Dyno results from new exhaust system

06redsi · 03-30-2006, 03:33 AM

Ok i finnaly had a chance to dyno the difference the exhaust system made. First off my base run on a dynojet uncorrected was 187whp and 139wtq, this translates to 183whp and 136wtq SAE corrrected, the power difference is SAE corrected #'s so noone can talk smack. the power jumped to 188whp and 144wtq SAE corrected!! with a gain of over 10lbs of tq at 6000rpms!!

. So basically i gained about 5whp and 8wtq and those are the low SAE corrected #'s. this is on a bone stock si with no other mods.
BTW for fun i did a run with the bottom of the airbox disconected form the resonator and i lossed about 10whp and 10wtq , so dont mess with your stock intake or the turbulence with screw with your MAFS readings resulting in a loss of power.

skittleslegend · 03-30-2006, 08:58 AM

THAT'S FANTASTIC!!!!!!!!!

But it'd be nice to know what exhaust you are using

lol.

***twistedframe*** · 03-30-2006, 09:01 AM

thats awesome! good to see our cars don't lose much hp/tq through the drivetrain.

2RotorMotor · 03-30-2006, 09:41 AM

Quote:

Originally Posted by twistedframe

thats awesome! good to see our cars don't lose much hp/tq through the drivetrain.

Its not that, its that our power is clearly underrated....

***twistedframe*** · 03-30-2006, 09:51 AM

Quote:

Originally Posted by 2RotorMotor

Its not that, its that our power is clearly underrated....

oh interesting, i didn't think of that. does anyone happen to know what the real crank horsepower/torque is on the si or do we just have whp numbers.

2RotorMotor · 03-30-2006, 10:06 AM

Quote:

Originally Posted by twistedframe

oh interesting, i didn't think of that. does anyone happen to know what the real crank horsepower/torque is on the si or do we just have whp numbers.

as a baseline guestimate you may add about 12% to the whp. Thats being conservative its usually somewhere in the 15-17%. For example, he said he dynoed at 187 baseline at 12% drivetrain loss that would be about 209 whp.

***twistedframe*** · 03-30-2006, 10:23 AM

Quote:

Originally Posted by 2RotorMotor

as a baseline guestimate you may add about 12% to the whp. Thats being conservative its usually somewhere in the 15-17%. For example, he said he dynoed at 187 baseline at 12% drivetrain loss that would be about 209 whp.

wow i wonder why honda underated it so bad? i mean even saying it had just 200hp would have been cool.

chibianh · 03-30-2006, 10:34 AM

this "15-17%" drivetrain loss was used based on the OLD SAE standards. The new SAE standards used to measure whp was supposed to reduce that drivetrain loss %.

larryd · 03-30-2006, 11:50 AM

Quote:

Originally Posted by twistedframe

wow i wonder why honda underated it so bad? i mean even saying it had just 200hp would have been cool.

It's not really underrated, its the new system which lowered the hp ratings on all cars from the factory.

06redsi · 03-30-2006, 12:46 PM

Oh sorry its a custom stainless 3'' madrel bent exhaust with a magnaflow resonator an a huge dynomax muffler in the back. it looks completely stock from the outside.

nindoo · 03-30-2006, 12:52 PM

Quote:

Originally Posted by 06redsi

Oh sorry its a custom stainless 3'' madrel bent exhaust with a magnaflow resonator an a huge dynomax muffler in the back. it looks completely stock from the outside.

I'm intrigued.
How much louder than stock? Where to look for custom exhausts? You put the stock exhaust tip on?

***twistedframe*** · 03-30-2006, 12:59 PM

3"!?!?!?! that seems way to big for any n/a four cylinder. you do need some backpressure, bigger is not always better. Did you lose a whole bunch of lowend hp/tq? you would have had to with that big of an exhaust.

2RotorMotor · 03-30-2006, 01:07 PM

Quote:

Originally Posted by twistedframe

3"!?!?!?! that seems way to big for any n/a four cylinder. you do need some backpressure, bigger is not always better. Did you lose a whole bunch of lowend hp/tq? you would have had to with that big of an exhaust.

WELL,atleast he's ready for boost...

06redsi · 03-30-2006, 01:20 PM

Quote:

Originally Posted by twistedframe

3"!?!?!?! that seems way to big for any n/a four cylinder. you do need some backpressure, bigger is not always better. Did you lose a whole bunch of lowend hp/tq? you would have had to with that big of an exhaust.

3'' is not too big for a NA K series, in most cases you wouldnt want 3'' on a na 4 banger but i have seen gains anywhere from 8-20whp from switching from 2.5'' to 3'' on NA K series, with proper tunning ofcourse. i gained a steady 5whp and 8-11lbs of tq all the way from 3000 to 8100 rpms so no i didnt loose any power because of the 3'' pipe.

06redsi · 03-30-2006, 01:28 PM

oh any i have a 3 chambered muffler on the back, not a fart cannon. i hate loud hondas

skittleslegend · 03-30-2006, 01:48 PM

Quote:

Originally Posted by 06redsi

Oh sorry its a custom stainless 3'' madrel bent exhaust with a magnaflow resonator an a huge dynomax muffler in the back. it looks completely stock from the outside.

thanks

I'm guessing the Si has 206hp to the crank. It's practically the same engine as the RSX, but it loses 4 hp to the balance shaft in the oil pan.

