How much HP needed to get 38' to 100 mph?
 

Thought I'd ask this question as I have no idea.

2003' 38' Top Gun with Bravos. How much hp is typically required to get the boat to 100 mph?

Customer has one with pro charged engines claiming ~900 hp and does right at 100 mph. Can this be right?

If it really has 900 hp then that would be right.......

My Formula 382 had 500 EFI's with 8 psi Prochargers when I bought it. They claimed 830hp, Precision Marine claimed to have dyno'ed several at around 790hp. The Formula is probably 6-8 mph slower than the TS Top Gun.....I saw 95mph, supposedly the boat ran 98 when it was first built. I bought it used and have since taken the Prochargers off the motors ... only ran it WOT once.

our 2006 38 Top Gun does 92mph with 600 mercs. 700s in a 39 does anywhere between 102-106mph. So 700 would be a good estimate. Don't count on those bravos holding together for very long with 700+hp running through them though.

How similar is the 39' to the 38' Top Gun?

700 and the right props and its should do it

CORRECTION: It's a 2003' 38' Top Gun, not a 2006'.

Here is why I ask.

They tell me:

Now we have the power of 850 horsepower. Top Gun 38 has the gear ratio 1.5:1 We use propellers Maximus have five blades. diameter of 15 1 / 4 X 32 inches with Sport Master lowers.

But last season we achieved record at ratio 1:1,26. on the propeller Hering 15 - 5 / 8 Which had six blades and step 30 inches. Then, our speed was 102 miles. Engines was 920 horsepower. But it was risky. BRAVO broken six times.

A power cut up to 820 horsepower for reliability. Speed boats with these conditions, equal to 92 miles per hour. Engines have a turnover in 5400

Then they Blew the engine, broke rod and a piston. Seems it should have been faster??

So, they wanted a change from Bravo's since they pulled the engines and had to rebuild them. They dyno'd at 734 they tell me.

I do not, nor do they as there are no markings on them, know the propeller pitch with the change. First time in the water the boat runs 100 mph now with the lower hp setting.

I think this seems more realistic but didn't know what it should be doing in the first place.

Wonder if it was a drive failure that made it barrel role??

It's a bit cold in Moscow this week, so no more sea trials this year. (they converted the boat in about one week) and only had the insanity to run it in winter once. The boat runs the same speed with lower hp than before so this is a positive note for the first sea trial.

?? That was before they had contacted me. They all went swimming they told me.

It's on video.

Doesnt seem right
 

That boat should be faster than that with that many beans in it, but Dynos are all different. At the same time the sportmaster lower "cost" my tunnel hull 4MPH compared to the original B1 lower.

An engine on a dyno pushing through car headers usually makes more power than it will in the boat with a marine exhaust- and Ive seen so many dyno cheats to sell a build it's ridiculous- not making any speculation about your guy just telling you what Ive seen.

(when I went to Edelbrock they actually had the room pressurized-! I had to lean my shoulder on the door to get in the room!)

Comparatively the LaveyCraft 39 Evo runs about 105 with 700's and NXT drives. Its probably a lighter boat but not enough to overcome a 2-400HP difference in power and you know it doesn't have a pony more in it or Mercury would name it - the 701

Sorry about your drive problems- that sux.

Video is crappy so switch to high quality and forward to about 20 seconds in.
http://www.youtube.com/watch?v=6NVpj09ejnk

Uncle Dave

LaveyCraft 2750 Ilmor 710
LaveyCraft 20.8 406 SB

I see what looks like a CMI elbow top in the dyno room shot- and when I look at the dyno chart I dont see a correction factor on the printout, and that can swing a number a long way - but it sure looks like the guy set up the dyno and ran the marine exhaust.

Uncle Dave

LaveyCraft 2750 Ilmor 710
LaveyCraft 20.8 406 SB

you must not deal with mercs too often, 525's make around 560-580, 850's are around 920 and 1075's are pushing 1125-1140.... i would estimate that a merc 700 makes that at the propshaft, easy. merc has a bad habit of under rating thier power levels, but none of that is really the issue here. :grinser010:

and i think Rik solved their drive problems. :drink:

the 39 is 8 inces longer to alow a staggered engine set up

Actually I do..
 

Actually Ive been buying and using mercury products all my life.

Accepted testing sources that Mercury themselves do not dispute do not back your claim- note the enclosed document.

A 525 makes about 470 propshaft horsepower and the newer blower engines are electronically "bled" or timing retarded- to keep them at that level of power at sea level or altitude -claimed ( for insurance purposes)

Take a look at a series of comprehensive tests by several major magazines and note how when a mercury engine is tested they indicate what boat has in the way of propshaft horsepower instead of whats stamped on the Engine. Custom engines are quoted dyno HP.

My latest purchase is my first new non merc setup Ive bought however- Ive switched to Ilmor and you can look at my 2750 in the Laveycraft forum.

Please post any real comprehensive 3rd party data you have backing up your claim- Id like to see it.

"Because you said so" carries no weight.

Uncle Dave

LaveyCraft 2750 Ilmor 710
LaveyCraft 20.8 406 SB

one of the best running 2003 model 38' Top Guns that I have been in was a 675hp KE motors, Stelling extension boxes, XR uppers and Imco -2" lowers, 1.50 gears and 102mph with 2 fat guys and 3/4 fuel.

I know. My point is that happened last year sometime so it happened before I was involved with them so I don't have the details of what caused it rather they sent me the video of when it well after it happened.

They are very very happy. They lowered the HP to make the engines live and they did not loose any speed.

They have kissed their drive problems good bye!

