http://forum.mazda6club.com/index.php?showtopic=72510

http://forum.mazda6club.com/index.php?showtopic=71725

Those are two separate threads for two cases of blown speed 6 DISI turbo 4 engines.

and guess what, two blown engines results in two major rebuild!!! with forged internals and bigger turbo. You can only imagine their contribution to the speed6 community! It seems they've discovered some of the weak links in the engine as well.

Its amazing for a low volume car like speed6 receive so much aftermarket attention. They'll have a tuner out in a matter of weeks!, the RX-8 ECU must be a lot more advanced than the one in speed6?? probably the other way around.
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SpiceGirlXX

 

damn, what a nightmare. the fact that mazda didn't even offer to evaluate or take any interest in his rebuild is something i find rather disturbing- tho i can't say that i'm surprised. biatches that they are.

 

Yeah. I'm getting flack on the Mazda forums for challenging the notion that this new Xede tuner available for the Speed 6 adds 40-50whp with no other mods, and it safe and reliable. One guy runs a 13.18 with the Xede, as opposed to his 13.8 with just CAI and Catback he ran previously, and everyone is claiming this piggyback tuner adds 40-50whp on a bone stock Speed 6. If it does, a blown engine/turbo or another problem is the future result. I don't trust that Xede tuner as far as I can throw my Speed 6 across the parking lot.

 

Since the Speed 6 runs as rich as 9:1 afrs in certain spots stock, it's not too hard to see how they are picking up power.

 

I believe that, but 40-50whp just with an ECU mod, and nothing else? That doesn't sound safe or accurate. This exhaust is quiet, restrictive, and I can't see how that's possible. However, I have been wrong before.

 

40-50whp is definitely possible with an ECU mod on a turb'd engine. Look at some of the chips they make for the 1.8T and 2.0T VW engines. They can add from 30 to 61hp.

http://www.goapr.com/VW/products/ecu...de_mkvgti.html

 

Don't underestimate the power difference between an a/f ratio so rich that the engine is lucky it runs at all vs the proper a/f for making power. On a turbo engine, it's possible.

 

Definitely possible, but is it a likelyhood on a Speed 6 already making 270hp at 15.6psi of boost with what basically sounds and feels like a restricted luxury exhaust system? Notice I said the word safely and efficiently. Isn't the GTI detuned though with a low stock boost level, which is why it renders such great results? Is the Speed 6 really this detuned? Of course consistency is also a key as well. The Cobb Tuner for the STi consistently adds 20whp to a bone stock STI.

Hey I'm a Speed 6 owner, I'd love to be wrong here. If this is true, I'm gonna be able to have the ultimate sleeper. Just waiting for more proof, proven reliability, better tuning, and waiting for something that's plug and play. Right now there really is no evidence of this kind of gain, but perhaps there will be.


Keep in mind. I'm not challenging the POSSIBILITY. What I'm challenging on the Mazda forum is the claim that it DOES make 40-50whp safely and effiiciently, without any dyno proven results. There is a difference.

 

If it's as rich a RG is saying (9:1) then there isn't a doubt that it can make 30-50whp just off of tuning. Tuning makes a huge difference when you have that volume of air flow. Even going to a tuned rich afr (11:1) you'd see a significant power increase.

On my old eclipse a 10:1 to 12:1 AFR change netted almost 60whp (but this was on a different car and a different turbo) seen on a dyno.

Not saying everyone will get 50+whp from it but it won't be as weak as tuning AFR on a NA motor.

 

I don't doubt the capabilities. I guess I'm rubbed the wrong way by setting this in stone like, buy my product, gain 40-50whp safely and reliably with no other mods needed. I have a problem with this kind of sales approach, so forgive my cynicism, because I believe without dyno tuning, and on a product that just came out, this is currently utter hogwash IMO. He's basing his product on one guy that ran a 13.8 with a CAI and catback exhaust, and then a 13.18 by adding the Xede tuner. That's hardly proof that this system renders 40-50whp on it's own without the CAI or exhaust mod IMO, let alone doing this safely and reliably, with a properly tuned car, which is what matters to me.

However, the truth will come out, and if this is true, the Speed 6 will be a force to be reckoned with easily and efficiently, while keeping it the same quiet luxury sports sedan it currently is. I'm all for that. I guess I'm still alone on this, but I just can't help but wonder if this is exxagerating the true performance you will get from this tuner, or the truth. Thanks for all the great info. I'm learning a lot.

