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BoxheadTim
BoxheadTim SuperDork
8/29/11 9:42 a.m.
Keith wrote: You'd be surprised at how important fans are at speed. While you might have 80 mph airspeed over the body, the high pressure in the engine bay usually means quite a bit less over the rad. You're not just hanging that radiator out in the breeze.

That's why I'm concerned not only about the lack of ducting but also that part of the wheelarch liners and other plastic panels have been removed, which gives the air a really easy way to go past instead of through the radiator.

Keith wrote: One of my Miatas had a persistent overheating problem on the highway, and it was a good set of fans that finally fixed it. Ducting is important, but if the car is overheating at slow speeds as well I'd start with the fans. Good fans (big fat ones, not slimline ones with no torque) and a sealed shroud.

I've got one decent fan (12" SPAL, but it is a slimline fan and there's a space issue fitting a "fatter" one) that seems to be just about able to keep the temperatures below 230F when the car is idling. The second (a/c) fan however is a bit of a joke - it's somewhere between 8"-10", but the way the i/c piping is run currently prevents me from fitting a larger fan. Plus thanks to other packaging issues even the slimline fan is so close to the turbo/downpipe/screamer pipe that you can see the housing having started to melt a little from the heat.

At the moment there isn't a chance in hell that I can get a radiator shroud in there either - there are a couple available for the DSM with decent fans but they all have fitment issues with the current setup.

Keith wrote: I get my metal at the local metal supply shop. It doesn't make sense to ship a 3x3 sheet of alloy.

That's what I was thinking, it just seems to be surprisingly hard to find this type of shop around here.

iceracer
iceracer SuperDork
8/29/11 10:06 a.m.

I bought 2x4 or sumthin sheets at Ace Hardware

Keith
Keith SuperDork
8/29/11 10:40 a.m.

Just for fun, spend some time on the SPAL website and look at the fan ratings and how they drop with increased static pressure. That shows how the fan copes with pulling through multiple heat exchangers.

If it were me, I'd be looking into reconfiguring things (moving the radiator/IC, changing IC pipes) to get a proper shroud and some fat fans on there. Shrouding is a good idea, but fans are crucial. Obviously I haven't seen the packaging you're dealing with and I'll bet it won't be easy, but it might be the best solution over the long term.

mad_machine
mad_machine SuperDork
8/29/11 1:15 p.m.

I Ithink you nailed the problem with the lack of stock liners and sheilding. Air will take the path of least resistance.. and a radiator provides a LOT of resistance

BoxheadTim
BoxheadTim SuperDork
8/29/11 3:45 p.m.
Keith wrote: Just for fun, spend some time on the SPAL website and look at the fan ratings and how they drop with increased static pressure. That shows how the fan copes with pulling through multiple heat exchangers.

I did that last night - it drove the point home that I'd need to get a $180 fan if I wanted to see some improvement over the current fan . And yes, they do drop quite scarily...

Keith wrote: If it were me, I'd be looking into reconfiguring things (moving the radiator/IC, changing IC pipes) to get a proper shroud and some fat fans on there. Shrouding is a good idea, but fans are crucial. Obviously I haven't seen the packaging you're dealing with and I'll bet it won't be easy, but it might be the best solution over the long term.

Part of the problem is that the PO actually made the packaging issues considerably worse - he welded a bung for the wastegate onto the front of the OEM manifold so now I've got the wastegate with its screamer pipe filling a lot of the space between the radiator and the manifold. Plus the GM MAF conversion takes the place that the OEM expansion tank normally occupies so he was running it without expansion tank (doesn't seem to be that uncommon in the DSM world, but I thought it was a bad idea as it tends to leak coolant that way) so now the only expansion tank that we could barely fit in there (because the IC pipes severely limit the space) is also covering a corner of the fan, further reducing airflow.

I'll try to sort out the issues with the IC piping - unless I'm completely off base an additional 90 degree hose and a bit of 'persuasion' should sort that out - but that's only the first step.

In order to sort out this packaging mess properly, I'd need a new exhaust manifold, a different turbo (preferably with an internal wastegate) with a turbo blanket so it doesn't melt the second fan, a different type of IC to throttebody piping so I can relocate the MAF to make space for the header tank again and a new header tank. That's basically another grand if I buy reasonably priced parts...

At the moment the idea is to get the car running mostly OK so I can figure out if it's worth throwing that sort of money at the car - I don't want to throw another grand at it in the hope that I can get it running OK only to find out that I've just ended up another grand deeper in it.

Keith
Keith SuperDork
8/29/11 4:53 p.m.

You can get some decent fans from production cars for cheap. But it sounds as if freeing up some space will definitely be challenging.

4Msfam
4Msfam New Reader
8/29/11 8:13 p.m.

Could you rig another wiper washer tank in there? Point the spray at the radiator... push to cool?

BoxheadTim
BoxheadTim SuperDork
8/29/11 8:18 p.m.

I've been thinking about that (Evos have them rigged up to spray the I/C) but again, distinct lack of space...

