The Corvette in question is a 2001 Z51 coupe with a 6sp manual. The drivetrain is stock with exception of Corsa Exhaust, X-pipe and headers. For years I've watched the Corvette become slightly less and less tolerant to summer heat a little tiny bit each year. This year since I'm getting the itch for engine mods I installed a DeWitts radiator and new thermostat.

Now everything is running nice and cool and I have no complaints but I do have a question. I've noticed at lower engine speeds (in 6th gear - ~1400 rpm) but maintaining 55 mph the coolant temperature will creep up 5-9 degrees F. If I drive drive in 5th gear or even better 4th gear at 55 mph with engine speeds closer to 2000 rpm the coolant temperatures will be lower right at advertised thermostat temperature. (Outside air temp around 80 degrees)

None of this is a huge deal as it's no-where close to a high temperature and I'm totally being picky but I was wondering if the water pumps in our car had a sweet spot or even if I might need to consider replacing my water pump due to age. For reference my Vette only has 50,000 miles so it's a young pup in that regard.

Thanks

 

Like any mechanical pump, the water pump will push more water at higher rpm's, the higher flow rates cause increased cooling.

 

That was my theory but I wasn't sure if there were any known strengths or weakness' to the LS1 pumps. I've never noticed this behavior on any of my other verticals. As I'm aware this 100% picky, I'm mostly just curious.

 

Are you running an underdrive pulley/balancer?

 

No, I have the stock pulley and balancer.

 

If you're able to maintain acceptable water temps at cruising speed then you're good. If you start seeing high temps like 220 while cruising, your rad is probably plugged with sand and road crap. Mine usually cruises around 200 but one spring as it started to warm up suddenly i was seeing 220 easily. Before that I'd only see 220 in traffic on a HOT summer day. I cleaned a TON of sand and pinestraw and road crap out of my rad and went right back down to 200.

 

Yeah, I know I'm good from the stand point of the temperature level. I figure most would be flat out excited to run at the 198 degees F I'm seeing at cruising and 190 degrees F when I'm driving it harder. It just find it interesting that I've always assumed in the past that if I was running warmer than I wanted I would try to get it in the highest gear possible for the lowest rpms and maintain a speed over 45 mph and the temp would drop. What I'm seeing with the new DeWitt's radiator which is "over-kill" for most street driving is the water pump appears to be the next weak link. Plus the conventional thought I had about just driving lightly at higher speeds is not correct.

I know I have no danger in damage to the engine I'm mostly just trying to understand if anyone else has seen this condition as well.

 

You might have 99 problems but cooling isn't one of them, lol. Try running at 70 mph in sixth and report the temps....55 mph in 6th is probably close to lugging the motor in the sense that it is not really in its powerband and less efficient, A/C might be on, etc.

 

This.

 

TrackAire, well said... Around me are tighter curvy roads in the hills so cruising at 70 doesn't happen all that often. I typically work between 30 and 90 mph but never steady speeds. The noted 6th gear and 55 mph was on the way to work on a two lane hwy.

I'll need to wait for a longer road trip to investigate the 70 mph steady cruising, thanks for writing.

Armchair, I'm sure this is the case. Just more noticeable than I expected to be honest.