Anyone done any real life testing or gear ratio diff with turbos?
07-07-2007, 11:42 PM
#1
Anyone done any real life testing or gear ratio diff with turbos? I keep hearing go with lower ratio like 3.42 or in case of planned dana 3.54?
but I think still want to go with 3.73 for clutch and for driveability around town off boost.
How bad really in say the 1/4 mile would the 3.73 hurt me over the 3.42 or 3.54 and since car is pretty much just a street car I would think it would matter even less. So lets here if from some of you mostly street guys with similar turbo setups to what I am planning . Planning APS twins with eventually bigger engine 408 or possibly 427. Again more into street toy less into race car.
but I think still want to go with 3.73 for clutch and for driveability around town off boost.
How bad really in say the 1/4 mile would the 3.73 hurt me over the 3.42 or 3.54 and since car is pretty much just a street car I would think it would matter even less. So lets here if from some of you mostly street guys with similar turbo setups to what I am planning . Planning APS twins with eventually bigger engine 408 or possibly 427. Again more into street toy less into race car.
07-08-2007, 12:59 AM
#2
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Ive run 3.50's, 3.42's and a couple others in various turbo cars. They have always been faster gong to higher gears (lower numerically). I have several turbo cars around now, 2.73's,2.75's , 3.00's and 3.25's.
Way better cars and more drivable. 3.15's with a z06 trans is nice too.
Way better cars and more drivable. 3.15's with a z06 trans is nice too.
07-08-2007, 10:04 AM
#4
I thought its more complicated than just the math Do you have site for the gear tables. Also not sure what rpm my gt7 would rev too. I would think 6800 to 7000 redline but not sure if that would be necessary or smart? So the main problem with higher gears and turbo will be that might have to make another shift to 5th in 1/4 mile? What about the higher gears affect on spooling.
Maybe should have asked who is driving around on 3.73s on street with similar turbo setup and what complaints do you have with the gear ratio.Again not a track car but don't want to kill my 1/4 mile times too much. A tenth or two slower don't matter much. A full second might.
Maybe should have asked who is driving around on 3.73s on street with similar turbo setup and what complaints do you have with the gear ratio.Again not a track car but don't want to kill my 1/4 mile times too much. A tenth or two slower don't matter much. A full second might.
07-08-2007, 11:18 AM
#5
I've used 3.42, 2.73, and 3.00 gears with my turbo/TH350 setup. I like the 3.00 the best, but that's because it's geared nearly optimal for the quarter mile. In Drive, I'm going through the traps at about 6300 rpm (power peak is at 5700) with a 26" tire at 146 mph. The 2.73's didn't 60' as well and had more rpm left at the end of the track. The 3.42's blew the tires away in 1st gear and ran out of rpm before the end of the track. BTW, this car is 95% street.
Mike
Mike
07-08-2007, 11:45 AM
#6
I might go to 480 auto but so far trying to stay with m6. Any reason I can't run my rpm higher to 6800 or 7000. Or would my high lsa gt7 not work good up there like my current non turbo cam b1 with 114lsa that likes to be shifted at like 6400?
So can the m6 use a bit more rear gear with the turbos?
I want my car to be driveable with my clutch and my car is heavy thought the 3.73 would help there too. I expect to have to run et street radials to have any traction on the street anyway. Know my nittos won't work very well with the power plans I have but realistically only going to run 500 to 600rwhp for daily driving.
Can someone point me to the chart thing for gears or calculate for my m6 with 3.54 and 3.73 what I would get for top in 5th and in 4th at a few different rpms. say 6600,6800,7000.
I will have good springs have 918s in there now but likely have dual springs with new heads.
Is it mostly traction reasons to not go 3.73 with the turbos?
So can the m6 use a bit more rear gear with the turbos?
I want my car to be driveable with my clutch and my car is heavy thought the 3.73 would help there too. I expect to have to run et street radials to have any traction on the street anyway. Know my nittos won't work very well with the power plans I have but realistically only going to run 500 to 600rwhp for daily driving.
Can someone point me to the chart thing for gears or calculate for my m6 with 3.54 and 3.73 what I would get for top in 5th and in 4th at a few different rpms. say 6600,6800,7000.
I will have good springs have 918s in there now but likely have dual springs with new heads.
