6psi untuned...everyone read
10-25-2009, 09:13 PM
#1
Banned
SL Member
Thread Starter
Join Date: Nov 2007
Location: Germantown, MD
Posts: 2,893
6psi untuned...everyone read
well after finally getting my wideband(thanks jon) ive noticed that cruising around on a turbokit untunned the ecu does well with, now in wot and full boost, i was at 15.7afr and 16......
CONCLUSION:
unless your running a 16g do not go 6psi untuned youll blow ur ish up
CONCLUSION:
unless your running a 16g do not go 6psi untuned youll blow ur ish up
10-25-2009, 09:51 PM
#4
Senior Member
SL Member
Join Date: Jul 2007
Location: Milwaukee Wisconsin USA
Posts: 627
Ive been on a custom kit running a T3T04E garrett turbo at .4bar untuned for over a year now (I think its a stupid idea but have had alot of tuning issues, theres not one good shop in all of wisconsin for tuning my car)
Its not a good idea but ive been fine and I tend to beat the crap out of my car every now and then
Its not a good idea but ive been fine and I tend to beat the crap out of my car every now and then
10-25-2009, 10:48 PM
#9
I ran 6psi untuned with a T3/T04B and my open loop AFRs were between 10 and 12:1. But I also had 440cc injectors. Zero misfire count on stock timing and stock EGTs. It ran pretty well but the tune was less than ideal. LTFT was ~ -20%, OL AFR started at 10:1, got leaner as boost increased and occasionally the engine would hesitate for a second when floored. It was an experiment and far from a failure, IMHO.
When my 304 log mani cracked (turbo weight, not EGT) I decided that it was much easier to get an FIC than try to tune the ECU with different MAF tubes, potentiometers, etc. IMO it's possible to run low boost on the stock ECU but tuning it would be a PITA and still have flaws that could only be fixed with add-on electronics (MAF calibrator, clamp, AFR calibrator, piggyback, etc.). After considering all the options, the FIC best fit my needs and budget.
If you have to run FI without EM, I'd recommend that you at least get bigger injectors. I wouldn't go bigger than 440cc either or the ECU will probably have a fit with the fuel trims.
BTW, just a little FYI but if you have the right OBDII scantool and don't mind reading Lambda, you can monitor and log your AFRs from the Toyo WB O2. I'm using an ELM327 and netbook with PCMScan to monitor/log AFR, EGT and everything else anyone could possibly want to monitor. I also have a AEM UEGO since the Netbook would be nearly impossible to monitor while driving.
When my 304 log mani cracked (turbo weight, not EGT) I decided that it was much easier to get an FIC than try to tune the ECU with different MAF tubes, potentiometers, etc. IMO it's possible to run low boost on the stock ECU but tuning it would be a PITA and still have flaws that could only be fixed with add-on electronics (MAF calibrator, clamp, AFR calibrator, piggyback, etc.). After considering all the options, the FIC best fit my needs and budget.
If you have to run FI without EM, I'd recommend that you at least get bigger injectors. I wouldn't go bigger than 440cc either or the ECU will probably have a fit with the fuel trims.
BTW, just a little FYI but if you have the right OBDII scantool and don't mind reading Lambda, you can monitor and log your AFRs from the Toyo WB O2. I'm using an ELM327 and netbook with PCMScan to monitor/log AFR, EGT and everything else anyone could possibly want to monitor. I also have a AEM UEGO since the Netbook would be nearly impossible to monitor while driving.
10-25-2009, 11:37 PM
#12
Senior Member
Music City Scions
Scikotics
SL Member
Join Date: Jun 2005
Location: TN
Posts: 16,747
This is the problem with saying "yes you can run 6lbs on the stock computer". The test to determine it was fine was based on a 16G, with specific Pipe sizing. Then people take it and run with it thinking it works across the board. Answer YES if you run a 16G. NO if you run something larger. You change things when you increase the CFM's, pipe routing, adding an intercooler, and running injectors. I have had people ask me, and then tell me that they basically have a full kit but no management. DUMB idea basically. I tell them 6lbs on a 16G fine, but don't think it applies to every turbo.
10-26-2009, 12:20 AM
#14
There's more to it than just turbo size but in general, of course a small turbo is better suited to stock ECU use. IMO a T3-60 trim would work pretty well with the stock ECU at modest boost and HP levels.
I've heard this small vs big turbo at same psi argument a lot on SL. Can someone please explain why a bigger turbo is pushing more air volume into the engine at 6psi (measured post TB) than a small turbo? I suppose the small turbo might heat the air more but is it really enough to make a big difference in the volume? My understanding is that the small turbo simply can't move enough air to maintain the same psi at higher volumes, not that it somehow pressurizes a smaller air volume to the same pressure. The post-TB psi is just a measure of the air pressure within the fixed volume area of the intake manifold. If the air temp is the same at a given psi, the volume will be the same.
