To EGR or not to EGR? Stock 2.0L Type IV

[VWLover77]

'78 Westy with stock Type IV 2.0L, hydraulic lifters, Hoffman Blueprint Special heads, L-Jet, Dakota Digital CHT gauge, Innovate Motorsports AFR gauge.
All cooling tin, flaps, and foam seal in place, with a working thermostat.
100% stock exhaust including cat.

Some may remember from previous posts that I struggled last summer and Fall trying to get 65mph head temperatures under 400 degrees on this freshly rebuilt engine (now with about 3K miles on it). Reduced distributor advance (now around 26 deg max mechanical advance) and richer mixture (around 13 at flat 65mph cruise and 11.8 at full throttle) have yielded little to no improvement.

The EGR system was completely missing from this Bus when I bought it - the EGR valve holes are all plugged at the plenum.

Would reinstalling an EGR system provide any potential benefit?
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Don

1978 Westy
1971 Super Beetle Convertible


"If more of us valued food and cheer and song above hoarded gold, it would be a merrier world." - J.R.R. Tolkien

[SGKent]

a little but good luck finding good parts. The mechanical EGR valves have been NLA for 30 years, and no one builds quality replacement parts other than the gaskets. Mine works and is like new, but I am in California where it is required on 1976 and later buses.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[timvw7476]

don't know if you're in an emissions exemption zone but the cat, or at least running with a test-pipe instead, would be the first thing to try as far as getting it to run cooler.

[VWLover77]

I tried the test pipe in place of the cat last summer - no difference.
_________________
Don

1978 Westy
1971 Super Beetle Convertible


"If more of us valued food and cheer and song above hoarded gold, it would be a merrier world." - J.R.R. Tolkien

[SGKent]

Getting under 400 F on a 2L engine is pretty hard if that is the ultimate goal. Keeping it below 450 F is certainly doable. The spark plug senders are in the hottest part of the head, and the plug itself conducts heat. I don't use a sealing ring on the plug with the sender, and let the sender act as the sealing washer. Sealing washers are beveled and they oval out the sender, allowing a little combustion gas to leak out, raising the sender temp. I'd consider putting the timing back to about 28 - 29 BTDC. Your mixture range is fine. If you go leaner the temp will go up then about 16:1 it will start going back down but you will be pushing more heat into the exhaust ports because the burn will be slower than at 14.7. Around 17:1 the head temps will fall a lot because there is less gas to burn, but exhaust temps go up because the burn is so late more of it goes into the exhaust. I have EGR and my head temps are similar to yours. My bus passes smog cleanly.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Alan Brase]

I've become convinced it may be a help. Just a pattern I've noticed since buying my first bus in 1982:
These USUALLY served the first owner pretty good, perhaps lastin 100-120k miles. The somebody takes it apart, does a nice rebuild, and then the thing has hot heads problems from then on. Terminal problems, often. And in nearly every case, the EGR was removed, because, well: smog stuff, who needs it!
I will soon be resurrecting my 1980 Vanagon, built June, 1979, 49 state.
By god, I'm gonna put the EGR back on. Just bought a new repop filter. Found a good original 4 into one exhaust pipe with EGR connections.
We'll see.
_________________
Al Brase
Projects: 67 sunroof bug, 67 Porsche 912 Targa, 70 Westy
Dec 1955 Single Cab pickup WANT 15" BUS RIMS dated 8/55, thru 12/55
To New owners: 1969 doublecab, 1971 Dormobile
Vanagons:
80 P27 Westy JUL 1979, 3rd oldest known US
83 1.6TD Vanagon, 87 Wolfie Westy daily driver, swap meet home

[SGKent]

even the unmolested low mile 2L buses garage finds run those +400F temps.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Balidas]

You could look into ceramic coating your exhaust system. That could help lowering radiant heat and affecting your temperatures.

[metahacker]

11.8 - 13.0 is ideal
if you are running E10 your Lambda 1.0 is 14.13 AFR
so 11.8 is your ideal AFR
for light throttle as lean as 13.0 is ok

alternatively, tuning for 16-17 yes you can lower engine temps quite a bit (as SGKent said), but it's very difficult to set this tune up on Jetronic (and really should be done with a 123 distributor, since you will need lots of vacuum advance to make it work). in my experience i needed the EGR to "help" me get 17:1 cruise. the results were interesting (the engine definitely ran very very cool). but if i was shy on ignition advance for high vacuum, it would stutter. other than that, it was pretty awesome. although, it seemed a bit challenging to tune it perfectly and not compromise on idle quality with an automatic.

generally speaking, IMO, the EGR is not going to help you, it's just bad news IMO...except for lowering NOx. yes, in theory it could make it 'cooler' by dynamically reducing displacement..... but in practice i don't believe that has been observed for normal driving operation.

are you concerned about your highway temperatures?

