R6n350GT

im swapping to LS1 and 460le. Was thinking about 6l80e but too $...

Trailing arms have had the handbrake mount relocated to the top.

What gear ratio should i get. I currently have a 2.87, what is the best gear ratio and can i run a 255/60/17 tyre ?

I have got these wheels
Ridler 675 17x8 5x4.75" 0m BACKSPACING: 4.5"

Here are the tyres i can easily get.
Accelera IOTA 255/60R17 110V = 29" Vs Stock 27"
Cannot get 245/255/45/50 etc




I will have electronic dash so i can adjust speedo error.

With that in mind here is what i calculated in terms of RPM and final gear ratios etc

What is an optimal rpm for fuel efficiency and OD gear that will keep a 218/228 .604/.612 LSA 113 cam happy




<br/>4l60e final gear ratios using 2.87 Vs 3.54



Final gear ratio of 4l60e applied to the 2.87 and 3.54 diff gear<br/>



Stock gear ratios 2.87 Vs a 3.54 diff gear

71VetteLover

What is the operating range of your camshaft? To be "happy" your camshaft needs an engine rpm of at least the bottom of it's torque band. If for instance your camshaft is rated for 2000 to 6000 rpm you'll want at least 2000 rpm.

R6n350GT

W6store doesnt like the RPM range but a similar cam
218/228 .604/.612 113
218/227 .600/.600 112+2

RPM Range: 1600 to 6600

is that just relivant to 4th gear , what about idle as no gear ratio will be above 1600?

It seems 2.87 does have a few gears less than 1600 but the 3.54 and 3.73 both are above 1600... But will a 29" 255/60/17 Fit in the front and rear ??

gkull

The 29 inch and 4.75 BS will rub the frame lock to lock on the steering

Mine rubbed with 4.5 BS and 255/45/17. 9 inch front wheels. So I changed it to 4 inch BS

Because of the tall od gear most cars are happy with 3.73 or even 3.90 rear gearing

R6n350GT

gkull its 4.5"BS but will the rears work just not the front? with the lighter LS1 the front will sit up a bit higher anyways i think.

I can get a 235/65/17, its 0.7" smaller in width

tracdogg2

With that cam you will be lugging the engine with a 3.54 gear. You will do much better overall with the 3.73.
Mike

R6n350GT

I was hoping you would chime in ! W6Store who made the cam said either will work but 3.54 would be good.

Mike what tyre would you go for in my situation
245/50/17 Nexen N7000
255/60/17 Accelera IOTA

Or Iota in the rear and Nexen in the front ?

I did find only 2 Yokohama V801 255-50-17 but OLD stock like 2008/2010..

45 profile i think starts to take away that muscle car look... not sure if i should be considering that size.

tracdogg2

It would be nice if you find something in between. I would do Nexen on the front and IOTA on the rear but I don't like the tread design of the IOTA for the rear.

R6n350GT

And do you think is better than having 4 the same? Wpukd the iota rub on the front? Full locl is not that big of a deal? What's wrong with iota for rear. Look forward to your reply.

Is there a link n showing what rpm the 4l60e changes for each gear

tracdogg2

IOTA's are too tall for the front. Nexen's are under 27 inches, they may look a little small in the fender. The IOTA tread design is for cars with very little camber change, something our vettes don't have in the rear. More suited for a C4 than a C3.
No link, you just have to do the math. When calculating you need to remember it's not diameter but radius x 2. A 28 inch tire should have a radius of 14 inches but it doesn't. Weight of the car compresses the sidewall. You may have 14 inches from the axle to the top of the tire but from the axle to the road will be only 13.5 inches. So your actual diameter is 27 inches for your calculations.
With a lock-up OD trans you also have to compensate for converter lock-up which usually happens around 45 mph. Too tall of a gear will keep the lock-up "searching".
Cams have operating rpm's but they also have minimum cruise rpm. Below that rpm they get very inefficent. A 218-228 cam is not going to like running below 2200 at all. You will have lower dynamic compression with a larger cam which reduces VE at lower rpm.
Remember, you're trying to push a brick thru the air, not an arrow. Lower rpm = higher engine load= less fuel mileage.

Rotonda

Have you looked at the Riken (subsidiary of Michelin) in 255/50R17? 27 inch diameter like stock. Browse Tire Rack.

cv67

a 60 or 65 series tire in a 17 will appear to have a huge sidewall like an suv sure thats what you want?

mrvette

That what's on front of my '72, Limited the steering by sticking a bolt/nut in the lower arm rub/snub spot.....still less radius than a C4....so not too bad, never notice it.....in rear I have 275/50/17

on my '89 vette rims I kept the same centerline as stock rims, minimize loading on suspension parts.....had to move brake cable in rear, but that's ALL, and I have a stock rear swaybar.....

BTW, went to the tire store this AM, got on a rack to specifically check out welding on frame, it's all fine, was redone by P/O without grinding, so someone was a GREAT welder.....

lionelhutz

A LS1 with 4L60e could be driveable with the 2.87 gears, but if you want it to actually be fun to drive then you'll want at least 3.55 and probably 3.73 gears.

You can program the shift curves and lockup curve however you want for that transmission so it's fairly easy to set it up so you don't lug the engine.

Kacyc3

with 29 in tall tires a 3.70 gear is your minium, i have a 700r4 and 355s with 27" tire its 2100 RPM at 70 in lock up.

R6n350GT

I'm in Australia, Tyre size is very limited in 17" i have now found... I have to choose from these

And i was only thinking of high profile to keep the muscle look and fill in the guards.

old stock Yokohama V801 255-50-17
or new
275/40/17 FEDERAL SS-595
235/55R17 KUMHO KR26
235-50-17 YOKOHAMA ADVAN SPORT
245/50/17 Nexen N7000

What would you guys do....

mrvette

Couple-3 years old on the Chokeumamas is not so bad I would go that route, if not put 245/50 all around.....

gkull

I used to have a very light front end with the VB&P 550# one inch shorter spring. I bought 9X17 front and 11X17 rear. 255/50/17 and 285/40/17

then I went to 255/45/17 and 315/35/17 for a period of time

R6n350GT

Thanks everyone. I think i will go with

Rear
old stock Yokohama V801 255-50-17
new 245/50/17 Nexen N7000

Only 1.5% different in diameter and will fill guards.

so at 5500rpm change with 27" wheel in mph

3.54 gear
1st 40.78
2nd 77.04
3rd 124.8
4th 178.28

3.73 gear
1st 38.71
2nd 73.11
3rd 118.44
4th 169.2

for most racing through tight corners would be less than 118mph so with 3.73 gear ill be in 2nd, and over that in 3rd... With a 3.54 gear ill still be in 3rd until 124mph... im not sure which is a better scenario

gkull

I changed that to read correctly. Is 6 mph a big deal?

I sat for day's and did all the math on my above vette. I didn't have a 5500 rpm limit. I had started with 3.55 rear stock gears and already knew that it takes lots of power to accelerate at over 100 mph. You probably don't have the power to red line with 3.73 @ 169.2 mph. I figured out that the best gearing with an OD tranny is 4.11 if you have 7000 rpm and 28 inch road racing slicks and 3.90 gearing if you have a lower rpm motor