I suppose if you are going to reach those sort of speeds with this sort of set-up problems can occur. Reliability of the engines and Drive breakages being the norm I assume are minor in comparison to being ejected from the boat at low speed ! Just my 0.2c
The boat accident was this summer in July. and since then has been re-built with new arnesons and the same engine package......
Duna :rolleyes:

I posted the video of this boat some time ago rolling over on its side in an attempt to see, 1. is this common on Cig's 2. to see if anyone knows what causes and 3. to see if anyone knows a cure as I did not want to get involved with a problematic boat.

Of course, they had already committed to the Arnesons well before they sent me the video and they had no comments on the cause.

Any idea as to what caused the side roll?

In the video, the driver is out there running circle track laps with much smaller boats in his 38. When he gets pitched, he attempts a hard right hand turn at slower speed right before it catches.

Twin Steps Cigarettes don't react as quickly to hard turns because the drives "should be" somewhat trimmed out before making a turn. You have to let the boat take it's position into the turn naturally, rather than keep forcing it more and more to do so. At slow speeds this can be more pronounced especially if the drives are still in a higher speed position.

If you force it, it WILL eventually catch, but then the drives are turned too aggressively for a smooth transition. If they're turned TOO much, the hull will "catch" and yank itself into position which will likely throw everyone out depending on the speed. If that guy had been going faster, it would have likely rolled on over. If he'd punched the throttle when it started gripping, he might have saved it. That's tough to think of in the heat of the moment, and hindsight at best.

I've tested this by myself when I had my TS Gun, just so that I would know the boats likes and dislikes. They definitely aren't meant to run in such a small area like the one in that video.

Also, if it had Arneson's on it during the accident, I was told by Neill that the TS boats aren't as agile with surface drives due to the "dirty" water coming off the steps at the rear. I have no experience with that setup though.

With 900hp that boat should be running 110, assuming the drives would allow it to get there. I like the yellow. :cool:

BLee, the purple/pink 2004 38' with 900hp Sterlings and #6's ran 108mph all day with Mercury props!!!!! Greeklightning's old boat. One of my all time favorites also???

Yeah, that was a fast boat. I wonder if anyone ever got it dialed in better? The #6 drives sure make a big difference.

I don't think so, it should run 110 to 112mph dialed in and with Herings? A 38' with #6's is sweet.

Hey Rik. Great job with the Arneson package.:cool:

My only remark was with the previous set-up, and trying to attain speeds at or over 100hph. Power steering a must. Pro-charged 575s knocking out 850Hp, Not a reliable package.
The guys who work on the boat are a great team and committed to doing the best they can to get results,
I am sure they have gone through many drives and pro-Charger set ups .

Good job the mishap was on a Lake/River. with people present !! and not out in the big water offshore.
Duna :eek:

Thanks, it had Bravo's on it during its little fun ride. I was just worried after seeing that video.

I think they have had their share of engine problems to go along with their Bravo problems.

Why did they never go faster with all that power they had? I know they had engines and drive issues but I would have though it would have coasted past 100 with that power before either broke.

How do you know the Yellow Boat?

So, 900's = 108

675 Eickerts = 102

and this boat 920 hp with Bravo's = 100 and now 730's & Arneson's = 100

Are all the bottoms the same? I wonder if they all have the same basic interior below?

Interiors of the TS models, for weight discussion purposes, are all essentially 2 styles, either an extended cabin with the front v-berth, and couches on each side, OR just the couches, with the front v, unfinished. While the first style would definitely add some weight in the front I don't think it would carve MUCH speed off.

The purple one Blume mentioned has #6 drives, and wasn't balanced well at all, which made it porpose like crazy. It isn't a great example to use as a reference. "Hot for Teacher" is the best running 900/#6 TS out there for comparison.


There's a 38TS in California with Zul 750's, XR's, and the extended covergirl cabin that ran 105mph for Powerboat Magazine. Probably 100 most of the time?

A friend of mine has one with Sterling 750's, XR's, same cabin, that runs 100.

The bottoms on these boats are the same, and the difference in the "half cabin" and extended covergirl is minimal.

My guess is that the motors the yellow boat has never made 900hp in the first place? That, or they need to try spacers and different wheels. 750hp a side with a dialed in set of wheels on the correct drive height should get 100+ everytime.

and Tom's boat "Hot For Teachers" has wet sump 6's w/dry sump keggs and runs that good???

Thanks!

Yeah, I wasn't meaning top speed as much as overall handling at top speed.

It's in a few of those SCOPE videos and runs with a great attitude and flys perfect at speed. I don't know what they did different in the setup from the other two #6 TS guns, but it's the right one.

If he dry sumped it he might gain a little, but I doubt it'd be enough to be worth it on that type of boat.

I'm still amazed it took so long to sell that boat when it was new! :eek:

What is the fastest 38' TS? I am guessing it would be a stagger setup..

I don't think there are any TSTG's that are staggered, only strait hulls and the 39's are the staggered hulls.

I believe Greek Lightning told me the big power 38 was so scary no one would run it to the limit. He said sea trial day Neill would not go out on it...

Gotta be this one. 1150's/6's

All of the TS 38's are side by side like Bongo mentioned.

Sorry, this is the only pic I could find. :readinghelp:


http://img134.imageshack.us/img134/1394/fastgunwa7.jpg

here's some more!!!!!!!!!!!!!!!!!

2002 38 side by side 725 cobras, xr's on stellings boxs and the boat runs 104 mph at 5700 rpm also in fresh water. when they first did the sea trial in fl with phil and randy they had the boat running 107 mph, the fastest bravo boat ever at the time.... with 900's the boat should run in the 1teens. most likely never had 900 hp, more like 700-750. the arnesons look nice.