For those of you who have a digital head temp gauge, what's your #3 cylinder temp after a good distance of highway running? Say like after 20 minutes between 3K5 and 4K RPM in 5th gear, or in the 70-80mph range?

Part of the reason I got my car with a 2270 for a proverbial song was because the PO was having serious issues with the engine running hot and I think he was a bit fed up with the car. I've spent a crap ton of time tuning the shit out of the carbs and engine, and also replacing a few sketch-ball parts he had on there. I can now run EZ-PZ in the 310-320F range on #3 all day long off the highway, up to 60 or 65mph.
But once I get on the highway and get above 70mph, my temps start climbing up into the 370's and even higher if it's an uphill grade.
I know it's a much greater load on the engine to push through the air at that speed, but the difference in temps seems abnormal. Or is it?

I'm wondering if the 916 bumper on my car might have something to do with it. Is it possible that the lower "splitter" part of the bumper is acting like an air dam, preventing cool air from getting under the car, and causing the temps to go up at higher speed?

Any insight is much appreciated!

I would see 340 when I ran one. How are your oil temps behaving. IOW, does the oil temp follow suit or stay the same? Good luck; it's what keeps 'em running.
EDIT: More importantly, did you verify the accuracy of the gage and sender?

Oil temps are slightly higher after extended interstate running, but nothing that would be of concern. Only a few degrees.
I had a thought last night....I wonder if this could be due to the fact that I'm going 75mph with the top off and windows down. That's a hell of a lot of extra drag, which would create extra load for the engine. And that might explain the large change in head temps I'm seeing on and off the interstate.
I'm going to try a run today or tomorrow with the top on and windows up and see if there's any difference.

Do you have a wideband air/fuel gage as well?

I do. My AFR hangs out in the high 11's to mid 12's while cruising.

Well, you're definitely not "lean," so that's not causing it. Although referencing this thread: Type IV Temps, you're probably on the "high end" of acceptable and may need to assess some the cooling/tuning. Just curious, are you running an external oil cooler on your 2270?

Yeah I've got an external oil cooler with electric fans. The fans are thermostatically controlled, and the cooler is using the Tangerine external take off kit.

Yeah I've seen that chart. I'm just stumped as to why my temps are fantastic up to about 65mph, and then after I get on the interstate they go up. It's got to be something related to the speed, because otherwise they would be high all the time.

If you are detecting no ping (knock) when the temps read that high, I would suspect the temp sensor/gauge is not reading correctly.

Do you know what type of sensor & gauge you have?

Are you by chance running a lot of timing advance?

I don't think there's any knock, but I can't hear anything other than wind at 75mph with the top off and windows down!

It's an MGL Stratomaster Velocity 4 channel digital gauge. It's actually designed for aircraft use. I've got a sensor under each spark plug so I can monitor every cylinder.

Timing is 28 degrees BTDC.

so many things affect head temps, top down is one, there is extra drag( i noticed 3mpg drop with the top down), crosswinds are huge on head temps. Running high rpms ( like at 70-75) will raise them (as you know) but it also increases the wind resistance that the car has to overcome. that goes up by the square.

I don't think the 916 bumper is causing issues.

JMHO....you are too rich at those speeds. you have too much fuel that is still burning on the way out raising your EGT's and creating heat.

I'm finding that the "needs to be rich to stay cool" thing is not what people think it is.

you want to see 13.5-12.9 on the gauge while accelerating or climbing, 12.8-12.5 at WOT, and 16-17 while cruising, going downhill or decelerating.
Generally heads temps are 265-365 F
375 to 395 F is getting warm
405 F being too hot

Oil temperature
180 - 220 F is optimum
225 - 235 F is warm
235+ F is too hot.

I agree 12.5 to 13.5 at load and WOT, I aim for just under 13.
16-17 while at cruse is way too lean, 14 would be my max. In fact I see head temps rise the leaner it gets at cruse, I try to run at 13.5.
Decelerating, anytime the the throttle is closed no load (excluding idle) the reading is irrelevant.

