h pipe design

[gumby302ho]

 H pipe exhaust, I first heard about the H pipe when I bought my 87 ford Mustang when I was 21. The little ford 302 made 225 hp stock with a healthy dose of 300 ft pounds of torque, it was the torque that made these little micro blocks kick some serious ass on chevy's bigger 350 motors for a few years. The ford EFI with an injector at every cylinder among other modern changes made this little guy rock, so the exhaust on the little ford had factory installed headers connected to an H pipe. Now you see this H pipe design all over and now its been used on this high end GSXR 1000 header in the picture. The H pipe is a smaller tube that connects the two primary tubes together and helps in performance. I would like to know more from the people in the "know" about H pipe design and why it performs better. It has something to do with equalizing cylinder pressures and or ?

[the fan]

The purpose of the small transfer pipes is basically to allow greater exhaust flow and boost torque at lower RPM.

Depending on engine configuration and firing order the transfer tube allows exhaust gas to flow into the adjoining pipe effectively doubling the flow and offering less restriction. This is due to the fact that the adjoining cylinder is either on the compression stroke, or far enough apart in the firing order that neither exhaust valve is open at the same time. As the flow (engine revs) rises the small tubes carry less and less of the total volume of gas to the adjoining pipe and negate the effect allowing for smoother and higher velocity flow and increased power.

When we were running the R6 in AMA competition we played around with increasing and decreasing the effect to better tailor the power of the bike to what we wanted. The rider we had on the bike preferred a very strong top end bias to the power and we found that while we made the same power at the peak, we were able to come off the corners much faster by restricting the transfer tubes on his Akropovich system. Additional reprogramming of the ignition and adjustable velocity stacks as well as loosening up the slipper clutch made the bike very much two stroke like in its track manners.

Even on the ford V-8 the system works in a similar manner. The small exhaust ports, long intake runners and "H-pipe" contributed to that wonderful low end punch the 5.0 fords were known for. Many modern cars run a 2-1-2 system for this same reason. As the power moves further and further up the revs, bringing the exhaust together can give a substantial low end boost without sacrificing much top end power.

Or I could be completely wrong.

[Firehawk068]

The "H-pipe" design essentially makes the exhaust system larger than it actually is, for better exhaust flow.
On a V-type engine, such as the Mustang with dual exhaust, when the exhaust pulse from one side of the V engine travels to where the "H" crossover is located, it can then split and travel down both sides of the dual exhaust. This results in better exhaust flow.
Also, as a result of this design, under certain circumstances there is a scavanging effect from one side to the other. This also helps with exhaust flow.

Further studies refined the design into an "X-pipe" where better scavanging has been noted.


Due to the lower chassis of the Camaro/Firebird, GM decided that a single exhaust was adequate.
My Firehawk has a single 3" exhaust pipe, and will outflow dual 2-1/2" pipes. At roughly 330 horsepower, the engine doesn't even come close to maxing out the single pipe.  

[aviationfred]

There is a version for the FJ.




http://www.ebay.co.uk/itm/YAMAHA-FJ1100-FJ-1100-FJ1200-FJ-1200-EXHAUST-COLLECTOR-STAINLESS-STEEL-NEW-/151449797360?pt=UK_Motorcycle_Parts_13&hash=item23431c82f0


Fred

[Emporian]

There is a version for the FJ.




http://www.ebay.co.uk/itm/YAMAHA-FJ1100-FJ-1100-FJ1200-FJ-1200-EXHAUST-COLLECTOR-STAINLESS-STEEL-NEW-/151449797360?pt=UK_Motorcycle_Parts_13&hash=item23431c82f0


Fred

I'm wiping the drool off my mouth......

[Arnie]

Ok, its a pretty system being all tubular and polished stainless, but how does this differ functionally from either a stock OEM collector or a Delcavic (copy OEM) collector where all the downpipes share a common volume before exiting from the side connector pipe  connections?

Arnie

There is a version for the FJ.



http://www.ebay.co.uk/itm/YAMAHA-FJ1100-FJ-1100-FJ1200-FJ-1200-EXHAUST-COLLECTOR-STAINLESS-STEEL-NEW-/151449797360?pt=UK_Motorcycle_Parts_13&hash=item23431c82f0


Fred

[Pat Conlon]

I suspect by not much Arnie.
Given the firing order of the FJ's engine 1 - 2 - 4 - 3, if the #1 and #4 were merged together and the #2 an #3 merged, then you would have a better scavenging system (along with the cross pipe to help equalize the pulses)

[Emporian]

$209.00 plus shipping - I'm considering it.
While it might not provide a huge increase over stock, there should be some due to the design being less restrictive.
Seems Randy's headers are all sold out, I'm staying open minded about this one.

[ribbert]

OK, here's another opinion.

I just wrote a long post on this subject and then realised what a can of worms I had opened, or at least dug in to, and the fact it had no real relevance to the FJ, deleted it. It's like an oil thread for techno nerds ( the following is probably even too much  )

As the FJ engine is more tractor than Ferrari, I don't believe there is anything to be gained performance wise. Some even suggest 90 deg "H"pipes impede flow in the adjoining pipe and as far as I know, is not used on most high performance motors, the use of tuned collectors being favoured for the same result.

