BaronVonBigmeat

If I had access to a laser cutter or waterjet, I would love to try building a bladeless water pump.

In Issue #18, they described a NASCAR team which had modified their water pump by replacing the impeller with a disc pack, to get the same flow but with less parasitic loss. I think they picked up either 5 or 8 HP IIRC; granted that's a NASCAR motor, but on the other hand the design was cobbled together and not really optimized. Also they are extremely durable, and have little (if any?) troubles with cavitation.

globi

There's no mechanical water pump conspiracy.
Fact is that if an electric water pump fails one is in deep ****. It's not the same as an electric fan, that doesn't even have to run constantly. Fact is also that no one notices 1% more power, so why take that risk and add a few more pounds at the same time.

Nevertheless electric water pumps will eventually displace mechanical pumps. Otherwise car industry suppliers like Siemensvdo wouldn't sell them.

If there's a conspiracy then it is the toilet brush conspiracy. Why are there anti stick pans but no anti stick toilets? Clearly, the Toilet-Brush-Mafia doesn't want any of this.

olddragger

iTrader: (3)

Baron-
Thats a good idea--Summitt racing sells those types of disc's for american v/8's.
globi-- mechanical pumps also fail. belts also break etc. both systems are not prefect but i think that a high quality electrical system installed properly would be just as reliable as the mechanical.
To me the advantages of the Elect pump are
1- increased cooling power at lower rpms--ie city driving ,congested driving in the hot summer's. this would help with getting longer engine life and less heat damage on things that are under the hood (belts, hoses,electrical stuff etc)
2-it could be programed to circulate the coolant for a time even after the engine is turned off. (fans also).
3- there has to be an increase in available h/p -- amount--to be seen.
4- less labor to replace/repair(once installed and functioning)
5- can be mounted anywhere
6- no more cavitation issues
7- would look really cool!(no pun intended)

Heck we already have electrical power steering!

Some thoughts on disadvantages-
1----newest of the system(but hey isnt that one of the things rotary lovers like!? The challange of doing things in a new and better way!?)
2- lack of variety of systems available.
3- unknown needed flow rates (although if it works for a nascar engine it should be ok for the rotary?)
4- may be better with a 24 volt system--unk at present(most elect systems I have seen are req 5-7 amps and we have that available now)
5- lack of pcm control (so it would have to be a stand alone control---maybe not a bad thing)

At present I am installing a fence for our dog's(wife is getting chemo(good prognosis-no worries there) and they need to get out of the house) so as soon as time allows between that and the soccor o rama schecule my daughters have I will get my gauges installed so I can get a baseline for my car temps and I may cont to pursue this as able. I think it is a good idea and maybe even Mazda will listen.
Keep it going guys- i dont have to be the 1st to install.
olddragger

r0tor

iTrader: (1)

it also sounds like a bag of popcorn popping and some noticeable vibrations if you truely experience it...

r0tor

iTrader: (1)

did you ever think they run a large pulley to reduce parasitic losses and they can do this because its a race engine and they are not concerned about what happens when they slow the pump down and have a car stuck in traffic on a hot day for an hour with reduced flow?

Spin9k

Interesting story about doing the water pump conversion on a Chevy engine. The best part is the carefully documented testing showing gains at all RPMs vs over & underpullies vs electric pump.

http://superchevy.com/technical/engi...s/0408sc_pump/

Spin9k

Here's another w/dyno chart. from these two conversions they are getting somewhere in the area of ~10HP at 5-6K which bodes well for us getting somewhat more esp at 7-9K as this quote testifies to this. Also a consistant increase under the curve all the way up.

full story http://www.projecttransam.com/projects9.asp

olddragger

iTrader: (3)

Good article --thanks.
olddragger

TeamRX8

iTrader: (25)

as usual somebody makes an exagerated generality that will not likely apply. It all depends on what the flow, pump size, and impeller design is from the factory. To take the results from a V8 application and then make gross assumptions about what you'll get on a Renesis rotary application is not very intelligent ...

RotaryManiac

10 extra torque would be nice.

Spin9k

As I have come to learn here TeamRX8 you often make sarcastic remarks that are not called for about seemingly innocuous comments people post. Although I respect you for the information you regularly supply, your ability to incite often exceeds you ability to inform.

IMO a reasonable person reading this thread would realize that it all depends on what the flow, pump size, and impeller design is from the factory. As no one knows the answer yet for the rotary engine, mere suggestions about results we might get extrapolated from others projects do not equate to an "exagerated (sic) generality" nor "gross assumptions about what you'll get on a Renesis rotary application".

Finding and relating information about empirical results others have obtained and supplying it to all of us here simply makes sense if one is trying to evaluate the purported benefits that this modification might provide the RX-8 community IMO.

Please take note, my intelligence is very much intact, thank you, and does not require critiquing from you. Furthermore I would offer a suggestion that you would get a lot further in this world with milk not vinegar in verbally dealing with others.

Have a Good Friday and a nice Easter weekend.

globi

It at least appears, that the waterflow through a rotary engine is less restrictive than through a piston engine with its rather jagged cooling space. If it is less restrictive the water pump would also need less power.

