Need more holeshot power

[lhkrueger]

This is an 83 S+S PS 351/240 Hp and the engine performs flawlessly. Beautiful restored old-school boat. Engine is out for winter. Customer wants to add power for multiple person deep water slalom starts. We are familiar with hot-rod engines ( power band 3000 to 7000 rpm) but not marine ( power band 500 to 4000 ). Looking for specific guidelines...comp. ratio, cam lift/duration, flat or roller, head selection, valve size, carburation etc. Cost is not an issue but we don't want experimentaion, rather proven performance. Need to know what actually works real world. Thank you all in advance for your help.

[east tx skier]

Modern CNC Prop, Heads, Intake, Cam from research cams. Should get at or above 300 hp with plenty of torque. Can go higher, but that always seemed like enough for me.

[wheelerd]

Assume you are running stock 13 x 13 prop? If so, re-propring may be the cheapest way to go for increased hole shot. You may lose a bit of top end, but with the new CNC'd cupped props, it's not as big a difference as in the old days. Unless you are footing the 40+ mph top end isn't that important anyway.

As for engine mods -- there are quite a few threads here on TT. Recommendations include:
- GT40p heads -- quite readily available on Ebay or elsewhere
- Edelbrock Performer manifold (or equivalent)
- cam - check out www.camresearchcorp.com/ -- they specialize in Fords (JEGS or Summit also have similarly configured cams)

I was planning to do this whole treatment to the engine in my TriStar and had purchased the heads and manifold, but ended up selling the boat before I ever did it. Cam specs I came up with after extensive research were:

int/exh
.450/.480 lift
260/275 duration
112 separation
1800-4800 power range

[thatsmrmastercraft]

Have a conversation with Eric at OJ Props. He has been around the block once or twice and will give you some great prop recommendations. 865-458-5205 http://www.ojprops.com/

I agree with east tx skier, getting in the area of 300-325 hp with the right prop will do exactly what you want.

[lhkrueger]

Thanks all. Is powerslot so has big prop 14/18 with gear reduction. Cam specs are great and 300-325 hp with gobs of low range torque is the prime objective. THANKS

[thatsmrmastercraft]

Please keep us in the loop on how this turns out.

[northof52]

.....if you we're only to recommend one of those upgrades.....which would it be? I have a'90 prostar...and have been tossing the idea of the head upgrade

[j.mccreight@hotmail.com]

Originally Posted by northof52

.....if you we're only to recommend one of those upgrades.....which would it be? I have a'90 prostar...and have been tossing the idea of the head upgrade

Cylinder heads alone are not worth doing.

I did all these engine mods (1989 TS190 351W 1:1) over the summer and from MY experience the best single mod for your money will be an acme cnc prop, you will gain hole shot and top end with just a prop change. While I gained about 400 rpm from the top end kit (aftermarket heads, roller rockers, intake manifold and camshaft) and had very good hole shot but was not any faster with the original OJ legend 13x13 4-blade. I was left feeling there was still more on the table, after the prop change, Acme #541 13x12 cnc 3-blade it had even more hole shot and was even faster (47mph@5000rpm)

[east tx skier]

Originally Posted by j.mccreight@hotmail.com

Cylinder heads alone are not worth doing.

I did all these engine mods (1989 TS190 351W 1:1) over the summer and from MY experience the best single mod for your money will be an acme cnc prop, you will gain hole shot and top end with just a prop change. While I gained about 400 rpm from the top end kit (aftermarket heads, roller rockers, intake manifold and camshaft) and had very good hole shot but was not any faster with the original OJ legend 13x13 4-blade. I was left feeling there was still more on the table, after the prop change, Acme #541 13x12 cnc 3-blade it had even more hole shot and was even faster (47mph@5000rpm)

Agree 100%. The intake and heads are a great combo upgrade after the prop. But since you already have gear reduction, you already have plenty of grunt out of the hole.

[thatsmrmastercraft]

Also agree that if one change is to be made it should be a new prop. I would also look at the ignition system and upgrade to electronic (if it isn't already) and confirm that you are getting all the advance you are supposed to. I would also go through the carb as well.