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earlyapex
06-04-2005, 06:10 PM
Woke up bright and early today to get some dyno time on the gruppe-s mustang dyno.

Thanks to Mike for being the loud-peddle pusher / dyno operator while I fiddled with my SAFC and got high off my exhuast fumes.

My goal for today was to smooth out my power/torque curves with my 720's and just get a pretty solid tune with good AFR's.

We did over 10 pulls and the one I was happiest with was:

264.4whp / 261.4wtq

Mods:
Walboro 255 fuel pump
Vishnu sig 3"catback / Espelier 2.75" DP / RRE rally cat
SAFC
MBC at 1.4 bar (spikes to 1.6/1.7)
720's

Next is to polish off the tune on the street and maybe get cams next.

scans:

http://www.norcalmotorsports.org/users/bryan/mods/EVO/dyno/060405/finalPull.gif
http://www.norcalmotorsports.org/users/bryan/mods/EVO/dyno/060405/finalPull_AFR.gif

SouthernCrane
06-04-2005, 06:15 PM
Nice numbers B. 8) Does the car feel better to you on the street?

MarkSAE
06-04-2005, 07:40 PM
Nice #s Bryan. You gonna get a pair of 272s next??

earlyapex
06-04-2005, 08:29 PM
Nice numbers B. 8) Does the car feel better to you on the street?

Yea big time, smoothing out the curves made more usable hp and tq everywhere.

Up top feels very nice.

earlyapex
06-04-2005, 08:30 PM
Nice #s Bryan. You gonna get a pair of 272s next??

Thanks, yea when I go cams, it will most likely be the 272s.

earlyapex
06-04-2005, 10:13 PM
hrmmmm, finally looked at my pocketlogger logs from the dyno today.

My timing was kinda weird, AFR's looked fine on the dyno but my timing numbers seems really low for 720's. #"s where staying in the single digits until about 6500 then they go into the teens but only get to about 16 at 7000-7500.

I'm going to log the car on the road tomorrow and see if it's any different. If it isn't I think I might need to richen it up a bit again, even though the AFR's looked fine on the dyno, but look rich as hell on the pocketlogger logs. .96 and .98 :shock:

With my 720's, I should be seeing timing in the teens from 4000rpms up, and 19-24 in the upper revs.

There is more power to be found here. :D

http://www.norcalmotorsports.org/users/bryan/mods/EVO/dyno/060405/finalPull_LOG.gif

http://www.norcalmotorsports.org/users/bryan/mods/EVO/dyno/060405/pre_finallPull_LOG.gif

MarkSAE
06-04-2005, 11:00 PM
I'm going to log the car on the road tomorrow and see if it's any different. If it isn't I think I might need to richen it up a bit again, even though the AFR's looked fine on the dyno, but look rich as hell on the pocketlogger logs. .96 and .98 :shock:


This is why you should trust the wideband vs. the narrowband readings. I've seen huge variances in the narrowband readings w/ little change in the actual AFRs on the wideband on my 2g. Weather changes will affect the narrowband o2 voltage when actual AFRs haven't changed.

earlyapex
06-04-2005, 11:08 PM
Yup, agreed.

evo_dadi
06-05-2005, 05:48 AM
hot stuff :twisted: you should do the cams sooner also :wink: :twisted:

methods4
06-05-2005, 11:00 AM
What reflash are you running? :-P

Nice numbers though. 2-3 degrees of timing from 3200-3800. What happens when you richen that area up a little?

Widebandphillip
06-05-2005, 03:23 PM
the reason for the low timing in the peak torque area is because the factory runs the evos so lean. The 720's make it rich enough so you don't have to add any fuel at around 3500-4000.

earlyapex
06-05-2005, 04:50 PM
Did a couple road pulls today.

It's kinda pulling timing over the whole rev band, not bad pulls, but still pulling nonetheless. I richened up the whole rev band and some key areas and it felt better. I haven't datalogged it yet after that though.

For some reason, I forgot to set the sample rate on my logger before, so I was getting crappy 5 samples a sec, hence my like 7 data points before. Now it's at about 20/sec. much better.

Before I richened it up:

3rd gear:

http://www.norcalmotorsports.org/users/bryan/mods/EVO/dyno/060405/road_pull2_LOG.gif


4th gear:

http://www.norcalmotorsports.org/users/bryan/mods/EVO/dyno/060405/road_pull_LOG.gif

earlyapex
06-05-2005, 04:53 PM
the reason for the low timing in the peak torque area is because the factory runs the evos so lean. The 720's make it rich enough so you don't have to add any fuel at around 3500-4000.

In the mid range? hmm. all my hi settings are negative, maybe thats why my mid range has such crappy timing numbers. I'll richen it up a tad and see what kinda timing I get.

from around 4400 to 5600rpms on the dyno, I am running 11.4 AFRs.

markeddy
06-10-2005, 07:13 PM
Good topic.

Widebandphillip
06-12-2005, 07:44 PM
the reason for the low timing in the peak torque area is because the factory runs the evos so lean. The 720's make it rich enough so you don't have to add any fuel at around 3500-4000.

In the mid range? hmm. all my hi settings are negative, maybe thats why my mid range has such crappy timing numbers. I'll richen it up a tad and see what kinda timing I get.

from around 4400 to 5600rpms on the dyno, I am running 11.4 AFRs.

Peak torque area around 3500-3750. All the cars i've tuned with upgraded injectors either have little or no fuel taken out of that area due to how lean the factory runs the cars in that area.

earlyapex
06-12-2005, 07:49 PM
Peak torque area around 3500-3750. All the cars i've tuned with upgraded injectors either have little or no fuel taken out of that area due to how lean the factory runs the cars in that area.

Check my AFR graph, my AFR's are 11.5 and below 3500-4000.

I believe I am running -10/-12 or so right around there.

Absinthe
06-13-2005, 05:23 PM
generally don't we see peak feul at peak torque on a modded evo?

Widebandphillip
06-20-2005, 11:13 AM
Peak torque area around 3500-3750. All the cars i've tuned with upgraded injectors either have little or no fuel taken out of that area due to how lean the factory runs the cars in that area.

Check my AFR graph, my AFR's are 11.5 and below 3500-4000.

I believe I am running -10/-12 or so right around there.

You're talking about the dyno here. I'm talking about street. Street and dyno loads are completely different. This is why i always tune airfuel on the street. Notice how you occured problems when you logged on the street?


Absinthe, you basically only see that on standalone fuel maps. On the safc it's totally different because we're adding and subtracting from a "map" that's already there.

earlyapex
06-20-2005, 12:52 PM
Have you actually had a car with 720's tuned with no fuel taken out in the midrange?

My car sputters like a mofo if I do that. It *needs* fuel taken out.

Widebandphillip
06-20-2005, 04:35 PM
only at 3500 there is no fuel taken out. At 4000 there could be about -10 or so. This was a car on 680s.

earlyapex
06-20-2005, 04:54 PM
only at 3500 there is no fuel taken out. At 4000 there could be about -10 or so. This was a car on 680s.

wtf? Which means it has nothing to do with my car what-so-ever.

StockEVO
06-20-2005, 05:08 PM
Huh? :shock:

Was that in Engrish?


only at 3500 there is no fuel taken out. At 4000 there could be about -10 or so. This was a car on 680s.

airforce1
06-20-2005, 05:27 PM
not to be off topic but wasn't their mustang dyno recently incorrectly calibrated, thus perhaps showing lower than expected WHP? Rumor/fact?

earlyapex
06-20-2005, 05:37 PM
not to be off topic but wasn't their mustang dyno recently incorrectly calibrated, thus perhaps showing lower than expected WHP? Rumor/fact?

I have no idea

evo_dadi
06-20-2005, 05:41 PM
not to be off topic but wasn't their mustang dyno recently incorrectly calibrated, thus perhaps showing lower than expected WHP? Rumor/fact?

*grabs popcorn and watch*

GST
06-20-2005, 05:42 PM
not to be off topic but wasn't their mustang dyno recently incorrectly calibrated, thus perhaps showing lower than expected WHP? Rumor/fact?

