MAZDASPEED 3 CAI Gains Comparison Depot

[TorqSpeed5252]

Final-drive ratio: gears 14, 3.94:1; gears 56, 3.35:1

None of these equate anywhere near 1:1. 6th gear(the closest to a 1:1 ratio) has a torque multiplier of 0.85*3.35 = 1:2.85. Meaning that the engine turns 2.85 rotations for every 1 rotation the drive wheels turn.

Since dynojet's measure drum acceleraton and engine rpm (from ignition firing), mathmatically it should compute the same horsepower regardless of gear. With one exception... That being friction. Since the higher the torque multiplier, higher the friction coefficient. The example below demonstrates the frictional losses on a turbcharged VW R32 running through its first 5 gears. 1st and 2nd gear are quite low due to turbo spool-up, but you can see my point in gears 3,4, and 5. Where each one shows progressively more power. This is due to less friction from less torque mulitiplication.

Dynojet's work based on the time it takes to move the drum (fixed known inertia), and ignition firing to determine engine RPM. From that, software determines the torque multiplication at the wheels, and converts it into nice readable graphs.

While these measurements are taken from the wheel, it is important to remember that the actual torque at the wheels is much higher than what the graph states. Since its job is to factor out the gear amplification.

Example, say a MS3 dynojet graph shows a peak torque value of 280ft/lbs while being dyno'd in 4th gear. At the wheel, the actual torque meeting the drum is roughly 1290ft/lbs. This is down converted for the graph because the computer knows how many engine rotations were made during the time it accelerated the drum to record that amount.

Then based on that corrected torque number, the simple (torque*RPM)/5252 = Horsepower formula can be applied and plotted.

I love that formula!!!

 

[Jesse MS3GT]

Red is stock.
Green has a CPE CAI(me).
Blue has a MS CAI and Turbo XS race pipe.

 

[staples187]

I must have missed something, what is the best gear to run a dyno in for these cars?

 

[camrycev6]

3rd and up.... 1st and 2nd are electronically limited...

 

[jflash]

5th

 

[Infantrylowlife]

Ok i went to the track yesterday for the first time with the CAI and i ran the same F**king times i was pissed I did like 6 passes and just wouldnt change. I Can feel a small power gain but may be resulting in wheel spin cuz i could not hook good at all i ran a 9.21 stock and 9.23 with CAI(bang)

 

[Ferdball]

Ok i went to the track yesterday for the first time with the CAI and i ran the same F**king times i was pissed I did like 6 passes and just wouldnt change. I Can feel a small power gain but may be resulting in wheel spin cuz i could not hook good at all i ran a 9.21 stock and 9.23 with CAI(bang)

Is that an 1/8 mile time?

 

[redspeed]

Do you have any air leaks? I know the cai definitely works. I got a custom cai and went from 15.52 (4k feet elev.) to 15.07 1/4 mile.

 

[bast525]

Unfortunately, I never got a baseline, but here is my dyno with the MS CAI:

250 whp/281 ftlbs.

For comparison, on this same dyno, a stock Dodge Neon SRT-4 puts down around 225 whp (no one's dynoe a stock MS there, but SRT's are very similiar in power), and a stock '05-07 Mustang GT puts down about 255-260.

So... I'd have to guess the CAI is doing something

250 whp = roughly 285 crank hp (12% drivetrain loss, conservative)... so at least 20 hp over what Mazda rated.

I'd say... best $300, warranty friendly mod ever!

 

[aciurczak]

The only reason that a gear ratio of 1:1 is recommended is that many transmissions used to have a gear that was exactly 1:1. It was often 4th gear. For that gear there would be a direct connection from the input to the output shaft within the transmission, so there was as little transmission drag/friction loss as possible.

Since none of our gear choices are exactly 1:1, the friction losses would be roughly the same no matter what gear you use. So you might as well use the highest gear possible without redlining the dyno, allowing the engine to hold the boost at its maximum for the longest time. Seems like that gear would be 5th, as long as the dyno allows the car to get to redline in 5th.

 

[laloosh]

Ok i went to the track yesterday for the first time with the CAI and i ran the same F**king times i was pissed I did like 6 passes and just wouldnt change. I Can feel a small power gain but may be resulting in wheel spin cuz i could not hook good at all i ran a 9.21 stock and 9.23 with CAI(bang)

yea im having a hard time believing these 20whp gains throughout the powerband as well. However my et went from 14.2 to a 13.9 BUT my trap speed stayed the same if not got a little lower. My best stock trap was 101.66 my best trap wiht a cai and hollowed out cat is a 100.40. in my opinion a 250whp 3300lb car should be trapping higher than 100 mph

 

[shark77]

The only reason that a gear ratio of 1:1 is recommended is that many transmissions used to have a gear that was exactly 1:1. It was often 4th gear. For that gear there would be a direct connection from the input to the output shaft within the transmission, so there was as little transmission drag/friction loss as possible.

Since none of our gear choices are exactly 1:1, the friction losses would be roughly the same no matter what gear you use. So you might as well use the highest gear possible without redlining the dyno, allowing the engine to hold the boost at its maximum for the longest time. Seems like that gear would be 5th, as long as the dyno allows the car to get to redline in 5th.

I agree 100%.

 

[dkswim]

i like mine you can feel it in second beacuse i might need to get myself a tranny mount so im not hopping soo much

 

[LENNY127]

heres a thought, or 2 maybe first off mph will always tell you added horsepower in our cars on our horsepower level 10 hp should equal about 1mph more so 20 or 30 hp should equate to 2 to 3 mph more at the end of the track, (i know that tirespin sometimes f's that up but it's a good rule of thumb), so your 1/8 mile times should be not as important as your trap speed but on the 1/8 mile on bad traction cars is even harder to catch so good luck.
second i have verified through actual runs in the 1/4 mile that my car after adding a ms cai picked up 3/10 ths consistently yet my mph changed from 98-99mph to 99 to 100mph , so my guess is 15hp is more likely to be the actual number,and furthermore I believe the cai is most beneficial in not so much total horsepower generated but it gets it done quicker , thats my eductaed guess

 

[Ben Nast]

yea im having a hard time believing these 20whp gains throughout the powerband as well. However my et went from 14.2 to a 13.9 BUT my trap speed stayed the same if not got a little lower. My best stock trap was 101.66 my best trap wiht a cai and hollowed out cat is a 100.40. in my opinion a 250whp 3300lb car should be trapping higher than 100 mph

I agreee, with 250whp 3300lb you should trap higher, but with the boost and traction limitations in first and second isnt helping things.

 

[camrycev6]

15 hp? 20 hp? 25 hp? Who cares? Every one of those is worth a $300 warranty worry-free upgrade!