I'm trying to help a Newbie on here with moderate overheating problems with his IM.  He has a 1915, not full flowed, no external cooler and it's getting up around 220F on highways in summer heat.  He sent a bunch of photos and there is no opening in the firewall right in front of the fan inlet.  

Is this normal for most IM cars?  

Has anyone opened up the firewall in an IM, with a hole to let more air in?

I've got him thinking about which external cooler he wants to buy, and CB Perf. has a "full flow" oil pump that pulls oil off at the oil pump cover and returns it to the oil pump cover so no drilling and tapping the case - Interesting:

https://www.cbperformance.com/product-p/1786.htm

That would allow an external filter, too.

Anybody on here used this approach?

While his local mechanic (who seems to know air cooled engines) thinks that 220F is OK, both the owner and I would like to see something closer to 200-205-ish so that's the rationale for the added cooler (just like the rest of us).  I suggested a DeRale 16-pass fan assist cooler, but I know a lot of you run Setrab units.  Do they offer one with an integrated 180F thermostat switch or should he just look at those at CB Perf?

https://www.cbperformance.com/...ccessories-s/255.htm

Thoughts would be welcome.

Original Post

You are correct, Gordon-- IM doesn't put a hole in the firewall.

As documented elsewhere, I listened to conventional wisdom and put two 8" holes in mine, along with reversible fans (push or pull). I monitor all 4 cylinder head temperatures as well as oil. The holes/fans do absolutely nothing, and may even make the situation worse. If I had it to do over, I'd leave things as they were.

Everybody has an opinion, and here's mine. The area under the car is a low pressure zone and the oil cooler and cylinder head waste heat is being dumped under there. Trying to get air into the fan intake (which is the only place the matters) by means of a hole leading to this hot, low-pressure zone is a fool's errand.

If you want more air-- I'd open up the deck lid rain tray or put a hole behind the license plate or both. The theory can be tested by having him drive around with the deck-lid popped a few inches (held open with some gizmo or other). 5 bucks says it'd help.

But if a guy is running hot, IMHO, the first order of business is to get a decent exhaust. In my experience, the exhausts guys try to run on bigger engines have the net effect of stuffing a potato up the tailpipe and expecting 180* oil temperatures. After that, I'd get a 96 plate (or Setrab) oil cooler (with fan) with a nice thermostatic bypass. 99% of the cool running replicas out there have nothing more than this stuff done-- no hacking up the car in any way.

That's my opinion. Everybody's got their own. Your mileage may vary.

Last edited by Stan Galat

I have a VS not an IM but I think my experience might apply. My VS has no hole in the firewall as the car was built in 2001. I'm not sure when Kirk starting cutting the holes in the firewall. Anyway, I had a stock 1776 with no external coolers etc. The first summer I owned the car the gauge said the car was running hot. I added the bolt on oil pump with the external filter (although I don't remember which one anymore) and a Setrab fan pack with a 180* thermo switch

Those modifications worked just fine for that motor. I didn't go full flow until Pat built me my current 2110cc motor. I'm still using the same Setrab and I have zero issues.

Robert, is the fan switch screwed in to the cooler assembly somewhere?  Something like that would be ideal.  Mine is a separate switch with a small, separate housing in one of the oil lines and while not ideal, it works.

I think we're both resigned to adding an external cooler and moving on.  Just trying to decide which one is popular and get it in there.  While he's doing that he can add an external filter for added goodness.

Thanks for the IM info, Stan.  Just what I was looking for and we totally agree on the need for the external cooler.  That idea of propping up the engine lid should have occurred to me but didn't, so thanks for jogging my memory ("Some call it jogging, but I call it running around" - Jimmy Buffet).

I'll look in to the exhaust - no idea what's on there, but probably not an extractor....   I'll find out.

So, in order, (1.) try propping the cover open on a hot day, (2.) get the external stuff ordered as he'll probably benefit from that no matter what.

Anybody else running something other than the cooler Robert mentioned???

