I don't think the logic is whack . It depends on what you want . If (like me) you live in a climate where the A/C is only useful for a couple of months but nice to have the rest of the time you are not going to notice a great dropoff in AC efficiency with underdrive. You may well notice some xtra hp in the low/midrange however which is when you might have the AC on (ie not when racing) . Also - the xtra hp comes from underdriving the AC+water pump+alternator + any gain from weight reduction .Not just the AC.
Same argument applies for the water pump - this car was designed to run any any climate so underdriving the wp in a temperate climate should not create any issues. Especially if you fit this kit - you should get back any cooling you lost.

However if you want really good AC + the extra HP - these two mods may compliment eachother well . Anyway - its just a theory & if anyone has both mods they may be able to tell me if it is BS.

Edit : i guess you have to consider the extra power needed to drive the alternator to keep the fans running & whether the underdriven alternator will be able to keep up - hmmmmm too much thinking

 

underdrive helps when the water pump is cavatating--look at all the 8's on the track--think of why they all have really significant underdrives on(much more than the 15% for the street). Our water pump impellar is crap.
olddragger

 

Based on anecdotal evidence, I presume?
It is the same water pump impeller design that was on the '7 (and the 626, Millenia, MX-3, MX-6 and 929).
Someone is going to have to show an actual reduction in water flow at high RPMs to prove that one. So far, all I have seen is increasing temps at higher RPMs shown as evidence and that is BS.

There are no measurable gains from UD pulleys on this application under any circumstance.



Look! Another page-topper.

 

I hope you are wrong on that - just got mine & plan to do some tests to see if there is any measurable gain.

 

interesting ? has anyone looked at the difference between the pumps...

if getting a photo is needed.... i can pull the one of the motor on the floor..

beers

 

That would be me. I'm really not too sure how it could lower the pressure. That doesn't make sense to me.

Also, the way I installed it, its in series with the stock coolers. Therefore, no oil flows until the stock oil cooler thermostat opens. So, there's no way its causing the oil to reach operating temps more slowly.

Thirdly, there really can be no way that a cooler that fits in the same place as the stockers can be that much more efficient. The only real gains to be had are by 1) adding surface area, or 2) increasing the airflow over the surface are you have. If it fits in the same location, its got to have about the same volume as the stockers and hence, about the same surface area. The only gains to be had in the oil cooling department are through fans, or through a third cooler.

 

it was you...

shear volume would help.... but did you ever run temps on it before and after???

yes i know search...

beers

 

No. Wish I had, though. I figured I was putting more heat in with the turbo, so I'd better take some out, too.

 

sorry,
of topic, but the oil cooler thread is a great idea...

this is a photo i posted on the otherside....

beers

 

and the screen reads as.



afr timing mph




maf intake temp cat temp




ltft h20 temp fuel level



below the touch screen. the outside temp is 86 deg....

this is at 6k rpm to get the temp up...

beers

 

And the point of the above illustration would be? (Those are all nominal levels, except the air intake temp that is a bit high for the ambient at that speed.)

 

no MM not based on ancedotol evidence. i had a long conversation with the tech director of ROAR racing, he explained to me what they have had to do in regard to the water pumps to get their temps down. They have blown several engines due to high temps,And before you say this was just for racing , high rpm needs, he also explained that they did this to their daily use 8's also that also see occasional track days(basically stock cars). Temps are temps whether you see them on the track or in stop and go traffic in high ambeint temp days or in heat soak situations. He was very critical of the impellar(sic) said it was one of the worse he had seen. Starts cavitation at around 6K. Modified it as they have to use the stock water pump.
Mad Dog that was a good mod you did. I remember how you said that the stock coolers were much more inefficant(sic) than the one you bought because how cool they were to the touch vs the 3nd one. There are much better coolers available now that fit in the stock locations. It is all about air flow as you have said and you should see the fins(stainless steel not aluminum!) and the space inbetween them! With the stock ones and the aluminum fins , some get bent and further block the flow. AIr flow is 100% better with their coolers. At the time you did your mod I dont think there was another option. I am surprised that your oil warm up times remain the same with 3 coolers vs 2
UD does help with cavitation and it does free up some power.
study after study has shown that MM.
High rpm really drives the temps(coolant and oil) it is also one of the (high rpm) great things about the rotory. We just need coolant/lube systems that match the need of the engine. And we are getting there.
olddragger

 

Once again, I 'll believe it when I see actual flow data and temp differential numbers.
BTW, why are you intentionally mis-spelling things?


