Who says 3" is 'too big?' (K20 Dyno)

D-Rob · 07-11-2008, 06:42 PM

After a couple months of running around at the 211whp/152wtq power level in my K20A2-swapped coupe, I decided it was time to change something and get a little more pep from her.

So, a friend of mine who had just recently gotten rid of his turbo EM1 offered me his Thermal 3" exhaust at a very reasonable rate.

The results speak for themselves, the 3" exhaust made more power EVERYWHERE compared to the 2.5" ID exhaust that was previously on the car.

The solid line is the 3", the dotted line is the 2.5" exhaust.

Once more, this is a stock internal (from valve cover to oil pan) K20A2, and the only mods are an RBC intake manifold, 11" intake with velocity stack.filter combo, and long-tube Tri-Y header, tuned on K-Pro.

I believe there to be more power in the midrange is I could get some more length out of the intake, as the resonance is occurring much too early.

- Derek

96Spec Ek · 07-11-2008, 06:45 PM

Nice gains, is it much louder? Oh and get that car to the track

D-Rob · 07-11-2008, 06:50 PM

Quote:

Originally Posted by 96Spec Ek

Nice gains, is it much louder? Oh and get that car to the track

Actually, it's not much louder. The muffler I had before was smaller in dimension than the Thermal. It's much deeper, and about the same volume.

As far as the track goes, it trapped 84mph in the 1/8th on my current street tires in 90-degree heat a couple weeks ago at the 211whp power level.

We'll see what the cooler weather this fall does for her, as well as a set of slicks.

- Derek

EKHB · 07-11-2008, 06:51 PM

Thats really nice. Im running a 3" exhuast on my setup.

mar778c · 07-11-2008, 07:38 PM

Don't you know with 3" exhaust you'll lose power.

3" FTW.

koczeka · 07-11-2008, 07:42 PM

Header collector size?

dumafit · 07-11-2008, 07:47 PM

on my k20 setup

i had rbc manifold, short 90* bend intake, rcrew cams, rcrew header, rcrew 3" exhaust, and it made 228whp and 165 torque

3" exhaust on 2.0L

egb18c5 · 07-11-2008, 08:19 PM

this was already proven on k20a.org lol but, its good to see some one post this up on here with a graph. im suprised it made more power throughout the whole graph, i was expecting a slight loss in the lower rpms

BMo Tuning · 07-11-2008, 10:21 PM

Quote:

Originally Posted by mar778c

Don't you know with 3" exhaust you'll lose power.

3" FTW.

"but you can only use 3" on turbo carz"!!!!111!!
lol

I'm glad to see more and more people realizing that is BS. I don't remember who said but I believe it was a header builder who said "anything past the last collector is just a restriction"

Nice gains

2fastGSR · 07-11-2008, 10:29 PM

3 inch ftw

98vtec · 07-11-2008, 10:32 PM

3" + dump =

EL ES DA · 07-11-2008, 11:22 PM

DCacosta · 07-12-2008, 12:18 AM

wow..big gain between 4 and 4.5

Slaz · 07-12-2008, 12:19 AM

Im interested in the collector size also?

Does it go from 2.5 and merge or taper up to the 3in system?

Then i think of all the reverse meagphone set ups that neck down to 2.5 on 2lt + B and K race headers ???

Anyone shed some light on this?

STEEZY_EG+DC · 07-12-2008, 12:34 AM

3" put a 4incher on there and watch the power climb like no other

rebo0t · 07-12-2008, 02:06 AM

3" thermal is what I have as well. I'm glad you did the test, I've been telling customers 3" is actually not too large for a long time now.

benson03 · 07-12-2008, 04:31 AM

sorry to be off the topic. A built b20 will benefit from a 3' exhaust or 2.5' will be sufficient?

mar778c · 07-12-2008, 05:39 AM

Quote:

Originally Posted by benson03

sorry to be off the topic. A built b20 will benefit from a 3' exhaust or 2.5' will be sufficient?

3" > 2.5".

I run 3" on a 1.8L.

D-Rob · 07-12-2008, 06:07 AM

Quote:

Originally Posted by Slaz

Im interested in the collector size also?

Does it go from 2.5 and merge or taper up to the 3in system?

Then i think of all the reverse meagphone set ups that neck down to 2.5 on 2lt + B and K race headers ???

Anyone shed some light on this?

