Learning to tune SD

[MEAN LT1]

Im not a fan of SD tuning but it does have it place when needed. I will be tuning a supercharged lt1 pretty soon and instead of waiting to see were in the rpm range it max's out the maf I rather just tune it SD and not have to worry about it. So im looking in T/C in the VE vs RPM vs MAP. Do I just rais these numbers to give more fuel? or scale the numbers in the table? Any help would be appreciated.

[JoeliusZ28]

I dont have the answer personally, but in the studying Ive been doing I have noticed this guy has some damn good info

http://redhardsupra.blogspot.com/

There is a link to a pretty thorough document on Speed Density on the right.

[Fastbird]

The VE table is your main fueling table. Higher number = higher volumetric efficiency, and thus more fuel. Lower number is lower volumetric efficiency and is less fuel. Took me a LONG time to figure that one out, and one day it just clicked. Take the "volumetric efficiency" phrase out and it's just more or less fuel using a bigger or smaller number.

Don't try to tune it off the stock O2's. Get yourself a wide band and use that for the tuning. Do LOTS of datalogging. You can also run a little program called VEMaster, but be forewarned it does NOT idle or decel tune, so you'll still have to tweak those areas on your own.

[JoeliusZ28]

Don't try to tune it off the stock O2's. Get yourself a wide band and use that for the tuning. Do LOTS of datalogging. You can also run a little program called VEMaster, but be forewarned it does NOT idle or decel tune, so you'll still have to tweak those areas on your own.
I was under the impression that the wideband data should not really be factored into the equation for idle on a cammed car because the overlap of the cam allows a lot of unburnt fuel to get through.

[Fastbird]

I was under the impression that the wideband data should not really be factored into the equation for idle on a cammed car because the overlap of the cam allows a lot of unburnt fuel to get through.

Yes and no. No being that you are correct, the overlap will have a marked effect on idle ratios. But.....tune around it. Tell the computer to look for a much leaner idle than what it should be seeing, I.E. tune the idle for around a 17 AFR for the typical bigger cammed setups. It's what I've found that worked best in my experimentation. Got it to idle nice and smooth without sputtering or going lean on tip in this way.

[JoeliusZ28]

cool cool

[edcmat-l1]

Check on CamaroZ28.com. I believe they have a tutorial on 2 bar SD tuning LT1s. If you're gonna SD tune it, may as well do a 2 bar.
Don't know your experience level, but SD tuning on these OBD1 cars is pretty hard.

[MEAN LT1]

Check on CamaroZ28.com. I believe they have a tutorial on 2 bar SD tuning LT1s. If you're gonna SD tune it, may as well do a 2 bar.
Don't know your experience level, but SD tuning on these OBD1 cars is pretty hard.

Whats hard about it?. Go in the switch table and turn on SD mode turn off the maf code the no ses light wont come on when you unplug the maf. Then go in to your constants and adjust your coolant temp to enable Closed loop. What else am i missing?

[edcmat-l1]

Whats hard about it?. Go in the switch table and turn on SD mode turn off the maf code the no ses light wont come on when you unplug the maf. Then go in to your constants and adjust your coolant temp to enable Closed loop. What else am i missing?
Um, getting the VE dialed in. SETTING IT UP, in SD ain't hard at all. Getting it dialed in is another.
Just finished a SD LT1. 92 or 3. Chip car. Moates APU made it WAY easier. Had a NASTY cam in it. I'll see if I can sound clip it.
Tuning in SD is HARD on these things to get right.
The open loop tuning to run roughly the same A/F at a variety of temps.
The power enrichment from the factory is WAY outta whack.
One of the first things I do, after locking it in Ol is set the PE to the % I want versus RPM and then don't touch it.
Then set the open loop % change to A/F versus temp.
There's alotta shit to it.
And then, And then, that doesn't even bring in to mention to more radical ones that are wanna go over 100 on the VE table, and what ya gotta do to properly map those.
Ya scale the injector flow rate and Ve til ya get the table in a workable range.
Givin up too many secrets. That's all for now.

[grn95t/a]

would mine be better in sd 2bar ed?

[edcmat-l1]

would mine be better in sd 2bar ed?
Not unless it's supercharged, or turbocharged. FI that is.
We could run yours in 1 bar SD, just like I did with Ryan's.

