Turbo tuning
Turbo tuning The shop that is tuning my car has a good reputation and has done a few turbo LS1 cars in the past. My question as some one new to a turbo LS vehicle what should i be looking for and what do i need to know about tuning the LS1 before and after the tune. I have a mild set up with a TTI street kit with FMIC, meth injection, 60lb injectors, 255 fuel pump and a mild 228/234 114LSA.
Tuning turbo car with maf is not that hard to do. You dial in a safe reasonable afr and same for timing both of which are a lot different from NA. Examples pulled from a hat so dont take them to literarlly are say 16 degrees max timing with the meth injection and say afr around 11 to 1 to peak torque..11.5 to peak power..basically a lot richer than NA.
Now you can go speed density also 2 or 3 bar. That gives some more choices for the afr under boost and off boost.
Now you can go speed density also 2 or 3 bar. That gives some more choices for the afr under boost and off boost.
I talked to the shop and the guy that does there tuning today. He said the speed density tune would take a extra day and he would have to drive the car on the street. Also he said with the speed density tune i would have to retune the car when the weather gets warmer.
Ummm...... No thats what everybody thinks. swings in weather will not cause u to have to retune the car. My tune was done in august heat 89 degree day afr was 10.8 -10.4 by the end of the run. Here it is 45-60 degrees and at wot my afr is 10.7-10.3 and the car runs harder in the better air. I think elavation would cause a retune but it has to be major like florida to colorado. Your tuner is correct on the street driving to help dial it in. If your tuner is on his game speed density is the way to go. I use the 2bar of a colbalt ss its plug and tune. Speed density runs off the AIT and the MAP sensor so there will be changes to how it runs by the cpu when the weather changes.
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One big thing on my hptuners at least is you get two different tables. You have one for boost conditions and one for off boost. So you can be more like a normal afr off boost not have to just put in say 10.5 to 1 right across the board. And it knows when the car is being boosted so again better tuning. Properly setup speed density should have no cons. I am going to 3 bar this coming spring. Just ran maf for break in at very low boost.
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Verdad Gallardo Umm... con is a 100 dollar map sensor if it ever goes bad. IMHO I can say my car is stock untill I press the go peddle. My cruise Afr is 13.8 and just rolling into it the boost comes up afr goes down like 12.5 11.8 wot 10.8 or .4 It makes boosting so much funner because the car dosent load up on fuel pending the wot.
I guess it's just me but with a 60 trim turbo and a stock bottom end I wouldn't even consider going 2 bar. You lose some nice diagnostic functions like misfire detection and some inconsistency with lean start ups by going speed density. I would only recommend somebody go speed density if they are past the MAF limit which you probably wouldn't be. Tuning the MAF on that setup would be very straight forward and would be your best bet IMO. And no it won't load up at WOT before boost hits if the tuner knows what they are doing.
I guess it's just me but with a 60 trim turbo and a stock bottom end I wouldn't even consider going 2 bar. You lose some nice diagnostic functions like misfire detection and some inconsistency with lean start ups by going speed density. I would only recommend somebody go speed density if they are past the MAF limit which you probably wouldn't be. Tuning the MAF on that setup would be very straight forward and would be your best bet IMO. And no it won't load up at WOT before boost hits if the tuner knows what they are doing.
450-500 hp. The big thing I dont like about the maf tuning is beyond the range of the maf the tuner has to build the PE tables. When the maf maxes out it just dumps fuel unless there is some kind of hacking on tables beyond its range. All I know is once I went speed density my throttle response was way better cruise was way better and no stumbling when I got into boost. Also that dreaded Maf code that pops up after boosting is gone. I do know this on cold startups my car Idles just fine cold afr is 12.5 once warm 13.8. Im not sure how you would loose a misfire code by deleting the maf I read for it and could not find any info on this can u post a link or pm me the details on that. Im not a tuner Im just sharing my thoughts on speed density.
The 75mm MAF that comes on the f-bodies maxes out around 550 rwhp on a turbo car.
A lot of what people repeat is not correct and it's just something they heard somebody else say. Message forums can be a dangerous place so don't believe everything you read on the interwebz.
You are making more power than your MAF's usable range which is why it "feels" smoother in SD during boost transitions. However if it was throwing MAF codes and stumbling getting in to boost it wasn't tuned well with the MAF properly to begin with. Misfire detection automatically goes out the window in SD since SD is just a backup mode and was never meant to be run full time. Granted if you are past the MAF than speed density is the way to go regardless. No link or details are necessary, it's just the way the operating system operates. Going from a 12.5 to a 13.8 doesn't sound consistent to me and those numbers definitely aren't a 14.7 which is stoich.
All I know is once I went speed density my throttle response was way better cruise was way better and no stumbling when I got into boost. Also that dreaded Maf code that pops up after boosting is gone. I do know this on cold startups my car Idles just fine cold afr is 12.5 once warm 13.8. Im not sure how you would loose a misfire code by deleting the maf I read for it and could not find any info on this can u post a link or pm me the details on that. Im not a tuner Im just sharing my thoughts on speed density.
