bus exhausts

regis101 · Post by **regis101** » Thu Dec 02, 2004 7:47 pm

Greetings. I have a 78 westy. It uses the 76-78 heater boxes and engine tins. I have a set of 72-75 heater boxes minus the tins. So they're just the pipes. If I change to the early style is there any additional tins that need to be. I am eliminating the stock/factory heat. I guess that the flappers at the bottom of the shroud should be held shut so as to push the air into the engine? I might be missing something there, though. Thanks

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Thu Dec 02, 2004 7:55 pm

Use the early boxes. They flow better and also seal better with less joints.

If you change them the only tins that you need to change are the ones that connect between the case and the heater box as they are different.

There are better headers out there for the 72-74 style as well. My favorite is the Thunderbird.

j-bro · Post by **j-bro** » Thu Dec 02, 2004 8:02 pm

I've never tried to swap heat exchangers and tin but I've worked on both kind and they look mighty different to me. I would guess that the wrong tin won't work. What I am really wondering is; why use heat exchangers and not heaters? If I wasn't using the heaters I would get a real header. The heat exchangers collect heat and hold it close to the head. Most heater control boxes have vents to let air flow through the exchangers without the heaters on. It is usually a disk shape on the back of the box or on some late buses a connection to some vent pipes. If you use heat exchangers and block off the air supply the exchangers will hold more heat and impair the ability of the heads to cool. A header on the other hand will help carry heat away from the head.

regis101 · Post by **regis101** » Thu Dec 02, 2004 8:12 pm

Don't think we're on the same page j-bro. One of the probs with da net. I want to eliminate the entire stock 78 exhaust. I have 72-75 down tubes. It's the header pipe that's inside the heater box/tin. Bolted to the flange in place of the stock 72-75 muffler will be an after market header and single quiet muffler. I am wondering if any miscellaenous under engine tins are needed or does the cylinder tins dump the hot air into the open. Now I'm not sure what I mean.

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Thu Dec 02, 2004 8:17 pm

Like I said, you ONLY need the 72-74 H/Es and the flaps to control the heat from them... Then you only need the tin that attaches from the H/E to the case from a 72-74 and then the correct Header for the 72-74..

Thats all. I do this all the time because we swap every engine for a Bus to the 72-74 style..

regis101 · Post by **regis101** » Thu Dec 02, 2004 9:24 pm

Your solution is crystal clear when using the entire heater box assembly so as to retain cabin heat. What if I gutted the 72-74 heater boxes so that just the header/manifold part remains. Not worried about factory heat.

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Thu Dec 02, 2004 9:56 pm

Thats quite a job. Those fins are cast aluminum..

The way I did it last was with a huge rosebud torch used to melt asphalt and burn brush.... Just melted it away..

Its a ton of work though..

Maybe I should see if Tiger is interested in copying the tubes inside the 411 heater box for us along with the flanges. The others that you can buy suck where they bolt to the head..

amskeptic · Post by **amskeptic** » Thu Dec 02, 2004 10:21 pm

regis101 wrote:Don't think we're on the same page j-bro. One of the probs with da net. I want to eliminate the entire stock 78 exhaust. I have 72-75 down tubes. It's the header pipe that's inside the heater box/tin. Bolted to the flange in place of the stock 72-75 muffler will be an after market header and single quiet muffler. I am wondering if any miscellaenous under engine tins are needed or does the cylinder tins dump the hot air into the open. Now I'm not sure what I mean.

