Top Down Cooling?

[inline6]

Hi,

I remember reading about the 1996 corvette LT1 motor getting some innovative improvements. One of which was reverse cooling. Instead of running the coolant into the engine block and then the heads and out, GM reversed flow and the coolant came to the heads first then the block. The main benefit was that it allowed them to bump compression to 10.4 to 1 for more power. Here is a link to some of the info:

http://corvetteactioncenter.com/specs/1996/96technology.html

Anyway, I am about to take an E-88 head that I had rebuilt (L-28 intake valves, hardened seats) back when I first fixed up my 240Z, and put it on a low miles F54 L-28 block with flat top pistons. I am going to cc the chambers on the head and rerun the calculation, but with the figures I have now, I show 10.1 to 1 Compression Ratio. Might be ok with 93 octane, but might not.

An engineering friend of mine wants to take a look at what is involved in adding a belt tensioner bearing and converting the L series V belt to a ribbed belt like on more modern motors. I am thinking we can just wind the belt to reverse the flow of the water pump. Could just be a pipe dream as more would be involved like changing the propeller on the stock pump. Anyway, the idea intrigues me and we'll take a look and see if it is worth doing. Kind of trick if we can do it...

Garrett

[zeiss150]

great Idea, sounds like an expensive water pump. looks like a trip to the CNC machine is in your future. If you can figure how to reverse the flow direction let us know. bitch'n

MattROFL

[hls30.com]

I am up for the challenge! I have a turbo project that might benefit from the reversed flow. If I can help, let me know. I have "like this major set of tools." (includes a CNC Mill/Drill/Lathe!)

Will

[Mr Camouflage]

You could just make a mirrored impeller for the water pump, which would make the water pump suck instead of pump, with the same belts.

But you woul also have to swap the radiator pipes around, so that you werent trying to suck hot water from the top of the radiator throught the head->block->pump->bottom hose of radiator.

You'd want to suck cooler water from the bottom of the radiator through the head. Also if you had a coolant leak you wouldnt be sucking anything from the top of the radiator.

[ChrisA]

What about taking the CSI electric water pump and reversing the direction of the motor. Still have to reverse the impeller though. Might be better than changing belts and adding idlers and such. Here is a link to that page:

http://www.csiperformance.com/water_pump3.html

[Dan Baldwin]

My advice: spend money and effort elsewhere and you will get FAR more power for FAR less money, FAR sooner.

Consider that GM has WAY more qualified personnel, prototyping capability, measuring equipment, etc. than you do. Better to maximize CR with what you've got, IMO.

[2ManyZs]

Not only that, but the GM engine has a water jacket that is designed to be reverse flow. If you do this to just any engine, it's liable to end up restricting flow due to the shape and routing of the water jacket. Just because the coolant flows in one direction won't mean it will flow as well in the opposite direction.

To do this would more than likely require a head that is designed to flow in the reverse, and we all know what an aluminum head does when it gets hot. If you reversed flow, and ended up with even one hot spot due to the coolant flow being interrupted or having an air pocket, you will ruin the head in short order.

To be honest, I would work on maximizing the stock system.

[hls30.com]

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[hls30.com]

1) A generic style in-line water pump will make the conversion dooable in one afternoon. ChrisA had the right idea with the wrong pump!

2) I agree with Mr. Camoflage-reverse the inlet and outlet as well.

3) I agree that GM could engineer and prototype circles around us, but, If their engineers did the job we wanted them too, there would be absolutely no need for any aftermarket upgrades in any GM vehicle! I don't think GM accountants will let them do the job they are capable of!

Do you hand wash your Z, or do you take it to a automated carwash? Answer the question why, and you will see that you are aware that the tradeoffs forced into a product to make it cost effective are not always the tradeoffs we want our cars to live with!

4) Reverse flow will not and does not add any power, it moves the coolest spot of the engine from the bottom of the skirt to the head, hopefully lowering the propensity for detonation with the temperature, allowing the boost pressure/compression ratio to be increased, thereby increasing power!

5)This would be done after the rest of the easier and more cost effective things had been worked in.

6) Keep going with the alternative views-thinking is cheeper than prototyping!

Will

[zeiss150]

I think this could be a great Idea, with all of the brain power on this site Im sure this can be maid a reality. If you did reverse the flow I'm sure that it would be really easy to check that the coolant flowed at the same rate. It would be bitch'n to run 10.5:1 on 92 oct. If it didn't bennifit the engine the I dont think the GM engineers would have spent the time on top down cooling if they couldnt get more horse power out of it. You can't win big if you dont bet big. And if it doesn't work, SO WHAT! And if it does work...

My 4 cents

Matt-

[Dan Baldwin]

Go ahead if you must. I just hate to see a lot of effort, time, and money spent for next to no gain, and perhaps for a big loss! A Z on the road or the track beats the hell out of a Z in the garage or under a tarp, made into a cooling system science project.

In any case, if such a project is to be undertaken, the first order of business is optimization of the engine with the stock cooling configuration. Then, a LOT of dyno testing, varying the CR, maintaining consistent valve timing (cam tower shims), ensuring consistent A/F ratio, yadda yadda yadda, to establish a max performance baseline for the stock coolant flow direction. Only then should the reverse-flow system be implemented, and dyno testing repeated for varying CR.

FWIW, I'm running 11:1 CR on pump gas.

[hls30.com]

Dan,

I appreciate your thoughts on what may become a "cooling system Science Project"!

I agree, for the results to be meaningful as a whole, there has to be an appropriate basis for comparison, and changes have to be made one at a time, tuned for, and verified. There are a great number of tests that can be made before Dyno time and/or tuning would be necessary.

In the preliminary stage, I think this can be setup and tested for about $325 without damage or risk to the car if carefully, and thoughtfully done. It will only be proven to work in reversing the flow, and not overheating, but that would be a first step. If it doesn't work we have lost no more than one day and some supplies-sort of like a day racing when you don't win, but you do finish...

My project will be using a hacked GM ecm and its associated goodies to bring everyhting else into a consistant and data trackable performance. I will tune the engine in factory configuration first. I don't think the "Bo and Luke Duke" school of modification is an appropriate avenue to work from, but I also don't believe that it is always necessary to have an engineering degree to use logic and the scientific method to apply technology.

Will