Interesting Outcome from Data Logging....

[edmundu]

So, I have a custom PDX Tuned STI LGT. (I have the STI swap, plus UP/DP.)

Recently I received a revised map(New afr targets), and wanted to test it out. I have a wideband O2, along with Ecuexplorer to log the essentials. I also had vehicle speed selected. I started looking at the before/after number's, and noted that the acceleration times improved ALOT!

Here are the number's:
(all times in seconds)
OLD Map:
40-100mph = 8.8
40-110mph = 11.1
40-120mph = 13.7

NEW Map:
40-100mph = 8.3
40-110mph = 10.4
40-120mph = 13.3

Note: I use 40mph as a starting point, so I don't have to do an abusive launch, and it also allows you to start from 2nd gear at about 30mph, so by the time you hit 40mph, it's no different from a standing start! These runs were done in the exact same location for consistency, on level ground, on a private road.

Conditions
Air temp = 38
Atmospheric psi = 14.55
And were run about 8 minutes apart.

To give these times some meaning, I looked up some number's for a stock LGT, STI and a Porsche 911S.

Stock LGT
40-100mph = 12.5
(There weren't any higher speeds that I could find.)
Stock STI
40-100mph = 10.1

Porsche 911S 2005 (997 chassis)
40-100mph = 8.2
40-110mph = 10.2
40-120mph = 12.4

Yeah baby, within 3-4 car lengths of a 350bhp 911! (Porsche is known for conservatively underating their power figures). It flatout wasted the stock LGT, and hammered on a stock STI, even compared to the old map, it stomped it pretty thoroughly as well. There is still some power being left on the table with this setup, I'm guessing about 10-15whp.

Nonbeliever's: I realize that my times cannot be directly compared, due to variables such as temp, elevation, etc. But the times I quoted were from C&D, and they use correction factors to standardize their number's. Mine were from a cool winter day, but the baro pressure wasn't that high. So in reality they are not far off if at all.

Last fall, on the old map I ran a 13.08@104.5mph, with a 1.85 60' time. Now it is looking like I should be able to shave that time by a good 0.5 second, and likely pickup 4-5mph. Putting this setup solidly in the 12's. I can't wait for the tracks to open to verify. Because come April, I'll have a new setup that should easily drop another 1/2 second....

Update:

Conditions
Air temp = 58
Atmospheric psi = 14.7

I ran another test yesterday, same location and all, just warmer weather. The times:

40-100mph = 8.41
40-110mph = 10.53
40-120mph = N/A (Had to end it earlier)

Didn't lose much as I had expected! These conditions, are very, very close to standard conditions. The elevation for this area is 360ft. which pretty much wipes out the lower temp advantage in my book.

As a comparison:

Density Altitude for the runs:

Run 1: -189ft. asl
Run 2: +622ft. asl

[jmanzs]

:munch:

[PhilT]

All testing done on a closed track of course ;)

Nice to actually document improvements instead of having to rely on your butt dyno, and some good times to boot !

Can you post any engine info from the logs or were you asked to keep it private ?

[edmundu]

Sorry, should have posted it! Here they are:

[sutter2k]

So how much more power would be needed to run past that 911?

Though at 38 degress, the 911 may also have slighly better numbers as well.

[edmundu]

So how much more power would be needed to run past that 911?

Though at 38 degress, the 911 may also have slighly better numbers as well.

To make up the 3-5 car lengths would likely take another 20-25whp. Even though the air temp was 38, if you couple it with DA(density altitude), it really isn't that big of an advantage (-387 ft vs 0 ft/sealevel). The barometer was in the lower 29's, we've had it in the mid 30's which would have been a pretty good advantage.

Just to clarify the 20-25 additional Hp would need to come in the powerband of 5K-7K, so it would require a turbo change from the vf39 I have now. Perhaps alky injection might get it there, as would c16, but that would be pushing it...

[PhilT]

Very nice, your fuel injector cycle seems pretty maxed out up top too. One reading of just over 100%, how can it do that ?

[warteaufmich]

100% indicated = 80% actual, I think.

[edmundu]

Very nice, your fuel injector cycle seems pretty maxed out up top too. One reading of just over 100%, how can it do that ?

Inj duty cycle, is what the ecu is trying to hit for a afr target. So let's say you plugged in 10:1 for an afr, the inj duty cycle would have climbed even higher. In fact, that was what the old map was doing. It was a richer afr, and was actually hitting 115% or more!

The duty cycle, has to do with the opening time of the intake valve, so if it is ineffect spraying over 100%, then fuel is being injected even with the valve closed. Or at least that is how I understand it.

And yes, I am at the safe limits of the stock injector. The afr is still very conservative, so there is some room left to lean it out further, giving a little more power, and still keeping the cuty cycle under or right at 100%.