Ed are you running both the external and stock oil coolers?

question,
sorry if a little OT , do you run the the stock cooling shroud system, if you do , can I ask
what kind of temp differences between the cylinders do you get ? thank you Bill D.

This is about what I'm seeing also. Although I like about 14.5, 14.7:1 at cruising. seems to give the best MAP reading so far. anything leaner makes the MAP readings go up.

Sorry. Did not read the referenced thread so sorry if this redundant.

First off I would say that the cooling airflow through the cooling shroud is driven by pressure differential. The air travels from areas of high pressure to low. The delta P is not large ( Evan with the fan helping). So any disturbance of the delta P can cause a significant change in flow through the system. It is a system - shroud, fan, cylinders, engine compartment, car underside etc. I suspect that #3 has some local stuff occurring that effects local airflow. Again it does not take much

Secondly 400 degrees is the consensus number for aluminum heads in the aircraft world.where such things are oft discussed. Anything below is good

There is much discussion in that world concerning CHT, mixture, timing, peak combustion pressure, AFR and particularly EGT. They are all closely inter dependent. If interested go to the Vans Airforce Website in the general discussion forum and search LOP. Lean of peak (EGT) operations is analogous to our cruise. Hours of informative reading there from some smart guys who work with these issues all of the time

I'm only running an external oil cooler. But with the tangerine remote kit, I have the block off piece which compensates the cooling airflow for there not being a stock oil cooler in place.

Yeah, I was running mid 12's to mid 13's AFR originally, but dropping it down to high 11's to mid 12's actually helped me run cooler head temps, which is why I took it down that low. While running mid 12's to mid 13's, I was in the 340F area around town. Dropping the AFR down brought my temps down to ~320F. Staying out of the 13's altogether really helped with my temps for driving around town.

At any rate, I just got back from a run down the interstate again, this time with the top on and the windows up. I was running consistently in the 350F range on even level grades, which I think is definitely acceptable. Ambient temps were about the same as yesterday when I had the top off.
I guess that drag from the open cabin really made that much difference.

#3 is always the hottest cylinder because it's the furthest away from the cooling fan. That's why that's the relevant cylinder to take readings from.

Yeah I've got the stock cooling setup. I'll have to look next time I'm driving to give you actual numbers. The gauge displays like a 4-channel bar graph and then you can choose which cylinder to specifically display a large number at the top of the gauge. I keep the number of #3 at the top since that's always the hottest.
At any rate, the bar graph looks kind of like a zig-zag with 1 and 3 being the hottest (3 being hotter than 1) and 2 and 4 being cooler. Makes sense since 2 and 4 are closer to the fan.

What weight oil?

Brad Penn 20w50

Personally, except for some full race situations, I wouldn't run an engine without a stock T4 cooler. The external cooler I'd only run on a thermostat controlled setup.

I've also never been a thick oil 20w50 fanboy, unless you live in an area of extreme heat, say constant 90*F+.
I use Delo 400 15w40

So do you think I'd be ok going back to just a stock oil cooler? That whole external setup that's on the car was the PO's doing. I'd be happy to go back to the stock cooler, and eliminate all the associated oil line spaghetti.

My external cooler is thermostatically controlled. The tangerine kit has a junction box thing that doesn't allow flow to the cooler until oil gets to 180* to speed up warm up time. I have a pair of fans on the cooler that are also thermostatically controlled.

I don't have a thermostat or flaps, so I think going back to the stock cooler, I'd have longer warm up times. I'd have to track down a set of flaps and a thermostat. Do you have to drop the engine to install the flaps?

With a 2056 and a more aggressive build cam and compression my symptoms are exactly the same, probably driven by the energetic so of air movement. My solution was to run rich, but not much if any more than you. I also have a remote cooler plus the stock. If I don't run high viscosity oil I get the green light when revs hit 600 at a stop light.
More airflow sounds like the ticket,if you can get it.

I've never had issues with my oil light coming on. Even after extended highway runs, my idle psi is around 20. Where does your external cooler tie in if you also have a stock cooler?

Yeah, more airflow would be the key. Not sure how to make that happen! I've tried running without the rain tray, and it has no affect whatsoever on head temps.

