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Zard Cross exhaust numbers

10K views 37 replies 5 participants last post by  casida 
#1 · (Edited)
Zard Cross exhaust numbers?

I haven't been able to find any dyno charts or hp/tq figures for the Zard Cross 2:1 for the Scrambler (the short one). Before I drop 1k on this exhaust, I'd really like to know what I'm getting. Anybody have anything? Also, what map are you using?

Alternatively, how hard is it to fit Thruxton pipes to a Scrambler, and what kind of remapping would be needed?

Thanks.
 
#2 ·
Good question, I'm also interested in the Cross. Hopefully someone in the know will chime in.

I'm running Thunderbike exhaust, and recently ceramic coated the heat shields, but I'm still a little disappointed in the visual prominence of the high pipes. The Zard Cross looks awesome on a scrambler, but it needs to compare in performance if I'm going to spend that money, and lose the center stand...
 
#3 ·
I'll have one for you on Wednesday of next week. I don't care what it puts out for power right now, though, because it's not tuned super-well yet, but the week after that, I should be able to post mine with my custom map that I'll have written for it.

The 2:1 makes a big difference in weight, mostly. Power-wise, I'd be surprised if it were much different than any other 2:1. But the gains will be at the higher revs, not really the lower, where the scavenging aids the exhaust flow.

I'm also running without an airbox, so that should be a consideration when looking at my dyno graphs, too.
 
#5 ·
OH! Sorry, yes.

Without some serious tuning, the Zard will lose you some serious area under the curve. The Cross causes the bike to run substantially leaner than the Arrow 2-1. Now, that said, now that I'm dialing in the tune a little closer to correct, the thing is picking up a pretty serious amount of power step-by-step. The biggest area was the middle RPM at high throttle was lean as a soy burger on a diet (think 17-18:1 at worst.)

What I find most notable is even with the power loss, the bike was faster with the Zard due to the removal of so much weight. =)

This problem will likely be much less pronounced if you have the stock airbox, but I don't.

Peak HP/torque numbers were pretty much that of stock, however.

One more week and I'll have my NEXT tune dynoed! Lather, rinse, repeat. I figure another two or three sessions will probably have the bike exactly where I want. The thing already screams like a rocket by comparison to pre-dyno performance, though. =P
 
#6 ·
Thanks for the feedback.


But oi, that's bad news... So even the Arrow 2:1 map is too lean? Where could I get a map for the Zard then? Not planning on removing the airbox either.

$1k just to return stock hp/tq figures... hmmm.


Btw have you been paying attention to your mpg? Has the Zard significantly worsened your fuel economy?
 
#7 ·
Yep, the Arrow 2:1 was leaner than my first map, and mine was still way too lean. You'll need to custom-make one until Pieman comes up with a set, or you could try running my map, though it'll be designed for no-AI, no-O2 sensors, no airbox (open element filters) and the Zard Cross.

My MPG hasn't really gotten worse or better; I've always gotten between 40-45, and I usually wring the heck out of the bike. On the few circumstances where I'm riding gently, I'll get in the low 50's on longer rides. I'm going to be paying more attention as I adjust the fueling even more. As it is, on the ride in I didn't crack the throttle open nearly as much as I did before with the new map, suggesting I'm closing to my goal.

I'm betting there's a lot of power to be had with the exhaust, but it sure is going to take a goodly amount of tuning to get there. So, is it worth it for anyone else? Probably not at all. But for me? Yeah. I'm a tinkerer, and I've done crazier things, ECU-wise, than this. =)

My maps will be freely available, in either case. Hopefully next dyno will look prettier, with higher numbers. I'll post a scan of the first one (as embarrassed as I am by it!) when I get home.
 
#8 ·
Thanks. How much of a difference do you think your other modifications made (airbox removal, AI removal, O2 removal) when it comes to how lean the mixture was? I'm not planning on doing any of that, so do you think the Arrow 2:1 map might be fine for my purposes?

Any word on when Pieman will come out with Scrambler maps?
 
#10 · (Edited)
Howdy,
I bought my 2010 EFI Scrambler used, it had the Arrow 2 into 1 exhaust, a stock airbox and filter with the "flash" from Triumph for the EFI.
It was putting out 50.04 HP & 46.33 ft/lb (rear wheel) with this set-up

Then I installed my Zard cross, K&N , NH bellmouth, airbox baffle removed and PC-V with custom map. Also, I removed my AI system and O2 sensors.

