Plenum/Runner technology.

[build it]

This thread is aimed at discussing intake design and in the less than perfect world of HD, all inspired by a member here.

The most accessible plenum technology I've come across is the G Extreme from S&S. Top builders like them, and they appear to tune well and with relative ease. Somewhat comparable is the cross ram manifold Hillside has been cutting for a number of years, again, works well, simple and elegant, the design worked so well that it was stolen by a number of builders.

Don, with my badgering, pointed me in the direction of Mert Lawill. This seems to be the solution to running an IR setup and being successful, I could be wrong on that. I couldn't find the final results of Roland's testing, but it appeared that they used to small of a carburetor to fit the bill. Tuning would have likely been easier if he didn't change so many things between sessions. 

Then there is another option, significantly more expensive, and I've heard of no one who has done it, not even in the racing world; the setup w ould require two front or rear heads, a common plenum, and independent runners.

So my question is, if the common plenum lacks tuning capacity by and large, why not run independent runners, a common plenum, and some sort of velocity stack pre runner; this wouldn't stick out as much as a G Extreme setup, and the formulae used in the auto world might be of some help? You could easily mount a monstrous t/b or carb on the the end of it and mount the filter between the fork and frame, which would also negate the size problem as it wouldn’t be a problem using, if necessary, a massive air filter element, in front.

Aesthetics aside, wouldn’t this type of approach return a huge amount of tuning potential found in more common intake examples?

[Don D]

http://home.earthlink.net/~redcat/pulse_ram/intro.htm
Read this article for a better description of Ram Pulse tuning.
We would see more of this on the HD if it could be effectively packaged IMO but room and the "look" prevent that (with the exception of the V-Rod). Unless someone designed a Hemholtz, haven't seen that yet, maybe Ed E. had one hidden in the Dyna.
Roland had success with twin S&S IR setup on a sporty many years ago, big power and no loss of low end torque.
I admit bias from my years very long past messing with Mercedes 300SLs and the 2L German Ford motor and Webers.

[Admiral Akbar]

That experimant looked interesting until I real this..

With the final manifold design fully developed, the team then evaluated its effectiveness in terms of improvement over the stock system. Of course, the best method of evaluation would be to construct a prototype and repeat the dynamometer test with the new manifold in place. Since time constraints did not allow such methods, the system was evaluated according to its expected performance.

Too bad.. Without experimental data to back up the theory, it's all pretty much a pipe dream.. 

Max..

[Admiral Akbar]

BTW,,

What is "G extreme"? Link?

Max

[build it]

Hey Max the G Extreme is what PW is running on his bike; common plenum, two G carbs. You can see it in the S&S Catalogue.

[build it]

Max,
I'd suspect that there is plenty of scientific data and modeling techniques readily available. I just can't find anyone who has done it with a V-twin HD. The car guys get this, and because their motors are covered up they don't worry so much about how pretty it is . I recall a builder saying that long runners aided torque while short ones aided the top end charge, obviously a generalization, but the man who said it builds very serious power in the turbo world.

Roland's testing anticipated a streetable 150+ft/lbs out of a 113 engine. Although, that was with an IR setup. This, log style manifold and runners, in theory of course, has the potential to restore ALL of the intake tuning we're missing out on. Depending on how you put it together, it might not interfere with the rider seating position at all.

[Don D]

one more link
http://books.google.com/books?id=aSKzZIqCk54C&pg=PA28&lpg=PA28&dq=4th+pulse+intake+tuning&source=bl&ots=P2g7EPolvx&sig=hzqKjpQoVxFk0Ym3zxeGlLF4IHc&hl=en&ei=v861TJeBFIyssAPs4J2TCA&sa=X&oi=book_result&ct=result&resnum=1&sqi=2&ved=0CBIQ6AEwAA#v=onepage&q&f=false

page 28

[Admiral Akbar]

Ahh yes,, the ship captain's book..  Shows you can learn a lot off the internet while snowed in, in Seward AK...

Bought the book, about 1/2 the way through it..

Max

[Don D]

True divorced IR will force much larger carbs than would seem sane for a single shared plenum motor. This motor has special STD heads to accommodate the dual carbs. There was a limited production version of this bike sold with dual CV40s, not exotic or fussy.


[attachment removed after 60 days by system]

[pwmorris]

Cool-
looks alot like Mike Logsdens 1979 Sputhe Bonneville bike set up.
Remember, these set ups have to be "streetable" for a daily driven street bike. They have to be smooth, have crisp throttle response to red line, and have to be easily tuneable. Alot easier to tune for WOT and dump fuel into the set up. Street set-ups take alot more finesse.
By adding the XXX full mods on my street set up I have it all now. Putt putting around town, nice mid range transitions on open roads and freeways, and massive HP up top.



Baisley has always loved IR's-He likes very short manifolds to the head-




Here's 4 Lectron carbs-2 short "Y" manifolds then into each head-4 carbs total.

[build it]

 this is something I've yet to explore in detail, so I'm "half baked" on all fronts. What I was initially thinking, with significant "inspiration", was to use 2 front heads similar to the XR750setup, and rather than have the two runners stand alone with their own individual carbs, have them merge in a common plenum, with the velocity stacks or Novi stakes mounted inside of the plenum, the plenum would face forward and have one single auto carb or auto T/B on the end with the filter on the end of that. The only way I can see this working now that I've looked at it is if I could get the exhaust system to be on the left side of the bike. Not an easy proposition, and would likely make for significant frame modification.

The other option would be to use two front heads the same way Mert Lawill did, but only use 2 S&S carbs, either G's or heavily modified D's. This setup would have the carbs mounted on the end of the totally individual runners, and the air filters mounted on the end of the carb. This would likely leave me more room to keep the exhaust on the same side of the bike, maybe not?


