This has been discussed already at length and is a VERY STUPID idea!!

You just spent $30k+ on a car and you are willing to risk the car to save $15 on a dyno. If the AWD doesn't disengage, you will go into a wall

 

If the AWD doesn't disengage, you will go into a wall
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Hopefully they would have strapped the car down on both ends so this won't happen - probably just end up stalling the engine.

 

This has been discussed already at length and is a VERY STUPID idea!!

You just spent $30k+ on a car and you are willing to risk the car to save $15 on a dyno. If the AWD doesn't disengage, you will go into a wall
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Not if you jack up the rear end and secure it in a safe manner. They would absolutely not go into a wall if they have it properly secured. I would never let a place dyno my car unless they do it right anyway, even if it was free. Plus they're supposed to start at low revs anyway. If it starts to roll forward what kind of morran would keep giving it gas while they were in it? If anything, it would roll over the roller and they would stop, plain and simple. You shouldn't shoot somebody down and call them stupid because YOU wouldn't take their suggestion. This could be a good thing. How do you think the evo guys found out they could remove a chip and BAM it's a rear wheel drive evo ready to do burnouts and even drift. I say go for it dude. Don't let anyone discourage you from experimenting. It's people like that who are the reason we don't have alot of support in the aftermarket.

 

This has been discussed already at length and is a VERY STUPID idea!!

You just spent $30k+ on a car and you are willing to risk the car to save $15 on a dyno. If the AWD doesn't disengage, you will go into a wall
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You obviously didn't read the post, so spare me the rant, bubba. Consider changing your title to "overeager noob flamer".

I said I cancelled the dyno and realized it would be unwise to try this on a 2-roller dyno given that the AWD CM might change it's mind. My question was really whether it might be theoretically possible to get a front wheel only dyno on a 4-roller dyno. Sorry if my not specifically mentioning the 4-roller dyno caused you to pop a blood vessel or something. My idea is that we might get some idea of the power lost through AWD tranfer to the rear wheels. Again, all performed on a 4-roller dyno.

And, oh yeah, now I vaguely remember a thread about this that ran about four months ago, but I don't remember what the conclusion was if any.

 

It should also be noted...that a 2 wheel dyno (if you beat the AWD system), would dyno higher then if all 4 rollers were moving. ie you'd get a result that wasn't indicative of your actual drivetrain losses.

 

It should also be noted...that a 2 wheel dyno (if you beat the AWD system), would dyno higher then if all 4 rollers were moving. ie you'd get a result that wasn't indicative of your actual drivetrain losses.
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Right! And the difference between the two dynos (one with FWD only, one with AWD, again all done on a 4-wheel dyno) would show the drivetrain loss due to AWD. That was my point. Sorry it was so obscure. I may actually try it.

 

For one, you're presuming that the PCM makes no changes to the engine at all when it turns off AWD when you pull the hand-brake. I don't know if I'd take that bet myself.

Secondly, dyno variance would be killer. You'd need a lot of runs in each 'mode' to get a decent idea of the difference since you'd be compounding your drivetrain variation with dyno variation. Even that would be questionable because there's no guarantee that the dyno is just as accurate in 4-wheel mode as in 2-wheel mode. I would be willing to be that it's not. It very likely consistently measures one differently than the other, slightly higher or slightly lower. Dynos aren't as cut and dry as most would like them to be. There's a LOT of corrective factors going into that. If I were going to do your experiment and was more curious about the difference in power rather than the actual power itself, I'd have the dyno operator turn off all corrective factors. I think that would yield a more reliable comparison between 2- and 4-wheel runs.

And lastly, is the AWD even engaging in dyno runs at all anyway? Since dynos are done from a roll, and there's no wheel slip at all allowed, why is the AWD system engaging? Is it because the front wheels are spinning and the rears or not so the car thinks you're stuck?

 

If someone really wnats to try this on their MS6 please get it on video so the rest of the people on here can laugh at you being dumb..

