Xenogenesis402

Well we just finished our race in homestead the past 2 days for the SARRC/ECR enduro/Regional event. We did the regional/SARRC and came in 1st! Our first win with this car.

My question is that when we were walking through the pits we noticed on one of the speedsource cars that they had a full ductwork system for the intake... now last i heard that was illegal. We actually had that on our car when we first bought it (came with it) and someone said that it was not legal to have ductwork going to your intake. Well this speedsource car had almost a ram air setup coming from just above the radiator ductwork, took a hard left and connected to a sealed box for the intake. This would help tremendously, and specially with this heat down here.

So would anyone be able to elaborate it for me? Legal or no?

Oh also, our car was overheating pretty bad throughout the race, and I dont understand why. We have a monster radiator, water/oil heat exchange, water wetter, and a splitter... and it still runs 210-215 when i'm cruising alone and it shot up once to 228 at which i had to back off a little bit... but the last 2 laps of the race (it came down to the last turn of the last lap) we just went ***** to the wall and didn't care about the temps. It never went over 225 after that but still i know that is extremely unsafe temp from what i understand. Could something inside the block be affecting it?

wrankin

My reading of 17.1.4.D.1.c in the GCR is that as long at the ducting is kept within the confines of the engine comparment, and the hole in the front valience is legal, then you can duct away. After all, the stock intake had an enclose box fed by a duct.

Then again, I'm not a scruitineer, nor do I play one on the web.

-b

jgrewe

iTrader: (1)

A few years ago there was a clarification of the angle of the stock radiator and ducting from the side of it. As long as the intake for the ducting is not pointed into the airstream for ram air effect it is probably legal.
As for cooling, a water/oil heat exchanger isn't enough for track use. We tried one from an ARCA car that we had laying around and had the same problems you had on an EP car. We now run two stock oil coolers running in parallel. Since that change we have no problems even in the summer Fla heat.

Eagle7

"Air intake source shall be within the confines of the engine compartment or stock location."

The stock location for air intake on that car is the compartment forward of the top of the radiator where the hood latch is located. It is ducted from there over the radiator and over to the airbox. If the air flows through the stock grill openings, then up into this compartment through the unmodified stock plastic panels that separate it from the radiator, I think they are golden. If they've removed the plastic panels I think they're questionable. Do they go over the radiator with the duct, and if so, how large a duct did they fit in there? I tried to use something larger than stock there but ran out of real estate.


WRT your overheating, a few questions:

1. Do you have underdrive pulleys for the water pump?
2. What about your thermostat?
3. Do you know what your EGT or AFR is at high RPM? My car tended to run quite lean at high RPM. EGTs over 1900 and very hard to cool.
4. Are you also measuring oil temp? What does that run?

Xenogenesis402

I did not know that the factory ducting came from that area. From the way you described it sounds like exactly how the speedsource car had it. This is my first rx-7 so i've never seen a stock one under the hood. lol

1) the guy who re-did our engine after we bought the car said he did change the water pump pulley to keep the water from cavitating.
2) The T-stat was disabled so it isn't controlling temps anymore.
3) EGT's we do not know but the a/f ratio was: @ 4k = ~14.7 | @ 6k = ~13.8 | @7500 = ~13.4
4)Oil temp varied during the race from 230 away from traffic and about 240-243 when drafting and in heavy traffic.


That's all i got right now. We're actually going to install an EGT gauge hopefully before the next race to get a good feel for what's going on. Do you guys run 1 per rotor or do you have it where they collect together or just read it from 1?

And jgrew, that's an interesting idea for keeping the temps down, that doesn't block too much of the airflow for the water radiator?

Thanks for your help everyone.

Eagle7

You should bring your oil temps down, too. I spent last summer reworking my cooling setup, and it made a big difference.

I moved my second oil cooler to the space above the round cross member. I added sheet metal so air through the grill flows through this upper oil cooler. Air through the splitter flows through the lower oil cooler.

