Bogan Edition Z28

In overdrive in my 99 with a4 and 2:73s.3000 stall. I find I never use OD unless rolling down the highway.

I have longtubes, cam, LM2 no cats and at 75mph on O95 it is almost quiet 😂

I need 3:73 like yesterday.

RPM WS6

iTrader: (3)

I wouldn't even consider a 2.73 to 3.73 gear swap in this application until/unless stall speed has been optimized - that's where the real gains lie, and many folks find that the stock gears are just fine once they move to a ~3500 stall speed. At that point, any additional measurable gains are limited to about ~1 tenth of ET reduction, so the only real benefit to the swap is to tighten up part throttle feel (which is often a non-issue for lots of folks, assuming they go with a top shelf/high quality converter).

On the other hand, if you just want to cruise at a higher rpm on the highway then I guess a gear swap is probably in order (though I really can't understand why this would be desirable) - or you could just cruise in D (3rd).

B52bombardier1

Yea, I cruise around town in third with my 4L60E and only go to OD on the Interstate. Also 2.73 gears here. Ya' gotta' love 27-28 MPG in a 51 year old heavy cruiser El Camino!!

Rick

Bogan Edition Z28

I do have a 3k stall. I edited first post.

RPM WS6

iTrader: (3)

3000rpm stall speed is a bit low to be optimal even for a stock LS1, so you're definitely leaving something on the table with an upgraded cam at that stall speed. A unit in the 3500-4000 range would provide some noticeable gains.

Personally, I actually prefer a numerically low gear ratio (3.23 is ideal IMO, but even 2.73 is fine especially for a light car) with a higher stall speed as long as the application has a relatively aggressive internal 1st gear ratio (such as a 4L60E). That way you get explosive acceleration at WOT while still having the benefit of low cruising rpms at steady speed. It's the best of both worlds, unless you're one of the folks who is bothered by the part throttle "looseness" of a higher stall speed with a numerically low gear ratio.

Bogan Edition Z28

Thank you for the advice. I'm just learning about stall at 53 years old 😂
This is my first LS too.

RevGTO

iTrader: (12)

Depends on the converter, but with a cam I agree 3000 is too low. A 10" 3000 converter is going to perform differently than an 11" version. My TCI 3000 and Yank 3600 were almost indistinguishable, except the Yank would flash 500rpm higher at the track.

I agree that 3.23-3.42 makes for the sweet spot in an A4 4th gen. They are also virtually indistinguishable. The difference between 3.42 and 3.73 is slightly more noticeable.

Bogan Edition Z28

Yeah this new manual BMW smoked my *** today from a 30mph roll 😥

lucky94msuk

If the car actually has gearing that allows 70mph at 2000 rpm then it's fine - provided the engine isn't labouring.

It's a ‘how long is a piece of string’ question

It's definitely NOT good for the engine to be kept at the bottom of its rev range all the time regardless of load. This over stresses bearings and is poor for fuel economy. If the car has a computer that gives instantaneous fuel consumption figures you can prove it to yourself.

It does an engine no harm at all to red-line it occasionally (not when stone cold), in fact lugging a diesel with DPF at 2k rpm is a good way to block it.

FirstYrLS1Z

iTrader: (4)

What brand and model ? Big difference in performance between an 'off the shelf' $400 unit and a custom $800-900 unit.

Torque increase to 'pavement' with a gear change
2.73 - 3.23 = 18%
2.73 - 3.42 = 25%
2.73 - 3.73 = 37%

A good stall generally/typically lessens the need for a gear change, but if maximum performance is wanted then a gear change after a stall would do it.

Bogan Edition Z28

Getting my 3.42s installed next week. Along with Strano springs and yellow Konis.

RPM WS6

iTrader: (3)

3:42 would be a terrible gear ratio unless perhaps you were looking for 1,000,000mph top speed and didn't care at all about how long it took to get there.

On the other hand, 3.42 (3.42:1) would be a much better choice.

Sorry, just a little technical teasing to end the week.

Bogan Edition Z28

You mean I can't hit that top speed. Dammit to HELL!

Need4Camaro

iTrader: (1)

Wanting to capitalize off this thread. I have a BTR Stage 2 cammed LS3 4th gen with the stock 3.23 rear end and a YANK 3600 Stall... Cruising around it can feel like a dog but stomping on it will plant me in the back seat... ...Would I benefit by going up to 3.73's when I swap to a MWC or should I stick with 3.23's ?

FirstYrLS1Z

iTrader: (4)

3.23s' to 3.73s' would increase torque to the 'pavement' by 15%. 15% is a small percentage increase and it would still feel like a dog. For example, a 300hp car increased by 15% would then be 345hp and both would feel the same cruising around. The difference would only be felt upon opening of the throttle body as you stated by 'but stomping on it will plant me in the back seat'. My 4.56s' feel the same as my 3.23s' just cruising around but a slight increase acceleration is when the difference is felt.
Having an A4, why do you feel you need a new rear end ???

Need4Camaro

iTrader: (1)

Peace of mind, I haven't really tracked the car but if I ever do and it hooks I just don't want it to grenade. I hear they break when you hook up and imagine the stall wont help matters.. and I also hear they take things like the tranny and other drivetrain components with them when they go boom.

Given its not tracked very often, Im guessing I should just stick with 3.23's and retain the fuel mileage (or whats left of it) ?

FirstYrLS1Z

iTrader: (4)

2.73s' were window stickered at 27mpg freeway, 3.23s' 25mpg. Had they had 3.73s', probably would've been 24mpg.
My 3.23s' on 8 trips to Florida from Cleveland Ohio got 24.5mpg freeway travelling with existing traffic on the interstates. With the 4.56s' (yes 4.56s' Ohio to Florida) 4 identical trips got 21.5mpg.

Bogan Edition Z28

I'm going from 2.72s to 3.42s because I enjoy wasting money.

Need4Camaro

iTrader: (1)

Why not 3.73's?

Bogan Edition Z28

So I drive a bit on the highway. The 2.72s just seem to lug the engine a little more than I like @80ph in OD.
I think the 3.42s will help enough.