S2 water pump is factory underdriven
07-20-2011, 07:37 PM
#1
S2 water pump is factory underdriven
I have been fooling around with the cooling systems on our cars for some years now. Some weeks ago I came to the conclusion that our(S1) water pump needed to be at a different gear ratio than what it currently is. I have been thinking about this for a while now and today I discovered something. Look at the picture. The bigger water pump pulley is from the s2 model.
Now the pulley at the e shaft is the same size as the s1. That means that Mazda decided to underdrive the water pump. Now remember--the S2 water pump has a different designed impeller so cavatation wasnt an issue like before so that wasnt the reason they did this? Now why did Mazda do this?
I have an idea.
https://www.rx8club.com/attachment.p...1&d=1311208578
Now the pulley at the e shaft is the same size as the s1. That means that Mazda decided to underdrive the water pump. Now remember--the S2 water pump has a different designed impeller so cavatation wasnt an issue like before so that wasnt the reason they did this? Now why did Mazda do this?
I have an idea.
https://www.rx8club.com/attachment.p...1&d=1311208578
07-20-2011, 08:22 PM
#5
That is a good point. If you look close, it seems like the perimeter of the S2 pulley is thicker. The "cup" part in the middle looks to have the same diameter though. And most noticeably would be the offset distance of the holes and the circumference of the s2
07-20-2011, 09:51 PM
#6
Super Moderator
So what is your idea....??
Just some Parts History...
As we know the S2 Water Pump is different, uses an O ring to seal onto the different S2 Housing and Timing Cover-front alloy Housing.
S2 Impeller is a hard grey plastic.
vvvvvv Belt is different.
Water Pump Pulley is different as you point out, obviously a slightly larger diameter.
E-Shaft Pulley Set by Part Number is also different (N3R1-11-400A).
So my idea is at higher RPM the S2 pulley therefore Impeller does not spin as fast as S1, therefore it may or will help-prevent 'cavatation'??
Is that what your were thinking OD??
IMO the RPM difference would be minor...wouldn't it??, but also I think the Impeller Shaft in S2 is also larger in diameter to the S1.
Just some Parts History...
As we know the S2 Water Pump is different, uses an O ring to seal onto the different S2 Housing and Timing Cover-front alloy Housing.
S2 Impeller is a hard grey plastic.
vvvvvv Belt is different.
Water Pump Pulley is different as you point out, obviously a slightly larger diameter.
E-Shaft Pulley Set by Part Number is also different (N3R1-11-400A).
So my idea is at higher RPM the S2 pulley therefore Impeller does not spin as fast as S1, therefore it may or will help-prevent 'cavatation'??
Is that what your were thinking OD??
IMO the RPM difference would be minor...wouldn't it??, but also I think the Impeller Shaft in S2 is also larger in diameter to the S1.
07-21-2011, 08:36 AM
#8
The s2 pulley will not fit on the S1. I did not measure because it was obvious just by looking that it was bigger.
I do believe that the impeller design is also different than the S1--it favors the mazmart one--if I am not mistaken.
Now the S2 model is designed to operate at an adverage higher rpm than the S1 due to its gearing, I believe this underdrive pulley was part of that package to help cool the engine because of the increased heat the adverage higher rpms would produce?
I am ready to get flamed on this, but the S1 pump moves more coolant in the lower rpms due to its impeller design , but it does cavatate in the higher rpms. The newer impeller design ( mazmart or the s2) moves less coolant during the lower rpms ( below 3K) but does flow more beyound that.
What does that mean? Well here is my thoughts. A cooling system basically needs 3 things to function well. 1--coolant flow, 2-- air flow through the radiator, 3--a big enough radiator face to adequently cool the flowing coolant.
Now it gets a lot more complicated, but that are the basic needs.
If one area of those basic needs are compromised then the other areas can to a degree, compensate. For example--if you have limited airflow a bigger radiator face can compensate.
Now Mazda knows low speed cooling is a problem area in hot climates. So they improved the air supply to the coolers ( coolant and oil), they improved the fans, the water pump impellar and now with od detective work we see they are underdriving the water pump. They also did some other stuff that I will not get into at this point. This new approach to this problem area seems to be working?
They knew low speed cooling needed improvement, they knew the old waterpump design caviates in the higher rpms AND maybe they found that the new impeller also cavitates some in the higher rpm, so they undrove it. The fans and airsupply helps with the low speed cooling. The underdrive pulley helps with high speed cooling (cavitation).
Kinda makes sense to me. So maybe even the mazmart pump needs an under drive pulley? Its already know we can use better fans.
I do believe that the impeller design is also different than the S1--it favors the mazmart one--if I am not mistaken.
Now the S2 model is designed to operate at an adverage higher rpm than the S1 due to its gearing, I believe this underdrive pulley was part of that package to help cool the engine because of the increased heat the adverage higher rpms would produce?
