Chevy & GMC Vans

KH,one of the most aggravating things that happen on these forums is a O/P like me asking a question and a poster like yourself gives a honest answer.Then the O/P refutes your honest answer saying no your wrong.I am very sensitive to that and well understand what a turn off that is.We both have read about systems to buy that where more hype than fact from hydrogen to propane on demand injection.About three weeks ago I started a thread on www.clubhotrod.com about a dual fuel system.Gasoline/propane.I honestly don't know much about them and wanted to see what those guys had to say about them hoping that would give me answers.Please spend time to review the thread.

http://www.clubhotrod.com/shop-talk/481 ... oline.html

I think your going to find some valuable info from that.From the need to run a higher compression to the fact propane provides a mileage that is about only 75% of gasoline.Honestly I was disappointed in what I found.

I think your probably right about a 305 VS a 355.I do remember Darren telling us he soft peddling his 355 getting 20 to 22 MPG towing his trailer threw the mountains in Calli.He has been a hero of mine for a long long time because of that and the tune he has on that engine.

KH-honestly,I am so deep in the three vans on this project,there is no way I could just walk away.Just trust me in the fact it is in the thousands.

Your opinion I have held for yrs in high regard.I will give more thought to your suggestion of a low dollar 355 VS a 305.I want to thank you for the input bud.

Kidhauler wrote:don't want to rain on your parade but everyone i have ever seen with a 305 the first words out of their mouth was i should have got the 350.

That's always been my feeling too.

Kidhauler wrote: heck gary for the money your talking about spending on making 2 complete drivetrains and then deciding which one to use you could probably sell the van and take the motor money and buy a new ford pick up with the turbo v6 in it.

Given Gary's budget, I doubt he'd even be close to affording one of the new Fords as they are VERY spendy. But I'm sure interested in this truck/engine myself. I think one of these trucks would offer equal or better towing ability than my 99 V-10 Super Duty (which has the lowest HP/Torque of the V-10s). Sadly, this truck isn't in my budget either.

Hey gary like I said not trying to rain on your parade. I can tell you love the project and know you have been working on it for some time now getting bits and bobs for it. The propane will not make the full power of gas but the price of fuel is cheaper so that is where you save the money. But if you do go propane or natural gas then do a dual fuel set up as some small towns might not have propane and then your stuck. You can't call AAA to bring you 5 gallons of propane.

A 300-325 horse 350sbc should give you good mileage and still tear your head off when you want to stomp on the gas and crush a hemi dodge.

I will read the other thread at home tonight as I am on my I phone now.

I read thru the thread you mentioned and some great points were raised. And IMO either run propane stand-alone or not at all. Cabs and Airport limos run Propane / NG as the mileage they put on will offset the cost of the kit for a full conversion. A typical user/driver or even some couriers will never see the benefit via savings of converting their vehicle over.

The dual fuel systems were great in the late 80's and early 90's when propane was dirt cheap ( like on my old Furd van ) and the savings were noticable; but with the advancements in Fuel Injection and computer controls on newer engines the mileage these engines get cannot be matched.

If I were in your situation I would take your roller block and go 383 built for torque, with a laptop controlled throttle body injection for ease of use, and highway gears ( possibly even running one of those new double overdrive units from Gear vendors if you have an extra $5k laying around ).
For example a freinds re-worked vortec headed 383 powered El Camino ( granted not pulling a trailer ) runs a 6 speed trans with double OD and clips along at highways speeds at appx 2000 rpms in 5th and 1200 rpms in 6th at speeds of appx 70 mph. He gets much better mpg's than my equally weighted Monte SS with a .67 OD with gobs more torque ( both cars run a 3.73 rear gear ). He claims to pull 20 + mpgs easily and I don't doubt him.

