Forced Induction - turbo spooling.. differnce between manual and auto?

i havent driven a turbo car other then a Jetta, and that was an auto.
I am curious as to the difference between the way the turbo's spool and perform with the different tranny (manual and auto).

in my case, it is a GTO. does the turbo stay in boost easier with one or the other??
can someone tell me the differences?

Manual cars have trouble building boost off the line. They need a thing called a two step ,sometimes called a stutterbox. This lets you hold the gas down and build boost at the line. For my imports you can use something called antilag.Haven't seen that option on our f bodies dont' think.
Manuals don't hold the boost as well between shifts. You can powershift ,keep your foot to the floor to help this out and ball bearing turbos generally stay spooled up better and recover quicker.You can downshift in manuals to get quicker spool up.Of course this don't work going up thru the gears which is when you need the two step or antilag.

Autos will generally build boost quick and quite a bit of it ,depending on stall converter. They will keep boost up between shifts. Autos give a bit more driveline loss than manuals..usually estimated at about 5 per cent diff in our cars.

Manual cars have trouble building boost off the line. They need a thing called a two step ,sometimes called a stutterbox. This lets you hold the gas down and build boost at the line. For my imports you can use something called antilag.Haven't seen that option on our f bodies dont' think.
Manuals don't hold the boost as well between shifts. You can powershift ,keep your foot to the floor to help this out and ball bearing turbos generally stay spooled up better and recover quicker.You can downshift in manuals to get quicker spool up.Of course this don't work going up thru the gears which is when you need the two step or antilag.

Autos will generally build boost quick and quite a bit of it ,depending on stall converter. They will keep boost up between shifts. Autos give a bit more driveline loss than manuals..usually estimated at about 5 per cent diff in our cars.
Hp for HP.....the auto will own the manual every time. Instant spool in any gear, and a trans brake for the line.

so a turbo on a manual isnt the best idea? a supercharger may be a better idea huh

Manuals work fine for turbos,unless you are worried about a pure drag race car. Two steps are 250 bucks from lingenfelter but you can't use cats with it. And you can downshift to get boost faster in a manual. And once the manual is spooled up it does just fine.
So do not fear a manual with a turbo. And even with a super a good stall is necessary. Buddy had an ati car with a stock stall and it was a big dog off the line.

automatics are good cause u can build boost off the line. just brake torque it. my gsx would build about 6-7 psi b4 i would launch

what is a two step, and how does it work?

thanks for the help all.

It lets you floor the car and hold it at a certain rpm like 5000. As you hold it there the turbo will start to build boost. Then you launch and your normal rev limit is there for shifting your gears.

It lets you floor the car and hold it at a certain rpm like 5000. As you hold it there the turbo will start to build boost. Then you launch and your normal rev limit is there for shifting your gears.

They pull timming usually so the car will only rev to a set amount. Making the car stutter, or stay @ that rpm. It Acts as if the car is floored @ that rpm, and the rpm's being up make the turbo spool up giving you boost.

The lpe one is pretty nice, and the easiest to install for sure.

A manual is a manual. A turbo manual will still be bad ass, and a manual Supercharger will still be manual. Auto's are better for drag racing, they can leave harder off the line, and no one can shift as fast as an auto. Manuals are fun :).

Chris

of coure auto's are supreme for drag racing. In all honesty, i never had a manual before this so it just seemed more fun when i got it. I still love it, but i would have went auto if i knew then what i knew now (famous last words).

thanks alot fellas. much appreciated.

Lets see an auto make use of full boost at 2-3000rpm for lazy overtaking in a high gear though.

just doesnt happen with an auto that always wants to kickdown and rev the engine.

Autos by nature would be slower to build boost, as they dont load the engine as hard. Most dynos will highlight that.

Turbochargers and manuals work very well. Its just you guys in the US love your autos so much. It isnt the same in most other parts of the world.

But for straight line racing, then an auto will usually always win. You wont see any turbocharged automatic circuit cars, or rally cars though, or any form of racing that involves corners.

I can't believe there are several people in this thread that think manuals spool faster than an auto. I've had both....no way in hell an M6 will EVER spool like an auto.....or keep up in a straight line. The only time I see a 6 speed having an advantage is in the twistys.

I concede the advantage to the auto off the line for buidling boost and you cant misshift too easily unless you are shifting manually maybe but in my experience on my dsm cars the autos run quite a bit slow than the manuals in stock form.And the manuals trap higher also.

I can't believe there are several people in this thread that think manuals spool faster than an auto. I've had both....no way in hell an M6 will EVER spool like an auto.....or keep up in a straight line. The only time I see a 6 speed having an advantage is in the twistys.

The only reason a auto might appear to spool faster, is because it always kicks down, revs its nuts off.

You cannot use full throttle in a highish gear on an auto car, to see how it actually spools. You can in a manual.

So other factors come into it with an auto. Not everyone drives their car revving the crap out of it.
But yes, and auto will be faster in a straight line. Nobody denies that. Not everyone restricts themselves to travelling in straight lines though.


Put both on a dyno, go WOT at say 1500rpm in 4th gear. And see which achieves max boost first ?