I've heard this small vs big turbo at same psi argument a lot on SL. Can someone please explain why a bigger turbo is pushing more air volume into the engine at 6psi (measured post TB) than a small turbo? I suppose the small turbo might heat the air more but is it really enough to make a big difference in the volume? My understanding is that the small turbo simply can't move enough air to maintain the same psi at higher volumes, not that it somehow pressurizes a smaller air volume to the same pressure. The post-TB psi is just a measure of the air pressure within the fixed volume area of the intake manifold. If the air temp is the same at a given psi, the volume will be the same.
10-26-2009, 12:41 AM
#16
Ok regardless of you doing it succesfully " dont run your car untuned!".
Noobs please pay attention to what I just said. I am glad it worked for you cburg but I have to throw my opinion out there cause I dotn wanna see noobs doign this and blowing up tC's everywhere!
And lets keep it on topic please!
Noobs please pay attention to what I just said. I am glad it worked for you cburg but I have to throw my opinion out there cause I dotn wanna see noobs doign this and blowing up tC's everywhere!
And lets keep it on topic please!
10-26-2009, 01:25 AM
#18
Think of it this way, at 70F what is the volume of air in a tire at 32psi? Before you say that it depends on the size of the tire, the tire in this case is exactly the same size (the post-turbo intake tract).
Anyway, I hope the SAFC works for you but I'm afraid your T04E may exceed the limits of a simple MAF signal modifier. I hope you have a good wastegate setup to bypass a lot of exhaust gasses to avoid boost creep. IIRC the MAF outputs about 4.25V max on a NA engine and the MAF upper limit is 5V so you have only so much room to add voltage (measured air volume). Adding larger injectors would go a long way and there are all kinds of other tricks like lowering measured coolant and IAT but modding those things is tricky and often accompanied by unwanted side-effects such as timing advance.
FWIW, the Deatschwerks 440cc are PnP and the resistance is within 5% of stock. I'm still running them without the turbo and mpg is the same, driveability is the same, basically I can't tell they're there without checking LTFT. One negative is that it takes the ECU some time to fully adjust to larger injectors. At first you'll see bouncing AFRs and some minor driveability issues but after a few hundred miles, same as stock.
10-26-2009, 03:54 PM
#19
Senior Member
Music City Scions
Scikotics
SL Member
Join Date: Jun 2005
Location: TN
Posts: 16,747
That's simply not true. A larger turbo can pressurize a larger volume of air than a small turbo but at the same pressure, the air volume is the same if the air temp is the same.
Think of it this way, at 70F what is the volume of air in a tire at 32psi? Before you say that it depends on the size of the tire, the tire in this case is exactly the same size (the post-turbo intake tract).
Anyway, I hope the SAFC works for you but I'm afraid your T04E may exceed the limits of a simple MAF signal modifier. I hope you have a good wastegate setup to bypass a lot of exhaust gasses to avoid boost creep. IIRC the MAF outputs about 4.25V max on a NA engine and the MAF upper limit is 5V so you have only so much room to add voltage (measured air volume). Adding larger injectors would go a long way and there are all kinds of other tricks like lowering measured coolant and IAT but modding those things is tricky and often accompanied by unwanted side-effects such as timing advance.
FWIW, the Deatschwerks 440cc are PnP and the resistance is within 5% of stock. I'm still running them without the turbo and mpg is the same, driveability is the same, basically I can't tell they're there without checking LTFT. One negative is that it takes the ECU some time to fully adjust to larger injectors. At first you'll see bouncing AFRs and some minor driveability issues but after a few hundred miles, same as stock.
Think of it this way, at 70F what is the volume of air in a tire at 32psi? Before you say that it depends on the size of the tire, the tire in this case is exactly the same size (the post-turbo intake tract).
Anyway, I hope the SAFC works for you but I'm afraid your T04E may exceed the limits of a simple MAF signal modifier. I hope you have a good wastegate setup to bypass a lot of exhaust gasses to avoid boost creep. IIRC the MAF outputs about 4.25V max on a NA engine and the MAF upper limit is 5V so you have only so much room to add voltage (measured air volume). Adding larger injectors would go a long way and there are all kinds of other tricks like lowering measured coolant and IAT but modding those things is tricky and often accompanied by unwanted side-effects such as timing advance.
FWIW, the Deatschwerks 440cc are PnP and the resistance is within 5% of stock. I'm still running them without the turbo and mpg is the same, driveability is the same, basically I can't tell they're there without checking LTFT. One negative is that it takes the ECU some time to fully adjust to larger injectors. At first you'll see bouncing AFRs and some minor driveability issues but after a few hundred miles, same as stock.
Sorry....CFM at a Given PSI on a Big turbo does not equal the same amount of CFM's at the same PSI on a small turbo. This is why you can not simply throw ANY turbo onto a stock ECU and think it will be alright as long as you stay at 6lbs of boost or less.
That's the point, the Air Temp will NOT be the same. Smaller turbos generate more heat for starters. And I've mentioned that it was more than just turbo size. People have added intercoolers (which obviously changes the piping), also some even put on injectors and think the Stock ECU can adjust for it. Adding an intercooler changes temps obviously as well.
Tire PSI has nothing to do with Turbo PSI...not a good comparison there. Again, you will not be pushing the same Temps.
