Slant Six Forum
https://slantsix.org/forum/

water pumps
https://slantsix.org/forum/viewtopic.php?t=57295		 Page 1 of 3
Author:  '67 Dart 270 [ Mon Mar 16, 2015 11:02 am ]
Post subject:  water pumps
Here is a picture of an aftermarket water pump (left) and a rebuilt Chrysler unit (right).

http://s785.photobucket.com/user/67dart ... sort=3&o=0

Notice the difference in the ribbing, weep hole diameter, thickness of the body at the neck where the shaft goes in.

Below is a pic of the blades:

http://s785.photobucket.com/user/67dart ... sort=3&o=1

Note the after market one has 8 blades and the Chrysler one has only 6 blades.

This is the interesting part, the blades are facing in different directions. Assuming my slant only rotates the blades in a one direction, does it not matter which way these blades face? Seems like one way might be better at moving fluid than the other....

brian
Author:  Pierre [ Mon Mar 16, 2015 11:58 am ]
Post subject: 
The blades appear to be going the same direction to me, it's the fold on top of the blade that's bent in the opposite direction.

Are you sure either one is an oem pump? The oem pumps I've seen have a square pulley flange, not a round one.
Author:  '67 Dart 270 [ Mon Mar 16, 2015 12:30 pm ]
Post subject:  answers...
No, I'm not sure but there is a pentastar on the unpainted one. Perhaps a copy, who knows...

Not only are the folds facing differently, but the blades are angled differently, i.e. the painted one (bottom) has blades angled counter clockwise, and the top one has blades angled clockwise.
Author:  Pierre [ Mon Mar 16, 2015 12:55 pm ]
Post subject: 
Ok, maybe its an optical illusion then.

Fair enough about the pentastar pump. Perhaps they changed as time went. But I know the older oem pumps had ... sorry, that should have been cross shaped flange, not square.

Besides the dual engine marine application they do rotate the same direction. I recall someone else on here saying for this type of pump it doesn't matter what direction, fluid direction will be the same. As for efficiency I can't be sure.
Author:  SlantSteve [ Mon Mar 16, 2015 2:06 pm ]
Post subject: 
I've heard it mentioned that some of the aftermarket pumps have 8 vanes while others have 6.. Same part number,same supplier. I think it was DOC who mentioned the 8 vane is preferred ,but over here I've only seen the 6 vane aftermarket impellers with the brand GMB cast on the housing and they seem OK. The (I assume) earlier genuine pump castings are different again to the one you have,they had a semi circular section cast under the seal drain hole,I assume to help direct coolant to a more obvious spot when the seals did finally leak. The last pump I used was a reman unit with the correct housing,but it only had the 6 vane impeller and it works fine. Another type of impeller used has a flat disc on the back,they were cast iron and some were plastic,this was the factory original design. I've heard it said these are better for avoiding cavitation and if you look at an Edelbrock impeller I believe they are this design,I also have heard of guys welding flat plates to the back of the stamped style impellers to give them better high rpm performance in other brand engines,but I've never done it personally. I'd tend think that your 8 vane pump may be better at low rpm but the 6 vane may be better at higher rpm,bit the different shaped vanes may make a difference as well... :roll:
Author:  emsvitil [ Mon Mar 16, 2015 2:19 pm ]
Post subject: 
The blades should angle back a little from the direction of rotation.

This one should rotate counter clockwise:

Image
Author:  SlantSixDan [ Mon Mar 16, 2015 3:51 pm ]
Post subject: 
It doesn't matter which direction the impeller vanes are folded. They're radial to the shaft axis and they're not curved, so they work the same whichever way the impeller is spun.
Quote:
I've heard it mentioned that some of the aftermarket pumps have 8 vanes while others have 6.. Same part number,same supplier. I think it was DOC who mentioned the 8 vane is preferred
I remember it the other way (6 preferred) but I could be wrong. Rather than any of these stamped-steel impellers I prefer the solid impeller, either cast iron or phenolic with a cast iron hub insert, the factory used through '67.
Quote:
The (I assume) earlier genuine pump castings are different again to the one you have,they had a semi circular section cast under the seal drain hole,I assume to help direct coolant to a more obvious spot when the seals did finally leak.
No, it was to prevent flung crud from clogging the weep hole. Factory pumps had this weep hole shield starting in 1964.

