engine deck height on 78 bus

[raygreenwood]

Agree with WT.....you can probably get away with a head gasket of .030". Then check with play-doh with the heads on and valves moving yo make sure you have no interference....and you shouldn't.

As for compression and tight deck...aslo agree with WT. A slight rise in compression will do the 2.0 just fine....especially if its done with a tight deck and not a small combustion chamber.

Vw set the compression at 7.3 back in the mid to late 70s. Fuel quality sucked.....tires were less efficient in rolling.....and part of that was done for reduced NOX emissions. If you are not somehwere where NOX emissions are critical....an extra 0.2 or even up to 0.4 compression increase will be just fine. Ray

[Wildthings]

[raygreenwood]

[SGKent]

Guys - Mike you lived at altitude, and Ray you have never owned a bus. Running 8:1 on a 2.0L bay with today's alcohol based fuels will cook it. especially with used heads. That is just how it is. Gene Berg was well respected in AC VW's. He suggested even lower for all air cooled VW engines except racing ones. The only issue with that is that bays are already under powered and there is just a trade off which 7.3:1 is barely acceptable due to the heat. At 7.3:1 my heads on a 2L are at 405 - 415 F at 65 mph. My 1971 1600 at 8.5:1 never approached that. 350 F was normal day and night around the clock with that engine. The cooling system on a 2L was designed for a 1700 engine. It can't handle the heat. You never hear of a 2L bus that died because it was too cold.

[raygreenwood]

[SGKent]

OP - consider not running a .030" shim. If you do your next post may be how do I cool my motor down and stop the piston scuffing.

in 1991 VW added a .030" shim to the base of their cylinders and removed the head gasket only because they were dealing with heads that were new and had stock combustion chambers. They also added notches to the rods and increased piston to cylinder clearances to stop scuffing and seizing. If you increase the C/R you only move back towards that seizing and scuffing. Your heads are fly cut and no longer have the stock combustion chambers. The .030" shim in the VW TSB is for stock heads that have not been fly cut. I am also guessing that your case has been cut a little too, or the cylinder area of the case has collapsed a little. You have to use whatever it takes to get the C/R down.

Here is that 1991 TSB retroactive on all 2L Bays and Vanagon engines.

https://kentcomputer.com/77VW/techbull.pdf

[Wildthings]

[SGKent]

Doesn't 100% of the heat that isn't used for mechanical work either go out the tailpipe or somewhere out via one kind of cooling or another, radiation etc.? Wouldn't you rather have the heat going out the top large iron cooling fin than into the aluminum head, and aluminum piston, or soaking the valve and guide on its way out the exhaust? I am trying to get max cooling cause the engineer screwed up there instead of making HP. If the engineers got the cooling right we'd be making 120 HP on these T4 engines from the factory. But then again they were designed as slow speed utility trucks and people carriers, not freeway fliers.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[timvw7476]

^^^^^This goes hand in hand with catalytic converters from mid70s.
maybe VW had an emissions reason to pack more heat in their 2.0s.
didn't even consider us 21st century operators back then.
EDIT: VW needed more heat to keep the cat cooking & tuned the 2.0
to do just that, almost all the time.

[SGKent]

they added the afterburner loops and F-pipes - lengthening the exhaust to improve torque and burn CO / HC's. The leaner mixtures kept the heat up. By 1979 when they were forced to go to 14.7:1 on California cars they had to add flanges to the exhaust and move the heater boxes back near the heads to help cool the heads. At that time they told the public they were done with air cooled engines beyond the first year or two Vanagons. CARB and EPA made it too costly to continue. Water cooled engines can be produced and managed as to emissions much cheaper. They also last longer and it was clear that the Europeans were going to need more power to keep up with American cars and "vans." Anyone 60 yrs to 70 yrs old (like me) remembers the way the public just went head over heels for the big American vans with V8's. They could pull boats, climb mountain passes on freeways quickly - and they had more room. VW got the max they could get out of the air cooled motors with the Porsche 6's. They were the descendants of the fighter aircraft of WWii before they went water cooled or into the private plane market - Continental, Lycombing etc. Now we are left to argue why Herman, Otto, and Peter designed things like they did or chose the C/R that they did. And yes - they had no thoughts what so ever we might be doing in 2018, some 40 years later. They are mostly gone since they were probably in their late 40's and early 50's when they designed these buses. The guys my age were still sharpening pencils for them and making copies of their work for the factory to follow.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin