Removing the cat - pre/post dyno graphs

[Elberoth]

The common knowledge is that removing the OE cat - besides triggering the CEL - gives at least 8-10HP.

Tuner's claims are somehow similar (according to their web sites):

Ecode: SOLID 15HP GAIN
ATP: HP gain is 10-15 on stock and K04 turbo.

Well, I decided to check that out.

I got the nice and shiny 2,5" test pipe (I do not want to give any names here, 'cos honestly - I do not belive that any test pipe, be it Ecode, ER, Supersprint, ATP or whatever, would measure any different), I put it at my dealership and went for a ride.

WOW ! The sound itself was worth the price of admission. Car has a nice growl at low RPMs like V8 ... or make that V6.

My butt dyno reported significant hp gain (or at least that was what I thought hearing the nice growl).

So, the last step was to go to the dyno, to find out how much HP did I actually gain (same dyno, same dyno operator, gear, outside temp, fuel etc - only one day later).

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The net resoult is: +0Hp and +0Nm (Nm is metric torque = lbft * 1,36)

LOL



If you look VERY close, there is some improvement in 3-4.5k range (up to 10Nm in one place), but it is nowhere near the advertised HP gains and, in IMO, not worth the hassle (check engine light, smog test problems etc).

Summary:

Test pipe: 200$
Install: 80$
Dyno x2 : 60$
Seeing owner's face after looking at the dyno plots: PRICELESS

[Ptwiggens]

hmm... Ecode did the same thing with their test pipe and got a 15hp gain... can't speak for the others but my car pulled much harder after adding the testpipe. I also think you NEED to include which test pipe it was... despite what you think, they probably do measure quite different.

[|Sandman|]

it may depend on where you´re at, I dunno, but I know for a fact that removing the cat for a 2.5" testpipe (maybe you got the 3" ? I heard the 3" wasn´t very good at all...) will add a good amount of HP to your car... personally I´m gonna add it..

[Elberoth]

This is a 2,5" test pipe.

I also thought that my car is pulling much harder ... and yet dyno told me otherwise.

Butt dynos can be treacherous in general - there are simply too many factors involved that may affect our perceptions (sound is one of them).

[Crazy Quattro]

Good info.

I always thought the test pipe showed bigger gains when going with a K04 or GTRS.

Did eurocode dyno it on the k03?

[3thrd_a_4]

12hp gain with my GTRS kit. Im thinking with a stock turbo the gains may be small.

[EBG 18T]

elberoth - what testpipe did you get? You should have seen better gain than that, unless you were running a 100cell HFC before, or maybe your sportec software isn't designed to work well with a testpipe?

[Elberoth]

elberoth - what testpipe did you get? You should have seen better gain than that, unless you were running a 100cell HFC before, or maybe your sportec software isn't designed to work well with a testpipe?

2,5" outer diameter. One of the more popular ones. As I said - I do not want to call names in this thread, 'cos I do not really belive that any other test pipe would measure any different. I do not also belive that software has anything to do with it.

[Saturnine]

Thats odd..

xonetruthcrewx and i had the exact same setup on both of our Avants, but Colin had the TP and I didnt. He dyno'ed ~10ish hp more than my car did on race gas..

I too have a 2.5" TP and i felt that it made a huge improvment over the OE cat.. The power seems to kick in a little sooner and definetly alot harder than before..

What exhaust do you have?

[|Sandman|]

What exhaust do you have?

this is very important... if you have stock exhaust, that may be the problem...

[Elberoth]

I have a custom made, free flowing 2,5" cat-back exhaust.

[Sydeshow MO]

I have a custom made, free flowing 2,5" cat-back exhaust.

Is there any back pressure at all on this "free flowing custom exhaust"?

[Elberoth]

Is there any back pressure at all on this "free flowing custom exhaust"?

If anything, the lack of backpressure would only affect low end power (but it should increase the top end at the same time).

[Ptwiggens]

I still think it make no sense to not say which one your using... if all the variables were the same with the exception of the test pipe, then post it up. It's not your job to save face for a company whether it be ecode, ER, etc etc...

That being said (after a little digging) we are talking about the Ecode Test Pipe here...