Thanks!  gn

What sort of shroud is he running? I spent about 8 hours reading a Samba thread that Jake, Clark, (Volkaholic) and several other luminaries participated in. Two main points I got before I bought my replica Thing shroud:

  • Engines under 2L shouldn't require any external cooling
  • 90% of aftermarket shrouds are crap. They don't have the correct internal baffling to properly cool the engine. 

In testing Jake did, the only thing that came close to his DTM setup was the Thing* shroud. I don't have specific temps, but my 2L motor used to get right up to the red line on the temp gauge pulling grades or long freeway runs at 4,000 rpm.  Installing a Thing Shroud and TypeIV oil cooler solved that. I can run flat out all day and my temp gauge never gets past 12 o'clock high. 

 

*According to someone who posted in that thread, because of the low speed, low RPMs VW expected Things to run off road, theyre-engineered the shroud and it's the most efficient one they ever made.  And supposedly all Brazilian and Mexican VWs used it from them on. I bought mine from a Canadian company, but AAPiston sells them now, with and without heater holes. 

 

My engine is a mild two-liter.

I have a VS with the hole through the firewall and a fan behind the hole that pushes even more air into the engine compartment. (I didn't know if this was going to help or not - I did it in the interest of Science.)

I also have a Setrab fanpack in the driver wheel well, but NO Mocal sammich, so the cooler is always in the loop. And the cooler fan is on a manual switch (no thermostat), so I know exactly when it's on and can watch the effect on the temp gauge.

Turning on the cooler fan makes a big difference. You can see the temp drop on the gauge, usually within a minute or two.

I turn the fan on when the temp reaches mid-gauge, which I think is about 200 F. I don't think I could comfortably run this engine in this climate without an external cooler. When ambient temps are below about 70F, I don't need the cooler fan, but by 75F, I definitely do. Even on 90-plus degree days, the cooler keeps temps just slightly above mid-gauge - probably about 210F.

For me, the cooler fanpack is like 'all-weather' protection. I can go anywhere in any heat, get stuck in any traffic, and still know it's not gonna overheat. I could probably get by without it on most days, but then I'd be a lot more stressed, even if the engine might not be.

Life's too short not to have an external cooler.

 

Another question I have is his oil cooler tin in place? I know a lot of builders leave it off but I always suspected hot air blowing through my oil cooler directly on my 3/4 side carburetor was what was causing my idle issues. I could set it to 900rpm cold, and it jumped to 1300-1500 when it warmed up. Turn it back down and then it wouldn't idle cold. 

With the thing shroud and oil cooler ducting installed, it idles at 900, hot or cold. There may have been other issues involved, but I'm convinced the ducting played a part.  

image

Not so much of an issue with my Spyder, but on a Speedster I'd guess that missing those bits would just be filling the engine compartment with hot air. 

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Last edited by dlearl476
 
@dlearl476 posted:
  • Engines under 2L shouldn't require any external cooling.

 

That said, I'm working with a M/C oil filter company I've dealt with for years on making an oil filter/cooler that will run with one of the CB MaxiFlow oil pumps Gordon posted. It's on next winter's to-do list. 

image

@Sacto Mitch posted:

Life's too short not to have an external cooler.

 

  I'm more interested in the filtration, but yeah. 

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I have a Setrab with the Mocal sandwich.  The fan switch can be put either at the inlet or outlet of the Setrab.  I put it at the outlet thinking that there are times when cooling is adequate without the use of the fan.

Robert, is the fan switch screwed in to the cooler assembly somewhere?  Something like that would be ideal.  Mine is a separate switch with a small, separate housing in one of the oil lines and while not ideal, it works.

I think we're both resigned to adding an external cooler and moving on.  Just trying to decide which one is popular and get it in there.  While he's doing that he can add an external filter for added goodness.

Thanks for the IM info, Stan.  Just what I was looking for and we totally agree on the need for the external cooler.  That idea of propping up the engine lid should have occurred to me but didn't, so thanks for jogging my memory ("Some call it jogging, but I call it running around" - Jimmy Buffet).