I went thru the thread on the other board you posted. I still think that if you built the engine for propane the cost during the rebuild would be minimal. I know that it doesn't burn with as much bang per gallon as gasoline but with a properly built engine which is basicly better valve seats and some slightly higher compression pistons then you should get some good power. Remember that a 10% loss of power on a 330hp engine will still put out 300hp which is alot in a astrovan. Its the cost of the fuel that saves you the money not a increase in mileage. Plus the propane burns so clean the oil doesn't even get dirty. When you go to do the oil change it looks like it was just put in. The engine will last nearly forever since there is so little carbon to clog things up. The tanks are tough as hell you are not going to explode and die. If you removed the factory gas tank and went with a pure propane set up you could mount a huge tank under the side of the van. If you really wanted to go nuts you could mount the spare on the back door and put a second or third tank under the van in the rear.

One guy was posting that he can only drive for 4 hours on a tank but you have to also ask how fast is he driving and what is he towing? When I am towing my big travel trailer at 55mph (thats all the van will do) I get 12mpg so I don't last much more than 4 hours till I have to pull over for gas. Running with just the van it is good for 20-21mpg at 70mph so I am good for probably 7 hours or maybe more. I know that when I fire up in Vancouver B.C. and head south on the I.5 I go right through Washington state before I have to think about fuel I am on the far side of Portland.

The ROI(Return On Investment) is definitely a factor with propane conversions....which is too bad, cuz it's a great fuel...especially if you build a high compression engine for it...

blacknome wrote:I read thru the thread you mentioned and some great points were raised. And IMO either run propane stand-alone or not at all. Cabs and Airport limos run Propane / NG as the mileage they put on will offset the cost of the kit for a full conversion. A typical user/driver or even some couriers will never see the benefit via savings of converting their vehicle over.

The dual fuel systems were great in the late 80's and early 90's when propane was dirt cheap ( like on my old Furd van ) and the savings were noticable; but with the advancements in Fuel Injection and computer controls on newer engines the mileage these engines get cannot be matched.

If I were in your situation I would take your roller block and go 383 built for torque, with a laptop controlled throttle body injection for ease of use, and highway gears ( possibly even running one of those new double overdrive units from Gear vendors if you have an extra $5k laying around ).
For example a freinds re-worked vortec headed 383 powered El Camino ( granted not pulling a trailer ) runs a 6 speed trans with double OD and clips along at highways speeds at appx 2000 rpms in 5th and 1200 rpms in 6th at speeds of appx 70 mph. He gets much better mpg's than my equally weighted Monte SS with a .67 OD with gobs more torque ( both cars run a 3.73 rear gear ). He claims to pull 20 + mpgs easily and I don't doubt him.

I am completely convinced that a Edelbrock EFI and a Gear Vendors or TCI 6 speed would hands down put me easily into the low 20's for gas mileage.I first found out about Gear Vendors on a forum about RV's.They are expensive.For either my RV or Ole Yellar I can't afford it.The part that sucks is knowing I am paying for a 6 speed in the lost of gas mileage in small amounts because for me to come up with that kind of money all at one time isn't possible.The same thing holds true for a Edelbrock EFI.Maybe in the long run as a add-on after the van has been in service I could save up to get both.

I want to throw out this question about the Gear Vendors system.I was told one reason you don't tow in O/D is the design of the trannies that is in the M vans has a terrible fluid flow for cooling.That by running in 3th it speeds up the fluid flow helping keep it cool along with a tranny cooler.So deductive logic says you add another O/D,would that pose as a problem with the tranny fluid temp??.Does anyone know what Gear Vendors does to address that possible issue??.Got to wonder if I could tow with a mid wt trailer and the Gear Vendor O/D engage too??.

I wish I had the answer to your question Gary ! I always thought that not towing in OD was complete BS myself. Install a temp guage and pop it out of OD if the trans gets too hot and get the fluid moving thru the cooler quicker or when you are really lugging the motor and trans going uphill.

The GV(gear vendor) is after the tranny...it doesn't care what gear you're in...it just splits it as you desire.

Adding this late, but if I were doing that much conversion I would have went for a 6.2 turbo diesel. With what you are doing I would closely at gearing.