Blown Gas - What Fuel?

[Yeager]

Ok, I have a 454-9.5:1 (so the old owner says) - 25% overdriven (approx. 18lbs of boost) w/ (2) 850's

Any ideas on what gas to run? I want gas, no methanol. I may just slow the blower down.....

(I do have a Sunoco connection.)

This will be a lake cruiser so I'm thinkin I should just mellow it out.....:( maybe 2% over?

Ideas? Thoughts? Past experiance? Fire Away!

Thanks

[Terrible toy]

That's a lot of boost and compression. The formula for finding EC ratio is ((boost psi / 14.7) + 1) x motor compression = effective compression. I ran your numbers and it comes out 21 to 1. I think that would be a miserable SOB for cruising around.

My guess is to stay around 10lbs of boost at your static CR. Any thing much lower then that amount of boost and I don't think it would be worth having a blower.

I am definitely not an expert on street or lake cruiser type blower set ups. This is my best guess from racing those things. I'm sure there are some members here who have more knowledge about your question then I. I would like to see how far off I am with this advice.

[Flatmvn]

I am running a 671 on a 30 over 454 with a static of 8.3 to 1, Blower boost is 12lbs ( 10% over drive) equals a final compression ratio of 14.5 to 1 and I am running 110 octane SUNOCO.

Like TT said your final comes out to about 21.1 to 1 according to BDS Blower Boost Chart. I would say you need at least 116 or 118 to run the combo you have.

Here is a link to there chart for your reference.

http://www.blowerdriveservice.com/techcharts.php


Louis

[wagspe208]

You have quite a lot of compression for river cruising gas application. Good luck. Set timing at 32 degrees and forget it. You will need prett damn good gas for 9.5 anf 10 pounds of boost.
You said +2%. Boost is a function of blower size, overdrive, and cam overlap. If it is a gas cam, it will have more overlap than an alcohol cam. Tons of overlap makes less boost. Wide lobes make more cylinder pressure. Cylinder pressure will dictate what gas you can get by with.
What the hell do I know?
Do you have a boost guage?
Start out at 6 to 8 pounds with good gas and work forward or back from there. More power--more boost. Cheaper gas--less boost. I say 6 to 8 because that should be a safe range. Start at 10 with 9.5 and gas is more of a factor..and tuneup.
Wags

[Terrible toy]

Wags or Louis, at what point do you hit a point of diminishing return when you lower the boost or compression ratio? If you lower the compression ratio too much your off idle performance would suck or if you get too low on the boost the energy to turn the rotors starts to overtake the performance gain. Any idea where those lines cross?

Also, how much boost can stock or unblown type pistons, pins, high top ring placement, rods and crank take before causing probs? I know the parts in my blown alcohol car were tanks compared to the unblown boat stuff.

[Moneypit]

Did I read that right? 21:1 compression in a CHEVY block, that could, well, could maybe, actually live @ 21:1 for how many seconds??????? Is this an Art Anderson engineered block? (This is one of many angles Art has over Chuck Norris, Magic BBC blocks, with anti gravity zombanga main caps...The centrifically actavated magnetic ones...Shhhhh, don't let the jet guys know.........OR we'll see 240MPH jets on Ebait............I smell a rat, a well endowed , big fockin' rat........

[Yeager]

Thanks for the ideas. I do not have a boost gauge on it. I think I'll bolt one on to see whats its doing. (I got the boost guess off the BDS site.) I'm thinking a tune up like Louis mentiond will be good. I can get race gas at good prices.

I have the timing @ 32 degrees now.

Unfortunatley, the guy I bought the boat from didnt know much about his motor combo. So I have no clue what cam is in it. The only thing i do know is its a roller motor that probably has one season left on it. The heads have a decent port job, and the manifold could use some work. And it was running way fat. So I bumped the heat range up a couple steps and probably going to lean it out. (After I change the pullys;)) I'll go through it this winter (hopefully not sooner)

I have built a bunch of motors, (Drag Racing) but this is my first adventure with blowers. (and V-Drives) so I appreciate your comments.

Thanks,
Mark

[RiverRacer]

With that kind of compression and boost, you best take advantage of the good race gas prices!..;)

And if you don't know anything about this motor, I highly suggest tearing it down and check everything and measure it up, could save a ton of $$$$$$$$$$ and grief!...

[Flatmvn]

Mark,

If you can give me some numbers we might be able to tell what boost you are running with out the guage also can tell what % over drive you have.

Blower size
Pulley sizes (how many teeth on each one) they should be marked.
What pullies are they 8mm, 1/2, or 14mm
If you don't know what size blower measure the main case length
671 is 15in.
871 is 16in.
Also if you can do a compression test it will give us a little idea what the static compression is.
Propper way to do it, Pull ALL spark plugs, disconect ignition source, open throttles all the way, crank engine 3 pumps on guage, take reading and tell me the average of all 8 cylinders.


