OEM backbox restrictive?

[cmhshek]

So I'm thinking of replacing the Spoon N1 backbox with OEM but keeping the Spoon b pipe.

The tegs been mapped with Gruppe M, RBC, DC Sports manifold and Spoon catback already so I'm worried this will lose a few ponies.

Especially after coming across this thread on the TRO forum:
http://type-r-owners.co.uk/forums/showthread.php?77126-Standard-Backbox-15bhp-loss-!

Other than this I can't really find a definitive answer.

Just wondering if anyone has done this and what are people's thoughts?

Thanks,
Chris

 

[MrRy]

At some points he loses 15 LBFT comparing those graphs. I'm sorry but a Spoon N1 backbox alone would not give you an extra 15 LBFT. I would blame that on the tune needing a tweak. I would take that with a complete pinch of salt mate.

I've changed mine back to stock a few months ago but left the Spoon B-pipe on and felt NO power change aside from a little more torque lower down, just much less noise in and out of VTEC. I'm running a stock ECU.

 

[integraleo]

I changed my mapped 3" custom exhaust for my kakimoto regu 06r exhaust and lost 12.5 HP and as much as 20 ftlb of torque at 5500rpm. Both mapped on same dyno with same tuner... Romain. But that's obviously whole exhaust change not just back box, but just goes to show how free flowing a 3" exhaust is compared to a 2.38" exhaust.

 

[cmhshek]

Thanks for your input guys.

Although, if you lost 12.5bhp and 20ftlb of torque when changing from a 3inch system I can't imagine it would be worse with just a backbox as the guy on TRO has said.

I guess I'll just have to try it out for myself and see if I notice any difference.

 

[MrRy]

Spoon N1 and OEM are the same pipe diameter. When offered up they are the same shape. Just the spoon box has a smaller box and it weighs a hell of a lot less.

If someone told me that a Spoon back box gave me an additional 5 LB/FT I would be hesitant to believe them. But almost 15% increase in torque difference at point over the range? Nope. Sorry. That's just what happens when you get rid of the cleverly designed, if restricted OEM ECU that can handle small changes in breathing compared to a map that is specific to that car and that exact setup.

Don't get me started on rolling roads being used as a tuning tool, WHP being the only real way to measure performance, calibrations and more.

Change your back box for OEM and just enjoy the non-intrusive exhaust note mate

 

[cmhshek]

Haha ok thanks mate.

I should be fitting the OEM tomorrow so I'll let you know what my findings are.

 

[Linus27]

I changed back from a Spoon N1 to the OEM back box just two weeks ago and as MrRy has said, I noticed no difference in power and more torque low down. My car has a Spoon b pipe, AEM V2 and K100.

I was really reluctant to change it as I enjoyed the noise but to be honest, I prefer it quieter now having driven it for a few weeks. Before I had a nice scream but it was also mixed with a deep drone like noise. Now it is much purer. Raspy but when VTEC kicks in, it's a lovely scream without the drone.

With the Spoon N1 it made 228 mapped by Romain. I am now getting a Spoon 2-1 decat and remap tweak so a bit more rasp and ponies hopefully. Will be interesting what this new setup will be like. At the end of the day, I just needed it quiter for track so not worried what makes.

 

[cmhshek]

Yeah mate, to be honest regardless of the outcome, think I'll be sticking with the OEM.

The cold starts and drone of the N1 is just too much for me lol.

 

[donzooo]

Yeah mate, to be honest regardless of the outcome, think I'll be sticking with the OEM.

The cold starts and drone of the N1 is just too much for me lol.

That's exactly why I got rid of mine

 

[cmhshek]

Well, I changed them over earlier today and I'm very satisfied with the noise now!

I haven't taken it for a proper drive yet so whether it's lost power is yet to be seen. The exhaust tone is great though, nice and subtle

 

[integraleo]

Even when I lost that 12.5 HP I can honestly say I didn't really notice it so I'm not surprised you don't either.

 

[donzooo]

Even when I lost that 12.5 HP I can honestly say I didn't really notice it so I'm not surprised you don't either.

Although you lost HP at top end it may have increased torque and midrange to an extent making the car still feel quick going up the gears?

 

[integraleo]

Although you lost HP at top end it may have increased torque and midrange to an extent making the car still feel quick going up the gears?

No I lost torque and HP throughout the whole Rev range. Like I said at 5500 rpm I lost 20 ftlb. Not as much all over but still a loss everywhere

 

[donzooo]

No I lost torque and HP throughout the whole Rev range. Like I said at 5500 rpm I lost 20 ftlb. Not as much all over but still a loss everywhere

Mental from just a difference in exhaust. The 3inch must have been mega loud though.

 

[cmhshek]

Had a quick drive last night..may just be me but it did feel less pokey for some reason.

Even so, I'll be keeping the OEM. May invest in a different catback and visit tdi for a tweak in the near future.

 

[integraleo]

Mental from just a difference in exhaust. The 3inch must have been mega loud though.

Yes it was reasonably loud but not ridiculous. I had solid fabrication make it and it came with largest middle silencer that would fit and normal size Rear box. It was the droning I couldn't stand. Hence why I took it off after 6 weeks. It's not all about power when it's your daily.

 

[MrRy]

Apparently 3" is the way to go on a K20, even if just N/A.

I couldn't live with it. I had a custom made mandrel bent exhaust for my DC2 and it was LOUD. Would not have passed any trackdays, even the 105db limit ones.

Once you put a turbo on though, it sounded almost stock.

 

[integraleo]

Ye the k20 does indeed love the 3". I had a turbo dc2 but had buddyclub spec 2 exhaust....that wasn't quiet!

 

[donzooo]

Apparently 3" is the way to go on a K20, even if just N/A.

I couldn't live with it. I had a custom made mandrel bent exhaust for my DC2 and it was LOUD. Would not have passed any trackdays, even the 105db limit ones.

Once you put a turbo on though, it sounded almost stock.

Turbo cars don't generally drone inside due to the air distortion from the blades. Always amazes me when I get a shot of LOUD supras/skylines etc and inside they are as quiet as a road car....almost.

 

[jrscho]

Ye the k20 does indeed love the 3". I had a turbo dc2 but had buddyclub spec 2 exhaust....that wasn't quiet!

That must've been deafening haha!

I don't mind the drone, I have a custom 2.5" and in the near future I want to go 3". Only thing im scared of is neighbours will kill me, I've already had a complaint on my 2.5", would be interesting with a 3"! And this is me driving down my street sitting at 1k revs going 5mph lol