96WS6TRANSAM

I just wanted to see if anyone is running the electric waterpump and what your thoughts were on it im thinking on doing a turbo build with a power range between 800 and as close to 1000 horse as I can get depending on the thickness of the cylinder walls. So do you think the stock gear driven waterpump and gears can handle that or would I be better off going with the electric waterpump. The engine was hurt and made around 500 horse at the flywheel and lost oil pressure I didnt catch it in time. So I was thinking of a turbo build why its out and apart. Thanks for your input

Injuneer

An electric water pump flows a fixed rate all the time - outflows the stock system at idle/low RPM. The stock WP increases flow with RPM. You save a few HP at elevated RPM, because the engine has less coolant flow. The data I have from an SAE (Society of Automotive Engineers) paper on the LT1 cooling system innovations showed the stock pump outflows the electric pumps (including the high flow electric pumps) at elevated RPM. The guys that built my engine refused to even consider an electric pump, pointing out that my engine only runs between 5,000 - 7,000 RPM on it's trip down the 1/4-mile, and really needs a good coolant flow to handle the extreme heat generated by a 300-shot of nitrous.

Others will disagree.

bw_hunter

Actually, there is nothing to disagree with in Injuneer's response. Everything is quite true.

That said, I run an electric pump. I rarely drive at 5,000 rpm or higher and never reach 7,000 rpm. For my use as daily driver an electric pump keeps the engine cooler in traffic...and I live in sunny Florida. You'll have to look at your own situation and make your choice...is you car going to see a lot of strip/track time? Then stick with your mechanical pump. Is it a daily driver that spends most of the time below 4,000 rpm..then you can choose whichever you want.

Probably the biggest advantage of an electric pump is that you get to choose your own timing set instead of what GM offers...

This has been a topic that gets people pretty exercised but facts are facts...and Injuneer spelled them out....

Chimera96

the Meziere LT1 WP (HD) flows 50GPM. I don't know at what RPM a stock WP starts to flow more. If it is at 3000 RPM (just guessing) than from that RPM to whatever you are spinning your motor to under 1/4 mi conditions I don't think that in those few seconds....you will see any measureable decrease in engine temps using a mechanical WP.

I don't have any data on what a mechanical WP flows in GPM.

Regarding longevity, I have had a EWP on for 16 years and 85k+ miles. 100+ degree long desert drives, 100's of 1/4 mi runs, no problem. With that said I am making nowhere near the HP the OP is doing with his build.

Injuneer

When you tune an engine for a 300-shot, you don't want even a few degrees of extra heat, ready to cause detonation. I would think that a 1,000 HP turbo setup would present a similar concern.

I'll have to find the SAE paper.... it was issued back in 1992. I have my copy somewhere here in the house.

96WS6TRANSAM

Thanks for the input. If yours is making 800lb it should handle what i'm going to try to do. The all motor version peaked at 7000rpm and a 3800 stall ill just stick with my factory wp

Injuneer

A buddy of mine had a 30th Anniversary SS convertible, running 1,125HP at the flywheel, Vortech S/C 383. Stock water pump, stock fans. We both ran aftermarket aluminum radiators. His SS ran 9.05 @ 156MPH. Never had a problem with cooling on the street or on the track.

I've seen Auto-X drivers indicate they have no problems running with the electric fans. So as usual, there's two sides to every story.

slick1hunting

I had read something back when I was deciding to go electric or not about the flow ratings of the electrics being done with no load or resistance and was in agreement with better cooling at idle and very low rpm but no comparison at higher rpm. It claimed that in a closed pressurized system the reported flow numbers would be much lower. They also advised in race only type cars the stock system was a better choice.

bw_hunter

That was posted by a guy who used to frequent the board but doesn't come any longer. I don't know if it's true and he didn't provide any references. The race type engines reference was to the first water pumps that morose put it...little things that were made for drag only cars.