Louis

[Flatmvn]

Wags or Louis, at what point do you hit a point of diminishing return when you lower the boost or compression ratio? If you lower the compression ratio too much your off idle performance would suck or if you get too low on the boost the energy to turn the rotors starts to overtake the performance gain. Any idea where those lines cross?

Also, how much boost can stock or unblown type pistons, pins, high top ring placement, rods and crank take before causing probs? I know the parts in my blown alcohol car were tanks compared to the unblown boat stuff.

Well you have to brake it down in to sections on blown motors.

Start with Static compression ratio. the lower your static compression the more bottom end and mid rage you have. (of course this varies by cam profile also).
The higher the static comp ratio the more mid to top end power you build. ( Once again also varies by cam profile also).
As for efficiency of the super charger this has so many variables that it is not even funny. It all depends on the size of the blower and the prep stage of it. Depending on these factors every supercharger has a limit to where it is just not efficient any more. They are limited to speed and boost. In other words,You just cant keep spinning a supercharger faster they will only go so far. There is so many other variables that this could go on for days. This is why when you build Supercharged Motor you really need to do your home work and have a plan of what you expect it to do.

As for you question about stock parts what they will take is very little. The safe range for stock parts is 3 to 5 lbs of boost safely.
Forged pistons, ARP rod bolts, Dimple rods and a steel crank you can run 7 to 10 lbs boost safely and up to 12 if you live dangerously. (I do ):D

Allot of this is my opinion and may not be supported by facts. Some of it is from experience (which is very little) and the rest well I guessed. :D If I am wrong I am sure some one will correct me, but you have to remember everyone is different and there are a million ways to do something and achieve the same result.

Hope that answered some of your questions. Any more than that I may not have the answers.

Louis

[Moneypit]

All the above, and.....002 valve lash, either way, can also alter the power curve. And as mentioned, they're all a little different......21:1 aint happening....MP

[Yeager]

Louis, Thanks for all the info.

34 top pulley - 44 bottom - 1/2" - 6-71

I will do a compression test tonight.

I'm thinking of going 5% over and run race gas. I'll get you the compression test average tonight.

Thanks!

[Flatmvn]

Louis, Thanks for all the info.

34 top pulley - 44 bottom - 1/2" - 6-71

I will do a compression test tonight.

I'm thinking of going 5% over and run race gas. I'll get you the compression test average tonight.

Thanks!

Well according to BDS they don't make a 44 tooth bottom pulley in 1/2 or 8mm closest I can come to is 41. They make the 34 top but the pulley's might be from another manufacture.

Based on BDS drive chart every tooth is 3% on the lower pulley. So if you add 3% for every tooth after 41 you will add 9% for a 44 tooth bottom pulley. With a 34 and a 44 pulley it is 20% over, add 9% to that and you are at 29% over.

Any questions so far class.:D

On to the Supercharger now. There are 2 different 671's. There is a Small rotor and a Large rotor from BDS I am not sure about other Manufactures. Also there are s at least 4 stage of superchargers. The info I am giving is for Stage 1 and 2 blowers and will still very for each engine. Boost reading are base on a wide open throttle, under load at 6000 rpm. Keeping all this in mind.

Small rotor 671 on a 454 @ 29% = 10lbs boost.
Large rotor 671 on a 454 @ 29% = 20lbs boost.
Based on these numbers and if your engine has a static compression of 9.5 to 1 your final compression at 6000 rpm will be around,

@ 10lbs boost = 16 to 1 final
@ 20lbs boost = 22.4 to 1 final

Based on this info I think you really need to find out which blower you have. The Small rotor has a 3/4" thick case and the large has a 1/2" thick case. I don't know how you would measure this with out disassembly. You might want to call BDS and ask them if there is away to figure it out with out taking it apart.

I am with Ray I really can't see that engine having 22 to 1 compression.

Hope I am helping you out.

Louis

[Yeager]

When I orignally started this thread I was off on the tooth count. I counted the teeth (4) times last night to double check. This boat was build in the late 70's so who knows who built the lower pulley. The Blower is a Mooneyham. (are they still in business?)

After reading all of your info, I'm thinking this thing is only making 10lbs of boost. The last owner drove this boat with pump gas when "cruising" and race gas when he was stepping on it. I agree, this thing would be dead very quickly at 22:1.

The dude I bought it from had this boat for 12 years, and I really dont think he ever changed components, just rebuilt it from time to time.

So if I leave it........Do I run 110,112 or 114? @ 16:1

Also, this boat will rarely see WOT. If it does it will be a short rip.

