fuelsystem for blown 340 ?

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duster340

street racer
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whats your recomendations on fuelsystem for my 340
im putting toghether a stock stroke 340 with 8.1-1 compresion running a lysholmtwinscew that is capable of about 15psi of boost
i have an old 1050 holley dominator i dont know the listnumber but its for a singelcarb N/A application in the firstplace
.570/.576 242/248degre duration at .050lift solid roller.
ported edelbrock heads
should make some stupid power? :-D

i also have a fuelcell in the car so big fuellines is not a problem
i have a carter mechanical highvolume pump in good shape but that may be to small for this?

what size lines and what kind of fuelpump would you recomend? im trying to avoid a holley bluue pump since they all seems to hate me

its just a pumpgas streetcar that will see some tracktime from time to time so i want to keep it reliable
 
I'm running 93 oct pump gas with a BG 220 pump into a #8 line to a pair of Demon 750 double pump blower carbs, then through a BG regulator and back to the cell though a #10 line and it works great on my 416
 
One or two walbro gls-392 pumps are all that is needed (inexpensive and reliable). A rising rate (1:1) regulator and a return line from the regulator back to the tank.
 
Shaker223 said:
One or two walbro gls-392 pumps are all that is needed (inexpensive and reliable). A rising rate (1:1) regulator and a return line from the regulator back to the tank.
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x2...these pumps are awesome for what they are...run two in a y and your good to go
 
KP said:
If I can ask, why such a large carb?
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blower has a dominator flange and a 750 seems to small for a draw thru aplication atleast thats how im thinking also dominators are pretty hard to come by over here so i was just happy i got one that wasnt bigger for a reasonable price



ok will start doing some reserch on where to get a warlboro pump or two, they dont seem to be impossible to get over here:) and BG pumps are pretty expensive here:(
 
you can buy the walbro pumps for like 99.00 each right off of ebay, and that is with free shipping. two walbro 255lph would do the job. i use them in all my mitsubishi turbo cars
 
duster340 said:
blower has a dominator flange and a 750 seems to small for a draw thru aplication atleast thats how im thinking also dominators are pretty hard to come by over here so i was just happy i got one that wasnt bigger for a reasonable price



ok will start doing some reserch on where to get a warlboro pump or two, they dont seem to be impossible to get over here:) and BG pumps are pretty expensive here:(
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Blow thru carb is the way to go these days not draw thru. There are guys making over 1000hp with the 750cfm carbs.

Make sure the GSL392 is the high pressure unit.

Also, you can have one support your normal driving and the second come on at a specified boost level. I'm told the "off" pump will be fine in the off position and act as a dead head and not allow fuel to push past it.
 
340plot said:
you can buy the walbro pumps for like 99.00 each right off of ebay, and that is with free shipping. two walbro 255lph would do the job. i use them in all my mitsubishi turbo cars
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watch who you buy them from on ebay though as there are quite a few guys selling walbro copies as walbro's and they break very soon...id spend the extra 20 bucks and get them from summit or another trusted vendor
 
Shaker223 said:
Blow thru carb is the way to go these days not draw thru. There are guys making over 1000hp with the 750cfm carbs.

Make sure the GSL392 is the high pressure unit.

Also, you can have one support your normal driving and the second come on at a specified boost level. I'm told the "off" pump will be fine in the off position and act as a dead head and not allow fuel to push past it.
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maybe but the few twinscrew blown cars i know of runs real hard and the twinscrew just isnt set up for blow thru..

have found a few sources for warlbro pumps now that are reputable, very good ide to run one pump during normal driving and another turning on at a set boost preasure :)
 
I don't know much about the warlbro pumps so I can't say much about them but, make sure you talk to BDS or Dyers and see if they would recommend them on a blower setup.

You need high volume, not high pressure! high pressure is good with injection but not with carburetors and definitely not for a blower setup. The higher pressure doesn't get the fuel to flow in the carb any better or faster and when that blower is sucking more air, you better have the volume of fuel needed to supply it or you may end up exploding the engine from lack of fuel. High pressure in this application isn't going to do anything other than cause needle and seat issues and leaking. I'm only running 4.5 - 5 pounds of fuel pressure but my pump is capable of a lot of volume and I have the fuel line to back it up.



KP said:
If I can ask, why such a large carb?
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Because of the blower. If anything, 1050 cfm may not be enough. I'm running dual 750 DP Demon blower carbs with a 671 and when I bought them I was going to be running a 340 and not the 416 I ended up building my carbs are a bit small now for the cubic inches but I don't have the boost I originally was going to run so it works out ok.

