BIG power from only 2 convertors

Propane, Butane, LPG, GPL, C3H8, C4H10
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BIG power from only 2 convertors

Post by mattwray » Sun May 11, 2014 12:40 am

I have a link to a guys propane big block car that looks make 1500hp on just 2 impco L convertors (maybe x-1's) How is this even possibe?

I ask this because i have a 468 bbc with a 80mm turbo and it is not supplying enough at the moment with 2 b2 convertors at less than 10psi.
I have also seen the valiant 6 cylinder with a single model E make 280rwkw, should i just get two model e's as my setup is roughly 2x bigger?
Not keen on fitting 3 or 4 convertors, will 2 convertors feed 800-1000 engine hp?

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Re: BIG power from only 2 convertors

Post by mattwray » Sun May 18, 2014 3:52 am

upon reading the thread about getting more power from an impco model E convertor, maybe my issue is tank pressure/flow. Has anyone heard of heating a lpg tank to keep the pressure up? You can buy small 12v stick on pad heaters but i dont think they will make alot of difference due to their size.

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Re: BIG power from only 2 convertors

Post by C3H8 » Sun May 18, 2014 5:06 am

Your not getting many replies. I suspect this is because most of us in the industry can't really answer your question. Theoretically it is not possible to get 1500 HP from only 2 regs and 2 425 mixers. The regs on this unit appear to be OHG regulators. I suspect there have been some serious mods done to both. The main mod in the regulator might include enlarging the primary inlet and enlarging the secondary outlet. On top of this the flow through the heat exchanger would have to be increased. I can't think of any mods to the mixer that would allow you to get 750 HP per mixer.

As for heating the tanks. Quite possible, but only required in very cold temperatures. Tank pressures are normally in the 100 PSI area and greater at temps over 70F. More then enough to supply any engine, even high HP applications. Companies in Northern Canada used to heat their tanks in the winter by wrapping copper tubing around the tanks and sending engine coolant through the tubing. This was in areas where the temperatures reached 40 to 50 below zero though. In these areas the engines were seldom shut off until the temperatures warmed up. The coolant flow was shut off with a manual valve as soon as milder temperatures were reached as the heat could cause the tank to reach a pressure that would activate the PRV.

Even though propane has a theoretical value of zero PSI at around 40 below I used to drive my 1980 Dodge 318 at those temps without a heater. One morning I got up and the temp was 42 below F. After some fussing with getting it started and it did start where many of the gasoline vehicles would not, I took off down the highway. After driving about an hour I pulled into one of our dealers where the engine stalled. Opened the hood to find oil all over the place. Figured I had blown a timing chain cover. After getting it inside we found the PCV system had froze and pressurized the crankcase causing oil to blow out the dipstick. The reason I mention this is to show you don't need a lot of pressure to push enough liquid to the regulator to supply an engine.

The one factor that would vary is that you guys with turbos would need a tank pressure that would be at least a few PSI higher then your maximum turbo pressure.

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Re: BIG power from only 2 convertors

Post by BigBlockMopar » Thu May 22, 2014 8:08 am

I've seen the truck before a few times but when I tried to find some more info just now there wasn't much that came up, other then a few pics on the HAMB-forum and some info it did 161mph on ElMirage. ... 403/page-2

Maybe just contact the owner/builder and ask for more info?
'73 Dodge Dart - 360ci - 11.3:1cr
MegaSquirt + HEI 7-pin timing control - Edelbrock AirGap - Cold Air Intake
IMPCO E / 425 mixer - A518 OD-trans - 3.55 gears - 225/50/17" tires.

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Re: BIG power from only 2 convertors

Post by GriffsGarage » Thu Nov 16, 2017 5:36 pm

If you look at the photos from behind the engine looking at the back of the intake manifold, I see what looks to be a nitrous type fuel rail/fuel nozzle. These look to be attached to a pair of nitrous or LPG solenoids. At a guess I believe the owner may be running a pair of Hobbs pressure switches to control the aux solenoids fitted with jets, which on boost will spray liquid LPG into the intake once it reaches a predetermined intake boost level, with a second solenoid activated at a higher boost level to increase the fuel supply to prevent the engine from bogging down which may occur if it were 1 big hit of liquid propane.

All this is purely guesswork of course....

Ideas anyone? Has anyone on here tried spraying liquid Propane into the intake like this?
It's a bit like the old Turbo cars we used to get around running extra boost with standard ECU's fitted with extra injectors running off a Hobbs pressure switch.

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