Care to elaborate on that?

Mike

earlyapex
06-20-2005, 05:57 PM
perhaps showing lower than **expected** WHP?

Broken hearts after spending dough on Uber-Engineered-Eleventy-Billion power packages??

methods4
06-20-2005, 06:02 PM
*grabs popcorn and watch*

+1

Widebandphillip
06-22-2005, 11:50 AM
40 cc isn't that big of a difference. Besides it's a hell of a lot better than where you are right now.

earlyapex
06-22-2005, 11:54 AM
40 cc isn't that big of a difference. Besides it's a hell of a lot better than where you are right now.

What do you mean by that?

StockEVO
06-22-2005, 12:04 PM
Hi, I'm with stoopid!


40 cc isn't that big of a difference. Besides it's a hell of a lot better than where you are right now.

airforce1
06-24-2005, 03:32 AM
perhaps showing lower than **expected** WHP?

Broken hearts after spending dough on Uber-Engineered-Eleventy-Billion power packages??


:lol: :lol: :lol: No. Maybe ask them if they had their dyno calibrated themselves or by Mustang. I already know the answer. They were too cheap to spend the $$$. Their load is set too low, so the Evo looks like it is switching to a downhill map and AFR readings are misrepresented, hence people wondering where their WHP went :tears:

GST
06-24-2005, 06:04 AM
perhaps showing lower than **expected** WHP?

Broken hearts after spending dough on Uber-Engineered-Eleventy-Billion power packages??


:lol: :lol: :lol: No. Maybe ask them if they had their dyno calibrated themselves or by Mustang. I already know the answer. They were too cheap to spend the $$$. Their load is set too low, so the Evo looks like it is switching to a downhill map and AFR readings are misrepresented, hence people wondering where their WHP went :tears:

Actually that is incorrect.

Our dyno was setup and tested by Mustang both inhouse at their own facility and then verified by a field engineer of there's who actually stopped by again not so long ago and tested again, but hey thanks for the laugh this morning anyway!

This is quite laughable really when people complaining of poor numbers/afr's had there cars dyno'd on the same day as other Evo's that had decent numbers/afrs, what the dyno selectively decides to run some cars poorly LOL.

Mike

GST
06-24-2005, 06:08 AM
Their load is set too low, so the Evo looks like it is switching to a downhill map and AFR readings are misrepresented, hence people wondering where their WHP went :tears:

Downhill map under WOT?? HAHA nice one.

Your statement explains why Leif's car ran the AFR's it was tuned to and made the power it should on the same day how??? or the Bozz/Cusco Evo that made the same power it was tuned to on a Dyno Dynamics on our dyno and at the same AFR it was tuned to???

nebolic
06-24-2005, 09:17 AM
it is nice to know that gruppe-s' dyno is fully calibrated by mustang dyno and all aspects of the dyno is working correctly.

nebo

nebolic
06-24-2005, 11:10 AM
on a side note,

I talked to the tech support at Mustang Dyno. They said that there is a fee associated with calibration and sometimes customers who purchase their dyno do not pay that fee (since it is quite expensive). And as far as field engineers going out to check on dynos, it is a paid service fee . . . meaning its not free. Hope that clarifies any questions for people. Also, Mustang Dyno cannot confirm nor deny any calibration done to their dynos until they pull up the original purchase order.

About AFR's, its an add on unit to their system, Mustang has their own unit and also they have aftermarket ones that work with their dyno, again, it requires calibration and there may be a few point of contention where the unit can read AFR's differently and also of course if not calibrated, will read different.

nebo

GST
06-24-2005, 11:19 AM
That is somewhat correct, the initial setup calibration is part of the purchase of the main unit as it's built and calibrated at Mustang using their in house equipment and a test car (a Viper) any subsequent visits by Mustang personal must be paid for unless they are visiting on a courtesy visit when in the area for other reasons (we have had Will from Mustang stop by more than once when in the area).