I guess I could monitor my engine temperature at various rpm to gather data if people want to see it...I run a meziere HD

Chimera96

yeah I remember that guy, he is a caprice owner in WI and used to rant about EWP's rated in non pressure vs mechanicals being under pressure for flow. he never provided a link or back-up to the source 411 he referenced. He also said they still draw power from the motor since the draw current from alternator....even though alternator is already putting out whatever amp capacity it is rated for.....the 7 amps a EWP draws is nothing to a 135 amp alternator

In any event, MANY track only or street big builds I see at the track have EWP's. The typical use was to have a WP that was not "mechanically" driven by motor so it did not suck any HP to drive it.

For me HP was never a reason....stock LT1 WP's did not last for me and pissed on Optis killing them. I switched to EWP when my warranty expired on my 96 (3 yrs). I never have replaced it since in the 16 years & 85k mi...YMMV

Since the EWP flow is constant vs a mechanical the later would surpass flow at "x" RPM. Under "sustained long term" RPM the mechanical will flow/cool more. Again in the few seconds we are talking about under 1/4 mi race conditions I don't feel that increase in flow over EWP would be measureable in temp increase.

7000 RPM....a stock mechanical....that is certainly a higher RPM than a mechanical pump and it's blade design was engineered for. Don't know at what RPM cavitation starts and efficiency drops...more to ad to the "what if" convo...

Injuneer

The alternator only puts out the rated amps if it has loads on it that draw those amps. Adding 7 amps to the alternator load increases the power required to turn the alternator via the serpentine belt. There is no "free" power.

The 1,125 HP SS ran at a peak of 8,000 RPM.

Kevin Blown 95 TA

7A @ 14V = 98 Watts which is about 1/7 hp. I'm not sure of the efficiencies of the different pumps, though.

As far as drag racing goes, when you are on the return road after a blast down the strip and the engine is still real hot, your engine is barely running, so the EWP has flow advantages there, since your mechanical would be running real slow just when you want some extra cooling. One other good thing about the EWP is that you can run it in the pits if you want, with the engine off. So if you rig up your fans with switches, you can turn them and EWP on and cool off the engine.

Injuneer

Remember, an alternator is not a 100% efficient device, and it is driven by a mechanical system the has inefficiencies. Then there is the question of under what conditions the 7A was measured. What delta pressure was assumed?

quickSS

This is a good point. I bought that SAE paper too and have no idea where it's at. BUT!!! I do remember a flow graph versus net positive suction head and they only took the stock LT1 engine and it's water pump up to 5500 rpm (thereabouts). Why not higher? ? ?
I know why. They stopped the test at zero Net Positive Suction Head at around 5500rpm. So no more extra flow above that rpm. It probably just churns up the water and cavitates a bit but still flows some coolant. The Electric pump on the other hand will continue to chug along and flow engine coolant and not get into a tizzy above 5500rpm.
One thing I know...the mechanical pump is so damn hard on the timing set. I always advise an Cloyes extreme timing set with new water pump drive sprocket when in a high rpm race application, (or the electric pump). I also realized later than sooner that the oil holes need to be there in the front of the motor to give an oil deluge to cool the timing set. Lots of oil! All builders have their opinion. I prefer my customers run an electric over a mechanical. The worry I have with the electric is unreliable wiring. (spend time making it reliable). The worry I have with mechanical is tearing up the timing set and water pump drive gear.
Karl Ellwein
Ellwein Engines
One of the sources for this John McGann LT1 6 page expose in Car Craft 2008
http://www.carcraft.com/techarticles...e/viewall.html

97WS6SCharged

It actually compounds the problem. Remember that nitrous will tend to have a cooling effect (sudden decompression of a pressurized gas) on the intake charge before it gets compressed in the cylinders. A blower or turbo is compressing air and heating it from the time it passes the impeller to the time it hits the combustion chamber. That's the reason we run intercoolers and usually some form of water/methanol injection.

That said, the only time I ever had a problem with my electric water pump was when I tried to jump a truck and for some reason I thought I could run the engine at a higher idle to make it go quicker. It didn't go quicker and I ended up burping coolant out of the over flow tank after about 4 minutes. I stopped carrying jumper cables after that.

IMO, just don't hot lap the car and it should be fine with an electric pump.