 

if you think 50whp from an ecu mod is nuts, go see what $1500 package will get you in a evo 9, 350whp.......

 

man that sucks, i was thinking about picking one up as well..

 

damn, that sucks the Speed6 guys are having more problems. I remember hearing a while back that Mazda had issued some kind of voluntary recall on them or something...

I'm a big fan of the Speed 6...if I ever needed a sedan, it would be near the top of my list.

 

thinking of picking up a speed 6?

don't you have an 8 and a g35? :O

hmmmm... i dunno but i don't particularly care about more speed, i just like the fun of the 8. though i do have to admit the ms6 is more "comfortable"... ie less road noise, less harsh ride.

 

Are you sure about that? This isn't JUST a turbo engine... it's also direct injection.

On that note... the guy that wants to drop his CR... that's a bad idea. THAT engine may likely not run... unless he's planning on dropping the DI. DI engines have a bit in common with their diesel brothers... they don't just run high compression because they can, they do because they need it for combustion.

I have serious reservations about the XEDE tuner and Cpe's tuner. Cpe's sound too much like a emanage piggyback and XEDE... if it wasn't enough for the 335i, then why would it be enough for the MS6/MS3? How much engineering has REALLY gone into any of them? How much testing? A few months? How much do they REALLY know about DI and possibly diesel technology? Look at how much time, testing, etc. RP and Petite are putting into their products... does anyone think that these guys are putting enough into the MS6?



MS6 recall was an ECU flash... as if there haven't been tons for the RX-8...

 

A DI engine does not have to run high compression. It isn't a diesel even though the direct injected aspect of it is similar. The advantage of DI is that you have more precise fuel control and dispersion. This allows you to be more efficient and more accurately control your flame front. By doing this it also allows you to run higher compression and leaner mixtures. This doesn't mean that you need to though. It's just an advantage.

Mazda has actually been working on DI on rotaries for years and even had one running like a diesel in that it did not need a throttlebody. That is really cool. It is only through precise fuel metering. It did not have a high compression ratio or a turbo though. Gasoline is still spark ignited. Even in DI engines. On the throttleless rotary engine, they had to add a throttlebody only because without it, as in a diesel, the exhaust temperatures were too cold to get cat light off in the necessary amount of time. By adding a throttle, they reduced efficiency and could get cat light off in the amount of time necessary. Sounds backwards to me but that's how equally backwards emissions laws are written.

The guy dropping his compression ratio is perfectly fine and probably still a good thing if he wants more boost and power. It is still a spark ignited gasoline engine so it will still be prone to detonation. It just isn't as prone as easily as a conventional injected engine.

 

I know they guy in the thread to the second link you posted- he's a local in PHX and a member of our local Arizona Mazda Owners Club.
Just after putting in his new turbo and wastegate, his wastegate got stuck closed and he hit 38 pounds of boost before he knew it, and sent a rod through the block! Wasn't his fault- he isn't crazy.
He's gonna take advantage of it and rebuild with forged internals, though, because he has the "chance" to do it now- why not?

 

Are you sure? I ask this because a very reputable source says otherwise... as in if the DI engine... particularly with turbo... was designed to run high compression... it may not burn if you drop the CR. This was in Japanese, so he could have meant it wouldn't burn completely, but either way... he didn't think it was a good idea.

If the air/fuel is less compressed, for the reason that it is less prone to detonation, isn't that the same reason it may not burn in a DI situation? That is, in DI running so much leaner... as a system, the engine is being run on the lean side. Isn't it possible that dropping the CR COULD drop the volatility/flamability of the mixutre at ignition below the threshold necessary for combustion?

Not as easily? Even at high rpm where the tming for fueling is very narrow?

Since being spark ignited means that no matter what you do in the cylinder you'll always get combustion? What about that RX-8 recall for the oil meteting problem which ultimately lead to low CR (and thus loss of power, and running very rough)?

 

A DI engine does not need to run high compression. That is a benefit of it's design but not a requirement. This is not a compression ignited engine like a diesel. Only they need high compression as that's what builds up the heat and pressure necessary for ignition. Gaoline engines do not need this. Not even DI engines. They are still spark ignited which means it doesn't take compression to ignite them. The advantage of DI is burning more of what fuel goes in. The only reason they run leaner is because you are using a higher percentage of what fuel goes in and wasting less of it. In conventional injection, some of the fuel doesn't get burned and is wasted. This shows up on an a/f gauge as being rich since it just senses the waste fuel going out. Don't think of DI as running leaner. Think of it as burning the same amount of fuel but having less waste.