Thanks again!
Mark

[Terrible toy]

Gene Mooneyham, one of the very best. He passed away a few months ago after a long career starting in the early days of drag racing and after that building blowers. Super nice guy, loved boat racers...would invite you to the top of his motorhome and hold court on all things racing. It was always a good idea to listen.

[Terrible toy]

And yes, they are still in business.

[Flatmvn]

Yes Mooneyham is still in business if you call them they might be able to tell what blower you have, some times companys stamp them to identify them. They might be able to tell you where the markings are. They are Located in Upland CA. Here is a link to there web site,

http://www.mooneyham-blowers.com/

If you leave it the way it is I wouls start with 110. Take it out run it abit check your plugs very carefully and see what they look like. If they have good color ( nice grey color its race gas) and there are no signs of meltdown ( little tiny black specs on porcelyn of plug) I would runn it. I would check my Plugs after every outing for a while just to keep an eye on things.


Louis

[hydroguy]

The heck with the 110 octane, you've got a blower motor with high compression, what are you going to save a couple of bucks maybe as opposed to expensive knock? Get with the program and use 116 octane. That eliminates one potential problem right off the bat then check the plugs etc as mentioned by Flatmvn.

[RiverRacer]

The heck with the 110 octane, you've got a blower motor with high compression, what are you going to save a couple of bucks maybe as opposed to expensive knock? Get with the program and use 116 octane. That eliminates one potential problem right off the bat then check the plugs etc as mentioned by Flatmvn.

Ditto!.....

[RiverRacer]

Gene Mooneyham, one of the very best.

He was the "BEST" hands down!..:cool:

[shooter2]

And with the 116 octane the motor will make more power. LOL That always makse me laugh. A guy says he is running race fuel today in his stock civic so it goes faster. Always run the best fuel you can, sound like you have a pretty hot motor there so good fuel is cheap insurance

[RiverRacer]

Race gas needs high compression to work, in a low compression deal it will actually hurt performance, sounds funny but with an 8.5 to 1 motor 87 octane skunk piss will make more power than race gas!..

[wagspe208]

44 tooth pulleys are of course made. I have a 43 and a 44...maybe a 42...don't remember.
As far as calculating boost without a gauge..wow! How do you have any idea of what condition the blower is in?
As I said...I am not very educated in blowers. Just wondering. Everything I read in any catalog may apply to Brand A pieces...Brand B may and will be totally different.
Wags

[Yeager]

I'll run the 116 to start. I have 20 gallons in the garage.

Thanks again everone for your info.

Hope to actully meet some of you guys on the water this year.

Wags- I dont have any idea on the blower. I will this winter. (Its gonna get a tune-up) I'm also going to put a boost gauge in it.

Mark

[RiverRacer]

You could always step up the compression and run alky!.:D

[Terrible toy]

You could always step up the compression and run alky!.:D

In my opinion alcohol is much more forgiving then gas with superchargers. I've never built or tuned a blown gas engine, but drove them for other boat owners. Nasty, bite your ass, things on gas if you didn't have everything just perfect.

My one experience building a blown engine was for an alcohol dragster. I used a Kuhl high helix mag 14.71 on it. Kuhl put on a one day training seminar for customers. They taught you maintenance, tuning, and how to tear down, re strip and reassemble the blower. That thing would produce 38 lbs of boost and the car ran great right out of the box. Point being, there is nothing like getting a little training from the experts.

Yep, that car ran good. But, even on alcohol, blowers can ruin your day. Feeling very confident after extensive testing went to the first race. On a qualifying pass I didn't shift out of low gear on time, hung a valve...BOOM! New blower, burst plate, aluminum bolts, parachutes, and repaired sheet metal intake manifold later it was ready to go again. At the very next race a rod came apart, probably stressed in the blower explosion. Out of money, that ended my TAD racing career. Point being, even with the best equipment and training, roots type blowers full of explosive fuel and under pressure can bite ya.

[Flatmvn]

Wags you are right about calculating with out a guage. We are only guessing using generic charts provided by BDS. There is no way to be sure unless you put a guage on it. Like I said earlier there are so many variables that it isn't even funny. All the info posted is just basic. It is still a wild ass guess as to what he really has.

Louis

[RiverRacer]

In my opinion alcohol is much more forgiving then gas with superchargers.

Bill, Alky is more forgiving in any way wether it's blown or N/A, just pour it in and it runs, you can run it fat enough to fill the oil pan(which most do)and it still runs, BUT air fuel ratio is air fuel ratio no matter what fuel you run, and only when you're on the tune up that it will really "run"!. The cool thing with gas is that you don't have to fill the oil pan with fuel to find out your fat, it shows you right away with the smoke!.. As far as melt down goes, gas and Alky both will do the same thing, or any fuel for that matter if you lean it out too much!.. But if you want power Alky is the way to go, as long as it's on the tune up!..