[sutter2k]

To make up the 3-5 car lengths would likely take another 20-25whp. Even though the air temp was 38, if you couple it with DA(density altitude), it really isn't that big of an advantage (-387 ft vs 0 ft/sealevel). The barometer was in the lower 29's, we've had it in the mid 30's which would have been a pretty good advantage.

Just to clarify the 20-25 additional Hp would need to come in the powerband of 5K-7K, so it would require a turbo change from the vf39 I have now. Perhaps alky injection might get it there, as would c16, but that would be pushing it...
catback may yield a few hp in the 5k-7k range + alcohol injection would seem to do it.
though vf series turbo chargers seem to fall flat after 5k on a 2.5 liter(though stock fuel is is close to done as well). Couple that with another car that makes most of its hp in that range, we are susceptable to being reeled in.

[Ridgeracer]

How does the STI swap compare to a TDC tuned Momentum 40T w/ FMIC plus tune?

[sumfoo1]

wow that duty cycle is measured funny then


i've always been under the impression that the injectors are pegged at 100%

[edmundu]

wow that duty cycle is measured funny then


i've always been under the impression that the injectors are pegged at 100%

Well, not really. If you think of it as only having a set amount of time in which to deliver the fuel. Then a given injector flowing xxx cc/min will be able to deliver that amount in the set time.

All 4 stroke engines have the same amount of time to get the fuel into the combustion chamber.(let's not argue intake cam timing), I'm speaking strictly of the 4 stroke combustion cycle. So an injector that is larger can deliver the target amount fuel within the alotted amount of time. So running the injector at or above 100% duty, is really saying that the injector cannot deliver enough fuel in the given time, but there is still a fair amount of off-time while the engine goes through the other strokes of the cycle.

Newer injectors do not seem to be as sensitive to running higher duty cycles, as I suppose they do not get as hot, or are able to tolerate heat better. Regardless, the smart/safe thing to do is upgrade the injectors to keep them under 90%, or even better 85%. But don't go too big, as the bigger injector's spray pattern breaks down the lower the duty cycle, and this will impact your hot idle characteristics. Like anything else, figure out your power goals, and then go get the smallest injector that can handle the targetted hp.

[legacy_y_tu]

Well, not really. If you think of it as only having a set amount of time in which to deliver the fuel. Then a given injector flowing xxx cc/min will be able to deliver that amount in the set time.

All 4 stroke engines have the same amount of time to get the fuel into the combustion chamber.(let's not argue intake cam timing), I'm speaking strictly of the 4 stroke combustion cycle. So an injector that is larger can deliver the target amount fuel within the alotted amount of time. So running the injector at or above 100% duty, is really saying that the injector cannot deliver enough fuel in the given time, but there is still a fair amount of off-time while the engine goes through the other strokes of the cycle.

Newer injectors do not seem to be as sensitive to running higher duty cycles, as I suppose they do not get as hot, or are able to tolerate heat better. Regardless, the smart/safe thing to do is upgrade the injectors to keep them under 90%, or even better 85%. But don't go too big, as the bigger injector's spray pattern breaks down the lower the duty cycle, and this will impact your hot idle characteristics. Like anything else, figure out your power goals, and then go get the smallest injector that can handle the targetted hp.

Wow, great explanation of IDC's and injectors.

Thanks

[sutter2k]

How does the STI swap compare to a TDC tuned Momentum 40T w/ FMIC plus tune?

similiar. 40T seems to have a stronger spring and holds out a bit longer at redline.

40T's and vf series are still kind of small for a fmic on a 2.5
Define your goal. 40T is cheap. However, if your solution is merely a stop gap, go cheaper and get a used vf39/34 w/fmic. Also, various 18-20g's, pe1820s, etc, can sometimes be found used on nasioc for ~750-800. If all things are new, I'd shoot a tad bigger and get at least fp18g w/td06 housing for about 1k(still doesn't require doing a pump, just injectors).

[sandwood]

bump - edmundu, when you did this, did you roll onto full throttle from 30 mph so that you were at WOT by the time you hit 40 in 2nd? I might see if I can find a place to try and replicate this test.

[edmundu]

bump - edmundu, when you did this, did you roll onto full throttle from 30 mph so that you were at WOT by the time you hit 40 in 2nd? I might see if I can find a place to try and replicate this test.

Yep! I actually start logging around 29mph, and then stomp on it, so that by 40mph, I have been WOT for at least .5 second. This gives the turbo a chance to be spooled by 40mph. I log throttle obviously, to make sure that I was 100% for the min stated time.

Just be sure to select the same parameter's I did. It will allow you to see what weather conditions you had, it makes for a fairer comparison, except for elevation. I am pretty close to sea level, no higher than 300ft, I'd gather...