special V8 multifuel vehicle

[cosmick]

I got as far as the first post. There's no reason for any fullsize truck to ever average less than 20 MPG when not hauling anything, even on straight gasoline. I have done 26 more than once. On diesel I've seen 34.8x for myself. Getting 40 MPG without diesel is a pipe dream unless you start with a smaller pickup then upgrade that to tow whatever, which is my own strategy. Finding a fuel at $0.80 per gallon? I can't speak to that.
IDK your idea of adequate power, but I can give you a proven recipe for 35 MPG with 200 HP, or 26 MPG with 400 HP. Either way, you have to do a Chevy rather than your Ford.

[aardvarcus]

Interesting project dusty fire walker, I will try to just stick to a few key points to try to not start an argument, looks like there is a lot of that scattered throughout this thread. Makes me sad and not want to post.

In your first post, you mentioned you wanted some constructive criticism, so I will share a few thoughts.

A few posts mention preheating fuel, I hope you are aware of the extreme danger involved with heat and any type of flammable solid/liquid/gas and proceed with extreme caution. I don’t want to see you or anyone else get hurt. I am afraid that most of us are so used to gasoline now that we forget how dangerous it is.

I am also a little worried about the engine/exhaust/intake gunking up, I hope your system doesn’t require frequent cleanings. I also hope you are setting this up in a dual fuel manner, so that you can run on straight gasoline as you work any bugs out.

I took an old truck (1991 Chevy 5.7L 2500LD) from 11MPG to 18 MPG average without even touching the engine, using careful driving and some mods. Biggest gains were from a manual transmission swap and putting appropriate (street oriented all terrain) tires on the truck.

I hope you proceed safely with your project. Good luck.

[JRMichler]

Originally Posted by dustyfirewalker

since a turbo map has a pressure ratio on the Y axis and a volume/mass flow rate on the X axis, does a draw through turbo set up cause the pressure ratio to sky rocket? there is a vacuum on the inlet of the turbo so the pressure ratio isnt on the map, right?

Well, no. Pressure ratio is pressure ratio and compressor RPM is compressor RPM. The pressure ratio is figured from the inlet absolute pressure. The inlet absolute pressure can be anything from below atmospheric (vacuum) to above atmospheric. Atmospheric pressure at sea level is 14.7 PSIA, which would be zero on a vacuum/boost gauge.

Sample calculation 1: Assume a pressure ratio of 2.00 and inlet pressure is atmospheric at sea level, or 14.7 PSIA (PSI absolute). Then the discharge (outlet) pressure is 2.0 X 14.7 = 29.4 PSIA, or 29.4 - 14.7 = 14.7 PSI of boost.

Sample calculation 2: Assume a pressure ratio of 2.00 and inlet pressure is 5.0 PSIA (about 20 In Hg vacuum). Then the discharge pressure is 2.0 X 5 = 10 PSIA. This would still be a vacuum of 14.7 - 10 = 4.7 PSI, or about 9.4 In Hg.

With 1/3 the inlet pressure, it will only need 1/3 the power to drive the compressor to the same RPM. Sizing the hot side needs to be done very carefully.

[dustyfirewalker]

JRMichler, thanks! im glad to know finally that the map is usable in vacuum. i forget 5psia IS vacuum here ha! even after calculating the pressure ratios earlier it just didnt sink in, thanks

well then i have some numbers to run, its interesting you mentioned the exhaust side of things, in Maximum Boost by corky bell he goes onto say that the compressor A/R ratio isnt as important as the exhaust. im looking at what most people put on big blocks and small blocks, seems like more than one person recommends a 1.15-1.3 for a v8, according to mr bell 1.15 is the "best compromise" for quick spool up and max power. its so neat how the exhaust flow energy is converted via turbine & compressor into intake flow energy. its just like a thumb on a water hose spraying a wheel for the exhaust, while the intake compressor "slings" the mass flow through an orifice ring around the compressor wheel, nearly at the speed of sound at times! i can just imagine the venturi effect taking place compared to a typical carb!


aardvarcus, i have REAL respect for just about anything dangerous, especially hydrocarbons. i have researched various substances to understand their properties. i have also looked into a few various vapor carbs and other ICE science. in my earlier posts i do mention possibilities of the intake charge igniting in the intake. smoky says a turbo charger will behave as a flame arrester, i have a feeling water injection being sprayed into the intake stream can also work as a flame arrester. take a look back at the videos of marcellos vapor carbs, he has an opaque nut that flickers in his intake path due to the hot vapor lighting in the intake. i am knowingly designing this with explicit emphasis on the quality of my welding and theres a real possibility something could go wrong. nothing after the turbo where the real heat is added will be made with flexible tubing, im buying premium materials and using the best available techniques to make a custom fuel and exhaust system. ill lay out my latest sketches later, and im building it very close to smokys exact design with only a few differences, i want vapors to rise, and water injection, and ill have a full sized cooling system. otherwise it should look the same as his diagrams.

ill post back when i have some good pics, peace

[dustyfirewalker]

and

H MAN

the system did start life as r12 unit. 1989 bronco 351w towing package eddie bauer. ive read that if you want to do a full r134 conversion to buy 1994 ford ac parts. i will have everything but the evaporater replaced and recharge with a huge tank of r12 we got before the price shot up. we have so much for free i would like to try it and mineral oil as the working fluid like most r12 setups. had i not messed up my condenser i would have left it alone and it should have been fine as it was hardly used since it was replaced last in 2000.

hopefully it should work great idling in desert heat, ill see

[cosmick]

Originally Posted by JRMichler

Well, no. Pressure ratio is pressure ratio and compressor RPM is compressor RPM. The pressure ratio is figured from the inlet absolute pressure. The inlet absolute pressure can be anything from below atmospheric (vacuum) to above atmospheric. Atmospheric pressure at sea level is 14.7 PSIA, which would be zero on a vacuum/boost gauge.

