38 Top Gun 1990
 

Hello all,
I am new here, I have bought a 38 Top Gun 1990, with a pair of 525SC and konrad drives.

I am redoing all the structures becauses the boat was in england and in france before, and now here in the caribean, and the different seas was very rough, so it needed some work....I will post the pics soon.

I have a few questions for you all if you can help me?

Today max speed is 70 mph with hydromotive P5X 25p

What will be the mph gain if I change the pulley of the compressor (now is a 3.5 and i want to buy the 3.05")

And for next project what power/prop if I want to go to 85mph with her?

Franck.

Welcome - what RPM are you seeing the 70mph at?

Can't help you on the blower question.

You'll need big power to go 85 in a flat bottomed Full Cabin Top Gun. I'd guess 800 to see it consistently, but that is just a guess. Some of the other guys who have actually done it can probably help you better....

Thank you,

I can see 5100 rpm at 70.

That's what i presume also, but I just want to know if someone done it before me (I guess yes.....)

And for the blower I am also very curious to know if someone done it also, and if there is no issues (less reliability or...?)

I'm running 750's and run low 80's at 5800 labbed 30's.

And its LOUD!!!

According to the Bam speed calculator you need 1500 hp to hit 85mph. I have a buddy with a 94. Topgun with 600sc's and it will run 81-82 but it is a Bravo boat and it won't do it every day. Also you should be looking for at least 5200 rpms. I would a run a 4 blade prop to either 24's or better yet labbed 26's.

I have a pair of 26 BRAVO, When i am in water, I will test it and see to send them for a lab finishig, but the P5X is great in big water!!! (but I can also feel that the 5 blades are hard to turn for my engines....)

thank you for the bam calculator, i went to the page, it's a great tool!!!

So in fact 800 hp engines will do it!!!, now I have to choose the engine......I like the potter 777, and it seems that there is no need to modify the hatch.....I have to work hard to buy them in 1 or 2 years.....

I'm just going to throw this out there, but instead of sinking 50k into a set of engines, you could just sell your boat, take the 50k, buy a Twin Step boat with a set of reliable Merc 575's and run 85 all day long without the liability of bigger engines behind you. Financially this would be MUCH smarter - dumping big money into a flatbottom is money you will realize pennies on the dollar for versus a T/S CIG where you could run it and maintain it for a few years and just lose a few thousand hopefully.....

realize pennies on the dollar for versus a T/S CIG where you could run it and maintain it for a few years and just lose a few thousand hopefully.....[/QUOTE]

You are FU KNEE GUY!

Just a FEW G's I wish!!

You are FU KNEE GUY!

Just a FEW G's I wish!![/QUOTE]

Im laughing my ass of right now Scott! you have that TS at Vincents yet?