eb02z06

iTrader: (18)

I'm not sure if anyone else has noticed this but the last 3 cars that I modded with AFR heads and a underdrive pulley all had cooling issues. All them got hot when they sat and idled in the heat. All had 160 stats, and the fans programmed to match-it didn't matter if the idle rpm was 800 or 1000, same thing at idle the temp climbed over 200. This was on a 02 Z06, A 02 Vert and C6 A6. Swpped thermo's, purged the system for air using the a Snap-on tool, head gaskets installed properly but at idle the temps climbed over 200. As soon as you drive away the temps dropped. Every owner noticed this immediately as they already had a 160 stat and the fans programmed before the head swap. Could this be just the way the AFR castings are designed since they have alot more meat? For the extra 5-8 rwhp a pulley provides it doesn't seem worth it-has anyone else noticed this or am I just overlooking something?

Thanks!

SOMbitch

iTrader: (8)

I have a 98 T/A (temp guage works, not a dummy guage like later ones) and mine climbs to 210 until the fans are commanded on and my temp immediately drops back down. I take it you mean the temp rises with the fans on. Hmmm.... Subscibing.... I was strongly considering AFR's while I'm saving and I already have a March underdrive in my living room.

ArKay99

iTrader: (1)

I've had AFR's on my 99 C5 for a while. I haven't had this problem and even went to a 180 degree stat because the car idled and ran better. One thing it might be is the AFR's have more mass than a stock head so they may retain more heat.

vettenuts

iTrader: (4)

I don't have much under drive (10%) and haven't had problems with either stock or Dart heads. I may go to a 180 on my new setup, which will include AFR heads. One thing I have been curious about is the ability of the stock water pump and after market pumps like the Evans or soon to be introduced Edlebrock. I am trying to figure out if the additional flow would provide worthwhile benefits with regards to keeping things cools, especially the rear cylinders that are getting the heat loaded coolant from the front cylinders prior to the coolant making a turn (if I understand the cooling path of the block/heads correctly). With an underdrive pulley you may get some cooling benefit from an electric water pump.

moeZ28

iTrader: (7)

I believe it was the 2000 model year and later cars have a dummy temp gauge that only shows an overheating situation. other than that, they stay primarily at the same temp on the gauge anyway.

SOMbitch

iTrader: (8)

Mine goes up and down in stop and go traffic. It is actually pretty accurate. They changed to the dummy guage in 99. One of the only advantages of a 98.

vettenuts

iTrader: (4)

The other thing to consider is that with AFR or any other aftermarket head, your cylinder pressures are likely higher and you are dumping more heat as a result.

Tony Mamo @ AFR

iTrader: (13)

I have ran them in my 346 (the 205's) and my 383 (the 225's I own currently)....my temps are perfect and cool as a cucumber. I run an underdrive and an EWP (Mezeirre). We have shipped literally thousands of heads since our launch of the product in 04' and no one seems to have any cooling gremlins whatsoever....alot of our customers road race with them as well which is much more taxing on keeping temps cool.

Not sure what issues you are having but based on the numbers, it seems highly unlikely it's related to the cylinder heads.

Feel free to give me a ring at AFR....maybe we can figure something out either way

Tony

eamador11

never heard of that. i have AFRs and ASP pulley. I can sit in traffic and the idle forever and the temps only go to 185deg. in the summer, ill see it hit 192deg. in a heat wave, it can hit 213deg.

davered00ss

iTrader: (4)

NOrmally after a head swap, it takes a while to get the air bubles out of the system. Keep an eye on the coolant and fill. Bubles should work themselves out.

Viper

iTrader: (6)

I road raced a set last year in June and it was 90 degrees out, 10 30 minute sessions. Stock water pump, 10.93 compression. Never went over 200 on the dummy 99 gauge. Stayed a hair under. 160 thermo.

eb02z06

iTrader: (18)

Tony it only happens at idle-not cruising or beating on the car-idle only. All the cars have stock water pumps.

vettenuts

iTrader: (4)

Two suggestons. First, I helped a friend install a cam last summer and prior to re-installing the radiator we decided to rinse it out even though it looked pretty clean. You wouldn't believe what came out of the radiator yet from a couple of feet away it looked to be perfectly clean. Second, when I re-fill, I have the front of the car in the air so there is tilt to the motor. I think this helps quite a bit with regards to getting all the air out of the block.

davered00ss

iTrader: (4)

How long have the heads been on the car?

I've never had a problem once the air got out.