You need the flaps. Really. I bet you'll find that #3 and #4 CHTs improve when you install them. Even if you don't hook up the thermostat, the flaps are needed to direct air to the correct places.

--DD

Since you have ample oil pressure I would try a switch to 10-40 weight oil. This should drop your oil temps by 10 degrees or more and also have some positive effect on the head temp.

I'd read that before. Curious that one of the really well known engine builders among us that built my engine would leave them out. Unless the PO removed them for whatever reason, which honestly wouldn't surprise me. Can I install the flaps with the engine in the car?



Cool, I'll give it a try at the next oil change. I'd read so many posts from guys like Raby and others who recommend 20w50, so I went with it. But I know from my experience with classic cars that you have to do what the car wants, not what you want, so I'll give it a try and see if it helps my head temps at all.

Post #16 says the stock oil cooler has been removed using Foley's kit therefore it's normal that the flaps are missing. The stock oil cooler air supply duct should also have been blocked by this bent aluminum plate shown in the picture.

Click to view attachment

You said in the beginning that you don't have issues with oil temp but I couldn't find any data. What are those temps with your setup having only the external cooler and where is it located?

From what I have read from a known guru, oil temp and head temp usually behave separately.

Interesting thread as I eventually plan on building a 2270. FWIW my current 2056 DD behaves pretty much like your engine.

Yeah that's exactly what my setup looks like. This pic was from the PO, I assume when he was installing it. So you're saying that with the oil cooler take off kit I can't run the flaps? Even if they're just installed in the open position without a thermostat?
I obviously didn't install any of this, so I'm still learning the details of how this stuff got put on the car.
If I can't run the flaps with the external oil cooler, then that definitely makes me want to go back to a stock oil cooler setup and ditch the external one.

Oil temps are usually around 200 around town, give or take. They get a little higher after a while on the interstate, but not high enough to be of concern.

It sounds to me, from what Dave said, that my whole problem with head temps comes down to the fact that I don't have flaps.

Let's take a step back here. There are many ways to install a remote oil cooler and it is strongly recommended for any oversized engine. People in hot climate are also installing them on stock 2.0 engine if they tend to drive aggressively.

The easiest way is to put a sandwich adaptor with integrated thermostat between the engine and oil filter.

Click to view attachment

Or it can be setup in a full flow system where all of the pumped oil comes out of the engine and goes to a cooler via a thermostat.

Click to view attachment

The setup you have is another option developed by Chris Foley who is a very respected member here with a lot experience.

In the stock type 4 engine, a portion of the air going to the #3-4 cylinder bank is diverted to the stock oil cooler via the flaps. These flaps when connected to the cooling air thermostat will open or close managing the cooling air going over the cylinders and cylinder head. They will be closed at startup to allow engine to warm up. Once warm, they open and cool the engine.

Chris Foley's concept is to remove the stock oil cooler and use this portion of cooling air towards 3-4.

Since you don't seem to have any oil cooling issue, I don't see why you would want to do any modifications to you configuration. The flaps have been removed because they are not needed with CF's mod. It also means that you are 100% cooling your engine at startup which is something many of the CA people have been running for years. This cooling air thermostat was engineered for colder climates.

I hope this help in clarifying. I'm sure others will add what I've forgot...

I'm sorry, I did not realize that you had a setup that replaced the flaps. In that case, what you have is probably as close to optimal as we'll get at this point. If Chris designs and builds it, I'd put my trust in it.

If you didn't have the cover over the oil cooler location, then you'd have very significant problems...

And yes, we've had McMark (among others) post a difference from installing the flaps on a customer car.

You can install the flaps with the engine in the car. You need to remove the upper engine tin, which can be difficult to maneuver out (especially the left side; on my car the tin fouls on the dipstick tube and requires some gymnastics to unfoul it) and which requires removing a bunch of other stuff that's in the way, like intake and ignition and so on.