I'd like to see someone (imagine me looking in the direction of Sunnyvale) come forth with an up-to-date curved-vane impeller.
Image
Author:  '67 Dart 270 [ Mon Mar 16, 2015 4:01 pm ]
Post subject:  I agree..
Ed,

You're right, which makes me think the non-painted one with the pentastar is a better design for flow, but I'm no fluid dynamics expert by any means. I'll ask my wife, she's into physics...I bet she remembers Bernoulli's Equation on fluid flow by heart. On second thought, I think that involves laminar flow through a pipe, no turbulence...we're dealing with turbulence here...hmmm. Like I said, I'll ask my wife. :oops:

brian
Author:  '67 Dart 270 [ Mon Mar 16, 2015 4:12 pm ]
Post subject:  6 vs 8
Dan,

I think you might be right about 6 being better than 8... :D

OK, enough double entendre's, what I meant to say was that it seems intuitive to me that if you have too many blades it could be inefficient and that not enough blades is also inefficient.

Theoretically, the optimum blade is the biggest one possible (more swept area = more thrust or material moved, in this case coolant). More blades do not necessarily produce more thrust, as the wake of each blade can interfere with trailing blades. Think of one with 50 blades, wouldn't likely move fluid as well (would it?).

What do you think the odds are that the various aftermarket water pump refurbishers actually cared about meeting Ma Chrysler's flow specs for the water pumps? Maybe I suppose, they are all similar, but intuitively (in my strange mind) the 6 blades would not have wakes interfering with neighboring blades as much as the 8 blade one...that and I have this nagging superstition that 6 is better than 8...

brian
Author:  emsvitil [ Mon Mar 16, 2015 4:21 pm ]
Post subject: 
Although the blades aren't curved, they should be a linear approximation of the curved blade so the water is flung off the end of the blade rather than being captured by the blade.......

This is what you usually see:

Image


If this blade was rotated CCW, the flinging of the water would be fighting with the cupping/capturing of the water.........
Author:  SlantSixDan [ Mon Mar 16, 2015 4:41 pm ]
Post subject:  Re: 6 vs 8
Quote:
What do you think the odds are that the various aftermarket water pump refurbishers actually cared about meeting Ma Chrysler's flow specs for the water pumps?
Odds round up to zero on that one. They use whatever ø3½" impeller they happen to have a lot of.
Author:  SlantSixDan [ Mon Mar 16, 2015 4:42 pm ]
Post subject: 
Quote:
Although the blades aren't curved, they should be a linear approximation of the curved blade so the water is flung off the end of the blade rather than being captured by the blade
One doesn't follow from the other. The pre-'68 (cast) impellers all had radial blades, perfectly orthogonal to the shaft axis, and they work just fine. I don't have a slant-6 stamped-steel impeller to look at right now (the one you show in the pic is not one I've seen on slant-6 water pumps, have you?), but my recollection has the stamped-steel blades likewise orthogonal.
Author:  emsvitil [ Mon Mar 16, 2015 4:52 pm ]
Post subject: 
Just so they're not angled forward........


:wink:
Author:  '67 Dart 270 [ Mon Mar 16, 2015 5:26 pm ]
Post subject:  angled forward...
Yes, but Ed the one in the pic I posted, the painted one, does have the blades angled forward relative to rotation. They rotate CCW from the perspective shown, the slant runs clockwise facing the engine from front.

In the thread below, on page 16, DD shares some water pump impeller wisdom and shows a few designs. He shows a couple 6 blade impellers (one he cut off three blades) and it's interesting one has the blades angled CW and the other angled CCW....hmmm...

http://www.slantsix.org/forum/viewtopic ... 2df7da38a8

brian
Author:  emsvitil [ Mon Mar 16, 2015 5:52 pm ]
Post subject: 
The non-bent up part of the blades doesn't count.
(although I think the blade type that's on the tri is more efficient.....)


Your 6 blade looks straight, I can't tell on the 8.
Page 1 of 3 All times are UTC-07:00
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/