Automatics and Dynos

lazybird4pt6

Registered User
Hey all, how's it goin'?

Got a problem and i'm wondering if anyone else has been through this before. When i'm on the rollers and I get my print out my #'s the hp and tq curves start at about 3200 RPM. This is done in third to stay in the "desired" 1:1 ratio. My peak hp and tq values are at about 3300 RPM. What's the problem? I want to see the build-up BEFORE that, say about 1500 RPM and up. When the car is being run it's in third and when you punch it the tranny jumps down to second, as it should, then shifts into third at about 3200 RPM.
The only thing I can think of to get #'s from 1500 RPM is to do the pull in second and calculate the torque difference from second to third and use those #'s.
Any ideas? Is this the only way to get what I want? The whole reason for this is to better evaluate my entire useable powerband, not just top-end. Knowing my peak #'s is good, but I need to know the bottom end as well.
Thanks.
 
If you've got one of those sctuners or tweecer or something to that effect, or even if there is a tuner present at the dyno you may be in luck.

If your transmission is electronically controlled (as opposed to just a tv linkage) you can specify a really low shift point for the 1-2 and 2-3 shifts and lower the kickdown speeds to a point where it wont downshift above say 15 mph. An example would be 1-2 at 8mph, 2-3 at 17mph and you're now in 3rd and it wont kick down at WOT unless you drop to ~15mph and stomp it again.
I'm not sure what RPMS that would put you at but 3rd gear at <20mph should be pretty low.

Just dont forget to reset that for the ride home :)
 
Thank you. No tuner, yet. I'm planning on a TwEECer RT (c'mon vacation pay - LOL!). I'm thinking that i'll be doing exactly what you described, when it's an option (4R70W tranny, no TV cable, so it's all good). Right now I don't have that option and i'm anxious to get on the dyno to test out filter/MAF/intake tube combos for bottom vs top-end and average vs peak- power/torque. I've also got a PI top end to put on next spring so i'll be doing the same thing then.
So, for NOW, will the whole "recalulate pulls in second gear" thing work?
 
Uhhh, Alan, take another look at my sig. Under my name it says what I drive (yes, they actually let me in - LOL!). I figured my username says it all, unless there's a 4.6L stroker kit for the 3.8. I'm sure that now you realize what I drive and probably don't want to know what mods i've got.:rolleyes: Ahhh, the life of the 4.6er in an SC club.;)
 
I would have assumed that have I not seen that you were an SC mechanic and very well have been working on an SC?

We only talk to people who have supercharged t-birds anyway.

:D

Wish MN12 Perf. would hurry up and get those Tweecers for us, and they better be cheaper than the SC tuners! Thing is, yours will be for EEC-V, ours will have to be EEC-IV. Doesn't yours plug into the diag. port? Pretty simple compared to our hard-wired setup.
 
Well, i'm "unofficially" the SC mech. up here 'cuz I spend a fair amount of time fixing these guys' SC's. The irony behid it all. "You have a 4.6? You know how to fix cars? You can join the club if you fix our cars." HAHAHAHA. I don't think HG's would last more than 6 months with me behind the wheel of my own SC. Besides i'm a V8 guys at heart. Born and bred.
The TwEECer will be sweet when they finally come out for you guys, especially the RT version. Don't count on them being much cheaper, if at all. The RT stuff is mondo $$$, even in US$. I still can't get over how many processors they support. They even have a unit to go with my '86 Capri with Speed-Density!
Well, back to the drawing board, er, dyno chart.

So, anyone...pulls in second, then re-calculate for third???
 
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