New/Modified Header Design?

[DELETED]

DELETED

[TR]

Thanks for the info, and I have heard one and ridden a few. A friend had one with bigger carbs, porting and custom pipes. It made incredible power at higher revs and sounded like nothing else on (or off) the road! TR

[dbrick]

I rode an H2 once. ONCE. My only advice is bring a change of underwear, that thing is scary.
Made my Yamaha turbo feel like a slug, and that was a fast, fun bike.

[dbrick]

Oh yes, the subject...
I think either would work, were it available I would get the 4-2-1 tri-Y, only because it seems to make sense.

[TR]

Sorry for any confusion, as fun as this post was, I'm not in the market for a header - I was responding to the motorcycle stuff.

The old water buffalo was a bike requiring extra underwear. Super fast with terrible handling and braking...

[ppeters914]

I rode on the back of an H2....once. We were coming back to the base at Vallejo (the back gate on 37?) when my friend dropped a gear and pulled the front wheel off doing 70!

Water buffalo can mean only one thing - the old Suzuki 750cc triple (1972-??) I had a '71 Suzuki Titan 500 ($999 new) when I test rode the water buffalo. Immediately sold the twin and bought the triple.

Unreal power at the rear wheel, but went thru chains and tires like crazy. And you ain't kidding about the lousy brakes and handling.....they didn't call it the Flexi-Flyer for nuthin'

Ahhhhh, I loved that bike! Gots an '83 GS1100E now waiting for carb rebuild and tracking down a mystery short.

Oh, yeah, we were talking roadsters, weren't we......

[Daryl Smith]

More specifically, we were talking about headers for the roadster.

TR, we are simply going to have to agree to disagree on the "scavenging" issue, although I don't seem to remember you mention anything about my crankcase scavenging post. No comment on that?
I think you are just toying with us since you mention "physics" yet you seem to ignore the mass and inertia portion of the equation. The exhaust is travelling at high rate of speed when exiting the combustion chamber and will not immediately slow down upon exit when confined to a specific volume in the primary pipe.

ANYWAY, As my first post stated, this thread was to gauge interest in a new header design. Either ALL new, 4-2-1 or 4-1, OR MODIFY the existing design (slightly longer primaries, better collector). Possibly SMALLER primaries (for stock 1600/1500's)

We are limited in length because of the short distance to the frame (which the exhaust pipe will go through).

Moderate, but noticeable gains would be expected over both the existing header and the stock manifold.

IF you might be interested in this UPGRADED HEADER either now or in the future, Please say so.

I'll see if a poll can be set up. Choices:
1. No, Waste of time.
2. Yes, 4-2-1
3. Yes, 4-1, new
4. Yes, 4-1, existing modified
5. Yes, one of TR's physics defying designs (couldn't resist)

I guess I owe you a beer for that one TR. I will try to make Shasta this year.

Everyone, LET US KNOW YOUR OPINION!!

[TR]

With all the posts, I missed responding!

I've never heard of a crankcase scavenging system...When one is used, is there still a breather at the valve cover? Without a breather, the blow-by would start to cause + pressure in the crankcase and push its way out...

All right, scavenging or no scavenging?

Exhaust leaves the chamber, and yes, has inertia, but this gas is rapidly expanding. Expansion is non-directional. I simply cannot believe that the inertia of the flow is greater than the expansion of that same flow (maybe because I am simple?). The inertia has to be tiny (because the mass is tiny) compared to the expansion.

Well, now you have to make Shasta if you are bringing a beer! TR

[dbrick]

I posted this on the roadster mailing list and got no response, ...

Three pages later, and still going.

Sort of on subject, has anyone ever set up a real crankcase vent/pcv valve setup instead of the semi-passive one? I'm working on a cold air intake box (based on a stainless steel spackle pan) and If I can go with pcv valve to engine vacuum, one less fitting.

I was going to put a filtered air intake on the cam inspection cover and a PCV valve where the vent hose goes now to intake manifold.

Would appreciate any thoughts.
Could move to new thread if this is getting long

[hport]

Wow,

Allot of comments on a much needed topic....Keep it going.

The 4-2-1 header is currently the best "street / road course" design. It will give good torque on the low to mid revs, and pull up to red line quite well, but gives up some top end HP to single length header design. The header you choose will depend greatly on what you what from it.
Exhaust scavenging is a very technical topical that all the replies so far have just skimmed the surface on. The sound waves created in the exhaust are responsible for scavenging in part as well, so you see how deep the rabbit hole goes !

I too would like to see a 421 header designed for a 150HP 20U as well as the 16R. I have talked to many people road racing four cylinders, and they too like the performance gained with the 421, for the amount of dollars spent. The 421 will give you better throttle response via torque gain, with low to modarate HP gain for mid range gains.

It all comes down to $$!

2 cents
JC

[dat68s]

I too would like to see a 421 header designed for a 150HP 20U as well as the 16R.

I would just like to see the 150hp R16
Stuart

[ppeters914]

Okay, I've reread this thread several times. All it did was remind me why I barely passed Physics w/ a D.

The thing I think I understand is that a 4-2-1 design is an improvement for us street people. However, all I see is theory and vague terms like "moderate", "noticeable", and the like. So, coming from the cheap seats;

1. What moderate and noticeable gains are we talking about?
2. What are these gains in comparison to?
3. What do these gains cost? A racer may think that $1000/hp is worth it, but not me.

Thanks.

[TR]

Additional questions:

How loud do you want your street car to be?
How durable (will it crack)?

To me, those are somewhat more important than the performance. I used to have a 510 that was so loud, it wasn't fun to drive. I swapped out the entire exhaust only to find that it was the headers that was making all of the noise! Doh...The next time I had them off for repair of the various cracks that arose from time to time, I put a stock header on and the car was much, much quieter.

I've also had headers that were very durable and not loud, all depends on who makes them and how...

[hport]

All,

The 20U I would expect about a 10hp gain up to 5000 revs then not much to red line. The torque gain should be around 10-15ftlbs on a low end bias curve, peaking a mid range . The cost of a well made header is around $ 300- 400, i'm sure they can be gotten for less.
Just type in tri-Y or search MG / british car sites, these guys have been on top of racing four cylinders for years.
The noise factor can be reduced by coatings and wraps if that is a concern.
Bob Sharp made a 16R with 135hp back in the day, 15 more horses...I think so.

Just trying to put some information and ideas out there !

JC

[spl310]

Wasn't Bob Sharp making that HP with SU carbs? If so, then the switch to Solex carbs would help with the breathing side of things. Could get you closer to the 150!