ruquik

iTrader: (1)

i have a 05 gto with a aps tt setup, i do race the car and currently i am running a ford 8.8 with a 3.55 rear gear. i am going to rebuild the rear soon and wondering if i should i stay with that gear or go to a 3.08 rear gear to load the turbos up. i run a m/t 265/40r18 drag radial tire

topend

i would stay with the 3.55 rear gear and see how it runs before i would do any changes. Turbos do not care what gears u run.

MY99TAWS6

iTrader: (3)

Heard the crap about lower numberical gears loading up the turbos better.
I went with 3.54 gears in my dana 60 they are lowest you can go. I have no complaints.The standard aps turbos spin up very quickly .I do have a 408 versus an ls2 but still. Going to likely upgraded LG turbos and expect a bit longer spool up. No big deal. At least the 3.54 have some ***** around town and off boost. 3.08 would be ok on the highway but horrible off boost. I would stick with the 3.55.
I have seen lots of aps cars running great with higher gears one on this forum was running 9s with 4.10s. And quite a few running diffferent turbo builds running great if you search the old boosted lists on here.

I see zero proof that the lower gears spool up the turbos that much quicker. And as said they are gutless off boost although they might help traction a bit.

engineermike

Tall gears "loading up the turbo" is an old wives tale.

ruquik

iTrader: (1)

thanks for the input guys, my new lg turbos should be here this week i hope.

gametech

iTrader: (1)

I beg to differ. Tall gears are actually used to offset inadequate traction for the total power being made. Uncontrolled wheelspin won't load the engine enough to produce full boost on a turbo setup. In theory, a better suspension setup would be the better route, however, this isn't always possible. I had almost identical times and trap speeds with 3.46 and 3.07 gears because the increased applied power offset the increased gear torque in my "not a drag car" car. The 3.07 gears, however, suck in daily driving.

crf538

iTrader: (3)

i feel like this subject has been beat to death way to many times.. it makes sense that a numarically lower will allow the turbo to build boost at a lower RPM however if ts an automatic i wouldnt think it would be an issue. with a M6 a numaricaly lower gear will make broader power in the lower gears (1&2) i dont see how this can be agrued either way. I run a 3.25 with my 4l80e because i like the street manors of this combo, although i think the car would be faster with a 3.50 or more

engineermike

Controlling traction and "loading the engine" are 2 different things. I do agree that a taller gear will help reduce tire spin. If the tires are spinning, why would you want to built MORE boost, though?

MY99TAWS6

iTrader: (3)

I think the key point is that really low gears like 3.08 suck for off boost around town driving although stall could help some in an auto.3.23 would be borderline ok to me for offboost and around town in an auto and 3.42 or so would be borderline for me in an m6.

Its so much nicer with an m6 to have 3.73 or 4.10 gears for general around town use that might have went to those ratios if was sticking m6. And you can build boost with m6 off the line quite siimply with antilag and two step like lingenfelter sells,standalones have these features built in usually like big stuff three.
Autos generally get into boost much better than sticks and of course a good stall is key there.
I went 3.54 as they should feel decent off boost and around town and also you want to take into account your trap mph without having to go into overdrive to optimize things if you care about 1/4 mile. Again from punching in numbers at my max rpm track limit think the 3.54 will work ok for me. A shift to overdrive isn't maybe the end of the world either unless a guy is really obsessive about that absolute best et.

I have 3.42 with 2800 stall in my 96z NA and its a nice overally around town combo.
Since its a heavy vert if was more into track would have gone 3.73 and mabye 3200 stall or combination of the above but again 3.42 and 2800 is a nice driveable NA and around town and highway setup for an auto. Had lots of experience was well with 3.73 and 4.10 in an NA m6.

Remember most of the time you aren't going to be in much boost around town unless you like jail. At least most people won't be unless they are street racers and that goes back to my jail comment.

So why not set up the car so it feels nice off boost and around town. I an can assure you that my car still can spool up wicked quick with the 3.54s. Will do some logs sometime to verify exactly how quick.

Cobra Commander

iTrader: (12)

Wouldn't you still want the highest numerical gear you can cross the traps with without going into overdrive, just like an NA car?

Loading up the turbos is what a 2 step is for, no?

RooRnZ28

iTrader: (14)

how about this one:

on my rear mount, with stock 2.73 gears, stock a4 and stall and LT headers, i would see full spoolup around 3000-3200 rpms at 8psi.

i swapped out the LT's for stock manifolds, put in a 3000 stall, and stepped up to a 9" w/ 3.25 gears, and my spool time is now 4-500rpms later but makes more overall power.

Below ~3000 rpms, it seems the old setup had better low end performance

Dyno Graphs

same tuner, same dyno. I believe my spool time/low end was directly affected by the different gears.

Opinions?

engineermike

Absolutely my point... Taller gears WILL make the turbo spool at a lower rpm, but not sooner. There is a difference. For instance, if you have an M6, put it in 6th gear at 1000 rpm and floor it. You'll find that spool-up takes place very early in the rpm range. You may even hit full boost at 2500 rpm. However, you're going to be waiting a long time for it. Now, put it in 1st gear with some 4.56 rear gears, and it might not spool until 5000 rpm, but it'll come a heck of a lot sooner on the stopwatch.

