Best WOT Shift Points/RPM?

[Savage Sierra]

I have the 95 see the signature below.

I have a custom tune with modified WOT shift points. I'm having trouble getting them right in the tune. My first attempt I had the tunner set the WOT shift rpm @ 5000 rpm for both 1-2 & 2-3 shifts. With this set-up I had a slight acceleration/speed flat spot between 1-2 and a major flat spot between 2-3.

The second try I set the WOT shift rpm to 5000 rpm 1-2 & 4600 rpm 2-3. This eleminated the 2-3 flat spot but now the 1-2 is worse than before.

What I mean by flat spot is right before the up shift it just hangs there for a split second and the acceration flattens out until the shift is complete.

Has anyone figured out the best shift points on a 95 or older TBI motor with some engine mods a 4L60E w/shift improver and Corvette servo.

I know that lag is costing me .50 seconds in my 1/4 mile times.

[WhiteBrow24]

you should dyno it and see where the power curve starts to fall off and set the shift point accordingly.

unsure if thats correct, but thats what i have been told. just have yet to do it

[blown68ssrs]

What does it do when you shift it manually? An old time NHRA Pro-Stock driver Butch "The California Flash" Leal never raced with a tachometer and he had won 12 NHRA National Championship. His shifting technique was: When the car stop pulling, that the time to shift. Who cares about RPM.

[Savage Sierra]

I plan on testing that theory here in about an hour. I just don't like the darn colum shifting @ WOT, always affraid I'll hit Netural or worse reverse.

[Fast305]

I plan on testing that theory here in about an hour. I just don't like the darn colum shifting @ WOT, always affraid I'll hit Netural or worse reverse.

I would try 4,600 rpm 1-2, 4,200 rpm 2-3 and 4,200 rpm 3-4, seems to work well on every stock cam/stock head 350 TBI with bolt-ons that I have worked around.

I played aorund with Engine Analzyer Pro and you are running about 60 ft/lbs less at 5,000 rpm than 4,500 and 20 hp down at 5,000. Your peak HP is about 250 @ 4,500 with 360 ft/obs @ 3,000 rpm. The TBI 350 for all practical purposes runs the same as the GM LM1 universal 350 crate engine.

[pfk]

I would try 4,600 rpm 1-2, 4,200 rpm 2-3 and 4,200 rpm 3-4, seems to work well on every stock cam/stock head 350 TBI with bolt-ons that I have worked around.

I played aorund with Engine Analzyer Pro and you are running about 60 ft/lbs less at 5,000 rpm than 4,500 and 20 hp down at 5,000. Your peak HP is about 250 @ 4,500 with 360 ft/obs @ 3,000 rpm. The TBI 350 for all practical purposes runs the same as the GM LM1 universal 350 crate engine.

How do you go about finding your peaks without running it on a dyno?

I tried datamasters dyno, and this is what I got
I have no idea how accurate it is and therefore how much to trust it for setting shift points.


http://i188.photobucket.com/albums/z60/pfk_ca/2ndgearpull2.jpg

[Savage Sierra]

I would try 4,600 rpm 1-2, 4,200 rpm 2-3 and 4,200 rpm 3-4, seems to work well on every stock cam/stock head 350 TBI with bolt-ons that I have worked around.

I played aorund with Engine Analzyer Pro and you are running about 60 ft/lbs less at 5,000 rpm than 4,500 and 20 hp down at 5,000. Your peak HP is about 250 @ 4,500 with 360 ft/obs @ 3,000 rpm. The TBI 350 for all practical purposes runs the same as the GM LM1 universal 350 crate engine.

Hey Fast305, thanks alot thats some really good info. Can always count on you for this kind of stuff. What type of data did you put in the EAP to come up with those nembers and is that at the crank or rwhp/trq? I have the DataMaster Data with the first settings, would you be interested in looking at it?

It shows my peak HP around 4000-4100 rpm and peak torque from 3000-3600 rpm. Three differnet WOT runs.

If you want any data you can email.

[Savage Sierra]

How do you go about finding your peaks without running it on a dyno?

I tried datamasters dyno, and this is what I got
I have no idea how accurate it is and therefore how much to trust it for setting shift points.


http://i188.photobucket.com/albums/z60/pfk_ca/2ndgearpull2.jpg

pfk, I have also run the DataMaster numbers and listed them in a quote to Fast305. I know from 1/4 mile DataMaster vs Dragstrip (my post from a few weeks ago) that the TTS is pretty dang close to real world times, so in contrast the HP caculator should be as well.?

[Savage Sierra]

I would try 4,600 rpm 1-2, 4,200 rpm 2-3 and 4,200 rpm 3-4, seems to work well on every stock cam/stock head 350 TBI with bolt-ons that I have worked around.

I played aorund with Engine Analzyer Pro and you are running about 60 ft/lbs less at 5,000 rpm than 4,500 and 20 hp down at 5,000. Your peak HP is about 250 @ 4,500 with 360 ft/obs @ 3,000 rpm. The TBI 350 for all practical purposes runs the same as the GM LM1 universal 350 crate engine.

Those EAP numbers seem to be right in line with the mods I've done.
My stock numbers were 210 hp and 300 ft/lbs. so my mods gained me 40 hp and 60 ft/lbs.

Larger TBI, Headers, Cold Air kit, MSD Balster Coil etc. All basic bolt ons and the Sinister Perf. Tune.

You know I really believe if my shift points were more in my power band I think my 1/4 mile times would drop .50 seconds. I know the flat spot and lag between shifts had to slow me down. Maybe more than .50 seconds?

Probably one of the most overlooked areas of performance.

[pfk]

pfk, I have also run the DataMaster numbers and listed them in a quote to Fast305. I know from 1/4 mile DataMaster vs Dragstrip (my post from a few weeks ago) that the TTS is pretty dang close to real world times, so in contrast the HP caculator should be as well.?


From what I have gathered from most people, datamaster is "optimistic" with their dyno #'s. I think part of this is due to incorrect data being entered by the user (in this case me :D )

The weight would need to be near exact along with calculations for drag coefficient,frontal area etc. The instructions are pretty decent in the help file. I would assume that even if the numbers were not right, improvements in the numbers would still show if you are looking to see if changes were good or bad.

In my situation, I have too many read errors to trust dyno results or 1/4 mile times :( hopefully I have it tracked down to a bad cable but I will have to wait and see on that one.

Can you post exactly what you changed for your shift point data? I think I know what I want to do but I would like to see how others have changed what before I blow something up :D

[skinnyhoser]

i think he is talkin bout an automatic tranny