EVOIII Airflow?

[daren_p]

Just wondering what kind of airflow other people were seeing with the evoIII, Im thinking my airflow is abit low. With inlet temps in the 80's I see ~30 - 31 lb/min @ 18 psi of boost according to my autometer gauge (which is accurate). I saw as much as 32 lb/min this spring when the turbo was first installed running about 15.5 psi (didn't have the fuel system installed yet) but the intake temps were in the 40's. Now how exactly is the airflow calculated?, Im guessing its done by the MAF? I know I have 2 small boost leaks (tb shaft seals & jpipe weld) will this have any effect? I have all the standard bolt on's but am only running the HRC side mount ic (would this be limiting my flow at all?).

 

[90AWDTalon]

I've logged as high as 46lb/min at 20psi, I have no idea what the inlet temps were, but it was pretty warm out.

 

[daren_p]

I've logged as high as 46lb/min at 20psi, I have no idea what the inlet temps were, but it was pretty warm out.

Holly sh*t, are you sure thats right, I've never heard of anyone logging that high on the evo? That should be around 460 hp or so. I think shapegsx has logged 42 lb/min or so but I think that was at ~27 psi?

 

[90AWDTalon]

Holly sh*t, are you sure thats right, I've never heard of anyone logging that high on the evo? That should be around 460 hp or so. I think shapegsx has logged 42 lb/min or so but I think that was at ~27 psi?

I know my horsepower isn't that high, but about 3 weeks ago I went to 1/8 drags and ran 7.60 seconds and was only logging about 42 lb/min. Looking at the 1/4 mile list that puts me between 11.5 and 11.8 in the quarter. And based on the weight of my car that puts at 400+ whp. But if you look at the dyno under my user name that was recent and during that run I logged 45 lb/min at 90% duty cycle on 780cc injectors with a base fp of 49psi with an afr of 10.0:1 by there air/fuel meter and 11.1:1 according to my plx m-300. Doesn't seem possible but everything except those dyno numbers points that that may be correct.

 

[98spydert]

Unless your MAFT is calibrated correctly, that number isn't accurate. If you're using your MAFT to tune, it's even more inaccurate.


I logged 39 lbs/min at 22psi a few months ago. Hoping for low 40s with the new cams.

 

[90AWDTalon]

Unless your MAFT is calibrated correctly, that number isn't accurate. If you're using your MAFT to tune, it's even more inaccurate.


I logged 39 lbs/min at 22psi a few months ago. Hoping for low 40s with the new cams.

MAFT is zero'd out, I'm doing all the tunning with my eprom.

 

[98spydert]

MAFT is zero'd out, I'm doing all the tunning with my eprom.

That sure doesn't mean it's calibrated. I do all tuning through DSMLink, but in order to get my stupid POS MAFT to send an accurate signal to the ECU, I had to alter the signal 16%-24% by calibrating it with DSMLink and a GM 3bar MAP.

 

[90AWDTalon]

That sure doesn't mean it's calibrated. I do all tuning through DSMLink, but in order to get my stupid POS MAFT to send an accurate signal to the ECU, I had to alter the signal 16%-24% by calibrating it with DSMLink and a GM 3bar MAP.

Could you explain how to do this calibration? Also if I wasn't getting that high of airflow wouldn't I be super rich? I was sceptical myself until I ran those 1/8 mile times. What kind of airflow numbers are people getting when they run mid to upper 11's?

 

[98spydert]

It's basically just compairing externally logged data and the ECUs data all logged by DSMLink. For example, WB02 vs. estimated AFR or GM3bar vs. estimated boost. I'd explain the process but it would take me all night and I'm not sure it's ok to copy and paste from the DSMLink forums. Some private boards frown on that.

Also if I wasn't getting that high of airflow wouldn't I be super rich?