You need to block off any air paths around the radiator, so that all the air entering the grill/splitter flows through it. I blocked off all the paths around the oil coolers as well, so that all the air had to flow through one of the oil coolers, then through the radiator. That was too much - oil temp around 180 and water temp around 240. I'm in the process of adding more paths around the oil coolers so the radiator gets more fresh air. Eventually I'll get it balanced.

I've got a dual EGT gauge. I find it handy to see if I've got a fouled plug, and as good cross check, but the wideband AFR gauge is much more important.

Xenogenesis402

That is very helpful information, thank you. See we haven't blocked off the whole area to keep air from leaking out of the ducting. I'm sure that will help a bunch. And i'll also see what we might be able to do for a second oil cooler. Do you think combining 2 oil coolers and the heat exchanger would be too much? dunno if the oil pump can handle that much fluid ( or if it matters).

Thanks again.

C. Ludwig

iTrader: (27)

I setup the dual cooler the way Marty did initially. The 2nd cooler blocked too much cool air from reaching the radiator. I ended up dropping the 2nd cooler below the stock location and everything was fine. I didn't find a need to truely duct the oil coolers. Just closing off all the opening for the radiator did the trick.

I'd check with ISC on your cooler. They actually recommend the water/air cooler. As long as it's sized correctly and the radiator is large enough to accomodate the heat it should work. It's possible the cooler itself is fine but the radiator and/or ducting is the problem.

Not only are you doing the engine no favors at all running at that temp you are sacrificing a good amount of power as well. The a/f ratios aren't terribly lean but you are probably near lean best torque. You could fatten the fuel up, not lose power, and run the engine quite a bit cooler.

Xenogenesis402

Yeah see we are actually running the entire ISC setup with the monster radiator, stock oil cooler, and heat exchanger so all that should match up good. But i know there are some big ol' holes in the ductwork that air is getting by.

And as far as the a/f, what is a good a/f ratio across the board for these cars? I'm only really familiar with a boosted 4-cyl running no leaner than 12.3 at WOT... what's the range for these n/a rotory's?

You all have been a big help, definitely gonna seal up the ductwork and I am gonna look into the factory intake ductwork or something. And any other opinions or comments are welcome.

j9fd3s

iTrader: (3)

thats interesting. i had a chance to really look at the stock intake setup, and its sealed. there is a little plastic peice (mazda says plate seal front bumper fb01-50-071) that goes from the top of the grille opening to the square bar the hood latch support is bolted too. and then they have the plastic between that and the radiator. so basically the area that the intake is ducted too, stock, is closed off.

Eagle7

I think there are some pretty good sized leaks, especially around the hood latch. There's a high pressure area on the radiator side of the plastic panels and low pressure on the intake side, so it may be reasonable to leak enough air through to run a stock system.

That being said, it's not enough to run an ITS car in my experience. I've got a cone air filter located at the AFM with an inlet hose fitting in the end. The hose runs up to the stock plastic duct on the top of the radiator that sucks from this location that we've been discussing. When I tried to get all the intake air from there I got lots of pressure drop, so now it just adds some cool air to the mix.

ccanepa50

iTrader: (1)

Dont know if it's been said but dont think of a temp guage as precise, it is only relative........you always need to verify a temp guage acuracy, I find they can be off by 20º or more, stick a thermometer in the rad or dip the sensor in some boiling water and thermometer it at the same time, establish a true reading to compare to.....chuck

speedturn

iTrader: (1)

A lot of cooling problems are really mis-managed air flow problems.

APEXL8T

Gut the thermostat. Dont take the guys word for it.Also you should be able to tell the condition of the radiator if there is crap in your water and by looking into the neck at the buildup.Nothing but water and waterwetter untill winter storage..or freezing nights.

C. Ludwig

iTrader: (27)

Good advice. Gut the thermostat and make sure to plug the bypass hole under the thermostant in the water pump with a 1/2" pipe plug.

C. Ludwig

iTrader: (27)

Good advice. Gut the thermostat and make sure to plug the bypass hole under the thermostant in the water pump with a 1/2" pipe plug.

As far as a/f ratio somewhere in the 12.5-13.5 range. You'll need a dyno to find the sweet spot.