you may benefit from an external oil cooler.....one that is ducted for high pressure cooling highway speed, not a stupid one with an electric fan (you already have one with a mechanical fan on your engine now). e.g. the opposite of what 99% of people are running for their external oil coolers

high rpm will give you high oil temp (although high rpm also means high fan speed, which is good), and highway cruising is sustained high rpm... it is also sustained high pressure air under your car, waiting to be directed through your oil cooler...... i run an oil cooler as described (sealed/ducted to force air in from the air stream underneath) and i like what it does for my bus under these conditions... and i do sustained 70-85 for hours and hours... the oil cooler may help a little bit...but ultimately, once your AFR and timing are correct, the CHT is mostly a product of your engine configuration (e.g. compression cam etc), and fan speed aka gearing vs the load of pushing a bus the engine is too weak for.

also you might think im a loon for saying this, but putting MMO in your gas every fill up can lower CHT. i know someone who rents a fleet of buses and tested this using the current production MMO "automatic oiler" for the intake system...and according to him his A/B testing demonstrated that it was saving engines in his rental buses .... since you are in testing/data collection mode, would be curious to hear your results if you try it either way, i've put 4oz in with every full tank...and daily drive flat-out

[SGKent]

the other alternative that I did not mention because the bus engine is already built is to have the inside of the heads, and the piston tops ceramic coated with a special ceramic that slows heat transfer. It improves engine efficiency and is the only thing I know that truly lowers head temps. It will also lower oil temps and allow a thinner oil to be used in hot weather. Len Hoffman does this type work on AMC heads. He will not work on used German VW bus heads.

example from air cooled technology

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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[VWLover77]

[SGKent]

it cannot leak in either position, open or close. It will bypass inbetween. The diaphragm cannot leak.

closed at idle - cannot leak
closed at WOT - cannot leak
works between the two

Diaphragm cannot leak
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Amskeptic]

[VWLover77]

[SGKent]

Don it does a little. Part of what it does is lower the risk of detonation.

Think of fuel molecules like a little packet of energy, like a small balloon full of fuel waiting to burn as they sit there surrounded by the oxygen. When the spark occurs it lights off those near the spark. As they burn they set the fuel next to them on fire, which sets the next on fire etc.. As that happens the pressure in the cylinder goes up. If it goes up too high it is like a diesel, those fuel packets ignite simply from the heat and compression, so all the remaining fuel packets go off at the same time creating an explosion. This is bad for the engine and is like a hammer hitting it when it happens over and over. When the mixture is richer there are many more fuel packets than air, so they absorb some of the energy before they can burn, they have to wait for an oxygen molecule to snuggle up to them. One way of lowering that risk of explosion is to lower the compression in the engine. That puts the molecules farther apart, and lowers internal temperatures. But it also lowers efficiency and power, that is another lesson. What the EGR does is allow inert oxygenless gas to be sent into the mixture, thus keeping the compression up for efficiency and power, but keeping those fuel packets farther from an oxygen molecule. This is like lowering the compression so the temperature is lowered - but it really isn't. At idle those inert gases would make it hard for the engine to idle. And at full throttle you need all the power. So, it only operates at part throttle, which will help keep your engine a few degrees cooler but more importantly reduce the chance that the mixture will blow up all at once and detonate - being like a hammer on the inside of the engine.

To make it work, you will have to be sure that the carbon is cleaned out of the tube the EGR dumps into inside the plenum. It distributes the inert gases evenly into the cylinders. There is also a small hole in one of the gaskets, It is smaller on California buses with catalytic converters than Federal buses without cats.

Also - when you go down the highway, the bus is a load on the engine. Air, drag, weight etc., all combine to put a load on the bus. It takes X energy to move the bus. When you add the EGR you lose a little power so to maintain the same speed you are fractionally pushing the throttle more. You aren't burning more fuel, you are burning essentially the same as what you would have with out the EGR. That gives you the X energy to move the bus at the same speed. The heat output is the same because you are offering the engine more air and fuel to maintain the same speed. Since the FI monitors air and fuel, the efficiency remains about the same. The fuel molecules are now partially surrounded by inert gas so they burn slower, again lowering temperature for each molecule but there are more of them. That lowers NOX and helps prevent detonation. Think of it like hiring 15 weak people to do the job a crew of 10 strong people used to do. If you pay each person less your payroll can be the same, and the 15 can get the same work done as the strong crew, but each person now is doing less work. Each person is putting out less energy but the overall amount of energy being used is the same.
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Clatter]

FWIW the ‘75-‘79 exhaust with the short f-pipes isn’t known to be efficient at moving the hot exhaust out of the motor.
A set of ‘72-‘74 heater boxes and a T-bird would likely make it run cooler.

After that, a cam with more duration, especially on the exhaust side, would help.

Supposedly VW was making these motors run hotter on purpose for emissions reasons at the time..
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Bus Motor Build

What’s That Noise?!?

[SGKent]