[Howard Hughes]

It's an Ecode test pipe.... who gives a rats...

[|Sandman|]

It's an Ecode test pipe.... who gives a rats...

of course it is, thats why he doesn´t give out the name

[Elberoth]

of course it is, thats why he doesn´t give out the name

Why should I want to save face for that particular company ?

For starters, I'm from Poland, not from the US and I do not know ANYONE from Ecode stuff not to mention beeing friends with someone. I also never did ANY business with them.

As I said, I didn't give any names, 'cos I think that the problem goes much deeper than the Ecode product. I have all the reasons to belive, that ANY 2,5" downpipe would perform the same.

Why it should perform any different ? It is just a straight piece of pipe. No rocket science there.

[Duchenbagen]

Those are pretty interesting results. I know that I picked up some power with my TP but I also added the APR stage 3+ at the same time. LOL.

[Papachristou]

2,5" outer diameter. One of the more popular ones. As I said - I do not want to call names in this thread, 'cos I do not really belive that any other test pipe would measure any different. I do not also belive that software has anything to do with it.

i would have to agree... they are all 2.5" and all bolt to the turbo and then to the DP so what can really change besides metal and welds? its got to help somewhere though maybe with quicker spool up oh well i already got one ill put one tomorrow i hope! this crushes me though :(

[Elberoth]

i would have to agree... they are all 2.5" and all bolt to the turbo and then to the DP so what can really change besides metal and welds? its got to help somewhere though maybe with quicker spool up oh well i already got one ill put one tomorrow i hope! this crushes me though :(

Pls do not be dicouraged by those resoults, LOL.

But serously, if you want - just do it, pls only remember to take the car to the dyno the day before and the day after the installation. I would love to see some more examples to be able to draw some final conclusions.

[Elberoth]

BTW - I'm gonna keep you entertained for the next week. On wensday I'm gonna instal my TIP - I feel next hp gains coming. The next dyno plots will follow ... ha ha ha.

[Doss]

Thanks for the facts Elberoth.

I don't know why ya'll even care who made the pipe. I don't think he's trying to save face or anything... if he doesn't want to name the company he shouldn't have to.

There isn't going to be much of a flow difference depending on company alone (unless the pipe is larger.

I'm think that unless your exhaust was already a restriction (I mean cat), there wouldn't be much gain to be found.

I noticed that most of your gains came where the turbo would've been needing the free flow of a no restriction type set up.

[moto261]

looks like to me the power come on harder stronger and smother then with the stock on

[Howard Hughes]

I don't dispute your claims by any means of making no power with this..... but don't you think it's weird you are the only person it seems to dyno with no gain with the installment of a TP?

[Elberoth]

I don't dispute your claims by any means of making no power with this..... but don't you think it's weird you are the only person it seems to dyno with no gain with the installment of a TP?

Personally, I haven't seen any independent dyno plots of test pipe ONLY.

Most ppl post dynos of chip+TP, bigger turbo + TP, bigger injectors + TP, exhaust+TP etc.

That makes it difficult to find out what exactly contributed to the final gains.

What is more, even If ppl do a test pipe only dyno, they usually go to a different dyno, or compare to a base run made months ago - which itself makes a reading different.

Here we have two dyno runs made in a tightly controlled conditions, day after day.

But as I said - I would love to see other's ppl efforts - but PROVIDED that they will also be made the way I did mine.

[bhvrdr]

Personally, I haven't seen any independent dyno plots of test pipe ONLY.

Most ppl post dynos of chip+TP, bigger turbo + TP, bigger injectors + TP, exhaust+TP etc.

That makes it difficult to find out what exactly contributed to the final gains.

What is more, even If ppl do a test pipe only dyno, they usually go to a different dyno, or compare to a base run made months ago - which itself makes a reading different.

Here we have two dyno runs made in a tightly controlled conditions, day after day.

But as I said - I would love to see other's ppl efforts - but PROVIDED that they will also be made the way I did mine.

