Lost 18whp from putting my stock exhaust on vs my comptech

[02SilverSiHB]

I put my stock exhaust on since I saw that thread and everyone was saying that these aftermarket exhaust aren't doing much for us. Well I have an injen cai, hp header, and comptech exhaust. I put the stock exhaust on and I noticed at first that I had more torque and didn't feel much of a difference. So I decided I'll sell the exhaust and get hondata instead. Forget that! Later on I started to notice how my car was that great in the higher rpms. I also came across against this damn cougar that beat me by a car length. Last week while I had the comptech on, I beat two by a car length. Now different drivers could have a factor I guess, but oh well. I was sick of it and guessing by the old butt dyno. So I called up the shop and begged for a dyno run. The last one I did was just a month ago, same temps, freaking hot as shit and humid. Nothing has changed. Same gas, same rims, same every damn thing. Now the second dyno sheet you will see is with the comptech off and the stock one on. I lossed 18whp and 9 in torque. The air fuel was the same also. You can see at about 5k rpm how I lossed that top end. The only difference is the time. With the i/h/e I was at the shop at 10am, it was still damn hot and the weather channel showed 92degrees that day (June). Today it was 5pm and I actually let my car rest for about an hour and a half..unlike the last time with i/h/e I didn't wait and jumped on the dyno as I didn't have enough time.

Well here are the results

i/h/e in 92 degree weather in June 2003
http://a9.cpimg.com/image/53/FA/21680979-f32c-02000176-.jpg


I/H and stock exhaust in 91 degree weather as it shows on the weather channel by zip code
http://a6.cpimg.com/image/06/EF/21680646-14e7-0200018C-.jpg

So all in all, I am not selling this exhaust, screw that...oh and let the flames begin :D

[EP3_DC5]

Good call man. There is no way that a well-designed, application specific exhaust will lose power in the upper RPM range. Especially with I/H .

Good call on getting the Dyno done, and despite the few lbs/ft of tq that you lose in the lower range, you get it back and then some in the upper RPM range where you need to be anyways to get the most out of the engine.
BTW, your setup sounds great!!!

[TrippZ]

god damn man

i guess aftermarket exhaust it is..

[myeverlovinsir]

hmmm, I would like to say that you should be better off with the
comptech vs. stock midpipe and muff. Reason being is that you
will have better flow without the resonator in place, bar none.
I still think you could benifit from just using the stock muff with
a larger midpipe. You know the size I'm talking about! I would
not expect you to get worst results from using the comptech vs.
stock, but think you may be pleasently pleased with just swapping
out the midpipe. (no resonator) Sounds are good. Your test really
is not proving much, but then again, a larger midpipe will show
better results on the dyno(sans the resonator) compared to stock,
especially with the I/H setup. Do yourself a favor and try out the
midpipe swap with the comptech axle back. I am sure you will have
just as favorable results for alot less money. And still have the
sounds you desire. just my .02 cdn cents. :D

[JSIR]

that is strange, although your air fuel is a bit richer with the stock exhaust, so some air flow changes have occured.

About 3 weeks ago I put on my stock header back on and did a run at the dyno. Power was down as low as 135 whp, it did rise to 140 a couple runs later for some unknown reason. The runs previous to these the car was making 150 whp. I had a hard time believing there could be a 15 whp difference by going back to the stock header. To this day I still dont believe it, so I dont advertise that run very much as I just cant see a header being worth 10-15 whp. But that is what the dyno stated. What prompted me to try out the stock header again was the Import Tuner dyno test. In the last Import tuner test on the k20a3, the DC header added about 2-3 hp on the very top end and lost a few hp in the bottom end and mid range, so I thought I would see what the stock header would do for me. The difference was more than one would expect in the downward direction.

What I think may be happening is that the ecu adjusts itself over a certain number of miles to the setup you have. The long term fuel trim gets adjusted over time. Once you alter that setup the power might drop due to the ecu being set to the previous settings. That might be part of the effect you and I are seeing by going back to the stock parts, the other part is a slight change in air flow.

After running my Comptech intake uninterrupted for a few days now, I am noticing my air fuel ratio numbers leaning out, they are a good bit leaner than previously. Before this I was interupting the process by disconnecting the battery every couple of days as I was fooling around with things and the car was running richer at that time. So i think long term fuel trim has something to do with it. I believe Hondata refers to this in their dyno tuning tips, about unplugging the ecu when dyno testing different parts. My setup is intake, header, stock muffler, 2 inch midpipe, 64mm throttle body. Those numbers were based on corrected hp, the actual hp numbers were even worse in comparison. So overall conclusion is that the ecu plays a big part in dyno run comparisons.

I'm hoping to go back an retest with the HP header reinstalled now.

Joey

[SiBoy]

how come ther's no drastic changes in curves, i mean 18whp is alot

[02SilverSiHB]

Originally posted by myeverlovinsir
Your test really
is not proving much, but then again, a larger midpipe will show
better results on the dyno(sans the resonator) compared to stock,
especially with the I/H setup. Do yourself a favor and try out the
midpipe swap with the comptech axle back. I am sure you will have
just as favorable results for alot less money. And still have the
sounds you desire. just my .02 cdn cents. :D
Not proving much? I think that it proves my comptech is really helping out with the i/h I have. Now if I was to put the comptech on without the i/h I would not have had those results. I'm not going to swap out the comptech mid pipe with a custom one, no one would buy the comptech midpipe, as it bolts on differently than the stock one, thus not saving me money. I don't feel like spending even more money on getting a custom midpipe done and then doing another dyno...more money for a very iffy if I get more power over the comptech.

Also, JSIR, I always reset the ecu on any mods that I do...so fyi, I did reset the ecu. I unplugged the ecu, disconnected the battery, and put the ignition to on, to make sure no power was being supplied to keep the ecu's memory. I then turned the car on, let it idle till warm, shut it down for an hour and then drove around for 3 hours. I did the uninstall/install of the stock exhaust at 9am along with resetting the ecu. I then took off at 10am and drove around until 1pm then went home and made a call to Team Extreme...this is when after driving around, I noticed that the car was not responsive in the higher rpms like it was before. I had an appoitment at 5pm. I left at 2:45pm and got there at about 3:30pm and let the car chill for an hour and a half. Then got on the dyno. Unlike before with the full i/h/e setup, I never let the car cool down and was rushing from work to get to the shop on time...thus the car was heat soaked like a bitch, giving me the 149whp. So overall, I really feel that the aftermarket exhaust helped me. now apexi may not...from that thread, since it is like 2.5" where as the comptech is just near 2.3" I'm thinking that's why that guy in the thread about aftermarket exhaust not helping that guys car. Stock exhaust feels faster than aftermarket (http://ephatch.com/forum/showthread.php?s=&threadid=18304)

[02SilverSiHB]

Originally posted by SiBoy
how come ther's no drastic changes in curves, i mean 18whp is alot
because it's in the higher rpms...you have to look closely at the dyno sheet, the range is different from each, since the 131whp one is low, thus not showing the higher hp numbers on the sheet (on each side), where as the 149whp one has more hp numbers on the sheet (on each side). It's hard to explain, but do you see what I'm saying?

[Civicvtec1ps]

thats interesting
i guess aftermarket exhaust pays off
:D

[02SilverSiHB]

Originally posted by SiBoy
how come ther's no drastic changes in curves, i mean 18whp is alot
I guess a better way to explain it is, the one with 131whp has a dyno sheet that shows hp in 25's....25, 50, 75, 100, 125. The one with 149whp shows a sheet with 50,60,70,80,90,100,110,120,130,140,150,160. If the 149whp sheet was in 25's it would be drastically different looking.

[myeverlovinsir]

Of course, we are just spitting hairs here, your numbers with
the comptech exhaust and I/H are close to what I got on my
origional setup. 154hp and 134tq. Not saying that you wasted
money, and would not expect you to spend more money to
get another needless dyno done to show a midpipe setup on
your axle back. Just wanted to say that there is a cheaper way.
You have already spend your money on the comptech, stick with
it. I just wanted to lend a note to how one might get there and
not have to spend the money on an expensive aftermarket exhaust.

