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Quote:

Originally Posted by mggdoors (Post 4550413)

Altitude 3000. It runs stronger on top. Much stronger. Before after 4500 it would kinda take its time. Now gets there in a hurry. From what i understand my drives being 6 3/4 in the hole are hurting me. I have been running 26 bravo. They give bow steer bad unless trimmed pretty good runs flat but with rough ride. Never blowout ever. I have a set of labbed 27 mirage plus that dont take off worth a **** and blow out in rough. They were solid 6 miles an hour faster, boat felt light, rode smooth as silk in 3-4' whitecaps in havasu. Also they got to the top end Much Much faster. Like lightning. Im working with cutting edge now on some labbed 4 blade 30s that we are adding cup to the tip to air it out a bit. My buddy even said it looks like we have too much boat in the water.

The fact the boat feels stronger on the top end, would make me think youre making more power. Naturally, you would expect a smaller cammed, smaller headed, higher compression, dual planed deal to run stronger low end, but if she's stronger in the 4000-5000 range, I'd imagine you picked up some power that should net a better top speed. If you told me it was a slug compared to the old engines acceleration and upper rpm range, then I'd think your combo may be why it isn't pulling the speed number.

Makes me think something else was going on. Rev limiters issue, hull/setup limitations, etc.

The blowers should wake it up for sure. If in fact you could only pull a 26 bravo to 5100, I think 30's might be a bit steep, even with the blowers, if you intend to turn 5500ish wot.

Quote:

Originally Posted by MILD THUNDER (Post 4550446)

So put blowers on and ran it at 4.5 lbs boost. Gets up to speed like a pissed off honey badger. Problem is it hits wall at 5200. As did the last two builds. Im not accepting the whole not having enough power at this point. Have ran 25 std miarage 5200. 27mirage plus 5200. 26 bravo. 5200. All with mildly built 489 with vortec heads to blown 489 with eq320heads. Wtf is going on. Lifters or drive depth or distributors. Those are the only parts that are the same from build to build. Comp oem replacement lifters, pertronix dustributors licked at 30 timing, drive depth 6 3/4 directly below and 4 below pad. Do I nedd nose cones or something? Please advise

30 deg timing? I seriously doubt that is enough. I just dyno'd 2 blower motors and they liked 35 deg. They even fell way down on power at 32. Started losing power again at 37.

Quote:

Originally Posted by snapmorgan (Post 4554235)

30 deg timing? I seriously doubt that is enough. I just dyno'd 2 blower motors and they liked 35 deg. They even fell way down on power at 32. Started losing power again at 37.

Inthink you may have missed the point. The boat has had 400hp engines, 500hp, now blown at roughly 620-650. All engines turned all props to 5200. I am quiet certain through research we have an ignition issue or lifters. Crane 741 cams with matched springs etc directly from crane. We do not have rev limiters set. Im going to start with coils as research tells me that the pertronix couls tend to fail. Btw I have a pair of labbed 32 on way and Im willing to bet the rpm will be same or close

I think we got this nailed down. Upon inspection and doind proper voltage load test I determined we have low voltage to coil and ignitor. Unloaded it shows 11.5 volts. Loaded 6.54 meaning we have a resistance wire somewhere. We wire relays in tonight and run it again Sunday with 32 labbed cutting edge props. Will keep you posted