87MirageIntruder

It started with the stock 2004 496HO with 400hrs on it. Top speed was in the low 60s (MCOB boat).

It now has Scat rods, Wiseco forged pitons .030 over at 8.9:1, Cometic MLS head gaskets, Raylar rockers, Raylar BP211 blower cam, Comp valve springs at 130lbs seat pressure, and a 3.3L Whipple at 7psi. It was balanced too.

I fired it for the first time Saturday. It sounds pretty good. Hopefully I will get to test it out in a couple weeks. I have a 30p bravo and a 28p 5 blade cutting edge to test out. Bravo drive has a 1" spacer.

Any guesses on top speed? I'm thinking roughly mid 600s for HP and high 70s for speed.

87MirageIntruder

And to add just for everyone's FYI, here are some pics of the 400hr main and rod bearings that came out of the original sealed factory engine.

IGetWet

Should definitely wake the boat up. You’re going to like it. Tuned correctly I’m thinking you’d be over 700hp.

BBYSTWY

700 HP should easily put you at high 70's even 80 propped right.

87MirageIntruder

Update: I got a chance to run it on the lake. Air temp was low 50s, lake temp 49, 1,800' altitude. It ran great, no leaks or issues so far. My AFR gauge was around 13 at idle, and was at 11 at 3k RPM (rich). Then we stopped to look over the engine before running it up to speed and my AFR gauge stopped working. Rats. So much for the tuning and data logging for Whipple. Knowing it was rich I went ahead and ran it up to full throttle for a couple 30 second bursts. It was glass calm and RPMs with the 28p 5 blade 15" Cutting Edge prop were 5000-5100. We saw the GPS hit 75MPH. Not bad for a first test and knowing it is running too rich at the moment. I've got a couple replacement O2 sensors for our next time out.

While running the engine at high RPM the water temp ran about 140, 150 tops. The oil temp (before the cooler) hit 240 on the first run and 220-230 on the second run. I'll have to watch those oil temps, especially as the lake temps rise in the summer.

So, with some tuning and prop testing I'm thinking upper 70s should be no problem. I've got a 4 blade 30P Bravo to try also.

snapmorgan

iTrader: (2)

I had a 28" Advantage MCOB which is a very similar hull. It would run 80 with 700hp turning a 28P labbed Bravo 1 on the rev limiter.

nitro/max

Those heats like chop. The Heat will run faster in chop than glass water. Had 03 heat with a 525 for 13 years it was good boat. I do miss it. Boat less now for few years.

87MirageIntruder

Yes they do like chop. It was glass calm when we did the first test ride and the elevation was a bit high so I know this boat will go faster. Especially when we lean it out like it should be. I'm thinking 78mph easily.

Darbs

Does you heat chine walk at 70 + with your new power? If not would you mind telling me how far your prop shaft is below the keel? I have a similar Power in my heat with some chine walk. Wondering if a spacer will fix it?

87MirageIntruder

I'm 4.5" below the keel. Running a 5 blade cutting edge propeller 28p. I have a 1" spacer on my bravo drive. No chine walk at all over 70. I have trim tabs but don't use them, keep them up. It's stable even when playing with the drive trim.