Performance Upgrade

[ramrod]

I have a 93' Automatic - Convertible with 35K miles. Currently no significant mods other than DynoMax exhaust and K&N filter.

I am considering a performance chip and was wondering if this really makes any noticable performance difference. If so, can someone recommend a good one. If not, can someone suggest an alternative short of opening up the engine.

Thanks.

 

[Ken]

Here are some links to get you started Rod.

http://corvetteactioncenter.com/for...threadid=17360&highlight=Performance+Upgrades

http://corvetteactioncenter.com/for...&threadid=7855&highlight=Performance+Upgrades

http://corvetteactioncenter.com/for...threadid=10070&highlight=Performance+Upgrades

http://corvetteactioncenter.com/for...threadid=11042&highlight=Performance+Upgrades

Others will offer their advice here soon. Good Luck.

_ken

 

[c4cruiser]

Exhaust and a K&N filter may get you 10-15 HP total. What sort of performance are you interested in? If you want quicker acceleration, it's gears, gears, and gears. (Did I mention gears?).

The gear ratios offered in the roadster were either a stock 2.59 or the optional "performance axle" 2.73. Look for RPO GU2 and G92 to see if your 93 has the performance ratio. GM1 is the standard 2.59.

Changing to the performance ratio available in the 6-speed car (3.54) will wake the car up a bunch. Unfortunately, the manual transmission cars were equipped with the Dana 44 while the automatic cars were equipped with a Dana 36. This will be an expensive change, possibly in the four figure area. You may lose one or two MPG with a gearset change like this and maybe a few MPH on the top end. but it will feel like a different car.

With the 2.73 gears in my 92, I have seen 160 on a couple of occasions and I do open track events where I can hit upwards of 130 in 3rd gear (auto) on a 3/4 mile straight. I like to autocross and I've even grabbed a couple of trophies. Most autocross courses are either low or second gear with an auto. On the street, I do have problems keeping the car in a straight line if I mash the loud pedal off idle. I'm not really a drag racer anymore, but I do know that mid-high 13's are easily doable with an auto LT-1. Gears like the 3.54's above would get you into the low 13's to high 12's with drag radials.

I don't believe that there are many "bolt-on" components that will bring large HP gains. Stay away from bigger throttle bodies unless you do internal mods (heads, cam). The little plastic airflow thingy is a waste of money. You can open up the air filter lid for a few HP, but you do need the exhust flow out the other end for that to work. Long tube headers work, but getting the cats connected is a beech! Upgrading the injectors to around 24lb units helps, but you need to adjust the fuel pressure for best performance but if you don't have the internal mods to help with the increase in fuel delivery, it may not be worth it.

You can install a 160 thermostat and rig a bypass hose around the throttle body. That can be worth a couple HP.

 

[vettn94]

Changing to the performance ratio available in the 6-speed car (3.54) will wake the car up a bunch. Unfortunately, the manual transmission cars were equipped with the Dana 44 while the automatic cars were equipped with a Dana 36. This will be an expensive change, possibly in the four figure area. You may lose one or two MPG with a gearset change like this and maybe a few MPH on the top end. but it will feel like a different car.

c4Cruiser is right, a gear change will make a significant improvement in performance and will probably be one of the best mods you do. As for loosing MPH I disagree. When I switched from the stock 2.59 to a 3.54 gear in my convertible I saw a gain of amlost 5mph in the 1/4 mi. with a drop of over 5 tenths from my ET on street radials.

There are just as many bolt-ons available for Lt1 car as any other (L98, LS1) and it depends on who you talk to as to what's considered a "bolt-on". Heads & cam may be considered a bolt on to alot of peple.
It's hard to make suggestions without knowing what are your plans are for the car, how fast you want to go ?, street or strip ,what kind of $ are you looking to spend ? Give us some more specifics and I'm sure we can make some good suggestions.

My advice, a good place to start is with a good tune up.
You're not going to see much gain from an aftermarket chip, however the biggest benefit would be getting the fans on earlier.

 

[Justin_cv87]

Im gona need this thread in the feautre, so ill just book mark it now!

