Linster

Ovals on a big CU just dont add up in the old school, but I have been wrong before and have no knowlegede of these heads yet. I still think these numbers dont mean anything, 6500 RPM will blow up a bravo in short order. Also I do agree if you spin this up to 6500 RPm you will get his kind of number but you do not have any more usable torque out of the motor to spin the RPM high. HP works great in a car where it coasts, but the faster a boat runs the more drag it has, Torque is the key and most engine run out of torque at 4500 so at about 5500 you have achieved top speed on pump gas. We are not talking blower motors here. I do not know nothing of this builder & by NO means am I trying to slam him, He may be right on target but it does not work for what my garage engine stuff shows. Please keep in mind I like talking this and by NO means claim to be an expert.

Just my 2 cents

AIR TIME

My motor makes 637tq at 4800 and 600hp at 5050 and peaks at 6000 at 670hp now. when I was out testing it was still picking up speed at 6000, but ran out of room last fall. I plan on propping it at 5700. for speed and lower if racing with a limiter. its a 509. guys I now with blowers seem to have more troubles, than the guys with the 572s and 598s. like I said my old builder said for 16,000gs he will build 598s 802hp or 820hp I for get. that was at 6000, and the tq was peak at 4800 or 5000, both motors 114 cams, hdy roller. my motor has low hours since I have been injuried for the last 3yrs but 8 or 10 hours on it

jdnca1

The new Dart Ovals have 370CC runners.. and will absoluty Destroy a full CNC 355 head. They have not been out for that long, think of them as a "tweener" of std 24 degree stuff and 14 degree chiefs... Of course you have to have a sheet metal intake manifold made to fit them..but I'm told they (18 degree) will make another 75hp over the 355ish stuff. Remember big inch motors tend to really calm down very large cams. If you go solid and stay in the 264/270 @.050 on a 114 and around .700" net lift "range" with a soft lobe, they will make great power to 6500 and live, make over 800 ft/# of Tq and idle pretty dam well (800rpm in neutral, 600 in gear). We regularly turn bravos 6500 without any issues..sure the pinion gears eventually break from beating on the rev limiters, but many have lasted 100-200+hrs. Most of the guys I run with have cats...and cats love rpm...just look at what the Merc supercat NA motors turn...~7500rpm and they also make peak Tq down relativly low...I understand the Tq/HP relationship and argument, but depending on the hull...prop speed also comes into play in a big way

Panther

I agree 100%

I've seen bravo boats with power 700+ live much happier spinning 6000-6500 rpms range then those who spin in the 5000-5500 ranges. The bravo's can't handle the torque so RPM is the answer.

Speaking of high rpm supercat syle of motors! http://media.putfile.com/OTC-Patchogue

jdnca1

Here is a "profile" of the 370 Ovals from someone that knows a little something, something about heads...

http://www.sonnysracingengines.com/p...portheads.html

tomcat

A plug for superchargers...

A 540 with good heads and mild hydraulic roller will make a conservative 600 HP. Adding 50% with a blower is also a conservative figure. Yes, it will break your Bravo drive, so go with the Konrad ACE.

The Konrad package uses our supercharger system with pullies and EFI program for 800 HP @ 5200 RPM. We sell this system separately and one of our customers has already changed to smaller blower pullies for 900 HP. Idles like a 500EFI.

bobl

More food for thought...Generally A smaller engine with a supercharger will get much better economy at cruise than an equal horsepower NA engine.

jdnca1

How much are the Konrads able to hold...real world? I know what the warrenty says, but how much have you seen put to them with relatively few problems? Might be something to consider for the next boat down the road.

mrhorsepower1

Need help. Call Me. NO BLOW!

Best Regards,

Dean Gellner
Gellner Engineering Marine Power
(216) 398-8500

Biggus

I've got 340 trouble free hrs, installed spring 04, on my Konrad drives behind 700hp blower motors. At this power level they are unbreakable.
The Konrad 540 was originally designed for a diesel making @800 ft lbs tq at 3000 rpm.

We warranty the drive to 800 hp. We are very comfortable at 800 hp. We do have many customers running 900+ with no problems but we make it clear that is not our market.
The Konrads work very well when installed for what they were designed for.

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