71 Chevrolet Camaro RS

Let's hear all the gory details about your car and how it became alternative fuelled.
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Posts: 4
Joined: Sat Jan 13, 2007 2:21 pm

71 Chevrolet Camaro RS

Post by Martin71RS »

Hi all....I'll start by introducing myself.

My name is Martin, I live in The Netherlands and have driven my Camaro on LPG daily for over a year.

It is a dual fuel system consisting of a Holley 600 vac sec for running on gasoline and an OMVL vaporizer/mixer for LPG. Ignition is a HEI with high voltage coil. Engine is a 350cui sbc, Weiand manifold and headers followed by a Flowmaster dual 2.5" system.

I copied a part of my webpage www.pro-touring.nl to show what my conversion looked like.

Since fuel is very expensive in The Netherlands I changed to LPG (or Propane) because I wanted to use the Camaro as a daily driver.
The price of LPG is about 1/3rd of normal fuel.
On normal fuel consumption was 1 liter every 4,5km or 10.6mpg.
Normally fuel consumption on LPG would be more, but in my case it is actually less!
I think the carb was running a bit rich.
Now it does 1 liter LPG on every 5km or 11.8mpg.
I must say I like driving/accelerating fast, so maybe these numbers may seem high to some people.....
Probably with "normal" (slow) driving and a very well set carb you could get 1 liter to 6.5km or 15mpg.
This is the filler cap which is located behind the license plate so it is not visible normally.
The LPG tank in the trunk is a 60 liter one and can be filled to a maximum of 80%.
This is the fuel solenoid which shuts off the supply when running on LPG.
The vaporizer is mounted on the passenger side inner fender.
The engine coolant is used to heat the liquid LPG and transform it to gas.
Two feed lines bring gas to the mixer.
The mixer is mounted on top of the carb inside the air filter.
When running on LPG the carb only functions as a throttle body.

this is a full pic of the Camaro (actually running on LPG here)
and I even have a movie that shows it's fast enough:
disclaimer: closed track, professional stunt driver blablablabla 8)

By now I have a new motor, a 400cui small block Chevy (10.5cr) which I will run on LPG only.

I have been thinking about it a long time and now decided to go 100% LPG. To get the most out of my engine I ordered a Technocarb mixer. The previous owner of this engine ran it with a OHG450 system and dyno'd it at 340HP at the wheels. (we made a testdrive before I bought it...WOW!!)

So I can't wait to finish my car and get it on the road again. I will make an update when I get the set up and running.

Posts: 303
Joined: Sat Jun 03, 2006 3:59 pm
Location: Netherlands

Post by Imperial73 »

Hi Martin, so you found your way to this forum! Welcome!

Posts: 72
Joined: Sun Jan 14, 2007 11:25 am
Location: Holland, Europe

Post by Helmet »

Nice too see two Monkeys/AAPen! :lol:

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Joined: Sun Feb 18, 2007 11:55 am


Post by stroker »

Hi, saw your ride on a propane forum and had to talk with someone that might have gone though the same type of high performance teething pains that I am now going through. First I built a 4x4 1 ton campervan and then converted to propane, this was 5 years ago. The motor was a 350 30 over 250 cam 1.5 rockers 9.5 compression heads mildly ported and of course balanced. I was running the largest Vaille vaporizer made, along with a 650 cfm Tecnocarb mixer. This system gave me 50,000 miles of trouble free service and I do mean trouble free, -20 +35 C easy to start, plugs were changed at 35.000 miles and was not necessary, went through air care without ever having any problems, however being a bit of a gear head wanted more. So I did my research and designed what I think is the correct motor for my application. 383 Stroker with 11.2 compression X4254H cam with 1.6 roller rockers, lift corrected to .477 / .492 / RHS Vortec heads ported to flow 260 in 184 ex at .500 lift, Along with the this I went to 0 dec height, used Beehive springs, total seal gapless rings. Now you have an idea I might have a bit of knowledge, I will tell you about the dyno and road test.

