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-   -   Racing FD on hot days (https://www.rx7club.com/race-car-tech-103/racing-fd-hot-days-352622/)

ORX705 09-27-04 11:03 PM

Racing FD on hot days
 
The hotter months are approaching (Australia) and am wondering about the FD’s capability to race in 40degC (100+Fahrenheit) ambient heat (track temps even higher). My car is virtually stock, only running a down pipe, gutted cat, cat back system at 9psi of boost. I have started running with the heater and AC fans on. Do you think the cooling system and stock intercooler will cope with sets of 5 laps?

rynberg 09-28-04 02:53 AM

Pull the A/C relay to run the fans on high (or otherwise rig it). You should be ok if you're radiator is well sealed, but it would really help if you have dual oil coolers. I strongly recommend getting an aftermarket water temp gauge to make sure things are ok -- stock gauge = not enough warning.

Fatman0203 09-28-04 03:11 AM

Replace radiator (ITS A MUST NO QUESTION)
Dual oil coolers or a fat single.
Aftermarket temp guage.
Ducting

Dameon's car ran in Laguna Seca I think ( he has the video). For auto-x I dont see a problem since its a short burst and you can open her up later to cool off but for track conditions I highly suggest it.
A better stock mount may help intake temps too. Also fab up a nice REAL cold air, not hot air after the radiator , intake. Dameon also did that.

DamonB 09-28-04 07:34 AM

Sets of 5 laps should be fine if your car is perfectly sound. My radiator is completely stock but I did seal the side of it to the inlet; this makes a nice improvement. Keep an eye on coolant temps and short shift when they start to rise too much. I find great improvement in temps by shifting under 6500 rather than 7000. Run with the heat on full blast and consider making an extended front lip for track use. It works for me. Front splitter

adam c 09-28-04 10:51 AM


Originally Posted by rynberg
......... I strongly recommend getting an aftermarket water temp gauge to make sure things are ok -- stock gauge = not enough warning.

Knowing your "real" temps is a must. Get a water temp gauge. Without one, you really don't know anything.

Fatman0203 09-28-04 11:21 AM


Originally Posted by DamonB
Sets of 5 laps should be fine if your car is perfectly sound. My radiator is completely stock but I did seal the side of it to the inlet; this makes a nice improvement. Keep an eye on coolant temps and short shift when they start to rise too much. I find great improvement in temps by shifting under 6500 rather than 7000. Run with the heat on full blast and consider making an extended front lip for track use. It works for me. Front splitter

Wouldnt he be able to go at least all out with a radiator for alot longer? I think even though it can "take" the heat you shouldnt have it there if its not needed to be.

adam c 09-28-04 12:00 PM

The stock radiator actually works pretty well for anything except road racing on a warm/hot day. The plastic end tanks are not as reliable as the "all metal" aftermarket radiators, and that is the reason many people replace them when the stock unit gets old.

DamonB 09-28-04 12:17 PM


Originally Posted by Fatman0203
Wouldnt he be able to go at least all out with a radiator for alot longer? I think even though it can "take" the heat you shouldnt have it there if its not needed to be.

I don't have any coolant issues with the stock radiator with the inlet sealed up. I only gets temps out of control during long track sessions in 100+ degree weather. When temps start climbing I can usually keep them down by short shifting as I believe the coolant temp goes up not from hard running but from water pump cavitation. I can make instant differences in temp just by shifting sooner even though I'm still boosting hard. I'll fit an under drive waterpump pulley soon and this will tell me right away if it's cavitation or not. The lip helps too.

An aluminum radiator is certainly a better built product than stock but it's not the must have item the majority of people claim.

Umrswimr 09-28-04 12:50 PM


Originally Posted by DamonB
An aluminum radiator is certainly a better built product than stock but it's not the must have item the majority of people claim.

And not allowed in SOLOII stock class. :)

ORX705 09-28-04 04:34 PM

thanks for all the comments. I just needed to be reassured that i wasn't going to cook the engine. all the Aust models came out with dual oil coolers which is comforting. it has been laziness on my part that i havn't installed a temp gauge. for now if i ever see the temp gauge move from half way i'll take it easy and depart the track (well that was the plan, only really get to check it down the straight)

i'm looking at fitting a SP RX7 intertcooler but i don;t want to push my luck with the stock ECU

rynberg, info on removing the ac relay is gold. i usually run the ac with out the fuse

John Magnuson 09-28-04 07:15 PM

Yes, an underdrive pulley make a huge difference if you're going to run at sustained high RPMs. Mazdacomp recommends you do it and I have to admit that underdriving the water pump pulley 25% was the last thing I tried. It made a huge difference. Although I avoid 90F and above track days like the plague I have had no cooling problems at all since the underdrive pulley install. I've even gone for about 45 minutes staight at Laguna Seca in 80F weather. (had to pit for gas!).


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