Couldn't tell ya. No two people get the same results with the MAFT. I tried to get to the bottom of the mysterious MAFT settings that a lot of people end up with and the answer I recieved from Bob at Full Throttle Speed was:

Blow thru can seriously shift the corrections depending on the pipe sizes and couplers used.

My MAFT was off 16-24% lean, not rich. Combined with fine tuning via the EPROM, who knows what your airflow really is.

 

[90AWDTalon]

I'm not that familiar with how dsmlink works, but with the eprom you can change code that relates to the maf sensor, that is way beyond my current abilities though. When you corrected your maft did you make the adjustments in dsmlink or the maft conroller?

I'm using blowthru with 2.5" pipping and the couplers that fullthrottle speed sells.

 

[98spydert]

Correction, that was a 21%-29% change I've made. I went back and looked.

I made the initial 25% change using the MAFT base settings because it changes the entire curve in 5% increments. After that I fine tuned the -4% to 4% changes with DSMLink airflow sliders.

 

[90AWDTalon]

It's basically just compairing externally logged data and the ECUs data all logged by DSMLink. For example, WB02 vs. estimated AFR

So what your saying if you were at a portion of the map that said you should have 9.5:1 afr, but you logged 11.1:1 with you WB02 you make the correction on the maft? If thats the case I can see how this could get realy complicated because if your air flow is off that far then you aren't in that portion of the map any more.

The car is running really good at its corrent tune, I'm wondering if its worth messing with just to get accurate logs. I'm still curious about how all this works if you don't mind talking about it.

So the dsmlink forums are private, I'm guessing theres no way to join with out having dsmlink?

 

[98spydert]

So what your saying if you were at a portion of the map that said you should have 9.5:1 afr, but you logged 11.1:1 with you WB02 you make the correction on the maft? If thats the case I can see how this could get realy complicated because if your air flow is off that far then you aren't in that portion of the map any more.

The car is running really good at its corrent tune, I'm wondering if its worth messing with just to get accurate logs. I'm still curious about how all this works if you don't mind talking about it.

So the dsmlink forums are private, I'm guessing theres no way to join with out having dsmlink?

That's the general idea. If it's running right and you're not having any tuning issues, I don't know if I'd bother. Just think, if you figure out your off by even 10% and make that change, now your fuel is off and the timing table is most likely different. You'd basically have to start from scratch and re tune the car.

And yes, the forums are a support forum for DSMLink owners so they don't allow non users to join unfortunately.

 

[spyderturbo007]

With inlet temps in the 80's I see ~30 - 31 lb/min @ 18 psi of boost according to my autometer gauge (which is accurate).

In getting your 30lbs/min did you remember to compensate for the correction factor provided you are running a SAFC?

I have all the standard bolt on's but am only running the HRC side mount ic (would this be limiting my flow at all?).

It's not going to limit flow, but you might have higher intake temps, just remember that what you see on the logger is the temperature of the initial air. It is calculated before the turbo/intercooler and all "that other jazz"

I am logging about 31 lbs/min with the EVO-III. I'm still on the stock exhaust so that's a restriction, but I don't mind.

 

[daren_p]

In getting your 30lbs/min did you remember to compensate for the correction factor provided you are running a SAFC?



It's not going to limit flow, but you might have higher intake temps, just remember that what you see on the logger is the temperature of the initial air. It is calculated before the turbo/intercooler and all "that other jazz"

I am logging about 31 lbs/min with the EVO-III. I'm still on the stock exhaust so that's a restriction, but I don't mind.

I don't have to worry about any correction factors, I'm using dsmlink. At what boost are you getting the 31 lb/min? Yes I do realise that the temp is the inlet temp. So your lb/min is calculated by the MAF? so boost leaks wouldn't effect this reading?

 

[CanadianTSi]

Shape logged 44lbs/min on one of his 11.7/11.8 runs...

