He has an LT1 and the stock gear ratios SUCK for LT1s.

L98s are a different story since they don't like to rev when they are stock.

Check out mojos results on his A4 with a gear swap. If GM would have offered the C4 A4 with 3.45s they would have built an awesome stoplight warrior that still had decent top end.



Mike

 

hi mike ,
do you think in your opinioun that the 3.45 rear ratio is a good all rounder in most combos with a 6 speed for street use of racing traffic to traffic lights ??

i have a 3.45 rear ratio and i have a 388 c.i high comp that im building up and i have with a 6 speed and was thinking i might need to upgrade to to either 3.73, 3.9 or 4.10 .
but may be i wont need to go 3.73,3.9 or 4.10 then!!
thanks

 

Nitrous. For less than $1000; nitrous is the largest gain in power, ET, MPH, and seat of the pants fun there is.

 

i am thinking if you are adding HP stay with the 3.45; anything more and the extra power will go up in smoke

 

First off what do you want out of your car? speed or quickness or somewhere inbetween

Until you state this, nobody can really help you.

 

You can get a nice brake kit for $1000. Why doesn't anyone do brakes?

I agree with austin above. You're not going to stop at $1000. I suggest laying out a nice plan right now for the next several mods you plan to do, starting with the ones you can afford to do right now. Keep it somewhere between a dream list and what you will honestly be willing to spend on the car. Clump items together as you make the list based on price and what will be disassembled at the time. These mods will build off of each other, no single mod will provide much benefit.

I think a good start would be to do 1.6 roller rockers, a cam, and headers. A tune after all of that would bring it to life.

The gear swap will definately make the car feel faster, but like some have said above it's really not going to be much faster. I have 4.10's in my LT1, I am saying this from experience. I'd trade it for a 3.73 or 3.45 today if someone offered.

Some other things to consider:

Electric water pump ($250)
Better spark plug wires ($100)
Larger Throttle body ($250)
Cat-back exhaust ($600 - 800)
Lightweight flywheel ($800) - not for the inexperienced mechanic
383 stroker with 16 psi supercharger...

 

i would like a bit of both, speed and quickness!!
so somehting in between i guess.
so as scaryfast mentioned above,3.45 or 3.73 may be the go then!!

 

Keep your top speed bragging rights

 

3.73's will kill your speed and melt your street tires.

 

No offense to anyone but 3.45 or 3.73 gears are a great first mod. The problem here is there are some L98 guys giving advice which is solid advice IF the o.p. had a L98 and he does not.

 

also we need just a bit more info on your car. Is it a stick or an auto? If an auto what rear-end ratio does it have?

Do you drive this car only on weekends or like me do you drive it every single day?

Are you mechanically inclined (like aboatguy)? Do you have a full set of tools? or like me do you work 6 days a week and just don't have time to enjoy being your own mechanic?

The answers to these questions will effect the answer to YOUR original question.


Unfortunately even though $1,000.00 is a lot of money it's not easy to gain significant (50+) additional amounts of RWHP in an LT1 engine.

On my 95 A4 LT1, I started with a set of long tube headers & stainless hi-flow RT cats ($1,150.00 for the parts) I won't tell you how much I paid for the installation.

A year later I went with the LT4 Hot Cam Kit $450.00 and a HD timing chain & sprocket kit along with new lifters.

Do NOT let people talk you into installing a high performance cam with out also changing the springs, retainers & lifters (I see you already have the roller rockers) with a better cam your LT1 is going to rev 500 - 750 rpm higher and instead of shifting at 5600rpm you have the shift point raised to say 6200rpm L98 folks don't even approach this kind of rpm (no offence to L98 guys)

After those two mods and a tune I gained 50RWHP over my base line.

But here is why the answers to the questions are so important ... if for examply you have an auto trans with the stock 2.59 ratio, for the money you have, you can have the OEM 3.07 rear installed and believe me the difference will seem like night and day. Just from that simple change you will feel like you gained 2 extra cylinders and this without a significant loss in gas milage ..... where a jump to a 3.73 will hurt the gas milage significantly.

 

They WILL NOT !! What do you THINK a 3.73 geared LT1 A4 tachs at 70mph ??

 

There is ALOT of BOGUS information in this thread. The o.p. has gotten good advice however he keeps getting the exact opposite from many.
I have proof of what a gear change will do in a LT1 car not speculation or my mechanics best guess. A quality torque converter would be another excellent mod for a LT1 that would not have an adverse effect on mileage IF that is a concern.

 

If the converter is a lock up, then yes it will not hurt the gas mileage to much. The OP said he wants both quickness and top end.
So, I would say since this is also my goal, I put on LT's with a mild cam and at some point going to put on 3:45 gears, from what I have read these are the biggest gears that can go into a D36.
Whathas been left out in cost is the price of the gear that drives the speedo.
Also, get a port job to really make the LT's effective.

 

 

3.73 or 3.75 rear gears will work with a D36. The gears for the speedo are less than $20.00 for both, the drive gear and the driven gear.
I THINK the o.p. has a 95 and the speedo can be corrected through the ECM if that is the case if it is an earlier car then $20.00 and he's good to go. The other side of this is camming an LTX is alot of work for a backyard guy. Pulling the D36 center chunk is a no brainer, pull the rear drop it off and have a pro set up the ring and pinion and reinstall. It's within his budget and will give the biggest s.o.t.p. improvement from any rpm. A converter would probably give a better reduction in e.t. though. Do both buy good tires and be prepared to have fun.

 

Before we start a posting war we still have not heard from the original poster on what transmission and gears he has. Also what is the intended overall purpose and future plans for the car? If it's a Dana 36 3.07 with an auto I would leave it alone and mod for hp. How many people with the Dana 36, swapped gears, torque converter, sticky tires, etc. start breaking things after modding for the launch? Probably less troubles with hp increases and easier to launch IMO. If it's the 2.59 I would consider changing gears. The 3.07 should have been standard in all LT1 vettes.

 

3.73 is too much gear for an A4 car that is used on the highway.
It should be the last mod, not the first. After he has final engine mods done he should look at gears. I guess if someone disagrees with you the info is BOGUS.

 

It is NOT too much gear for an LT1 A4 ask me how I know
I posted my personal experience with my 93 LT1 and the FACT that it went 12.50s with gears, converter and tires. My car tachs 2400 rpm @70mph on the highway which to ME is no big deal. Drive is a 1 to 1 ratio. Overdrive is .70 to 1 So a 3.73 gear running @.70 in overdrive =
a 2.61 final ratio. A 2.59 @ 1.0 ratio in [drive] = 2.59 IF some of you don't get that put your car in DRIVE on the highway instead of overdrive and that will be VERY close to what your r.p.m.s will do with a gear change.

 

You keep talking about 1/4, the op wants both 1/4 and topend. Not disagreeing with you, but on the highway you will loose 3-4 mpg w/3.45 as far as what I read on the forum from other members.
And I agree with BADDUCK, work from front to the back on mods. Gears and converters should match the engine, least thats what the experts say.