Gear ratio

[Skipp65]

Hey guys, I have a 2011 ls3, I put 3:91 gears in it and after awhile I added a kraftwerks super charger. It hits rev limiter 1st, 2 nd and third. Should I go back to the factory gear? I love the throttle response but I can’t shift fast enough for the 3:91s.

[Pops]

Originally Posted by Skipp65

Hey guys, I have a 2011 ls3, I put 3:91 gears in it and after awhile I added a kraftwerks super charger. It hits rev limiter 1st, 2 nd and third. Should I go back to the factory gear? I love the throttle response but I can’t shift fast enough for the 3:91s.

How fast are you going at the rev limiter. If better than stock gearing keep them and shift faster. If slower change back.

[George-CZ]

Originally Posted by Skipp65

Hey guys, I have a 2011 ls3, I put 3:91 gears in it and after awhile I added a kraftwerks super charger. It hits rev limiter 1st, 2 nd and third. Should I go back to the factory gear? I love the throttle response but I can’t shift fast enough for the 3:91s.

I would recommend reading post 43.
And browse acammer's videos.



https://www.camaro5.com/forums/showt...=612002&page=4

[1JEWLDSSRS]

Originally Posted by George-CZ

I would recommend reading post 43.
And browse acammer's videos.



https://www.camaro5.com/forums/showt...=612002&page=4

Agreed.. It's not the gears, you just need to learn how to change your shifting to use them properly. The 3.91's are the go to gear to have. Good luck and read acammers info and watch the vids..

[acammer]

Sounds like it needs traction, not less gear ratio. What's the tire setup? What did it make for power?

[Ashen L99]

What kind of power does it put down? Does it hook in first and second? Need more info.

[Skipp65]

Thanks for the replies. Traction is definitely an issue,it has ZL1 rims and tires, can’t think of the size right now. Made 623/550. Because it buzzes through 1st and 2nd so quick I thought maybe the stock gear would help? Not wanting to race it, just a fun street car. Thanks for input.

[Royal Tiger]

I’ve had people say you shouldn’t go lower (higher number) than a 3.73 with forced induction, but I’m running an Eaton 3.91 and love it.

[Ashen L99]

Originally Posted by Skipp65

Thanks for the replies. Traction is definitely an issue,it has ZL1 rims and tires, can’t think of the size right now. Made 623/550. Because it buzzes through 1st and 2nd so quick I thought maybe the stock gear would help? Not wanting to race it, just a fun street car. Thanks for input.

Boosted cars= 3.73 or lower
N/A car= 3.91s or more.
I’ve had the 3.27s/3.91s then back to a 3.45. IMHO, anything more than a 3.73 for rolls kills your top end, plus with the additional horsepower you need the longer gear. The zl1 and 6th gen sticks all have 3.73s and they work. Your not trying to leverage the gearing like a N/A car needs to to get the most out of it, and If your not going to put a tire under it, your just breaking them loose that much easier with the 3.91s. So if it was me, I would put a 3.45 back in it, or if you can find a 3.73 diff out of a zl1 and put that in.

We could also talk about the wide ratio trans that comes in the fifth gen sticks and how GM should’ve just put the Narrow ratio in everything( which all 6th gen cars have as well as our 1le’s) but that’s a whole other discussion.

[acammer]

I take a little different perspective than Ashen L99. The OP has a stick car, with a small centrifugal supercharger. This is not a high power PD blower car that produces massive mid-range torque, it will still have a very "N/A" shaped power curve that favors rpm, and will absolutely benefit in terms of acceleration from the gearing that it has now.

We have not heard what tire is on this car, and I believe that's a key piece of information that we're lacking. If the car can zip the tire off in 3rd, that's not a gearing issue, that's a traction issue, and pulling gear out of the car is not a meaningful resolution. We don't know all the details about the build, but I'd guess it's in that 550-600whp range. Hooking a centri blower power curve at that power level is not super challenging with good rubber. If you want to run around on YangYen $100/tire cheapies, that's fine, I've done it - but don't expect them to act like a $400 high performance tire.

I wanted to think about the roll racing comment as well. I disagree about the "lack of top end". Lets consider the chart below, regular SS (M10) trans gearing, stock tire height, and a 3.91 rear end. We're capable of 152mph in 4th, and 181mph in 5th (@7000rpm). I'm not much into the roll racing scene, but I don't think that 600whp cars are doing pulls out past 180mph. That gearing is actually pretty perfect, you're going to get that 3-4 shift out of the way before the aero loads are really high, and you have that nice tight 4-5 shift where the aero load is much higher and a tight gear change to really stay in the power is hugely beneficial.

