Tuning - Log Analysis Help

[GSXDNA]

I just bought a completely bone stock '99 GSX. I hooked up my laptop and logged some data using my EvoScan software program from my old Evo VIII. Anyways, there are a few things in this log file that I have questions about, so any insight on this would be much appreciated. First off, here is the log from a 2nd gear pull (I know, tuning is supposed to be done in 4th - haven't had the opporunity to open it up that much yet):

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So, I have two main concerns from this log:

1. Look how much my boost drops off at higher RPMs. Is this normal on a stock 2g? Could this be a result of the weak 2g OEM BOV?

2. My injector duty cycle looks like it's nearing 80%, which I understand to be the max any injectors should be asked to operate at. How are people safely running 15-16psi on stock injectors without reaching 100% IDC? What is the stock static fuel pressure of a 2g?

Thanks in advance for any insight.

 

[2gGSX]

1. Is that logged boost from a MAP sensor?

2. Without mass airflow logged, it's hard to tell what exactly is going on. Based on your timing, it looks like you are at the 1.4-1.6 g/rev range by redline. Based on that, your airflow should be around 21.5 lbs/min to 24.7 lbs/min. Given that the stock fuel map is set to 9.6 or 9.7:1 depending on your airflow, you should be flowing around 23.1/9.65 = 2.39 lbs/min of fuel. Your IDC at this point is about 76%, so you are flowing 450x4x.76/454 = 3.01 lbs/min of fuel, which is nowhere near where you should be.

The ECU is making you run more rich than you are supposed to be, indicating that you most likely have a boost leak somewhere after the turbo. Your ECU is seeing more airflow than actually is getting to the engine, which is why it is dumping fuel.

Instructions on how to do so are here: 2G Turbo DSM Boost Leaks -How to test and fix

The general consensus among the DSM crowd seems to be to run higher IDCs--most people are alright with 85% IDC usually, but that is up to your personal preference.

The stock "static fuel pressure" (referred to around here as the base fuel pressure) for a 2g is 43 psi.

Most people seem to do fine with third gear pulls up until they get larger turbos, so a fourth gear pull is not necessary.

Welcome to the forums, btw.

 

[GSXDNA]

1. Is that logged boost from a MAP sensor?

No, it was actually calculated based on load (100%=0psi, 200%=14.5psi). I know this isn't the best way to log boost, but I have found it to be fairly accurate in the past. Plus, it's the best I have to work with right now.

2. " ...it looks like you are at the 1.4-1.6 g/rev range by redline..."

Can you please further elaborate on what this is, and how you used it to calculate flow?

you most likely have a boost leak somewhere after the turbo.

That's what I suspected. Many thanks, you've been a great help!

 

[kenamond]

Load (g/rev) can be directly converted from the logged mass airflow (lb/min) and rpm. I'm not sure if 2gGSX just looked on the stock timing map to find out the load (from your 7k timing advance) or knew how you were computing boost and backcalculated g/rev.

The T25 turbo and stock exhaust peter out at higher rpm; the small A/R turbine housing and small/restrictive exhaust just don't flow well up there. That's why the boost is dropping.

Any idea how the knock values are being read by your logger? I was under the impression that the 2g ECU didn't provide knock count to the OBDII port. Perhaps the stock timing map is known by the logger and it's back-calculating knock count from timing advance, RPM, load, coolant temp and IAT.

Stock boost is 10-12psi, so I'm not sure how accurate the boost calculations in your log are.

 

[2gGSX]

It seems that the newer loggers with MUT-II data reading capabilities have the ability to read knock sensor voltage. That's the way it is with ECU+, anyways.

I had calculated the load based on his timing curve, and comparing it to the stock 2g timing map. I was under the assumption that no timing was being pulled out for either coolant temps (they're below 206) or intake temps (not logged, so just a guess).

The g/rev is as Mack described. It represents the "third axis" in your stock ECU's 3D timing and fuel maps (Load v. RPM v. Timing Advance, and Load v. RPM v. Target AFR respectively). It looks like this:

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Basically the ECU just reads your RPM and load, and then decides what AFR and timing advance to run.

 

[GSXDNA]

Awesome, thanks guys. I'm actually quite familiar with Load, but I've just never known the units (g/rev) for it. That all makes sense.