Is it mostly traction reasons to not go 3.73 with the turbos?
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07-08-2007, 02:11 PM
#9
Ok found the perfect site...
http://www.f-body.org/gears/
Exactly for our cars. Crunched the numbers and it looks more than enough for me in quarter without a shift to fifth and top speed.
So really can't see why 3.73 are so bad. Unless in real life it just slows the car too much from not being able to stay in boost as long or something.
So anyone running 3.73 with similar setup on street and are you happy and if not really why not and is traction the only reason? I just never liked 3.42 and going under that in a m6 is just not an option for me. NA I found 3.73 to be the perfect gear.
Also I think can easily put rev limiter at 6800 or 7000 with my springs .Run 6800 no problems at all now. Do higher lsa pull stronger up higher in rpm than lower lsa cams?
http://www.f-body.org/gears/
Exactly for our cars. Crunched the numbers and it looks more than enough for me in quarter without a shift to fifth and top speed.
So really can't see why 3.73 are so bad. Unless in real life it just slows the car too much from not being able to stay in boost as long or something.
So anyone running 3.73 with similar setup on street and are you happy and if not really why not and is traction the only reason? I just never liked 3.42 and going under that in a m6 is just not an option for me. NA I found 3.73 to be the perfect gear.
Also I think can easily put rev limiter at 6800 or 7000 with my springs .Run 6800 no problems at all now. Do higher lsa pull stronger up higher in rpm than lower lsa cams?
07-08-2007, 02:23 PM
#10
Ok no difference in et..so any difference in spool time or whatever must be imagined?
Good of course see gears hurting if you had to shift to fifth at track.
Also my car is mostly city so think more gear would be better and its heavy pig so again maybe better and its m6 have two overdrives up top. If was doing mostly highway than might lean to staying with the 3.42 or 3.54 or even lower. I do likely 90% city and mabye do 10% highway stuff.
Mileage means zip to mean. This is not my daily driver. Traction well as said not afraid to run et street radials almost all the time. Car gets mabye 5000 miles a year on it anyway.
Good of course see gears hurting if you had to shift to fifth at track.
Also my car is mostly city so think more gear would be better and its heavy pig so again maybe better and its m6 have two overdrives up top. If was doing mostly highway than might lean to staying with the 3.42 or 3.54 or even lower. I do likely 90% city and mabye do 10% highway stuff.
Mileage means zip to mean. This is not my daily driver. Traction well as said not afraid to run et street radials almost all the time. Car gets mabye 5000 miles a year on it anyway.
07-08-2007, 02:44 PM
#11
Originally Posted by MY99TAWS6
... Traction well as said not afraid to run et street radials almost all the time. .
07-08-2007, 04:25 PM
#12
Well that sounds like fun to me!
I am so bored right now with maybe my 420 engine hp. The nittos pretty much dead hook when its hot out. Its good for leaving the lights and stuff but at same time kind of boring.
Good thing about turbos is you can turn down the boost and some of the better electronic boost controllers let you adjust for gears etc.
Still that said I fully expect my car even on stock motor to be a pretty crazy ride!BRING IT ON! THE SOONER THE BETTER!
I am so bored right now with maybe my 420 engine hp. The nittos pretty much dead hook when its hot out. Its good for leaving the lights and stuff but at same time kind of boring.
Good thing about turbos is you can turn down the boost and some of the better electronic boost controllers let you adjust for gears etc.
Still that said I fully expect my car even on stock motor to be a pretty crazy ride!BRING IT ON! THE SOONER THE BETTER!
07-08-2007, 04:53 PM
#13
Hmmm.. .
1320 said to use something in the 2.75 - 3.25 range.
I said to use something in the 2.73 - 3.00 range.
cablebandit said the 3.23's are better.
zombie didn't post, but he's using 2.75's in his turbo car.
So you're conclusion is that the 3.73's are the way to go. I think you had your mind made up before you even posted.
Mike
1320 said to use something in the 2.75 - 3.25 range.
I said to use something in the 2.73 - 3.00 range.
cablebandit said the 3.23's are better.
zombie didn't post, but he's using 2.75's in his turbo car.
So you're conclusion is that the 3.73's are the way to go. I think you had your mind made up before you even posted.
Mike
07-08-2007, 05:03 PM
#14
Well..I do like 3.73 NA.. a lot . and liked 4.10 too.