I'll look in to the exhaust - no idea what's on there, but probably not an extractor....   I'll find out.

So, in order, (1.) try propping the cover open on a hot day, (2.) get the external stuff ordered as he'll probably benefit from that no matter what.

Anybody else running something other than the cooler Robert mentioned???

Thanks!  gn

The thermal switch is screwed into the Setrab cooler. 

@Bob: IM S6 posted:

Is 220F while cruising all that bad?  Lots of people would say that's within the range for these engines.

I feel like it'd be good to respond to this. Technically: yes, 220*F is fine. 10* more is super-borderline. That's not much margin for any changes.

The owner lives in New England, where I assume it isn't really hot yet. If the owner is running 220* (which is fine) when it's 70* outside, he'll likely be running 230* (which is a lot less fine) when it's 80*, and 240* (which is decidedly not fine) when it's 90*. This assumes that the ability to shed heat from the oil is linear in increasing ambient temperatures. In my experience, it is not-- one may be fine at a certain ambient condition, and way too hot when it gets 10* hotter.

If he never left Boston and stayed home when the weather got hot, he'd probably be just fine... but that's no way to live.

Everybody has to learn to bend for their car in some way. @MusbJim is the master of this. @Sacto Mitch has found inner peace on the path of enlightenment. Both are adept at accepting the limitations of their cars and working towards being better humans by embracing those limitations.

But... they both have external coolers. 

Why? Because both of them like to drive. There's just not much utility in being limited to an ambient temperature under 95*, because one is likely to encounter that temperature at some point along the way. I don't drive a cross the desert every day, but I have driven across many deserts in my car. I'd like to keep driving, not park and wait to die of heat-stroke. I have even less desire to scramble yet another engine "driving through it".

There's an idea over on TheSamba that you build for where you live. I think that's really short-sighted. I think one needs to build for what one might encounter and need to live with-- high outside temperatures, 91 octane fuel, roads that might be less than glass smooth. Building a 13:1 engine and putting it in a car with cheater slicks might yield a vehicle that runs like a scalded dog on a cool night, while burning E85-- but it isn't particularly useful when one finds oneself traveling across the Mojave mid-day in August.

These cars are made to drive. It pains me that a lot of people never get a chance to find out how great they really are, because they are limited by a narrow band of operation. I know you know this, @Bob: IM S6, as you have the ultimate GT speedster. It just bears spelling out again for those who might come across this later.

@Sacto Mitch posted:

 

My engine is a mild two-liter.

 

I turn the fan on when the temp reaches mid-gauge, which I think is about 200 F. I don't think I could comfortably run this engine in this climate without an external cooler. When ambient temps are below about 70F, I don't need the cooler fan, but by 75F, I definitely do. Even on 90-plus degree days, the cooler keeps temps just slightly above mid-gauge - probably about 210F.

Life's too short not to have an external cooler.

 

I think I'd check.

Fan on at 200F would seem about right. I've heard guys on here say put the fan on at 180F, which seems low in an engine that likes its oil in the 170-220 range and which reportedly suffers excessive wear if operated regularly below 200F

I must make a correction to my earlier post. I started with a 180* thermal switch but moved it to a 190* thermal switch. I did this to insure I got the oil hot enough while driving shorter trips which I occasionally make. 

 

Ed, all figures are approximate and not drawn to scale.

When I first got the car, I played with a candy thermometer and tried to figure out roughly what the gauge was telling me. All I remember is that the middle of the gauge was very safe, slightly higher was mostly safe, about three-quarters was cause for concern, and near the red mark meant stop the engine.

Thirty thousand miles later, there are no funny noises, no blue smoke, and no lumpy pieces in the oil when I drain it. So, I'll continue to continue.

After a while, you can tell when the engine's happy just by listening to it and feeling how it responds. Like me, it acts different when it's starting to get hot. The gauge is useful as a reality check. Under most conditions, I can pretty much predict what the gauge will read. If it's much off from that, it's time to start poking around.

