Hi

After reading several different articles in magazines and
at the internet. I have following question: How come that
the Formula 353 Fastech with twin 500 efis has top speed
of 74,4 mph. The Fountain 35 lightning with twin 525 efis do
101 mph. The Donzi 38ZR with twin 525 efis do 91 mph.???
The Formula and Fountain has aprox the same weight 8600
The Donzi weight is 9500. Why this enormous speed difference?? I know that the Formula has alltoghter 50 hp
less than the two other boats.

Any comments?

for one it's more than 50hp a side difference
more like near 70HP (x2 130-140 hp total)

for another it's aerodynamics (the f & d are lower cut boats)

another is bottom. Interestingly enough it would seem the ride quality at reasonable speeds is inversely proportionate to the top speed capability of the 3 boats mentioned. This is what I understand from both reading, understanding a little about the geometry of bottom design, and owning a 353...plush ride at any speed.
This is nothing new in bottoms.

the speeds you quote are also about the highest achieved by the other two...ever (propaganda speed)

while that 353 speed quoted is 3-5 mph slower than routinely achieved in the real world examples of this package and there are alot more of them out there to back this up.

Isn't the 100 mph lightning staggered? My buddies '06 only does about 90.....

Hi The test result for Formula is from Boattest.com
Donzi and Fountain tests, from Powerboatmagazin.
In the sesific.it says 25 hp difference on each engine.

I need to say overall I am a Formula fan, I am in the process
to buy a 242 ss 1989 *S*

The seight you listed for the Donzi is probably not the ZR....the new Donzi and Fountain are staggered with more agressive steps than the Formula. Those 2 items account for alot of speed difference. (and I believe the Formula with 525's is an 80 mph boat...anyone confirm???)

The Fountain 35 Executioner, single step bottom, weighs in at 8500 lbs, with 500 EFIs it will run right around 80 mph, add the 525's and you should see another 4 -5 mph.

The Fountain 35 Lightning, twin step bottom, weighs in at 9500 lbs and most will run at 90 - 92 mph with the 525's in a side by side set up.

The newer, '07 and '08, Fountain 35 Lightning / ICBM weighs the same 9500 lbs, but is now built as a staggered engine set up. With 525's this one runs 100 mph, some have run more depending on the set up. This hull will run 90 +/- with 496 Mag HO's.

The Fountain 38 Lightning, closer to the size of the Donzi, weighs 9800 lbs and runs right around 90 mph with the 525's.

In terms of horsepower, the 500's are esentially 500 hp. The claim on the 525's, by some, is that most dyno out in the 530 - 540 hp range, supposedly Merc High Performance dyno's all of the 525's when built.

In terms of the Formula, not sure of the exact weight but think it's around 9500, and most with the 500 EFI's seem to run in the 77 -78 mph range. I would assume the 353 with 525's would be in the 82 -83 mph range.

Hi
The test on the Donzi 38ZR Powerboatmagazin May 06
9500 pounds 525 efi top speed gps 90,6 mp
Fountain 35 Lightning ICBM Powerboatmagazin May 07
8600 pounds 525 efi top speed gps 100,1 mp
Formula 353 fastech Boattest.com
8500 pounds 500 efi top speed 74,4 (add 1200 pounds fuel)
I understand that i was wrong when it came to the power
of the 500 efi I belived that it was 500 but I understand it is
475. If so we are talking at 100 hp in disfavuer of the Formula
explains some of it, but still a hugh difference *S*

quote:

In terms of horsepower, the 500's are esentially 500 hp. The claim on the 525's, by some, is that most dyno out in the 530 - 540 hp range, supposedly Merc High Performance dyno's all of the 525's when built.


i am very close to merc racing and can verify that all 525's prduced are in fact dynoed and produce 540-545 hp.

Hi Juked then we got that clear thanks

So, just for clarification:

525EFI is really:
540-545 crankshaft HP
490-ish propshaft HP

500EFI is really:
512-ish crankshaft HP
470 propshaft HP