[Yeager]

No Alky here. No worries. I like gas.... I can see it burn, and I dont want have to carry 55 gallons of fuel to go out for a weekend. ;) If I get the point I want to go really fast, I'll build somthing different.

This boat was alky at one time. It was also water injected. (I took it off)

I'll let you know how it goes.

Mark

[RiverRacer]

No Alky here. No worries. I like gas.... I can see it burn, and I dont want have to carry 55 gallons of fuel to go out for a weekend. ;) If I get the point I want to go really fast, I'll build somthing different.

This boat was alky at one time. It was also water injected. (I took it off)

I'll let you know how it goes.

Mark

And at today's prices Alky is about as much as gas and you use twice as much, so gas is actually cheaper to run now!..

[Terrible toy]

And at today's prices Alky is about as much as gas and you use twice as much, so gas is actually cheaper to run now!..

I agree, for a fun boat gas is the only way to go. On top of the things you mention a real problem with alcohol is the corrosion factor on aluminum. Any where it touches raw metal or where anodizing has worn off will be powder in short order.

For racing, if the rules permit it, alcohol is great, it burns cool and yet has bucu energy. You can idle a high cylinder pressure alky motor for ever and it won't get hot. I think that is one of the reasons blown gas motors are so touchy. Between the engine building heat and the blower building heat you've got a load of hot fuel in the blower looking to ruin your day.

[RiverRacer]

I agree, for a fun boat gas is the only way to go. On top of the things you mention a real problem with alcohol is the corrosion factor on aluminum. Any where it touches raw metal or where anodizing has worn off will be powder in short order.

For racing, if the rules permit it, alcohol is great, it burns cool and yet has bucu energy. You can idle a high cylinder pressure alky motor for ever and it won't get hot. I think that is one of the reasons blown gas motors are so touchy. Between the engine building heat and the blower building heat you've got a load of hot fuel in the blower looking to ruin your day.

Corrosion factor is not a problem anymore with Top Lube in it, also RedLine has some pretty good stuff, I had the PS52 boat here and it sat outside in 110 weather for a couple of months and was no different than having gas in it!..

[Norseman]

CHEAP Alcohol??

Kick the oil habit and make your own ethanol

Kick the oil habit with a make-your-own ethanol kit
By Timothy Gardner, Reuters
Thu May 8, 6:00 PM EDT
A new company hopes drivers will kick the oil habit by brewing ethanol at home that won't spike food prices.

E-Fuel Corp unveiled on Thursday the "MicroFueler" touting it as the world's first machine that allows homeowners to make their own ethanol and pump the brew directly into their cars.

The portable unit that sells for $10,000 resembles a gasoline station pump and nozzle -- minus the slot for a credit card, or the digital "SALE" numbers that whir ever faster at retail pumps as global demand pushes fuel prices to record levels.

Instead of tapping gasoline from an underground tank, the pump's back end plugs into home power and water supplies to make ethanol for as little as $1 a gallon (3.8 liters), according to E-Fuel.

The company says one of the machine's top selling points is its sweet tooth. It ferments fuel from sugar, the price of which is historically cheap as global supplies are glutted.

That means it avoids the Achilles heel of today's U.S. ethanol system -- reliance on corn -- which has been blamed for helping to spike global food prices.

"There's no mother in America crying that their kids aren't getting enough sugar," Tom Quinn, CEO and founder of E-Fuel said in an interview.

Regular table sugar alone is too expensive, so E-Fuels says it will link customers to cheaper surplus supplies, including inedible sugar from Mexico that sells at a fraction of the price. It also hopes to get users to help pay for feedstock by selling carbon credits for using the machine, since making ethanol from sugar emits fewer greenhouse gases than making it from corn.

"We will break the traditional ethanol system," said Quinn a California computer and computer games inventor, who has bankrolled the company with what he calls "millions, but not multimillion" of dollars.

He said despite the steep upfront costs, the machines will pay for themselves quickly. For a two-car family that drives about 34,500 miles a year, the MicroFueler will pay for itself in less than two years, assuming average gasoline prices of $3.60 per gallon, the company said. The unit makes up to 35 gallons (132 liters) of 100 percent ethanol per week.

Others are not so sure that the MicroFueler is a good investment.

"I doubt it will work," said David Pimental, a professor at Cornell University who has studied the economics of ethanol for decades. He said the history of the fuel has been one of moving to greater and greater scales to increase the efficiencies of making the fuel.

E-Fuel says the machine is efficient in a way that big ethanol plants aren't because it removes water from the fuel with special fine filters that reduce the fuel costs of distilling the water out.

(Reporting by Timothy Gardner, editing by Marguerita Choy)

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