Intake Air Temp Questions AHU into '78 Bus

redcorradoguy

Veteran Member
Joined
Jun 4, 2005
Location
Manhattan, KS
TDI
2002 Golf TDI, '78 Bus with '98 AHU
I've got a '78 Bus with AHU installed. Runs pretty well, though the IATs are quite a bit higher than, say, in my Golf. Not uncommon to see close to 180 degrees at times of high boost for a little while.

I'm currently running a watercooled intercooler with a too-small radiator (because I wanted it to fit on the front suspension).

But under normal circumstances it works "Ok, I guess"but I have wondered recently about going back to the air to air intercooler because it did just about as well and would be a lot simpler of a system.

I had issues on a recent trip with hoses popping off because I decided I'd use clear reinforced vinyl hoses instead of rubber, so I could see air bubbles. Bad idea-as the vinyl heated up it started popping off connections.

I made it to the camp spot and changed to all rubber hoses and didn't have any more problems, but did wonder along the way...

What would have happened, if anything, if I kept driving with no water in the system. The couple times that the system drained, I saw intake temps get up to well over 200 degrees, maybe 230 or possibly more.

So the, now mostly theoretical, question is, if the engine coolant temps stay in check, and the EGTs stay in check, would those super-high intake temps hurt anything? Maybe not forever, but how about over a few hours so I wouldn't have had to show up to camp as late?
 

ToddA1

Top Post Dawg
Joined
Aug 3, 2011
Location
NJ 08002
TDI
'96 B4V, '97 B4 (sold), '97 Jetta (scrapped)
Personally, I'd think it'd run like a non-intercooled system and you'd just be down on power.

The pump wouldn't like it, but I'm sure that's easy enough to disconnect.

-Todd
 

redcorradoguy

Veteran Member
Joined
Jun 4, 2005
Location
Manhattan, KS
TDI
2002 Golf TDI, '78 Bus with '98 AHU
Sort of what I was thinking but I was nervous to do it. While the current engine is running well and marched the Bus up an down mountains, I've been bitten by a couple blowing up. Even though two of the three failures were from easily identifiable causes (loss of coolant before I got a low level sensor working finally) I'm still gunshy.

I knew that lower intake temps will lead to lower EGTs and too-high EGTs are very problematic, and I knew that higher intake temps result in less air available and therefore less power, I was unsure of if there were any other potential consequences. I was aware of the older turbo diesels not having intercoolers at all, though I don't know how different the rest of the motor is with regards to if any damage could happen.

Sounds like I could have made it to the campsite more quickly if I had just unplugged the pump and stopped messing with it! Oh well.

Does make me feel better about the (un)necessity of messing with the intercooler system at this point.

Still very interested in other's thoughts/opinions on the subject.
 
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markd89

Veteran Member
Joined
Oct 21, 2009
Location
Los Angeles
TDI
1978 VW Bus 1Z TDI
IMO - you went through the hard parts of getting the TDI into the bus, why not a little more work and get it dialed in nicer with better IATs, you'll have more power, less EGTs also less load on the cooling system.

Answering the question you didn't ask (since I have a 78 Bus with IATs at ambient +20F).

1. What I didn't do: Huge A2A IC mounted flat under left side of bus. Even with long tubing, this has proven itself in a Vanagon application. Emphasis on huge.

2. What I did: Two A2A ICs in series ($90 ones from frozenboost.com). One radiator 12x24x1" under the bus angled to catch the air. My setup works, I just like the idea of #1 as less parts, less weight and better outcomes.
 
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