There are cross over designs specifically made to enhance performance, but my understanding has always been that the "H" pipe is not one of them. I can remember first seeing them on V8's in the late 60's, the idea being that it softened the exhaust noise without the need for further baffling (restriction) which, yes, by default, aids exhaust flow.

Don't forget just how inefficient those great lumps of V8 were in the 60's and 70's. Pissy little exhausts, restrictive 2 barrel carbies etc, highly unlikely they would have been on top of some high tech exhaust flow technology and a joke when you think of the diameter of the single exhaust on a 5+ litre engine most of them sported.

If you leaned over the engine bay and revved one hard you risked having your shirt ripped off your back and sucked down the carbie. At the other end, the exhaust would blow gravel and stones away such was the velocity of the exhaust trying to escape the narrow pipe and the roar (not exhaust note) could be heard a mile away, they were shockers but they did have "H" pipes!

Even at the dealers, we often fitted 4 barrel Webers and free flowing exhausts to some models before they were delivered new. Always left you scratching you head how they could get it so wrong, and this was long before emissions became an issue.

As for the one pictured, I believe there are three and bit simple reasons it has a cross over pipe.

   1.  It holds the two halves together.

   2.  It is cheaper than making a collector (like the original or Delkevic)

   3.  It provides a point for the mount (which has to be in the middle anyway)

   3a.  It takes the hard edge off the exhaust note.

I don't think it's anymore complicated than that.

It is not intended to be a performance upgrade or better than a collector.

Usual Disclaimer

Noel

[TexasDave]

Aarrrrrrgh.      Noel how can you say my FJ is more like a tractor than a Ferrari?  Don't tell me that!  With all the mods I've done to make it handle better and go a little faster I need to think I have a Ferrari. Get my kookaloo every so often at 150mph pretending it's a Ferrari. Now if you said my Hardly was more like a tractor then I could agree with you.     Dave   

[ribbert]

Aarrrrrrgh.      Noel how can you say my FJ is more like a tractor than a Ferrari?  Don't tell me that!  With all the mods I've done to make it handle better and go a little faster I need to think I have a Ferrari. Get my kookaloo every so often at 150mph pretending it's a Ferrari. Now if you said my Hardly was more like a tractor then I could agree with you.     Dave   

Haha Dave, you should be thankful it is! As for the Hardley, well.... it is a tractor.

One of the great strengths of the FJ engine is it's simple, under stressed design.

(and I did say the motor, not the bike)

Noel

[yamaha fj rider]

Funny how most of the OLD tractor companies have two names. John Deer, Massey Ferguson, Alice Chalmers, International Harvester.

Kurt

[PaulG]

Aarrrrrrgh.      Noel how can you say my FJ is more like a tractor than a Ferrari? ....

FIAT owns Ferrari (or used to up til it's public offering of their shares last year)

FIAT also makes tractors    https://www.google.ca/search?q=fiat+tractors&source=lnms&tbm=isch&sa=X&ei=rV74VJrKLZCZyASp_YDICw&ved=0CAcQ_AUoAQ&biw=1366&bih=672


Therefore Ferrraris' ARE tractors

theres simple (minded) logic for ya'   

So what would plow a field better, an FJ or a Ferrari?

[Pat Conlon]

Why settle for a H pipe design when you can have a X pipe....but wait there's more: For a limited time you will also get an Acoustic Supercharger..

Wow! http://www.x-pipe.com/motorcycle.html

"...Campbell X-PIPE™ exhaust! It changed everything. 1. Tuning is not based upon head pipe length and can be dynamic. 2. The power band is much broader because scavenge is not lost at low rpm and back pressure is not produced at high rpm. 3. A high performance engine will not be over-scavenged because the Campbell X-PIPE™® Acoustic Super Charger® exhaust does not need to create and maintain suction to work. 4. Without over-scavenge, engine mixture does not vary between too rich and too lean and back to too rich as rpm increases. 5. High compression pistons are not needed because dynamic cylinder pressure is not lost. 6. High octane fuel is not needed because high compression pistons are not needed. 7. Special 4into1 cam shafts are not needed because additional exhaust duration is unneeded and wasteful.

(* Although not needed, these items can be added to the Campbell X-PIPE™ exhaust for improved performance.)

So, where does the HP come from, with the Campbell X-PIPE™ exhaust? The engine is more thermodynamically efficient (it generates a greater dynamic cylinder pressure while using a longer, more efficient power stroke), it is more fuel efficient (due to reduced over-scavenge) and it works with fewer engine modifications. As a bonus, since the Campbell X-PIPE™ exhaust can work with a short duration exhaust cam (allowing a longer power stroke) exhaust gas temperatures (EGTs) are cooler. Cooler EGTs can allow the tuner to lean the mixture to make even more power, on less fuel!

The Campbell X-PIPE™ exhaust is not a something for nothing device. Rather, it gives you what you thought your 4into1 promised: More Power, Everywhere! In addition, the Campbell X-PIPE™ exhaust gives you a broader power band and greater fuel economy...."

[Pat Conlon]

It is interesting to note the location of these balance tubes ^^ connecting #1-2 and #3-4.
The GSXR also has the same firing order as the FJ (1-2-4-3)
So the waves of gas are close together in those pairs of headpipes.