Thanks for the input. We all have our own ways of finding power.;)

[SIxtasy]

If your ECU adjusted to the higher flow of the comptech, and then you swap on the stock exhaust that has a like 1.5" piping inside the resonator..... what the hell did you expect?? I had the HKS on my car and got sick of the attention it brought, so I had a midpipe and stock muffler put on. I noticed better midrange right away, and NO LOSS anywhere. I think the stock muffler with a 2.25" midpipe will cure your cars illz'. Our muffler axle back is the Type R muffler, only difference being the midpipe.....I'm willing to bet HONDA puts hella more R&D into the performance numbers (HP + TQ) on the "R"series cars, then most aftremaket companies.

Stock exhaust = SHIT
Stock/custom midpipe = THE SHIT
Aftermarket = same as above(more expensive)

Get the midepipe, sell the comptech - and enjoy your $300 profit.

Laterz
- Jeffrey:eek: :eek: :eek:

[myeverlovinsir]

Originally posted by SIxtasy
If your ECU adjusted to the higher flow of the comptech, and then you swap on the stock exhaust that has a like 1.5" piping inside the resonator..... what the hell did you expect?? I had the HKS on my car and got sick of the attention it brought, so I had a midpipe and stock muffler put on. I noticed better midrange right away, and NO LOSS anywhere. I think the stock muffler with a 2.25" midpipe will cure your cars illz'. Our muffler axle back is the Type R muffler, only difference being the midpipe.....I'm willing to bet HONDA puts hella more R&D into the performance numbers (HP + TQ) on the "R"series cars, then most aftremaket companies.

Stock exhaust = SHIT
Stock/custom midpipe = THE SHIT
Aftermarket = same as above(more expensive)

Get the midepipe, sell the comptech - and enjoy your $300 profit.

Laterz
- Jeffrey:eek: :eek: :eek:

Yep, you got it! Only thing I could add to your notes is that the
stock resonator is 1-3/8" (very restrictive0. You are on the mark.;)

[JSIR]

A lot of this part testing stuff gets confusing on our cars, it seems if you have one restriction in the system none of the other parts work very well, the sum of all the parts is reduced when you have one restriction. Surely you cant say the Comptech exhaust is worth 18whp, or that my HP header is worth 15whp. All you can pretty much say is that one modified car runs better with the Comptech exhaust as compared to the stock exhaust, and my modified car runs better with the HP header than the stock header. How much the individual parts are really worth can get confusing.

For example on my car, in my previous testing the midpipe made no gains with the stock header and stock intake. Then when I added the HP header there were still no gains to be found. Only after adding an intake I got 12 whp gains. Now I took away the stock header and lost 10-15 whp. It makes no sense other than the flow is dependant on all parts to work well.


BTW, what do they do to get your air fuel ratio readings when you go to the dyno, are they reading of the stock air fuel sensor or do they just sniff the tailpipe ?. The dyno I go to is kinda old fashioned as they don't have that equipment. Although my PDA OBD-2 scanner isnt too bad at reading A/F.


Joey

[EP3_DC5]

Originally posted by SIxtasy
If your ECU adjusted to the higher flow of the comptech, and then you swap on the stock exhaust that has a like 1.5" piping inside the resonator..... what the hell did you expect?? I had the HKS on my car and got sick of the attention it brought, so I had a midpipe and stock muffler put on. I noticed better midrange right away, and NO LOSS anywhere. I think the stock muffler with a 2.25" midpipe will cure your cars illz'. Our muffler axle back is the Type R muffler, only difference being the midpipe.....I'm willing to bet HONDA puts hella more R&D into the performance numbers (HP + TQ) on the "R"series cars, then most aftremaket companies.

