The plan is to seal up those two holes you currently see and to drill 4 new exhaust holes in the stock bravo location in order to have straight thru hull exhaust. I'm not looking to get the whole QandQ set up. I found two sets of used tips for a decent price but just don't know how they would react to power. The tips have the welded baffles in them. From what you said on your buddy's boat I think I may pull the trigger on the tips.

enough said on those tips, I just bought them.

I had to glass up the existing exhaust holes on my Donzi project and raise them 4" for a proper fit. I have raised port exhaust heads and using the 2" taller 496 risers and a 1" o2 spacer so I am way taller than stock! I also used the aluminum 496 exhaust and be very watchful for signs of reversion....... I would use the turbulator plates for sure as I had reversion issues using no turbulators and stock height risers..... Good luck with your build! TBF

Hope you didn't buy the ones with the swirly thingies in them, as they will create backpressure for sure. Had a set of those made by Gil on my old 454, and lost about 3 mph with them - and this was on a mildly warmed over 454 with stock oval port heads and stock exhaust.

Sorry guys, got away from this thread for a while. Have to figure out how to get email notification for new posts.

Budman - those are exactly the ones I now have but made by Corsa instead of Gil. I figured I could just cut the swirly baffle out.

TBF - I have the 10in risers and planned on running without turbulator plates, actually, I don't even have them. My cam is on 114 lobe sep angle so I"m hoping it'll be ok. I'll do all the checking on the first run to be sure.

To all - Dyno time is almost here for my engines, just waiting on fuel pumps then set up time. Can I run the alum 496 take off exhaust and risers dry for dyno purposes? I would like to have more accurate number with MY setup rather than using the shop headers.

Got the twins back home.

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This is a sheet on one of our oval port, pump gas combos. It's our 625/625 engine.

In a nutshell, 498" 4.320" bore 4.25" stroke, 6.385" rod. Early 049 port heads, 2.125" intake, 1.72" exhaust, porting on the intake side only.. Custom Hyd. Roller cam. Single 850 carb.

Oval port heads work really well and provide exceptional fuel economy. Look at the BSFC numbers. Note, this engine was run on oxygenated fuel it's probably 10-20% ethanol up here this time of year.


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Here is one we just finished dynoing a few hours ago. It's a 550/550 we sold to the customer in complete kit form. He did all the assembly, and did a excellent job.

460" stock stroke, 4.280" bore. Mild cam, hyd. Roller, 6.385" rod, it was a street engine and had dual 4bbl Eddies. This engine is running 91 octane Non-Oxy fuel. Notice the BSFC is much leaner and more efficient.

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Oval port heads should not be underestimated. They provide excellent horsepower, torque and economy if the combination is put together correctly.

I ended up with rectangle port Race Rites so it would match the GM intake I reused. I may have given up a little here and there with my build between port shape and compression but most of all I want a reliable mill that will work and not need to tinker with ALL the time. Plus I've done so much to this thing this offseason….I'm tapped out.

I'll get the dyne sheets posted this weekend. For now I've been rigging the engines in the garage. Check out the ultimate custom remote oil filter bracket along with the custom oil cooler mount. Those zip ties are just for the mock up. Got the idea for the oil pump off here as well.

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I use that same Harbor Freight pump in pic 1 to draw the oil out of my engines. I installed a 3/8" barbed hose in the drain plug hole in the bottom of my oil pan prior to rigging. Both of my engines are Y'd off of the on suction side with an inline ball valve to each. I have the pump mounted in the front of my bilge and throw a switch to do oil changes. 2 engines take ~8 mins. It's pretty slick.

Rookie-thanks for that idea. I was thinking of plumbing the engines together like you but haven't worked it out yet. Now I know how. What fitting did you use in the bottom of pan? You said 3/8 hose barb but what's the threaded side? Do they make 1/2x20 to barb? I almost bought the kits but figured there's a "hardware store" way