The 180-degree thermostat seems to be where most folks start, for some reason. Maybe because there's a delay in most cooling systems between when they switch on and when the oil at the pump's pickup point starts cooling down. So, if the cooler kicks on at 180, the pump will probably be pumping oil hotter than that for a while - or maybe it won't ever get down to 180 even after the cooler been's on for a while.

What I like about controlling the cooler fan with a manual switch is that I can anticipate rising temps and get ahead of the curve a little. If the gauge is already warmish, and there's a long grade up ahead, or I'm turning onto the freeway, I'll flip the switch before things start to heat up.

 

@Stan Galat's post explains exactly why I spec'd an external cooler/fan assembly on my 1915cc.  After 56k miles of Charleston summer temps, long interstate slogs to Carlisle and the mountains, and sitting in city traffic it still ran fine, used no oil, and seemed as if it could go another 56k miles. 

Mine is totally automatic because, well, I'm East Coast and Mitch (and his manual fan switch) is West Coast.    It's nice to have the control that Mitch has and something to include in the driving experience, but I'm fine with being clueless, other than watching the temp gauge.  Besides, with mild ADD there is ALWAYS something trying to catch my attention so the more I can ignore (for me) the better.

So I guess the next step for Marc is to come up with either a spiffy external oil cooler kit or start making up a parts list for his own "kit".  Looks like we've got him headed in the right direction.

@Stan Galat posted:

If you want more air-- I'd open up the deck lid rain tray or put a hole behind the license plate or both. The theory can be tested by having him drive around with the deck-lid popped a few inches (held open with some gizmo or other). 5 bucks says it'd help.

That's my opinion. Everybody's got their own. Your mileage may vary.

Here's a really good (long) read about engine temp/oil temp. 

https://www.thesamba.com/vw/fo...highlight=volkaholic

It probably applies more to Speedster owners than it does Spyders, but it's useful anyway. And it's what I based my decision to replace my cheeseball shroud on. 

Not to turn this into an oil thread, but here's my 2¢: VW and Porsche spent tens of thousands of hours researching and developing a forced air cooling system for their motors.* And they work. IMO, putting an external oil cooler on an improperly designed air cooling system is nothing more than a bandaid. Unless you've got 4 cylinder CHT monitoring like Stan does, you have no way of knowing whether your P/C and cylinder heads are being properly cooled. 

 

*Granted VW/Porsche never envisioned 2300cc Type I or 2700 Type IV motors, but I trust the people who did when they tell me a properly air-cooled motor <2L doesn't need an external oil cooler. And my experience with the Thing shroud and the incorporated Type IV oil cooler backs that up. 

You’re right about the external cooler being a band aid, but for the wrong reasons.

Yes, VW designers gave us an adequate cooling system - For a 1600cc type 1 engine, and even that was aided in the final years with increased air into the engine from enlarged external grills.  Even the later 356 moved to twice as much air into the engine compartment, when they moved from the 1500 normal engine to the 1600 Super.  The cooling system for the 2liter (I’m assuming you mean the type 4, here) was (a.) vastly different from the type 1 and (b.) moves a helluva lot more air than the type 1 did.   Same can be said for the pancake type 3 and 4.  

All that aside, it was only 2/3’rds of the equation.  The other 1/3 was how they designed the car around the cooling system and turned that into an advantage.   Our Speedsters do not have that advantage.  As far as getting more cooling air into the engine, they are marginal at best and several ideas that we thought had promise to improve that situation (fans or ducting blowing into the compartment, for instance ) proved less than beneficial due to low pressure areas where we didn’t expect them (yes, someone has tested for this all over/under the car).   Just look at the orange VW sedan in the article you referenced:  Just the air grill to the engine compartment up over the lid has twice the air flow area of our single little grill.  No wonder a lot of us have opened up a hole in the firewall right in front of the fan inlet.

