FAST Impressions

[Razor]

Man I got to say this for all the negative I could think.. say.. this system is a breeze to figure out.

First time to the 1/4 mile track with a new car.. pump gas and alky, IAT's were in the 70's at 25 PSI with outside temps in the 80's.

1.501
4.481
6.979
100.11
9.173
11.029
120.41

Thing almost tunes itself.. unreal. Thanks to Cal for the shoulder and push... I really really have appreciated it.

Mid 10's on 93 octane at the Nats.. here we come.. Gotta figure out the MPH issue.. it will be soooo there.

All I can say, if you have a handle on chips.. sorta off.. this is a walk in the park.

 

[JCotton]

Simply amazing.................. now you know why I wanted to put a FAST in Tom K's car when we installed one of your alcy kits.....

 

[Razor]

You should be putting a kit on your car. I can send you some logs if you want.

See ya at the Nats

 

[norbs]

I hope you know that the alky is altering your a/f readings and there is a way to calculate it. How much alky are you injectiing?


From the innovate forum:



We've had a few reports where users could not 'nail down' their tune on the street with the LM-1. The AFR's would jump about 0.5 AFR across the WOT band even in the same weather conditions in the space of a few days. Instead of holding a tune, the engine seemed to slowly 'yodel' .

Naturally the first thing to blame was the LM-1. But it turned out that the users filled up at different gas stations, sometimes filling up on gas that had 10% ethanol mixed in.

As expected, when Schnapps is mixed with cars, things get a little complicated.

If ethanol (stoich AFR of 9) is mixed with gasoline (stoich AFR of 14.7) the resulting gas has a lower stoich AFR than 'pure' gasoline. As the fuel injection is tuned to mix a certain amount of fuel for a given amount of air, the resulting mixture would be leaner when using a fuel with lower stoich AFR.
This can be calculated:

sAFR = (%ofAdditive * sAFRadditive + (90-%ofAdditive) * sAFRgas) /100

where:
sAFR is resulting stoich AFR
%ofAdditive is amount in % of mass of additive (ethanol) mixed in
sAFRadditive is stoich AFR of additive (9 for ethanol)
sAFRgas is stoich AFR of base gasoline (14.7)

For a 10% mixture of ethanol to gasoline by mass the resulting stoich AFR is 14.13

So, for an engine that's tuned to certain AFR at a certain load and RPM on straight gas, the resulting (gasoline equivalent) AFR when running the mixture can be calculated as:

new AFR = tuned gas AFR * (gasoline stoich ratio) / blend stoich ratio

An engine tuned to 12.5 gas AFR will run at the equivalend of 13 gas AFR with a 10% ethanol blend. This is what these people were seeing.

Of course, when running in closed loop, the engine will run at 14.13 AFR instead of 14.7. O2 sensors (incl. widebands) dont measure AFR, but Lambda. Lambda is defined as actual AFR/stoich AFR. It's a ratio. In closed loop part throttle the engine is just running at Lambda 1.0, regardless of fuel. The same would be true for other Lambda values when running closed loop at WOT using a wideband. The engine would run at the tuned Lambda and everything would be fine.
Open loop systems would need to be retuned for alcohol blends though.

Regards,
Klaus

 

[Razor]

Originally posted by norbs
I hope you know that the alky is altering your a/f readings and there is a way to calculate it. How much alky are you injectiing?

Norbs, Yes I am aware. if you get crazy with the amount.. then it becomes an issue. Watching EGT, AF, and ESC while the motor is making power tells the truth.

This is one of my customers, 9.62 s/c Vette this was on Sunoco 93 + alky. Actually it is the fastest SC C5 Vette in the country. Probably the fastest ever on 93 octane.

He has over 700+ dyno pulls with an alky inj system.. most power made is at 11.8-11.9:1 on the SC Vette's he tunes. Leaner than that the motors dont detonate 12.0+ but not make any more power.

I pull about 20-25% fuel out. If I can get away with 20%.. so be it. I look for IAT temp drop and no ESC. From there watch what makes the most power on your particular application. In a few months I'll keep adding information as it pertains to this.

My runs yesterday were at 45-47% DC on 75's. I broke into the 6's 1/8 and cracked a 100 mph. I think 106-107 are in it.

On my old "chip" car, it liked low 1500's EGT's and that was mid 11's AFR. This car is running a little hotter. Just have to keep working on what AFR makes the most power .. there is no cut and dry formula except for trial and error/patience.