Sample calculation 1: Assume a pressure ratio of 2.00 and inlet pressure is atmospheric at sea level, or 14.7 PSIA (PSI absolute). Then the discharge (outlet) pressure is 2.0 X 14.7 = 29.4 PSIA, or 29.4 - 14.7 = 14.7 PSI of boost.

Sample calculation 2: Assume a pressure ratio of 2.00 and inlet pressure is 5.0 PSIA (about 20 In Hg vacuum). Then the discharge pressure is 2.0 X 5 = 10 PSIA. This would still be a vacuum of 14.7 - 10 = 4.7 PSI, or about 9.4 In Hg.

With 1/3 the inlet pressure, it will only need 1/3 the power to drive the compressor to the same RPM. Sizing the hot side needs to be done very carefully.

Reading turbo compressor maps for dummies:
1) Divide your HP by 10.
2) Find that number on the bottom of the map.
3) Mark the map on the 1 BAR line.
4) Find twice that number on the bottom.
5) Mark the map at the 2 BAR line.
6) Draw a straight line between those two marks.
7) You want that line to intersect the 70% efficiency line at the maximum safe boost pressure for your engine.
8) Now calculate your HP at your engine's TQ peak.
Repeat steps 1-6.
9) You want that to fall on the peak efficiency island. More to the right for street, more to the left for race.
When the above works, then you've found the correct compressor.
For a mildly modded 5.3L V8 or a stock 6.0L V8, you'd want a T76. For a modded 4.8L V8 or a stock 5.3L V8 you'd want a T70. For a stock 4.8L V8 you'd want a T66.

[oil pan 4]

I would say sell the R-12, the price on it is unbelievable.

I have a T76 on my diesel, could have gone bigger.

[dustyfirewalker]

hey thanks cosmick

i have seen several approaches to picking a turbo charger.
i followed the procedure you mentioned and i see that the line has a positive slope.
i have read the garret websites procedure and noticed they drew a horizontal line along the pressure ratio they wanted to run from maximum engine rpm to another point, im forgetting what value they had there but i knew that boost would rise as the mass flow increased, your method shows that, i agree more with that than a horizontal line.

and i do agree that 10 mpg sucks, but thats what the 460 efi in stock form (with shattered rings and 200k miles) with my truck and tires gave the last time i drove it before this rebuild. i feel that if 50% of the fuel burned was a flammable waste (filtered used oils) then i would be buying 1/2 as much gas. with as much as ive spent im pretty much locked into this 460. i feel like its possible to use gasified oils as fuel, and gasoline makes it start up and run better. the woodgas guys run straight woodgas with a power loss, hopefully some boost will add some ponies

oil pan,

im looking at the borg warner s400 series, i have considered a t76 aswell. im not trying to get 1/4 mile et's and i think a conservative size could yield better results. im just curious if you knew the AR ratio on the t76 you run? and other specs too thanks ill look at your page and thread(s) to see if i can find it. thanks

i look forward to getting pics up, things are looking good!

[cosmick]

Originally Posted by dustyfirewalker

hey thanks cosmick

i have seen several approaches to picking a turbo charger.
i followed the procedure you mentioned and i see that the line has a positive slope.
i have read the garret websites procedure and noticed they drew a horizontal line along the pressure ratio they wanted to run from maximum engine rpm to another point, im forgetting what value they had there but i knew that boost would rise as the mass flow increased, your method shows that, i agree more with that than a horizontal line.

and i do agree that 10 mpg sucks, but thats what the 460 efi in stock form (with shattered rings and 200k miles) with my truck and tires gave the last time i drove it before this rebuild. i feel that if 50% of the fuel burned was a flammable waste (filtered used oils) then i would be buying 1/2 as much gas. with as much as ive spent im pretty much locked into this 460. i feel like its possible to use gasified oils as fuel, and gasoline makes it start up and run better. the woodgas guys run straight woodgas with a power loss, hopefully some boost will add some ponies

oil pan,

im looking at the borg warner s400 series, i have considered a t76 aswell. im not trying to get 1/4 mile et's and i think a conservative size could yield better results. im just curious if you knew the AR ratio on the t76 you run? and other specs too thanks ill look at your page and thread(s) to see if i can find it. thanks

i look forward to getting pics up, things are looking good!

Choosing the A/R is about spool-up versus peak power. For peak power an A/R closer to 1.0 is better, but for low-RPM response the A/R should be closer to 0.70.
Fuel cost aside, since a 262-cube V6 can pull a fullsize pickup 65 MPH at 1600 RPM without lugging, and now they have 325s turning less than 1400 at 65, so your 460 should like even less RPM. Probably the only real way to get there is a 3.08:1 Sterling 10.25" or 3.07:1 Dana 70 for full-floaters, with a T56 for its 0.50:1 sixth. Then a divorced NP205, even if you're 2WD, for when you need to get a load moving.
Besides, turbos like tall gearing to pull against, especially on a big block.

[cosmick]

For cheaper fuel I'd order a kit from Propane Conversion Parts - Propane Kits, Parts, and Accessories
Combine that with 20 MPG and you'd be doing just fine. Besides, those EFI 460 intake manifolds look friendly to an Edelbrock 4-barrel if you want to dual-fuel it that way.