The collector size is actually smaller than 2.5". It appears to be a 2.36" collector, which flares up to 2.5" at the flange. Most 4-2-1 headers don't feature a true 2.5" final collector.

Actually, my exhaust does not make the transition to 3" until about halfway back the car, and still utilizes the 2.5" ID Magnaflow resonator.

- Derek

Slaz · 07-12-2008, 06:31 AM

So from the 2.5 magna flow its just mated flat to the 3in system hole?

No flaring or transition as such?

mar778c · 07-12-2008, 06:52 AM

D,

Thanks for settling this silly debate. I will ask to get this stickied.

D-Rob · 07-12-2008, 06:53 AM

Quote:

Originally Posted by Slaz

So from the 2.5 magna flow its just mated flat to the 3in system hole?

No flaring or transition as such?

There is a 2.5" to 3" flare in place after the resonator.

- Derek

Shadowz7429 · 07-12-2008, 07:13 AM

I wonder if the power would increase if the collector was 2.5" and went into a 3" before the resonator. 3" is the way forward

non of that backpressure bullshit!

ESP.net · 07-12-2008, 07:49 AM

Nice results

This is a pretty much a fact 2.0L+ 3" will gain you decent numbers.

Big Teggie · 07-12-2008, 09:08 AM

Some people will still argue 3" is worthless, even after seeing that graph.

07-11-2008, 06:45 PM	#2
96Spec Ek Honda-Tech Member Join Date: Sep 2005 Location: Long Island, NY Posts: 567	Re: Who says 3" is 'too big?' (D-Rob) Nice gains, is it much louder? Oh and get that car to the track __________________ FS- K24a4 long block slight knock when pulled 350 or best offer pm me!!!

07-11-2008, 06:51 PM	#4
EKHB Honda-Tech Member Join Date: Apr 2004 Location: US Posts: 343	Re: Who says 3" is 'too big?' (96Spec Ek) Thats really nice. Im running a 3" exhuast on my setup.

07-11-2008, 07:38 PM	#5
mar778c Honda-Tech Member Join Date: Mar 2004 Location: PA, USA Posts: 6,133	Re: Who says 3" is 'too big?' (D-Rob) Don't you know with 3" exhaust you'll lose power. 3" FTW. __________________ Good people: Synapse Motorsports,JDogg,b18c1_powered _si,CHEETAH, 86si,NA_is_best, Astig, McNews Automotive, geardog, 4g hatch, Innovative Motorworks

07-11-2008, 07:42 PM	#6
koczeka Honda-Tech Member Join Date: May 2004 Location: Dunakeszi, Hungary Posts: 485	Re: Who says 3" is 'too big?' (D-Rob) Header collector size? __________________ Great: ENDYN, SMSP, Rocket Motorsports, WhoopeeDoo Racing, KingMotorsports, DriveShaftShop, FastBrakes, Crome Pro Regret: F1Spec, R&D Motorsports

07-11-2008, 07:47 PM	#7
dumafit Honda-Tech Member Join Date: Jun 2008 Posts: 1,771	Re: Who says 3" is 'too big?' (koczeka) on my k20 setup i had rbc manifold, short 90* bend intake, rcrew cams, rcrew header, rcrew 3" exhaust, and it made 228whp and 165 torque 3" exhaust on 2.0L

07-11-2008, 08:19 PM	#8
egb18c5 Honda-Tech Member Join Date: Nov 2004 Location: NY Posts: 701	Re: Who says 3" is 'too big?' (dumafit) this was already proven on k20a.org lol but, its good to see some one post this up on here with a graph. im suprised it made more power throughout the whole graph, i was expecting a slight loss in the lower rpms __________________ Perfection is perfected. FS: RS Machine 84.5mm ITR pistons, IB I-Beam rods

07-11-2008, 10:29 PM	#10
2fastGSR King of the One Liners Join Date: Apr 2001 Location: Jersey, USA Posts: 5,406	Re: Who says 3" is 'too big?' (BMo Tuning) 3 inch ftw __________________ AllenBuilt/RSTech Tuned All Motor F2K Coupe: 10.75 @ 127.2 - 2170lbs www.Rstech-Racing.com , www.InlinePro.com , www.ImportDPSonline.com

07-11-2008, 10:32 PM	#11
98vtec Senior Member Join Date: Oct 2002 Posts: 14,226	Re: Who says 3" is 'too big?' (2fastGSR) 3" + dump =

