Alcohol A/F's

[sstock]

Hello,
This is the first time I've been to this site and have read many various posts and threads and have to say it is one of the most interesting message boards I have visited. The posting going on here is depicted in a very interesting and professional manner. Whew finally a UBB without petty squabbles and imaturity.
Even though, I don't own a T-Type, GN vehicle, they are very respected in my book and enjoying the Tech stuff.

I have read about the alcohol injection systems for turbo motors and was wondering if they would have similiar effects on blown motors, with boost levels in the 12lb range with similiar street Octanes?

Also, what effect does Alcohol have on Air fuel ratios during actuation of these misted systems? If my understanding is correct, Iso is a fuel with a flash so added straight without dilution should have a richening effect on the A/F's.
I realize these are generalizations, but if they are in the ballpark, I'm thinking I would like to try a tunable system on my supercharged 351 Lightning.
Thanks guys, and again thanks for the great informative reading it is a breath of fresh air.
Later
Steve

 

[turbo buicks]

hello and welcome to the board are you referring to a centrifugal or roots type blower? a centrifugal/turbo type setup seems like it would distribute the alky better than a roots type, IMO simply b/c you put the nozzle in the air flow path in a tube (small area) where as in a roots app. it would be in the manifold (large area) and therfore not distribute as evenly. im not sure fi you could/should introduce alky before the roots blower but i know you certainly shouldnt introduce alky before a centrifugal/turbo charger as it will wear the blades. 12 psi isnt a lot for an intercooled, low compression motor (my car gets 0 KR on 16 psi w/o2s perfect and 93 pump gas) but on a non intercooled roots type blower heat is more of a problem. not sure what the limits are though. i guess it all depends on your compression and psi. and yes you are correct, alky is a alternative fuel and will make cause the car to run richer and it may "bog" when the system kicks on b/c its such a sudden richening but since usually systems dont activate unless you mean to be in it, the added boost quickly leans out the richened mixture to a highr A/F ratio. this is what happened when my friend and i were tuning my car. at 15 psi the o2s were in the 830 range (rich) and the KR was 0 so we turned the boost up another pound and brought the o2s down to ~815 which was leaner and it still got 0 KR. so i got more performance from the boost and the leaner running. HTH

 

[sstock]

Thanks,
It is a centrifical type blower.
BTW, is the reason everyone here uses EGTs because the Alcohol injection will not read correct A/F's on a Horriba wideband?
Or because the EGTs are a better indicator of what is happening in the motor exhaust valve temperature wise? Sorry for the elementary school questions here.
Steve

 

[turbo buicks]

i think it was bruce that said if you use the o2 to tune get a good wideband like a horriba b/c they are more accurate. alky wont mess up the o2 readings though and wont damage the sensor. EGT is a better way to tune b/c the factory o2 sensors are reportedly not very accurate above the .700 mV range. ive seen a few examples of this being true. the hotter the EGT, the leaner it is and vice versa. the "sweet spot" for most TRs is 1550-1600 EGT. ive read that 1700 will melt the turbine wheel. an lower EGT (rich) will slow spoolup and decrease fuel economy and a higher EGT (lean) will spool up the turbo faster but also run hotter and may detonate easier. most tune to the very edge of leanness and then one step richer for that extra margin of safety in case it gets cold all of a sudden of something causes it to go lean all of a sudden, they have that protection there.

HTH

 

[Bad as L]

Also I would like to add that KR means knock retard. Steve is a Ford guy and we don't deal with knock retard cause our systems dont have that capability. I wasn't sure if Steve new this or not.

The Buick system has this wonderful ability to retard timing the minute it senses knock or detination in the engine and the Buick guys have learned to tune off of this.
Dale

 

[indysand]

Thanks for that Dale! I've seen that alot, and thought thats what KR meant, but now I know for sure.
Phil