Turbo guys?
If you search "boosted list" you can find lots of data on this subject. Seems many guys on there have run very fast with higher gears than most people think are best for turbos. Was quite suprised to find very many very fast cars running 3.73 and 4.10 although there were quite a few running lower gears as well.
Too low a gear nuerically makes a car very doggy off boost so then it depends on where and how quick your turbo spools up. I can't decide between 3.54 and 3.73 personally in planned dana 60.
Too low a gear nuerically makes a car very doggy off boost so then it depends on where and how quick your turbo spools up. I can't decide between 3.54 and 3.73 personally in planned dana 60.
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Gearing has nothing to do with the type of forced induction or the ET. You gear a car to hit max rpm as you pass through the traps. It just so happens that turbo v-8's make a lot of power at a low rpm, and trap very high speeds. So, they need tall gears. I'm going 146 mph at 6200 rpm (my max rpm) using a 3.00 gear and 26" tire.
Hmm most turbo guys say the load from the lower numerical gears helps the car make boost faster. Still really low numerical gears are pretty annoying off boost . I generally like around a 3.42 for around town snap in an auto and love 3.73 in the m6.
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The energy is a function of temperature. EGT is the same at low rpm and high rpm, so the gear doesn't affect it.
Mass flow is a function of rpm and throttle angle. You get more mass flow at higher rpm. So, the sooner you can get an engine to a high rpm, the more mass flow you're going to supply to the turbo, the quicker it will spool up. I used to have a sloppy-loose torque converter in my car. The turbo spooled up really quick because the converter allowed the engine to reach 4000 rpm as soon as you hit it. Of course, with boost it would blow right through it, but that's a topic for another day. . .
Taller gears may SEEM like you get boost sooner, but it's only because you get it at an earlier rpm, not in less time. Heck, if you have a 6-spd and start out in 6th gear, you might get boost at 2000 rpm, but you're better off starting off in 1st and not getting boost until 4000 rpm. I assure you 4000 rpm in 1st will come sooner than 2000 in 6th.
Last edited by engineermike; Sep 11, 2008 at 01:25 AM.
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It looks 3.5 and lower number is what most of the turbo guys are running.
I run a 3.73 and a 30" tire.. Was on a 28" tire but needed a little more to get it out the back door in the power.
Being rear mount my spool suffers a little but I noticed no difference in spool when changing froma 28" to 30" tire. Full boost of 13psi by 4000rpm in first gear.
Being rear mount my spool suffers a little but I noticed no difference in spool when changing froma 28" to 30" tire. Full boost of 13psi by 4000rpm in first gear.
great info guys i really appreciate it.Im a turbo newb with a fairly badass setup,but since i just got it in i need alot of work to get to where im going.....
if it was'nt for this damn site and the fast guys i would still have my maggie and still be in the 10's.....Now im back at baby steps running 15 seconds my first run out,so sorry for the stupid questions but thats how im gonna learn.
if it was'nt for this damn site and the fast guys i would still have my maggie and still be in the 10's.....Now im back at baby steps running 15 seconds my first run out,so sorry for the stupid questions but thats how im gonna learn.
great info guys i really appreciate it.Im a turbo newb with a fairly badass setup,but since i just got it in i need alot of work to get to where im going.....
if it was'nt for this damn site and the fast guys i would still have my maggie and still be in the 10's.....Now im back at baby steps running 15 seconds my first run out,so sorry for the stupid questions but thats how im gonna learn.
if it was'nt for this damn site and the fast guys i would still have my maggie and still be in the 10's.....Now im back at baby steps running 15 seconds my first run out,so sorry for the stupid questions but thats how im gonna learn.
I'm hoping for a mid-10 slip at the Mustang/GTO meet on stock gears.
yeah i did,my car has no power and im retarded,so i guess they balanced out to a 15...lolI think there is alot of street tuning that needs to happen.We tuned the car on the dyno just to get it out on the track.This setup has 0 miles on the motor and only a few dyno pulls and i took it out....To say the least i was embarrassed