Stock exhaust = SHIT
Stock/custom midpipe = THE SHIT
Aftermarket = same as above(more expensive)

Get the midepipe, sell the comptech - and enjoy your $300 profit.

Laterz
- Jeffrey:eek: :eek: :eek:

I'd have to disagree with you a little bit. Honda also has to keep DB levels in mind, when designing their exhaust. So, some HP may be sacrificed there, plus the stock muffler will weigh more as well. Comptech and other companies like HKS etc do their homework as well, but they focus more on power than DB levels, as long as it falls under the 95 db limit of course.

[SIxtasy]

Originally posted by EP3_DC5


I'd have to disagree with you a little bit. Honda also has to keep DB levels in mind, when designing their exhaust. So, some HP may be sacrificed there, plus the stock muffler will weigh more as well. Comptech and other companies like HKS etc do their homework as well, but they focus more on power than DB levels, as long as it falls under the 95 db limit of course.

This is true about DB's ......here in the states. No sound regulations in Japan to my knowledge, they are only limited to 276whp. The weight part is right though, but unless you are buying a titanium exhaust-you are talking maybe a few pounds. Our stock midpipe is the BIGGEST restriction in the whole stock I/H/E system. Hell if someone had midpipe added to stock car and dyno'd it 3 weeks later It would probably show bigger gains over intake/ header. Well, I'm happy with my exhaust. Laterz

[02SilverSiHB]

Originally posted by myeverlovinsir
Of course, we are just spitting hairs here, your numbers with
the comptech exhaust and I/H are close to what I got on my
origional setup. 154hp and 134tq. Not saying that you wasted
money, and would not expect you to spend more money to
get another needless dyno done to show a midpipe setup on
your axle back. Just wanted to say that there is a cheaper way.
You have already spend your money on the comptech, stick with
it. I just wanted to lend a note to how one might get there and
not have to spend the money on an expensive aftermarket exhaust.

Thanks for the input. We all have our own ways of finding power.;)
oh definitely cheaper route with a custom exhuast....especially considering comptech is selling it's damn name most of the time. Your numbers...didn't you have bored TB and hondata gasket (but not the hondata ecu)? I like your torque, maybe the dc header helps in that area? And did you do the dyno in winter or at least cooler temps than my damn Texas temps :(

[02SilverSiHB]

Originally posted by SIxtasy
If your ECU adjusted to the higher flow of the comptech, and then you swap on the stock exhaust that has a like 1.5" piping inside the resonator..... what the hell did you expect?? I had the HKS on my car and got sick of the attention it brought, so I had a midpipe and stock muffler put on. I noticed better midrange right away, and NO LOSS anywhere. I think the stock muffler with a 2.25" midpipe will cure your cars illz'. Our muffler axle back is the Type R muffler, only difference being the midpipe.....I'm willing to bet HONDA puts hella more R&D into the performance numbers (HP + TQ) on the "R"series cars, then most aftremaket companies.

Stock exhaust = SHIT
Stock/custom midpipe = THE SHIT
Aftermarket = same as above(more expensive)

Get the midepipe, sell the comptech - and enjoy your $300 profit.

Laterz
- Jeffrey:eek: :eek: :eek:
I wasn't expecting 18whp from a 4 banger, that's what the hell I wasn't expecting. I don't have an HKS, I have a comptech, it's no where near as loud as a damn HKS, I've had one and know how they are. Where's my loss at? I'm guessing you butt dyno told you no loss anywhere? I have no "illz" about my setup. I just saw that thread about aftermarket exhaust not doing any thing..proved that wrong. I'll keep my exhaust...it will last longer than a custom one...and it's carb. As I'm in the military and in fact will most likely be moving to Cali.

[02SilverSiHB]

Originally posted by JSIR
A lot of this part testing stuff gets confusing on our cars, it seems if you have one restriction in the system none of the other parts work very well, the sum of all the parts is reduced when you have one restriction. Surely you cant say the Comptech exhaust is worth 18whp, or that my HP header is worth 15whp. All you can pretty much say is that one modified car runs better with the Comptech exhaust as compared to the stock exhaust, and my modified car runs better with the HP header than the stock header. How much the individual parts are really worth can get confusing.