Last edited by NicD; Dec 8, 2008 at 11:58 PM.
yea, im at 471hp/tq on a 1 bar and the tuner said the maf is basically at its limits, he could squeeze more out of it but its not worth the time since im just going to be switching to a 2 bar, then we can up the boost 
With the cam and tune i should be in the 460~500 range on meth depending on what the tuner can do. He said he could tune the MAF and going to speed density would be unnecessary unless i wanted to. One of his biggest reasons seamed to be about the temperature change and having to have it tuned again when the weather changes. Its only a weekend car and i store her during the winter.
Joined: Jun 2004
Posts: 1,501
Likes: 7
From: Ft. Irwin, California (But Virginia is home)
NicD, can you elaborate on Misfire detection being turned off with Speed Density (1,2 or 3 Bar)? I ask because the table for Misfire is still present and able to be mdified on my 2-bar HP Tuners and the DTC for the misfire code is also still present. Usually HP Tuners shadows or deletes a parameter that can no longer be modified or is not functional.
Not saying you're wrong, I'm just curious as to why the misfire no longer works.
BTW, I'm a fan of SD applications on FI motors. My STS was only at 5PSI, but ran great with the 2-bar setup. Run my NA application with the same operating system. Works fine. Tuned it myself.
Not saying you're wrong, I'm just curious as to why the misfire no longer works.
BTW, I'm a fan of SD applications on FI motors. My STS was only at 5PSI, but ran great with the 2-bar setup. Run my NA application with the same operating system. Works fine. Tuned it myself.
The 75mm MAF that comes on the f-bodies maxes out around 550 rwhp on a turbo car.
A lot of what people repeat is not correct and it's just something they heard somebody else say. Message forums can be a dangerous place so don't believe everything you read on the interwebz.
You are making more power than your MAF's usable range which is why it "feels" smoother in SD during boost transitions. However if it was throwing MAF codes and stumbling getting in to boost it wasn't tuned well with the MAF properly to begin with. Misfire detection automatically goes out the window in SD since SD is just a backup mode and was never meant to be run full time. Granted if you are past the MAF than speed density is the way to go regardless. No link or details are necessary, it's just the way the operating system operates. Going from a 12.5 to a 13.8 doesn't sound consistent to me and those numbers definitely aren't a 14.7 which is stoich.
A lot of what people repeat is not correct and it's just something they heard somebody else say. Message forums can be a dangerous place so don't believe everything you read on the interwebz.
You are making more power than your MAF's usable range which is why it "feels" smoother in SD during boost transitions. However if it was throwing MAF codes and stumbling getting in to boost it wasn't tuned well with the MAF properly to begin with. Misfire detection automatically goes out the window in SD since SD is just a backup mode and was never meant to be run full time. Granted if you are past the MAF than speed density is the way to go regardless. No link or details are necessary, it's just the way the operating system operates. Going from a 12.5 to a 13.8 doesn't sound consistent to me and those numbers definitely aren't a 14.7 which is stoich.
NicD, can you elaborate on Misfire detection being turned off with Speed Density (1,2 or 3 Bar)? I ask because the table for Misfire is still present and able to be mdified on my 2-bar HP Tuners and the DTC for the misfire code is also still present. Usually HP Tuners shadows or deletes a parameter that can no longer be modified or is not functional.
Not saying you're wrong, I'm just curious as to why the misfire no longer works.
Not saying you're wrong, I'm just curious as to why the misfire no longer works.
Joined: Jun 2004
Posts: 1,501
Likes: 7
From: Ft. Irwin, California (But Virginia is home)
Misfire detection is automatically turned off when in SD with or without a custom OS. It's hard coded in the PCM to work that way. HP Tuners has never put shadows in or deleted a parameter that is no longer functional from their custom OS or from a normal operating system. IE the PE delay RPM in some car cals, lean cruise tables, MAF table with their custom SD operating systems, etc.
HP Tuners does shadow applications between operating systems. Load a truck or corvette tune into an operating license for a F-body to read, and all the different parameters from one operating system to the other will be shadowed grey. I do understand what you mean concerning no shadowig for applications designed for the same car, those are not shadowed. I have noted that HP Tuners will default data that it doesn't use though. An example is that on a 2-bar operating system for example, the MAF freq data is defaulted to 0 by the operating system.
Anyhow, the real question is WHY does the PCM disable misfire when in SD mode? I understand that in MAF mode a MAF fail will default to the low octane spark table for safety + the ve table values (limp mode or dumbed down Speed Density.....however you want to look at it.) So, does the PCM determine a misfire based on MAF airflow data? THAT is my question......
Appreciate th info. Didn't know this before. Just want a better understanding why it is so.