 

[c4cruiser]

vettn94-- Sorry, I was referring to a loss in top speed, not trap speed. 5MPH gain through the lights is a good increase!

 

[Edmond]

There really is no easy way huh?:L :L :L

 

[vettn94]

vettn94-- Sorry, I was referring to a loss in top speed, not trap speed. 5MPH gain through the lights is a good increase!

no sweat. I was pretty happy with the gear change, of course anything is better than a 2.59 -lol

 

[BlackNBlue95]

no sweat. I was pretty happy with the gear change, of course anything is better than a 2.59 -lol

I hear that... I can't wait to try out my 3.07's just a small upgrade but the price was right!!! you can pick up a used setup for cheap.. I my ideal is probably a 3.73 set.. you can buy just the gear set for around 300$ new I think.. or you could find a used setup for cheap as well i bought my 3.07's for 365 with the carrier and cover(bat wing) and that included shipping.. so it was worth it.. I definitly agree the gear will give you the best bang per buck on these cars..

-Rick

 

[ramrod]

Reasons

My #1 desire is NOT top speed but pure acceleration. I don't mid giving up a few MPG, however, neither do I want to get too extreme ( no cams, etc. ).

Assuming I am looking for pure acceleration, it seems that the consensus is a gear change. I assume this also infers I shall have to recalibrate the speedo ....how about the tach?

Can I assume that installing the 2.73 gears ( mine is standard 2.59 ) is fairly straightforward ...anything ( other than gauge recalibrations ) extra that's needed in conjunction with gear change? Is this something any GM dealer would have? Any idea on parts cost?

The vehicle is pristine and was maintained to the letter by previous owner ...my only "problem" if you want to call it that is that the vehicle seems to run hot with the A/C on in stop & go driving. That said, this is a problem I've had with my previous '69 and a subsequent '78. Can I assume that these aftermarket chips can help in this department by turning fans on earlier?


Rod.

 

[ramrod]

Follow-Up

One other thing ...is there a significant/noticeable improvement in acceleration with 2.73 gears over the stock 2.59?

Rod.

 

[c4cruiser]

The 2.73's will get you some improvement, but something like 3.54 or even 3.73 wil be like night and day difference. To go above the 2.73 gearset you will need a Dana 44 differential. There are a number of suppliers that will have these set up and ready to install on an exchange basis. Expect to pay around $1500 for one that has new ring and pinion, bearings, clutches, and professional set-up. Speedo change is a just a drive gear in the transmission tailshaft. The tach is just a function of engine RPM so no changes there.

As far as engine temps, what temps (on the digital gauge) do you see? My 92 can reach temps of 225-228 in stop and go driving on warm days. Once the A/C is turned on, that forces the 2nd cooling fan to run all the time. If you see high temps without the A/C on, turn it on and temps should drop quickly back to 197-200. LT-1's normally run just under 200 degrees. Unless you see 225 and higher constantly, I wouldn't worry too much.

You should check the area in the lower front of the radiator to see if debris is present. A clogged A/C condenser or radiator will cause high temps. Even though the car only has 35K on it, a cooling system flush wouldn't hurt, Install a new 180 degree thermostat, too. If the cooling system is not up to par, an aftermarket chip won't do anything.

If drag racing is on the agenda, you may also want to consider a high-stall torque converter. That, of course, requires transmission removal but something like a 2600-2800 converter with 3.73's and drag radials may get the front wheels off the ground!

 

[ramrod]

Thanks

Thanks for info C4Cruiser ....Radiator has been flushed every year since new ( brake system purged regularly also ) ....I have been seeing close to 230 on a hot day in stop & go W/O the A/C on ....I figured A/C would make things worse! Area under radiator is clear.

Do these aftermarket chips force the second fan on early ....is there a better way to engage the second cooling fan w/o using an aftermarket chip or A/C?

I am VERY hesitant to go with a 3.54 or 3.73 due to the need to change differential ....I just dont want to stray TOO far from stock. If I can see a noticable "seat of pant's difference" with the 2.73 I'll go that route.

Drag racing is definately NOT in picture ...just a personal desire to feel more "seat of pant's" acceleration.