But whining forced me back to 3.42s.
Now some of the above cars are autos. I am an m6 and might stay m6 not sure yet.
Also one poster said his et were identical. Just that the 3.23 was bit better on the hgihway and that could have been subjective. Now I am not a mainly highway car and certainly not a track car. No cage going in ever. Simply a street car. So if the et is same from 3.23 to 3.73 then really should be fine with them , aside from traction issues. And fuel mileage as said not an issue or revving the engine higher. I see from the charts on an m6 that still have lots of mph capabilty in 4th especially if raise the limiter to 6800 to 7000. And lots of mph in 5th with either the 3.73 or 3.54 gears.
Now could put the numbers with autos and it could be very different. Guess punch some of those in and see what I get.Obviously autos don't have the double overdrives the m6 does.
I just think that in a heavy car the gears will help get it moving off the lights and help my clutch be more driveable.
But whining forced me back to 3.42s.
Now some of the above cars are autos. I am an m6 and might stay m6 not sure yet.
Also one poster said his et were identical. Just that the 3.23 was bit better on the hgihway and that could have been subjective. Now I am not a mainly highway car and certainly not a track car. No cage going in ever. Simply a street car. So if the et is same from 3.23 to 3.73 then really should be fine with them , aside from traction issues. And fuel mileage as said not an issue or revving the engine higher. I see from the charts on an m6 that still have lots of mph capabilty in 4th especially if raise the limiter to 6800 to 7000. And lots of mph in 5th with either the 3.73 or 3.54 gears.
Now could put the numbers with autos and it could be very different. Guess punch some of those in and see what I get.Obviously autos don't have the double overdrives the m6 does.
I just think that in a heavy car the gears will help get it moving off the lights and help my clutch be more driveable.
07-08-2007, 05:10 PM
#16
Ok punched in the a4 stuff. So I guess questions there is will the a4s pull higher in od to get a higher top speed than what the charts show in third for max mph?
in the m6 you can get 5th top speed but no so good in sixth maybe with 4.10s in there to pull in 6th not sure.
And again you might need a cam that can pull and springs to let you raise the rev limiter up to say 6800 or 7000.
Now question again can my gt7 with like 121 lsa rev to 7000 if springs are capable of it?
in the m6 you can get 5th top speed but no so good in sixth maybe with 4.10s in there to pull in 6th not sure.
And again you might need a cam that can pull and springs to let you raise the rev limiter up to say 6800 or 7000.
Now question again can my gt7 with like 121 lsa rev to 7000 if springs are capable of it?
07-08-2007, 05:14 PM
#17
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Originally Posted by Armageddon
I ran 3.73s and an M6 in my turbo car. It was fun on the street. I didn't have too much trouble with traction either... I had the tires loaded up pretty well before the car hit full output.
07-08-2007, 05:32 PM
#18
I have 3:73's going to 3:08's I ran out of gear at the track (In 4th) and it hits real hard on the street so I am going to try and tame it alittle with a taller gear I would op for the 3:42 in your spot cause you already have them and go from there it will be a totally different ball game with the FI stuff.
07-08-2007, 05:39 PM
#19
Your're completely correct. My point is simply, the car was able to load the tires up like they needed to be. There was obviously some thought put into the suspension but overall it was extremely driveable. Drag radials hooked fine on the track with a common respect for the throttle.
07-08-2007, 05:41 PM
#20
Inspector your cars are nuts. 
I won't be at your power level much at all. It will be more a potential power output level for me.
So what was your redline. What speeds were you hitting you were running out of gear and again that was track. Not into those speeds on the street.Don't like jail!
From what I see I can make 3.54 or 3.73 work fine especially if go to 6800 say for redline. And the one poster said his et was same. So the downside seems to be pychological. The lower gears feel faster but maybe in reality aren't.
Just shifting the powerband around.
I won't be at your power level much at all. It will be more a potential power output level for me. So what was your redline. What speeds were you hitting you were running out of gear and again that was track. Not into those speeds on the street.Don't like jail!
From what I see I can make 3.54 or 3.73 work fine especially if go to 6800 say for redline. And the one poster said his et was same. So the downside seems to be pychological. The lower gears feel faster but maybe in reality aren't.
Just shifting the powerband around.