Underdrives and Engine Cooling

[Smokie]

Do underdrives decrease the circulating capacity of the water pump ? I understand we have some issues with the number 7 cylinder running hotter, would underdrives agravate this problem ?

[Smokie]

Hello, Anyone ?

[GarageMahal]

Hello, Anyone ?
Yep, I'm here, but I don't have the answer.

My guess is that it would not unless either the main crank or water pump pully is changed. I don't know what all comes in the kit.

jta

[Paul T. Casey]

Don't know for sure, but I would think that there would be less volume per unit of time. But when the thermostat is changed at the same time, it would be open more often, there-by increasing the volume per unit of time. With the careful observance of the temp. gague I've noticed that my engine temp, so far anyway is actually a touch cooler than before, so if I was you, I wouldn't worry too much about it, I don't. From my past discussion with TTA, he had his troubles with a completely stock setup.

[TAF]

Javier,

I don't know the specific answer to your question. But...I can assure you that I have confirmed with SEVERAL wrenches (with MUCH more knowledge than me) and by my own personal experiance with the "undies"...

There is NO downside, concern, problem, potential problem, ill-effect...PERIOD to adding "undies" to a Marauder.

[GarageMahal]

There is NO downside, concern, problem, potential problem, ill-effect...PERIOD to adding "undies" to a Marauder.
Unless you are running a lot of added electronics... like a gazillion watt stereo. :shot:

jta

[TAF]

Unless you are running a lot of added electronics... like a gazillion watt stereo. :shot:

jtaI don't even know if that^^^ is true...I've not seen or heard of anyone with "mega-upgraded" sound systems, G-tech, radar detectors, laser jammers, etc. chime-in on that.

[Smokie]

Thanks Paul, it's hot down here, a lot of bumper to bumper traffic, often. I think once operating temp. is reached the thermostat remains open and no longer plays a role in engine temp. until engine cools down again (if this is wrong, please advise) I find the underdrives very appealing and my concern is, here in Fla. would it make the cylinder 7 temp. issue a concern.:confused:

[Smokie]

Todd, when Dennis recommends an improved cooling kit I thought it meant that stock cooling was not ideal, and turning the water pump slower in bumper to bumper traffic might make matters worse. It is very hot down here almost year 'round. Thanks, Javier.

[Paul T. Casey]

Unless the temp. on the gague is climbing, I'm of the opinion that the coolant is working. If you're in traffic, you can watch your gague, if it goes up and down a little, the 'stat is still opening and closing.

[Smokie]

Unless you are running a lot of added electronics... like a gazillion watt stereo. :shot:

jta
Nope, just the stock unit.:D

[TAF]

Todd, when Dennis recommends an improved cooling kit I thought it meant that stock cooling was not ideal, and turning the water pump slower in bumper to bumper traffic might make matters worse. It is very hot down here almost year 'round. Thanks, Javier.Javier,

I'm sure I'll be corrected by someone with MUCH more knowledge than me if I'm wrong.....BUT...I think the REAL purpose of Dennis' "cooling mod" is to allow for a more aggressive knock sensor setting (or lack thereof, whichever) due to the accumulated effect of running more (and more effecient) cooling around the heads.

I don't think there is any relation to this mod and the ability of the underdrives to make sure waterpump pressure/effectiveness is optimized.

How 'bout some help from the more knowledgable here??

[FordNut]

Dennis' mod improves cooling to problem areas, which are the rear of the heads particularly the driver's side. This is where failures have been noted when very aggressive timing curves are used by performance tuners. So the limiting factor for tuners is actually these hot cylinders. With the improved cooling, these cylinders are no longer the limiting factor so more timing advance can be used. The knock sensors are supposed to prevent the problem, but some tuners disable them and even if they are not disabled the knock must occur before the sensor can dial back the timing. That may be too late, especially on a supercharged car.

But this has nothing to do with the underdrives. We have some Texas members who have run the undies in the summer all last year with no overheating issues.

[TAF]

See^^^ I knew Brian would know much more...so...I wasn't TOO far off, eh?

[sailsmen]

I have underdrives in South Louisiana with no cooling problems, lots of congested bumper to bumper, long times in park with a/c on, ect.

I beleive the head cooling issue is due to the way the heads were cast, the water jacket is too narrow near a hot spot to the point that the coolant can vaporize. Vapor compared to liquid has poor cooling characteristics. Vapor can also cause a pressure area reducing the flow of coolant.The elevated temp in this part of the head results in pre-ignition which can melt the associated piston.

Best to ask Dennis, but I believe the head cooling kit allows the coolant to back flow thru this area, increasing flow.

[Smokie]

Thanks for the input all !!! I am taking a very careful approach to add-ons. First and foremost trying to prevent dealer from declining a possible repair because of a non-oem part ( in july of '05 warranty ends )and also trying to get best bang for the buck on limited resources. My long term goal for the car is to build a " Grand Touring " machine a la Todd with some minor variations I prefer the stock gears and have a preference for the roots blower.:coolman: