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i have a XC 302 and i was recommended not to gas research it as it was not good for older engine's such as the 76 cleveland.

is this correct?
 

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Whats traction?
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Re: Re: LPG systems for Clevo's

SXC_302 said:
i have a XC 302 and i was recommended not to gas research it as it was not good for older engine's such as the 76 cleveland.

is this correct?
Gas research is just a different way to get the gas into the engine. No two companies share the same design, gas research uses a throttle body(s) to allow gas into the engine.

It is the only system I have seen that can flow 800+ cfms and still be somewhat drivable. The other options tend to overfuel too much at low-mid rpms.

LPG in general is not good for stock leaded engines. It needs to have hardened seats or a valve lube to stop the valves from wearing into the head and LPG likes more compression too. Dual fuel systems are crap and never allow either fuel to perform at their best.

I love gas and it will run in just about any engine on the planet, it just has to built and setup to run properly. If I was to put a petrol carby on my engine as is, i would lose 10-15% power, just because the engine was built and tuned for straight LPG. Too many people do the reverse and whack straight gas on a petrol engine then complain it runs worse, of course it does.
 

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we had that sprintgas setup on a 351, worked well, and pushed the car into 12.7 passes.... the motor was built for gas performance, as we got rid of hte fuel tank to run twin exhausts.. was an xd ghia
 

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Discussion Starter #24
What did you use as a throttle body under the Vortex mixer? What kind of inlet manifold were you running?

Thanks,

Chris.
 

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not identical, but somethign like that, like the one on the site, didnt know how it went on petrol, only time it saw petrol was when it ran outof gas, but thast a different stroy
 

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V8 GT pilot
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Hi Guys,

Interesting chat about LPG.
I own a 1982 ESP V8 that has been running on straight LPG for 9 years.
It runs a crane 272 cam , 302 heads with 351 crank ( comp has been lowered to run approx 9.5 : 1 )

Impco 425 carby on Holley plate 1/2 inch phenolic spacer, a single B2 converter , Shaker scoop
LSD 3.23 gears in the rear
Tri Y Genies into twin 2 1/4 ( No petrol Tank )
C10 Auto 2300 stall
Crane Hi 6 Ignition and Coil Bosch Electronic Dizzy
YT Rollers

This combo has given me 170 Rear wheel Kw and a quarter time of 14.3
at Calder.

I have also tried a brand new OHG 450 Gas carb but found it to be very difficult to tune and tailor. It ended up being quite boggy so I went back to the 425.

I also run a K & N Hi Flo filter inside the Shaker and have found it to work extremely well. I will also try the paper element to see if that makes a difference. Another post suggested that the paper filter was better suited to the 425.

I have found that most important feature of a good LPG motor is its vaccuum. You need to run a good vaccuum cam otherwise the car will run extremely rich at low throttle and will lean out dramatically at High revs. This is because the motor is the actual " sucker " of the fuel unlike Petrol engines where the fuel is forced in by the petrol pump.

I would be interested to hear from you guys about compression ratios for your LPG engines and the type of Head / Piston combos you are using. I have been recently told to keep the compression ratio to a max of about 9.5 : 1.

I was thinking of upping this to 10 : 1 but have been warned against it.
Apparently our current 50 : 50 LPG mix is not what it used to be.

Great talking with ya
 

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Discussion Starter #29
It's good to know that the Impco rig can get good usable street power. That's what I've booked the thing in to have installed. Will let you know how I go after the works done.

I just figured that it's a common beast and there's a lot of them around. That way I know it's going to be supported in a few years and not dropped like a hot spud because some company in Italy goes under or something like that.

Thanks to all for the info on this thread.

Chris.
 

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Whats traction?
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ESP said:
Hi Guys,

Interesting chat about LPG.
I own a 1982 ESP V8 that has been running on straight LPG for 9 years.
It runs a crane 272 cam , 302 heads with 351 crank ( comp has been lowered to run approx 9.5 : 1 )

Impco 425 carby on Holley plate 1/2 inch phenolic spacer, a single B2 converter , Shaker scoop
LSD 3.23 gears in the rear
Tri Y Genies into twin 2 1/4 ( No petrol Tank )
C10 Auto 2300 stall
Crane Hi 6 Ignition and Coil Bosch Electronic Dizzy
YT Rollers

This combo has given me 170 Rear wheel Kw and a quarter time of 14.3
at Calder.

I have also tried a brand new OHG 450 Gas carb but found it to be very difficult to tune and tailor. It ended up being quite boggy so I went back to the 425.

I also run a K & N Hi Flo filter inside the Shaker and have found it to work extremely well. I will also try the paper element to see if that makes a difference. Another post suggested that the paper filter was better suited to the 425.

I have found that most important feature of a good LPG motor is its vaccuum. You need to run a good vaccuum cam otherwise the car will run extremely rich at low throttle and will lean out dramatically at High revs. This is because the motor is the actual " sucker " of the fuel unlike Petrol engines where the fuel is forced in by the petrol pump.

