Who's run a tunnel ram and propane?

Propane, Butane, LPG, GPL, C3H8, C4H10
dent
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Who's run a tunnel ram and propane?

Post by dent » Thu Feb 28, 2013 8:51 pm

After dismantling and selling off most my turbo small block truck in order to buy a house, I'm once again trying to get my truck back on the road. This time I'm planning on running a mark 5 454 i had sitting in the shop. Still collecting parts but I have both a dual plane and a tunnel ram sitting here and was wondering if anyone has had any experience running one on the street with propane? Engine will be about 10:1, haven't pick out a cam yet but it will be a hydraulic roll with about 230 duration And somewhere over .500 lift, I have both rectangle port and oval port close chamber heads but haven't decide which one to run yet. Truck will have 3.54 a turbo 400 and 33" tires. I'm wondering if I'm better of leaving the tunnel ram on the shelf and running the dual plane with a 2 to 1 impco adapter or say screw it and go for the tunnel ram?


storm
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Re: Who's run a tunnel ram and propane?

Post by storm » Fri Mar 01, 2013 4:27 am

It all comes down to what do you want. I'd personally go Oval Port heads and Tunnel Ram if I was going to use 2 425s. If I was only gonna use 1 I'd go the duel plane. I'd want torque cause that's what moves cars along and with your gearing/tyre combination you'll have a nice rev range at 0-60mph and crusing at 60mph wont have the engine screaming its heads off. The tunnel ram on LPG wont affect drivability because LPG is already a gas (vapour) so it can't seperate out of the airflow like petrol does. use it with petrol (Holleys) and you'll have fuel dropping out of suspension at low revs making it a dog to drive. Use it with EFI (either petrol or LPG) and it would be a very nice setup.

Retangular port heads are really for high revs, unless you're asking the engine to pull 6000+ RPM regularly or have them fitted to a 572 or bigger engine you'll never use their potential. The other issue is what is the tunnel ram for? Oval or rectangluar port heads? if its for Oval then go for it with oval port heads. If it is for rectangular don't even consider it for oval ports cause you end up with an air flow stalling at the mating surface due to a solid wall of metal at the top 1/4-1/3 of the port.
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

dent
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Re: Who's run a tunnel ram and propane?

Post by dent » Fri Mar 01, 2013 11:13 am

Truck is a mud/trail truck that I also DD a fair bit, so there's gonna be compromises. The tunnel ram is rectangle port the dual plane is oval, my rectangle port heads are already rebuild, so from a budget point I'm lean towards running them, im really just trying to get the most outta what I have laying around. Cruise at 100km/hr will be around 2400rpm, while the tunnel ram and rectangle ports would work great in the mud pit I'm think I might be giving to much low rpm drivability up. Curious what others have found with this type of combo.

storm
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Re: Who's run a tunnel ram and propane?

Post by storm » Fri Mar 01, 2013 2:19 pm

Then I'd be going oval and duel plane. Your revs will be limited but to me it's the best compromise.
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

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kikkegek
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Re: Who's run a tunnel ram and propane?

Post by kikkegek » Sun Mar 03, 2013 12:32 pm

32coupe on this forum had a 32 coupe (pink colored) and drives a tunnel ram.

Image

he is also on the ozrodders.com frorun and says on propane you should go by the biggest single plane intake or tunnel ram you can get your hands one.
daily: 1974 GMC 25HUNDRED Suburban - fresh rebuild 350 small block - TH350-NP203 - 4.1 end gears - IMPCO425 mixer - IMPCO model E vaporizer
project: 1977 GMC C15 Suburban - 454 big block - TH400 - gasoline
sold: 1986 Chevrolet Suburban K20 Silverado

gottago
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Location: British Columbia Canada

Re: Who's run a tunnel ram and propane?

Post by gottago » Sun Mar 03, 2013 3:27 pm

Strange as that sounds, a fellow in my vicinity who operates a tow truck claims the same thing. He has a dual four tunnel ram setup with a pair of 425 impcos. He says he ran them in progression and in tandem and that tandem gave more power and believe it or not better fuel mileage than a progressive linkage.

I've heard from a few now that intake manifolds seem to work and respond differently using propane than they do on petrol. Not sure I understand why/.

dent
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Re: Who's run a tunnel ram and propane?

Post by dent » Sun Mar 03, 2013 4:06 pm

My first small block (pre-boosted) really liked the single plane I ran on it compared to the dual plane it came with. The tunnel ram I have is a holley pro dominater, I might see if I can trade it off for a smaller street tunnel ram. Worst case if I don't like how the tunnel ram performs I can change it out.

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kikkegek
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Re: Who's run a tunnel ram and propane?

Post by kikkegek » Sun Mar 03, 2013 5:05 pm

gottago wrote: I've heard from a few now that intake manifolds seem to work and respond differently using propane than they do on petrol. Not sure I understand why/.
also a topic on it here on this forum:

viewtopic.php?f=5&t=495&start=0

1. propane expands much faster then gasoline, so needs more room to flow freely

2. propane is already a gasseous fuel, so wont "fall out of suspension" like gasoline. that is why gasoline needs high speeds and why double plenum manifolds were designed.

other info is in the link to the topic I posted and if you search the web...but you wont find a whole lot. mostly personal experience of users.