Or cant an auto do that ?

The only reason a auto might appear to spool faster, is because it always kicks down, revs its nuts off.

You cannot use full throttle in a highish gear on an auto car, to see how it actually spools. You can in a manual.

So other factors come into it with an auto. Not everyone drives their car revving the crap out of it.
But yes, and auto will be faster in a straight line. Nobody denies that. Not everyone restricts themselves to travelling in straight lines though.


Put both on a dyno, go WOT at say 1500rpm in 4th gear. And see which achieves max boost first ?

Or cant an auto do that ?
Why are we talking about "stock transmissions" on turbo cars? Do these boosted 6 speeds have an oem clutch in them? No. I am talking about stalled RMVB transmissions.....as 99% of turbo cars require upgraded trans componets.

Put an M6 in 4th at 1500rpms, put a stalled TH400 in 3rd at 1500, floor it.........who wins?

Lets see an auto make use of full boost at 2-3000rpm for lazy overtaking in a high gear though.

just doesnt happen with an auto that always wants to kickdown and rev the engine.

Autos by nature would be slower to build boost, as they dont load the engine as hard. Most dynos will highlight that.




WAT


Lol, where did you get your info? It sounds like you haven't driven or even ridden in a real automatic turbo car. In most auto turbo cars the trans is almost always manually shifted and will NOT shift by iteself. I know in my auto car I can put it in 3rd gear at a light and that's the gear it's going to stay in no matter what I do with the gas peddle, there is no kick down.

Automatic transmissions always spool the turbo faster than the same car with a manual trans since an auto loads the engine much harder than a manual trans can. The converter allows slip to occur and the RPMs to go higher at the same speed and boost to build faster, of course once boost builds the stall goes even higher and boost builds even faster than it was before. It's a positive feed back system.

My car was 6spd before i swapped it to a 3spd auto. The spoolup was so much faster I couldn't believe it. I started kicking my self for being a 6spd nut swinger for all those years. It's almost comical to compare the spoolup of a manual car to an auto because the auto spools so much faster.

If you are interested in road racing (every one says they are but very few ever do it) a manual is the trans you want. I personally find my RMVB Th400 with trans brake WAAAAAAY more fun to drive on the street than the 6spd ever was with the turbo.


Put an M6 in 4th at 1500rpms, put a stalled TH400 in 3rd at 1500, floor it.........who wins?

That's funny right there lol. Let's see, i'd be at 40mph @ 1500 rpms in 3rd, boost would be full on by 50mph from that speed if it hooked and I wouldn't ever make another shift and would top out at 180+mph. Hard on the trans due to heat though.

call me weird but manually shifting my 4l80e with the tables set to hold the gear its in worked very well last year. In the twistys too.

True, I have never driven a race car with an auto trans, only a factory one.. Race cars over here have manual gearboxes.

Although lots of drag only cars do of course use autos.

And as for Ninetres mentioning stock transmissions on turbo cars. Who asked about race transmissions ?

I didnt see anyone ask about them.

And as for Ninetres mentioning stock transmissions on turbo cars. Who asked about race transmissions ?

I didnt see anyone ask about them.

Is this thread in the FI section? What stock trans handles 500+rwhp?

The thread starter wanted to know which trans stays in boost better.....and the easy winner of that contest is an auto.

Is this thread in the FI section? What stock trans handles 500+rwhp?

The thread starter wanted to know which trans stays in boost better.....and the easy winner of that contest is an auto.

A bone stock 4l80e will handle 500 rwhp easily.

auto here..... full boost by 3000 rpms. my stock tranny lasted only a week with a turbo. swapping a 4L80e isnt stock either.

food for thought I gained 6 tenths by going to a 4L80 with transbrake leaving just at boost. the M6 suxed for drag racing. unless you roll race.

auto here..... full boost by 3000 rpms. my stock tranny lasted only a week with a turbo. swapping a 4L80e isnt stock either.

lol brutal.

just so people know, i was talking about street cars, a stock gto auto or manual. I have never been to a track, never even seen an automatic transmission manually shifted. I thought that would fuck up the trans? or is it different in race cars?

sorry for my ignorance, but i am new to this game, as is obvious in my posts.

just so people know, i was talking about street cars, a stock gto auto or manual. I have never been to a track, never even seen an automatic transmission manually shifted. I thought that would fuck up the trans? or is it different in race cars?

sorry for my ignorance, but i am new to this game, as is obvious in my posts.

A stock trans will not last with boosted ls1 cars....even with low boost.

Just do what I'd do and make more power. Building boost off of the line isn't as big of a problem if you can make it up on the big end.

Just do what I'd do and make more power. Building boost off of the line isn't as big of a problem if you can make it up on the big end.

What?

A stock trans will not last with boosted ls1 cars....even with low boost.

they will with blown cars..my M6 was fine at 650RWHP in my goat,but common sense and lifes lessons all say the auto will kill the 6 speed.I will however say i have cut some of the same times if not better than most of the auto gto's out there.I do however know i will be looking at a auto for my turbo build and it wont be a stock auto...