[Fastbird]

Um, getting the VE dialed in. SETTING IT UP, in SD ain't hard at all. Getting it dialed in is another.
Just finished a SD LT1. 92 or 3. Chip car. Moates APU made it WAY easier. Had a NASTY cam in it. I'll see if I can sound clip it.
Tuning in SD is HARD on these things to get right.
The open loop tuning to run roughly the same A/F at a variety of temps.
The power enrichment from the factory is WAY outta whack.
One of the first things I do, after locking it in Ol is set the PE to the % I want versus RPM and then don't touch it.
Then set the open loop % change to A/F versus temp.
There's alotta shit to it.
And then, And then, that doesn't even bring in to mention to more radical ones that are wanna go over 100 on the VE table, and what ya gotta do to properly map those.
Ya scale the injector flow rate and Ve til ya get the table in a workable range.
Givin up too many secrets. That's all for now.

Buncha good info here. I'm curious though.....do you ever take the lock off of open loop and let it get feedback from the various sensors (O2's most notably)??

[edcmat-l1]

Buncha good info here. I'm curious though.....do you ever take the lock off of open loop and let it get feedback from the various sensors (O2's most notably)??

Yeah, most of em I keep in closed loop. Only the real radical ones need to run in open loop.
This last one had like a 248/254 on a 106 LSA. Flat nasty cam.

[Tony Shepherd]

Ya scale the injector flow rate and Ve til ya get the table in a workable range.
.


That is a trick I have learned over the years.

[Fastbird]

Yeah, most of em I keep in closed loop. Only the real radical ones need to run in open loop.
This last one had like a 248/254 on a 106 LSA. Flat nasty cam.

:drool: NEED sound clip of that.

[edcmat-l1]

:drool: NEED sound clip of that.

I'll try and get one up later today.

[MEAN LT1]

Wow..you make it sound hard. I thought it would be easy like tuning with a maf except a little extra work. Guess not

[edcmat-l1]

Wow..you make it sound hard. I thought it would be easy like tuning with a maf except a little extra work. Guess not

There's alot to making them right.

[grn95t/a]

Not unless it's supercharged, or turbocharged. FI that is.
We could run yours in 1 bar SD, just like I did with Ryan's.

cool deal!


Yeah, most of em I keep in closed loop. Only the real radical ones need to run in open loop.
This last one had like a 248/254 on a 106 LSA. Flat nasty cam.

mines.....237/246 107 LSA

not flat nasty, but should be alittle nasty! lol! :cool:

[edcmat-l1]

mines.....237/246 107 LSA

not flat nasty, but should be alittle nasty! lol! :cool:
That oughta sound pretty nice!!!

[grn95t/a]

i hope so...;)

[JoeliusZ28]

damn that sounds like a pretty wild cam lol.

good info posted so far!

[Fixxer99TA]

Videos! We need Videos! :D

[edcmat-l1]

Videos! We need Videos! :D

Took a while to get it off the camera, and on youtube, but, here ya go......
http://ltxtech.com/forums/showthread.php?p=12063#post12063

[grn95t/a]

man that thing is awsome, bet she pulls like a beast..till 6200 anyways!

[SSSC]

bump for a good read

[Twisted Z]

Um, getting the VE dialed in. SETTING IT UP, in SD ain't hard at all. Getting it dialed in is another.
Just finished a SD LT1. 92 or 3. Chip car. Moates APU made it WAY easier. Had a NASTY cam in it. I'll see if I can sound clip it.
Tuning in SD is HARD on these things to get right.
The open loop tuning to run roughly the same A/F at a variety of temps.
The power enrichment from the factory is WAY outta whack.
One of the first things I do, after locking it in Ol is set the PE to the % I want versus RPM and then don't touch it.
Then set the open loop % change to A/F versus temp.
There's alotta shit to it.
And then, And then, that doesn't even bring in to mention to more radical ones that are wanna go over 100 on the VE table, and what ya gotta do to properly map those.
Ya scale the injector flow rate and Ve til ya get the table in a workable range.
Givin up too many secrets. That's all for now.


Damn good info here that flys in the face of what everyone will tell you! BUT TRUE!!! I can not even count the arguments I used to get in over this stuff on the Edit list. You have so many people telling you how you HAVE to do it and that changes everytime you turn around.


Again good info there ;)