02anti_vnm

iTrader: (32)

... And the arguing begins! Lol this a horrible subject kind of like turbo cams one person says this one person says that... MY opinion is stick with the 3.55s a numerically higher gear in MY opinion is best that's y I run a 3.90 with my 347 t76 18psi combo. but in the end its really just try it out and see what works the best I say go with the 3.55s if you don't like it then drop down.

O and thanks again man for recomending Williams performance I spoke with them and that's def. The route I'm taking

1320

iTrader: (6)

This is a funny subject. I dont build race cars, so I use different criteria. My list goes like this.

1. Whats the budget? You cant do anything if you cant pay for it.
2. Whats the use? Racing? Street? hiway? etc etc.... Most of these type of cars see atleast some racing, some thats all they see. Some see NO racing.

Each would get a different solution to the question.

3. Is the trade off Worth it.....Is a 2300$ 9' with 4.10's and a 4000$ 4l80 good....Hell yea. But is the trade off worth it.......to a 2.75 geared 1300$ 9 inch and a 1600$ th400 which gets nearly the same performance on both ends for 1/2 the cost? That can only be answered by the end user and no one else.

Is a one set up ultimately better on a track....yea, but in the real world wee behind 300 fwd civics, in heat, with no track prep, instead of with nhra stock eliminator cars on preped tracks wih big tire cars as far as the eye can see.

Tiago

iTrader: (27)

I could not make my car hook on the track or on the street with 3.42s, using street tires (DRs) of any size. So I went to 3.08s.

I can't tell much difference in driving around out of boost.

But the oposite happened than I thought would. I figured it would spool the turbos up faster also, but it didn't. The RPMs don't rise as quickly as with the 3.42 gears so the turbos lag more since I am not getting in the sweet spot of the RPMS as quickly. But if I start a pull from the higher RPM already, it hits hard.

The problem is on some street driving the speed we usually take off from puts me in a dead spot in the power band and that sucks. If I downshift it puts me too high in the rpm and I'll spin again lol.

ruquik

iTrader: (1)

no problem let me know when you are going to the track. i will be down at nicks soon for another tune and up the boost alittle to see if the stock block will hold it till winter. then the games begin.

code4

iTrader: (30)

this always happens when it comes to gear ratio threads. it appears that everyone thinks that what they run is the best.

I run a 2.75 rear gear on a 28" tall tire with a turbo 400. My car runs high 9's in the 1/4 & I hope to be in the 5's in the 1/8 by the end of the year. I get 25 mpg on the hwy running 75 miles per hour. It' my car & I like the way it performs. Could I get more out of it with some other gear? Yes. Just like it if I upped the compression & ran race gas only, I could gut it for weight reduction, replace all the glass with lexan etc. etc. Making it a race car instead of what I use it for now which is transportation.

MY99TAWS6

iTrader: (3)

Well whatever floats your boat. JM on this forum ran high 9s at near 140 at fairly low boost with his auto and aps twin kit on 4.10 gears. And seen many fast cars on the old boosted list with 3.73 or 4.10 gears.

I can't imagine driving around on 3.08 or lower for daily street driving. They would just feel so weak and as said you are off boost most of the time in the city, at least my city.
They would be nice and quiet on the highway though.

Tiago have that mag somewhere but forget if you are auto or stick. And why can't you run a boost controller that ramps things in like the ams for example. I guess it also depends on where in the rpm band you are willing to accept traction. Sure I can spin even on fairly low boost and nittos on my car too in first and second and part of third. But that dont' really bother me much around town since not into street racing don't care.
If do want to play a bit more just put on some et street radials which will have mounted on second set of rims. Then can hook up much better. And even if you don't ramp boost you can still lower it and raise it when you have the better rubber and traction on the car.
I find my car not bad to control at 650 or so rwhp current estimate. I am sure it would be a more of a handful at 800rwhp or 1000rwhp but really don't see the need to dial things up that high again for general street use. But of course everyone is different .Some want to hook it up for street racing. Fines are too high around here for that stuff now with jail or impound two other possibilites. Just no fun anymore compared to the good old days.

Seriously though you guys think 3.08 or 2.73 feel ok off boost in town? Stall of course can help some with these lower gears. To me a really nice driveable gear for autos is 3.42 with a decent 3000 or so stall for autos and a 3.73 for m6s.
Since my car spends most of its time out of boost would rather gear it for that and not worry, car is plenty fast on boost and spools stupid quick with the 3.54s but agree traction on pure street tires or even nittos is a bit challenged.I have not used a ramping style of boost yet. Have eboost but its not hooked up yet.
Ams seems to be the boost controller to use but wasn't sure where to mount that thing.
Also a better traction control might be an answer too. I am looking into installing a racelogic variable traction control. They are used in some very high hp cars like twin turbo vipers,etc. Some guys say they work really well.

MaxxMitchell

iTrader: (15)

My experince with the 5.3 TC78 4l80: just changed gears a few weeks ago
3.23s - Street - Spun like crazy, would black track 1st and part of 2nd from a stop. Track - could brake boost easier on the line and cut 1.57-1.63 60s.

3.42s - Street - sticks way better, just hazes the tires in 1st. Track - Tried brake boosting and would just push the brakes, managed a best of 1.82 60ft, average 60 was high 1.8s

As far as driving around town, I cant really tell a difference between the gear change.
last year when I went from a 3.42 to a 3.23 on my 383 SBC/Nitrous set up the car spun worse on 3.23s and felt doggy driving around town.

MY99TAWS6

iTrader: (3)

Interesting about the way worse 60fts though.