So, lets say I do have a boost leak (which is quite possible after just taking a quick glance at my frayed lower IC pipe). After the leak is fixed, how much should I expect to see the boost drop off top end? Surely boost shouldn't be going from 9psi to 3 or 4?

Also, with larger diameter IC and exhaust piping, how much of a decrease in drop off should I expect with the stock turbo?

And yes, I was actually quite surprised to see that knock was successfully logged as well. I was just trying it as a long shot, and it worked!

Thanks.

 

[2gGSX]

I'm not familiar with how to use EvoScan's boost readout or how it's calculated, so I can't really comment on it. The 100% load = 0 psi, and 200% load = 15 psi doesn't seem like it would work very well IMO, since it varies between turbos.

Based on my own logs, it looks like my boost curve (from a MAP sensor) peaks a little before peak load. You could use the load curve to estimate spool, but I don't think you could use it to measure boost. Not very accurately, at least.

The stock turbo can't hold 15 psi to redline to begin with since it's so little. The upgraded exhaust and upper intercooler piping "L" pipe would probably reduce spool via getting rid of restrictions.

 

[kenamond]

Awesome, thanks guys. I'm actually quite familiar with Load, but I've just never known the units (g/rev) for it. That all makes sense.

So, lets say I do have a boost leak (which is quite possible after just taking a quick glance at my frayed lower IC pipe). After the leak is fixed, how much should I expect to see the boost drop off top end? Surely boost shouldn't be going from 9psi to 3 or 4?

Also, with larger diameter IC and exhaust piping, how much of a decrease in drop off should I expect with the stock turbo?

And yes, I was actually quite surprised to see that knock was successfully logged as well. I was just trying it as a long shot, and it worked!

Thanks.

The boost leaks aren't going to do much for your boost values. The engine is just getting less air than it's expecting and therefore adding too much fuel. So your AFR is hosed. I guess if it's bad enough, it may bog the engine down and boost along with it. Don't get me wrong, though....boost leaks are BAD. Pig rich = slow.

If boost is being computed from airflow and rpm, you could still have 15psi boost in the manifold but with low airflow numbers, and the logger would compute a lower-than-actual boost value. Pressure and airflow are completely different animals.

The biggest restriction in the intake IMO is the upper intercooler pipe where it goes between the body and air filter box (take the filter box off and take a look...UUUUUGLY). Maybe the next biggest is the air filter box itself. Those will help with airflow and therefore load and therefore torque&hp. I'm not sure how much it'll affect top-end airflow though. And then you get to deal with increased IATs unless you fab/buy a cold air intake to keep from breathing in hot engine bay air (20° hotter IATs with a K&N FIPK but w/o the cold air intake).

The larger (catless if possible/legal) exhaust will do the most in terms of top end airflow (again IMO). That's the situation I'm in right now (or suspect I'm in). I have all of the intake mods and an upgraded turbo, but my airflow numbers are still very low. I suspect it's due to the fact that my exhaust is still stock. I've recently freed up some cash to get the 3" Megan turboback exhaust, so I get to find out if I'm full of it or not. I'd bet that's why they recommend the exhaust before the turbo in the staged upgrade paths of every sight I've seen. Too bad my T25 blew before my stock exhaust fell off. Que sera.

 

[GSXDNA]

I'm not familiar with how to use EvoScan's boost readout or how it's calculated, so I can't really comment on it. The 100% load = 0 psi, and 200% load = 15 psi doesn't seem like it would work very well IMO, since it varies between turbos.

Based on my own logs, it looks like my boost curve (from a MAP sensor) peaks a little before peak load. You could use the load curve to estimate spool, but I don't think you could use it to measure boost. Not very accurately, at least.

The stock turbo can't hold 15 psi to redline to begin with since it's so little. The upgraded exhaust and upper intercooler piping "L" pipe would probably reduce spool via getting rid of restrictions.

Yeah, I didn't think Load was the best way of calculating boost. That's actually not a preset value in EvoScan, it's just a value I calculated based on Load. I just ordered a boost gauge, so that should at least let me know where I'm at currently.

Is the stock turbo on the 1G the same as the stock turbo on a 2G? I've heard that (on a 1G) by simply upgrading all the plumbing (IC piping, exhaust, intake, 02 housing) and raising the boost a few pounds there is another 70-80 hp to be had. How true is this?

