Accufab Plenum: 65mm vs 70mm Throttle

[todd4566]

For those of us following the plenum wars:

By now we have all seen the dyno results from mustang depot that state 70-75mm throttle bodies basically outflow the stock 65mm T-Body and produce a higher torque curve and hp ratings. Today I finally ripped off the 65mm and put on a 70mm T-body. I did this swap once before and lost a noticeable amount of low end torque, so I sold the 70. I had my fingers crossed that this plenum could better utilize a 70mm, so I bought yet another one. Unfortunately I don't have any dyno's or tracks nearby, so I did the next best thing. I slammed the gas from a roll, from a stop, and on the highway.
To make this analysis short, lets just say the 65mm wins hands down in the low end torque department. The 70mm feels much better than it did with the stock plenum, but the 65mm is still champion. I encourage all of you who have blown $$$ on these plenums to try the same experiment. Though I have not experienced the C&L, Dragon, or Trick Flow plenum, I am confident you will all notice a much better pull with the stock T-body in place. The 70mm feels good up top, but it takes longer to get up to speed.
To each his own..

 

[Beau]

i had a C & L Plenum on the stock TB for 3 weeks. as soon as i installed the accufab 75mm TB, i noticed a difference. quicker acceleration. now since it haven't had it dyno'ed i can't say for sure if i am making more power, BUT, i know that i FEEL like i am making more power.

 

[todd4566]

I wish there were a dyno down the street I could drive to right now to have this on paper. I agree the 70 has a good feel, but my car just pulls much harder using the 65. I wish this were not true. I'm tired of buying and returning these things.
Hard to say if the 70 is pulling harder up top.. it is possible but I prefer pulling hard down low much more. Makes it much easier to pass on highways and such. Keep in mind I am using the stock gear ratio.

 

[Beau]

well i still have my stock TB and i can just do some dyno runs with a stock and a 75mm TB and see what really happens. perhaps before i go out to the track in late march i'll do a little comparison.

 

[todd4566]

Well I did this test again.. I'm giving it a rest for the day; tired of wrenching and revving engines all day. Anyway, from 2000-2800 the 65 does have more go. After that, the 65 does seem to run a bit lower on steam. The 70 is obviously the opposite. Up higher it defeats the 65 (yes somewhat contradictory to my previous statement). Guess I'm going to leave the 70mm on longer and see what happens. Hopefully someone has access to a local dyno to solve this mystery. I just do not believe charts like the one attached when there is clearly some loss of torque down low w/ non-stock T-bodies. Wish that dyno started lower..