Why no gains after head install?
Both the trans AND converter (slipping coupler) are now being stressed
more assuming the heads are making more power and the reduced gear
(torque multiplier) are lugging it from revving through the power band as easily
more assuming the heads are making more power and the reduced gear
(torque multiplier) are lugging it from revving through the power band as easily
Thread Starter
Joined: Sep 2005
Posts: 741
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From: North Little Rock, Ar
funny I just did that and came up with 1.25-1.35 turns to 22 ft lbs on 4 valves. According to that I am right on the bottom edge of preload and maybe my PRs are to short. So would going to a 7.35 or even a 7.375 be better?
Joined: Aug 2007
Posts: 24,241
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From: Turnin' Wrenches Infractions: 005
I think you should do exactly what that posts says. I have followed it several times and it has worked perfect. Remember, results should be repeatable from lobe to lobe.
A TC with a 3600rpm stall allows the engine to instantly jump to 3600rpm under WOT.meaning that it becomes immediately in its ideal powerband. So no matter what gearing the rearrnd has, the engine will always perform at an optimal level. Having more gearing allows the car to move easier but does not effect the motor's perforating all.
Now in a M6... the engine must progress through the rpm range to get into its ideal powerband. Having more gearing allows the engine to get to its ideal powerband quicker. Which is why an M6 with a big cam needs gears. A big cam with stock gears takes a LONG time to get into its optimum rpm range. In an manual car the gearing not only effect the ease of movment but also has a great impact on the engine's ability to perform.
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
I'm not stating this is correct in every auto drivetrain. But, with these basic setups, LS1/4l60e and a 2.73/3.23/3.73 rear being the most popular, these gear choices have little effect on ACTUAL e.t.'s and mph. Wanna prove me wrong? Do it. So far you have proven nothing.
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
From my understanding higher preload is for stock, quiet, soft lobed cams. In more high performance engines I think they do actually run less preload. But that may not apply here. Symptoms of too little preload could be worn cam lobes/lifter rollers (from the lifter jumping the lobe like a ramp) and noisy valvetrains to start.
Why don't you pull all of the pushrods and check them for straightness?
Why don't you pull all of the pushrods and check them for straightness?
Last edited by 01ssreda4; Sep 14, 2011 at 12:31 AM.
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I'm not stating this is correct in every auto drivetrain. But, with these basic setups, LS1/4l60e and a 2.73/3.23/3.73 rear being the most popular, these gear choices have little effect on ACTUAL e.t.'s and mph. Wanna prove me wrong? Do it. So far you have proven nothing.
I'm not stating this is correct in every auto drivetrain. But, with these basic setups, LS1/4l60e and a 2.73/3.23/3.73 rear being the most popular, these gear choices have little effect on ACTUAL e.t.'s and mph. Wanna prove me wrong? Do it. So far you have proven nothing.
What is your a/f at wot, peak tq timing peak hp timing? Any knock? How much did you play with timing and fuel. Did you dial in your maf properly to assure what your commanding at wot is what you are actually getting?
Gear selection does not become irrelevant in auto's.
A TC with a 3600rpm stall allows the engine to instantly jump to 3600rpm under WOT.meaning that it becomes immediately in its ideal powerband. So no matter what gearing the rearrnd has, the engine will always perform at an optimal level. Having more gearing allows the car to move easier but does not effect the motor's perforating all.
Now in a M6... the engine must progress through the rpm range to get into its ideal powerband. Having more gearing allows the engine to get to its ideal powerband quicker. Which is why an M6 with a big cam needs gears. A big cam with stock gears takes a LONG time to get into its optimum rpm range. In an manual car the gearing not only effect the ease of movment but also has a great impact on the engine's ability to perform.
A TC with a 3600rpm stall allows the engine to instantly jump to 3600rpm under WOT.meaning that it becomes immediately in its ideal powerband. So no matter what gearing the rearrnd has, the engine will always perform at an optimal level. Having more gearing allows the car to move easier but does not effect the motor's perforating all.
Now in a M6... the engine must progress through the rpm range to get into its ideal powerband. Having more gearing allows the engine to get to its ideal powerband quicker. Which is why an M6 with a big cam needs gears. A big cam with stock gears takes a LONG time to get into its optimum rpm range. In an manual car the gearing not only effect the ease of movment but also has a great impact on the engine's ability to perform.
The explanations as to why rear gears don't matter in automatics that I have read so far focus on: (a) what the stall does for you on the starting line; and (b) the slippage that occurs throughout the run. Since the ability to spool up the motor on the starting line is common to both automatics (using the stall feature) and M6s (using clutch and/or tire slippage) I don't see anything that would render the rear gear selection irrelevant. Regarding the slippage thing, it seems to me that "all else equal" an automatic would slip more against a taller rear gear (e.g. 3.23) and conversely slip less against a lower rear gear (e.g. 3.73).
So, I am thinking there must be some other factor particular to automatics that mitigates the effect of rear gear ratios.
In my M6 (T-56 close ratio), the "engine must progress through the rpm range to get into its ideal powerband" only once - in low gear. Even then, the period of progression can be very short due to clutch and/or tire slippage. After running low gear is to redline (6.5k rpm) the shift to 2nd gear, and every shift thereafter, I arrive in the next gear at 4.5k rpm. Since the torque peak on my motor occurs at 4.8k and peak horesepower occurs at the 6.5k redline the motor is never out of its power b