 

[2gGSX]

The 1g had the TD05H-14b for the most part (autos had a TD04-13g, which is much more anemic). The reason why those mods make such a bigger difference on the 1g is because the turbo is bigger, and capable of more airflow. The T25 (stock 2g turbo) on the other hand, is fairly close to being maxed out from the factory.

Mack's advice of upgrading the intake/intercoolerpipes/exhaust system before a turbo upgrade is the recommended pathway still. You may not see as big a gain from this as a 1g would, or perhaps even if you were to do a turbo upgrade first, but without these mods you wouldn't get as much out of a turbo upgrade anyways.

In short, the tuning guide is a pretty proven upgrade path.

 

[GSXDNA]

The 1g had the TD05H-14b for the most part (autos had a TD04-13g, which is much more anemic). The reason why those mods make such a bigger difference on the 1g is because the turbo is bigger, and capable of more airflow. The T25 (stock 2g turbo) on the other hand, is fairly close to being maxed out from the factory.

Mack's advice of upgrading the intake/intercoolerpipes/exhaust system before a turbo upgrade is the recommended pathway still. You may not see as big a gain from this as a 1g would, or perhaps even if you were to do a turbo upgrade first, but without these mods you wouldn't get as much out of a turbo upgrade anyways.

In short, the tuning guide is a pretty proven upgrade path.

Great, thanks. I planned on doing the exhaust, IC piping, 02 housing, and ported manifold first anyways...just curious as to how much of a hp increase i would see. If I upraded all that piping, port the manifold and 02 housing, and raise the boost 2-3psi I'm anticipating about a 50-60hp increase. I guess time will soon tell.

 

[2gGSX]

Estimated HP increases are always an "iffy" subject at best. You should definitely feel it in the butt dyno though.

 

[kenamond]

Great, thanks. I planned on doing the exhaust, IC piping, 02 housing, and ported manifold first anyways...just curious as to how much of a hp increase i would see. If I upraded all that piping, port the manifold and 02 housing, and raise the boost 2-3psi I'm anticipating about a 50-60hp increase. I guess time will soon tell.

If you port the manifold, you'll also need to port the T25 turbine housing (if you're opening it up to a 7cm^2 gasket match). Don't port out the dividers in the mani collector, though. They separate 1+4 and 2+3 flow from each other and keep 1 and 4 or 2 and 3 from blowing up each others' runners. If you can have the DP in hand when you port the O2 housing, you can probably match them up nicely.

I ported my T25 housing as a practice run before doing my FP B28.

Don't forget to upgrade the BOV, though you'll probably have no choice if you get an aftermarket UICP (they usually don't flange the UICP for the stock 2g BOV).

I'd do a boost leak test before you rip the intake off to upgrade. Then you can find out how your BISS, injector insulators, PCV valve, etc. are doing. If they're leaking, you can order that stuff and do the whole lot at once.

 

[GSXDNA]

If you port the manifold, you'll also need to port the T25 turbine housing (if you're opening it up to a 7cm^2 gasket match). Don't port out the dividers in the mani collector, though. They separate 1+4 and 2+3 flow from each other and keep 1 and 4 or 2 and 3 from blowing up each others' runners. If you can have the DP in hand when you port the O2 housing, you can probably match them up nicely.

I ported my T25 housing as a practice run before doing my FP B28.

Don't forget to upgrade the BOV, though you'll probably have no choice if you get an aftermarket UICP (they usually don't flange the UICP for the stock 2g BOV).

I'd do a boost leak test before you rip the intake off to upgrade. Then you can find out how your BISS, injector insulators, PCV valve, etc. are doing. If they're leaking, you can order that stuff and do the whole lot at once.

I'm actually heading to the parts store after work today to pick up some items to make a boost leak tester. After I confirm there are no leaks or repair any leaks, I'm getting the Buschur UICP w/ 1G BOV unit.

I was planning on just purchasing the ported 02 housing and manifold because this is my only car and I won't be able to have it out of commision for more than a few hours at a time. How difficult/time consuming is it to "port" a manifold or an 02 housing? What does it involve?

