Cam comparison: hydr. FT vs hydr. Roller

[77cruiser]

With LPG vs. gasoline isn't the mileage about 25% less? And around 100 octane?

[Promodwrench]

Talk to Mike Jones he can tell you what you need
to get the extra power you're looking for and keep it
Mild mannered enough for daily driving.

[PRH]

With LPG vs. gasoline isn't the mileage about 25% less?

And then there’s that.

[BigBlockMopar]

I realize parts availability for this stuff must be crap over there compared to here........ but I would think a pretty basic low cr 360 with bowl blended 1.88/1.60 heads, small-ish solid cam, headers, something like a sniper EFI along with a factory high stall converter with a 904 and 2.76’s........ would be a pretty decent daily driver type combo that would still pull down better than 13mpg on regular unleaded.

Anyplace near you with a dynojet dyno?

I've had the car on a Land&Sea hub-dyno for 4 times.
Last time out the car put out 234 rwhp @ 4700rpm. Given the 'heavy' truck-transmission, that would net something like 260hp on the engine I guess. (I would love to be able to add 100hp to that, or at least 100 engine-hp, but that would be a stretch with just a cam and unported heads.
The current LPG-fuel system was starting to lean out the mixture from 3800rpm up. That will be fixed too in time.

It's known that Propane makes less power than gasoline on the same engine and setup, but some of that power can be found back by optimizing ignition timing.
I still like to do a back-to-back comparison on the dyno between to gasoline and propane. Just to get an idea how much difference there really is.
Mike has been in contact and also opted for a 268HR.

[Roundybout]

Propane has about 27% less energy per gallon compared to gasoline. Higher octane though as we know, so if compression and timing were optimized for each they're pretty close on power output.

Stoichiometric ratio for gas is 14.7 and 15.5 for propane so they're not that much off from each other compared to say methanol and gasoline. Propane is a much cleaner fuel also.

[PRH]

234rwhp seems like a pretty small number to me for the amount of time and effort you’ve put into it, but the overall combo doesn’t scream “high hp” either.

I guess if you’re intent on sticking with the LPG, to some degree you’re going to be finding your own path.

On the other had......... 1hp/ci on pump gas(at the crank) out of a pretty mild 360 is pretty much a slam dunk.

Here’s a 340....... cast piston bottom end, very mild bowl blended 587’s, 2.02/1.60, 268H,
650dp, std performer, 1-5/8” headers.
Went in a lil red truck...... and was pretty peppy to drive.

EF833D7F-7D58-471E-A90D-74AEBF3608FE.jpeg

With a RPM intake and a XE268 type cam....... it would have probably picked up 25-40hp

[PRH]

Is there any kind of drag strip, or a timing system at an old air strip, etc, near you.......where you could run the car and get an ET/speed on the current combo?

You’re using 302’s on the 360 now?
Stock valve sizes and no porting?

[paulzig]

Half the price but you use about 20-30% more of it...

I screwed around with the stuff ages ago, and no matter what was done it would not beat an out of the box untuned Holley carb.

The fact that the propane goes in hot and has no cooling effect, less BTU, less charge density makes it only worthwile as an alternative fuel for around a 25% savings on running cost.

IF you are using it for power, forget it... before you do anything, is there a Holley or something you could borrow to try and see for yourself?

[BigBlockMopar]

I've had a look at the current gasoline-price, as I hardly fuel up with it.
Our current local prices are:
€1.78 for 1 Liter of premium Gasoline.
€0.59 for 1 Liter of LPG
Turned out I was wrong about 'about half' the costs. LPG is actually 1/3rd the price of gasoline.

Dwayne,
Yes I 'm using the small 318ci "302"-heads on the 360ci.
My reasoning was they add CR and since this is daily driver, RPMs hardly ever go above 3000.
Stock valves indeed. I just polished the chambers and removed the casting roughness in the small ports.

No local or any 'real' dragstrip here in the country.
Just an airstrip about 2.5 hrs away where some dragraces are being held a couple of times a year.

[PRH]

When you had it on the hub dyno, have you ever try it with a carb and gasoline?

Even if it required premium fuel and octane boost for the test....... it would be interesting to see just how much power you’re currently leaving on the table.

I’d just rig up an outboard remote fuel system to use for the test, if that stuff is no longer in working order in the car.

At those fuel prices........ something like a turbo WRX starts to look attractive for a peppy DD(turbo GTI, civic with a turbo, etc).
26mpg on gas would get the fuel cost per mile a lot closer to 13mpg on LPG.

What kind of LPG fuel delivery system is required to provide adequate flow and pressure to support something that would make about 400hp(crank) on LPG?
Sounds like whatever you’re using now isn’t quite keeping up with what you’re currently making for power.

[BigBlockMopar]

At the dyno, time is always limited, eventhough the operator has been very lenient with time and help every time I was there.
The most recent dyno run was with the 360ci engine in place (other 3 with 318ci engine), and I was mainly looking for a torque and power-number it delivered and if my timing was what the engine wanted.
https://www.bigblockmopar.nl/2018/09/do ... dynoday-4/

The gasoline parts are all gone in the car but a simple fuel-supply from a fuel-canister would be easy enough the set up, if the Dyno-operator is up for that.

The LPG carb is an IMPCO 425. The 425 somewhat depicts the airflow (max 450), and this carb (and LPG vaporizer) are usually rated for about 300hp.
My LPG system has some older fuel lock-off/safety valves, which have a limited internal diameter, further restricting the system at higher rpm and powerlevels.
Seeing the AFR's lean out during the dynoruns, tells me the IMPCO-carb isn't the issue (yet).
My first 'change' will be installing a large filter/canister right before the vaporizer, which also doubles as an extra liquid supply nearby.
If one wants to make more power on LPG, you'll usually need to double-up on all the fuel supply parts.

I really would like to try out gasoline as the fuel on a next round on the dyno.

[PRH]

As I’m sure you’re well aware, the small heads small cam combo aren’t remotely adequate if the goal is truly 100hp more at the crank than you’re currently making.

I guess what I’m saying is......perhaps the LPG isn’t holding it back all that much in its current configuration......... but my instinct is..... it’ll be more of a handicap on something that’s making a legit 350-400fwhp.

On the engine dyno here, I’d be pretty(very?) surprised if that motor, as it sits now(except on gas) made 300hp.

[BigBlockMopar]

I have good hopes for the SpeedMaster heads I will install right along with a cam 'update'.
The current engine was built purely with focus on low-rpm use (torque) and economy. I failed the economy-class obviously, but this engine was a very nice upgrade to the previous 8.6:1cr 318ci, with which I managed pretty much the same mileage...

I will see if I can find a one-lane patch of road here to do some testing.
Long straight roads are scarce overhere and I also live in the busyiest part of the country.

[cjperformance]

Forget the cam . You need a second mixer on there. You're at the limit of the single 425 in n/a form. Yes ,if yoy are leaning out up top then you have a feed problem. If you have enough fuel available to the 425 they go rich up top as the engine pulls more vac under them. But still you are at the point where it is holding you back.
Get a dual 4 barrel intake if they are easily available for your engine. Use 2 x 425 mixers and converters to suit. With nothing else touched you will make more tq/hp everywhere on that combo.

[PRH]

something like this for a SBM

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