FAST XFI 2.0 Question

John Nechiporchik · 05-02-2016, 01:08 PM

When changing the tune up mode from Speed Density to ALPHA N on the FAST XFI 2.0 system, what changes, besides the configuration parameters, are needed to facilitate the switch? The application is a 350 LT1 stock eliminator car. We are dyno testing the motor tomorrow so I would like to develop a base tune for Alpha N , open loop.
It is my understanding that the MAP sensor should be removed from the manifold and allowed to see atmosphere with the electrical connector attached and the hole in the manifold where sensor was removed should be plugged.
Is this the correct process?
Also, I have fuel and timing tables from another LT1 stocker that I can use as a starting point.
Thanks for your help.
John

Ed Wright · 05-02-2016, 04:08 PM

I have to wonder why you would want to use AlphaN, instead of Speed Density?

Greenlight · 05-02-2016, 04:37 PM

What size injectors are you using?

John Nechiporchik · 05-02-2016, 07:32 PM

Ed, Based on comments of several LT1 racers running similar combos and reading the previous threads on this site.
Greenlight, 30 Lb. injectors.

Greenlight · 05-02-2016, 07:55 PM

John,

Please check your P.M.

John Nechiporchik · 05-02-2016, 08:22 PM

Greenlight, Got the message and sent response.
Thanks,
John

pbp1 · 05-03-2016, 12:35 AM

John, I've got a two part response to your post. The first part is my professional opinion (which I have factual cases and experience to back up) but still it is an opinion and you are free to take it or leave it as such.
The 2nd part will be some explanation to better understand how alpha-n works and how changes in injector size affect tuning.
Part 1, Opinion. Some people say Alpha-N is faster, some people say Speed Density is faster, they are both wrong. The engine does not care what kind of math the ECU uses to determine how long to open the injectors, as long as the injector is held open for the right amount of time, the engine runs the same. This is a myth. I have never said that Speed Density is faster, but it is without a doubt more consistent and less work for the racer. Anybody think that Alpha-N is faster, I've got some FAST😉 LT1 and Ford Super Stockers they can try out heads up The guys I have helped don't need me to help them at every race to make changes for the weather, altitude, etc. they are cooking hamburgers and drinking beer while the Alpha-N guys are passing tune ups around like the most popular girl at the prom, or paying a tuner to come dial them back in again now that the weather has changed. I say " the guys I have helped" and not the cars I tune for a reason. A properly tuned Speed Density car does not need a "Tuner" to maintain it, it just works!

I will admit that there are some talented racers that can tune well and make their cars consistent and FAST in all conditions using Alpha-N (Cooter, Slate, etc.) but in my opinion they are just doing it the hard way. Either way, I've got respect for them and I think it is mutual.

So there is the opinion part, and you know what opinions are like? Don't agree, then no charge for the free advice😊

Now for part 2, the information. In Alpha-N, you are defining in one of two measures how long the injector is opened at a given RPM and Load, so the tune is completely relative to the injector size, brand, and fuel pressure. Change any one of those 3 variables and the tune is no longer relevant or good for the engine.
As far as what injector is needed, fuel need is just the expected BSFC x peak hp. About .4 a .43 should be close on the BSFC so for the sake of argument, 550hp x .43 = 236.5 total fuel needed. Divided by 8 injectors = 29.56 per injector at 100% duty cycle. Either I am being too generous on the HP that a 350 Lt1 stocker engine makes, or too conservative on the BSFC number, but in my opinion, 30# per hour is cutting it a little close, possibly calling for the injectors to run at 100% duty cycle (real bad idea!).
I could be off on my numbers, but 30# per hour injectors is definitely not leaving much margin for error, and remember what will happen when you get into some real good air, you will need more fuel so if you get close to 100% is bad or so-so air, you'll be SOL when you get to some good air.

