Cruisin' with FAST

[ChrisCairns]

When I'm highway driving my FAST equipped T-Type I have my A/F ratio at 15.3 and my timing at 45 degrees. This is at 60 mph, 1850 to 1900 rpm. The road is mainly flat from home to work.

I'm wondering if I can go higher with the timing. (I did have my A/F ratio at 15.9 but I didn't feel comfortable so lowered it to 15.3.)

Anyone using higher timing while cruising?

 

[bruce]

I've run 48d @ 16.3 with a stock ecm, and broken 30 MPG.

The only trouble is that it puts enough heat into the motor to even drop the oil pressure 5 PSI. Coolant temp stayed the same.

Just a matter of what's more important, MPG, or long term engine life.

And if you run closed loop, a sensor can fail false rich, and lean the motor down even more.

I've taken to running about 34d at 13.7, and settling for ~25 MPG.

If your really get into it, you're looking at like having to be within 2d and .1 AFR to really find the ultra mileage settings, IMO.

Watching the VE, and TPS for a given MPH/MPG, is needed, and you have to stabilize things for like 15 mins., at each setting to let the temps stabilise for each change.

YMMV

 

[norbs]

I run 15.9 a/f and 50 degree timing as it runs cooler than 14.7 and 35 degree timing. On my egt scale meter anyway. At 70 mph my egt is 1180-1200. I have a huge oil cooler, not concerned at oil temps at all, the engine will be well worn from racing before oil temps kill it

 

[bruce]

Originally posted by norbs
I run 15.9 a/f and 50 degree timing as it runs cooler than 14.7 and 35 degree timing. On my egt scale meter anyway. At 70 mph my egt is 1180-1200. I have a huge oil cooler, not concerned at oil temps at all, the engine will be well worn from racing before oil temps kill it

Might just try the 35d, and like 13.3.
Just because your cooling the oil well, doesn't negate the heat that your putting into the piston dome, and possible damage from tip-in preignition, metal fatique, and ring failure from heat.

IMO, if your racing for money, then *hard* tuning has it's merit, but for a street car, a soft tune will let it live alot longer.

 

[ChrisCairns]

Originally posted by norbs
I run 15.9 a/f and 50 degree timing as it runs cooler than 14.7 and 35 degree timing. On my egt scale meter anyway. At 70 mph my egt is 1180-1200. I have a huge oil cooler, not concerned at oil temps at all, the engine will be well worn from racing before oil temps kill it [/QUOTE

With the timing and A/F I use presently I run 890F. at 60 mph. Give or take a few degrees. I was just watching it today.

Thanks for the info Norbs. I'll up the timing a little at a time.

 

[Superskwrl]

When you guys run the lean A/F and hi timing for MPG, are you able to maintain these settings for driving in traffic etc ie low speeds etc

 

[ChrisCairns]

I, and I assume Norbs, have the cells that FAST uses at the cruise speed with the higher A/F and timing.

When you give it more throttle it changes cells where we have different values...i.e. lower A/F and lower timing. Least that's how I do it.

 

[Superskwrl]

So, you guys have 1 program, and it is able to both performance and economy, i have done as you've described, but /cruising/driving @ 65-70mpg @ 1900 does not seem the same as driving @ 15-20mph @ 1900rpm in my car, i dont know if since my car has a manual tranny its less forgiving/more of a load etc?

 

[ChrisCairns]

Well performance starts waaaaay above 1900 rpm so the "economy" settings aren't even used by FAST other than the curser going through them for a fraction of a second.

Sorry I don't know anything about driving a standard using FAST ... maybe someone else can comment on that.

 

[norbs]

Superskwl is correct your going to get some overlapping of the ve table like that. Your just going to have to tune at the area you drive most, or go to a 2 bar map instead and pick up some resolution, but limit boost to about 18 psi.

 

[Ricky Trussell]

Thread jack is progress.....sorta applies


I have looked at a couple of .gct's lately with 3bar sensors with low boost. I was thinking how would you tune for the street like this? What psi is the limit of a two bar sensor? Looks to me you would have more cells to work with using a two bar.

PS... this would be a learning type question for me.. be gentle!

 

[norbs]

The whole idea of using the 2 bar is more cells= more resolution down low at cruise, vac and boost to 15.5 psi. The more cells the better you can tune the engine to different loads. If the boost exceeds 15 psi the ve will just be repeated in the top row for the next higher boost. Which means what ever number you progamed in will be the same for over 15 psi..So if the engine needs more fuel your out of luck, but the wide band will correct +25% so i would use it to 20 psi and not be worried

 

[Ricky Trussell]

So if I run no more than 15 psi I can use the 2bar to be able to tune for the street? That would help allot because the 3bars I looked at with low boost convinced me that street tuning would not happen. I am changing over to a turbo now and like the 2bar tuning for the street.

 

[norbs]

Its very nice to use all those cells your really can get a good response, even better idle

 

[Superskwrl]

In regards to the 3 bar VS. 2 bar, if i tune the car for race etc with 30psi and a 3 bar, is there any reason i can't take the values in the VE and spark tables and apply them in the top row's of a program with a 2 bar

i realize there would proably be some performace lost in between the 15psi to 30psi because values wouldn't be @ max, of course this is assuming VE #'s are highest, and timing is lowest of anything between @ 30

I hope this makes sense

Thanks

 

[summit]

Safer and better would be to swap MAP sensors and load the race program when racing. Much better deal if you are only talking a once a month or less deal. The FAST system actually averages the cell you are in with all the ones around it, so trying to trick it by changing the top row like that would not work very effectively. You would have to run higher numbers so it would average down to where you wanted it. Tricky proposition.

Greg Kring