If you were to go to a 3.45 you'd pull third to 120mph, and then have that awful 3-4 shift recovery where the aero loads are higher, and ride 4th all the way out to 172mph, and 5th could take you (theoretically) to 205mph - I doubt the car has the power to even overcome the aero drag at that point.

ZL1s make the narrower MM6 trans ratio and 3.73 work because they have absolutely brutal mid-range torque with a positive displacement supercharger, and don't need to RPM like an NA/centri blower car does. As for N/A 6th gen SS cars with the narrow ratios and 3.73s - those are absolutely miserable to drag race. The starting line ratio is atrocious (9.9:1), you're trying to slip the clutch for like a full second trying to ride the exaggeratedly long line between wheelspin and bog.

If you take a look at dedicated drag race stick cars, you'll find they have starting line ratios (1st gear ratio times final drive ratio) in the 15:1-22:1 range. That's because without the benefits of a torque converter, you need an aggressive ratio to make those cars leave hard. Those ratios aren't very practical for a street car, but they give us some context for how much gearing you can get away with when the car hooks properly. A stock 5th gen SS (M10) or SS 1LE (MM6) have a 10:4:1 starting line ratio. A 5th gen SS (M10) with 4.10s improves that to 12.3:1, and my car (M10, 4.63fd) is 13.9:1. I can tell you that with good traction, that's not too much gear ratio, and it's still capable of 165mph in 5th gear, and cruises at 2300rpm at 75mph on the highway.

It all comes full circle to my original point - I think the core issue here is traction, not gear ratio, and I would start with a tire change rather than a gear change to find some improvement.

[dreksnot]

I like what Andrew has said. I've been all over the rear gear map with my ever progressively adding more horsepower with twins/cubes scenario. With the SS M6 I've ran 3.27 to 3.73 and enjoyed them both. With the SS M6 ratio, it pulled hard mid and high-RPM range. The difference was in the start-rolling and working the clutch to get going. I would spin the tires at 90mph with the 3.73 and 100mph with the 3.27 with higher boost and decent Michelin Pilot Sport 4S on the street but at the strip I ran with traction all the way down (drag tires and decent track prep). As I grew into more HP and twin sizes, I fondled with 3.25. Again, ran good after getting the car rolling (parking lots sucked and stop-and-go traffic was a chore). I wanted an easier start-rolling gear, got goofy and moved to a ZL1 M6 and 4.11 - drastic change. I figured I'd end up somewhere close to 3.70-3.89 gears (have 9" so the ratios are a little off) after the dust settled and in the long run. But, I'm really enjoying the 4.11's even with the mondo HP. I can now drive in traffic and parking lots with less clutching work, drag starts are better (still needs a lot of RPM to launch since the car is 4,450lb heavy), I haven't had to shift to 2nd gear with autocross (but I have tapped the rev limited a few times), and I've ran the Mile obtaining my speed goal of over 200mph in 5th gear (billet, not stock). On the road, I can cruise the highway in 5th or 6th gear (for that economy (jk)). It's easy to break the tires loose on the street with higher boost so I keep the boost set to the lowest setting so as not to end up in some ditch somewhere (est. 650-800hp). I've settled that down with a boost-by-gear boost controller (you too can install one in a centri car). Biggest factor appears to be the right-foot modulation though.... A centri is closest to the twins with how it delivers power compared to the other SC's. I've seen a post on FB from Carrol Shelby which I think should ring true in y'alls minds - "There is no such thing as too much horsepower, just not enough traction." The better advice to provide here is to make sure you tighten up your rear suspension - trailing arms, toe rods, bushings (diff and cradle), maybe LCAs and UCAs; and, for gawd sake, get good rubber to grab that asphalt before tearing into the rear gears. That's my nickels worth of advice (paid for by trials and learnings).

[Ashen L99]

Originally Posted by acammer

I take a little different perspective than Ashen L99. The OP has a stick car, with a small centrifugal supercharger. This is not a high power PD blower car that produces massive mid-range torque, it will still have a very "N/A" shaped power curve that favors rpm, and will absolutely benefit in terms of acceleration from the gearing that it has now.

We have not heard what tire is on this car, and I believe that's a key piece of information that we're lacking. If the car can zip the tire off in 3rd, that's not a gearing issue, that's a traction issue, and pulling gear out of the car is not a meaningful resolution. We don't know all the details about the build, but I'd guess it's in that 550-600whp range. Hooking a centri blower power curve at that power level is not super challenging with good rubber. If you want to run around on YangYen $100/tire cheapies, that's fine, I've done it - but don't expect them to act like a $400 high performance tire.

