increasing model E output/hp?

[TTF100]

webbew's question: i sorry mate i have no experiance with technocarb however 400hpongas did some testing with one, and his results seem to show an improvement with two converters here's his post

400hpongas wrote this:

After many years of testing all the different "Fumigation" systems Ive learnt a thing or two
When it comes to "Flow" rate you would be surprised
On the same 355 holden stroker ,(pulled 435hp on the engine Dyno on ULP98 with 800cfm DP)) with the same inlet manifold (Torquepower Hi-rise single plain air gap)
A single Impco 425 single E convertor 215 RWHP
A single OHG 450A single E convertor 230 RWHP
A so called Big Block TechnoCarb with one Airod convetor 210 RWHP
A so called Big Block Technosarb with Twin convertors 225 RWHP
Twin GRA mixers a 400 and 440 twin B2's fully tuned 235RWHP
A PG806 quad throttle body ,shared barrels 1 vialle F and 1 ohg X1 convertor 287RWHP
A PG806 quad throttle body , Seperated barrels , twin OMVL90 324RWHP
So on the same engine you can go from 210 to 324 RWHP by having the right setup !!!!
So for a almost std 304/308 the Impco 425 is plenty good enough
For a bit more then go the OHG450a (if you can get one
For Looks , go the Technocarb , it wont do much more than the OHG450a
Dont use GRA's unless your going to Blow it , there hopeless !! (Properly tuned they are quite smooth and tractable , but they just loose it over 5000RPM

[MLGPropane2]

TTF100

The Impco model E is fuel flow limited by the I.D. of the fuel inlet tube. 0.197" diameter

This is the small tube that is just below the ist stage "seat" a flat metal strip with a thin piece

of "rubber" bonded on one side.

Roger

[Steptoe]

Have u actually tried reeming it out a little, see what happens?

[MLGPropane2]

Steptoe

It is a very thinwall steel tube..pressed into the Aluminum casting.

No changes allowed here in the Unuted States...Safety Approvals

Regards

Roger

[Johnmaster]

Looks good, surprised you were able to fit everything in there! You should have bought stock in goodyear rubber hose:)

Naturally aspirated my 323 should flow 436 cfm (assuming 85% efficiency which is a guesstimate)
rate= (displacement ci x rpm x .5 x Ev)/1728 if my formula is correct.

To estimate forced induction airflow I multiply the rate times the pressure ratio and come up with 793 cfm at 12 lbs boost (1.82 pressure ratio).

The math makes it seem like I am way undersized for using this as a turbo mixer. What changes under boost make this still a good mixer for the job?

[TTF100]

that 793 cfm your talking about is mass flow [cfm of air going into the turbo inlet], as long as you place the mixer in blow-though configuration [between the turbo and the engine] it will still only have to flow the 436 cfm that it flowed in NA form, it's just it will be 436cfm of 12psi air.

however if you put it in draw-through configuration [before the turbo inlet] it would have to flow the 793cfm of atmospheric pressure air [not gonna happen].


so in short put it in the blow-through configuration and it will have to do no more than its doing now.

also one thing to note: it is a good idea to beef up the bolt that holds the hat on top of the mixer [if your going to go blow-through], i have drilled out and tapped mine to 3/8 UNC.

[TTF100]

MLGPropane2 wrote:

TTF100

The Impco model E is fuel flow limited by the I.D. of the fuel inlet tube. 0.197" diameter

This is the small tube that is just below the ist stage "seat" a flat metal strip with a thin piece

of "rubber" bonded on one side.

Roger

thanks for reply Roger your point interests me greatly, as it is a possible explanation for what was happening to me, i definitely sound's more likely than it running out of vaporization as the air/fuel ratio got leaner not richer. is there a ruff estimate of horsepower rating where this becomes a restriction?
also i was thinking maybe the australian auto-mix i use [butane/propane mix] with its lower tank/line pressure [compared with pure propane] could be exaggerating the problem further?
pure propane is available here but only at certain filling stations, could this perhaps explain why the guy with the turbo 265ci made as much power as me with only 1 model E?
i had previously disregarded that tube as a restriction because of the difference ratio between the volume of the vaporized gas compared to that of liquefied gas, however you have run into it being a restriction so now it's got me intrigued
what was the setup or setups that you found this to be a restriction?