So, we’re starting with one hand tied behind our backs with a marginal car design and, through trial and error, some of us have developed several things that we, as a group, have seen work and incorporated in our cars, too, always with success.  Propping open the engine cover on highways, adding a fan assisted external oil cooler, having all of the engine heat shields in place, running a 1971 or later fan shroud and a larger internal oil cooler, running lighter viscosity oil; These things have been proven to reduce oil temps by 5° - 15° with no other changes to the surrounding car (We’re still talking just Speedsters, here).  Relying on the tried and true German cooling system design, with a sub-optimal car cooling design surrounding it and hoping that it will be alright has never worked for us.

Listen to us.  We have lots of people and over 20 years of messing and curing Speedster Overheating behind us.  And we haven’t had anyone seizing up over abnormally high head temps, yet.  If anything, we have people Who are running 4-cyl CHT gauges reporting lower head temps than most of us expected.  Our experience is also that most Spyder owners are running most of the same cooling tricks as the Speedster Group with very similar success.

Last edited by Gordon Nichols

So Gordon, my option is a switch or automatic.  With the automatic, like you mentioned, it switches on by itself.  Nothing I need to do?  Am i on the right track?  Thanks again group, making this newbie feel a little better!

@Marc Orloff, I have a Mocal sandwich between my oil filter and the mount.  It acts as an automatic switch to send oil to the cooler when it exceeds a certain temperature.

Also, I have a switch on the outlet of the cooler that turns on the fan when the oil coming out of the cooler exceeds a certain temperature.

I have a light in my combo gauge that tells me when the fan is on.  I think a lot of the time oil is going through the cooler but the fan hasn't come on.

@Stan Galat

“If you want more air-- I'd open up the deck lid rain tray or put a hole behind the license plate or both. The theory can be tested by having him drive around with the deck-lid popped a few inches (held open with some gizmo or other). 5 bucks says it'd help.”

I agree with Stan on his thought above. I too monitor all 4 CHT and the elec cylinder opening deck lid approx 3”, as well as cut opening behind license plate made a difference on 95 deg + FL days. 

@Marc Orloff posted:

So Gordon, my option is a switch or automatic.  With the automatic, like you mentioned, it switches on by itself.  Nothing I need to do?  Am i on the right track?  Thanks again group, making this newbie feel a little better!

Correct. The auto switch turns the fan on when it needs to and turns the fan off when it needs to. 

Last edited by Robert M

 

Marc, sorry if I may have tossed out a red herring.

I'm the kind of old-school curmudgeon who likes doing things the hard way just to be ornery.

Almost all normal people use a thermostatic switch to control the cooler fan and that's what I'd recommend for you - unless you just like being ornery, of course.

But @Michael McKelvey raises another point that's now been mentioned a few times here - the 'Mocal sandwich'.

This deals with another consequence of installing an external oil cooler. You don't always want all that extra cooling. In cold weather, you want the engine to reach normal operating temperature as soon as possible - and before you start using the engine really hard.

With an external cooler connected (and no 'sandwich'), it can take as long as a half hour for the engine to warm up if it's in the 40s or below. (Being from California, I've only read about such things in books, but it's my understanding that this 'cold' phenomenon can happen with some regularity in your part of the country.)

The 'sandwich' is a mounting plate (with its own thermostatic valve) that diverts oil around the cooler until the extra cooling is needed, so your engine gets up to normal temps much quicker. 'Mocal' is a popular brand of 'sandwich', but there are others. Gordon will probably be able to give you an in-depth explanation of how all this works.

Again, being ornery, I don't need no stinkin' sandwich, but as long as you're going to the trouble of putting in a cooler and you experience this 'cold' thing often, you should give the sandwich some serious consideration.

 

Last edited by Sacto Mitch

Now, my car is a little different, but it has its oil cooling issues too.   Two oil coolers up front, with manually operated fans - I like being able to operate switches - allows me to control the oil temperature myself.  There is a 180 degree thermostat that keeps the oil in the system until it reaches that temperature, then the oil is sent up front to the two oil coolers.