I would be interested to hear from you guys about compression ratios for your LPG engines and the type of Head / Piston combos you are using. I have been recently told to keep the compression ratio to a max of about 9.5 : 1.

I was thinking of upping this to 10 : 1 but have been warned against it.
Apparently our current 50 : 50 LPG mix is not what it used to be.

Great talking with ya
10.5:1 comp is a walk in the park for LPG engines. Many years ago 13:1 was possible but now there is too much butane mixed into LPG for that.

Would agree 100% that good suction is critical for LPG and the impcos with spacers are a very good choice, a 700 series holley base is good too as the 600 series (which are more popular because they are easier to find) tended to strangle my engine. I have dyno sheets that show the K&N to be fine with the 425's, i think the engine in the other post may have had a knackered filter or suction problems as mine doesn't loose any power at all with the K&N filter setup on there.

There is also a lot of work that can be done to the impco's to get more flow too.

Also, as a bonus, i've found the impcos to be extremely reliable which is a major bonus.

Good luck.
 

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Discussion Starter #31 (Edited)
They are using my thermoquadbase for this conversion. The thermoquad's flowed about 800cfm so the problem you mentioned about poor flow with 600 Holley's shouldn't be any problem for me.

One thing about compression is that the cam choice affects how much compression you can run be it on gas or petrol. 10:1 shouldn't be a major issue on just about any gas engine although mine will be on the edge as it's only got a Heatseeker stage 1 gas cam in it which is smaller than the stock clevo cam although it's a dual pattern cam. 258 degree intake and 264 degree exhaust seat to seat with only 0.440 thou lift.

Even at stock timing on a hot day it get's a bit pingy on optimax which is only 1 point lower octane than most gas is now. I don't know if my dizzy is graphed perfect but it will be once the LPG goes in so I'll find out soon enough.

If I put a bigger cam in it it would be perfectly happy at 10:1 or even a tad higher.

But even with the stage one cam in it Desktop Dyno predicts 302HP at 5000RPM and 372 ft/lbs at 3500RPM on gas.

It's no monster but it's better than driving a datto!! :s6:

Thanks again,

Chris.
 

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Chris Brooks said:
They are using my thermoquadbase for this conversion. The thermoquad's flowed about 800cfm so the problem you mentioned about poor flow with 600 Holley's shouldn't be any problem for me.

One thing about compression is that the cam choice affects how much compression you can run be it on gas or petrol. 10:1 shouldn't be a major issue on just about any gas engine although mine will be on the edge as it's only got a Heatseeker stage 1 gas cam in it which is smaller than the stock clevo cam although it's a dual pattern cam. 258 degree intake and 264 degree exhaust seat to seat with only 0.440 thou lift.

It's no monster but it's better than driving a datto!! :s6:

Thanks again,

Chris.
You may find with LPG the pinging will improve, just make sure the dizzy is recurved and the whole setup is tuned by a good dyno tuner. Even with the small cam i'd say 10:1 should be OK.

The base is all about the size of the butterflies, if i remember correctly the thermoquad has similar size butterflies to the 600 base (40mm) while the 700 holley base has 45mm butterflies. Again, the thermoquad or 600 should be fine for your engine is not as cammed up as mine.

A set of extractors and a free flowing exhaust might help if you have not done so already.

PS. Anything is better than driving a datto ;)
 

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I have a Impco 425 on a thermo base on a 351 XC witha C.O.M.E CBSH300 cam. The engine is a otherwise stock open chamber 2v with re-curved dizzy, it runs 16.0 @146kph with 2.75 diff, weighs 1780kg but only gets about 22l/100k's. What sort of consumption are you getting?
 

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V8 GT pilot
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xdc 351


Are you able to elaborate on these " tricks " for the Impco 425.
Who is your contact in Melbourne that knows how to tickle them.

Cheers Mate

XXESP
 

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V8 GT pilot
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Full tank = approx 70 litres usable
I get around 280 - 300 k,s cruising nicely
If I get heavy footed , i need to visit Shell at around the 180 - 200 Klm mark

Normal around town driving = around 220 - 240 klms

I have found that the type of oil has a lot to do with the consumption.
I currently use the Castrol Formula R full synthetic 10W - 60 oil.
I will cahange to the new mobil 1 soon which is 5W - 50.

My friends have used this Mobil oil before and have noticed a difference in HP and fuel consumption.
Remember that the new FPV vehicles use the 0 - 40 oil.
This is how they get such good HP and economy figures.

The clearances are set up for this so I wouldn't go to anything less than a 50 oil for a Clevo. But then again , depends on how your engine builder has set up all the clearances.


XXESP
 
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Here's a pic of my mixer being inspected by a top engineer.
It is minus feed pipes in this shot.

Pete.
 
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Sorry, it seems the jpeg is still too big.
Email me for a full size picture.

Pete.
 
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