Fuel System: Difference between revisions
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The bus runs on LPG. Current hardware is stock naturally-aspirated: a single Impco CA425 mixer on a cast-style mount, single Model E vaporizer. '''Neither is adequate for the blower build.''' | The bus runs on LPG. Current hardware is stock naturally-aspirated: a single Impco CA425 mixer on a cast-style mount, single Model E vaporizer. '''Neither is adequate for the blower build.''' | ||
=== Tank Specifications === | |||
{| class="wikitable" | |||
|- | |||
! Field !! Value !! Notes | |||
|- | |||
| Manufacturer || <code>BRUNNER ENG. & MFG. CO.</code> || Bedford, Indiana | |||
|- | |||
| Capacity || <code>80.8 GAL</code> || Water capacity (W.C.) | |||
|- | |||
| Serial Number || <code>AF5255</code> || | |||
|- | |||
| Manufacture Year || <code>1982</code> || | |||
|- | |||
| Max Working Pressure || <code>312</code> psi || | |||
|- | |||
| Service Temperature || <code>450°F</code> || | |||
|- | |||
| Tare Weight || <code>324.32</code> lbs || | |||
|- | |||
| Outer Diameter || <code>18.0 in</code> || | |||
|- | |||
| Length || <code>77 in</code> || | |||
|- | |||
| Head Thickness || <code>.187 in</code> || | |||
|- | |||
| Application || <code>FOR LP GAS ONLY</code> || | |||
|} | |||
'''Note:''' The tank is rated for "Above Ground Only." This is standard for many older LP tanks; it does not preclude installation, but the mounting must support the full weight and allow for thermal expansion. | |||
=== Factory vs. conversion === | === Factory vs. conversion === | ||
Revision as of 07:32, 30 October 2026
Fuel System
| Status | LPG confirmed. Factory vs. conversion unverified — pending Marti deluxe report. Blower fuel spec open. |
Overview
The bus runs on LPG. Current hardware is stock naturally-aspirated: a single Impco CA425 mixer on a cast-style mount, single Model E vaporizer. Neither is adequate for the blower build.
Tank Specifications
| Field | Value | Notes |
|---|---|---|
| Manufacturer | BRUNNER ENG. & MFG. CO. |
Bedford, Indiana |
| Capacity | 80.8 GAL |
Water capacity (W.C.) |
| Serial Number | AF5255 |
|
| Manufacture Year | 1982 |
|
| Max Working Pressure | 312 psi |
|
| Service Temperature | 450°F |
|
| Tare Weight | 324.32 lbs |
|
| Outer Diameter | 18.0 in |
|
| Length | 77 in |
|
| Head Thickness | .187 in |
|
| Application | FOR LP GAS ONLY |
Note: The tank is rated for "Above Ground Only." This is standard for many older LP tanks; it does not preclude installation, but the mounting must support the full weight and allow for thermal expansion.
Factory vs. conversion
Believed factory or ship-through — unverified.
Supporting evidence:
- Cast-style mixer mount, no obvious aftermarket adapter plate
- DSO special order tag (
DSO 74 / SO 3152) — see Chassis Documentation - Fleet options (traction sanders, tow hooks) consistent with a municipal/district order
Do not log as fact until the Marti invoice confirms. If it shows a ship-through or upfitter conversion, log as "factory-ordered LPG conversion" and cite the line.
Current hardware
| Component | Current | Adequate for boost? |
|---|---|---|
| Mixer | Impco CA425 (single) | No — sized for NA |
| Vaporizer | Impco Model E (single) | No — will starve and ice |
| Lockoff | Unknown — inspect | Unknown — must be sized for combined flow |
| Tank | Unknown — inspect and record | Unknown |
| Plumbing | Unknown — inspect and record | Unknown |
Blower fuel plan
- Dual Model E vaporizers, boost-referenced. One E cannot vaporize the airflow at target power; a starved vaporizer ices, pressure collapses, and the engine goes lean under load.
- Reference both E's to manifold pressure from a common source with equal-length lines — not two separate taps, or the units fight and deliver unevenly.
- Parallel liquid feed from a common supply with a shared lockoff rated for combined flow. A single-E lockoff becomes the bottleneck.
- Parallel coolant feed off the heater circuit, split so the rear unit is not downstream of the front unit's heat load. Marginal coolant flow ices a correctly-sized vaporizer.
- Dual mixers into a common plenum with a fabricated dual-plate adapter. A single CA425 chokes a blown big block — rich at idle, lean at load.
- Mixer sizing is driven by airflow at target boost. Specify with the shop, not by guesswork.
Open items
- Tank size, mounting, and liquid-vs-vapor withdrawal — inspect and record
- Lockoff model and line size — inspect and record
- Whether the current mixer mount is a bolt-on or fabrication pattern for the new adapter
- Factory vs. conversion — Marti deluxe
- Compression and cam — shop measures before boost selection; LPG engines run higher static compression than gasoline, do not assume gasoline figures
Safety and inspection notes
- Bag the mixer throat and vaporizer before any pressure washing.
- Photograph the mixer mount from multiple angles before disturbing it — it is evidence for the factory question.
- Record the existing single E and CA425 as spares or patterns; neither goes back on a blown engine.
Documentation
Photos filed: mixer and mount, vaporizer, lockoff (pending), tank and plumbing (pending).