Has anyone seen any real benefit from reverse flow cooling to justify the swap?
Anyone run it on the street? Obviously it should keep the heads cooler, but are there any issues w/ overall cooling while street driving?

I'm thinking it may be a benefit to a timing sensitive nitrous combination due to keeping the heads a little cooler.

Any input?

Cavitation from flowing backwards is what keeps this from being a viable option. It really needs to be designed for the direction of flow to see any benefit.

Is that an issue for reverse flow in general? Or certain setups? Excuse my ignorance, this isn't something I have any experience with.
If you were to use the Indy plate and chevy pump, does that have cavitation issues?

i have the Mezzaire reverse flow pump. it does take a bit of work to get the air out of the system but once done it works great

I had looked into this a few years ago. Some testing done by some well known engine guys showed cavitation issues that were causing hot spots that weren't present when flowed in the direction designed. It might be possible to extrude hone the water passages in the direction of flow your wanting to run, which may resolve the issue, but you'd be experimenting!

If the water is introduced into the heads as high as possible, you could see an improvement. The Indy set up tries to force the water up into the heads. That's the problem.

OK, thanks for the info fellas! It looks like the Meziere or CSR one piece reverse pump is the way to go. Very clean looking setup. I managed to find an old thread on here about it just a minute ago and some said the whole reverse flow setup is a waste.

Is this a wedge head or Hemi?

I was thinking about it for my hemi.

My

I ran the reverse flow for 6 yrs on the street with a 499", ported Indy -1's, ported Indy intake, & a 1050 dom in a tube chassis. Biggest ATCO radiator at the time, with twin 12" SPA fans. Never ran more than 1 fan at a time. Never used a fan on the road. Could be stuck in traffic on a hot day, no problem with 1 fan. Don't remember "having" to use both fans for anything. I would typically turn on 1 fan before arriving to town so as not to forget, would add the 2nd fan to supper cool just before arriving at a local cruise for shut down. Best cooling system I ever set up, to that time.

That being said the only 2 issues I had where pump related. The 1st pump was used because I robbed it off of one of my other cars while it was without motor. That pump died after about 5 yrs of total use. It was a 30gph iirc. When I replaced that I put the 35gph in. Only issue I had with that pump was with a long extended 3500 rpm trip where the water speed could not keep up with the heat being produced. Backed of the rpm a little & the water temp came down.

My next pump was going to be a 55gph Meziere, though I never got to that. Had a flat tire on a roller lifter, & stayed focused on a full restoration on another car. Would've liked to have put that 55 in to test that 3500 rpm trip again.

ymmw.

Remote pump is the easiest way. A 1/8" pipe hole in top of housing for a jumper hose to top portion of tank on radator. This insures any air pocket entering pump is purged.

If you purge air when filling your system the close it off you could get low on coolant and cavitate pump. By constantly purging this cannot happen.

Thanks Mezeire for the tip.

I have a 528 cube BB in my bracket car with the reverse flow plate from Indy and Meziere pump plus a large rad with single fan and shroud. I run alky, and heat the motor up over 200 to clear the oil plus warm it up to run. If I need to drop the temp quickly, I just run the pump and fan, engine shut off. I can literally watch the engine temp drop and within three or so minutes it is down below 140 if I don't keep an eye on it closely and shut it off. I don't know for sure about gains, but If they are there I would guess the gains would be better on gas than alky due to the cooling from alky. I run Felpro race gaskets which have small slots instead of big holes in some of the passages, which must help even out the flow between the different cylinders? As far as cavitation, my electric pump sounds well loaded and consistent, and the flow when looking in the radiator filler neck looks great.
There must be a good reason to run water through the heads first. For starters, that is where most of the heat is, obviously. I understand some of the new engines have gone that route.

...First I like the smooth transitions that pump you mentioned has over the poorly adapted SBC retrofit pump. Also, I think there would be gains in a more uniform temperature distribution if you added small .250" holes to the gaskets, (at the bottoms of paired cyls 13 57 24 68) thereby connecting the head orifices to the block orifices. Just look at the coolant path and judge for yourself. Ive not seen a gasket that does this. At lower speeds air will inherently try to travel along the highest parts of the cavities, FYI.

On our hemi we were never able to get all the air out of the system when we tried the reverse cooling. There would be pressure in the system for days after the last time it ran. Switched back to conventional flow and it was fine. I imagine it would vary for different head/block castings tho.

For those saying it doesn't work in a street car... every GM LT1 motor from the 90s was reverse flow. My friends daily driver trans am has a built LT4 with 13:1 compression, drives everywhere and sprays it on pump gas. I don't think that would work with standard flow. Food for thought

The engine was designed for it...
Much different than trying to get an engine that wasn't designed to have that type of cooling system work.
Lt1 block is different, as are the heads, from a conventional sbc.
It was designed as a reverse cooled engine.

this sounds interesting. do you, by chance, have a pic or two of this setup ? TIA.

Reverse cooling is always better from a performance standpoint. The only reason it is more difficult on a BBM is the flow path. Has nothing to do with the heads, the block, being designed for it or anything else. It is simply that fact that the water has to flow up first the way the water has to enter the heads. Larger pumps help

The BEST way to do it in a race car application is use a remote pump as Leon pointed out and pump the water in the end of the heads. Bypass the dog leg in the block period

My 499 has the Indy reverse flow plate and a CSR pump, and uses AN-12 lines from both sides to the rad to the pump on each side. It also had the adapter plumbed with AN-6 lines to the B1 heads at the center ex ports, so that area gets cool water. Never had any issues with air pockets (that I know of). Got kinda warm on the street in the summer but it was 16-1 and the rad is pretty small and I had a pusher elec fan.

Changes made to the LT1 block and heads were minor. The block had two water passages on each side, one atop the other, looking like a BBM. The upper hole on each side was the water inlet. The top corner coolant hole was opened up on both head and block to allow for this. The heads did have some small ports at the top of the head water jacket in the rear of the engine, these were to let air or vapor out. The coolant passages that route the coolant through the intake manifold to the center thermostat were blocked off.

Many pairs of LT1 heads have been converted to work on first generation smallblocks. The biggest problem is closing the huge holes in the upper corners of the heads. Second is routing water from the head into a thermostat chamber.

R.