I am ready to get flamed on this, but the S1 pump moves more coolant in the lower rpms due to its impeller design , but it does cavatate in the higher rpms. The newer impeller design ( mazmart or the s2) moves less coolant during the lower rpms ( below 3K) but does flow more beyound that.
What does that mean? Well here is my thoughts. A cooling system basically needs 3 things to function well. 1--coolant flow, 2-- air flow through the radiator, 3--a big enough radiator face to adequently cool the flowing coolant.
Now it gets a lot more complicated, but that are the basic needs.
If one area of those basic needs are compromised then the other areas can to a degree, compensate. For example--if you have limited airflow a bigger radiator face can compensate.
Now Mazda knows low speed cooling is a problem area in hot climates. So they improved the air supply to the coolers ( coolant and oil), they improved the fans, the water pump impellar and now with od detective work we see they are underdriving the water pump. They also did some other stuff that I will not get into at this point. This new approach to this problem area seems to be working?
They knew low speed cooling needed improvement, they knew the old waterpump design caviates in the higher rpms AND maybe they found that the new impeller also cavitates some in the higher rpm, so they undrove it. The fans and airsupply helps with the low speed cooling. The underdrive pulley helps with high speed cooling (cavitation).
Kinda makes sense to me. So maybe even the mazmart pump needs an under drive pulley? Its already know we can use better fans.
07-21-2011, 09:06 AM
#9
The s2 pulley will not fit on the S1. I did not measure because it was obvious just by looking that it was bigger.
I do believe that the impeller design is also different than the S1--it favors the mazmart one--if I am not mistaken.
Now the S2 model is designed to operate at an adverage higher rpm than the S1 due to its gearing, I believe this underdrive pulley was part of that package to help cool the engine because of the increased heat the adverage higher rpms would produce?
I am ready to get flamed on this, but the S1 pump moves more coolant in the lower rpms due to its impeller design , but it does cavatate in the higher rpms. The newer impeller design ( mazmart or the s2) moves less coolant during the lower rpms ( below 3K) but does flow more beyound that.
What does that mean? Well here is my thoughts. A cooling system basically needs 3 things to function well. 1--coolant flow, 2-- air flow through the radiator, 3--a big enough radiator face to adequently cool the flowing coolant.
Now it gets a lot more complicated, but that are the basic needs.
If one area of those basic needs are compromised then the other areas can to a degree, compensate. For example--if you have limited airflow a bigger radiator face can compensate.
Now Mazda knows low speed cooling is a problem area in hot climates. So they improved the air supply to the coolers ( coolant and oil), they improved the fans, the water pump impellar and now with od detective work we see they are underdriving the water pump. They also did some other stuff that I will not get into at this point. This new approach to this problem area seems to be working?
They knew low speed cooling needed improvement, they knew the old waterpump design caviates in the higher rpms AND maybe they found that the new impeller also cavitates some in the higher rpm, so they undrove it. The fans and airsupply helps with the low speed cooling. The underdrive pulley helps with high speed cooling (cavitation).
Kinda makes sense to me. So maybe even the mazmart pump needs an under drive pulley? Its already know we can use better fans.
I do believe that the impeller design is also different than the S1--it favors the mazmart one--if I am not mistaken.
Now the S2 model is designed to operate at an adverage higher rpm than the S1 due to its gearing, I believe this underdrive pulley was part of that package to help cool the engine because of the increased heat the adverage higher rpms would produce?
I am ready to get flamed on this, but the S1 pump moves more coolant in the lower rpms due to its impeller design , but it does cavatate in the higher rpms. The newer impeller design ( mazmart or the s2) moves less coolant during the lower rpms ( below 3K) but does flow more beyound that.
What does that mean? Well here is my thoughts. A cooling system basically needs 3 things to function well. 1--coolant flow, 2-- air flow through the radiator, 3--a big enough radiator face to adequently cool the flowing coolant.
Now it gets a lot more complicated, but that are the basic needs.
If one area of those basic needs are compromised then the other areas can to a degree, compensate. For example--if you have limited airflow a bigger radiator face can compensate.
Now Mazda knows low speed cooling is a problem area in hot climates. So they improved the air supply to the coolers ( coolant and oil), they improved the fans, the water pump impellar and now with od detective work we see they are underdriving the water pump. They also did some other stuff that I will not get into at this point. This new approach to this problem area seems to be working?
They knew low speed cooling needed improvement, they knew the old waterpump design caviates in the higher rpms AND maybe they found that the new impeller also cavitates some in the higher rpm, so they undrove it. The fans and airsupply helps with the low speed cooling. The underdrive pulley helps with high speed cooling (cavitation).
Kinda makes sense to me. So maybe even the mazmart pump needs an under drive pulley? Its already know we can use better fans.
07-21-2011, 09:26 AM
#11
FULLY SEMI AUTOMATIC
iTrader: (9)
would this mean that an ud pully set on a s1 isnt a complete waste of $?