2RotorMotor · 03-30-2006, 03:33 PM

Quote:

Originally Posted by skittleslegend

thanks

I'm guessing the Si has 206hp to the crank. It's practically the same engine as the RSX, but it loses 4 hp to the balance shaft in the oil pan.

yea, there is no way that a motor with same CR as a b18c5 would have same or less HP. Especially with variable timing which is unique to ivtec and not present on the b series..

06redsi · 03-30-2006, 09:07 PM

here is a link to the dynographs
http://www.k20a.org/forum/showthread.php?t=11519
enjoy

BlackFSIT · 03-31-2006, 06:02 PM

Quote:

Originally Posted by 06redsi

3'' is not too big for a NA K series, in most cases you wouldnt want 3'' on a na 4 banger but i have seen gains anywhere from 8-20whp from switching from 2.5'' to 3'' on NA K series, with proper tunning ofcourse. i gained a steady 5whp and 8-11lbs of tq all the way from 3000 to 8100 rpms so no i didnt loose any power because of the 3'' pipe.

I don't want to start a fight here, but 3 inch is WAY too big for this car. If , for arguments sake, you did gain wheel horsepower with your Exhaust, then with a 2.5 inch setup, you would gain even more. Regardless, your 3 inch exhaust would Maybe give you power up top but completely eliminate the little bottom end you have. Thats great that you think the K20 is special and needs a 3 inch, but its a waste. A three inch is too much for most turbo cars. Let alone a 2.0 N/A motor with NO TOURQUE

mc1200s · 03-31-2006, 07:37 PM

Quote:

Originally Posted by BlackFSIT

I don't want to start a fight here, but 3 inch is WAY too big for this car. If , for arguments sake, you did gain wheel horsepower with your Exhaust, then with a 2.5 inch setup, you would gain even more. Regardless, your 3 inch exhaust would Maybe give you power up top but completely eliminate the little bottom end you have. Thats great that you think the K20 is special and needs a 3 inch, but its a waste. A three inch is too much for most turbo cars. Let alone a 2.0 N/A motor with NO TOURQUE

Im trying to start anything either. I have an Si and love them.
My last play toy was a mustang gt that was built. It had TFS heads, GT-40 intake, E-cam and practically every bolt on you could imagine. I put over 300 to the wheels. I guarantee it flowed and disposed of more air than the Si could with out a large blower.
3 inch exhaust was too big for the stang. I lost about 10 whp when compared to a 2.5 exhaust.

Maybe your added hp came from you removing the restrictive factory muffler???

03-30-2006, 03:33 AM	#1 (permalink)
06redsi Senior Member Join Date: Mar 2006 Posts: 112 iTrader: 0 / 0%	Dyno results from new exhaust system Ok i finnaly had a chance to dyno the difference the exhaust system made. First off my base run on a dynojet uncorrected was 187whp and 139wtq, this translates to 183whp and 136wtq SAE corrrected, the power difference is SAE corrected #'s so noone can talk smack. the power jumped to 188whp and 144wtq SAE corrected!! with a gain of over 10lbs of tq at 6000rpms!! . So basically i gained about 5whp and 8wtq and those are the low SAE corrected #'s. this is on a bone stock si with no other mods. BTW for fun i did a run with the bottom of the airbox disconected form the resonator and i lossed about 10whp and 10wtq , so dont mess with your stock intake or the turbulence with screw with your MAFS readings resulting in a loss of power.

03-30-2006, 09:01 AM	#3 (permalink)
*twistedframe* Tuna Fiddle Join Date: Jan 2006 Location: NoVA Age: 24 Posts: 18,803 Dave iTrader: 9 / 100%	thats awesome! good to see our cars don't lose much hp/tq through the drivetrain. __________________

03-30-2006, 12:59 PM	#12 (permalink)
*twistedframe* Tuna Fiddle Join Date: Jan 2006 Location: NoVA Age: 24 Posts: 18,803 Dave iTrader: 9 / 100%	3"!?!?!?! that seems way to big for any n/a four cylinder. you do need some backpressure, bigger is not always better. Did you lose a whole bunch of lowend hp/tq? you would have had to with that big of an exhaust. __________________

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03-30-2006, 08:58 AM	#2 (permalink)
skittleslegend Senior Member Member Join Date: Sep 2005 Location: Stowe, Vermont Age: 25 Posts: 7,824 iTrader: 1 / 100%	THAT'S FANTASTIC!!!!!!!!! But it'd be nice to know what exhaust you are using lol.

03-30-2006, 10:34 AM	#8 (permalink)
chibianh Senior Member Join Date: Sep 2005 Location: Colorado Posts: 247 iTrader: 0 / 0%	this "15-17%" drivetrain loss was used based on the OLD SAE standards. The new SAE standards used to measure whp was supposed to reduce that drivetrain loss %.

03-30-2006, 12:46 PM	#10 (permalink)
06redsi Senior Member Join Date: Mar 2006 Posts: 112 iTrader: 0 / 0%	Oh sorry its a custom stainless 3'' madrel bent exhaust with a magnaflow resonator an a huge dynomax muffler in the back. it looks completely stock from the outside.

03-30-2006, 01:28 PM	#15 (permalink)
06redsi Senior Member Join Date: Mar 2006 Posts: 112 iTrader: 0 / 0%	oh any i have a 3 chambered muffler on the back, not a fart cannon. i hate loud hondas

03-30-2006, 09:07 PM	#18 (permalink)
06redsi Senior Member Join Date: Mar 2006 Posts: 112 iTrader: 0 / 0%	here is a link to the dynographs http://www.k20a.org/forum/showthread.php?t=11519 enjoy

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