LT1 POWR

iTrader: (4)

Motor is a TC78 383 with about 9.2 compression making a little over 600 to the wheels. Cooling system is a Griffin LT1 replacement radiator rated to 600hp, meizer hd water pump, 160º thermostat, flex-a-lite 420 puller fans and 50/50 mix antifreeze. Also pretty sure there isn't any air in the system. While cruising it runs at 190-210º, at wot about 215º, but at idle with fans running on high it gets to 240º+ before I shut it down to run the EWP and fans to cool it down. I don't think idle AFR is too lean or anything, and timing is around 16-22º. Fans are set to come on at around 190º so I don't know why its running so hot.

LT1

iTrader: (1)

On factory tune the high speed fan should go on at 235 degree's and turn off at 230 degree's.

I would pressure test the cooling system and check your radiator cap also the thermostat to make sure its all working correctly.

jaycenk

iTrader: (1)

are you using a factory steam pipe on the back of the heads? Did you make sure the pipe was clear of clogs?

LT1 POWR

iTrader: (4)

Yup, factory steam pipe, not clogs. So 230ish isn't too hot for these motors then? I know my 6.5TD can go up to 250º, but I keep it below 215º. With a 160º thermostat and the fans set to come on at 190º, it shouldn't be getting past 215º or so.

LT1 POWR

iTrader: (4)

Just called flex-a-lite to confirm I have 420 puller fans and they confirmed that I have 440 pusher fans, so I'll swap out the blades for the correct ones and hopefully that'll fix it. I love it when you order something but get the complete opposite although it has the correct part number on the box.

How many people are running without thermostats on higher hp motors? I no longer have HVAC in the car, so running cool won't be a problem.

GMRACER13

iTrader: (1)

16-22 degrees of timing at idle? There is your problem. You have a low compression motor with "slow burn heads", no need to run such little timing. I run ~35 degrees with 12:1 compression. Advance your timing and see what happens.

LT1 POWR

iTrader: (4)

I'll let my dyno tuner know. Originally we had to drop the timing down to get the idle down, but now that all the vacuum leaks are fixed I might have to up it a little. That'll probably solve my hesitation off idle problem too. Anything I can do to get underhood temps down is good. What kind of temps should I be seeing with a temp gun while pointing at the headers?

jaycenk

iTrader: (1)

That kind of **** drives me nuts. Especially when I inspect the parts before I start and miss the mistake as well. I've gotten Wrong part right box and right part number so many times. I've even inspected them and convinced my self it was correct even though I knew initially it wasn't lol. Nothing worse then getting half way through a project and knowing that you have to stop and wait days to get the right part.

Puck

iTrader: (17)

Keep in mind that you are also well past the radiators rating, since radiators are rated at flywheel horsepower. Your idle temps will never be as low as on a stock LT1.

More powerful fans will help dissipate heat at idle better, and getting your blades correct will be a great start.

Funny story, a few years ago a guy had a similar problem and ended up finding a plastic bag flattened over the front of his radiator.

jaycenk

iTrader: (1)

That happens to me at least 3 times a year. I always watch to see if the bags I run over come out the back now lol.

shbox

I always do that too!

ikaros23

same to me my car overheated once like a **** and boila a plastic bag over the radiator lol

LT1 POWR

iTrader: (4)

Just to make sure on the stock fan wiring, the black is ground and the other is power, right. Got the new blades today and want to make sure everything is good before I fire it up.