I can tell you I dynod back to back the stock cat versus the $800 Milltek/HJS 200cpsi high flow cat and picked up zero power or torque.

cheers! Mike

[Tgr_Clw]

May be true, but I feel that my Milltek HFC did improve the throttle response a bit plus change the exhaust note for the better. Still not worth $800 tho.

[F16HTON]

Tightly controlled conditions day after day?

I guess a 10 degree celcius change in temperature and a 1.3 kpa chang in barometric pressure is tightly controlled?

For us in America, that is a 50 degree celcius one day 70 degrees the next. I do not know about you but I am pretty confident that I pick up 15 whp at night over the day...

1.3kPa is the same as decreasing your boost by 2/10s of a pound.

If you conditions were carefully controlled, you would have actual logs of the vehicle while being dyno'd that show the IAT, EGT, boost, timing and A/F.

[bhvrdr]

Tightly controlled conditions day after day?

I guess a 10 degree celcius change in temperature and a1.3 kpa chang in barometric pressure is tightly controlled?

For us in America, that is a 50 degree celcius one day 70 degrees the next. I do not know about you but I am pretty confident that I pick up 15 whp at night over the day...

If you conditions were carefully controlled, you would have actual logs of the vehicle while being dyno'd that show the IAT, EGT, boost, timing and A/F.

The worse conditions were WITH the testpipe though Greg. If anything he should have showed larger gains no? Of course the dyno computer will at least correct for temp/humidity. I've seen good results from them on stock cars but I wonder about cars who are already making peak boost. Perhaps at that point they are simply reducing EGT a bit rather than gaining as much power as on a stock car? I dunno. Trust me I was upset about the results from my testing also. It actually showed a slight loss in torque and technically worse response (boost came on slightly later) although I considered them a wash as the differences were minimal. Of course my butt dyno was sure I was making power though :(

B7 A4 WITH STOCK CAT...


B7 A4 WITH MILLTEK/HJS 200cpi HIGH FLOW CAT...


Later evaluation revealed that milltek refuses to make any claims for horsepower gain on this unit and therefore refuses refunds on units that show no power made. In essence, they dont claim any power can be made from them, nor does their literature.

cheers! Mike


cheers! Mike

[F16HTON]

I am not concerned with the power rather the statement that there were tightly controlled condtions.

The power he makes with his sportec software in Poland is of no concern to me, what is a concern is that I have seen planty of dyno proof that a testpipe truly makes 15whp on a stock vehicle.

Power adders are not inclusive, if this were the case we could buy everything on ebay, add them up and make 500hp.

223.8WHP is all he is going to make with the K04 and sportec on his car, he has back to back dyno's to show this.

[bhvrdr]

I am not concerned with the power rather the statement that there were tightly controlled condtions.

The power he makes with his sportec software in Poland is of no concern to me, what is a concern is that I have seen planty of dyno proof that a testpipe truly makes 15whp on a stock vehicle.

Power adders are not inclusive, if this were the case we could buy everything on ebay, add them up and make 500hp.

223.8WHP is all he is going to make with the K04 and sportec on his car, he has back to back dyno's to show this.

I can see what you are saying. In this case his K04 setup was maxed like many of our chipped K03 setups and K04 setups are. I think I had the same case on my chipped B7. It hit it's peak and no matter what I was adding it just wasnt helping. I added a full 2.75" exhaust (including 2.75" rear pipes and straight through mufflers) and picked up no power either. One would think that adding a testpipe will always be of benefit and one would think (i know i did) that adding it to a setup that is making lots of power on the stock cat would be one of those situations more power could be made. Apparently not in his or my case. I agree, i've seen it done well on cars running stock boost/ecu (although they seem to boost more after adding the testpipe). So maybe a testpipe is not really all that necessary on cars that are already making max boost? Interesting. I havent seen many back to back dynos of modified cars regarding this.

cheers! Mike

[S4BluDvL]

223.8WHP is all he is going to make with the K04 and sportec on his car, he has back to back dyno's to show this.

That number is a bit depressing.

[Elberoth]

Tightly controlled conditions day after day?

I guess a 10 degree celcius change in temperature and a 1.3 kpa chang in barometric pressure is tightly controlled?