For example on my car, in my previous testing the midpipe made no gains with the stock header and stock intake. Then when I added the HP header there were still no gains to be found. Only after adding an intake I got 12 whp gains. Now I took away the stock header and lost 10-15 whp. It makes no sense other than the flow is dependant on all parts to work well.


BTW, what do they do to get your air fuel ratio readings when you go to the dyno, are they reading of the stock air fuel sensor or do they just sniff the tailpipe ?. The dyno I go to is kinda old fashioned as they don't have that equipment. Although my PDA OBD-2 scanner isnt too bad at reading A/F.


Joey
Definitely agree with you on that the comptech doesn't give 18whp, it's because of my setup. I agree totally with the i/h/e needing to be complete for gains. The sniff tailpipe thing...I'm not too positive, but I don't think that's near as accurate as a wide band o2 sensor...do you? Not to sure about that.

[02SilverSiHB]

Originally posted by SIxtasy


The weight part is right though, but unless you are buying a titanium exhaust-you are talking maybe a few pounds.
yeah, there isn't much difference at all in weight for this exhaust. The b pipe weighs the same as stock, only weight savings was the muffler. The stock one was 15.5lbs and the comptech was 14lbs. Not even a few really :D

[EP3_DC5]

Originally posted by 02SilverSiHB

yeah, there isn't much difference at all in weight for this exhaust. The b pipe weighs the same as stock, only weight savings was the muffler. The stock one was 15.5lbs and the comptech was 14lbs. Not even a few really :D

hahaha, I meant that in general about aftermarket exhausts (the weight that is, as little as it may be).
However, I do agree that the stock resonator and mid-pipe would be the biggest bottlenecks in the exhaust. However I still think it would be better to get an aftermarket exahust, for the looks, the longevity, the sound and the pimpness (but the cost is the only thing going against aftermarket exhausts)! =) Unless you get Magnaflow.......hehe jk I just think that it sounds like ass. But in general the K series sounds quite deep and less ricey than B16 engines.

[02SilverSiHB]

Originally posted by EP3_DC5
hehe jk I just think that it sounds like ass. But in general the K series sounds quite deep and less ricey than B16 engines.
yeah, I hear ya! I hear so many b series that sound like ass, even with good exhaust on :( I was so scared mine was going to sound like that...it doesn't thank God...here's sound clips if no one heard them


http://oplnk.net/~mhx/vid/Burninfrom_outside.mp3
http://oplnk.net/~mhx/vid/Smokedum.mp3
http://oplnk.net/~mhx/vid/Speed.mp3
http://oplnk.net/~mhx/vid/Test1.mp3
http://oplnk.net/~mhx/vid/burninrubber_inside.mp3
http://oplnk.net/~mhx/vid/test2.mp3

[glw]

ok, i'll chime in too.

my car was the test fit car for magnaflow and they did dyno's before and after install on my otherwise stock ep.

torque results -
no loss of torque across the rpm range! torque actually was higher by 5-15 ft/lbs throughout the range and peak torque was 9.7 higher (128.0 vs. 117.3).

hp results -
no loss of whp across the rpm range! whp actually was higher by 5-15 hp throughout the range and peak whp was 5.2 higher (143.1 vs 137.9).

i don't know how much hp/torque replacing the midpipe will get you - but the magnaflow cat-back definitely has the gains on the dyno (as well as my butt dyno :D ). it may be cheaper to go this way, but you may be leaving hp/torque on the table.