I wanted to think about the roll racing comment as well. I disagree about the "lack of top end". Lets consider the chart below, regular SS (M10) trans gearing, stock tire height, and a 3.91 rear end. We're capable of 152mph in 4th, and 181mph in 5th (@7000rpm). I'm not much into the roll racing scene, but I don't think that 600whp cars are doing pulls out past 180mph. That gearing is actually pretty perfect, you're going to get that 3-4 shift out of the way before the aero loads are really high, and you have that nice tight 4-5 shift where the aero load is much higher and a tight gear change to really stay in the power is hugely beneficial.

If you were to go to a 3.45 you'd pull third to 120mph, and then have that awful 3-4 shift recovery where the aero loads are higher, and ride 4th all the way out to 172mph, and 5th could take you (theoretically) to 205mph - I doubt the car has the power to even overcome the aero drag at that point.

ZL1s make the narrower MM6 trans ratio and 3.73 work because they have absolutely brutal mid-range torque with a positive displacement supercharger, and don't need to RPM like an NA/centri blower car does. As for N/A 6th gen SS cars with the narrow ratios and 3.73s - those are absolutely miserable to drag race. The starting line ratio is atrocious (9.9:1), you're trying to slip the clutch for like a full second trying to ride the exaggeratedly long line between wheelspin and bog.

If you take a look at dedicated drag race stick cars, you'll find they have starting line ratios (1st gear ratio times final drive ratio) in the 15:1-22:1 range. That's because without the benefits of a torque converter, you need an aggressive ratio to make those cars leave hard. Those ratios aren't very practical for a street car, but they give us some context for how much gearing you can get away with when the car hooks properly. A stock 5th gen SS (M10) or SS 1LE (MM6) have a 10:4:1 starting line ratio. A 5th gen SS (M10) with 4.10s improves that to 12.3:1, and my car (M10, 4.63fd) is 13.9:1. I can tell you that with good traction, that's not too much gear ratio, and it's still capable of 165mph in 5th gear, and cruises at 2300rpm at 75mph on the highway.

It all comes full circle to my original point - I think the core issue here is traction, not gear ratio, and I would start with a tire change rather than a gear change to find some improvement.

I agree with Andrew that OP should put a stickier tire on it before changing the gear ratio. A lot less hassle Than changing the diff, and it is the core issue.

BUT the OP said STREET CAR, which means no track, and very likely means roll racing if any racing. Maybe just OP is just doing pulls on the highway. A lot of these younger kids and new folk on the scene aren’t into digging. It’s not my cup of tea either, so it is what it is. Most folk won’t put a radial or slick on a dedicated set of wheels much less put one on The stocks. Therefore I’m assuming he is going to run linglong/ no name tires. Even with a decent street tire, 550-600hp will spin em pretty easy. Most people want to roll 40-60 to 130-160. most of em won’t pull overdrive either. I’ve rode and raced several C6 Zr1s with the amazing MH3 gearing. Most won’t throw fifth. And they are geared to throw fifth and sixth.


At 550-600hp, and with the m10 ratios, 3.91s are a bit much for a roll as anything above 40 and your at the top of second and immediately need to shift. Pretty tricky even for an experienced driver. And those linglongs aren’t going to hook in second. So that puts you in a awkward spot of trying to decide to start in second and: hit it/spin/shift, or start in third and ride it out, and play catch-up.

Honestly, 3.73s should have been put in all of the stick cars, it’s always been the best of both worlds. They figured that out later smh.

On the note of the sixth gens/ ZL1s, again I’m talking about roll racing. you want the narrow ratio when your already moving. A great example is a 10 speed 5.0/ Camaro. with a 7.39/1 overall spread it does everything well. Digs or rolls. Now the gap on the Camaro is less, but mod for mod, it will eat its stick counterpart. But why? The stick will put down more power to the tire…and they’re lighter if the cars are optioned the same way… so it’s got to be about the gearing obviously!

Now a stick Camaro is a lot closer with its 10 speed counterpart than the 5.0 is, and you can attribute a little of that to the fact that it makes extra torque over the 5.0 matchup. But what is the one thing FORD did to the 3rd Gen S550 stick cars? They put a wide ratio, D4 gearing, MT82 in it. What’s funny about this, is that a 3.31 D3 2nd Gen S550 vs a 3.55 D4 Gen 3 S550, tuned by the same people so that’s not a factor, the gen 2 will walk the gen 3 and has less HP. Seen it many a time. Now On the Camaro side of things, it has the narrow ratio, and I’ve seen it go either way.

Point?: narrow ratio for racing, wide ratio for everyday cars.

[Skipp65]

Thanks all the replies , good info for sure. I will try some different tires in the spring and if it’s not much better I will put the stock gears back in. Maybe an automatic ZL1 is in my future? Lol