 

[kenamond]

I'm actually heading to the parts store after work today to pick up some items to make a boost leak tester. After I confirm there are no leaks or repair any leaks, I'm getting the Buschur UICP w/ 1G BOV unit.

I was planning on just purchasing the ported 02 housing and manifold because this is my only car and I won't be able to have it out of commision for more than a few hours at a time. How difficult/time consuming is it to "port" a manifold or an 02 housing? What does it involve?

The problem with running a ported exhaust manifold/O2 housing is that you may have a very sudden change in diameter between parts (between mani/turbo/O2/DP) and this can actually hurt performance by significantly disrupting exhaust flow.

Porting is kind of an art, but if you're handy and careful, it's not really too hard. It will take you some time, though. If you have an air compressor, you can buy a die grinder for $20. If you don't have an air compressor, Harbor Freight sells electric die grinders for about $50. That's what I used. Then you need burrs (bits) which are about $20/ea. If you're just porting the turbine housing to match the exhaust manifold (if the porting just opens up the collector diameter), then you could probably port the turbine housing in about 45 minutes if you don't dilly-dally, but I'd earmark more like 2 hours additional. And this assumes you already have the turbine housing off the car. I'm not sure if you can disconnect the T25 housing from the center section without dropping the turbo. I dropped my T25 (it blew) and took my time porting the mani, O2, and turbine housing.

If you're already planning on dropping the turbo, then it'll only add a couple of hours. Do a search for porting threads that I've posted to. I'm too lazy at the moment to search, but I've posted some detailed threads about what pieces/parts you need, what you have to do, etc. Then you can decide if this is something you want to attempt.

I think that you'll require several hours anyway to change out all of the exhaust parts, and you might want to do this on a weekend and bum a ride here and there if needed. You may run into snags tha require you to order parts anyway (like if you break bolts or strip something).

EDIT: Here are some links to porting posts I've made in the past:

http://www.dsmtuners.com/forums/newbie-forum/224791-porting-exhausted-mani.html?highlight=carbide
http://www.dsmtuners.com/forums/newbie-forum/227178-6cm-turbo-7cm-manifold.html
http://www.dsmtuners.com/forums/newbie-forum/234345-good-porting-bit.html#post50434034

The last link actually has a few links in it, probably to the first two and others.

 

[GSXDNA]

The problem with running a ported exhaust manifold/O2 housing is that you may have a very sudden change in diameter between parts (between mani/turbo/O2/DP) and this can actually hurt performance by significantly disrupting exhaust flow.

Porting is kind of an art, but if you're handy and careful, it's not really too hard. It will take you some time, though. If you have an air compressor, you can buy a die grinder for $20. If you don't have an air compressor, Harbor Freight sells electric die grinders for about $50. That's what I used. Then you need burrs (bits) which are about $20/ea. If you're just porting the turbine housing to match the exhaust manifold (if the porting just opens up the collector diameter), then you could probably port the turbine housing in about 45 minutes if you don't dilly-dally, but I'd earmark more like 2 hours additional. And this assumes you already have the turbine housing off the car. I'm not sure if you can disconnect the T25 housing from the center section without dropping the turbo. I dropped my T25 (it blew) and took my time porting the mani, O2, and turbine housing.

If you're already planning on dropping the turbo, then it'll only add a couple of hours. Do a search for porting threads that I've posted to. I'm too lazy at the moment to search, but I've posted some detailed threads about what pieces/parts you need, what you have to do, etc. Then you can decide if this is something you want to attempt.

I think that you'll require several hours anyway to change out all of the exhaust parts, and you might want to do this on a weekend and bum a ride here and there if needed. You may run into snags tha require you to order parts anyway (like if you break bolts or strip something).

EDIT: Here are some links to porting posts I've made in the past:

http://www.dsmtuners.com/forums/newbie-forum/224791-porting-exhausted-mani.html?highlight=carbide
http://www.dsmtuners.com/forums/newbie-forum/227178-6cm-turbo-7cm-manifold.html
http://www.dsmtuners.com/forums/newbie-forum/234345-good-porting-bit.html#post50434034

The last link actually has a few links in it, probably to the first two and others.

Thanks for all the info. That all sounds fairly time consuming and precise. Maybe I'll buy a ported O2 housing and manifold, and attempt to port my turbine housing myself.