[Civicvtec1ps]

Originally posted by glw
ok, i'll chime in too.

my car was the test fit car for magnaflow and they did dyno's before and after install on my otherwise stock ep.

torque results -
no loss of torque across the rpm range! torque actually was higher by 5-15 ft/lbs throughout the range and peak torque was 9.7 higher (128.0 vs. 117.3).

hp results -
no loss of whp across the rpm range! whp actually was higher by 5-15 hp throughout the range and peak whp was 5.2 higher (143.1 vs 137.9).

i don't know how much hp/torque replacing the midpipe will get you - but the magnaflow cat-back definitely has the gains on the dyno (as well as my butt dyno :D ). it may be cheaper to go this way, but you may be leaving hp/torque on the table.
sorry for off topic.
how does midpipe for magnaflow. does it hang low at all?
for 7thgen civic (01-03), people had problem with magnaflow piping because pipe hangs too low.im plannig to lower my car and i dont want that happen you know. ;)

[glw]

Originally posted by Civicvtec1ps

sorry for off topic.
how does midpipe for magnaflow. does it hang low at all?
for 7thgen civic (01-03), people had problem with magnaflow piping because pipe hangs too low.im plannig to lower my car and i dont want that happen you know. ;) no, i'm on eibach sportlines and it has only hit once (i was going way too fast for the speedbump). it tucks up under the car really nice.

back to topic. :D

[hamproof]

Ok, here's a noob question about dyno coz' I haven't been to one.

Is it fair to compare a previous dyno run on a car with another done at a different time w/ mods?

I thought dyno are pretty quirky and the same car at different runs will show differences.

Now, is it fair for 02SilverSiHB to compare his dyno run from a month ago with mods and his current run w/ his stock exhaust and claim he lost 18whp?

Shouldn't be do 2 runs back to back to get a better comparison? I mean if he's going to put the title of the thread as "Lost 18whp from putting my stock exhaust on vs my comptech", I would think a better comparison has to be made. Otherwise, other people bolting on a Comptech expects 18whp improvements.

[EP3_DC5]

Originally posted by hamproof
Ok, here's a noob question about dyno coz' I haven't been to one.

Is it fair to compare a previous dyno run on a car with another done at a different time w/ mods?

I thought dyno are pretty quirky and the same car at different runs will show differences.

Now, is it fair for 02SilverSiHB to compare his dyno run from a month ago with mods and his current run w/ his stock exhaust and claim he lost 18whp?

Shouldn't be do 2 runs back to back to get a better comparison? I mean if he's going to put the title of the thread as "Lost 18whp from putting my stock exhaust on vs my comptech", I would think a better comparison has to be made. Otherwise, other people bolting on a Comptech expects 18whp improvements.

Nah man, the exhaust does not give 18whp, this has already been stated. But due to a few factors that much HP WAS lost on THAT day on THAT dyno, you know? But it still obvious that a bunch of higher end HP was lost with the stock exhaust.

[02SilverSiHB]

Originally posted by EP3_DC5


Nah man, the exhaust does not give 18whp, this has already been stated. But due to a few factors that much HP WAS lost on THAT day on THAT dyno, you know? But it still obvious that a bunch of higher end HP was lost with the stock exhaust.
thank you, that's what I'm saying. This guy says that temps don't matter once it's sae corrected?
http://forums.clubsi.com/showflat.php?Cat=&Board=UBB1&Number=2768832&page=0&view=collapsed&sb=5&o=&fpart=1 (mook says it)

I know the exhaust isn't worth 18whp, it's just the i/h/e setup. I'm sure if could maybe be a tad off in accuracy, but that's the best it gets. This shop isn't opened on the weekends and they have other people needing the dyno for tuning, so I wouldn't be able to swap an exhaust out and do back to back comparison....much less am I going again to prove it, I think I've proven it enough :D

[Burgh]

Never trust the good ole "butt dyno" haha. :D The butt dyno is definitely more sensitive to low-end torque increases than high end hp increases.

[chunky]

it's wierd that your a/f dropped so much. from puting your stock exhaust back on. It actually probably has more to do with the resetting of the ECU.

personally, whenever you do a change like that, you have to give the ECU quite a bit of time to re-adjust and re-learn the optimal settings. And I don't just mean a few hours, it can take a couple hundred miles of driving for the ECU to fully make up it's mind on optimal settings.

I don't typically reset my ECU after mods. I just drive the car and let the ECU do it's thing. and after a little bit, the new power makes itself apparent.

