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Reversing the coolant circulation direction
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Author:  olafla [ Mon Jul 07, 2014 8:36 pm ]
Post subject:  Reversing the coolant circulation direction
Has anyone been experimenting with reversing the direction of the coolant flow through a SL6 engine, or know anything about such trials?

Olaf
Author:  Old6rodder [ Mon Jul 07, 2014 8:58 pm ]
Post subject: 
Not exactly.

No idea if this'll help whatever you're considering, but here 'tis ......

On the 'Brick I needed to run a radiator behind the engine.
I closed off all the passages between the head and block, routed the water pump's inlet from the front of the head, added water necks to the back of the head and block (with thermostat & sensor at the block one), and hooked the radiator up back there.

Water flow is from the pump through the block (front to back, normal direction, but no flow to the head), out the back to the radiator, then back through the head (back to front, normal direction, but no flow to the block), and out the front to return to the pump.
Author:  Reed [ Mon Jul 07, 2014 9:26 pm ]
Post subject: 
All you would need to do is reverse the rotation of the pump and build a reversed impeller for the water pump and press it on the shaft.

Serpentine belt installation?
Author:  emsvitil [ Mon Jul 07, 2014 11:28 pm ]
Post subject: 
Quote:
All you would need to do is reverse the rotation of the pump and build a reversed impeller for the water pump and press it on the shaft.

Serpentine belt installation?
water flow thru the engine would be the same............
Author:  Greg Ondayko [ Tue Jul 08, 2014 5:20 am ]
Post subject: 
I think some of the marine 225's may have been setup to run in reverse..

Maybe not.. I am no marine engine expert.

But if they did how would the water pump have been designed?


Greg
Author:  Reed [ Tue Jul 08, 2014 7:43 am ]
Post subject: 
If the pump pulley spun counterclockwise instead of clockwise and the impeller on the back was "mirrored" to operate counterclockwise then the water would flow the other direction.

I had to do this on the engine in my 89 Ford van when I converted it from carburetion to fuel injection. For various irrelevant reasons I had to switch from the accessory belt setup the motor was built with to the later serpentine belt system. The serpentine belt system spins the water pump in the opposite direction than the older V-belt system. The water pump and timing chain covers were identical, but the serpentine belt impeller was a mirror image of the v-belt impeller. Everything else in the cooling system is the same as the stock v-belt system, even the radiator. Of course, this is in a v-8, not an inline, so the cooling system may flow a bit differently.

Remember that guy in Alaska who converted his slant to a serpentine belt system? How did he deal with the water pump drive issue?
Author:  Joshie225 [ Tue Jul 08, 2014 8:14 am ]
Post subject: 
Reed,

All centrifugal pumps have the inlet at the center and the outlet at the periphery.
Author:  olafla [ Tue Jul 08, 2014 8:15 am ]
Post subject: 
I am toying with the idea to go all electric on accessories, el. power steering pump, and el. water pump, where the pump speed should be temperature controlled. That also gives me the possibility to reverse the coolant flow, if that is an improvement for the SL6. Most modern engines have flow in the other direction compared to the SL6, but I wonder if reverse flow would improve or worsen the cooling of the cylinder head.
Could the chances for warping increase because the cooler water enter the front of the head, while the rear portion is hotter?
The thermostat would also have to be relocated. Correction/clarification: A temperature controlled pump don't need a separate thermostat, but would a temp. reading be correct when flow is reversed?
Any thoughts?

Olaf
Author:  Joshie225 [ Tue Jul 08, 2014 8:24 am ]
Post subject: 
General Motors used reverse flow cooling (heads then block) on the Gen 2 small block also known as the LT1. Steam vents were required in the cylinder heads. They abandonded this for the Gen 3 (LS series) engines.

International Harvester knows a few things about keeping a hard working engine cool. Their SV engines (except for the late 392) send water into the front of the head to cool the exhaust side of the head, flow is down into the block, around the cylinders, up through the intake side of the heads and out through the intake manifold. The improved cooling 392 changed this to cool the cylinders first as the siamese cylinders didn't cool as efficiently as the smaller engines with full water jackets around the cylinders.

Chrysler made a heavy duty version of the 225 and as far as I know retained the same coolant flow as in lighter duty versions.

So what's the goal?

I really like Dick's rear radiator setup. I'll keep that in mind if I ever do a slant six powered mid-engine car of my own.
Author:  Old6rodder [ Tue Jul 08, 2014 9:27 am ]
Post subject: 
From the radiator/block/head frame of reference, the 'Brick's reversed. Though the water flows through each part in the normal directions, their relative positions in that flow're different.

While the pump's also "re-located" (technically), it only provides power to the system (hydraulically speaking), and has no effect on cooling beyond flow speed & volume.

Stock: radiator - block - head
'Brick: radiator - head - block

I've noticed no difference in cooling capacity or rate with this set-up vs El Toad's stock set-up, and've had'er idling in gear for an hour+ (while shaving the hides' crowns :wink:).

A possible variation of this rear feed idea, using an electric pump at the back, would keep the head/block passages open. You'd estimate flow rates between the head & block at the front and rear of course, and adjust the holes accordingly, but that'd be a small cobble.

To re-address the original question; from my own work I've seen no easily discernable difference in head-first vs block-first flow on my slants.
Author:  Danarchy [ Tue Jul 08, 2014 9:41 am ]
Post subject: 
Back when I was a 2-stroke junky, I worked on alot of DKW's (and SAAB) cars. The DKW was not reverse flow(and had no waterpump), but the radiator was mounted at the back of the engine. It work on the thermosiphon principle, and worked very well!
-What would be the benefit of reverse flow?

Image
Author:  Reed [ Tue Jul 08, 2014 12:44 pm ]
Post subject: 
Quote:
Reed,

All centrifugal pumps have the inlet at the center and the outlet at the periphery.
D'OH! I wasn't thinking clearly I guess. Now that you say it of course it wouldn't make a difference. I'll go put my dunce cap on and sit in the corner for a while. :oops: :oops:
Author:  olafla [ Wed Jul 09, 2014 5:07 am ]
Post subject: 
Quote:
So what's the goal?
Quote:
-What would be the benefit of reverse flow?
Well, that's what I ask you guys!

I think that one possible benefit - on a modern engine - could be quicker heating of the whole engine, to bring it sooner into it's normal temperature operating range, which may be beneficial from an environmental viewpoint. The engine designers operate with very small numbers these days, when it comes to improving fuel efficiency!
Quote:
To re-address the original question; from my own work I've seen no easily discernable difference in head-first vs block-first flow on my slants.
That is a good answer, and exactly what I was looking for.

From your comments so far, there don't seem to be any obvious benefits from reversing the coolant flow in a stock SL6 engine, so if I go electric, I guess I'll keep the original flow direction. :D

Olaf
Author:  Dart270 [ Wed Jul 09, 2014 6:14 am ]
Post subject: 
This would run the head a bit cooler than it would be in std configuration, and put more heat into the block jacket. This should be good for keeping detonation down and still having relatively high coolant temp for low wear on the cylinders. You might be able to run more advance for a given average coolant temp.

Lou
Author:  olafla [ Wed Jul 09, 2014 6:14 pm ]
Post subject: 
Lou, thank you. What about warping, do you think it could be an issue?

Olaf
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