For us in America, that is a 50 degree celcius one day 70 degrees the next. I do not know about you but I am pretty confident that I pick up 15 whp at night over the day...

1.3kPa is the same as decreasing your boost by 2/10s of a pound.

If you conditions were carefully controlled, you would have actual logs of the vehicle while being dyno'd that show the IAT, EGT, boost, timing and A/F.

Greg,

the temp and barometric pressure were almost the same that day/s.

The reason they are different on the plots is that on the first run we have manually changed their values to get rid of DIN70020 correction, which is applied by the dyno software. To get the K=1 (no DIN correction applied), we changed temp to 20'C and pressure to 1013hPa (1013hPa is 1.013kPa not 1.3kPa ) which are the reference values in DIN norm.

During the second run we have left the DIN correction in place. That was a mistake on our part - I agree. We simply forgot about that.

Luckily for us though, what was gained by lower temperature (k>1) was ideally offset by lower pressure (k<1). So even with the DIN correction applied, the K=0,995563 which translated to 0,9hp difference.

k= 1013/P * (273+T/293)^1/2

So instead of 0,6hp LOSS, we in fact gained 0,3hp with the test pipe. Which doesen't change the point of the whole story a single bit if you ask me.

Good attempt, but unsuccesful. At least you have tried though

BTW - I do have logs. Blocks 020, 118 (boost & AIT), 003 (timing & mass flow), 31 (lambda) and 34 (EGT) look almost identical. The mass flow is a bit higher, say 5g/s at higher rpms (>5500), but that can be also seen on the plots as power increase at those RPMs.

[F16HTON]

Why would it be depressing? Power delivery is great, smooth and safe.

[F16HTON]

Greg,

the temp and barometric pressure were almost the same that day/s.

The reason they are different on the plots is that on the first run we have changed their values to get rid of DIN70020 correction, which is applied by the dyno software. To get the K=1 (no DIN correction applied), we changed temp to 20'C and pressure to 1013hPa (1013hPa is 1.013kPa not 1.3kPa ) which are the reference values in DIN norm.

During the second run we have left the DIN correction in place. That was a mistake on our part - I agree. We simply forgot about that.

Luckily for us though, what was gained by lower temperature (k>1) was ideally offset by lower pressure (k<1). So even with the DIN correction applied, the K=0,995563 which translated to 0,9hp difference.

k= 1013/P * (273+T/293)^1/2

So instead of 0,6hp LOSS, we in fact gained 0,3hp. Which doesen't change the point of the whole story a single bit if you ask me.

Good attempt, but unsuccesful. At least you have tried though

BTW - I do have logs. Blocks 020, 118 (boost & AIT), 003 (timing & mass flow), 31 (lambda) and 34 (EGT) look almost identical. The mass flow is a bit higher, say 5g/s at higher rpms (>5500), but that can be also seen on the plots as power increase at those RPMs.

Post up the logs (make graphs for those who are not interested in looking at numbers)

Did you put the test pipe in a stock B6 and dyno it?

The power gains of up to 15WHP by the test pipe makers are based upon stock cars....

If the temp and pressure were the same, there would be no need to change them...

[Elberoth]

Post up the logs (make graphs for those who are not interested in looking at numbers)

Did you put the test pipe in a stock B6 and dyno it?

The power gains of up to 15WHP by the test pipe makers are based upon stock cars....

If the temp and pressure were the same, there would be no need to change them...

If anything, gains on the modded car should be even HIGHER than on a stock car. AFAIR , ATP claims up to 30hp gains on a BT car.

[Elberoth]

223.8WHP is all he is going to make with the K04 and sportec on his car, he has back to back dyno's to show this.

230hp - here I come (after adding the JJ turbo inlet pipe)

[S4BluDvL]

Why would it be depressing? Power delivery is great, smooth and safe.

The amount of power, not it's delivery.

[Tgr_Clw]

Depressing in comparison to what? A stage 2 or higher B5 S4? Or to the 130whp the 1.8T originally makes? Those are very good numbers for a K04 setup.

The amount of power, not it's delivery.

[S4BluDvL]

In comparison to nothing. In consideration of itself.

It was a remark on the car's limitations, nothing particular to Elberoth.