Best exhaust under $1.5k

[monstar]

Oh, the only other thing is that the price listed is with 100 cel cats, with 200 and 300 cel optional.

But regarding the other posts, all that stuff about collectors and megaphones confuses me! But I'd be keen to buy the extractor/megaphone/cat setup as well, would just need it posted!

Yeah forget that eBay link I will price up with 100, 200 and 300 (never seen those) on a group buy of half dozen then.

 

[RED LION]

Sounds good @monstar

 

[Walfers62]

Slightly off topic,

But cheapest place to buy a vcm OTR?

https://www.ebay.com.au/itm/201079289253

 

[monstar]

Slightly off topic,

But cheapest place to buy a vcm OTR?

https://www.ebay.com.au/itm/201079289253

Yes about right. As I mentioned the Orssom is much easier to install and maintain, I've had both.

 

[426Cuda]

O2 sensor fitting bungs are there of course, at a good location, this is a precisely engineered piece of kit. Harness is included with the one linked on eBay, has the HFCs too, the main thing is that's all the bits except still no collector section (secondary pipe).

How to make a megaphone diffuser (collector)
Dimension of the megaphone collector is 2"diffuser expanding to 3.5" for a length of 18.7" from merge point to nozzle at exit wall (past end of HFC substate).
View media item 127Fortunately PH5387 has a mini diffuser already built-in from merge to flange:
View media item 228So 2.25" at merge to 3" at flange exit:
View media item 229Over 12" there is a small expansion to join HFC entry at 3.5":
View media item 227Then 4" HFC barrel and 2.5" exit nozzle:
View media item 214Header flange exit to nozzle at rear of HFC is 16.5":
View media item 225Total PWTB (tuned resonator) volume is 187ci (3.07 litres) per bank:
View media item 122View media item 123Cakewalk for an exhaust bloke worth his salt! If there are three or four members interested I can get a good price to fab up and supply all the headers, collectors with HFCs, ready to install

Legend! I'm very interested, depending on $.

 

[426Cuda]

This whole expansion chamber theory for 4 strokes is new to me. I understand re 2 strokes. The back pressure helps keep fuel air mix in the cylinder on the up stroke, as there are no valves. But, I dont understand how this reverse pulse back pressure helps scavange the exhaust gasses from a 4 stroke? Can you shed some light in the theory Monstar?

 

[monstar]

This whole expansion chamber theory for 4 strokes is new to me. I understand re 2 strokes. The back pressure helps keep fuel air mix in the cylinder on the up stroke, as there are no valves. But, I dont understand how this reverse pulse back pressure helps scavange the exhaust gasses from a 4 stroke? Can you shed some light in the theory Monstar?

Yes mate simply it is an extractor at the end of the primary tubes, not a device at the start near the exhaust port. See diagrams above, and this thread.
Under high thermal load the catalytic substrate creates an air-breathing valveless pulsejet engine, driven by an alternation between high and low pressure. This alternation is not maintained by any mechanical means, rather by the natural acoustic resonance of the rigid tubular engine structure.
It works by alternately accelerating a contained mass of air rearward and then breathing in a fresh mass of air to replace it. The energy to accelerate the air mass is typically provided by the incoming exhaust pulse.

 

[Not_An_Abba_Fan]

Any sort of wave reversion is back pressure, you don't want it on a 4 stroke.

Exhaust pulse tuning can and always has, only been to attain the peak torque at a given rpm range, primary size and length is the ONLY thing that affects this. Having another device further down the exhaust stream does nothing apart from creating an expansion point that terminates the pressure wave. You don't want it reverting and heading back up the exhaust as this is back pressure.

 

[monstar]

Any sort of wave reversion is back pressure, you don't want it on a 4 stroke.

Exhaust pulse tuning can and always has, only been to attain the peak torque at a given rpm range, primary size and length is the ONLY thing that affects this. Having another device further down the exhaust stream does nothing apart from creating an expansion point that terminates the pressure wave. You don't want it reverting and heading back up the exhaust as this is back pressure.

No, there is no reversion caused by this collector. Actually creates propulsion, ie can be measured as thrust...

 

[gavmen]

The discussions above are only for NA applications though correct?

So if I were to go supercharger in future, the gain is a relatively free flowing exhaust?