There's also the issue of fixing the symptom rather than the cause.

mad_machine
mad_machine SuperDork
8/30/11 12:13 a.m.
BoxheadTim wrote:
Keith wrote: Just for fun, spend some time on the SPAL website and look at the fan ratings and how they drop with increased static pressure. That shows how the fan copes with pulling through multiple heat exchangers.
I did that last night - it drove the point home that I'd need to get a $180 fan if I wanted to see some improvement over the current fan . And yes, they do drop quite scarily...
Keith wrote: If it were me, I'd be looking into reconfiguring things (moving the radiator/IC, changing IC pipes) to get a proper shroud and some fat fans on there. Shrouding is a good idea, but fans are crucial. Obviously I haven't seen the packaging you're dealing with and I'll bet it won't be easy, but it might be the best solution over the long term.
Part of the problem is that the PO actually made the packaging issues considerably worse - he welded a bung for the wastegate onto the front of the OEM manifold so now I've got the wastegate with its screamer pipe filling a lot of the space between the radiator and the manifold. Plus the GM MAF conversion takes the place that the OEM expansion tank normally occupies so he was running it without expansion tank (doesn't seem to be that uncommon in the DSM world, but I thought it was a bad idea as it tends to leak coolant that way) so now the only expansion tank that we could barely fit in there (because the IC pipes severely limit the space) is also covering a corner of the fan, further reducing airflow. I'll try to sort out the issues with the IC piping - unless I'm completely off base an additional 90 degree hose and a bit of 'persuasion' should sort that out - but that's only the first step. In order to sort out this packaging mess properly, I'd need a new exhaust manifold, a different turbo (preferably with an internal wastegate) with a turbo blanket so it doesn't melt the second fan, a different type of IC to throttebody piping so I can relocate the MAF to make space for the header tank again and a new header tank. That's basically another grand if I buy reasonably priced parts... At the moment the idea is to get the car running mostly OK so I can figure out if it's worth throwing that sort of money at the car - I don't want to throw another grand at it in the hope that I can get it running OK only to find out that I've just ended up another grand deeper in it.

wow.. that is common? no wonder most DSMs are no longer on the road

92CelicaHalfTrac
92CelicaHalfTrac SuperDork
8/30/11 5:21 a.m.
BoxheadTim wrote:
ncjay wrote: Exactly how hot is the car running? Low speeds the fan(s) should keep it cooled off and above 40 to 50 the airflow should be decent enough. Yeah, those gaps around the radiator sure aren't good. Sealing them up should help. Summer's coming to a close. It shouldn't be such a problem in a few weeks.
The "impending headgasket failure" light comes on at 234F and I've seen water temps up to 250F-ish when I couldn't pull over in time. Amazingly enough I haven't seen any signs of actual head gasket failure so far... Typical one was a trip to the store on Saturday - outside temperature was in the mid-nineties and it had trouble keeping the temperature in check in the 25mph.

If you've got a good headgasket and some solid hardware, i doubt you'll be blowing the gasket at 250f.

I've seen 270F on my MX6, and i suspect it's due to the same issues as what you're describing here if i must be honest. No headgasket blowing yet. (Although mine never really goes above 220F if it's at speed, no matter what i'm doing to it.)

TRoglodyte
TRoglodyte HalfDork
8/30/11 10:14 a.m.

Could the altitude be causing some of the problem? Lack of air density, or a lean fuel condition?

Karl La Follette
Karl La Follette Dork
8/30/11 3:15 p.m.

Real estate signs

BoxheadTim
BoxheadTim SuperDork
8/30/11 3:41 p.m.

I think the real estate agents have gone to plastic out here. Too many houses for sale .

The altitude might be a problem, but I think that's more of a secondary issue. At least when it's running in closed loop mode, the datalog shows that the O2 sensor is switching, but of course there's a chance that the PO didn't quite get the map right once the car switches into open loop. In fact, given that he tuned old school with a pyrometer, that wouldn't be a surprise at all.

One of the items on my to-do list for this weekend is to fit my wideband O2.

BoxheadTim
BoxheadTim SuperDork
8/30/11 3:45 p.m.

In reply to mad_machine:

Actually the guy I bought the Talon from was quite clued up, especially as DSMers go. Some of the people posting on some of the DSM forums make your head hurt, but they're convinced that they already know everything.

Nevertheless the "cheap speed" attraction is a problem with these things.

ransom
ransom HalfDork
8/30/11 3:49 p.m.

One and a half more observations on the aluminum acquisition front: Metal Supermarkets is another chain supplier worth checking for in your region. The other thing to note is that it's worth finding out how much for more of/all of a sheet; the cutting fees can pile up, and the cost per area skyrockets for smaller quantities.

BoxheadTim
BoxheadTim SuperDork
8/30/11 3:57 p.m.

Unfortunately Metal Supermarket's closest shops are down in the Bay Area, that's an 9-10 hour round trip, but thanks for the recommendation.

HappyAndy
HappyAndy HalfDork
8/30/11 4:43 p.m.

Just a thought. You said that there was a good size gap between the IC & radiator. Is the gap large enough to stuff fans in, so that you would have a "fan sandwich ", with the fans pulling air through the IC than pushing through the radiator?

fasted58
fasted58 Dork
8/30/11 4:53 p.m.

home builder supply (not the HD, Lowes type) or commercial roofers. We used to get sheets and cut offs there for a late model, commercial grade .040 oughta work n it's easy to bend and form

BoxheadTim
BoxheadTim SuperDork
8/30/11 5:05 p.m.
HappyAndy wrote: Just a thought. You said that there was a good size gap between the IC & radiator. Is the gap large enough to stuff fans in, so that you would have a "fan sandwich ", with the fans pulling air through the IC than pushing through the radiator?

I'll have to have a look at that - there might be, but it might not be feasible due to mounting issues, and there's at least an a/c evaporator somewhere in there, too. That would be very useful if it was possible.

Curmudgeon
Curmudgeon SuperDork
8/31/11 6:46 a.m.

Can't help you with metal, but I do have a suggestion: make sure your fans are wired properly. We had one in the Mercedes shop recently that had one replacement fan wired with the wrong polarity, when the fans came on one was pulling and one was pushing but both were supposed to pull. It would overheat randomly at highway speeds.

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