Need input from IM owners

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.

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

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. 

A pool noodle is a quick and dirty way of temporarily holding the decklid open.

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.  

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. 

@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. 

@Sacto Mitch posted:

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

 

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

Thanks all for the input and Gordon for kicking it off.  I will try the noodle pool trick,  it will look into the coolers for now 100%.  Still 70 in New England, but will change quickly!

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.

@Gordon Nichols posted:

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.

Stan, I agree with your sentiment.  I do not want to worry about this as temps rise here.  

@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. 

I agree that external oil coolers are probably a necessity for most of our cars.  Properly placed, and having a cooling fan, helps a lot.