Quick HP upgrade

[donzislsman]

I need some help. Within the last week I just read an article concerning increasing your horsepoer using a very simple process. The article claimed it was new, but I am sure by how simple it is it can't be. It involved a stock 500HP EFI and the flame arrestor on the fornt of the block. Anybody who has ever taken the flame arrestor off will know that there are two intake holes underneath the arrestor. This article talked about cutting the middle out of the two holes and creating a single large hole. You then replaced the flame arrestor with an upgraded one(they had a specific brand listed and I didn't think it was K&N becuase that is what is already on there). I don't remember the amount of horsepower it promised, but it wasn't much but we don't need much. It had to have been in Boating, Powerboat, one of the big ones, but I can't find it and it is killing me.

Also, if anybody has any experience with this I would certainly appreciate your input. What I need is about two or three miles per hour on a '01 Donzi 33ZX with twin stock 500 HP EFI's currently running about 81mph on GPS. All help is appreciated.

Barry

[BigGrizzly]

It's not just that simple. yes it will give you hp but on acceleratiom. 2->3 mph is going to take more than a little HP that this will provide. Remapping the ECU will need to be done also. the best alternative is to prop it and get away from stock type bravo one props, which by the way are the slowest on my boat.

Randy

[MXRoadster]

You might be looking for the July issue of Family & Performance Boating; it has an article about bolting on 65 HP for the HP500 EFI. It does take a little more than cutting some metal and adding a new air filter.

[donzislsman]

Thanks for the help gentleman. Although that wasn't the magazine I was referring to, I will check it out.

[Murphy]

Don't know how much of a motorhead you are so if you already know this just ignore it. The quickest way to pick up 2-3 miles per hour is to make sure your engines are timed perfectly. I don't have specs on a BBC, but on my SBC with Thunderbolt IV, the target is 32 degrees btdc at WOT. While the recommended advance is 8 degrees at idle, I have to time at about 9.5 degrees btdc to get there. If you can't do it yourself, find a mechanic who will slap some timing tape on your balancer and check the timing at WOT with the boat in the water in neutral. Even a variance of just 2-3 degrees can cost you rpm's and 2,3 or more mph.

Murph

[MOP]

You can purchase spring and weight kits for most any distributor. You need to get some ideas from the big block guys on what advance curve and total timing for you setup. There are some very knowledgable guys up here that have Been There Done That.

[MOP]

Murph! I know you did not mean WOT no load, want the boy to poof his machinery? Just bring it up slow till the timing peaks thats all your going to get and well below top in gear RPM.

[mattyboy]

I got schooled @ Lk George
your gonna need 50+ hp to gain 1mph in your speed range

which I could post the paper work that was given at Dustoff but I ain't got no scanner :o

can some one assist me here ? Poodle? any one

1mph = $
2mph + $$
and so on

Matt

[mattyboy]

Scott,

I think that covers it!

Matt

[JP BRESCIA]

Yes, I is in the July issue of Family and Performance Boating pg 28.

[Murphy]

Poodle and M.O.P.'s comments above are well taken. I was a bit brief. In the water or on earmuffs, either ways if fine. I like doing it in the water (oh yah) because then I can immediately test the results. If I get better performance underway I know I'm going in the right direction. Also, you just run up the RPM's in neutral until the advance levels off, not until a rod pops you in the eye or the manifold starts to glow. My thinking in offering this is that many engines are UNDER-PERFORMING due to poor timing. It's possible some are way off. If so, it may be the cheapest horsepower you ever got back. As with everything, don't try this at home unless you know what you're doing or have a bag of money in case you f/u.

Murph

[Murphy]

Poodle,

I'm more into speed, so that's what I base my testing on. Max rpm, max speed. On my modified sbc the magic number is 32 degrees on the nut just as spec'd. Properly trimmed, the tach is dead-on 5k at WOT. With more trim and a 20' rooster tail she'll turn 5200. When I advance even 2 degrees past 32degrees I lose top end rpm. Anything less than 32, I lose top end rpm. Overall I don't notice any change in low end. Even with an Alpha SS I don't push the hole shot thing too far though. Last night I dialed it in and was reading 62mph on the speedo at 5000 rpm with a 19 pitch cleaver. Not bad for a mouse in a 22 Classic. Time to try a 21 pitch.

Murph

[Rootsy]

if you want the best of both worlds get an MSD Digital 6... program in your own curve using the thunderbolt or any fixed (read non-mechanical advance) distributor... you can drop back a degree or two above say 4000 rpm (or whatever and whenever you want) that way you get the best acceleration and fuel milage at cruise but when you really want to get to the top end you can drop a degree or two and build a bit more hp at WOT... lot of the NHRA and IHRA sportsman racers are beginning to move to this over conventional CD Ignitions... helps pick you up on the top end since most run a straight fixed advance number using a crank trigger from idle all the way out...