Stainless steel is a HORRIBLE choice for an oil cooler! It retains way too much heat. Copper wuold be a good choice.


Dyno after dyno shows it does not. I'd love to see your studies. I'm sure these "studies" are authored by the manufacturers of the pullies.

 

Look out! MM is on a rampage today

 

Nope not intentionally misspelling--i just dont speel well.
Go to the viability of the EWP thread and look at the chevy dyno that used UD pulleys, the EWP and OE pullies for one. Independant test. Find some more if you want. I have seen a good bit and I have the agency pulley on my car and I have felt the differance and seen the differance on the temps.
Dont take my word for the cavitation( i dont have spell check--I think I need it ask others also.
The fins were stainless according to Chris as there were a lot of trouble with the fins getting bent inward cutting off the air flow. I dont thinks the entire cooler was stainless though as you are right about the heat conductivity
Let me add something else to get doubted. Probaly most of us are running oil cooler and a/c protection screens. How much blockage of air flow do you think that is causing?
If interested here is a crude test. Take a screen out, get a good fan. Cut a strip of paper approx 1/2 inch wide and 2 inches long, Iused an old evelope, hold it agaisnt your screen with your thumb --whatever. hold the screen and the paper on the fan (on high)--look at the piece of paper(i looked from the side) and notice how high the fan is blowing it. Now while holding the piece of paper still slowly remove the screen so the the paper remains in the same place but the screen is gone. Does the paper get blown higher or not? You bet it does. I estimate 30-40% higher. Take that for what it is worth.
I took mine off.
olddragger

 

I wondered about how much air flow they cut down.

The Mazdaspeed bumper grilles must cut down on air flow too then.

Not as much since they are not directly on the coolers though.

 

Then why did you put a [sic] after each word you mis-spelled?

What does a Chevy dyno have to do with the RX-8?
Once again, the butt is not a dyno and concensus is not science.

That is what a fin comb is for. If you are getting a lot of bent fins, use a grille.


Not a good test.

 

i would not think that 190 was a nominal level as it would have been about 198 before..... as to the intake temp yes it is high as i took the time to heat soak the motor before the run...

intake air temp usually runs about 10 deg over amb temp at a 60 + cruise.

beers

 

even with the RB duct in place ?

 

Hmm, I don't start moving into near-200° range until ambient gets well above 90°.

 

What did I ever do to you? Jesus. You need a hug or something?

Sic is what is used when you dont think you have spelled the word correctly.I did that just for you.

One day you are going to realize that parasidic drain on an engine----- is not engine specific. A mechanical water pump on any engine uses power. It takes more power to spin it faster. It takes less power to spin it slower. Everything else being equal. You really dont understand that?

Kind of hard to use a fin comb in the middle of a race I guess.

Didnt say it was a good test--I said it was a crude test. I thought you would understand that word.
Good night all--you too Maniac
Olddragger

 

yes,

if i get about 80 mph, the intake temp gets down to 8 deg over outside temp.

this is after a heat soak... if i just drive the car away cold and go cruise it takes a while go get the intake temp. up.

but the norm for my car is 10 deg above outside temp..

stop and go traffic. about at least 30 deg warmer.

beers

 

might have something to do with my special problem.

beers

 

A 2 hr drive to Atlanta on a 96-97 degree day at 70-80Mph with or with out the A/C on gives me coolant temps of 185-190 F and oil temps at 190F. Oil temp will go up 10 degrees or so if I do a fair amount of acceleration to pass. Load . of course gives you higher temps.
OD

 

holy carp guys....anyone else have any results with this mod?