With regards to AFR, yep 100% agree which is why we have no fewer than 2 replacement 02 sensors new and ready to go at anyone time and replace them every 3-4 weeks regardless (have a look at the side of our dyno machine there is a stack of them) we also fresh air calibrate the O2 sensors at least once a day.

Mike

smack
06-24-2005, 12:09 PM
hey mike,
just wondering how far off are the a/f's from the tail pipe on cars with cats as opposed
to running a test pipe or high flow. if there is a difference, have you found there to be an
across the board offset or is it something that would change based on load or rpm?

thanks
sean

Gruppe-S
06-24-2005, 12:43 PM
Hi guys,

There's no doubt our dyno reads lower than many of the dynojets and various other dynos are the market. Most 4-wheel connected (unlike Dynojets which are not connected or loaded) dynos read about the same - case in point Shiv's Dyno-Dynamics, which reads virtually inline with ours. I will now respond to the specific points

1. Calibration - Dyno calibration is done in-house at Mustangdyne. They have a Viper to do this (at least that's what Beth Heier and Michael Caldwell told me if you're interested in buying a dyno give them a ring they are nice people) - essentially you are spinning up the dyno, measuring the parasitic losses, and using that for calibration.

2. AFR - Our AFR system was provided by Mustangdyne. The AFR is fairly accurate at full load (we have many customers running many different types of WB02 such as PLX, Techedge, etc.) as we often compare these numbers with WB02 units installed in the vehicles. There is some variation in partial throttle and low RPM (less than 2500 rpm) readings, probably because the sniffer is located in the tailpipe, but under full load WOT, it is very rare to see more than a 0.1 AFR differences in the on-board units and our dyno.

That being said I want to explain why and how AFR's will differ from dyno to dyno to street. Unfortunately AFR differences is purely a symptom of poor loading. On an unloaded dyno, such as a dynojet, you will generally see a very high AFR ratio. Just like driving downhill (there is no "downhill map" LOL) - the load on the engine is less which causes the ECU to trim fuel as per engine needs (less load = less fuel required). I personally have tuned my WRX to a table flat 11:1 on a dynojet, only to get on the street and run (to my dismay) 12.4:1. But the real result of this is often many "tuners" who do not understand these differences will tune cars to what they deem to be a reasonable AFR on a dynojet, say 11.0:1, and then when placed on the street or on a loaded dyno will run excessively lean.

On our particular dyno, because it is a loading dyno, we are able to select a particular load for tuning. We generally start at 3400lbs (car + loaded weight + safety margin) but we will often increase the load substantially to ensure that in all conditions (such as WOT hill climb) are accounted for. When this is done properly you will >NOT< see visible difference between dyno tuned AFR and street AFR. Guys - this technique of varying the load is really the only way to obtain a safe and accurate AFR - especially on competition cars - given the myriad of different loading conditions a car encounters. We can proudly say that a race-prepped WRX that we tuned (and helped prepare) won the US Touring Car Championship race at Buttonwillow 3 weekends ago. The tuning time? More than 10 hours, with many many load variations (and yes of course trackside fine-tuning). Guys, if you're going to self tune your car, please please do it on a loading dyno. :)


3. HP Numbers - Yes, our horsepower numbers are low often relative to the higher numbers that are seen with some other dynos. But I guess the question really is - Did we modify our settings to LOWER our readings, or did the other dyno owner recalibrate their settings to read HIGHER numbers. I'm not really sure of that answer (no dyno owner is going to go out and admit that) but I would imagine the latter would make more sense. :P

That being said, I would say our numbers are all in-line relative to the factory HP ratings.

WRX - ~160whp (Factory 227)
STI - ~225whp (Factory 300)
EVO - ~210whp (Factory 280)
350Z - ~210whp (Factory 287)

Guys, we have absolutely nothing to hide! We are confident our dyno works, is accurate, and is an excellent tuning tool!

I just hope the bay area EVO community will feel the same.

I propose we hold a free dyno day with an independent observer to ensure that no setting calibrations are made for the EVO community to lay to rest all speculation and rumors.