The builders suggested that I break the engine in on the dyno on gas, this produced 416 HP at 4900 RPM & 494.9 TQ at 3800 RPM however 477 TQ AT 3000 RPM. Now we hooked up the aforementioned propane system and were building good power until 3600 RPM and then just like too small a fuel pump the engine leaned out and lost power. I had a very good idea this was going to happen, so contacted Tecnocarb, drove out and picked up a new Vaporizer and Mixer. Once installed and back on the dyno the engine produced 386 HP and 452 TQ, I was happy with the results and installed in my van. Another thing I should mention is this engine developed 19.5 inches manifold vacuum at 900 RPM. The van was already running headers and mandrel bent 2.5 stainless exhausts, so just a straight forward install. I have since drove this vehicle 2000 miles and it is hard to start, vaporizer freezes at plus three C, will not idle, as in you can set idle at 900 RPM and turn engine off restart and now the rpm is 1600. I realize this sounds like a vacuum leak but I disconnected trans and brake vacuum hoses and but a plug in manifold, removed mixer installed new gasket and there was no change in the results The only thing this system does well is go fast, under full throttle pulls strong, no hesitation from stop, however if I accelerate hard and slow down to 10 miles an hour engine tries to die and I have to feather gas peddle so engine does not die. I talk with another propane guy that told me to run my old vaporizer on the front of my mixer and run the new tecnocarb vaporizer on the rear and turn the idle screw all the way in. This is not what I want to do; I will go back to my old motor and use the new motor with an injection system on a vintage ride before I do this. I am beginning to wonder whether I have a faulty vaporizer or if it needs to be electronically controlled. Okay, do you have any ideas to help steer another propane guy in a new direction to sort out this problem.

Thank You in advance for any and all thoughts
Sincerely Gerry Vass

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Joined: Sat Jan 13, 2007 2:21 pm

Post by Martin71RS »

well, it's time for an update....car still isn't running but most of the installation is in. I have some wiring left to do and hope to start it soon.

For now I will run 1 vaporizer but I have a second one if 1 proves to be insufficient.



Posts: 4
Joined: Sat Jan 13, 2007 2:21 pm

Post by Martin71RS »

well, my car is almost finished and I am driving it now.
I am very pleased with my setup, idles smooth and revs quick.
easy to spin the tires too :D

on a recent trip I measured the consumption
at around 65~70mph for 80miles it ran 12.95mpg
When I go faster or play a bit more it quickly goes up to 7mpg.

I topped out at 130mph, this is when my converter/vaporizer could not give enough anymore....I should put in a second one to get max power but I think it is fine for now.


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Joined: Fri Feb 02, 2007 8:32 pm
Location: JAFA , New Zealand

Post by Steptoe »

If u go back over older posts , u will see i have a matching numbers 69 camaro...been on Dedicated LPG since '86, around 200,000 miles on LPG
Impco E running the old obsolete EC1 front plate
Impco 425
Performer dual plane
Cast small chamber 202 fuelies
ACL flat tops giving just under 11:1
I have experimented with several custom designed cam profiles over the yrs...now is basically a low duration, high lift blower cam, with slow ramps, advanced 2 degs for bottom end
Basically all internals are stock.
Custom Modified GM HEI (springs, total cent, and vac advance)
Cast iron Rams horns
Dual 2 1/2" exhaust with crossover pipes

Cant rem if a 60 or 80L tank..(so long since put it in) but from near MT, takes about 45L

On a trip, pass a couple trucks, hit 110/120 mph, cruise a couple staights around the 90 mph....75 miles 27 to 29 L
Converting cost per mile to petrol equivilent running about 33 mpg
Around town, 3 to 5 mile stop start, a hill and 5 interesections drops to about 22 to 25 mph equivilent.

Will pull a high 13 sec 1/4 mile

On the dyno, starts to lean out mid 4000 rpms, gets a little serious around the 5200...but not worried about that cause we dont have the roads to cruise at 130 /140 mph for any length of time.

Trans is 350 turbo low stall converter (1200/1400) and 308 posi diff
Going to a low stall recently, has made a substantual diff to economy arud town, and slightly on the open road....I do not beoieve with this stall I could do a high 13 sec 1/4 mile, more like a mid 14.
The old stall converter was a 2500.
With the 2500, bliping the rear wheels on normal take off, or a damp road pulling into traffic without the rear breaking loose was a pain in the butt.
Its only about a 30/45 job to swap converters if need be.

For the future, Im considering going to a 700R or similar trans....lower 1st gear and open road would cruise under 2000 rpm..which would go well with the bottom end cam thats in the car.
My Spelling is Not Incorrect...It's 'Creative'

Posts: 4
Joined: Sat Jan 13, 2007 2:21 pm

Re: 71 Chevrolet Camaro RS

Post by Martin71RS »

I have not been active on this forum for a long time, but I think I should let you guys know I've updated my page again recently.

I've now run a 14.4 @ 100mph in the 1/4 on LPG so I am pleased with that.
(even have some movies of me racing on pages 46 and 47)
for races I intend to do a carb swap (gasoline) but for normal driving the LPG set-up gives enough power and keeps the fuel costs down.

see www.pro-touring.nl for more


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