Wildguzzi.com
General Category => General Discussion => Topic started by: redrider on March 11, 2015, 02:00:55 PM
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Has anyone compared the power curves and such for a big block running straight headers vs the same bike with the balance pipe up front? I ask because my Norton tuning guide states the balance pipe's sole purpose is noise reduction and should be scrapped in favor of straight headers into a low restriction muffler. The two engines share rpm ranges. And my Sport 1100 does not have one. Curious in Columbia.
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Well someone must have, possibly the engineering dept at Guzzi. The intent of the forward crossovers were to increase mid-range perfomance on the 1100's.
Is there a difference in the output or performance between the configurations...? I cannot swear to it but I personally have not done a pipe swap then dynoed an engine either.
Are ou talking about a current, new version Norton or a Vintage Norton.../
Best,
Rob
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All 4 stroke twins w/crossover use it to flow more exhaust, one pipe into two. As the motor runs, when it fires, it exits in 2 pipes, same for the other cyl.
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All twins w/crossover use it to flow more exhaust, one pipe into two. As the motor runs, when it fires, it exits in 2 pipes, same for the other cyl.
And , a c rossover pipe allows for smaller less restrictive mufflers because of this . Maybe a race tuned engine , with no concern for noise levels will make more top end power on straight pipes running through open mufflers , most street engines won't . Of course , this discussion has started many a heated debate on WG , one ex member who had no experience with engines started sighting internet articles about how all internal combustion engines make more power on open pipes ::)
Dusty
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Fixtit, doesn't apply to 2 strokes as I have seen.
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When Todd@GuzziTech came up with his "crack-proof" headers for the V11 Sport/LeMans he ran them both ways, with and without front crossover, and did not see a measureable difference on the dyno.
At least that's what he told me a few years ago when I was shopping headers for my Nero Corsa.
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I understand the model-pos and neg pressure waves, scavenging and such. If I had the equipment, I would test myself.
So Guzzi uses them to increase midrange but at the expense of low or high end? The 3k dip in power is present in all 3 of mine if you look at the charts. I'll look around for an animated power pulse/flow video.
The Norton tuning is from the old Haynes repair manual ('70's) with the performance section as the last chapter. Kind of rare as the other copy I have omits the section. I've only seen one and I have it.
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I understand the model-pos and neg pressure waves, scavenging and such. If I had the equipment, I would test myself.
So Guzzi uses them to increase midrange but at the expense of low or high end? The 3k dip in power is present in all 3 of mine if you look at the charts. I'll look around for an animated power pulse/flow video.
The Norton tuning is from the old Haynes repair manual ('70's) with the performance section as the last chapter. Kind of rare as the other copy I have omits the section. I've only seen one and I have it.
:D :D :D :D
Yeah , I have a Haynes manual for BMW printed in '75 with a performance tuning section in the back . Some of it is simply incorrect ;D
Dusty
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I think there are two things being presented here -- the FRONT crossover on an 1100, and the BALANCE PIPE concept. I tossed my hydro's front-x-over pipes because they were getting warm all over my atf cooler ('vert content). I noticed no difference. I've also run with no mid-x-over and think the bike feels 'restricted' or 'congested' by comparison.
Has anyone compared the power curves and such for a big block running straight headers vs the same bike with the balance pipe up front? I ask because my Norton tuning guide states the balance pipe's sole purpose is noise reduction and should be scrapped in favor of straight headers into a low restriction muffler. The two engines share rpm ranges. And my Sport 1100 does not have one. Curious in Columbia.
One of the more ignorant things I've read today, but I haven't gotten to the news yet. That's where I generally go when I want to see facts disproved by opinion. :D I hope this is a bathroom book and not a technical reference.
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Oh, it's just 1960s/1970s tech.
Sort of like when you buy a set of long drag pipes, and to find the "optimum length", you go out and run the hell out of the bike.
Get back to the shop, you cut the pipes in a 45-degree cut at the point where the blue stops.
:bike
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Are the power pulses for a Norton vertical twin the same as a Guzzi V-twin? I would think not. Doesn't that render this a false comparison?
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A twin is two singles on a common crankshaft. Getting both to behave as one is an art.
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The front crossover on my Hydro caught my alternator cover when the bolts vibrated off. So, they are at least good for that.
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A twin is two singles on a common crankshaft. Getting both to behave as one is an art.
