how do i calculate fuel displaced by alky

[cablebandit]

i am trying to figure out how exactly i calculate the fuel being replaced by alky. I have 8-60# injectors that get run at 73% duty cycle.....alky is 2 nozzles...m-10 and a m-15 at 70psi. What other info do i need to figure this out?

[Razor]

You have the pressure and nozzle sizing for the alky. So that one can get "figured"

The pressure is what will be needed to figure your fuel flow.

Without alcohol on race fuel what were the injectors running at?

And then with alcohol what are the injectors running at?

This will give you a ball park as well.

Typical target is 20%. So if the injectors are running 90% on race gas, then target 72% on alky.

[cablebandit]

Thanks Razor. I never ran race fuel so I cant answer that. here is the info i do know. 8 injectors...60# rated at 43.5psi. I run them at base 55psi and at wot they are at 70psi....this gets me 74% duty cycle. Is that anything you can work with?

[Razor]

The nozzles above are rated at 100 psi. To get flow rates at other pressures, use the below---

new flow rate = (Square root (new pressure / rated pressure)) x rated flow rate

So, for a nozzle rated at 10 gph @ 100 psi but actually being used at 70 psi---

new flow rate = (square root (70/100) ) x 10

new flow rate = .835 x 10

new flow rate = 8.35 gph

Now two nozzles combined 25 GPH at 70 PSI =20.875 GPH

Methanol weighs 6.5 lbs per gallon

And this equals 135.6 lb/hr (20.875 x 6.5lb/gal)= 1383 CC/min

Your fuel pressure is static 55. Thats an increase over the 43.5.

Your fuel is 542.4(480x1.13) x .73= 395.95. X 10.2= 4038.6 CC/min

Thats 29% replacement. Someone check my math... been a while :)



Gotta remember how to do the fuel flow calc...

[cablebandit]

Thanks Razor!!!! Do you think that is too much alky?

[Razor]

Thanks Razor!!!! Do you think that is too much alky?


Never :arco:

Think its time ya sprayed that sucker.. :rock:

http://forums.corvetteforum.com/showthread.php?t=1114779&forum_id=86

:marchmell

[cablebandit]

I dont want to give up the room for a n20 bottle. We normally put them in the spare tire wheel well but i have a 5 channel amp there. could put it behind the back seat but my sub box is there.....I'll just have to be slow :) weeks like the current one makes me really glad I kept a/c!!!!!!!!!! Hopefully the alky kit business is doing well for ya. It seems to be picking up on all kinds of cars. I bet i get at least 2 SERIOUS people asking questions about the alky every time i go to the track.

[Razor]

Yes amazing stuff.

Actually I was thinking about this thread today. Reason is that if the pump puts out 70 PSI and your at 15 PSI boost=55 PSI effective. Still after looking the numbers again.. comes to 30. With the higher pressure it was like 33% so the number's were off..

The couple markets i'm playing with are awesome.. the really neat thing is having shops that are willing to go the next level with this stuff.. The 4th gen kits I make use the stock WW tank in front of the radiator.

http://pg.photos.yahoo.com/ph/idoxlr8_70/album?.dir=7689&.src=ph&store=&prodid=&.done=http%3a//photos.yahoo.com/ph//my_photos

Just an FYI .. Y aget about a gallon out of it.

BTW are you running the car at Reynolds or Commerce? Or the new track in S. Ga? Reason I ask I believe the Buick event may get moved to the "other" track in S. Ga.