You bought an AWD car...use an AWD dyno, you might as well unhook your turbo and dyno it then too since youre not looking for an accurate dyno reading

 

If someone really wnats to try this on their MS6 please get it on video so the rest of the people on here can laugh at you being dumb..

You bought an AWD car...use an AWD dyno, you might as well unhook your turbo and dyno it then too since youre not looking for an accurate dyno reading
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Dude! Get a grip! The whole point of this is that MORE POWER WILL BE GETTING TO THE WHEELS!!!!!!!!!!! I really am curious as to how much. Our AWD brings the hp down to around 215-220 by the time it gets to the ground. With a temporary FWD set up, we could be seeing around 250+ at the wheels. I would take that over an AWD launch that appearently will shatter the diff according to another thread on here. Let him try it. Either it will work, and shut up the nay-saying sissies that are still stuck on how much they paid for the car, or it won't and it'll pull the tie-down straps tight and maybe roll forward an inch or two. The dyno operators will know if its working or not the very instant they put a shread of weight on the gas pedal. Do you really think they would keep pushing the gas after it shrugs?

It's called "common sense" and is quite useful if it is used properly.

 

1> I'd take a 215whp AWD launch anyday over a 250whp FWD launch if acceleration was my ultimate goal.

2> The worry is not that the AWD would engage "with a shread of weight on the gas pedal". The worry, and the reason why no dyno operator worth a damn would try it, is that the AWD system would engage when the front wheels slipped at, say, 4000rpm, instantly sending a significant amount of power to the rear wheels. From a slow start the AWD system isn't engaged anyhow. Is it likely to kill someone? No. But any dyno operator willing to take my word that my hackjob on the e-brake is going to keep my rear wheels from spinning isn't a dyno operator I want when my car is on the rack.

3> It'd be pointless to try this out on a 2WD dyno anyhow. You can't dyno your car on one 2WD dyno then drive across town to a 4WD dyno and try to compare runs. You would need a 4WD dyno and just try it out there. On one test you're using all 4 rollers and on the other you're (hopefully) just using 2, and you've still got the 2 back there in case your system engages. You get to see if it works, you get the safety in case it doesn't, and you actually get readings that are comparable since you're at least using the same dyno.

 

If someone really wnats to try this on their MS6 please get it on video so the rest of the people on here can laugh at you being dumb..

You bought an AWD car...use an AWD dyno, you might as well unhook your turbo and dyno it then too since youre not looking for an accurate dyno reading
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Um, what do you think is going to happen on a 4-roller dyno? It's not going to jump off a 4-roller just cause the rear wheels start spinning unexpectedly. I already said twice it would be dumb on a 2-roller dyno. Again, the only point is to try to gauge how much power is lost in transmitting power to the rear wheels given our AWD system.

Sigma, I take your points. But are you saying there a potential for harm on a 4-roller?

 

Nah, on a 4WD dyno you should be fine.

The dyno will freak out if/when your system engages and the run will be worthless, but that's all that should happen.

If on a 4WD dyno they lock the rear drums when testing a 2WD car, and I can't remember if they do or not, then you should tell the dyno operator to unlock them if he can, just in case.

I would be very upfront with the dyno operator on what you're doing and give them the opportunity to back out if they want. It's their machine and their liability insurance and they should ultimately be the ones to give the go-ahead. On a 4WD dyno I can' t imagine why they wouldn't.

 

Nah, on a 4WD dyno you should be fine.

The dyno will freak out if/when your system engages and the run will be worthless, but that's all that should happen.

If on a 4WD dyno they lock the rear drums when testing a 2WD car, and I can't remember if they do or not, then you should tell the dyno operator to unlock them if he can, just in case.

I would be very upfront with the dyno operator on what you're doing and give them the opportunity to back out if they want. It's their machine and their liability insurance and they should ultimately be the ones to give the go-ahead. On a 4WD dyno I can' t imagine why they wouldn't.
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Thanks, worth a call ahead to see it's a definitely a waste of time or just maybe a waste of time. Frankly, I was just looking for some angle to make it worthwhile to do a dyno even though I don't have any mods planned at this point.

