Speeds at shift pointw

[LancePearson]

I'm getting used to the power and have a couple places where I can safely run it occasionally with the pedal all the way down. As you are going pretty fast I don't watch the tach a whole lot preferring to focus on the road for safety but it seems to me like my ear and the few brief glances at the tach I have snuck tells me I shift out of first somewhere in the fifties and I have shifted out of second I believe once at 79 and once yesterday at 92 then into third and start running out of road so put it into fourth then lift off about then already being somewhere north of the century mark.

Stock engine as far as I know but what is your experience with yours shifting when you are pushing the car fast from a stop or slow speed to max acceleration? How fast are you going at your shift points?

I think there is a lot of overlap and decision to make as sometimes it might be better to shift earlier into third than maxing second at some level of rpm versus mph and same for third and fourth which I call "long" gear ranges and fifth is a very long gear range. The power seems able to handle any combo I want that way.

Thanks in advance if you even think of it this way.

lance p.

[Kevin]

from memory the top of third is around 120

[Pete]

If you have stock rear gears,your short shifting.

1st to 58-60
2nd to 88-90
3rd to 119-121
4th to 149-151
5th to 175-180
6th to the moon

These are withen 1-2 MPH depending on what rpm you hit each gear.

I hit 129+ in 3rd @ 7500 in the 1/4 with stock 3.45 gears.

Enjoy Safely
Pete

[Paul Workman]

Just to add...

Tach hysteresis (aka "lag"):

A shift light will relieve you from glancing at the tack - which is lagging rpm anyway -, AND optimize your shift points. Several of us like the Raptor light because it is easy to set, and it can be easily hidden in the A/C grille. Far as fine tuning the shift point itself goes, some "test and tune" is involved to get it "right".

Note: In the photo, not all 7(?) of the LEDs are illuminated as they normally would be when the rpm trigger reached the preset point. At initial power up (as seen in the photo) the lights are sequentially illuminated as part of an initial self-check routine, saying - "Hello! I'm awake and ready!" before going dark. But, recessed as the light is, back in the dark of the grille, there is NO PROBLEM seeing the signal, even in sunlight.

Raptor link

P.

[Fully Vetted]

You gotta remember, Lance...these LT5's love to rev. Pete can elaborate more about the torque curve but the "sweet spot" on these things seems to be right around 7000 RPM and they absolutely never lay down.

[LancePearson]

Thanks all. Very helpful information. The Raptor does look interesting if I were going to take the car to the drag strip.

I had not thought of the lag of the tach but that is so logical with as fast as this engine revs and the idea that it never lays down is true based on my own brief experience, absolutely the truth. Mine just keeps pulling and I swear, the longer the gear the faster it seems to rocket me and the body down the highway. It almost takes your breath away and takes a little experience so I can understand and be used to the sensations which I'm getting.

I took my 76 to a road course and ran it in four 25 minute sessions in May, 2011 for the experience and had never been on a track much less VIR's 3.27 mile 17 turn, 2 kink course. It took me probably five laps before I was comfortable letting it fully out especially on the straight after the oak tree turn which rises up a blind hill into an eventual turn and some more turns down into what the track calls "hog pen." At first it was all intimidating and I went much slower but after the second session and riding with a pro driver a few laps in his car then I got back in and it made more sense, I was used to it and then my lap times dropped a minute plus each 25 minute on track session. So, that's how I experience new things and this LT5 engine is a new thing and a half.

I have a TBSS 2008 with 4:10 rear end and LS2 ~~ 410 hp engine in it which is really quick for a road race prepped suv built for road racing by GM performance group but it can't hold a candle to what this little 1991 with the LT5 can do. Not even close. The weight at speeds under 100 mph is countered by the 4:10 rear end versus 3:45 rear end in the ZR-1 so that somewhat equates it. The TBSS leaves everything around it on the highway very quickly but just does not have the punch and pull of the LT5. Sorry, GM, but I do have a sort of direct comparison in my driveway.

It's why I bought the Z, I got used to the punch of around 400 hp.

Absolutely delighted with the 1991.

Thanks again, guys.

Lance Pearson

[Bob Eyres]

Go ahead Lance, nail it in the first three gears to get the feel of where that rev limiter comes in, that's what it's for. These motors are at their best up there near 7K.
My 91' with 4.10's tops out in 4th in the low 120 mph. range. feels gooood.

[dredgeguy]

Lance,
Took mine to the track this summer after owning it for 2 months. Have stock gears and went through the quarter mile in third at 116 mph at/around 7000 rpm.
Going to look into the Raptor for next summer.
Looking forward to meeting you during the next WAZOO get together.

[Paul Workman]

Originally Posted by dredgeguy

*snip* went through the quarter mile in third at 116 mph at/around 7000 rpm.

If the tach read 7000 rpm at 116 mph, your tach may need to be calibrated. Normally, assuming 17x35x11 tires, 120 -121 mph is more typical of stock gears and tires.

Re-calibrating the tach is not a big deal for a DIY'er at all. If you have access to a scanner you can compare the analog tach reading with the digital scanner results and get back to us. OR...run the tach up and hold it on say 3500 rpm and give us the mph reading and the gear you're in and the tire size. From that we can get pretty close to the tach error, if any.

P.

[dredgeguy]

Originally Posted by Paul Workman

If the tach read 7000 rpm at 116 mph, your tach may need to be calibrated. Normally, assuming 17x35x11 tires, 120 -121 mph is more typical of stock gears and tires.

Re-calibrating the tach is not a big deal for a DIY'er at all. If you have access to a scanner you can compare the analog tach reading with the digital scanner results and get back to us.

P.

Thanks Paul,
As a newbee who almost turned his black interior brown going down the track, things were a blurr. I was in the area of 7000, the revs were moving quickly. I could have been at higher speed after the traps when I let off the gas and started to breathe again.