--DD

Ah ok I gotcha. I misunderstood, I didn't realize the block off plate replaces the function of the flaps. Ok, that all makes sense now. I mentioned the tangerine block off plate earlier in post #16, but I don't know if "block off plate" is what it's actually called.
Yeah I'm familiar with how the flaps work. This is my 2nd 914 and I've driven ACVW's for years. I just wasn't sure if I was getting optimal cooling, because I didn't install any of this stuff on this car and didn't have my hands on all the bits to know exactly how everything was hooked up. But it sounds like I am, so I'll definitely keep it then. This is the most modified air-cooled car I've owned. I pretty much know my way around these cars inside out when they're stock, but I'm still figuring out how some of these upgrade/mod parts work and integrate with the car.
So I guess there's really not much I can do about the higher highway head temps then, is there?

Officially the "block off plate" is the thick Aluminum billet plate that bolts on where the oil cooler used to be where the oil hoses plug in.

The flap that diverts the air that used to go over the cooler would be called something else. - "Cooler diverter cover"?

You mentioned that you have a 4 channels head temp gauge. It would be interesting to see data on the 4 locations as the purpose of Foley's design is to get more cooling on bank 3-4 which is partially deprived in a stock setup.

I think I remember reading in other posts temperature discrepancies among cylinders (stock cooling) in the range of 50 degrees or maybe event more. Others may have better data on this...

Aha, see I was using the wrong terminology! In my head that flap piece was "blocking off" the air from going the wrong direction.

Maybe we can get Chris to officially name it the "air flow diverter" or "air flow compensator"...or something along those lines



I'll get some data next time I'm out. It's supposed to rain here the next two days, so I won't be doing any driving until at least Tuesday

But I can tell you from the time I've spent with this car that tuning has a lot to do with the discrepancies between cylinders. The carbs were horribly out of tune and horribly out of sync when I got the car. Couple that with the fact that the PO had stuck two paper intake gaskets together, and was using that as his intake manifold gasket on the 3/4 side rather than the phenolic gasket (which was on the 1/2 side, btw ) and initially the 3/4 side was waaaay hotter than the 1/2 side. Before I touched anything on the car, I was hitting 380-390 on #3 cruising around town! No wonder the PO wanted to unload the car! Along with the car came a massive box of receipts, etc...and in there was also correspondence printed out between the PO and Chris Foley (there's a TON of Tangerine stuff on the car), where the PO is struggling with the head temps and was asking for advice. I think the PO just didn't know what to do.

But anyway, having taken care of all of those issue - proper phenolic gaskets on both sides, properly tune and balanced the carbs - the discrepancy is much less and my temps around town are fantastic now. It's just the highway temps that are the last piece of the puzzle for me on this car. But anyway, the bar graph on the gauge looks like an upward angled zig zag: starting with 1, then a downward zag to 2, then an upward zag to 3 (higher than 1), then a downward zag to 4 (higher than 2). So 3 is higher than 1 and 4 is higher than 2, and 4 is about in the area where 1 is...if that makes sense. Next time I'm out I'll toggle through each cylinder and get actual numbers.

My engine is just a tad smaller. 76 crank X 96 bore. My CHT runs between 325 and 350 under most circumstances (on my VDO gauge taken off the #3 spark plug). Of course just a bit hotter at high speed and climbing hills which is to be expected. Make sure ALL the holes, slots and openings in the cooling shroud are plugged. I also push the rubber gaskets around the spark plugs "inside" the holes of the cooling shroud so they seal up better when the shroud is pressurized by the cooling fan. Not unlike the baffling in an air cooled aircraft engine, it's very important that ALL the air that comes out of the cooling shroud is used to cool the engine. This is just my opinion but I think cooling fans on an oil cooler only serve to restrict the flow of air through the cooler.

I wouldn't worry about the head temps at high load conditions until they go past 395. As long as they recover relatively quick there is nothing wrong with the setup.
After timing and air/fuel tuning there isn't much more you can do to control head temps other than making sure the shroud is well sealed as Elliot said.

That's good to know! They do recover very quickly. As soon as I get off the interstate, it's back down into the 320's by the time I'm sitting at the stop at the end of the off ramp.

I guess I'm good then. A lot of worry about nothing!