im not hating but just because ilmor has been able to keep these things quite does not mean they did not happen they have lost several of the new 725 motors in europe and yes they were in a race boat but the problem did does exits

Back on topic, folks. This is about NASCAT's project, not run-on sentence rumor mongering.

Nascat:

Thank you, for your expansive explanation on gear ratio selection. I appreciate the process and not the conclusion and I do not care who is providing the end result data so long as they show me the work to back up the claim.

If you have so much data concerning the other three ILMOR cats than please share with us what the results were i.e... roll on acceleration numbers, time to plane, 80 to 100MPH times, and top speed etc...and explain how it differs from your intended goal. What are your motors putting out in terms of HP/ Torque any modifications done to the ECU, heads etc...

If this is somehow a promotional thread for the ILMOR people than say so rather than referring to post counts and views. If it is... I'm ok with it but the hard facts and the why is what I want to read about. If this is gonna be a cheerleading thread then let me know so I won't bother you with poignant questions to which you are unable to reply or feel slighted.

I appreciate your intended goal and read what you wrote. However, if the overall performance of the boat is far superior in an alternate gear ratio--- as a consumer reading a promotional thread it would be something I want to know. Usually, the truth never comes out the parties act much like what Boatless's describes i.e... swept under the proverbial rug in a hush hush manner.

I really think your statement about testing is a valid one and your right if this is a test bed for this gear ratio combination than go for it and let us know if it was the right choice.

Lastly, what did ILMOR recommend for gear ratio and power in this type of hull given that it is a retrofit project [if it matters at all].

FYI---In April I was considering whether to purchase this type of hull and power it with ILMOR motors 725's but not with INDY drives [I'll pass on being the guinea pig] my first choice would be a proven drive system such as Arneson drives. Then again that doesn't exactly fit the promotional plan now does it just messing with you don't get all uptight.

KAP

P.S. I wasn't aware that spec. SCL cnc cleaver props were rated to 700HP.
P.P.S. What is the rev limiter set for your motors?

That is False. The 2nd OL order (44) was meant to have 725's and Indy's but they optioned out of it and put bigger power in it.

The 1st boat has 650's and is pushing 200 hrs or has possibly surpassed that. This was our first set of production drives on this boat. We had a few issues at first and were very pro-active to resolve them. OL and the customer were patient and understanding during that time. The customer is in good relations with ILMOR and has given us great feedback. The boat runs 115 mph with 650's.

So, stick that in your pipe & smoke it.

NASCAT - For what it's worth, I suspect that you will eventually end up with 1.39's for the very reason that you identified - the paddle wheel effect of too severe a pitch angle. As a fellow racer, however, I fully appreciate and applaud your willingness to test. (We both know the ratio of positive test results to negative, don't we?)

I went the opposite direction, using a very low (28") pitch prop spinning at higher rpms because I was worried about the effect of prop torque on a single-engine pad bottom boat with a 5'9" chine-to-chine width.

I'm not sure that I understand why a high-ratio/high-pitch setup is supposed to accelerate better that a low-ratio/low-pitch setup. In the end, power comes down to torque x speed, and the input is the same. It's kind of like "why would a car with smaller diameter tires and a taller rear-end gear accelerate any differently from a car with large tires and a shorter ratio???"

Anyway - It looks like my "within 5 mph" prediction wasn't far off, was it?

And.....Yes - I am cheerleading for Ilmor.

What nobody has mentioned yet, is is how fast do you really want to go in an open cat?
Do you really need to be going 140++??
I've got a 32 skater with 710 Ilmors with #6's and 1.5 ratios with only 35 pitch merc props, and I'm topping out at around 120ish.
Funny thing is, at the last poker run we ran, we were the 3rd boat to the first card stop right behind Danny Desantis in his new 40 skater with 1550 sterlings (180 mph boat), and then Dr Bill with his 36 skater with big sterling power (175 mph boat). We got there ahead of some other boats that were supposedly alot faster.
I'm not so sure I want to be going 140+ in an open 30-32 skater, I'd rather stick with the 1.5 ratio to get more real world acceleration and overall performance.

Damn right we were Steve! A wicked accelerating 30 would be the way to go!

Holy Sh*t!!! Really??? It's NASCATS Boat, He Boats on a lake in NC, If he want's to Set his boat up for acceleration He Can. He doesn't have to set a Top speed for a 30' Skater. 1:50s open up a bigger array of props to try. He's working with a bunch of smart people.1) The Company who built the Boat 2) The Company that built the Motors and drives. Do you think there is More usefull Data than they can provide? You seem to. It's a thread about redoing his boat and how it goes throughout the build. Nothing More, It wasn't to convert merc owners to swap motors, it was about repowering HIS Boat,Jeez...

We have a winner!