Speaking of air, enough of my preaching. Here's some good advice to directly answer the question you originally asked.
Run it in Speed Density first but Datalog BPW or GPW. Get it real close to your target A/F numbers throughout with no more that 2% + or - O2 correction throughout. Put it in open loop (turn off the closed loop correction to validate your VE numbers produce an Actual A/F ratio that matches your target A/F ratios throughout the pull). Now look at the BPW or GPW numbers throughout the pull at each RPM and load point. Write these numbers down and you can plug these into your Alpha-N fuel table. It's pretty easy to start with Speed Density and go back to Alpha-N, not so much to go the other way.

Good luck!

John Nechiporchik · 05-03-2016, 10:25 AM

Thanks for your detailed reply. I agree with the process you defined for testing, validating and making crossover to ALPHA N. We will follow that process when we run on the dyno.
I have also sent you a PM.
Thanks,
John

Ed Wright · 05-03-2016, 10:36 AM

As usual, David is 100% correct. Listen to this man.

pbp1 · 05-07-2016, 08:36 PM

I forgot one talented racer and tuner who is very successful and Fast using Alpha-N. Didn't want to leave out Brina Splingaire!

05-02-2016, 01:08 PM	#1
John Nechiporchik Member Join Date: Mar 2007 Location: Grosse Ile Mi. Posts: 315 Likes: 74 Liked 12 Times in 6 Posts	FAST XFI 2.0 Question When changing the tune up mode from Speed Density to ALPHA N on the FAST XFI 2.0 system, what changes, besides the configuration parameters, are needed to facilitate the switch? The application is a 350 LT1 stock eliminator car. We are dyno testing the motor tomorrow so I would like to develop a base tune for Alpha N , open loop. It is my understanding that the MAP sensor should be removed from the manifold and allowed to see atmosphere with the electrical connector attached and the hole in the manifold where sensor was removed should be plugged. Is this the correct process? Also, I have fuel and timing tables from another LT1 stocker that I can use as a starting point. Thanks for your help. John

05-02-2016, 04:08 PM	#2
Ed Wright Veteran Member Join Date: Mar 2005 Location: Sand Springs, OK Posts: 8,132 Likes: 896 Liked 389 Times in 168 Posts	Re: FAST XFI 2.0 Question I have to wonder why you would want to use AlphaN, instead of Speed Density? __________________ Ed Wright 4156 SS/JA

05-02-2016, 04:37 PM	#3
Greenlight Member Join Date: Dec 2004 Posts: 212 Likes: 12 Liked 74 Times in 20 Posts	Re: FAST XFI 2.0 Question What size injectors are you using?

05-02-2016, 07:32 PM	#4
John Nechiporchik Member Join Date: Mar 2007 Location: Grosse Ile Mi. Posts: 315 Likes: 74 Liked 12 Times in 6 Posts	Re: FAST XFI 2.0 Question Ed, Based on comments of several LT1 racers running similar combos and reading the previous threads on this site. Greenlight, 30 Lb. injectors.

05-02-2016, 07:55 PM	#5
Greenlight Member Join Date: Dec 2004 Posts: 212 Likes: 12 Liked 74 Times in 20 Posts	Re: FAST XFI 2.0 Question John, Please check your P.M.

05-02-2016, 08:22 PM	#6
John Nechiporchik Member Join Date: Mar 2007 Location: Grosse Ile Mi. Posts: 315 Likes: 74 Liked 12 Times in 6 Posts	Re: FAST XFI 2.0 Question Greenlight, Got the message and sent response. Thanks, John