What do you guys think (we will bring out the BBQ grille)? :)

Thanks,

Gary
Gruppe-S

Gruppe-S
06-24-2005, 12:49 PM
Hey Smack,

On my WRX, I was using the Helix catted downpipe, before going to GT30R. The WB02 (techedge) was placed 6 inches down from the turbo, and the AFR between the sniffer and the on-board unit was virtually identical. The only real difference being that the response in my on-board AFR was poor (did not detect spikes) as the sensor is getting fairly old (2 years+)

Cheers,

Gary
Gruppe-S

EDIT: As Mike said there usually is a difference in stock cats, the Helix high-flow is a full metal substrate unit, as honestly, it allows a lot to pass through ;)

GST
06-24-2005, 12:52 PM
hey mike,
just wondering how far off are the a/f's from the tail pipe on cars with cats as opposed
to running a test pipe or high flow. if there is a difference, have you found there to be an
across the board offset or is it something that would change based on load or rpm?

thanks
sean

Typically a couple of points variation under WOT conditions on a catted car although it can vary depending on condition of the cat(s).

Mike

earlyapex
06-24-2005, 01:04 PM
Hey Mike,

Can I get some more dyno time so we can tune my...

downhill map?


Their load is set too low, so the Evo looks like it is switching to a downhill map and AFR readings are misrepresented

http://www.millan.net/anims/giffar/giffar2/flowercow.gifhttp://www.millan.net/anims/giffar/giffar2/flowercow.gifhttp://www.millan.net/anims/giffar/giffar2/flowercow.gifhttp://www.millan.net/anims/giffar/giffar2/flowercow.gif

smack
06-24-2005, 02:18 PM
hey guys,
thanks for the info.
fyi, i dyno'd the car at san rafael mitsu 2 days before your last dyno day
and the hp was within 5 of each other but the tq was down ~20 on the mustang
vs. the dynapak(sp?). must be the different way that each load.

oh yeah, do you think switching over to the downhill map earlier will get me better mpg.
you know, with the price of gas these days... :lol:

Gruppe-S
06-24-2005, 02:50 PM
Um...free dyno day + free bbq. Come on guys, lets do this!!! Its more work for me but I guess it will be fun. All we need now is people with differnt tunes......should be interesting to see some nice numbers. :wink:

Tom

MarkSAE
06-24-2005, 02:56 PM
Um...free dyno day + free bbq. Come on guys, lets do this!!! Its more work for me but I guess it will be fun. All we need now is people with differnt tunes......should be interesting to see some nice numbers. :wink:

Tom

Sure. I'll take you guys up for the free dyno day and free BBQ!!

Gruppe-S
06-24-2005, 03:16 PM
Smack - Dynos calculate horsepower based on torque, once torque is determined from readings, there is actually a mathmatical formula that gives the horsepower number. From what I"m told there's a multiplier in the dynapack software, that allows users to accomodate for the rotational mass of the wheels, so the torque being different with the HP being similar could mean that variable has been set differently. The Mustangdyne, because it is a full chassis dyno (and measures torque at the tire rather than the wheel hub) does not have this multiplier (as far as I can tell).

That being said, I think most of the dynos in the bay area read within 20-25whp of each other. The LA guys, I dunno I think there's some fudging going on there. LOL And it's definately unfair to compare numbers outside of California because we're the only ones that have to suffer the terrible Cali 91 octane. :)

Cheers,

Gary

Gruppe-S
06-25-2005, 02:03 AM
We will be holding a Free Dyno day on July 23rd!!!

http://www.norcalevo.net/forums/viewtopic.php?t=4988

Thanks,
Tom
Gruppes
510-783-5300[/url]

methods4
06-27-2005, 08:53 PM
Interesting that airforce1 has not come back to this thread to back up the rumors he heard from the inTARDnet.

