Locost in heat
 

Hi,
I think I cooked my car again at the Road Atlanta race last weekend. Everything was fine and I was pulling from Corvettes when two cars laid lots of oil simultaneously into 10 and 1 corners and the race was redflagged.
While parked temps were around 220-230 F and did not seem to get lower inspite of running the fan. Water was puking out from my small catchcan.
So I shut down the car and after about 10 minutes yellows came back and I tried to start the car. Did not like to start, and I had to let people past. I used uphill on one to bumpstart the car and got it running eventually.

Now I am looking for cooling system which would allow redflag stops from full song in 100+ F heat.

The current plan is to put big and thick radiator into the back of the locost with a fan or two, and use the front nosecone for oilcooler and intercooler.
Also electrical waterpump might be in plans, so I could circulate water without running the engine in these extreme cases.

Any suggestions of sources?

hrk

CSF makes a big one for cheap. If you need something narrower like a honda radiator, CSF makes those too. I got mine from radiator express.

Also, coolant reroute for a track car. I think jason c recommends an oil cooler as well.

hrk you need a race car radiator - something that's at least dual pass, crossflow and twin 1" rows. Hopefully you can find something that will fit. I got a circle track stock rad for my Miata from randysracemart.com - specs as above with custom sized inlet/outlets for $220. You can pick up a used spal 16" straight blade 2700cfm on ebay for $70 from one of the guys that sells used nascar parts. That's about half new.

Yep, this is what is installed at the moment

GRI-2-25135-X
Overall Width (in): 17.000 in.
Overall Height (in): 18.500 in.
Overall Thickness (in): 3.000 in.
Row Quantity: Dual-row

Fan is stock Miata fan.

hrk

Damn- yeah, I'd agree, you need a good fan. Spal also makes a 3000cfm straight blade. I only recommend the spal because they seem to pull as advertised... important in this case.

Also, if you don't have the radiator sealed to the nosecone, that would help. http://www.flyinmiata.com/westfield/racingflip.php?x=33 for an example.

Yep, got that too. Or AC foam seal jammed between nosecone and radiator.

It does not help when I have IC partially in front of the radiator.

http://russmarshall.com/v/cars/cmc7/...10961.JPG.html

How about that electrical waterpump? Would I need it if I put 30" wide/4" thick/16.75" tall used Nascar radiator on the trunk or does the stock Miata pump provide enogh flow to push water to the other end of the car without problem? The other reason for electrical pump would be having possibility to use the fan(s) and pump to cool system down without running the engine.

hrk

You're not overheating on the track are you? Just the sitting still - right? Swap the fan first.

Well, it prevents me stepping on it for full 30 minutes race. In summer I have to short shift earlier and modulate gas more than in winter ambient temps.
But it is ok for 15-20 minutes and with cool down lap it kept the water in until last weekends very high ambient temps, where it puked out half a quart after each session.
I'd think the cooling is marginal at the best and red flag pushed it over the limit.
Fan would help, but the 100+mph wind is more efficient pushing air through the radiator at speed.

Also oil cooler would be helpful, but there is no great place to put it in small nosecone.

hrk

What are the oil temps? That's one sure way to drive up coolant temps. You don't have to put the cooler in the nose- especially at the speeds you're running. Older 911s just had a hard steel loop in a fender well- and the long lines from the rear. I don't think it would take much of cooler to make a difference either.

Unfortunately no record of oil temps. I have Bosch sensor there but it is not connected to data aquisition or any gauges at the moment.

The setup is the same as in this dyno thread:
https://www.miataturbo.net/dynos-timesheets-21/no-not-another-dyno-thread-8043/

hrk

Hey, how do you have your oil cooler hooked up? Do you have one of those sandwich thermostats or do you have a remote mount with one of those mocal thermostats?

cupcar, what is that black plastic stuff you warm up and bend to make underbody ducting? I would like to get some but I can't find it on BSR. What is it called?

maybe try some WI on the Rad/IC as well :dunno: I would be tremendously surprised if the stock WP could psuh water to the back of the car and forward agian. I would love to see an electric WP solution for the miata, though it just makes sense, if you wanna make a bunch of power.

I dont think it would take that much more work to suck the water horizontally.

