Gallon p. minute on blown PM engine

Marco, it depends on which cam you are using but you need 5.5 to 5.8 gpm while on the Two Step. The if you divide the GPM by the amount of boost at any one rpm you need to be safe on start out .33 to .34 gpm per one pound of boost. That should be at any point during the run the you can read the plugs according to my article. http://www.dragstuff.com/techarticles/reading-alcohol-spark-plugs.html That is a pretty good ET so far so I believe you are close so how much burn on your plugs now? If you want to see a picture of a plug with the right color then email me at Mike.c@mindspring.com

 

Nemo you need to email me at Mike.c@mindspring.com

 

When you say your plugs are colored 3/4s of the way what color do you mean? Can you email me picture of your plugs to mike.c@mindspring.com. I will also email back some pictures of plugs. How are you getting AFR?

I need to see just plugs with just one run on them. It also helps to clean them off with brake cleaner

 

With that program I would use the plug readings to get the mixture correct then feed the data into the program and read the AFR. Then whatever it reads rich or lean is the reference for your combination. What is your GPM to Boost right now and what is the displacement of your motor?

 

Keep in mind the .33 gal is just a reference. There are a number of other factors that may require your combination to have more or less. For instance if you have a bunch of head temp, you are going to need more fuel to cool it off than a combination that has a cool head. I have seen different camshafts want something different for fuel. Also, the boost transducer itself is a major variable. For instance there's a story about two TAFC teams several years ago with identical engine combinations. One team's blower showed 3 more lbs of boost on the graph. Well the team with the "good" blower lost first round and let the other team try their blower, only to see no difference in performance and the boost graph was nearly identical to their blower. On a side note from the original topic - the best boost gauge is the speed scoreboard!

 

You are right it is not accurate but it will put you in the ballpark plus or minus maybe 2 then you can fine tune from there using plug readings. The biggest factor in if it is going to be .32 or .35 is the camshaft. The camshaft also causes the amount of boost to change. You still need to tune your motor using plug readings.

 

No it does not include the Two Step. You say .3 and that us lean. You want up around .34 to start out with the read your plugs and go from there. Your on the Two Step sounds pretty good.

 

Boost changes with rpm and believe it or not the gallons per pound of boost will remain fairly constant providing you are not turning leanouts on or off. This is not a theory and you can make a Racepak math channel that divides the GPM by boost and watch it remain constant on the graph. Or you can do a RacePak ASCII Text print out of rpm, boost and GPM and divide it out yourself. Also how can you make 46 lbs of boost at 8000 rpm and also make 46 lbs of boost at 9600 rpm.