If I take a gallon of fuel and bring it into a combustion chamber of an engine and only end up burning 80% of it, that leaves 20% going out the exhaust. What if I only bring in 80% of a gallon of fuel and burn 100% of it? The same amount of fuel is burned either way but this time there is no waste. This would register on an a/f gauge as a leaner burn as a result. That leaves me 20% of a gallon of fuel left over but this time rather than being waste, it's still in the tank. I'm not burning less, I'm wasting less. That in essence is how DI has an advantage. Through better flame front control you do pick up power though. A more controlled flame front means you can run higher compression without spontaneous combustion of fuel that isn't where you want it to be. You can only take this so high of course. It's all about control and wasting less. None of this has anything to do with compression ignition. Higher compression is only a side effect or benefit if you will of having better control over your fuel metering. It is not a necessity. You can have a low compression DI engine work just fine. That's because gasoline doesn't need it to ignite. That's what the spark plug is for. I think there is some confusion between DI and diesel. Even though they work in a similar manner, the fuel being used changes the rules. Diesel doesn't burn the same as gasoline.

If a DI engine is gasoline and not diesel, even in turbocharged fashion it will still follow all of the same rules of a conventional gasoline turbocharged engine. It will just do it more efficiently. It will still be prone to detonation if pushed too far. This limit will just be higher up due to better fuel metering ability. Lowering compression will have the same effect in a DI engine as it will in a conventional injection engine. It will reduce the knock tendency. This is solely because we are using gasoline as a fuel. If this were diesel fuel, all the rules of diesel engines would apply and things would work a little differently.

 

You somewhat misunderstood me. I am and have been 100% clear that DI gasoline is initiating combustion by spark ignition (thus the name DISI) and diesel by compression (and thus heat) alone. The problem has probably bee nthat I haven't been clear... and wasn't sure how to describe what I am thinking. I think I may have got it now.

As you said... DI works on fuel and timing control in order to create and control a better flame front for a more efficient combustion process. The engine was designed to do so with a controlled environment... the injectors, fuel, spark/iginition, timing, combustion chamber shape, pistion shape... and compression ratio. Changing a variable changes things... and from what I see/hear... it sounds like it's quite a tight rope walk to get these things running well... as if they are walking a fine line to achieve what they do and that changing things too much upsets this tenuous balance. Am I making any sense? Dropping the CR and possibly changing the shape of the piston head would be changing some of the variables/parameters of the combustion chamber and therefore the actual combustion cycle/process. In a sense that is obvious... one wants to lower the chance for detonation so you can up the boost, however in the case of DI where tolerances are much lower and things like high rpm injector timing much less space/time to do so... all of this for flame front control... wouldn't your actual combustion be affected beyond merely increasing the dentonation resistance?

 

I understand what your getting at Jourdan, but I think anyone's response is going to be subjective at this point (short of a Mazda Powertrain Engineer from that engine program). All engines are a delicate balance of multiple conponents and factors in a tenuous balance. Messing with any one factor will effect the others. The OEM's will almost always say any change will have a negative effect......but the tuning community has been disproving that for years.

I think this guy's project is going to be a nice test regarding the effect on that balance you mention.......whether positive or negative.

It will be interesting to see the results as that project progresses.

 

The guys that I know here say they hate working on DI and diesel... that it's a royal pain to get that balance just right for OEM applications. The overal lack of experience that both OEM's and the aftermarket relatively have with DI gasoline engines makes me cautious about the types of modifications that one can really do on these engine.

I agree... the aftermarket has been safely proving for years that the motors, etc. can safely and reliably modified and there is no reson to think that they won't be able to do DI engines too... the VW/Audi 2.0T FSI has been proving to be pretty robust.

Yeah... at this point what will and will not work is probably going to be pretty on the subjective side... part of the reason I would prefer to wait things out before going mod crazy. Unlike some people, I don't have the $$$ to spend on a new short block if I blow my engine. On the other hand... people that can, working to push the envelope does help the rest of us to know just how far things can be taken and how to do it.

This will be interesting to watch, I think.

 

Just to give a real example with real numbers on my FI RX8:

At 5,500 rpm, I went from exactly 10.0 AFR up to 10.95 AFR, whp went from 209 up to 229 whp on a dynojet with that small change..