[MLGPropane2]

TTF100

In another life..in the 70"s I built LPG engines for offroaders. Using a Taylor 1000 HP

dyno...stedy state step testing (200 RPM increase per step) Engine: 427 Ford sideoiler

with 428 crank 460 CI. Impco 425 piggybacked above a gutted Holly 850. started seriously

leaning out 325 HP with one Model "E". With 2 "E's" T'd to the single 425 600 lbft

and 600 HP at 5300 RPM Started to lean out again at 6000 RPM

HD-5 LPG lab tested 97% Propane 1.5% propene 1.5% butane

Oh..Medium riser heads 13.5 compression ratio

Regards

Roger

[franz]

Hey Roger, I think I remember that engine. Wasnt that the same Don Bass played with too? I remember being in the Impco lab with him way back. He had a Dodge 440 and I think a Hemi too, and some big block Fords.

Franz

[MLGPropane2]

Hi Franz,

Similar engines (Don Bass) The Impco engine was for Vessels Farms (Los Alimitos Race Track) Baja 1000

truck. The Dodge Charger (Propane X) evolved from a 426 Hemi with two 425 @ two Model E

to a 440 with Three of each on a Don Bass constructed tunnel ram intake manifold.

4400 lb car Ran 145 MPH 10 sec qtr mile.

My shop was in La Habra Calif

Best Regards

Roger

[Johnmaster]

that 793 cfm your talking about is mass flow [cfm of air going into the turbo inlet], as long as you place the mixer in blow-though configuration [between the turbo and the engine] it will still only have to flow the 436 cfm that it flowed in NA form, it's just it will be 436cfm of 12psi air.

however if you put it in draw-through configuration [before the turbo inlet] it would have to flow the 793cfm of atmospheric pressure air [not gonna happen].


so in short put it in the blow-through configuration and it will have to do no more than its doing now.

also one thing to note: it is a good idea to beef up the bolt that holds the hat on top of the mixer [if your going to go blow-through], i have drilled out and tapped mine to 3/8 UNC.

I see, so provided the mixer can flow enough fuel to match the mass of the air flow it sounds like it should be sufficient. Is there any conclusion on roughly how much power a model E can really support? I have mine mounted right to the mixer now but there is not room for 2 so I hope I don't have to search for places to put them. I like having the E directly mounted but short hoses would suffice if I cant squeeze them in where I want them.

That 1/4" thread does not seem strong at all. The hat I am using has (4) 1/4" bolts around the perimeter to clamp it to the base flange and an o-ring for sealing the boost in, I borrowed it off my sled for the time being but I will have to flip big coin for one when I want to use my sled or sell it.

[TTF100]

MLGPropane2: thank you that is excellent info, when you were testing did you test the primary and secondary pressures? just to be shore it was the liquid passage in, that was the flow restriction and not the passage between the primary and secondary chambers?

[TTF100]

Johnmaster: as for the power limit of the model E, MLGPropane2 has showed in real world testing that the power limit is 325hp for one model E.
what i am now trying to determine is what the restriction is, it must be a flow restriction because it goes lean when they run out not rich [if it were reaching its vaporization limit it would start producing ever more dense vapor until it started spitting actual liquid resulting in a ever richening fuel curve].
so that seems to conclude its a flow restriction, what i want to determine is, weather its the passage for the liquid in, or the passage between the primary and secondary chambers that is the restriction.
i am keenly awaiting MLGPropane2's answer to my above question as im hoping he will have the answer

as far as the turbo thing goes if its the liquid in line that is the restriction then it will produce no more hp under boost than it did in NA form, but if its the passage between the chambers that's the restriction then the density of the vapor will come into play and it will be able to produce more power under boost than it can NA.

[Johnmaster]

Thank you, I am curious to hear the findings as well! I am at the point now where adding another mixer, while inconvenient, would be easier as I haven't designed some of the other obstacles that will be in my way yet. I am hoping the liquid port is not the restriction:)

[J. W.]

I wanted to pass this info on and see if the experts can help some more with it. I have know Idea about how this works and had mine installed.

I have a prins system on a 03 ford ranger 3l. flex. I was advised to tighten the spark plug gap and put in a cold plug because propane burns hotter. My gap calls for 44 and I was told to tighten it to 35. I did both and my horsepower and km/l. improved by about 1.5 km/l highway I was happy with that. The funny thing, it also improved on gasoline. I hope this helps somebody and if it does can you let us know?

I find propane does not like e85. Could this be the reason? I would love to be gasoline free.

Thanks John