You're a winner airforce1!!!!! If you believe everything you read, I have a stock $550 muffler to sell you.

airforce1
06-28-2005, 12:19 AM
:lol: :lol: :lol:

whoa, take it easy guys. If it has to take a Dy-know day to verify the accuracy of the mustang dyno, so be it and hats off to Gruppe-S for it. I was reading couple of threads and was putting two and two together.

http://forums.evolutionm.net/showthread.php?t=145426

http://forums.evolutionm.net/showthread.php?t=141380&page=1&pp=15

Yes, I know someone within the NorCalEvo community that his/her car made shitty WHP. Believe me, it was blatantly obvious. Which, was why I stated what I stated. I have called Mustang Dyno myself and as Nebo stated, Mustang cannot tell you who calibrated what. They just won't reveal it.

The take home message here is: Can I/we take someone's word on whether their dyno is up to snuff? From what I had witnessed, it is obviously NO. Will it take a dy-know day (again hats off to Gruppe-S) to be reassured? Yes, probably. Live and learn guys.

GST
06-28-2005, 01:26 AM
:lol: :lol: :lol:

whoa, take it easy guys. If it has to take a Dy-know day to verify the accuracy of the mustang dyno, so be it and hats off to Gruppe-S for it. I was reading couple of threads and was putting two and two together.

http://forums.evolutionm.net/showthread.php?t=145426

http://forums.evolutionm.net/showthread.php?t=141380&page=1&pp=15

Yes, I know someone within the NorCalEvo community that his/her car made shitty WHP. Believe me, it was blatantly obvious. Which, was why I stated what I stated. I have called Mustang Dyno myself and as Nebo stated, Mustang cannot tell you who calibrated what. They just won't reveal it.

The take home message here is: Can I/we take someone's word on whether their dyno is up to snuff? From what I had witnessed, it is obviously NO. Will it take a dy-know day (again hats off to Gruppe-S) to be reassured? Yes, probably. Live and learn guys.

Well dyno accuracy is somewhat subjective!, all I can say is our dyno provides consistent load based numbers (consistent enough for us to use as the absolute tunning tool for several race cars) albiet our numbers are lower than dyno-jet numbers we are inline with most Dyno Dynamics WHP figures and from what I can tell the AFR readings from properly tuned cars have not been shown to differ between our dyno and the local Dyno Dynamics unit as well as observed on our long term testing vehicles which all use the same wideband device we use for the dyno.

Given the volume of cars we expect during this day we should be able to easily identify the differences in vehicles so if cars with certain mods are performing well and with others are not at least the dyno will not come into the picture as the culprit, unless all the cars perform badly then obviously we've been using a badly calibrated dyno.

Mike

methods4
06-28-2005, 09:38 AM
whoa, take it easy guys. If it has to take a Dy-know day to verify the accuracy of the mustang dyno, so be it and hats off to Gruppe-S for it. I was reading couple of threads and was putting two and two together.

http://forums.evolutionm.net/showthread.php?t=145426

http://forums.evolutionm.net/showthread.php?t=141380&page=1&pp=15

Yes, I know someone within the NorCalEvo community that his/her car made shitty WHP. Believe me, it was blatantly obvious. Which, was why I stated what I stated. I have called Mustang Dyno myself and as Nebo stated, Mustang cannot tell you who calibrated what. They just won't reveal it.

The take home message here is: Can I/we take someone's word on whether their dyno is up to snuff? From what I had witnessed, it is obviously NO. Will it take a dy-know day (again hats off to Gruppe-S) to be reassured? Yes, probably. Live and learn guys.

Why should Gruppe-S take it easy when you're spreading INCORRECT information about their dyno? Like where do you come up with this stuff?


No. Maybe ask them if they had their dyno calibrated themselves or by Mustang. I already know the answer. They were too cheap to spend the $$$. Their load is set too low, so the Evo looks like it is switching to a downhill map and AFR readings are misrepresented, hence people wondering where their WHP went

That is friggin hilarious. Stop trying to put two and two together because it's obvious you don't know how.

Unowned
06-28-2005, 10:21 AM
how much does Car Weight play in effect with the Dyno? I have been to the Fremont Dump Twice now and put down around 3420 and 3460lbs with ME and my GF in the car at the time (Gas weight now). Should we all make a Weight check run for more accurate dynoing?

earlyapex
06-28-2005, 10:41 AM
I was reading couple of threads and was putting two and two together.

http://forums.evolutionm.net/showthread.php?t=145426

http://forums.evolutionm.net/showthread.php?t=141380&page=1&pp=15



Two links to WORKS cars running recockuliously lean on Gruppe-S mustang load-based dyno? How does that prove the gruppe-s dyno is wrong? What's that prove? That those WORKS tuned cars are bad?