07-11-2008, 11:22 PM	#12
EL ES DA Honda-Tech Member Join Date: Jan 2007 Posts: 64	Re: Who says 3" is 'too big?' (98vtec) __________________ "life's short why drive an ugly car or have an ugly girl"

07-12-2008, 12:18 AM	#13
DCacosta Honda-Tech Member Join Date: Jun 2007 Location: socal, ca Posts: 2,583	wow..big gain between 4 and 4.5 __________________ Integra Type R NHBP #01-0898 FOR SALE -laskey racing racing block 0 miles

07-12-2008, 12:19 AM	#14
Slaz Junior Member Join Date: May 2008 Location: Oz Posts: 86	Re: Who says 3" is 'too big?' (EL ES DA) Im interested in the collector size also? Does it go from 2.5 and merge or taper up to the 3in system? Then i think of all the reverse meagphone set ups that neck down to 2.5 on 2lt + B and K race headers ??? Anyone shed some light on this?

07-12-2008, 12:34 AM	#15
STEEZY_EG+DC Banne*d Join Date: Jun 2006 Location: you know my steez, ca, united states Posts: 396	Re: Who says 3" is 'too big?' (Slaz) 3" put a 4incher on there and watch the power climb like no other

07-12-2008, 02:06 AM	#16
rebo0t Member Join Date: Aug 2005 Location: Oakland, CA Posts: 4,573	3" thermal is what I have as well. I'm glad you did the test, I've been telling customers 3" is actually not too large for a long time now. __________________ FS: CHROME RAYS WHEELS, INTAKE MANIFOLD, CF SEATS, ETC: http://www.hondamarketplace.co...13917 vouches: http://www.hondamarketplace.co...94333

07-12-2008, 04:31 AM	#17
benson03 Honda-Tech Member Join Date: Dec 2005 Location: syndey, nsw, australia Posts: 120	Re: (rebo0t) sorry to be off the topic. A built b20 will benefit from a 3' exhaust or 2.5' will be sufficient? __________________ *BYP Honda Civic Australia** Officially Sponsored by Special Project Motors Lap Record holders: Eastern Creek, Wakefield Park and Oran Park GP

07-12-2008, 06:31 AM	#20
Slaz Junior Member Join Date: May 2008 Location: Oz Posts: 86	Re: (D-Rob) So from the 2.5 magna flow its just mated flat to the 3in system hole? No flaring or transition as such?

07-12-2008, 06:52 AM	#21
mar778c Honda-Tech Member Join Date: Mar 2004 Location: PA, USA Posts: 6,133	Re: (D-Rob) D, Thanks for settling this silly debate. I will ask to get this stickied. __________________ Good people: Synapse Motorsports,JDogg,b18c1_powered _si,CHEETAH, 86si,NA_is_best, Astig, McNews Automotive, geardog, 4g hatch, Innovative Motorworks

07-12-2008, 07:13 AM	#23
Shadowz7429 Honda-Tech Member Join Date: Dec 2006 Location: UK Posts: 2,361	I wonder if the power would increase if the collector was 2.5" and went into a 3" before the resonator. 3" is the way forward non of that backpressure bullshit! __________________ Pm me for any ITR parts enquiries, Ukdm, Jdm.

07-12-2008, 07:49 AM	#24
ESP.net Honda-Tech Member Join Date: May 2007 Location: Puget Sound, WA Posts: 997	Re: (Shadowz7429) Nice results This is a pretty much a fact 2.0L+ 3" will gain you decent numbers. __________________ www.ExplicitSpeedPerformance.net Custom Engineering/Fabrication/Motor Swaps Motor Mount Kits/Traction Bar Systems/Solid 2/3/4 Point Strut Bars/ H22/H23/F20/F22 Alternator/Tensioner Kits/H2B compatible 473hp 373trq 15 psi PumP SC6176e H23AVtec Crx

07-12-2008, 09:08 AM	#25
Big Teggie Honda-Tech Member Join Date: Aug 2001 Location: Umm..., NJ Posts: 4,280	Re: Who says 3" is 'too big?' (D-Rob) Some people will still argue 3" is worthless, even after seeing that graph. __________________ FS: RLZ NA Block, Twin Disc, 6sp Trans, Quaife, Hasport, Fuel Lines, & K Parts Always Updated!

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Who says 3" is 'too big?' (K20 Dyno)