MPH per HP (Average)

[bigblockbill]

I know I have read it somewhere but I can not find it now. Approx how many hp does it take to gain 1 mph in the low/mid 70 range on a shallow v-boat (jet) that rides nice and dry?

[moneysucker]

I know I have read it somewhere but I can not find it now. Approx how many hp does it take to gain 1 mph in the low/mid 70 range on a shallow v-boat (jet) that rides nice and dry? believe the equation is $1000 per MPH over 75 and $10,000 per mph over 100. Hope it helps.
Cy

[460 jus getn it]

Im running at 74 and some change and my motor is about 420-440 hp. Its not all about the hp, its how you set it up too....................................

[bigblockbill]

I know all about the set up part as well and we will address that. I was just trying to make an estimate on what we might be able to see with 150-200 addional hp (50-100 in motor mods and 100 in juice). Leaving everything else alone what type of mph gains we might see.
However to muck things up a ride plate, stuffer, and bottom work may be in the equation this winter as well.

[wright27]

We all know hauls are not created equal. That plays a big part. I had a southwind running 72 mph with about 420 hp put the same motor in my 78 challenger and ran 68 mph. Similar v bottoms but the challenger weighs more than the southwind. I put a 150 hp shot of nitrous on the challenger and saw 74 mph.

[QuickJet]

The Bahner in the pick ran 82.7 mph with nothing more than a stock Suburban shortblock, a cam that no one would reccomend, an intake ment for bling purposes only and a stock set of square ports. Couldn't of made more than 400 hp (if that).
http://www.hotboatpics.com/pics/data/500/10278IMG_0337MA14195371-0005-med.JPG

[ironman44bear]

Im running at 74 and some change and my motor is about 420-440 hp. Its not all about the hp, its how you set it up too....................................
I second that :crossx:

[jbone]

If you can find the JPC calculator (excell program)or get someone that has it to run the numbers for you that will tell you what gains can be expected per hp gained.
You need good starting numbers to get accurate results.
You'll need Current RPM, Impellor type, and Speed (GPS). This will tell you what your hp is now.
Then just plug in bigger hp numbers to see the change in RPM and speed.
And the 1k per mph seems pretty accurate assuming your setup is already dialed in.
J

[lil man wayne]

Like 7500 rpm and 50 mph.
Its a jet so dont expect alot :cry:

[TIMINATOR]

Shallow "V" needs about 20 HP/MPH gain at 60+ mph, depending on pump and bottom setups. We recomend putting a Cheater NOS kit on first. Borrow it.Try the various jet/HP setups and decide what you want. Don't forget the radar gun or gps.

[gunslinger]

On my last 19' CP a 200 hp shot of juice with no other changes picked up 8 or 9 mph. The hardware was already dialed in and the bottom was straightened. This was on GPS.

[bigblockbill]

Thanks for everyones inputs.
This JPC calculator sound interesting...does anyone have a link to it???
A buddy wants to pick up 7 mph or so so he can run the 70-80 mph class so I am trying to figure out what all we will need to do to get there.
The motor is just a basic flat top piston motor that will be getting a different cam shaft (hopefully I can convince him he needs a roller), intake, carb, and then what ever juice is needed to actually get to 80. The motor was dynoed in CA right at 500 hp but we are at 4200 ft and end up loosing about 100 or so for the thin air.
How much juice can hypertutecic (SP?) pistons handle???
The boat is a challenger 18ft with a stage II blue print job. Don't know anything about the bottom yet. I think it has a A impeller but don't remember right now.

[Squirtcha?]

Changing nothing else, a 100 shot on my Kachina 18.5 semi-V was good for 6-7 mph. The motor is a BBF with about 500 hp (off the bottle).
You could probably get away with a 100 shot and the hypereutectics.
The questions is.......................for how long?

[QuickJet]

Changing nothing else, a 100 shot on my Kachina 18.5 semi-V was good for 6-7 mph. The motor is a BBF with about 500 hp (off the bottle).
You could probably get away with a 100 shot and the hypereutectics.
The questions is.......................for how long?
At what point and time durring the run do you hit the bottle?

[HTRDLNCN]

with nitrous and hyper pistons timing,fuel delivery and fuel quality are everything.
right timing and fuel and you can run a 150shot or more,
bad timing,fuel curve or fuel and a 50 shot could damage one.

[Squirtcha?]

At what point and time durring the run do you hit the bottle?
I have a little slip out of the hole. I'll have the system activated, but it's on a WOT switch. Soft pedal it to 5000 rpm with the diverter full down. As soon as it's on plane I'll trim it to the sweet spot and hammer it. Naturally as soon as you hammer it, the WOT switch hits the juice.
I reckon the short answer would be "As soon as it's solidly on plane and trimmed for max speed".