Just a bit of tuning...not art. A 360 Brit twin and a 90 degree Guzzi respond differently to exhaust systems. The balance pipe location can be varied to change the engine power band up or down within limits of the cam and intake
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This is purely seat of the pants report but a few years back my crossover pipe on my T-3 rusted through. A local muffler shop made two adapters for me to eliminate the crossover and go straight from the headers to my cheap Emego mufflers (snapping suspenders, really need a icon for that) for $15. I Cannot tell any performance or sound difference.
GliderJohn
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The original owner of my 04 Stone Touring put a Stucchi crossover and Mistral "silencers" on it, plus a PC-III with a map by Todd Egan and a Ferracci airbox. I hate loud bikes and removed all but the PC-iii. Found no difference in performance.
Later, as an experiment, I put that Stucchi crossover on my totally standard 03 Stone Touring. Could not tell any difference. Removed it and again, no difference. The one proven advantage with the Stucchi crossover is that gearbox oil changes are a lot easier.
Both bikes deliver a consistent 44-45mpg.
Ralph
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The original owner of my 04 Stone Touring put a Stucchi crossover and Mistral "silencers" on it, plus a PC-III with a map by Todd Egan and a Ferracci airbox. I hate loud bikes and removed all but the PC-iii. Found no difference in performance.
Later, as an experiment, I put that Stucchi crossover on my totally standard 03 Stone Touring. Could not tell any difference. Removed it and again, no difference. The one proven advantage with the Stucchi crossover is that gearbox oil changes are a lot easier.
Both bikes deliver a consistent 44-45mpg.
Ralph
Interesting Ralph . Yes , the only place for loud bikes is at a race track .
Dusty
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On my bike (LM II) there is a crossover both in the header pipes and another under the gearbox. The front XO is so close to the alternator cover that I have to remove the header pipes to remove the cover, that's a royal pita if you just want to check charging. I wonder if it will make any difference if I use plain pipes without the XO.
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I did just that and noticed nothing but lower blood pressure.
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The front crossover on my Hydro caught my alternator cover when the bolts vibrated off. So, they are at least good for that.
It caught a friends wallet, he canceled all his cards and wondered what the smoke was when he filled up with gas the next day.
Personally I think the front crossover is fugly.
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:D :D :D :D
Yeah , I have a Haynes manual for BMW printed in '75 with a performance tuning section in the back . Some of it is simply incorrect ;D
Dusty
On the MZ forum, the Haynes manual is called The Book of Lies.. ;D
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The joints of the pipes in my LM2 developed cracks in several places so I decided to do without the balancer pipe in front on the alternator cover. That's to make the whole array less rigid and make access to the alternator easier. It's old Keihan Systems stainless pipes and silencers.
Since I am not going for land speed records I'm not going to dyno the motor.
Butt accelerometer says there's no difference in power after the change and I didn't notice any change in sound.
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Ace Mallot told me that on the dyno, for torque and horsepower, the hot setup was two crossovers. One that loops under the alternator and one under the transmission. That was around 2005. I did it on My Bassa that has Mike Rich dual plugged heads, Sport throttle bodies and a Norris S grind cam. I had to go to a ten spring clutch for it would slip on an eight spring unless it was fairly new. Ram clutch worked but didn’t last long enough. I don’t know how much the crossovers helped by themselves. For a reference get a copy of “ The scientific design and tuning of intake and exhaust systems “ if it’s still in print.
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It's my understanding that on 4-stroke engines a collector box increases low to mid-range torque.
Not knowing any better at the time, I switched out the Breva's 'resonance chamber' for a Mistral crossover pipe - I wanted to remove the cataliser but they are in the silencers. D'oh! Although it makes for easier oil drainage, I have noticed no difference in performance, however I hadn't done many miles before making the switch.
Just for comparison sake, my Triumph triples had 'balance' pipes on the downpipes, which equates to the alternator one on some Guzzis. Gotta be a good reason for the added cost & complication. :-) I do suspect that it smooths the pulses to the silencer(s) and hence noise output but may well be on a tangent to the actual reason(s). The gas velocity must be huge in that area and, especially at high revs any back pressure effect is surely unlikely.
(https://i.ibb.co/9m58dq8N/IMG-20230616-160655-639-2-s.jpg)
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One of the last things I did to my 850T (Norris S /X9 cam, ported heads, 36 delortos, lightened flywheel, .042 squish, bub mufflers) was the take off the stock exhaust and switch to a mistral system with two crossovers. It looks great!
My butt dyno tells me there were no gains.
A few thoughts I had
- This bike does not make enough power to take advantage of the bigger headpipes with double crossovers.
- free flow mufflers are more important than the head pipes and crossovers.