Now it's putting out 55.34 HP & 51.05 ft/lb to the rear wheel.

If I had done a little more research, I probably would have gone with a DNA filter and PieMan's Breathe "bellmouth".

I am quite happy with my results, though.
 
#11 ·
The airbox removal will definitely be the biggest culprit for the lean-ness. Even still, I was quite shocked at how lean it was after dialing up the fueling as much as I did.

Stock, the Scrambler will put down 40-45 on a Mustang dyno, that I've seen. Just anecdotal, but that's been my experience.

If I were suggesting it to others, TT RDHS' direction would have been the way to go. The modern airboxes aren't THAT bad, frankly, and once you've removed the baffle and popped in a UNI/K&N with a bellmouth, you're pretty much going to be up where I'm going to be for power once the fueling issue is resolved. I think I'd go with the stock ECU rather than using a piggyback like the PC-V, but that's just personal preference.

I estimate in the 58-60hp range for my little beasty once all is said and done, but I might rethink my pod filter configuration. We'll see what the dyno says about the newer velocity stacks shortly. I'm hopeful, now that the fuel is feeling a lot better overall after two or three tuning iterations.
 
#13 · (Edited)
Neat, I'm doing much better this time at the dyno. 54hp/47ft-lbs with a nicer, flatter A/F that doesn't go all the way between 18.7 and 13:1. A little too rich now, however. =P

The guy at the dyno was impressed with my results after just one session. He figures (as do I) that I've still got around 8-10 more horsepower available in getting the tuning just right for my velocity stack setup and just little fiddlings.

With this last map I JUST installed, I was riding around and all the tiny flat spots seemed to be gone, and it pulled angrily to about 110mph without any qualms, at which point I eased back. Feels like I picked up a bundle on the top end, as this morning it was a bit more hesitant.

Those bumps and valleys you see on the AFR are likely smoothed out to next to nothing by now. Wheeee!

Edit: Attached the dyno results. Sorry about the crease!
 

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#17 ·
Mmmm, yeah, probably would void your warranty. =) And that map was less rich than the map I started with, so you'd pretty surely be in the extremely lean range. Probably in the 15-16:1 range if you still had the stock airbox, I figure, just based on dead reckoning.

- Eddie
 
#21 ·
For those who are curious, I'll post my zipped-up map here, too. I'll revise this probably 2-3 more times, but this should work as a baseline for those who have 2-1 exhausts and have deleted AI, O2 sensors, and open filter bodies.

This is specifically for the 2009-10 US Triumph Scrambler, running 91 octane (crazy advanced timing compared to stock) and up to E10 fuel. This model is the one that had the mechanical odo and cable driven speedo.

I can port this to another person's mapping, too, as long as you have the 270 twin. At least I'm pretty sure there's no intrinsic difference for the newer models. =) I'll double check the maps online, though, 'cause I'm curious.
 

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#22 ·
By the way, the tune above was designed for with the DB killer baffle in, and the dyno reflects that being installed. I've got about half of the tune done with the DB killer out, which has easily picked up a few more horsies. There's a dyno day tomorrow to see what all I picked up, but I won't get scans for that one, since they're just doing a fun event. =) I'll let you know what, if anything, I find out, though!
 
#23 ·
My HP/TQ numbers are with the DB killer OUT.
At idle, it's one of the nicest sounding bikes ever. And when you wick it up, it sounds amazing, but just too loud (for me & my neighbors).

I put the DB killer back in, but it sounded like crap, and had a weird high pitched whistling sound.
I removed the bar on the inside of the DB killer, and cut about an 1.5" off it. Now it sounds nice, and not too loud. (And the high pitched whistle sound is gone.)

I have not put it back on the dyno with these changes, but the bike feels great.
 
#24 · (Edited)
62.6hp and 51.2lb/ft with the latest tune, with some little adjustments to the velocity stacks and high RPM maps. Feels like the correction for the AIT sensor is off a wee bit, so I'm going to play with the location of that. Might be getting a leeeetle too warm where it's sitting in the air stream, but we'll see what fruit, if any, that bears! Might also play with the map sensor corrections a little more, depending on how the next few long rides goes.
 
