More Speed for 91 Supra Cobrio

[Paul 22]

Need a little more top end, any ideas?

[jasun]

Prop Pitch.

[michael hunter]

Call the prop manufactures and give them your boats specs and they will select the right prop for you.

[haugy]

What's your current top end? You may be getting all you can get currently. Set up right that boat at it's best should be able to do between 45-48mph.

[crystal waters]

have an 89 conbrio with all stock power etc. plus 1:23 to 1 transmission.
tuned to the optimum! max speed is 48 though I very seldom thrash it that hard!

[Paul 22]

I am only getting 38..................

[Paul 22]

38, the boat definitely feel like it has the power to be going faster. First weekend out in the boat to actually use it all around for barefooting, tubing and skiiing.

[Jetlink]

Mine did 40-41 max until I put new prop on last season. I can hit 45 now. I spoke to Nettles before buying a used one I found on here.

My Comp will do 45 without really breaking a sweat on the water, but for me to push it that hard it better be smooth as glass. The fastest I have ever had the boat though was 75 on the highway...:lol:

[NorCalPR]

What's your current prop? It would be printed on the hub.

Mine is a 4 blade 14X14, with a 350 Indmar on my comp I can hit 48 with people in the boat if it's smooth, and the wake plate is down.

I also surf and wakeboard and the prop does a good job.

[haugy]

Even with a bad prop, you should be able to hit 40+ pretty easily. What's your speed measurement? Your speedos can easily be off, and most of the time are.

If your speedo is by GPS and you are only getting 38mph, you either have a really bad prop or problem. If it's the stock prop, and it's not dented or banged I'd say engine.
You may not be getting enough fuel. Air intake/flame arrestor could be clogged or dirty. ETC

[Salty87]

what are the rpms at wot?

[crystal waters]

I am running an acme 422 four blade prop. Love it.

[Paul 22]

My prop size is 13 X 14, 3 blade.........

[Paul 22]

Prop size is 13 X 14, it has a 3 blade prop.

[cadunkle]

What is your current WOT RPM and MPH on GPS? We need this info to determine if a prop change may get what you want, if engine work will be required to make more power for more RPM or a bigger prop, or if your engine is not currently putting out the power it should be and needs to be tuned or repaired.

[Paul 22]

Will re post in a week or so, no time to run and get these answers. I have had several boats in the past, it seems to run strong and smooth, I have mostly been a jet boater so not real knowlegable on props. I footed just fine, another person with us had a weight of 210 and I needed more top end speed to keep him in a better position. I weigh 185 and had no problem on the boom or tumbling up. I will repost when all the info needed. Thank you

[Hagman]

The hull was not designed for speed. At about 40 the bow drops into the water some hull did more so than others. To compensate raze the wake plate and add some pounds to the back of the boat. A couple of blonds & full tank of fuel should do it.

[villain]

Just put twin turbos and a big blue bottle of NOS in it. Lol

[Paul 22]

I am between 2800 - 3000 RPM at full speed, seems like it should get more out of the motor.

[cadunkle]

Go over the basics, sounds like you're down on power.

Fuel filters replaced recently?
Throttle linkage opening throttle fully? Secondaries on carb opening (check for free movement of secondary throttle shaft and that diaphragm is not ruptured or torn)?
Point (if applicable) clean and correctly gapped?
Timing correct (6*-10* initial and 30*-36* total by 3000 RPM)?
Spark plugs in good condition?
Compression good in all cylinders
etc...

[92SupraComp]

how long since carb was rebuilt?

[Paul 22]

Thank you and I will be going through the items and suggestions this week.

[Hagman]

You should be getting about 4400 rpm. I think I would check to see if the distributor is advancing properly. It’s easy to check with a timing light. If it’s working properly it should advance about 20 degrees more form base timing by 1500 to 2000 rpm. CSI was having the same problem the thread was Hole Shot Power

[Paul 22]

Thank you and I will be checking this week on all the suggestions. I agree with you the rpm's are low.