How come stock EVO's run normal AFR's for a stock evo (off the charts 10.0 and under) on that dyno?

How come my car ran safe AFR numbers?

How come mikes personal 400+ whp WRX runs safe AFR numbers on that dyno?

How come the cUsc() EVO ran safe AFR numbers on that dyno?

GokuSSJ4
06-28-2005, 11:39 AM
Dynos are usually used most of the time as a tuning tool, to see what differences were achieve with the tuning.
Also having a cat- affect accurate AFR , right !!?? since most of time they use or place the AFR in the muffler. wouldn't the AFR be affective or read differently from some one running a cat, hi-flow cat or a test pipe. not showing accurate AFR the car is running to begin with...

earlyapex
06-28-2005, 11:44 AM
Dynos are usually used most of the time as a tuning tool, to see what differences were achieve with the tuning.
Also having a cat- affect accurate AFR , right !!?? since most of time they use or place the AFR in the muffler. wouldn't the AFR be affective or read differently from some one running a cat, hi-flow cat or a test pipe. not showing accurate AFR the car is running to begin with...

back on the last page:


hey mike,
just wondering how far off are the a/f's from the tail pipe on cars with cats as opposed
to running a test pipe or high flow. if there is a difference, have you found there to be an
across the board offset or is it something that would change based on load or rpm?
thanks
sean


Hey Smack,

On my WRX, I was using the Helix catted downpipe, before going to GT30R. The WB02 (techedge) was placed 6 inches down from the turbo, and the AFR between the sniffer and the on-board unit was virtually identical. The only real difference being that the response in my on-board AFR was poor (did not detect spikes) as the sensor is getting fairly old (2 years+)

Cheers,

Gary
Gruppe-S

EDIT: As Mike said there usually is a difference in stock cats, the Helix high-flow is a full metal substrate unit, as honestly, it allows a lot to pass through ;)



Typically a couple of points variation under WOT conditions on a catted car although it can vary depending on condition of the cat(s).

Mike

GokuSSJ4
06-28-2005, 11:51 AM
didn't bother to read the previous pages :P thanks for the info!!

Gruppe-S
06-29-2005, 03:51 PM
Unowned - Weight absolutely plays a difference on the dyno (please see my previous post about AFR's, etc). You do not need to weigh your car for tuning (unless the tuner does not know how much your car weighs) as when we are tuning the vehicles we will work multiple loads on the car to ensure that different load sites are being properly addressed in the maps.

If you really want to weigh your car however, we have corner weighing scales (for suspension tuning).

The our 2005 EVO with fluids weighed in at 3270 w/o driver. :)
http://www.gruppe-s.com/Promo/corner1.jpg

Cheers,

Gary
Gruppe-s

TarmacAttack
07-06-2005, 01:59 AM
Dynos are usually used most of the time as a tuning tool, to see what differences were achieve with the tuning.

As a tuner I agree 100%. Most of the time I could care less what the initial numbers are. Just as long as I see a gain at the end of the session. 99% of the time test conditions are similar, only in winter time do I get a drastic change. This is why most engine dyno's are good, because you can maintain the test conditions. When I worked for a porsche racing company, I realized the only people that cared for what the numbers actually were, was the magazines. The hardcore track guys all wanted fwhp.

Unowned
07-06-2005, 10:24 AM
Unowned - Weight absolutely plays a difference on the dyno (please see my previous post about AFR's, etc). You do not need to weigh your car for tuning (unless the tuner does not know how much your car weighs) as when we are tuning the vehicles we will work multiple loads on the car to ensure that different load sites are being properly addressed in the maps.

Gary
Gruppe-s

Sounds like i need to patent a dyno with scales so i can sell it to the dyno makers for mad profits :)