#25 · (Edited)
So theoretical situation:

I order a Zard Cross to put on my Scrambler. I don't want to remove AI or O2 sensors. Casida says the Arrow 2:1 map is too lean if you open up the airbox for more airflow. With the stock airbox and intake, will an Arrow 2:1 map and a Zard Cross be fine? I actually wrote an email to Zard (in Italian, I used Google translate) asking which map should be used with the Zard Cross, and they said an Arrow 2:1. I'm guessing they assume that the rest of the motorcycle will be left stock. Will I even see an improvement in horsepower and torque if I leave the airbox stock, or will I be just wasting money and fuel on the Zard Cross unless I improve airflow through the airbox? A freer-flowing exhaust requires more airflow, or else it's wasted, no?

Squeezing every last bit of power out of the bike is not important to me, as I use it to commute and travel, but if I'm not going to get any improvement from installing the Zard exhaust unless I modify the airbox, I might as well save the money and keep searching for a complete Bonneville exhaust system. I need a low exhaust primarily to facilitate hard luggage.
 
#26 ·
Mmm, you'll feel a difference to be sure. Even if just from excising over twenty pounds from the butt of the bike. The AI is going to cause lots of popping, and you'll probably have a lot of low-speed snatchiness if you stick to using the O2 sensors, but if you don't mind that so much, you can do some adaptation to allow it to work a little more smoothly. You should also make sure your throttle bodies are balanced, because having these unbalanced throttle bodies is made REALLY obvious by that map. REALLY obvious.

I don't like poo-pooing on the stock maps all that much, but I really don't like the stock setup for the Arrow 2-1 for the scrambler. It seems like they threw it together hastily and didn't refine it very well. That, plus the O2 and MAP corrections are laughably unsuited to low-speed riding on that map, as they seem to be more-or-less stock numbers, with the flat (open-loop) maps dialed in a bit better.
 
#27 ·
This is my first bike with EFI, so I'm ignorant in these matters, but what's the point of deleting the O2 sensors? Don't they automatically adjust fueling depending on air density? Wouldn't deleting them kind of negate the whole point of EFI, which is automatic adjustment to temperature and elevation?

Also, wouldn't removing the AI trick the bike into thinking that it's running too rich, therefore making the computer lean it out even further?


So far, with stock everything, I haven't observed any of this snatchiness at low speed that people talk about.
 
#28 · (Edited)
Ahhh, well... Here's where things are kinda weird. =) Some vehicles use the O2 sensors very heavily, but this motorcycle wouldn't be one of them. Most vehicles operate in two modes:

Closed Loop - This is where the vehicle operates by consulting the O2 sensors by using the O2 sensors to close the circuit of consultation. The O2 sensor's measurement is consulted, and the fueling is adjusted accordingly in an attempt to meet the particular O2 level prescribed in the O2 map, generally somewhere between 12:1 to 14.7:1. Since the sampling rate is very fast, the adjustments can happen rather quickly, but generally not fast enough to accommodate quick throttle transition or high RPM operations. That is where the next mode of operation kicks in...

Open Loop - Open loop does NOT consult the O2 sensors to make adjustments. Rather, it takes (in simplified terms) a) Throttle Position, b) Manifold Pressure (MAP), and c) RPM. With this 3-dimensional matrix, it adjusts the level of fueling, metering the amount of fuel by keeping the injectors open for longer or shorter amounts of time to allow more or less fuel to enter the system. This way, reaction time of the O2 sensor is a non-issue. This situation (open loop) happens when there is a rapid transition of throttle, or when the throttle position reads above 70% (roughly,) or when the RPMs exceed 3800. So, needless to say, a lot of the time, you're operating in this state.

So, when disabling the O2 sensors, you make the ECU aware of the fact that you ONLY want it to consult the TPS, RPM and MAP sensor rather than looping in the O2. The variance in the maps mean that there's a chance you'd drop from a state where the ECU was sitting at a rich 12.7:1 then tries to transition to a near-stoichiometric 14:1. This sudden switch of behavior is what causes the 'snatch' a lot of of people feel on both decel and decel-to-accel transition. This is very much exacerbated when you have a freer-flowing exhaust or intake due to the fact that the environment that the O2 sensors measure, the exhaust stream, can shift to an extremely lean condition very quickly compared to the turbulent, restrictive environment of the stock plumbing.

