majormojo

I haven't seen a torque curve graph for the Mazda V6, but my butt-dyno tells me it doesn't have much useable torque below 3000 rpm. That's especially true when starting from a stop where the taller gearing means you have to really rev it to get a smooth start with a consistent and linear rate of acceleration. Once you're up to a reasonable cruising speed the gear ratios are better matched to the engine and there's less stirring of the stick needed for passing, hills etc. Not that the TSX really needs much shifting either, but the 6 does have a slight edge there.

TinkySD

The v6 argument is played out. You need to compare each engine on it's merrits. The tsx motor actually ha smore torque below 3000 rpms( I can provide dynos) due to some poor tuning from mazda. They both lay down nearly identical HP numbers but of course the larger displacement m6s has 10-15 more lbft though most of the midrange. The othe rthing to remember is gearing. The tsx is geared more aggresively(to take advantae of higher redline) which is going to help in the acceleration department. Don't get me wrong the m6s will be faster in a race, but not terribly so. most of their users are hiting low 15s at the tracks. The engine should be rated no higher than 205-210hp, but more like 200lbft of torque. The dyno I attached below is very middle ground. There have been numerous i've seen lower and numerous higher. From the dynos we've seen(one shows 180hp) of the tsx it should be rated more like 205/180lbft.


The major complaint of tsx owners so far is some rattles.
M6 forums have complaints about a really bad drive by wire system(multiple threads on how to fix the half second delay) check engine lights among other things.

LeeLee

The Mazda 6's HP curve is higher at most RPM points than the TSX on an aboslute value basis. However, the TSX revs to 7000RPMs, so the curve is *longer*, thus the area under the two curves is very similar.

Here I will repeat *AGAIN* the dangers of looking at crank torque, and I will illustrate the pit-fall. The Mazda6's V6 engine may have a far more impressive sounding crank torque number, but it is Wheel Torque that accelerates a car. And given the two cars have the same wheel radius, I've gone ahead and plotted the wheel torque output of both cars in 1st and 2nd gear. The TSX clearly has superior wheel torque at all RPMs, especially at low RPMs.

I repeat, cast aside all references to crank torque because it is a completely pointless number by itself.

dnb

Nicely done. Thank you.

TinkySD

that's an awesome analysis. What function do you use to get wheel torque given the gear ratios? I'd love to add that one to my bag of tricks.

One thing i'm planning on doing is switching to 22/45/17 tires which is a decrease of about 2%. I wonder if that has any disernible effect on actual wheel torque. Assuming that all mass stays the same which is sure will not.

TinkySD

are you just multiplying gear x final drive x 1:1 torque output?

LeeLee

Wheel torque is the result of crank torque multiplied by the gear ratio, then multiplied by the final drive ratio. So for the TSX in frst gear at 4000RPMs, the wheel torque is 150 * 3.267 * 4.760 = 2332.638 lb-ft

Reducing tire diameter will not change the wheel torque. However, it will change the forward thrust of the vehicle since forward thrust is equal to wheel torque divided by wheel radius. Since you have a 2% reduction in wheel radius, you will have a corresponding 2% increase in forward thrust. Thus your car will accelerate faster.

gilboman

do you have any dyno's of both cars? i think that would help a lot more.

TinkySD

I posted one earlier. I'll post them back to back. Yes the m6 has more crank torque but gearing changes what is seen at the wheels. To the best approximation me and stevtec have been able to coem up with under hard launch the m6 should be 3 tenths or so quiker than a tsx through a quartermile. From a 5mph roll they are within one car length.





Through the first three gears

mazda 6 (gear ration x final drive)
1 14.06
2 7.9023
3 5.046

tsx (advantage %)
1 15.55 (10.6%)
2 8.9 (12.7%)
3 6.45 (19.8%)

Does 3rd gear get you through the 1/4 in the tsx? Regardless what you see is the tsx has a gearing advantage which compensates for it's lower torque output. This is limited somewhat by the fact the tsx has a weak top end as compared to most of it's torque curve.(the higher gearing is giving you more amplification of the torque curve, but putting you in a weaker portion of it) That's why when the tsx gets some mods to increase top end torque you can expect significant gains in 1/4 times. So again, i'm not cliaming the tsx is faster. It's not stock for stock. But it's quite close, especially in a rolling start scenario.

TinkySD

just checked you need to just grab 4th to finisht the 1/4 in the tsx.

jcg878

Someone has probably posted this review already, but it's new to me so here it is.

http://www.topcar.co.za/pages/Featur...?FeatureID=199

I don't agree with a lot of the conclusions, both FOR and AGAINST the TSX/Accord-S.

TinkySD

remember the accord s is not the same as the tsx. Supposedly the tsx rides even stiffer. It also has a much better powerband with more bottom end and top end. + our interior is a bit more upscale.

Iceman

What I hear is, it's the best navi system on the market (would you believe that some mfrs won't let you use the navi while the car is moving??). In addition, it allows you to control many functions of the car with voice commands.

jcg878

No kidding - did you see where those weirdos put the steering wheel in that thing???

idx

Great nav system, but I seriously hope the next CD update is MUCH more up to date than the current one. I know there's always changes and there needs to be a cutoff in the data, but a hospital that's been out of business for 10 years is still listed. Another that's been there for decades isn't there.

((but yeah, all the voice commands really make it easy to use without taking your eyes off the road))


-r

rb1

Agreed, but to some extent so are gear to gear comparisons like these that use RPM instead of vehicle speed.

The TSX transmission is one of the shortest on the market, so you will have to shift 1-2 while the M6 is still in 1st, and 2-3 while the M6 can stay in 2nd, etc. I don't have the numbers in front of me, but I'd think that in every gear the M6 gets a possibly significant amount of "extra" time in the lower gear. During this time the M6 has the wheel torque advantage, not the TSX. Unless you take this into account in the discussion, this is pointless.

Redo the graphs showing vehicle speed along the X axis and then we can make a more useful comparison.

One other thing (and street dynos never show this but engine dyno's do), a typical V6 offers a substantial fraction of its torque -- like 70% or so -- even at 1000 RPM or so. No I4 comes close to doing this...