When you have a blower you can be flowing upwards of 10 times as much air of a naturally aspirated engine depending on your drive and boost and you need a carburation set up and fuel delivery system that is capable of keeping up or you could starve the engine of fuel or choke it at higher rpm's.


One thing though duster340, I'm not sure what the volume of your blower is but I wouldn't try and run the full boost capabilities of the blower unless you have a bullet proof lower end and running high octane fuel. 15 pounds of boost with 8-1 compression can give you upwards of a 16-1 final compression ratio depending on the volume of the blower, 12.4-1 final compression is max for 93 pump gas and is a lot for street use.

I have 8.5-1 compression in the engine with 6.5 pounds of boost and that is right at 12.5-1 final compression. If memory serves me correctly, 8 pounds of boost would give you around 12.4 final compression with 8-1 compression in the engine.
 
the walbros are used by the blow through guys all the time with great success
 
Blownfish said:
I don't know much about the warlbro pumps so I can't say much about them but, make sure you talk to BDS or Dyers and see if they would recommend them on a blower setup.

You need high volume, not high pressure! high pressure is good with injection but not with carburetors and definitely not for a blower setup. The higher pressure doesn't get the fuel to flow in the carb any better or faster and when that blower is sucking more air, you better have the volume of fuel needed to supply it or you may end up exploding the engine from lack of fuel. High pressure in this application isn't going to do anything other than cause needle and seat issues and leaking. I'm only running 4.5 - 5 pounds of fuel pressure but my pump is capable of a lot of volume and I have the fuel line to back it up.






Because of the blower. If anything, 1050 cfm may not be enough. I'm running dual 750 DP Demon blower carbs with a 671 and when I bought them I was going to be running a 340 and not the 416 I ended up building my carbs are a bit small now for the cubic inches but I don't have the boost I originally was going to run so it works out ok.

When you have a blower you can be flowing upwards of 10 times as much air of a naturally aspirated engine depending on your drive and boost and you need a carburation set up and fuel delivery system that is capable of keeping up or you could starve the engine of fuel or choke it at higher rpm's.


One thing though duster340, I'm not sure what the volume of your blower is but I wouldn't try and run the full boost capabilities of the blower unless you have a bullet proof lower end and running high octane fuel. 15 pounds of boost with 8-1 compression can give you upwards of a 16-1 final compression ratio depending on the volume of the blower, 12.4-1 final compression is max for 93 pump gas and is a lot for street use.

I have 8.5-1 compression in the engine with 6.5 pounds of boost and that is right at 12.5-1 final compression. If memory serves me correctly, 8 pounds of boost would give you around 12.4 final compression with 8-1 compression in the engine.
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thanks thats a very informative post :read2:


the blower is a 3.3liter and it will survive spinning alitle over 13000rpm
honestly i know my shortblock isnt as strong as i would like it to be, the mayor week point as i see it is the stock block, the crank is a stock forged one and i have eagle H-beams, may not be the strongest out there but its what i can afford and atleast stronger than my old stock rods, pistons are some slightly milled down trws, the tops of them are thick enough that i wont worry about them even if there is no quench what so ever left.
i will try to keep boost down at a reasonable level as you advice.
there is one good point with the twinscrews atleast they dont make alot of heat from what little information i have found about them so i hope that will give me some margain against detonation at least :)

well so big lines and fuel with moderat preasure seems to be the way to go :)
 
I would at least install a girdle, that will strengthen the lower end quite a bit.

I would do some research on the blower you are using and ask around to see what issues others have had with the same setup and what fuel delivery and boost they are running. One thing I've learned while setting mine up is you can ask 20 different people running the same thing and come up with 20 different ways to set it up and 50 different problems, I did this and just used the comments and help that made the most sense as well as reading several different books on superscharging. There's several good informative ones out there, BDS has a supercharging handbook. There's also one by Pat Ganahl called Street Supercharging and I have an older one from the 70's called Super Power, a do it yourself guide to: turbocharging, supercharger, fuel injection and Nitrous-oxide. You can also probably find something on ebay.
 
thanks blownfish! im looking around for a girdle and have found some info on where to find them localy now:)

these blowers are not very comon even here where they are made unfortionaly and the few i know of are on dedicated racecars that have little similaritys with my "mild" streetcar but i will try to talk with the ones i can talk to..
yup your so right on the fact that its hopeless to ask around to much there is just as many opinions as there is people but i learn from all the advice i get and get a bigger picture:) and i have the streetsupercharging book and have read it a few times from end to end so to speak :)

thanks im learning alitle here:)
 
duster340, just out of curiosity, let us know what kind of pricing you find for the girdles over there. I have to pick one up as well and was curious in comparing pricing and quality.
 
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