I have a LS7 motor in my 32 truck. I have headers, custom grind cam motion cam. Trunnion up grade. The cam size is between a BTR stage 3 and a BTR stage 4. 240/252, 654/ 640 113 +3. My heads have been fixed by WCCH. But I did not mill them. And I have a tune. My rev limiter is set at 7500. I was shifting at 6300RPMs before the new cam, and trunnion up grade. I run a tb400 manual valve body. So I can shift where I want to. I am going to try a higher shift point. SO I WAS WONDERING WHAT YOU GUYS SHIFT AT ? At the track. Thanks Robert

 

Have you dyno'd it? If so knowing where your peak is gives you a good starting point, also just knowing whether it carries or falls off entirely after that peak, otherwise just rev it till you feel it fall off, mark that rpm then shift just before that.

 

You always shift briefly after peak hp, regardless of what your engine is. If your peak hp is higher than your rev limit, you built your engine wrong.

 

No mention of intake manifold. Your intake is going to dictate where the engine peaks.

 

Super victor EFI carb style. With ram air setup I made. I will try and find some pictures. Of the setup. With factory DBW TB. Truck HP peaked at 7000.

 

Here is one picture. I will try and find one of the intake.

 

And here is the intake setup.

 

Ah so you have a graph. You can play with this:
https://glennmessersmith.com/shiftpt.html

 

Thanks.

 

Given the 2.48 1st and 1.48 second, plus your setup peaking at 7k, you'll probably want to wind it up as much as you're comfortable in first. 2-3 most likely the same. Remember you want as much torque as possible so depending on how quick your motor falls off up top and what is makes down around 4k will be the deciding factor.

 

Just plugged in my chassis dyno numbers for my LS7 with a 2004r trans (2.74 1st, 1.57 2nd) and it gave me 6800 rpm shift points for 1-2 and 2-3. My cam is 242-258 @.050 and I have an MSD intake.

 

I have always shifted at 6800 or 7000 (just touching the rev limiter). So I guess I've been pretty close just by guessing. Best et 10.29 @ 130, 3300 lbs, 3.90 rear gears. Through full exhaust, driven to the track.

 

The linked calculator explains a bit of the theory behind optimizing shift points for acceleration. Basic physics -- F = M x A A is acceleration, M is Mass and F is force. The force applied to the pavement by the tires comes from the torque created by the engine/gearing. So to maximize A (acceleration) the goal is to be able to shift gears in a way where the highest AVERAGE F (torque) is applied across the entire 1/4 mile run. The results can be a bit counterintuitive depending on the torque curve of the engine and the gearing splits. I'll just say more sub-optimal ET's have been run by shifting at too high an rpm than by shifting too low.

Back in the day, spent a bit of time road racing SCCA Show Room Stock C4 Corvettes. Peak hp at 4000-4200 rpm; peak torque at 3200 rpm. You could hold 'em to 4500, 5000 even 5500 rpm (5500 where the redline showed up on the digital tach). And there were drivers that thought higher revs must be faster - you should shift at redline, right? If you were running by yourself and not worried about having to defend a pass or making a pass (qualifying) - out best lap times came shifting the cars at about 4000 rpm. Pushing them higher than that made more noise and you went slower. Sounds exciting doesn't it. The old smog motors were more like diesels.

 

I have an LS7 with a similar cam (240/254 114+3). The torque swells above 5K rpm and you can feel the extra push. I usually shift somewhere between 6800 - 7000 rpm. Yours might carry higher with the single plane intake, but I have little better heads so who knows. Mine feels like it's starting to tap out around 7300 rpm. I think maybe the practical limit of a SBE LS7 is 7500 rpm (?). I'm not a real racer though, I don't beat on my stuff too hard and I'd rather it hold together than chase after a few tenths.

 

The first time out. I hit the 7500 rev-limiter fast. I thought something was wrong with the truck. Turned out that my great grandson. Had set my shift light over 10,000. And I was hitting the limiter and shutting down, so the light never came on. Took me a minute, to figure it out. So it never did lay over.