 

[build it]

My initial findings are that this IR setup can be very hard to tune, but yield far superior results compared to a common plenum, short runner setup like the S&S Extreme setup, if the carbs are on either side of the tank the tuning becomes more difficult than keeping them on one side. I think the biggest problem would be the packaging of the exhaust, wouldn't be as much of a problem if it hung off the left side of the bike.

[build it]

Those stacks wouldn't work with an air cleaner mounted on the end of them, absolutely beautiful pieces though.

[Don D]

There is one rather significant disadvantge to IR and that is the manifold length. We already have what is far less than ideal length with the stock and other manifolds that fit in the V but to gain the full advantage of the IR and ram pulse tuning we would actually need manifolds that are rather long to tune for the RPM range the motors work best in, even when heavily modified. They will still work well with the shortys. Fourth pulse is possible and not impacting the rider with junk hanging out and in the way. One hint about the IR setup and tuning, it pays to play with a balance tube, a small hose and metering orifices to tie the cylinders together to slightly dampen the pulsation. This tube becomes a tuning device. Also certain carbs will not lend themselves to IR as they are too affected by manifold pulses.
Another good read
http://www.visi.com/~moperfserv/buell.htm

[build it]

Don,
I ran across that piece doing a search. It seems they had heat and tuning problems. I'm also not sure if this testing was ever completed showing it viable for street use. It is interesting how the automotive guys love IR setups, even the high end european cars are using IR setups now.

[EngineNut]

Here is part of a response to a post on another forum that explains how the Harley racing department when from the single carb 'Y' manifold used on the 1970 Iron XR750 to a two front head, dual carburetor, 1971 Iron XR750.

A statement was made in a post that said… “Honda DID cause HD to make the inlet ports smaller instead of the "too large" that they were until Honda came along”. Read below and you will see that while some may have believed this to be true, it was not an accurate statement.

Here is some history on the engine design approach the HD racing department used in development of the 750 V-Twin.

The smaller port philosophy actually began in 1970 during preparation for the 1971 Dayton road race. This was thirteen years before Honda’s RS 750 came out, not after.

The 1970 Iron XR 750 suffered from major horsepower loss and engine failure due to excessive engine heat. With the large valve sizes and the production Sportster’s included valve angle of 90 degrees, the piston had an extremely high dome. This resulted in a long flame path and required 50 plus degrees BTC of ignition advance for max power. The longer the fire is lit the hotter the parts will get. This was especially troublesome down the long back straight at Daytona. Something needed to be done to have any chance at a win.

The engine had been previously approved in 1970 and therefore could only be modified without any changes to the approved castings other the machining. If new casings were needed, they would have to build 200 complete XR 750’s and get them approved to be able to race.

Matt Kroll (Project Engineer), John Pohland (Engineer) and Peter Zylstra (Design Engineer) proposed major modifications to the existing iron engine using good engineering processes. Examples were the port and valve sizes as well as the combustion chamber shape.

They started by using two front XR 750 iron cylinder head castings.

The intake valve size was changed from an 1 15/16” (49.2mm) down to 1.65” (42mm). The intake ports had tubes welded in that had an 1.38” I.D. (35mm). This allowed two 36mm (1.456”) Mikuni round slide carburetors to be mounted on rubber hoses. These both were rear facing on the right side like the current Alloy XR 750.

The exhaust valve size was change from 1 ¾” (44.5mm) to 1.38” (35mm). Exhaust pipe diameter was changed from 1 ¾” (44.5mm) O.D. to a thin wall 1 9/16” (39.7mm) O.D., 1.5” (38.1mm) I.D.

The front head used on the rear cylinder had the exhaust port welded shut. A new port that exited on the left side of the engine was machined and tube welded in to extend the port. The engine would now have a front down pipe on the right side and a rear high pipe on the left side.

The cylinder mounting side of the head was counter bored to allow the head to sit on the lip that was machine on the top of the cylinder. This resulted in a much shallower combustion chamber. No head gasket was used like on the Sprint.

The spark plug threads were centrally located between the valves. Champion L series (1/2” reach) spark plugs were used. Ignition advance was 35 degrees BTC.

The iron cylinders had the tops machined down to form a lip, again similar to the Sprint cylinders. The bottoms were shortened and machined round with a small flat left that would sit on top of the crankcase while the round diameter would enter the crankcase.

Through studs were used to mount the heads and the cylinders to the crankcase, again similar to the Sprint and carried over on the alloy XR 750.

The connecting rods were 1” shorter at 6.4375” compared to the 1970 XR engines 7.4375”.

Sprint piston forgings were machined to a 3.000” (76.2mm) diameter. The domes were machined to match the combustion chamber design. The compression ratio was only around 8.5 to 1.

At the 1971 Daytona race Paul Smart qualified number one on the Triumph Trident 3 cylinder with Cal Rayborn qualifying second. Calvin’s top speed was only 142 mph compared Paul’s top speed of 157 mph. Cal had a gear box problem on the 1st lap of the race and had to pit to have it repaired. Later in the season, at Talladega with more development, Cal had a top speed of 165 mph and was faster on top speed then the BSA’s and Triumph’s. While running in second place to Steve Baker’s Yamaha, a piston ring stuck in the rear cylinder allowing oil to fowl the spark plug. The engine did win a road race in the US in 1971. It was at Loudon with Mark Brelsford riding. Cal also used this engine in the Trans-Atlantic Match Race Series in England. With Walt Faulk tuning, Cal won 3 of the 6 races and finished second in the other 3 races.

Hope you found this interesting.