I have often wondered why 180 degrees was chosen as the point at which the oil is sent through the oil coolers, as most engines like mine would struggle to stay at 180 on any sort of warm day. 

I do know that my engine is cooled more by the oil than by whatever air the fan manages to blow over the cylinders.  That's with the grill, two sets of louvres on the lid, and a large cut out behind the rear licence plate for air entry. 

Anyway, I just wanted to post on this.  Most times I feel left out of these discussions, having chosen to go another route with my car/engine combo, but I try to ingest as much knowledge as I can and apply it to my situation.

Bob:  See my post immediately above yours.   We’re all ingesting a lot.  And your forward coolers are each a bit bigger than my one, puny DeRale way out back.  And they’re “cooler looking”, too.   

BTW, I think we can apply a rule of thumb here for the use of MoCal fluid valves.   Yes, they’re great, but mainly for managing the warm-up process, mostly when the outside temps are below, say, 40°.  I installed one because, here in the Northeast and because I’m a wild and crazy guy, I do a lot of driving when the outside temp is way down below 40° and wanted to get the temp gauge up off the bottom peg.  For that, the MoCal Sandwich valve and the fan shroud vanes and thermostat do a nice job of keeping the oil temp around 180°, right down into the low 30’s outside. 

That said, if you’re never going to be driving your summer Speedster when the outside temps are below, say, 50°, do you really need a MoCal sandwich valve?   (Marc:  It’s called a “sandwich” valve because it is installed between the spin-on oil filter and the usual mount that the filter spins on to, hence a “sandwich”).  
I would say, no.  I drove for a lot of years without one and never had problems, but I never drove below 40°.  Once I had decent heat In the car and took it out in much colder temps, the MoCal made a lot more sense.

Back to Dr. Bob:   180° isn’t what you’re trying to achieve.  What you really want is anything over 170°.  Why?  Because 170° is where water condensed in the oil/crankcase/system begins to evaporate and leave the system.  Sometimes in cold weather it is not uncommon to find a beige-colored scum on the underside of the oil filler cap.  That is coagulated water and oil that hasn’t seen conditions warm enough to evaporate or boil off the water content.  Run the engine for a while up over 180° and it all magically goes away, just like Trump’s Covid.  That is why 180° is a magic number.  Kinda like “42”.

"What I like about controlling the cooler fan with a manual switch is that I can anticipate rising temps and get ahead of the curve a little. If the gauge is already warmish, and there's a long grade up ahead, or I'm turning onto the freeway, I'll flip the switch before things start to heat up."@Sacto Mitch

This is also my set-up and habit as @Stan Galat alluded. Just something about manually flipping the oil cooler fan switch makes me feel as Master of My Domain (Seinfeld). 

Regarding switches and such-- one may prefer a belts and suspenders approach. For a while, I had my cooler fan on a thermostatic switch with a toggle switch wired in parallel. That way, I could start the fan early, should I have been so inclined, but I could also just let the thermostatic switch do it (as I did).

Regarding the need for an oil bypass, Mocal or otherwise-- I can't for the life of me figure out why a guy wouldn't use one, for the same reason that I can't understand why he wouldn't run an external cooler. Sure-- there should be no need for a bypass, assuming every trip in the car is over 50 miles, and under no circumstances will the car be driven when the temperature is under 50*. Oil that is too cold is almost as bad as oil that is too hot. Guys who live in Barstow don't need 'em... unless they drive into the mountains for a getaway with the Mrs. I sorta' like to use my car, not build my life around it.

Regarding the Sainted German Engineers and cooling-- the cooling system was the most exotic part of the Type 1, and the part that clearly had the most intellectual horsepower (money) thrown at it

... however... 

as Gordon (rightly) says-- none of the SGEs ever designed cooling for a 2.3L+ engine. They designed pretty much what they ended up with in the late 1930s for 1.3L cars with 7:1 compression (so they could burn kerosene or leftover lamp oil, apparently). Thinking that it could not be improved upon simply because the engineers who designed it were smarter than average ignores how progress works. There is no mechanical devise that cannot be made better. If late 1930s technology cannot be improved, then there has never been a more capable airplane than the Messerschmitt Bf 109.