 

[98spydert]

I don't have to worry about any correction factors, I'm using dsmlink. At what boost are you getting the 31 lb/min? Yes I do realise that the temp is the inlet temp. So your lb/min is calculated by the MAF? so boost leaks wouldn't effect this reading?

Boost leaks after the stock MAF or after the GM MAF will result in an airflow reading that's higher than is actually going in your engine. Then again, a big boost leak will result in lower airflow because the turbo drops out of efficiency and pumps hot air.

 

[spyderturbo007]

I don't have to worry about any correction factors, I'm using dsmlink. At what boost are you getting the 31 lb/min? Yes I do realise that the temp is the inlet temp. So your lb/min is calculated by the MAF? so boost leaks wouldn't effect this reading?

I wish I had and EPROM. Can I have yours?

17.5 psi gives me about 31 lb/min. Stock exhaust sucks. I also have the stock UICP (which goes when I get back from vacation).

A boost leak after the MAF will not be seen by the ECU. So although airflow into the engine is changing the ECU has no idea. So yes, a boost leak will not change the ECU's calculation of airflow. At WOT the ECU will have no way to compensate for added/lost airflow. During cruise/idle the ECU will try to compensate based on feedback from the O2 sensor.

 

[98spydert]

A boost leak after the MAF will not be seen by the ECU.

Read my post above, it will indirectly effect the airflow reading seen by the ECU.

 

[spyderturbo007]

Read my post above, it will indirectly effect the airflow reading seen by the ECU.

How?

The airflow is calculated by the ECU before the boost leak. It then calculates the appropriate amount of fuel to inject. If there is a boost leak in the system after the MAF how will the ECU see this? I can't see anyway that it would and would just result in a rich condition until the FT's compensate (assuming you are at cruise/idle and not WOT)

I am not being an ass, but I have always heard the opposite of what you are saying and would like some clairification.

 

[rightaway]

35-36 at 20 psi pump gas. thats with dsm link

 

[98spydert]

(assuming you are at cruise/idle and not WOT)

At cruise/idle, their will be a discrepancy between the air metered and the air entering the engine simply because there is a different amount of air passing through the meter than through the intake ports thanks to the leaks. But you're right, the ECU won't report this because it assumes no leaks after the metering device. The airflow value probably won't look any different either unless it's a good sized leak. Fuel trims will take care of it.

I was mainly referring to WOT since that's what this thread is about; max airflow. If there's a good sized leak, the turbo has to work harder to overcome the leak AND maintain the pressure you want at in the manifold. Any good sized leak is going to push your turbo out of it's efficiency range if you're already near the peak. If you drop out of the efficiency range, your airflow will drop dramatically.

Assuming a small leak that doesn't push the turbo out of it's efficiency range, airflow will be lost through the leak meaning less airflow entering the intake ports than passing through the metering device. This is probably a small amount, maybe 1 lb/min.

It doesn't matter if you're logging 40 lbs/min if it's not even getting into the engine, that was my point. Bottom line: Boost leaks suck! Fix them.

 

[spyderturbo007]

I agree with everything you posted above, execpt I still maintain that any boost leak will not be seen by the ECU.

Obviously there will be a difference between the air entering the combustion chambers and the air mass as read by the ECU. But the ECU will never know about the leak. It will just be injecting too much fuel into the combustion chamber.

Mayby we just misunderstood each other.

 

[damax03]

My highest is 42.8 lb/min at about 27psi, gonna try and run more boost and see how much it will make before it shoots the exhaust wheel out the tail pipe... On C16 of course...

 

[98spydert]

Obviously there will be a difference between the air entering the combustion chambers and the air mass as read by the ECU. But the ECU will never know about the leak. It will just be injecting too much fuel into the combustion chamber.

That's why I said it will indirectly see the leak The ECU obviously doesn't know about it but the number you see on your laptop will change with a boost leak due to the compensating the turbo will due to overcome the leak and maintain the psi you set your boost controller to.

I think we've got the same idea, just typing it out differently