Formula 311, TRS boat currently set up for 502 MPI's, CMI exhaust. The boat typically runs about 70-71 MPH in a choppy water given room to run and good air. 4700 RPM with 27P Mirages (not Pluses). The 502's are under 500 hours and I just did the heads on the port engine due to gasket seepage issues that needed attention. Both show about 160 PSI across the board and run very well.

I have purchased a complete valvetrain package from another member on the board consisting of Crane 621 cams, Crane long travel OEM-style lifters, springs, retainers, Crower stainless rockers, ect... everything needed to do the valvetrain. I'm thinking of ditching the entire top-end (088 heads, MPI set up, etc), and moving to EQ 320 heads set-up by me and my local cylinder head guy, and dual-plane Air-gap intakes and 9022 Holleys. The current fuel pumps should work, but if recommended I'll redo all of it. I plan to keep the Delco distributor, but changing out the modules is probably needed.

I would like to see a solid 75 MPH out of the boat with this combination, perhaps a touch more.

I have tried to digest as much information on EQ heads, and since I'm in salt water I think this is the best course to take. Everything I've read on similar projects seems to say 570 HP or thereabouts is a relatively attainable goal with the set up? What do you guys think?

TIA,
TZ

That was a good deal on that package.

I think you could obtain your 75mph goal without the new heads and keeping the MPI setup.

Griff,

Yes! It was a definitely a good deal. I priced most of the big ticket items and came in well under .50 cents on the dollar.

I like the idea of stepping up to a better set of heads. I would need to go through the starboard engine's heads anyway so I thought I'd step up while I apart. If the boat goes faster than the goal, that's even better. With the MPI I think that even with mods (following Smitty's threads on them) I'll still be short on taking advantage of the cam. I'm thinking that peak would run around 5400-5500. Does that sound about right?

I've entertained going with a Sniper set up to keep some sort of fuel injection/ease of use (compared to the carb), but I think carbs will get me there more easily. That's my thought anyway. I'm open to any and all suggestions!

If you go with the new heads, then I'd go the carb route. I don't think the MPI set up will support more than about 500hp, at least not without a lot of mods. I think you'd be close to 500hp w/o the heads and would gain the 4-5mph you were after. The new heads, intake and carb would probably make around the 570hp and you'd probably be in the high 70mph's.

buddy had warmed up HP 500's in a 311, TRS boat making probably 530-550 HP, spun Mirage 25 plus labbed props to 74-75@5400.. with solid 600-625 HP the same boat went 80. spinning drives in, make sure you add HS to keep it going straight..

I've been running through some dollar figures (never a good thing), and just in parts for the heads alone (castings plus valves and everything needed to assemble) I'm approaching $3.5k. That doesn't include machining on the heads not does it include anything else on the top end (carbs, intakes, etc). My port top end is fresh and for minimal money (in comparison) I can have the starboard side freshened up as well. I would more than likely be dumping the EFI because it just won't get the RPM up enough to really take advantage of the cam without a lot of modification (at least that's my understanding... Griff, I know you said my goal is possible with the EFI... it's not for sure off the table... just need convincing with that thinking). I may even look to some other EFI alternatives though that would be defeating my current argument.

Staying with the 088s, am I really leaving a lot on the table? From a cost standpoint, meeting my 75 MPH goal with a lot of what I have sounds like a good direction to think about.

On a side note... I know I can sell the EFI and related parts and heads to recoup some costs if needed.

Am I basically building a HP 500 clone at this point with a little more cam? And is 500 HP a side enough to get a TRS 311 into the mid-70s?

I think I'll have to keep my 311 tied to the dock! :-)