The system's 'adaptation' allows the adjustment of various levels of this map to a value of UP TO +/-10% of it's prescribed fueling at certain RPM, which makes it better suit the unique operating environment of your bike. But, this may not be enough adjustment in some cases, and it makes your map more unpredictable, since your adjustments will be adjusted around for the lower RPM/lower throttle position regardless of any changes you may make. This unpredictability is what a lot of tuners dislike, since every time you make a change, the bike will try and adjust around it to keep the results the same or similar to it's target O2 range.

Now, onto your question about air injection. Air injection does exactly what it sounds like; It takes air from the intake tract, opens a large metallic valve that allows that air to be drawn into an air passage that is connect to the exhaust side housing. This air that gets drawn (or injected if you will) into the exhaust acts like a reverse EGR system on a car. The air leans out the mixture, causing it to burn or ignite in the exhaust system. This means much lower levels of unburned fuel in the air, but instead of that, you get higher volumes of CO2 and NOX emissions. It's a bit strange and counter intuitive, but when you realize that advanced ignition causes more 'complete' burn at the cost of increasing NOX emissions, it makes sense. So, in light of wanting lower airborne particulates, we mildly adjust the level of air in the exhaust. The ignition happens, typically, at the hot part of the exhaust and after the point where turbulence doesn't prevent ignition. It's usually downstream from the O2 sensors a lot, so this change isn't measured or accommodated for by the map in any measurable way. The AI just 'functions', it doesn't consult the sensors in any meaningful way to adjust it's own behavior. It's a valve that is either open (decel, mid to low rpm) or closed (all other times.)

The air injection can, therefor, cause excess ignition in the exhaust itself, and cause reversion when this ignition happens, where the exhaust flow suddenly reduces it's laminar flow by the rather sudden introduction of a pulse wave that expands in both directions as a side effect of the ignition downstream in the exhaust.

Phew. So, what do you lose by shifting to O2-less operation, to step back? The adjustment is still cogent of the ATS (Air Temp Sensor, in the intake tract) and it knows about changes in elevation via the MAP (Manifold Absolute Pressure) changes that take place when your air density is lower, due to the fact that the air pressure would drop at higher elevation. You do lose a degree of the ability to run leaner mixtures on deceleration and low throttle input states in a safe manner, but this can be tuned into the map directly if it's the behavior you prefer.

I hope this makes it a little easier to understand the O2 sensor thing! Sorry for how wordy I was. =)
 
#29 ·
Wow, thanks. It's starting to make sense. I'm assuming that eliminating the O2 sensors will result in a noticeable drop in fuel economy, since the mixture won't be as lean at steady throttle or low speeds anymore? Again, I'm not racing this bike, so given the choice between 1 hp and 3 mpg, I'd take the mpg.

Would eliminating the O2 sensors even be necessary if I run the Zard pipe but keep the airbox stock? Since the Zard pipe for EFI bikes comes with O2 sensor ports, I'm assuming that Zard intends the pipe to work fine with stock airbox and O2 sensors? Would the increased amount of fuel needed for the Zard be within the O2 sensors' adjustment capability of +/- 10%?
 
#30 ·
So, your very thoughts were my concern with eliminating the O2 sensors. The madness of this? It seems as though removing them has no real effect on the fuel economy of the bike in my experience. Your milage may vary (hahaha, see what I did there?)

I'm not racing mine either, so there's your practicality measurement. =) It wouldn't be necessary at all with the stock airbox, but any map tuning you do will be made more difficult to dial in by the active adjustments made around the O2 sensor readings.
 
#31 ·
OK with the dropping temperatures I've started noticing this stumbling and hesitation you're talking about. In 5th gear at around 3,500 RPM (about 62 mph or so), if I roll on the throttle, there is a definite hesitation. The bike also seems to "hunt" for correct fueling at slight throttle openings sometimes. By no means is this severe, although I can see it becoming annoying pretty quickly, and especially if it gets worse as the temperatures drop even further.

Will the Zard pipe, an Arrow map, and stock airbox eliminate this?
 
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