I am planning on swapping my dual plane standard manifold from my chevy small block for a Edelbrock Torker II I bought second hand this winter.

Image

I am planning on changing the cam to a Compcams XE250H
http://www.compcams.com/Technical/DynoS ... 10_001.asp

and swapping my old timing chain...so I wont be able to tell what the intake brings...but all together I expect more torque in the mid range and a little better mileage from this uprade....
daily: 1974 GMC 25HUNDRED Suburban - fresh rebuild 350 small block - TH350-NP203 - 4.1 end gears - IMPCO425 mixer - IMPCO model E vaporizer
project: 1977 GMC C15 Suburban - 454 big block - TH400 - gasoline
sold: 1986 Chevrolet Suburban K20 Silverado

dent
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Re: Who's run a tunnel ram and propane?

Post by dent » Sun Mar 03, 2013 5:19 pm

Same intake and also a very similar cam to what I ran on mine back when it was naturally aspirated. I think you will like that combo. I ran my cam straight up, advanced 2 and 4 degrees as well as retarde 2 degrees, was happiest with the cam installed straigh up.

gottago
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Re: Who's run a tunnel ram and propane?

Post by gottago » Mon Mar 04, 2013 1:29 am

I've read the intake section here before and found it a bit conflicting.
On one hand if first says,
This article seems to indicate that a dual plane is better for low RPM operation and the reasons are independent of the fuel being used.
Maybe the effects aren't that dramatic but in the next scan of Jay Stober's book, same link, he seems to be saying the open chamber tunnel ram performed better than a dual plane even at low rpm on propane.
viewtopic.php?f=5&t=495&start=0

I've been pleasantly surprised by even the older single plane manifolds when used with propane. I did pick up a used mini ram recently to try out on a sbc hopefully by late spring for all the reasons stated by everyone in all these threads. I was a bit concerned about distribution and fall out with the big plenum and the single frontal inlet but decided to try it out as the benefits may outweigh any negatives or could be dealt with by some other means. I once had to make a simple difusser to tube to go inside a tpi manifold for the same reasons. If this can be made to work well, it is a relatively cheap mini tunnel ram for the sbc. If any one has used this combo before, any tips? Otherwise will report back when together.

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kikkegek
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Re: Who's run a tunnel ram and propane?

Post by kikkegek » Mon Mar 04, 2013 1:52 am

dent wrote:Same intake and also a very similar cam to what I ran on mine back when it was naturally aspirated. I think you will like that combo. I ran my cam straight up, advanced 2 and 4 degrees as well as retarde 2 degrees, was happiest with the cam installed straigh up.
good to know! :D

what compression ratio were you running? and what transmission? and what end-gear ratio on rear axle?
daily: 1974 GMC 25HUNDRED Suburban - fresh rebuild 350 small block - TH350-NP203 - 4.1 end gears - IMPCO425 mixer - IMPCO model E vaporizer
project: 1977 GMC C15 Suburban - 454 big block - TH400 - gasoline
sold: 1986 Chevrolet Suburban K20 Silverado

dent
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Location: Fsj BC

Re: Who's run a tunnel ram and propane?

Post by dent » Mon Mar 04, 2013 12:47 pm

9 to 1 with the 305 heads that where on the engine, later I swapped on a set of 882 and dropped it down a bit. Ran the truck with a 4 speed standard, 34" tires and 3:73 gears. I later swapped in a NV4500 and ended up changing to 4:10 gears. I then put a turbo on the truck and swapped to a different motor built specifically for the turbo set-up, and ended up running a 700r4.

Dent2
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Re: Who's run a tunnel ram and propane?

Post by Dent2 » Sun Jul 21, 2013 12:03 am

So bit of an update, finally got the truck back together. Ended up runnin gen 6 vortec heads, 9.0:1 comp, 230/.520 single pattern cam, roller rockers and a port matched dual plane with an ohg 450/x-1 combo. Just dialling it in right now but I plan on also testing the dual 425 impco set up I have and then swapping in the tunnel ram for a bit of comparison. One question regarding the ohg 450, is it the thickness of the washer that affects max airflow( if at all)? And the angle of the taper that controls the amount of air at idle/ low rpm?

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kikkegek
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Re: Who's run a tunnel ram and propane?

Post by kikkegek » Fri Oct 02, 2015 2:28 am

hi Dent,

sorry to bring up that old topic, but really curious about the test with the tunnel ram compared to the dual plane.

any results back yet?

And Gottago: what is that miniram you are talking about? any pics?
daily: 1974 GMC 25HUNDRED Suburban - fresh rebuild 350 small block - TH350-NP203 - 4.1 end gears - IMPCO425 mixer - IMPCO model E vaporizer
project: 1977 GMC C15 Suburban - 454 big block - TH400 - gasoline
sold: 1986 Chevrolet Suburban K20 Silverado

Oddy
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Re: Who's run a tunnel ram and propane?

Post by Oddy » Mon Oct 05, 2015 8:11 pm

Ya im interested to. Or any of these airgap style or 2500 up manifolds ect.

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