I guess I just have fond memories of the old 69-71 Charger's / SuperBee's and 383 Challengers ....what a thrill they were! I took a 440 Charger down a country road in England in the late 70's with my foot buried ( for 15 - 20 seconds anyway ) ....experience I'll never forget ( nor shall the locals I would guess ) !

Rod.

 

[ramrod]

3.07

C4Cruiser ...is there some reason I cannot use a 3.07 ratio with the stock Dana 36 ?

That should be a straight gear swap without differential change right ?

Rod.

 

[BlackNBlue95]

Re: 3.07

C4Cruiser ...is there some reason I cannot use a 3.07 ratio with the stock Dana 36 ?

That should be a straight gear swap without differential change right ?

Rod.

I think he mis typed 2.73 instead of 3.73 you can put upto a 3.73 in the dana 36 summit offers a gear set for i think around 300 bucks but you can shure find one for sale online used.. but that depends on how you want to go.. putting a 2.73 in instead of a 3.54 or higher.. is so small it's not worth the trouble or removing the carrier.. think 3.54 or 3.73 I think 3.73 is the best best if you don't care about going 170mph and don't want to tear apart the engine at all that is the best mod you can do for the money... oh also a torq converter is a good one as well.. higher stall speed lets you fly back in the seats from a stop.. and will improve your 1/4 mile time..
-Rick

 

[vettn94]

First off going to a 2.73 is going to be a complete waste of time IMO. You will definetly not see a sotp difference. If you're concerned about going with too much gear then stick with the 3.54.
You can get a Dana 36 with a 3.54 or 3.73 gear. I paid around $1200 for mine outright, no core from a place out east. Zip products sells them in the $800-$900 range I believe on an exchange basis.
If you're planning on doing alot of drag racing you may want to consider going to the beefier Dana 44 rear with a 3.45 gear. You can find them used for about the same price you'll pay for a 3.54/3.73 Dana 36 with all new parts.
You can have someone install either gear in your current rear but it will cost you just as much and IMO you're better off buying a complete rear.
If you switch to a Dana 44 you'll need the cover with it and I believe driveshaft as well, they are different than the D36.
The only reason I would get a stall converter is if you plan on drag racing, even at that worry about it later. The gear will keep you plenty happy.
my advice is to do the 3.54 gear.

As for your car running hot, mine ran the same when I first got it. I immediately installed a 160° thermostat and reprogrammed the fans to come on earlier with a Hypertech Power Programmer. It made a huge difference. My car rarely ever goes above 200° in the heat of summer w/ the AC on.
Since you have a 93 you could just replace the chip instead of using the programmer. email Jeff : vettn89@yahoo.com
He might be able to help you out with that.
OR you might be able to use a fan switch on your 93. Check with Jeff first, he can probably do that chip for you pretty reasonable.

 

[ramrod]

Gears1

Let me understand this ...I can put in a 3.54 or 3.73 gear set in the existing rear end - no diff. replacement ?

Currently I see about 1800 RPM at around 65MPH ...any idea how a 3.54 or 3.73 rear end will change that ?

Finally ...any tips on a location for NEW parts ...I want the baby to have the best!

Thanks guys ....if the RPM's dont go too high and assuming I can use the existing rear end I think I'll do this.

Rod.

 

[vms4evr]

ramrod,

here are the MPH/RPM using 2.59, 3.54, 3.73 gears. you judge for yourself which you can live with. if you do a search for gears you will find a ton of info.

http://corvetteactioncenter.com/forums/showthread.php?s=&threadid=9178&highlight=gear

i'm running the 3.54 in the stock dana 36 carrier and i'm very happy with the outcome.

graham

 

[ramrod]

Gears

Graham ...thanks for info link. I am begining to see why folks like 3.54 ...did you notice a significant difference in acceleration over stock ?

Did you put in a whole new diff. or just replace the gears in the stock one?


Rod.

 

[vms4evr]

ramrod,
the original diff with the new 3.54 gears. and yes the acceleration is like night and day. with 3.73 even more. and the car will still make it to 150 but in OD instead of D.
search for gear and my id and you'll find a lengthy post on what i did, part numbers etc...
for the money it will wake up that auto and make it move more than putting a grand anywhere else in that car ;-)
graham