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NXT Drive Problems ?

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Old 02-23-2007, 05:48 PM
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Originally Posted by Bottomfeeder View Post
I had a 07 38 Fountain with t-525's last summer and the port engine oil filter came loose @ around 5000rpm there was aprox 3 oz of oil left in that motor when I drained it and had it sent out for analylization, Merc says " run it and see what happens" this is 1 week before I go on vacation to Tahoe for 4 weeks .HOW WOULD YOU FEEL after spending 250k cash on a boat and 20k for my rental ?
I had that happen once - Merc warranty registered it in case something developed later from it. The computer saved the engine, no issues at all. I agree Merc's response is weak, and they abviously went through a period with QC issues in putting oil filters on. Seems pretty basic!

On the other hand - it would probably have roasted any other engine.
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Old 02-23-2007, 06:04 PM
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Just dealing with theories. The reason for the big power loss on bad air days is due to the 3.960 stroke and 9.6:1 cr ratio and no way to change that no matter what the barometric psi of the day is. I know the 710 ILmor is a 10:1 motor in which is one of the reasons for a higher rpm. What mercury racing has is a boost bypass control system. In which it can vary the boost psi on the MAP reading. Basically make better air for you on a bad air day (115-120 degree weather, altitude.) You have to look at where the peak hp numbers are. 5800rpm vs mercs 5300 on their 600sci. Spinning a motor past its peak hp number is usually not gaining any results other than telling you that you need more prop. This is why peak hp numbers are critical. However, you have to have enough torque to get you their. In which can vary on the amount needed from a cat vs a V-hull. What is the point of a 6000rpm potential if the boat is to heavy to get you their because the motor does not make enough torque or you have to put a prop on that is so small that it does not even make sense.
What I have noticed is the Ilmors show their true colors in the cats. Reason is cats propel off of peak hp numbers.
The 700sciNXT or #VI package is a well developed package. I saw some early transmission probelms. In which Mercury Racing has taken care of. Just like anything keep on top of service and having an individual who knows the product maintain it. The Penske Ilmors have been good motors also. Food for thought. The 710 Ilmors have gone to stronger internals, why would they do that are they thinking about going blown for bigger hp #'s. However, complete packages are important in this business.
Thanks, Cam-shaft. Hopefully you were able to read all of it.
I agree accept about the Illmors going to a blown/turbo application in a marine, high constant load application. How many alluminun block/4 stroke blown marine engines are out there for consumer use? The architecture on the Viper/Illmor marine block will not support the boost and heat from turbo/blower packages in a marine envirement that basicly a dyno run, its not the same game as a Hennesy Viper thats in the throttle for 10 seconds,,, IMHO
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Old 02-23-2007, 06:07 PM
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I had that happen once - Merc warranty registered it in case something developed later from it. The computer saved the engine, no issues at all. I agree Merc's response is weak, and they abviously went through a period with QC issues in putting oil filters on. Seems pretty basic!

On the other hand - it would probably have roasted any other engine.
Exactly what happened to me! WHAT A MESS the filter being located by the belt and all
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Old 02-23-2007, 06:43 PM
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are you hitting the rev-limiters? who's got props? Dave ,,,I dont know?
Oh ya. Hitting them even with the 39s. Dave should be able to get ahold of some props to test.
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Old 02-23-2007, 08:16 PM
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Originally Posted by Bottomfeeder View Post
I agree accept about the Illmors going to a blown/turbo application in a marine, high constant load application. How many alluminun block/4 stroke blown marine engines are out there for consumer use? The architecture on the Viper/Illmor marine block will not support the boost and heat from turbo/blower packages in a marine envirement that basicly a dyno run, its not the same game as a Hennesy Viper thats in the throttle for 10 seconds,,, IMHO
Nothing said about a turbo. Maybe a centrifical. Internals is all I was speaking about. However, aluminum does work. Dis-reguard the name on the valve covers and look at the Donovan block.
Thanks, Cam-shaft.
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Old 02-23-2007, 09:01 PM
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Originally Posted by Cam-shaft View Post
Nothing said about a turbo. Maybe a centrifical. Internals is all I was speaking about. However, aluminum does work. Dis-reguard the name on the valve covers and look at the Donovan block.
Thanks, Cam-shaft.
Not exactly a consumer motor, butl like it There are quite a few guys using those blocks in dune buggys @ Glamis, 1000hp in a 2500lb buggy is not uncommin
I know what Merc puts in there Blue motors for parts, does anybody know what Illmor uses ? Are they just marinized,cammed Viper motors or are they ground up custom builds?
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Old 02-24-2007, 04:24 AM
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The Government has been using Donovan blocks since the early 90's. They did use closed cooling.
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