Anyone know of a LS3 Camaro style high flow water pumps? I have a new AC delco LS3 waterpump on my 5.3 swap with a 160 tstat and the heater core ports are plugged. Car runs great 175-185 most of the time but will creep up at idle to the high 190s, alittle throttle even not moving and temps drop 5*F instantly. I have a feeling the idle flow is low. Flowkooler doesn't make an LS3 style pump and I'm not seeming much out which is odd.

 

I would think the thermostat would be slowing the flow more at idle than the water pump.

 

too much flow is just as bad as too little flow.

 

I dont think thats the case. On my other LS1 turbo car i have a flowkooler pump with a 160 stat and that car runs cooler than this one. 30% more flow so I don't think the tstat is much of a restriction at all.

 

Thats not even remotely true.

 

​​​​​​​The myth that JUST WON'T DIE.

 

Right up there with high volume oil pumps sucking the pan dry....

 

No one has any LS3 camaro style high flow options?

 

Is it possible you might need more air movement at idle?
What's your current fan setup? Engine driven or electric?
If engine driven, you might need a better shroud and/or more efficient fan.

 

electric fan. Spal 16” brushless with molded Dewitt’s shroud, 100% core coverage and I measured fan CFM at 3500 actual on the car. Radiator is brand new high end aluminum dual 1” core USA made. I know it’s not airflow as if I don’t move the car and just give it throttle the car cools immediately and doesn’t climb.

 

OK. Just making sure the bases are covered. And I screwed up. I now remember you're discussing electric fans in another section of this forum. DOH!! LOL!

 

What's you idle speed? Does it have an underdrive crank pulley?

 

650rpm and stock crank pulley and a Lingenfelter 160 Tstat for the LS3 pump (its different than the LS1). I'm also running about 30% antifreeze as I try to keep it to -10*F on the freeze point. Drove the car in today on a cooler day (high 50s) while driving 179*f-183*F running temp on the holley handheld doesn't matter the speed. Idle it will climb up to the 193-198*F at alight, as soon as i touch the throttle (even when sitting still at the light) 1100-1200rpms the temps drop quick to 183*F ish. I don't even have the spal 16" fan programed to be full speed till like 205*F I would say the fan is running at 60-75% at the 195*F mark. I could be running 5-10mph and have rpms up at 1500 and it doesnt go above 183*F, give it the beans on a pull and 183*F temps don't even try to go up. I feel like its a lack of flow at idle to maintain the temp. Its not really a "issue" as I haven't had to idle long enough to get temps above 200*F but I'd rather not find out in a traffic jam or something.

I'm just shocked that their are no real LS3 aftermarket options for high flow pumps. I would do another flowkooler LS1 but I had to remove the LS1 high flow (cheap version) as that top area above the outlet was contacting the throttle linkage I made for the 700r4 TV cable. I actually sanded and polished it down to clear but the LS3 pump just fits so much better and offers lot of clearance as the pump outlet is on the driver side. I guess I'm also kinda shocked the stock LS3 pump doesn't have the flow at idle. The ls3 pump has a press in stainless plate on the back, if it was the bolt in with the Oring I would have tried to weld a plate on the back like they do with the LS1s to increase flow. I don't want to mess the plate getting it off or not be able to seal it back up good.

 

Would it go above 193-198 degrees if idled longer, or does it stabilize at that level?
If it stabilizes at those temps there is nothing to worry about. These engines stock run at 200 degrees all day in some applications with a 187 stat.

 

I haven't had the opportunity to let it. I did let it idle for like 20min and warm up and it never really got above that. I'm not sure how long I would just let it sit and idle. I think its interesting for it to go up 10* or more over a 1-3min period tho sitting at a light.

I wouldn't be worried at 200*F either but given that it can cool at 183*F it bothers me that the waterpump can't flow enough at 650rpm but can at 1100rpms.

 

Looks to me like a borderline situation. Your setup just doesn't cool quite enough at idle. Try once and see where it goes for a longer time idling. Watch the temp while it goes for a loner time than before. If it approaches 250 give it some gas to cool it a bit.
Maybe raise your idle to 750 and see if that fixes it. 750 isn't that high an idle.

 

I agree with Customblackbird. My bone stock LM7 motor with two electric fans, a great big Cold Case radiator, a 195 F thermostat and a 650 RPM idle engine also seems to be a little water pump flow constrained at idle. This is not to say that my engine overheats - it might creep up to 215F on a hot day stuck in traffic. But stuck in traffic, idling in neutral, I can bump up the engine RPM with my foot from 650 to about 1000 RPM and lose 15 degrees in just a few minutes.

The only way that I see this temperature change is using my Dakota Digital temperature gauge - not the needle - but the digital integer readout. GM temperature gauges have way, way too much stiff, needle hysteresis around the middle of their operating range to ever express a temperature change like this. The DD digital readout gauge seems to have very little hysteresis and tracks these changes very quickly.

And yes, I also have a Flowkooler part number 1669 LS truck style of water pump that does help a little. However, the extra 350 RPM helps even more.

Rick

 

I wonder if there is a way to over spin the waterpump without going crazy with the idle. The 650 is perfect at the moment, got the IAC dialed in and everything. I'm not aware of an pump pulley swap or a larger crank pulley. I'm temped to get a ebay special $80 and open it up and see what can be done.

 

I actually wouldn't worry about it. It will heat up some while idling, but I'm betting not much more even after extended idling. And even at that, you're not sitting at a red light more than a few minutes. You sit, it goes up about 20 degrees, the light changes to green, and you cool off. The engine too....

 

Have you tried bumping up the idle speed some? Even to 700 and see if it makes a difference?