LPG

[JezWest]

Not that I am actually thinking of doing so, but I wondered if anyone had converted a 'high performance' motor to run on LPG?

This is what made me think of this, DRLA LPG adapters - http://www.ebay.co.uk/itm/Dellorto-DRLA-LPG-adapter-/330652888889?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4cfc72af39#ht_500wt_949

Just for the sake of argument, assume this combo (which is my current motor)..

1776cc

Carbs      DRLA 40, 200 air, 150 main, 55 idle, 34 vents, 33 pumps, 9164.1 emulsion, 'jet doctor'ed idle jets
Heads   Fumio Fukaya 40 x 35.5
Cam      Engle 120
Exhaust   1 5/8 merged with Mondo muffler, wrapped, ally heat shields like Hot VWs did
Fuel      CB Performance fuel pump and Holley regulator (set to 3 psi)
Ignition   Flame Thrower coil, Mallory Unilite with grey springs, 24 deg advance with 8 deg static, Taylor .409 wires, NGK BP7ES plugs

Have to do things to the fuel tank/pump/lines/regulator/carbs, but anything else..? I guess something would need doing with the fuel filler - either replacing the stock one on the quarter panel or swapping for a tank with a filler right on it like older bugs.


Of course if I could figure out how to grow oranges in Blighty or something else maybe I could knock up an allotment biofuel plant in my shed. How hard can it be?

[Jesse Wens]

I did a turbo one already and the new longblock is gonna be run just like your sugesting next summer in and around belgium.
The year after it will be turbod too, gonna be a wild ride.

[GreenTom]

That's very easy thing. LPG is very popular in Poland. I have it in 3 of my cars. soon I'm converting my 2.1 DJ to 2xDHLA + the same kit as you posted but brand new.
a lot of people in "Europe" think that LPG makes more power than petrol... unfortunetly it doesn't. No metter how good the system is the engine makes less power and thaes more fuel (LPG).
for example:
- 1200 mexico + LPG - about 8,5-10l of LPG for 100km
- 1600 DP + LPG - about 9-11l of LPG  for 100km
- 2,1 DJ in my tye 25 - 275km on 31l of LPG (using LPG from Germany) and 220-230km on 31l of LPG using Polish LPG. (9-11l of petrol for 100km)
- 1,6 SPI opel Astra 9-11l of LPG for 100km.
eaven though it's much cheeper than petrol

[Bruce]

With that conversion piece, can you still use petrol if need be?

[GreenTom]

With that conversion piece, can you still use petrol if need be?

Yes.

If using typical old generation "gravity system" for carburetors and simple mechanic FI or old FI (not EFI) you've got a "panel" with 3 position switches:
- Only petrol
- Nothing (this one shots down petrol solenoid but doesn't turn on LPG so petrol from bowl can be burnt).
- LPG

You just switch on LPG hen ever you want to.
With new generation LPG systems for EFI you have switch position that is petrol + LPG. Car starts on petrol and when it reaches certain RPMs (also proper temperature of coolant) it switch to LPG on his own.

LPG is good thing if you use car for everyday to lower costs of driving around, But I wouldn't use it in my bug for racing... just makes less power ads might to the car (whole system with bottle and stuff weights over 20kg...)
 Depends on capacity of the bottle).

I spotted that LPG systems in Europe especially in UK are so expensive comparing to prices of genuine Italian proper gear being assembled in Poland.

So if you need LPG in a beetle, bug, KG, typ25 just bring

[jaqo]

But I wouldn't use it in my bug for racing... just makes less power

That's not true. It's possible to make good (the same for sure) power out of it but it's difficult and expensive to build and tune a system like this, that's why most LPG system installers can't do that. It's not good for racing because of the weight, complexity of the system, cost of a good one (that allows you to make good power) and reliability issues. Other fact is that LPG is not allowed in many racing disciplines. LP
Installing a system like this for a bug isn't economically logic, and doing it in Poland  where 99% of workshops installing it don't know what they're doing is a bad idea, and there are many more reasons why it's a bad idea for a beetle. You need a dyno and a lot of experience to do it right.
Daily driver driven A LOT - sure, otherwise forget about it.

[hotrodsurplus]

LPG has great power potential--far more than pump gasoline. You just have to change a few things on an engine built for gasoline to make it operate to its potential on LPG. This will get long.

We often measure the energy in fuel by British Thermal Units (BTU) per gallon. Gasoline has about 110,000 BTU/gallon. LPG has about 85,000 BTU/gallon. So yes, LPG has less energy per unit measurement but that does not mean it is inherently bad for performance. Methanol, the alcohol used in racing, has only 55,000 BTU/gallon but nobody ever accused it of being a poor choice for racing fuel.

Methanol and LPG fuels are less efficient than gasoline so the engine's efficiency must be increased to compensate. The best way is to increase an engine's efficiency is to increase its  compression ratio. That's where methanol and LPG shine. We express a fuel's ability to resist pre-ignition by its octane rating or equivalent. The highest common rating in Europe is 98 RON which is roughly equivalent to 93 AKI in the US (for the Beetle VW specified 91 RON, which is about 87 AKI in the US, so anyone who thinks stock VWs run on super unleaded is misinformed).

The octane-equivalent figure for LPG is about 112 to 114 (or roughly 108 to 110 by AKI standard in the US). That means LPG will resist pre-ignition to a far greater degree than pump gasoline can. If an engine operated properly at 9:1 static CR on premium pump gas then it may operate best at maybe 12:1 or 13:1 static CR on LPG. Methanol-fueled racing engines frequently run about 16:1 depending on cam timing.

So increasing the engine's efficiency may regain most of the fuel efficiency lost by going to LPG In doing so, the engine will pick up considerably more power than it had with pump gasoline. Unfortunately LPG tends to burn at a slower rate than gasoline but that can be addressed by altering the ignition timing settings. But then again the reduction in combustion chamber volume may be sufficient to compensate for the slower burn.

LPG is generally regarded as burning softer than gasoline. It also burns a lot cleaner, and even if the compression ratio is increased it tends to burn cooler. All are advantages in any engine but the heat advantage is especially welcome in an air-cooled VW. It's common for oil to remain clear for thousands of miles of service. LPG simply doesn't litter the engine with carbon.

From what I understand, the dual-fuel systems don't operate to the same potential as LPG-only systems. But they can be made to work with common conversion mixers (Impco and Century are the big brands here in the US). 

The biggest problem second to propane availability is pre-heating it. The mixers generally require a heat source to properly atomize the propane. Conventional cars use the coolant but that option doesn't exist in an air-cooled car. Some say one could use the oil in an air-cooled car to preheat the system but that's beyond my knowledge. I'm confident one could use exhaust heat to the same effect.

Incidentally turbocharging lends itself beautifully to LPG conversions. The engine's efficiency can be increased by increasing the boost pressure. Simply reduce the boost pressure/efficiency to run pump gasoline.

I admit that my LPG experience is limited to V8 applications in friends' and colleagues' cars. But from their reports there is incredible power potential with LPG. And fuel economy doesn't necessarily have to suffer. You just have to modify the engine for the application.