Cross-over pipe question - preheat or not preheat, bus
- BellePlaine
- IAC Addict!
- Location: Minnesota
- Status: Offline
Cross-over pipe question - preheat or not preheat, bus
What is the difference between pipe J and pipe H? My fuel injected aircleaner has an open port that looks like it should have a hose attached to it; is that what pipe H is for?
I'm attempting to set up a stock muffler on my fuel injected 1974 engine with 1976 heater boxes in my 1975 bus.
1975 Riviera we call "Spider-Man"
- vwlover77
- IAC Addict!
- Location: North Canton, Ohio
- Status: Offline
Re: Exhaust question - Type IV bus
That extra piece on pipe H is an intake air pre-heater that was present in the early FI models and dropped in the later versions. If your air filter box has a large open port around 2 inches in diameter, that's probably what it's for.
Don
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78 Westy
71 Super Beetle Convertible Autostick
"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen
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78 Westy
71 Super Beetle Convertible Autostick
"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen
- Amskeptic
- IAC "Help Desk"
- Status: Offline
Re: Exhaust question - Type IV bus
It was insane complexity for no good reason. One day, the engineers woke up, slapped each other, "HANS! No need for intake preheating with injecktion!" And that's the truth.vwlover77 wrote:That extra piece on pipe H is an intake air pre-heater that was present in the early FI models and dropped in the later versions. If your air filter box has a large open port around 2 inches in diameter, that's probably what it's for.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
- BellePlaine
- IAC Addict!
- Location: Minnesota
- Status: Offline
Re: Exhaust question - Type IV bus
That's what I thought; that the H-pipe was related to the downward port on the air filter box. I just checked my spare (seized) engine and it still has the proper engine tin attached with the holes for the preheat hose. If Busted Bus has the H-pipe, and it's not killer expensive, I'm tempted to use it.
1975 Riviera we call "Spider-Man"
- BellePlaine
- IAC Addict!
- Location: Minnesota
- Status: Offline
Re: Exhaust question - Type IV bus
I gather that it's not necessary to use that preheat pipe for fuel injection, but it makes me wonder why the engineers designed it in the first place. Did they think that if it was good for carburation it would still be good for fuel injection? Any chance that using the preheater would make the engine run hotter? Do you think this is why they removed it?
1975 Riviera we call "Spider-Man"
- Amskeptic
- IAC "Help Desk"
- Status: Offline
Re: Exhaust question - Type IV bus
No, like every other preheater system, it shuts off via thermostatic valve in the air filter. It was only to keep fuel vaporized in the intake air stream. Injection does NOT REQUIRE such things with injectors adding fuel right at the intake valve!BellePlaine wrote:Any chance that using the preheater would make the engine run hotter? Do you think this is why they removed it?
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles