PPG Sequential Gear set ratio

[cwylie]

I'm considering going to a full sequential after driving the car with an S1 Sequential shifter for the last year. I really dont know what gear ratios to go with. The car is a 69 Camaro, LSA with a 2650 blower making 800ish rear wheel. In running a 26 inch rear tire. Im currently running a 3.80 rear gear but that will be swapped at the same time as the transmission.

I was told the 2.437, 1.611, 1.228, 1.000, 0.875, 0.777 gear set was the most street-friendly. PPG recommended the 2.589, 1.841, 1.438, 1.168, 1.000, 0.777 gearset.

Here are all the options though:

2.148	1.561	1.228	1.000	0.875	0.777
2.148	1.561	1.228	1.000	0.797	0.634
2.437	1.611	1.228	1.000	0.875	0.777
2.437	1.611	1.228	1.000	0.875	0.634
2.946	2.071	1.438	1.000	0.875	0.634
2.946	2.071	1.438	1.000	0.875	0.777
2.589	1.841	1.438	1.168	1.000	0.777
3.255	2.148	1.561	1.228	1.000	0.857

The car is mostly just a fun street toy but I do want to do some auto-x or road course events in the future. Thoughts?

[cwylie]

The 2.43/1.611/1.228/1.00/.797/.634 with a 3.5 rear gear might be the sweet spot. With the 2.43/1.611/1.228/1.00/.875/.777 I feel like I would need to run a 3.25 rear gear to keep my cruising RPM (2500 at 76mph in 6th) down which would make first pretty long. Or the 2.589, 1.841, 1.438, 1.168, 1.000, 0.777 with a 3.0 rear gear which would put me at just under 2500 rpm at 80.

[Lonnies Performance]

How big is your camshaft?

I can say from experience with the torque of the LSA, much more than a 3.5 gear and/or too much first gear & you first gear will be very short.
I'm currently running a 4.10 with 2.66 1st & 27.5" tire... I'm dropping to a 3.54 this year. The 4.10 was great with a LS3, but the LSA charger makes my 1st gear almost useless.

The other ratios that make 5th 1:1 only seem fitting for a high RPM/narrow power band engine.
You can obviously use a wider spread between gears with massive mid-range torque.

The 3.5 with a 2.43 first sounds appealing, but I like the .634 OD for highway cruising... how low can you lug your engine before it gets upset?
My 4.10 with a .62 OD puts me at a 2.54 overall & I wish it had less gear on the highway at 70+mph.
Keep in mind your tire height, in comparison gives you an effective .2 more rear gearing than me... meaning a 3.54 with 27.5" tires is like a 3.36 with 26" tires.

[cwylie]

I have ruled out the 1:1 5th as even with a 3.0 gear the highway RPM are too much.

Im running a BTR stage 3 PDS cam. It really kinda likes to be above 2k but that could probably be improved a little with the tune. Im between these two gearsets now which have a more OD.

2.148/1.561/1.228/1/0.797/0.634 with 3.70 rear gear

Or

2.437/1.611/1.228/1/0.797/0.634 with 3.50 rear gear

The 2.148 with a 3.70 gives me a little longer first but a little more RPM on the highway (still under 2500rpm at 80). I don't think the 2.148 would be any issue with all the midrange the blower motor has. If I ever wanted to change things up in the future and go N/A it might be a little tall.

[Lonnies Performance]

I think from a drivability standpoint the 2.437 with a 3.50 would be my choice.

Especially normal driving as even old school close ratio transmissions with a 2.20 low were more suited to 3.73 or greater gears.

[Hotwire]

Don't know if this will help, but I love using this calculator, gives you a great visual of mph/rpm over the entire range. Might give you a better feel for your choices over the spreadsheet style you're using above? I used it to help determine shift points in my setup.

https://www.blocklayer.com/rpm-gear

I'm running a TUET2066 T56 (2005 GTO takeout), love the gear setup but there are times I'd want a little closer spread like what you're looking at. It'll help you stay in the upper rpms on road courses, the longer 1st will help w/ short courses like Goodguys shows.

2.97 - 2.07 - 1.43 - 1 - .84 - .56

[cwylie]

Thanks for that link. That was helpful. After looking at the shift points and RPM drop Im leaning towards the 2.148 gear set with 3.70 or 3.90 gears.

https://apx6u.app.goo.gl/XRYh

[Lonnies Performance]

With your power level, and a 3.70 or 3.90 gear, you will need to shift to 5th in the 1/4 mile if you do any drag racing.