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Reverse cooled vs. standard flow water pumps on LS1's

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Old 07-28-2003, 08:27 PM   #1
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Default Reverse cooled vs. standard flow water pumps on LS1's

I know the reverse pumps work well on LT1's, but with our engine design, will a reverse flow pump be that much better than a pump like the Meziere on our cars?

I have mixed feelings on this one and was wondering how everyone else feels.

I'm stuck between buying the Meziere and waiting for the JPR.
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Old 07-28-2003, 08:35 PM   #2
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

I would think that reverse cooling would be better on any motor. To have the heads cooled 1st is a good thing no? I'm no expert but I would think reverse cooling would be the way to go.
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Old 07-28-2003, 09:53 PM   #3
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

I tend to agree with StevieZ, although I'm not sure how much cooling the block needs due to it being aluminum. Does it need cooler water first?
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Old 07-29-2003, 11:13 AM   #4
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

They do it for emissions. Reverse cooling cools the heads off too much and allows for greater HC hangup and hence greater hydrocarbon emissions. The hotter the engine runs typically the less HC and CO emissions. Can't say the same for NOx though.
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Old 07-29-2003, 01:44 PM   #5
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

30thWS6 is the closest so far. You need heat in the heads to make the engine work right. Emissions performance and street performance (that would be the combination of fuel economy and performance) are very close. In rough numbers a ratio of 15 to 1 for emissions and 14.3 for economy. If the heads are always cold the engine is going to be looking for a 11.5 to 12.2 range to run correctly. This number is pretty close to the perfect full throttle acceleration ratio but. With the head at operating temperature. So when does reverse cool make sence? When the combustion temps will create other problems. The LT1 engine was reverse cooled to combat pre ignition the higher compression ratio was going to cause. When the computers got smarter they found they could bring up the head temps and keep the compression up. I can see no advantage to reverse cooling a car that has an average operating temperature above 165 degrees that is going to run for more than a few seconds. Another reason to not reverse cool the LS1 is: If you carefully look at the cooling passages, you will find a "built in" restriction as the water travels the normal direction. If you reverse this you will not be able to create much if any jacket pressure and on this engine that is more critical than any other GM engine ever produced so far. If you are running the "big bore" sleeves I believe reverse cooling would be harmful to the rear cylinders. Without good water jacket pressure and the cooling system circulating in the designed direction I feel the cooling system would ignore some of the hard to get to areas in the block. Sorry for the long winded post....but that is a very important matter.
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Old 07-29-2003, 02:23 PM   #6
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

excellent post J@work. Great info so far!
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Old 07-29-2003, 04:01 PM   #7
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

Hold on, are you saying a 14.3:1 ratio is ideal for fuel economy? A richer mixture better for fuel economy, is that a typo?
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Old 07-29-2003, 04:40 PM   #8
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

30thWS6 that is a leaner mixture. the smaller the first number the fatter the mixture.
also, if you could get around the restriction would this be a good idea for turbo cars?
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Old 07-29-2003, 04:51 PM   #9
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

What are you talking about? Am I just not thinking clearly? 14.3 parts of air to 1 part of fuel. Seems rich to me for optimum fuel economy. Same goes for every OEM.
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Old 07-29-2003, 11:11 PM   #10
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

14.3 parts air/ 1 part fuel

is leaner than....

12.2 parts air / 1 part fuel


the more air you have per "X" amount of fuel, the lean it is....


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Old 07-29-2003, 11:47 PM   #11
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

It is my understanding that the real advantage to reverse flow cooling is twofold, the hotter block temps greatly reduce piston/ring to cylinger wall friction, and you can raise compression further with the cooler running heads ? This is according to Smokey Unick (sp? )
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Old 07-30-2003, 12:04 AM   #12
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

Yes but Smokey yunick was talking about a GEN II
S/B Chevy engine,NOT an LS1....

I'd run the Meziere until more testing is done......

JS
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Old 07-30-2003, 12:06 PM   #13
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

Read the post again CamaroGuy. J@work clearly states, "In rough numbers a ratio of 15 to 1 for emissions and 14.3 for economy." Now you tell me how 14.3:1 is ideal for fuel economy.
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Old 07-31-2003, 08:03 AM   #14
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