If you look at that picture, the water basically flows through a relatively short block (big area and short distance as opposed to small area and long distance).
http://www.der-wankelmotor.de/Motore...a_renesis.html

HeavyMetal699

A few years ago i asked my mechanic the same question, but in regards to a mustang. He told me that there will not be a noticable difference if any at all in performance, and that mechanical water pumps are much more durable than electric water pumps. From what i understand for a MUSTANG there is absolutely no benefit except spending alot of money. On a high RPM motor where cavitation can occur i can see the real life benefit of having better flow at both upper and lower rpms, but as others have said I doubt there will be any difference in performance. I would suspect that underdriving the water pump would be a good indication of any possible performance increases you might have. Whoever attempts this modification i hope they size the pump right for the Renesis.

Just as a reference the mechanic im referring to is slater from slaters mustangs in houston. Maybe some houstonians will recognize the name as he builds some of the faster mustangs and F-bodies in the area.

olddragger

iTrader: (3)

heres one dyno results of a v/8 install--- well dang dont know how to insert it here but the net address is www.ws6.com/mod-14.htm.
shows 6 hp gain on a trans am. On a dyno jet, independant test.
read for yourself. It just makes sense to me.
Also on durability--new cars are already coming out with the electric water pump--i think a good quality system and a good install would be just as durable.
If you asked your guy a few years ago--then a lot of things can change in a few years. not knocking you man--appreciate your input. and you are right some study would be required to choose the right size/flow rate pump.
olddragger

Spin9k

One thing all these dynos show is that power loss increases with rpm. All these dynos stop ~6000rpm. So however much HP our pump uses, the advantage would be to those using the upper ranges regularly & for long duration - like doing track days. I normally spend a good part of the track session between 6-9K rpm. "Normal driving" benefits may be quite small vs. cost, but I'd love to see a high rev engine dyno comparison w/one of these electric pumps.

BaronVonBigmeat

Of course, our water pumps probably have a larger pulley than a similar pump on a piston engine, to slow the pump down. It would be interesting to find out for sure though.,

globi

Before investing in any electric water pump projects:
I would buy just this $40 pump to pump water through the engine http://www.northerntool.com/webapp/w...6970_7738_7738
and dyno the car without the belt (or belt on the water pump) and see whether I indeed get as many HPs as some of the Camaro and Mustang guys seem to find.

TeamRX8

iTrader: (25)

you might want to start by figuring out how much the pump flows

scratch that, you might want to start by learning about pumps in general first ...

globi

In order to measure the difference with or without water pump on the dyno, you just need a pump that pumps something - just to make sure that it won't overheat during these few seconds.

olddragger

iTrader: (3)

good idea Globi, but dont forget there are other advantages to the elect pump over the mechanical.
1- better coolant flow in congested city traffic where your speed is low and air flow is lower.
2- can continue to circulate the coolant after the car has been turned off for a determined period of time. Much better cool down.
3- no more cavitation issues
just to name a few(and if we could GET more than 6hp with good reliable cooling I bet people would take notice!)
olddragger

r0tor

iTrader: (1)

umm, instead just disconnect the pump pully and replace the radiator hose with a hose froma a city water source and crank it up fulll force... actually did this in a college dyno lab once and it works pretty well

Spin9k

Here's an interesting graphic from the parts manual. It shows the pully sizing and the pump pully is smaller than the crankshaft pully... meaning if the crank is turning at 9000 rpm, the water pump is turning even faster, a rough measurement gives about 11,250 rpms.

So one of three things are in play here, either we need high rpms to provide enough cooling at max crank rpms given the pump design, or we need to have the pump geared up to provide sufficient low rpm cooling, or both. Either way, one could guess that at one point or another in it's speed range, the pump is out of its best perfromance envelope for the needs of the car.

dsmdriver

iTrader: (3)

Cavitation is only an issue for the road racers here. Cavitaion won't make any difference to you on the street, since you can't stay anywhere near WOT at high RPM for more than a few seconds. This is assuming that the pump cavitates at all, which we have no real proof of yet. It is possible to design a pump that works at 750 RPM and doesn't cavitate at 9000 RPM, so for all we know, cavitation doesn't happen.

Electric water pumps are nice, but a lot of their benefits come from managing the pump correctly. You want it off when the engine is cool, on full bore when needed at idle, using minimal power when needed as the engine is producing power, and running after the engine is off. This management isn't hard, but just throwing an electric pump in and hooking it to the key won't give you all of that.

olddragger

iTrader: (3)

Absoulutely dsmdriver, more to this than meets the eye, but as you also said it is do able.
It is going to take a while for ANYONE to get this done, presently no one that I know off makes an adaptor kit for the Renesis. There is one for the 13 B(i believe it was the 13B).
I would like to get this going but 1st my groundwork will take a while--wheres Charles Hill?
hey Charles you there?
Olddragger

globi

'Ever heard that you shouldn't push the engine when cold? Unless you pre-heat your city water this is definitely not recommendable.