I'm not saying that every EMPI piece of garbage shroud is better than what Herr Doktor came up with, but I am saying that there have been real improvements to basic parts of the platform-- especially to the oiling system since Rube Goldberg and his merry band designed the Type 1 oiling system eleventy billion years ago.

Hot rodding has given us a full-flow oiling system, external coolers, counterweighted crankshafts, and a whole host of improvements over what the SGEs decided to use 80+ years ago. I'm betting there are improvements to be had in the cooling department as well.

I'm a pretty big fan of the DTM.

Last edited by Stan Galat

Shoot.....   I think that the Type 3 pancake-style cooling is head and shoulders over the type 1, including the larger, post 1971 fan shroud version.  We don’t use it because it looks weird AND it needs the T-3 body wrapped around it to work well.

 It is especially effective because of the T-3 body changes made allow it to pull carburetor-only air in from the driver’s side louvers along the body (I’m thinking squareback, here) or behind the rear window on a notchback, and cooling fan only air from the passenger side.  Each side of louvers was larger than our 356 grill area, so there was twice the air pouring in to the car.   Then, there is some internal ducting design that serves to direct the air such that it accelerates the airflow the faster you go - A “ram scoop” as it were, but that’s all part of the T-3 body and something never seen on a 356, designed 30 years earlier.

I don’t see a lot wrong with the OEM T-1 fan system after 1971, but I see a whole lot wrong with the Speedster replica bodies trying to cool engines larger than 1776cc and many on here have learned not only how to live with those limitations but how to conquer them to make our cars far better than before.

I think the cooling systems on these engines is a big part of their draw as a hobby. I mean, just look at us!

It's a problem (or potential problem) that remains unsolved (or unsettled, anyway) and every person on this thread gets all excited trying to figure out the best approach. 

When I look at the cars on the Spyder forum—mostly running 2165s and larger—I see some bizarre looking cooling practices. Chutes and shunts abound; one guy has (had?) his remote oil cooler bracketed up by the twin grills with a fan trying to push air out—directly fighting DTM shroud fan which tries to draw air in. Clearly the Spyder body does not, by itself, make adequately cooling grumpy flat-4s an intuitive task. 

As a relative noob I intend to watch and learn, and see how the engine in my Spyder does with no external oil cooler. The Spyder guys had a damn conniption over this: You fool! No one goes without!

Reminder: mine is a Raby 1914 with a DTM and, afaik, stock to his 2007 specifications. I've built a full, louvered underpan to separate the exhaust pipes from the topside cooling and carb air intake, and am itching to get it underway and see how it works (or doesn't).

Given how my theories have panned out so far, I figure I have less than half a chance of being right about this. Hoping to get the oil temp gauge on the dash working properly sooner than later in this process.

Wow, I agree with Gordon, a beer sounds great right about now!  I’ve re-read this thread several times and what I know is I am getting a cooler.  One day, I may be able to add some value here, but an amazing learning curve thus far.  Thanks for all the input and I will let you know once this is completed and the results.  

Ed, it has been shown/proven that the twin grilles on a Spyder without an undertray EXHAUST hot air, not intake cool air. You know, with the old pieces of yarn taped on trick. Without an undertray, all cooling air comes from underneath.

I run a 96 plate cooler and fan because I have to. There is room for an internal cooler underneath the 911 shroud that I use. There is also no provision for flaps or thermostatic control of flaps for warmup. We end up with a pretty cold-blooded beast, but that ends up being OK when it's 75 ambient or above. It never overheats, not even on humid 95 degree days at Lime Rock Park.

Back to your regularly-scheduled early-IM-Speedster program......

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