Quote:
30thWS6 is the closest so far. You need heat in the heads to make the engine work right. Emissions performance and street performance (that would be the combination of fuel economy and performance) are very close. In rough numbers a ratio of 15 to 1 for emissions and 14.3 for economy. If the heads are always cold the engine is going to be looking for a 11.5 to 12.2 range to run correctly. This number is pretty close to the perfect full throttle acceleration ratio but. With the head at operating temperature. So when does reverse cool make sence? When the combustion temps will create other problems. The LT1 engine was reverse cooled to combat pre ignition the higher compression ratio was going to cause. When the computers got smarter they found they could bring up the head temps and keep the compression up. I can see no advantage to reverse cooling a car that has an average operating temperature above 165 degrees that is going to run for more than a few seconds. Another reason to not reverse cool the LS1 is: If you carefully look at the cooling passages, you will find a "built in" restriction as the water travels the normal direction. If you reverse this you will not be able to create much if any jacket pressure and on this engine that is more critical than any other GM engine ever produced so far. If you are running the "big bore" sleeves I believe reverse cooling would be harmful to the rear cylinders. Without good water jacket pressure and the cooling system circulating in the designed direction I feel the cooling system would ignore some of the hard to get to areas in the block. Sorry for the long winded post....but that is a very important matter.
First of all, you have to put a temp number to your statement...

"You need heat in the heads to make the engine work right."

Your way off base with this statement too..

"If you carefully look at the cooling passages, you will find a "built in" restriction as the water travels the normal direction."

You have no clue how our unit works, do you think I'm circulating the coolant through the radiator backwards too?

Iv'e run mine for over 2 years now and tested on at least 8 different cars, if there was going to be a problem, I would have known about this problem a long time ago.


Were being independantly tested right now, all the test data will be vs another EWP and will be released as early as the end of next week. Granted... everyone's entitled to there *opinion, as long as it's factually based meaning the posting member has enough knowledge/experience to speak eliquently and support more accurate AF ratio representations IMO. A complete understanding of cooling dynamics of an Aluminum internal combustion engine to begin with is a plus and must have first hand knowledge of temp split data points to compare there facts to. Knowledge of reverse vs and or conventional cooling fundimentals are a must to render a more accurate comparison other than ones armchair assessment. I'm not blatently stating "you don't know what your talking about" but your above post kinda speaks for it's self..

JP
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Old 07-31-2003, 08:12 AM   #15
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

I still don't understand why the 1998 Pontiac Firebird Brochure specifically called out "Reverse Flow Cooling" for the LS1's...

Joe, I await your results also. I'm on the fence for JPR vs. Mez. I will be going electric tho.

-Andrew
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Old 07-31-2003, 10:01 AM   #16
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

And some of the early LS1's came with one big V8 style coil pack in 98 on there crate motors but does that mean it worked as well as the final designed setup which is coil on plug?

I dont know as I'm not smart enough to answer this question but look at the C5R Corvette race team,I would think these boys have the FUNDS/R&D to find out if these things really work.

What type of pump do they run?
I think its a standard pump but thats all they've had until now.
Maybe there not allowed to use an ewp?

The point is that a EWP can and will work and the reverse idea is a good one for sure.Like Joe said,Its being tested so we can all wait to see if it worth anything over a standard or ewp.

I'm curious too.
U figure with a 7 to 10RW gain from the pump and 12 to 15RW from this new intake and we could see 470RWHP 6sp H/C cars

The only thing that confuse me....
The LS1 combustion chamber is soooo efficent that u dont need more timing to make power,Generally 25 to 30 of adv. is all thats required on an LS1.So would a cooler comb. chamber with the ability to use more timing make more power or would just cooling the comb. chamber and still running 25 to 30 degree's of timing make more power?

Parasitic loss of the standanrd GM pump over an EWP I can see,The other stuff is vague to me.I'm not that smart to answer this stuff but it would be kewl to get an answer to my question?
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Old 07-31-2003, 04:17 PM   #17
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

I could see a larger advantage of runnin reverse cooling on stock compression forced induction engines as a crutch before using lower compression forged internals.
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Old 07-31-2003, 08:27 PM   #18
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

ttt
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Old 08-22-2003, 03:07 PM   #19
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

So... three weeks later... any results? or are you having problems? I'm seeing all of these nice results with the new Meziere and need to know if the JPR reverse-cooled is better. I'm guessing that further dyno testing(tweaking) will be needed to show this one makes more power? Just trying to get a little blood boiling out of JPR so can hear some results.

Question - In theory, which style cooling would be better for a daily driver or roadrace car that sees more use than a 1/4 mile contender?
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Old 08-22-2003, 03:17 PM   #20
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Default Re: Reverse cooled vs. standard flow water pumps on LS1's

I probably shouldn't speak for Joe...but when initial testing was done on his reverse-cooled EWPs (at least 1 or 2 years ago now) he saw gains of like 13-25 RWHP. I know 13 HP was the smallest gain seen. It is also lighter than the Meziere, so it should be a superior product, IMO. The question is: when is JPR going to release it? What about it, Joe?
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