercoolers to exact same props/drives/boat then you should not have a plane issue, and you should have more speed.

Bill, the motors only have 180hrs and i had leak down test performed 40hrs ago. Everything was extremely tight. The 33's i was running are lab finished. I did not shorten drives. They have always had a 1inch spacer. Im running xr's with its and sportmaster lowers. Nothing has changed. I also ran 32 p 4blade bravos (not labbed) before when i dinged my 33's and prior to the intercoolers, they never blew out either. After the intercoolers, the 33's blow out the worst, the 32's blow out but not as bad and the 5 blades don't blow out at all! I must be running more hp since im running higher rpm's correct? Thanks for any help!

How about getting the blowers looked at. They NEED freshing by 180 hrs.
Blower shop! They'll upgrade the bearings and seals, more importantly - they'll check the rotors for clearance and balance. One of my blowers was new and after 100 hrs, I needed new rotors. The ones I had were warped and out of balance. Likely that way from factory. Both had teflon tips installed to make more efficeint. My reasoning is: The blower could be kinda weak now and adding an intercooler adds more resistance. You may want to rebuild your blowers or better yet, install a bigger blower to compensate for intercooler's added airway resistance.

As for props suddenly blowing out - that makes no sense.

Bill, i have not had my blowers looked at but probably will. I have been told by many that the blow out is caused from the additional torque added to the boat. Thanks for your help!

Doubletake,

Did you ever get this resolved or figure out what the cause was?
I'm going to add intercoolers soon on my '02. Hope to avoid any gotchas.

Thanks

Before doing that I would talk to some reputable builders - Like Joey Griffin.