[02SilverSiHB]

Originally posted by chunky
it's wierd that your a/f dropped so much. from puting your stock exhaust back on. It actually probably has more to do with the resetting of the ECU.

personally, whenever you do a change like that, you have to give the ECU quite a bit of time to re-adjust and re-learn the optimal settings. And I don't just mean a few hours, it can take a couple hundred miles of driving for the ECU to fully make up it's mind on optimal settings.

hey, well either way, that wouldn't have robbed the car of that much power. The exhaust did help with my setup

[CivicDuty]

Originally posted by chunky
it's wierd that your a/f dropped so much. from puting your stock exhaust back on. It actually probably has more to do with the resetting of the ECU.

personally, whenever you do a change like that, you have to give the ECU quite a bit of time to re-adjust and re-learn the optimal settings. And I don't just mean a few hours, it can take a couple hundred miles of driving for the ECU to fully make up it's mind on optimal settings.

I don't typically reset my ECU after mods. I just drive the car and let the ECU do it's thing. and after a little bit, the new power makes itself apparent.

I agree. It takes time for the ECU to relearn everything. A week
or two at least. 18hp loss is a lot, but once the ECU relearns,
I'm sure it will be much less of a loss. There is no way that
exhaust alone is worth 18hp. I/H/E together is probably
worth 10-18hp.

-Civic Duty

[hamproof]

Hankook tires is having a sweepstake. Their project Si got 10.2hp and 6.1lb-ft torque from DC Sports header and exhaust. Go here to see:

http://www.winhankooktires.com/

[glw]

is the argument here between the benefits of a "complete cat-back exhaust" and "midpipe and stock muffler".

if so, is it really that hard to believe that certain "complete cat-back exhaust" systems could be better than replacing the just the midpipe?

my magnaflow shows about a 13 whp jump over stock at one point (~4900 rpm) during the pull. i know that peak only went up 5.2 whp, but the entire rpm range is elevated. no losses anywhere!

torque had two significant jumps (~2800 and ~4900 rpm) of about 15 ft-lbs over stock during the pull with a peak gain of 10.7 ft-lbs. no losses anywhere!

the pulls were run on the same dyno 1 week apart - one stock and one with the cat-back installed. as i recall they actually totalled about 12 pulls using stock and various designs until they got a design that put out the performance and wasn't too loud.

http://sourcecodegeeks.com//public/civic/images/dyno_sm.jpg (http://sourcecodegeeks.com/public/civic/images/dyno.jpg)

in either case, i don't know what results a midpipe replacement with stock muffler would give... but the complete cat-back exhaust system can put out.

[BlackNRedSi]

Originally posted by CivicDuty


I agree. It takes time for the ECU to relearn everything. A week
or two at least. 18hp loss is a lot, but once the ECU relearns,
I'm sure it will be much less of a loss. There is no way that
exhaust alone is worth 18hp. I/H/E together is probably
worth 10-18hp.

-Civic Duty

Your correct, but if you take that Exhaust off, the I/H isnt going to do too much of anything...if you complete the whole I/H/E then you will see the results, but w/o the missing link wheather its the I/H/E your not going to get your full amount of HP

[02SilverSiHB]

Originally posted by CivicDuty


I agree. It takes time for the ECU to relearn everything. A week
or two at least. 18hp loss is a lot, but once the ECU relearns,
I'm sure it will be much less of a loss. There is no way that
exhaust alone is worth 18hp. I/H/E together is probably
worth 10-18hp.

-Civic Duty
I guess I need to state this again for I don't know, the 5th time. I NEVER SAID THE EXHAUST ONLY WILL GIVE THIS MUCH, ONLY WITH I/H/E WILL THIS BE NOTICED!

and I highly doubt the ecu is killing that much power. My God, the dynos are only a month apart, same climate, same dyno, same person doing the dyno, same everything, just one month apart.