07-21-2011, 03:20 PM
#13
Then again, nobody really measures, collects data, or even adheres to anything close to objective scientific methodology around here anymore, do they?
Don't argue with me about this. I am a full-time professional.
07-21-2011, 03:43 PM
#14
Registered
Not having test data doesn't make the guess wrong. It is just an unknown.
Perhaps this thread will trigger someone to actually perform a flow test or dig up the results of one.
Perhaps this thread will trigger someone to actually perform a flow test or dig up the results of one.
07-21-2011, 04:00 PM
#15
Super Moderator
I do believe that the impeller design is also different than the S1--it favors the mazmart one--if I am not mistaken.
The new S2 w pump I have in my hand definitely has the hard plastic impeller.
07-21-2011, 04:04 PM
#16
Super Moderator
The Fan Motors have been changed, NOT the Fan Blades.
Plus the extra fan speed controlled by PCM and extra Relay.
And before anyone asks you can not put an S2 pump on a S1 (without modifications to the S2 Pump stud hole and new Pump Pulley).
Plus the extra fan speed controlled by PCM and extra Relay.
And before anyone asks you can not put an S2 pump on a S1 (without modifications to the S2 Pump stud hole and new Pump Pulley).
Last edited by ASH8; 07-21-2011 at 04:07 PM.
07-21-2011, 06:13 PM
#17
well I'm surprised you haven't just installed a Davies Craig electric pump into the suction hose and let it serve as a booster pump to the OE system, assuming you don't just eliminate the OE pump impeller and bypass the pump pulley drive which is not that hard to do. In either case any cavitation is eliminated plus all the other benefits. It hangs right in the hose, no hard mounting. Slap in their digital controller too. Doesn't get any easier than that. If it was allowable in the class I run in I'd have done it years ago.
07-21-2011, 08:12 PM
#18
Dan has done it but he has not shared any data with us, he does indicate that it is working well for him. I have seen that pump being used for a booster low speed cooling pump, but not as a standalone on some recip engines locally.
I am not convinced that the electric pump will develop and hold the pressure I want to have in the cooling system.
Guys it an hypothesis, if yall read what i posted thats all I said. A lot of discoveries begin with an hypothesis after observations. I think my reasoning is logical, but it certainly is not proven.
Take it for what it is worth to you.
Ash thanks for clarifying the shape and composition of the s2 water pump impeller.
You know Mazda doesnt change things without a reason. It does make you wonder why they changed this?
I think most folks here do realize that most mechanical water pumps are grossly overdriven. They have to be in order to provide proper pressure and flow in the lower rpms. So its a catch 22 situation. Since the pump is engine rpm dependent --it cannot be avoided.
Now if they could only get an electric water pump that can hold the pressure needed, give enough flow and not require a small power plant to do it then we will be good.
Of course you can choose to run Evans coolant and a pressure less system. An EWP will do great in that kind of set up.
If I keep guessing I am going to get something right--sooner or later
I am not convinced that the electric pump will develop and hold the pressure I want to have in the cooling system.
Guys it an hypothesis, if yall read what i posted thats all I said. A lot of discoveries begin with an hypothesis after observations. I think my reasoning is logical, but it certainly is not proven.
Take it for what it is worth to you.
Ash thanks for clarifying the shape and composition of the s2 water pump impeller.
You know Mazda doesnt change things without a reason. It does make you wonder why they changed this?
I think most folks here do realize that most mechanical water pumps are grossly overdriven. They have to be in order to provide proper pressure and flow in the lower rpms. So its a catch 22 situation. Since the pump is engine rpm dependent --it cannot be avoided.
Now if they could only get an electric water pump that can hold the pressure needed, give enough flow and not require a small power plant to do it then we will be good.
Of course you can choose to run Evans coolant and a pressure less system. An EWP will do great in that kind of set up.
If I keep guessing I am going to get something right--sooner or later
Last edited by olddragger; 07-21-2011 at 08:28 PM.
07-22-2011, 03:48 AM
#19
Super Moderator
Guys it an hypothesis, if yall read what i posted thats all I said. A lot of discoveries begin with an hypothesis after observations. I think my reasoning is logical, but it certainly is not proven.
You know Mazda doesnt change things without a reason. It does make you wonder why they changed this?
You know Mazda doesnt change things without a reason. It does make you wonder why they changed this?
07-22-2011, 07:23 AM
#20
I just wonder what if I underdriven Mazmart pumps ... have a feeling that will give me too little flow at lower RPM.
oh well.
07-22-2011, 09:56 AM
#23
For reference, comparison and for the fun of it, here are the 3 pumps in question. the S2 is a beautiful piece and is different from ours and the S1 in some elements of it's impeller. The key similarity to ours is what we refer to as a closed back design and tighter clearances.
The S1 is poor in many of it's features.
Paul.
The S1 is poor in many of it's features.
Paul.
07-22-2011, 10:39 AM
#25
Paul.