This was a discussion from the RR forum, moved it here for more visibility and because it fits this forum better...

http://www.corvette-guru.com/modules/ ... hp?topic_id=5201&forum=55

Synopsis:

Car runs hot (~230*F with peaks over 240*)
Dyno pull showed an A/F ratio of 14.5 - 15. Previous pull had A/F at 13.2, only changes were 52 mm TB back to stock 48 mm. Changed fuel filter and TB back to 52 mm and A/F went back to a manageable range.

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Yup, DeWitt's radiator with an EOC and a Hi-flow Meziere electric WP. I run straight water (with a bottle of water wetter), and I just put on a 24 psi radiator cap but didn't see much difference. Temps run a steady 230*, they were hitting over 240* Thursday.

For the oil I have the EOC in the radiator in series with a bigger external cooler in front of the radiator. My oil temps were really high when I first put in the 383, but now they're well under control.


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How can the TPS trick the engine into running lean? I changed the sensor from one TB to the other, it easily could have been leaking or mounted improperly (if that's possible).

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I've got one as well, but I may got back to a mechanical for road courses. The reason being the HD EWP puts out a constant 55gpm which is great for drag racing and autoxing, but a mechanical pump puts out 110gpm at speed.

I've been told 240 water temp at the track is normal, but I dont' like it.

If the TPS sensor is not mounted right, it would give the computer a wrong reading, so the engine my think its getting more air than it is.

BTW I started a thread "other there"

http://forums.corvetteforum.com/showthread.php?t=2134515

Check this out:
[QUOTE]Vector Vette:
Brian,
We could get the L98 motors to run below 200 on water but never could get the LT1 to do that. 240 is too high though. I ran my C4 with a Meziere electric water pump, Griffin radiator, heat extractor hood, take the guts out of the thermostat, block off the bypass for the quick warmup, water with just a little anti-freeze for corrosion protection. I had my rev-limiter set at 7200. With this setup the car would run between 210 and 220 water.[/QUOTE]

More info:
[QUOTE]Vector Vette:
Mark,
The water pump is not a problem. I ran it on my SCCA racecar for years. It is a 383 LT4 with 465 rwhp.[/QUOTE]

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Hmmm...if it thinks it's getting more air than it is, isn't that going to cause the ECM to richen the mixture?

It should, but if it's getting more air that the engine knows, it will lean out.

Yours isn't a MAF car right?
(what year is car come to think of it)

w/o a MAF it needs the TPS

Safe to check everything though.

What's you codes? How are you 02 sensors etc.

This came up on the RR thread:

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I wish that table would go up to 7k

Still very enlightening.

~40 for each bank or ~80gpm overall.

Attached is a graph of the data, with extrapolation below 2000 rpm and above 5000 rpm.

The data from 2000 - 5000 is absolutely linear and extrapolates to zero -- indicating that there are no losses over that RPM range related to RPM.

My guess is that the water pump does not lose efficiency above 5000 -- it would take a lot more than 7000 rpm for the thing to cavitate and lose efficiency, but don't have the characteristics available to determine that.

By the way, the higher values are:

RPM GPM
6000 - 88.8
7000 - 103.7

Attach file:

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  water pump flow - from edelbrock.jpg (0.00 KB)

Well I'm impressed.

a couple of thoughts.

If the coolant is going too fast, it will not have the time to transfer heat. That in it's own right might create the perception that the temperatures are lower than they actually are. Does this make sense???

Or, the coolant is running too fast and doesn't spend enough time in the radiator to allow it to do its job?

I assume you are running a t-stat? The restriction is part of it's benefit - slowing down the flow so it actually sticks around long enough to draw off the heat.

This is a reach, but, when I had my heater core bypassed, the engine had a tendency to run hotter. I think that was 2 fold, with one additional conflict: 1) the engine lost some coolant volume and 2) the AC fan wasn't on as much versus 3) the heater core helped that much as a radiator, cause gee, it's itty-bitty. Hence, I lean towards #2.

Which leads me to ask, I didn't see reference to fans... stock? SPAL? Something else?

Second thought... cavitation. I don't know what the SBC does, but the LSx does have a problem with that. My neighbour is a desert racer and earlier in the year, before the truck flamed out, they had a class-A truck with an LS7. The waterpump cavitated at about 7k RPM. It is obvious that the Corvette C6.r uses an external waterpump, versus in block, so the problem is resolved. Is there any way an external waterpump can be fitted to the LTx? Is there space for one? I know it's a huge reason for not having a dry sump oiling system, but I am not well versed enough in what pure racing components are adaptable.

I am also wondering if aero is hurting you... do you still have the intake spoilers? If not, the air may just be passing you by... The big mouth may help here. Also, the heat extractors on the hood may also help. Give some of that hot air a place to exhaust. I just don't know how the SCCA would view some of those mods. I guess the way to answer this is simple, if you pace the track at normal highway speeds, say, 80mph, does it run hot? If not, then perhaps aero is something that needs to be reviewed.

So sorry your having this kind of event... that sucks.

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LOL

we need to do a thread merge!

That can be arranged.