 

Dude! Get a grip! The whole point of this is that MORE POWER WILL BE GETTING TO THE WHEELS!!!!!!!!!!! I really am curious as to how much. Our AWD brings the hp down to around 215-220 by the time it gets to the ground. With a temporary FWD set up, we could be seeing around 250+ at the wheels. I would take that over an AWD launch that appearently will shatter the diff according to another thread on here. Let him try it. Either it will work, and shut up the nay-saying sissies that are still stuck on how much they paid for the car, or it won't and it'll pull the tie-down straps tight and maybe roll forward an inch or two. The dyno operators will know if its working or not the very instant they put a shread of weight on the gas pedal. Do you really think they would keep pushing the gas after it shrugs?

It's called "common sense" and is quite useful if it is used properly.
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What the hell would it matter if your "FWD" setup is putting 250 hp to the wheels if the AWD does 215? Do you want to drive your car around town in only FWD? If having the most hp is your goal then why buy the MS6 in the first place?

Well if you want the most power getting to your wheels get under your car, unhook the rear drive coupling and take out the diff and drive shafts in the back then get your dyno done.

 

Do you want to drive your car around town in only FWD? [/b]

That is exactly what the car does. It's FWD that seemlessly integrates into AWD. I bet for 99.5% of everyone's driving that isn't from a standstill, you're in FWD mode. That "is" the whole point of this AWD system.

Less drivetrain loss = more power and greater efficency (more mpg). Basically you end up "theoretically" with the best of both worlds. AWD when you need it, and the extra power and fuel efficency of a FWD system. (Of course you still have to haul all that excess weight around)

 

My point is if you want to test your car's performance why subject it to conditions that aren't condusive to normal operation.

 

Okay, I'm pretty sure it works. I pulled the ebrake while driving and let it sit on lowest notch, DSC off. Came to a stop on a slight uphill grade. Did a 3500 RPM takeoff and the wheels spun nicely. Stopped up the road a little ebrake off, DSC back on, and another 3500 RPM takeoff. No spin, just a chirp and off I went. Now to try driving through some fast corners to see if I can notice the FWD understeer vs. AWD tightening up the corners.

Also, for the 40th time, my only point is to try and get an estimate of the drivetrain powerloss that our AWD system has in sending power to the rear. If may be very little, it may be substantial. But I don't think the car will perform better or get more useable power to the ground in FWD mode. To the contrary, I think the AWD is pretty awesome. However, I am curious to see how much difference I can tell. Just me, personally, so it needs not have implications for anybody else. This is just a matter of curiousity and a way for me to add a twist to getting a dyno. I don't have any mods in the work and therefore don't need a baseline. Plenty of other stock MS6's have had dynos done, so just getting an AWD dyno won't add much to the knowledge we have already. Like I said, just curious!

 

Okay, I'm pretty sure it works. I pulled the ebrake while driving and let it sit on lowest notch, DSC off. Came to a stop on a slight uphill grade. Did a 3500 RPM takeoff and the wheels spun nicely. Stopped up the road a little ebrake off, DSC back on, and another 3500 RPM takeoff. No spin, just a chirp and off I went. Now to try driving through some fast corners to see if I can notice the FWD understeer vs. AWD tightening up the corners.

Also, for the 40th time, my only point is to try and get an estimate of the drivetrain powerloss that our AWD system has in sending power to the rear. . . .
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Well, finally got a chance to do some aggressive cornering with AWD and DSC off. Steering felt heavier and fast cornering was much less confidence-inspiring due, I think, to having to compensate for more understeer. I don't know how much is due to AWD and how much DSC, but the corners are much tighter when they are on. A lot of you are probably saying "Duh", but you never know until you try. Next, I'll cornering without the DSC and see if that makes a noticeable difference for me.

I definitely won't swap my MS6 for an MS3 without a serious test drive. Even for such a big bump up in hp/lbs. On the positive side, torque steer was not somewhat noticeable,but not that much of problem, which may bode well for the MS3.

 

plus burnouts are fun.

 

plus burnouts are fun.
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FWD burnouts are not fun...RWD are a different story