And the stock pump doesn't push unless I am mistaken. It is a very loose design that would appear to generate suction at the inlet rather than generating positive pressure at the outlets. As long as there is a continuous column of water between the inlet and the radiator, it should work exactly the same. It shames me to say that I had to take apart the cooling system nearly half a dozen times and discuss online before I properly understood how it worked.

I find it easier to visualize the coolant system by following things from the inlet backwards to the pump outlet. Inlet side restrictions have a much strong effect on where flow goes than outlet side restrictions.

I think HRK has big oil temps. Figure a Spec Miata running normally aspirated sees 260f during a 20-30 minute sprint race. Where would that put a turbo'd engine making double the power?

Go to bsrproducts.com and type "black plastic" in the search box. The first six products are various forms in which you can purchase it. Heating isn't mandatory- it will bend well with some force.

I'm using a cheap-o hayden sandwich plate with built in tstat. It works, but has 3/8" npt ports - and I believe the mocal has the "real" tstat and 1/2" npt ports (for more dough).

You're stuck with a fairly small frontal area to get rid of all the heat generated by your level of power so you've got to get more air volume through the heat exchangers you've got. Once you get a high-flow fan in there, where does the air exit? I can't tell from your pictures if you have a belly pan under your engine or not. Perhaps some hood venting aft of the radiator/fan assembly?

http://russmarshall.com/v/cars/cmc7/...11083.JPG.html

Hood is vented with louvers and exhaust has pretty big hole also. Side pods have about dozen 2" holes from previous exhaust configurations and suspension arms have big openings behind the radiator. There is some aluminum sheet under the frame, but it has about 2" gap to the oilpan so it should vent out some in addition to gearbox tunnel which is not shileded from below.

I cannot say if these are enough or not but I don't see any bulging of my thin aluminum hood at speeds from pressure.

Oil temps are an issue and I don't have anything else than factory sleeve as cooler. Mobil one seems to take the heat decent.

Thanks for comments, keep them coming.

As an update, it seems that I'll need to change the head, compression 160, 90, 60, 180 and leakdown showed pressure escaping either through valves or directly to adjacent cylinder.

hrk

What are you running for coolant? Red Line Water Wetter and distilled water kept the temps in my ITA car under controll, with a stock radiator and fans.

I say you swap the head, install an oil temp gauge and see what happens.

I don't think it's a question of whether the oil can take the heat or not, but if the oil temps get so high that the cooling system can't manage the engine heat - then oil temp must be addressed.

Coolant is distilled water and a bottle of Water Wetter.

Rob, in addition to your suggestions I am looking for adding oil cooler as a minimum, possibly different radiator too. I have done several steps towards cooler engine and after 20 minutes of full blast the car still needs to have a break (short shifting and modulating gas for a lap) and then it is fine again.

Maybe IC is heatsoaking and causing slight pinging and thus heating the engine further?

hrk

Is the head gasket swapped?

I don't know how the emagange works- but most engine management will retard timing if air temps get elevated to prevent detonation. That can ultimately cause the combustion cycle to complete post cylinder- overheating the exhaust manifold and turbine. So then you have an extra hot turbo elevating oil (and coolant) temps.

I think your radiator is adequate. It may not have the frontal area but it definitely has the capacity, plus it's cross flow and a true double row.

A datalog would tell wonders when trying to figure out the state of the engine when it's getting hot.

I have a datalog but it mostly records my mistakes, not car events.
Speed, Throttle, AFR, RPM etc are things which I could read from DL-1 log.

I had it on but I have not looked into it yet. AFR info might help a bit.
Emanage should log too, but for some reason I never managed to log anything unless I had pc connected to it.

I am oogling monster radiator just to rule out that side, like this:
http://cgi.ebay.com/ebaymotors/ws/eB...MEWA:IT&ih=017

hrk

that's a very nice double pass rad - that's where your turbo needs it's coolant from, fittings are waiting for it. :D

Logging is preferred, but an oil temp gauge is a minimum if you're running a turbo IMO. Was the head gasket/compression issue from overheating?

Don't know if overheating was the reason for low compression numbers. Car ran ok but warm until redflag, stopping made it overheat despite fan and I presume that is when compression was lost on those two cylinders because it was hard to get started again.

hrk

Quick update.
Compression 160,90,60 and 180. Leakdown showed leakage from cylinders 2 and 3 through exhaust valve, and the leak appeared to occur in valves by each other in the middle of the head.