The stock, fully-jacketed heat exchangers for the early Type 4 bus have a nice simple exhaust flow. The dedicated cooling air coming off the fan housing through those little flaps to the exchangers is not only to heat the cabin at your whim, but serves to draw heat from the cylinder heads as well. That's why VW went to such efforts to maintain air flow through the exchangers at all times, dump the hot air coming out of the closed downstream heater valves and later went so far as to duct that air to the rear of the car. You have stated that you want to "disable" the heating system, but are you aware that you are also disabling the engine's own cooling abilities during high ambient temperature conditions? As far as how the cooling air from the heads and barrels is directed by the lower tins, if you do have fully-jacketed early style exchangers, get the early style lower tins for sure, not only does it help remove hot air to the rear of the vehicle, but those tins also serve as pushrod tube rock guards, I've seen enough debris strikes against my nicely painted lower tins to keep them fitted, nice and tight, the factory way. What is the final word on the stock early style exchangers/muffler exhaust airflow anyway? It looks to be simple straightforward and effective. At what horsepower/rpm would that exhaust system be a detriment?
Colin

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Thu Dec 02, 2004 10:34 pm

I agree with Colin..

But.....
In 4 different instances I have seen head temps drop 10+ degrees with those lower tins removed....

I modified the ones on my bus to only be stone guards.

Post by **Piledriver** » Fri Dec 03, 2004 12:39 am

`78s had squareport heads...
If yours is as original, it's NOT an easy swap.

As Jake has said before, even if you DON'T hook up hoses or HX, let those outlets flow free... IIRC, Jake has data that showed higher head temps with them blocked off due to cavitating the fan or some such.

Wally · Post by **Wally** » Fri Dec 03, 2004 2:19 am

MASSIVE TYPE IV wrote: Maybe I should see if Tiger is interested in copying the tubes inside the 411 heater box for us along with the flanges. The others that you can buy suck where they bolt to the head..

Please do!
An even better flowing new 411 heater box would be awesome! Most of the 411 boxes have severe rust on the pipes/flanges themselves, but often only little or non to the tin surrounding the tubes, because of former oil sweats from the valve covers.
Then you would be able to use the 411 pipes as is for non-heater applications and wrap you existing 411 sheet metal around it for heater application!

Stock inside diameter of the 411 box is 33mm IIRC. Making them 39mm would be ideal IMO and would complement the BAS 4 into 1 collector (the one that normally bolts to heat exchangers) nicely as that one is 39mm inside as well

Thanks,
Walter

Volcano · Post by **Volcano** » Fri Dec 03, 2004 3:14 am

Jake,I'd love to see Tiger make the j-tubes.Hopefully for both head styles.I also took off all the aluminium from the stock heaters.I won't do that bitching job again.Roger

raygreenwood · Post by **raygreenwood** » Fri Dec 03, 2004 9:11 am

There are two different diameters for 411/412 heater boxes. memory is failing me today...but one is larger.

Jake...so on the flat cover plates on teh early bus/411 sheet metal....would you suggest...say...perforating them to allow some stone gauard function yet...allow air to escape? Ray

regis101 · Post by **regis101** » Fri Dec 03, 2004 2:17 pm

... No. I don't know the whole/real deal. This is why I am asking. The donor head pipes I have were in the back of an early bay bus at the junkyard. They are nice round straight tubes. No internal aluminum baffling, per se,. Maybe these are 411's and I dont know it? The tin around them were half gone but they looked as if they would belong on a bus. Once again, my lack of VW master knowledge eludes me to know if the 411 style heater boxes were designed to be friendly in the busses as well. Point is I have a nice set of head pipes with out any tin attached. Would like to use them if I could. I do understand that the entire cooling system would be better if left intact. Don't know how important the heater boxes themselves are to remove heat from the engine. My only real knowledge, sad to say, is the magazine pictures of the underside of vehicles that show open pipes right off the head(s). A full header system. Heck, the proto-type bug/T-4 header on Aircooled's forum shows the header at the head port with no tins that I see. What the heck am I missin' here...

Post by **Piledriver** » Fri Dec 03, 2004 3:49 pm

Busses equipped with gas heaters (sometimes? always?) had those tubes wtihout the big cast alumunum fins/etc.

The main thing is LOOK AT THE FLANGES ATTACHED TO THE HEADS.

The square ports and ovals look quite different... It should be obvious.
They are NOT interchangable.