Taco's Crx type R build

[Dual-500]

Well, I don't doubt it at all. I run 2.5" on my ZC and had it on the otherwise stock D16A6 and it seemed to work fine. But, I never tried 2" or 2 1/4" so I don't know. Nor have I compared on a dyno. Just going from past experience with other things - motorcycles, racing karts, dirt bikes, RC racing hydroplanes - both 2 strokes and 4 strokes, gasoline, alcohol and nitromethane engines.

Why I asked, is on some forums, I've seen people go ballistic over it, screaming 3" was way TFB and so on. Lots of them claim 2.5" is too large and there will be hugh losses in the low end. Honestly, I don't think any of them can even spell scavenging let alone understand the concept.

Probably another case of inexperience and just posting what they think or have read - not experience talking - which is what I figured.

BTW: I'm going to a full size dual core radiator in mine - that's why I have the narrow one unused and for sale.

 

[B16]

3" pipe for a NA build?

Yes sir. I did it and am a true believer.

normally used for more top end while the 2.5 yeilds some better power in the low to mid range.

I've seen alot of guys local do it. Especially with K20 swap.

No low end loss, no loss anywhere, only gains.

Well, I don't doubt it at all. I run 2.5" on my ZC and had it on the otherwise stock D16A6 and it seemed to work fine. But, I never tried 2" or 2 1/4" so I don't know.

Why I asked is on some forums I've seen people go ballistic over it screaming 3" was way TFB and so on. Lots of them claim 2.5" is too large.

Probably another case of inexperience and just posting what they think or have read - not experience talking - which is what I figured.

BTW: I'm going to a full size dual core radiator in mine - that's why I have the narrow one unused and for sale.

The ONLY naysayers I've EVER seen were those who are keyboard racers that read such and such on some forum (Not saying you are Taco.lol!). I've never seen proof that 3" loses power ANYWHERE, only gains.

Here is mine. Only swap was rmf narry header from JDM DC 4-1 and 2.25" exhaust to 3" exhaust. Gains everywhere.

 

[Taco15]

way to back up your statement B16

Mod-man, keep in mind every motor is different and makes power and different ranges so while the 3 inch may work for B16 is doesn't mean it will work for everyone.
...unless i get proven wrong here.

the plan is to have a shop build one for me instead of buying one.

 

[B16]

I would love to see a smaller motor compare 2.5 to 3". I vote 3" will still win.

Taco,
I did the same thing. My 3" is muffler man crush bent special. Using 22" long magnaflow 3" resonator and 3" magnaflow chambered muffler. I need to keep sound down for Laguna (haven't tested there yet though). It is nice, quiet and deep too.

 

[Dual-500]

way to back up your statement B16

Mod-man, keep in mind every motor is different and makes power and different ranges so while the 3 inch may work for B16 is doesn't mean it will work for everyone.
...unless i get proven wrong here.

the plan is to have a shop build one for me instead of buying one.

Yes I understand that. Been tuning about 40 years - this is my first Honda.

My experience says B16 is spot on - not to mention the graphs he produced. It's more a case of the gains it will produce and not the losses. Gains produced will be on a case by case basis as you alluded to.

I've seen posts that claim low end losses with the larger tube sizes and have to agree again with B16 - Keyboard Tuners. We had a name for them in the old school days - that kind were referred to as "Trailer Racers". Kinda like your basic Arm Chair Quarterback. They knew everything, yet produced nothing tangible.

The only cars I know of offhand that really tune anything beyond the header is NASCAR. For a street application it pretty much ends at the header - with the exception of course being a case of excessive back pressure from an undersized exhaust system or cat.

 

[UNDR8D]

I would love to see a smaller motor compare 2.5 to 3". I vote 3" will still win.

Taco,
I did the same thing. My 3" is muffler man crush bent special. Using 22" long magnaflow 3" resonator and 3" magnaflow chambered muffler. I need to keep sound down for Laguna (haven't tested there yet though). It is nice, quiet and deep too.

Would a pipe size limitation have anything to do with valve spring rates. I was under the impression that a weaker exhaust valve spring would require more back pressure to help it close on time and avoid float. Whereas, if you have a stiff aftermarket valve train, this would be less likely. Perhaps this another bench racing myth too...?

 

[phunky.buddha]

If you're depending on exhaust "backpressure" to help your valves close because your springs are too weak, you've got a problem... with your springs.

 

[Taco15]

right on.
if i can save and use that RMF header I will. It's just so damn big and now ugly.
currently waiting to hear back from one of our vendors who sels the RMF replica's.

I've seen some Hytec tr-y replica's go for $320 and the build quality looks really good
we'll see

 

[UNDR8D]

Well if all else fails I can build you a super sick bisi-style one out of stainless. I can't guarantee it'll be cheap though lol

 

[hondarin]

Would a pipe size limitation have anything to do with valve spring rates. I was under the impression that a weaker exhaust valve spring would require more back pressure to help it close on time and avoid float. Whereas, if you have a stiff aftermarket valve train, this would be less likely. Perhaps this another bench racing myth too...?

not to mention the fact that the force of the back pressure would be acting in the wrong direction; if your valve springs were weak enough, back pressure would make the valve stay OPEN

 

[Dual-500]

Would a pipe size limitation have anything to do with valve spring rates. I was under the impression that a weaker exhaust valve spring would require more back pressure to help it close on time and avoid float. Whereas, if you have a stiff aftermarket valve train, this would be less likely. Perhaps this another bench racing myth too...?

Myth. That would take a reversion wave at the precise time and well......no. Assuming scavenging is taking place, and that's the basic premise of header theory, as RPM increases the effects of scavenging will decrease. The only exhaust system I can think of offhand that is designed to produce and does produce a reversion wave at the correct time and of a magnitude that could be noticed is for 2 stroke engines - the Resonator or Expansion Chamber.

http://en.wikipedia.org/wiki/Expansion_chamber

 

[B16]

I've seen some Hytec tr-y replica's go for $320 and the build quality looks really good
we'll see

I've "heard" people aren't very happy with the Tri-y's power wise. Just a caution.

 

[Taco15]

I want something that will make the most power at the top end.
Tri-y just looks cooler

working with the vendor to see how the RMF narrow style will work out.
he got back to me

 

[Taco15]

Bam son!
bisimoto style!
Private Label Mfg - PLM Headers & Manifolds

 

[UNDR8D]

not to mention the fact that the force of the back pressure would be acting in the wrong direction; if your valve springs were weak enough, back pressure would make the valve stay OPEN

No

 

[UNDR8D]

Myth. That would take a reversion wave at the precise time and well......no. Assuming scavenging is taking place, and that's the basic premise of header theory, as RPM increases the effects of scavenging will decrease. The only exhaust system I can think of offhand that is designed to produce and does produce a reversion wave at the correct time and of a magnitude that could be noticed is for 2 stroke engines - the Resonator or Expansion Chamber.

Expansion chamber - Wikipedia, the free encyclopedia

Thanks for the info!

 

[hondarin]

No

"back pressure" is the result of less than ideal or turbulent flow; which would never help a valve close.

what you're thinking of is "scavenging." where where exhaust pulses help to "pull" the next pulse through the tube because the flow has good velocity and laminar flow, and there is an area of low pressure between to pulses.

 

[UNDR8D]

Ya that makes sense. I was brain dead yesterday...or maybe everyday...?

 

[Dual-500]

Ya that makes sense. I was brain dead yesterday...or maybe everyday...?

Brain Dead? Most days for me.......

 

[hondarin]

no prob, happens to everyone