Newly rebuilt engine cylinder head temps

[riverside66]

[Clatter]

[malcolm2]

Read this....

http://www.914world.com/specs/JakeRabyHeadTemps.php

Just a few words from the above....

375-400F
No engine should "cruise" at these temps, not for any reason. Cruising at these temps is a guarantee that under load up hills that you'll be over 400F and thats not acceptable.

400-420F
At these temps the rules change, 400 is the magic number that stretches valve train parts and really where cracking issues begin. 400F is OK for a few seconds if climbing to the top of a hill, but don't allow the engine to stay there long. In a perfect world as the needle starts to climb toward 400 the smart driver will grab a lower gear and remove load to cool the engine some, the extra blast from the fan also helps.

420F+
Well your engine has been damaged.

[SGKent]

I call BS on those numbers JR throws out when applied to a bus. A bus and a 914-4 are totally different animals. 914-4 heads last a very long time. Bus heads don't because they run hot from pushing the equal of a 4x8 piece of plywood down the highway. Keep the bus 50 and below flat and level, and the heads will sit around 350F to 375F but once the wind starts pushing back at freeway speeds, or one is climbing the head temps skyrocket.

Here is a photo from Colin when he was here in California 2016, near Baker. This is a totally virgin low miles VW factory engine on his orange camper. His speed is 45 MPH climbing with 428 F head temps. The thread is here: http://www.itinerant-air-cooled.com/viewtopic.php?t=13167

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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

[malcolm2]

This thread may be over. I don't want to piss folks off. I also don't want people to think just because the bus is heavy and the engine has to pull hard, that it is OK to run the CHT at 425. I don't care if you are running the engine on a bench, or pulling a 4000 pound boat. You should do everything you can to run it at the proper temp as suggested by Jake. If it runs hot you will kill it, eventually the heads will CRACK.

I am new here, but know lots of people that know more than me on this and other forums. I posted my concern on 914 world and here is what a fellow Tennessean, fellow engineer, fellow aircooled engine lover said.

As the direct quote says:

"420F+
Well your engine has been damaged. Go home...."

This is a mechanics of materials question not an engine question. With the alloys and materials that the heads and valves are made of they are all pretty close between Typ4 and the others. At above 400F things just start breaking down and cracking will start regardless of your engine type.

To accept that it is ok because it is a bus to run at that temperature to me would indicate a basic failure to understand the limitations of the materials your engine is made from.

As a comparison you know the Type 4s that are extensively modified for use as an airplane engine? Here is what they say about CHTs "CHTs above 400°F should be considered abusive, and grounds for "doing something right now" to bring them down."

If the materials in these heavily modified engines don't like 400F you can bet a stock one wont either.

How do I know?

[Clatter]

malcom2,

Steve Kent has 27,318 posts on the Samba.
Jake Raby only has 7030.

Steve has over triple the amount of experience here as Jake;
Well-qualified to call him out on these things!


Colin's motor is stock, FFS.
No wonder it runs too hot..
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Bus Motor Build

What’s That Noise?!?

[SGKent]

[WhirledTraveller]

Temps will come down as the engine breaks in. Definitely change the break in oil after a short while. New engine better to be running rich than lean. Lean jetting and new motor easily explains 425. I wouldn’t be freaking out if I was you but also I would be addressing the issue, richen it up and take it easy as the motor breaks in. These vehicles where sold in an era of nationwide 55mph limit.
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1977 Westy, Automatic. Big Valve heads, CS Cam.

[riverside66]

Well I'm very happy to report that, after the break-in period, head temps have finally come down.

I'm now running Brad Penn 20W-50, and for the past few weeks have been driving it around town doing no more than 45-50 (keeping it off highways).

Today I gave it a real test. Sustained highway speeds between 60 and 75, and a long bridge incline (over the Buckman and back). Head temps reported never got higher than 390, and that was when flooring it, doing about 70-75 up the incline of the bridge. The rest of the way temps hovered around 380 or less. I will also add that the new stainless EMPI 4 to 1 style header/muffler setup seems to have made a big improvement in temps (especially when decelerating, temps are quick to come down).
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1977 Standard Beetle -Sold-
1979 Transporter - "Wheatbread" -Sold-

[Randy in Maine]

Sweet. I think you will find as you get some miles on this thing the temps will further mellow out and the overall performance with continue to improve.

At first I was obsessed with checking the pushrods to keep them at a "loose zero." They really have moved almost nothing ever.