Pulled the head out and found no crack or nothing visible under first look. Rotated exhaust cam and these two suspectible valves moved slightly sideways just when they were closing, just like if the guides were worn.

Strange co-incidence that guides wore out just at the same time as motor overheated.
Any similar experiences or ideas what to look for once I pull the valves out?
hrk

I have a buddy who had a retainer breack on him on his ca18 recently, he only noticed this after rebuilding his head :rofl: so check those as well.

Colin's original cylinder head that had the greddy on it, had bad guide wear and it got hot too. :dunno: Have you pulled the valves?

Interesting observation.

No, I haven't had a chance to remove the valves yet to confirm whether guides are actually worn.

Assuming my version of coolant rerouting works or the water is not there anymore to cool things down, and the exhaust valve area between 2 and 3 cylinders becomes hottest point, would it be possible that guide would expand thermally and start touching the shaft of valve and have premature wear? Once it is worn enough it might not allow valve to seat perfectly.

hrk

I'd say "yes, that makes sense" - but I'm no engine builder. I don't think there's any denying that excessive heat (whether a little or a lot) is going to accelerate wear. No doubt heat is going to reduce tolerances- usually managed by your high dollar synth oil. But if your guides are getting oiled then you've got other problems. ;) If you don't have any time invested in this head then I'd just swap- being sure to check that on the other head. Unless you have the time to start swapping guides.

We had no idea Colin's guides were in such bad shape until the engine builder showed us the excessive tolerance. That was a 60k head. Half of the mileage was "little old lady", the majority of the rest was greddy miles with a small part (maybe 6 race weekends and two turbo'd track days) being a portion. If the overheating caused the problem, then I'm sure racing on it just continued the wear. The head we ended up using had 160k on it with rare oil changes, yet was mildly driven and the guides were perfect.

I have been plugging away to get better cooling capacity for my 7 to better cope with occasional redflag situation on the track, and this is what I'll try this year:
close front view
http://russmarshall.com/d/19613-1/P3110001.JPG

top view
http://russmarshall.com/d/19620-1/P3110003.JPG

bare intercooler from rear
http://russmarshall.com/d/19628-1/P3110005.JPG

Oil cooler will be on drivers left and intercooler close to intake at drivers right side. I hope I can finish some sort of sidepods to guide air and protect coolers a bit from stones from front tires before the weekend at Road Atlanta. Pod frames are made from electric conduit and will be covered with sheeting aluminum.

New pipes seem to flow better, dyno last weekend showed 192 hp at 5800 rpm with only 7 psi of boost, but AFR was 13:1 and testing was aborted. In previous configuration with smaller intercooler and otherwise similar configuration I had 12.5 AFR:s. It was free baseline only so no adjustments were allowed, I'll see if I get to go there before weekend to verify my 10% adjustment on the fuel.
THe motor is just another junkyard one with supposedly 90 000 miles, I want to sort out the auxiliaries before spending any money to the engine.

hrk

fuck, wrong thread.

I think that's going to work... I don't see how it can't. Of course you'll have some new air to break through now. :D

Well, eventually the rollcage and rear tires would break through the same air so no additional fronta area has been added. More internal resistance and turbulence for sure, but now all coolers have their own inlets and outlets.

hrk

Something that I've seen turbo locosts get away with (overheating-wise) is to mount an intercooler from the sierra or escort coswortch in front of the aeroscreen. It doesnt look very good, but works (the cosworth ic is about 4(d)*4(h)*20(w) inches).
Seems like turbo locosts typically get overheating problems due to fitting rad+oilcooler+ic in that narrow nose cone.

Your sollution with placin the rad in rear sounds even better though, but is a bit more work.

too bad about the valveguides, what coolant reroute do you run?

The coolant 'reroute' in my case is connecting the rear outlet of the head into radiator inlet instead of recirculating hot water back to engine. See
http://russmarshall.com/d/19617-1/P3110002.JPG
And under the temporary location for airfilter, one can see where 3/4" hose connects to metal part of upper radiator hose. At the engine end there is place for mechanical water temp gauge.

hrk