[02SilverSiHB]

Originally posted by glw
is the argument here between the benefits of a "complete cat-back exhaust" and "midpipe and stock muffler".
I never meant it to, but it may be turning into that I guess. I posted this because someone said that aftermarket exhaust don't help, they only rob power...I proved this wrong. I just recently put my comptech back onto day. My God, it's like night and day after 4k rpm.

[02SilverSiHB]

You know what really makes me laugh...this whole: "Well these dynos are really inaccurate since they weren't done on the same day." But yet, I also have to give the ecu this long time to "relearn" the new exhaust system I have.....so which one is it!?

Well, why is it that when anyone else does the same thing, it's okay, but it isn't for me????


Especially when I posted my dyno results that I had in January with a sri and hp header in January...came out to 146whp with a spike at the end because the guy on the dyno hit the rev limiter. But then my dyno in June with i/h/e came out to 149whp and people like to say I paid for a cai and comptech exhaust for 3whp....funny how this all works. Holy shit!


Here's the bottom line...my freaking point. I did this to show the exhaust helps tremendously with the i/h that I have. It does, nuff said.

[chunky]

Originally posted by 02SilverSiHB

I guess I need to state this again for I don't know, the 5th time. I NEVER SAID THE EXHAUST ONLY WILL GIVE THIS MUCH, ONLY WITH I/H/E WILL THIS BE NOTICED!

and I highly doubt the ecu is killing that much power. My God, the dynos are only a month apart, same climate, same dyno, same person doing the dyno, same everything, just one month apart.

you'd be surprised at how much the ecu has to do with it.

the exhaust at most would be worth 8-10hp on it's own, and that's taking into account the synergistic effects of the i/h/e. On a stock motor, exhaust alone would net less than 8hp. As you've mentioned, the parts all work together.

But don't overlook the ecu. The ecu likes to be at close to 13:1 a/f from what i've seen for k20 motors. It will over time adjust the fuel trim settings to accomplish this. your 2nd dyno was showing 12:1 a/f. that's what turbo motors typically strive for. In other words, that's running rich for a n/a motor. The ecu obviously thought that there was detonation risk, which could be due to a number of things including cold engine, high humidity. But the more likely explanation is that the ECU is still re-learning everything that it forgot during the reset. The ecu always runs rich until it re-learns the fuel trim.

if you've got the $$$, go back in a few weeks when the ECU has had time to re-learn. I seriously doubt the losses will be 18hp.

[02SilverSiHB]

Originally posted by chunky


you'd be surprised at how much the ecu has to do with it.

the exhaust at most would be worth 8-10hp on it's own, and that's taking into account the synergistic effects of the i/h/e. On a stock motor, exhaust alone would net less than 8hp. As you've mentioned, the parts all work together.

But don't overlook the ecu. The ecu likes to be at close to 13:1 a/f from what i've seen for k20 motors. It will over time adjust the fuel trim settings to accomplish this. your 2nd dyno was showing 12:1 a/f. that's what turbo motors typically strive for. In other words, that's running rich for a n/a motor. The ecu obviously thought that there was detonation risk, which could be due to a number of things including cold engine, high humidity. But the more likely explanation is that the ECU is still re-learning everything that it forgot during the reset. The ecu always runs rich until it re-learns the fuel trim.

if you've got the $$$, go back in a few weeks when the ECU has had time to re-learn. I seriously doubt the losses will be 18hp.

Well, I agree with you totally on that. I'm not going to go back anytime soon, much less with the stock exhaust. I put the comptech back on.

I'll go back in January, so then it will be a whole year since the dyno I had with a sri and hp header that put out 146whp that hit the rev limiter. I'm hoping that I will have more than the 149whp with the i/h/e I have now and that it will have time to adjust by then. I'll do two runs, one with the rpms going to 6800 and another with the guy hitting the rev limiter. I'm hoping to show there is a slight difference when hitting the rev limiter and that I probably only had 143whp vs the 146whp I had with the sri and hp header in January, here's that dyno

[02SilverSiHB]

TTT for kenis138. I tried replying to your pm to show you the thread, but you inbox/sent items/message tracking is full.