Originally Posted by libert69

400whp is roughly the limit the for the 5AT. during tuning and coming up on 450whp the trans developed what appeared to be a slip in the in 3rd gear towards the upper rpm range. still unknown if it was actual hard part failure or some type of electrical issue. reason being is that it only happened under full throttle. partial throttle there was no slippage.

my calculations after all was said and done suggested that the drive train loss for the auto and big power was around 25%...and that number would keep going higher the more power we made. math was based off a given psi and timing. after the 6spd swap was done and the same psi/timing was used, the power to the wheels went up big time.

the tq converter just couldnt put the power to the floor.

I have a re-stalled/built tq converter from IPT performance for sale if your interested.

If boosting your auto is the route your going then keep the power around 400 at the wheels and upgrade the tq converter with a higher stall to get you into the power band much quicker. stock stall speed is 2100 and my converter is 3000. still completely streetable and still locks up on the highway.

i could go on for days about the auto trans and big power. bottom line, keep the power below 400, new pressure switches. type F fluid is madatory (i always used amsoil super shift, same viscosity as oem and would not flare like straight redline fluid) and add a trans cooler

edit - im still a firm believer in increasing line pressure in the auto would hold more power. stock clutches never burned up and the fluid was never burnt either. figure out a way to manipulate line pressure and youll hold more power.

Originally Posted by I hate cars

I agree with Bert.

First you have to define "stronger". No one has broken a hard part that I'm aware of. The problem comes from slipping clutches.

Type F fluid and pressure switches are all we can do to help the clutches from slipping and it works well as evidenced by Bert's high mileage 5at handling 400whp very well.

I agree that added line pressure needs to happen. I've almost got it done but I stopped working on it since the IRS decided to steal from me again.

Once we get the clutches to stop slipping, and the power levels rise, it will eventually start breaking hard parts. The auto has the potential to be stronger than the manual if for no other reason than less shock due to the converter.

I agree with Bert, get a 3,000 stall converter, it will make a huge difference off the start and you likely won't fall out of vtec on the 3-4 shift assuming it's not locked.

I highly recommend if someone was going to build a high power auto and do a converter, get with one of the big time converter companies. Let them cut it open and do it right. You will get a MUCH more efficient converter meaning more power to the ground and less power being converted to heat. Also, the use of an 8" or 9" converter will make the engine rev very quickly. My usually slow revving GN revs quicker than just about any modern car because of the low weight of the torque converter. It helps acceleration and at the risk of sounding like a ricer, it sounds better when it revs very fast and drops very fast. Spend the money on the torque converter, it will pay off in several ways.

Originally Posted by thisaznboi88

get a large transmission cooler. heat will kill the clutch packs. I used this with an inline mag filter for my brother gen6 accord v6 with the glass tranney. Hasn't blown up yet. Also keep up on the fluid change.

cooler
Amazon.com: B&M 70268 SuperCooler Automatic Transmission Cooler: Automotive

filter

Amazon.com: Raybestos Inline Magnetic Automatic Transmission Filter 3/8": Automotive

Originally Posted by N1h1l1ty

Thanks azn! Definitely on my list - nice to have direct feedback on the B&M coolers, I know that was on IHC's suggestion list as well cooler wise.

I think I will get in touch with IPT this week or the following to ask if there are potential options for increasing the line pressure / upgrading the valving on the BDGA. I don't think its been done before (at least I couldn't dig anything up) but hell, I'm constantly being told that 5AT "cant do anything" - I'd like to pioneer the way if I can

Originally Posted by yungone501

Sorry Utah, LSD will not swap into a 5AT. Been down that road already...

OP, three things I swear by:

1. High performance ATF (Redline or Amsoil). Personally, I used Amsoil but a majority of the forum uses the other. The older 5AT (06 and below) will definitely benefit even more so than the newer autos (07 and up) from its ability to not be broken down like the factory fluid from the heat.

2. Fluid cooler. The cooler the fluid stays, the longer it lasts and maintains its performance benefits. Watch for pressure drops due to long/oversized lines and also coolers that are too large can be counterproductive in this sense too. Warmer climate conditions may benefit from adding a temp controlled cooling fan.

3. No throttle during shifts. This one doesn't really affect the DBW system too much because the ecu automatically closes the TB during shifts anyways but not 100%. Depending on the year and model TL you own (as well as numerous other factors that the ecu sees) the TB plate will close under shifting to protect the trans but you can improve this feature even more by momentarily releasing the pedal during shift points. This of course is easier to do when not competing with another car (and your pride at stake) but is def a smart thing to do at other times when spirited driving or joy riding. This is probably the most beneficial to those with FI.

Originally Posted by UTAH TSX

I will be watching this thread for sure, we have 2 high power automatics a 2009 TSX with over 450 WHP that has lasted 20k miles so far and the 2007 TYPE-S that is 410 WHP at 5PSI and ready to go over 500 with the new Apexi AVCR boost controller, I want to see if I can swap a manual posi diff into my auto box