05-03-2016, 12:35 AM	#7
pbp1 Junior Member Join Date: Mar 2013 Posts: 78 Likes: 11 Liked 18 Times in 5 Posts	Re: FAST XFI 2.0 Question John, I've got a two part response to your post. The first part is my professional opinion (which I have factual cases and experience to back up) but still it is an opinion and you are free to take it or leave it as such. The 2nd part will be some explanation to better understand how alpha-n works and how changes in injector size affect tuning. Part 1, Opinion. Some people say Alpha-N is faster, some people say Speed Density is faster, they are both wrong. The engine does not care what kind of math the ECU uses to determine how long to open the injectors, as long as the injector is held open for the right amount of time, the engine runs the same. This is a myth. I have never said that Speed Density is faster, but it is without a doubt more consistent and less work for the racer. Anybody think that Alpha-N is faster, I've got some FAST😉 LT1 and Ford Super Stockers they can try out heads up The guys I have helped don't need me to help them at every race to make changes for the weather, altitude, etc. they are cooking hamburgers and drinking beer while the Alpha-N guys are passing tune ups around like the most popular girl at the prom, or paying a tuner to come dial them back in again now that the weather has changed. I say " the guys I have helped" and not the cars I tune for a reason. A properly tuned Speed Density car does not need a "Tuner" to maintain it, it just works! I will admit that there are some talented racers that can tune well and make their cars consistent and FAST in all conditions using Alpha-N (Cooter, Slate, etc.) but in my opinion they are just doing it the hard way. Either way, I've got respect for them and I think it is mutual. So there is the opinion part, and you know what opinions are like? Don't agree, then no charge for the free advice😊 Now for part 2, the information. In Alpha-N, you are defining in one of two measures how long the injector is opened at a given RPM and Load, so the tune is completely relative to the injector size, brand, and fuel pressure. Change any one of those 3 variables and the tune is no longer relevant or good for the engine. As far as what injector is needed, fuel need is just the expected BSFC x peak hp. About .4 a .43 should be close on the BSFC so for the sake of argument, 550hp x .43 = 236.5 total fuel needed. Divided by 8 injectors = 29.56 per injector at 100% duty cycle. Either I am being too generous on the HP that a 350 Lt1 stocker engine makes, or too conservative on the BSFC number, but in my opinion, 30# per hour is cutting it a little close, possibly calling for the injectors to run at 100% duty cycle (real bad idea!). I could be off on my numbers, but 30# per hour injectors is definitely not leaving much margin for error, and remember what will happen when you get into some real good air, you will need more fuel so if you get close to 100% is bad or so-so air, you'll be SOL when you get to some good air. Speaking of air, enough of my preaching. Here's some good advice to directly answer the question you originally asked. Run it in Speed Density first but Datalog BPW or GPW. Get it real close to your target A/F numbers throughout with no more that 2% + or - O2 correction throughout. Put it in open loop (turn off the closed loop correction to validate your VE numbers produce an Actual A/F ratio that matches your target A/F ratios throughout the pull). Now look at the BPW or GPW numbers throughout the pull at each RPM and load point. Write these numbers down and you can plug these into your Alpha-N fuel table. It's pretty easy to start with Speed Density and go back to Alpha-N, not so much to go the other way. Good luck!

05-03-2016, 10:25 AM	#8
John Nechiporchik Member Join Date: Mar 2007 Location: Grosse Ile Mi. Posts: 315 Likes: 74 Liked 12 Times in 6 Posts	Re: FAST XFI 2.0 Question Thanks for your detailed reply. I agree with the process you defined for testing, validating and making crossover to ALPHA N. We will follow that process when we run on the dyno. I have also sent you a PM. Thanks, John

05-03-2016, 10:36 AM	#9
Ed Wright Veteran Member Join Date: Mar 2005 Location: Sand Springs, OK Posts: 8,132 Likes: 896 Liked 389 Times in 168 Posts	Re: FAST XFI 2.0 Question As usual, David is 100% correct. Listen to this man. __________________ Ed Wright 4156 SS/JA

05-07-2016, 08:36 PM	#10
pbp1 Junior Member Join Date: Mar 2013 Posts: 78 Likes: 11 Liked 18 Times in 5 Posts	Re: FAST XFI 2.0 Question I forgot one talented racer and tuner who is very successful and Fast using Alpha-N. Didn't want to leave out Brina Splingaire!