id like to knwo how this motor produces boost? im planning on swapping it into my firbird and im equipped with a t56. most are telling me to dump it and go with a auto. the reason im being told the most is the abilty to build boost with a torque converter as opposed to with out one. could anyone tell me why i cant use a t56 and what produces the boost or how the motor senses load to produce the boost.
how does this motor produce boost?
- Thread starter 93formula
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pat83t
Guest
go with an hks blow off valve and it will keep the boost from dropping off to much while shifting
I'll try and explain this the best I can............
The torque converter slips against the motor causing a load. When you are driving up a steep hill it takes more effort for the motor to maintain your current speed right? Thats because the hill is putting a load on the motor kind of like the converter does. The motor is forced to work harder thus producing more exhaust gasses that the turbo runs off of and it does so at a much lower rpm than you possibly could with a manual tranny. I know all about two step rev limiters that some manual turbo cars use but that is only applicable on launch and even then its not as effective as an auto because the boost falls back to zero when you shift. With an automatic, the converter is always slipping somewhat which maintains the load and gives you constant boost until you let off the gas. These motors do not rev high at all. If you hook up a manual tranny to one of these motors it wont even build any boost until you are damn close to redline and at that point you will have to shift and the boost will drop all the way back to zero. You will only be in boost for a split second until you are forced to shift and until then you have a car with a good bit less horsepower than a Honda Civic that weighs 3600 lbs. If you are dead set on a manual tranny then you should stick with the LT1 or get a Supra or RX7 with a manual. Turbobuicks are not in the same boat as these other cars because they make their power significantly lower in the rpm band. Thats why turbobuicks are referred to by many as one of the best quarter mile vehicles to ever come out of Detroit. Torque rules the dragstrip and thats one reason why turbobuicks are great dragracers, because they produce ungodly amounts of torque.
To sum it up:
Auto trannies use load to make the engine produce boost lower in the rpm band in which it was DESIGNED for whereas manuals rely on engine rpm to build boost and RPM's is not what these motors were DESIGNED for. The turbo wastegate dictates whether your exhaust gasses will be used to create boost or just routed out your exhaust through the downpipe, but that is a whole other explanation.
I can elaborate plenty more if this doesn't help......
I recommend reading on www.gnttype.org about turbo theory if you are confused about some of the aspects of a turbo car.
The torque converter slips against the motor causing a load. When you are driving up a steep hill it takes more effort for the motor to maintain your current speed right? Thats because the hill is putting a load on the motor kind of like the converter does. The motor is forced to work harder thus producing more exhaust gasses that the turbo runs off of and it does so at a much lower rpm than you possibly could with a manual tranny. I know all about two step rev limiters that some manual turbo cars use but that is only applicable on launch and even then its not as effective as an auto because the boost falls back to zero when you shift. With an automatic, the converter is always slipping somewhat which maintains the load and gives you constant boost until you let off the gas. These motors do not rev high at all. If you hook up a manual tranny to one of these motors it wont even build any boost until you are damn close to redline and at that point you will have to shift and the boost will drop all the way back to zero. You will only be in boost for a split second until you are forced to shift and until then you have a car with a good bit less horsepower than a Honda Civic that weighs 3600 lbs. If you are dead set on a manual tranny then you should stick with the LT1 or get a Supra or RX7 with a manual. Turbobuicks are not in the same boat as these other cars because they make their power significantly lower in the rpm band. Thats why turbobuicks are referred to by many as one of the best quarter mile vehicles to ever come out of Detroit. Torque rules the dragstrip and thats one reason why turbobuicks are great dragracers, because they produce ungodly amounts of torque.
To sum it up:
Auto trannies use load to make the engine produce boost lower in the rpm band in which it was DESIGNED for whereas manuals rely on engine rpm to build boost and RPM's is not what these motors were DESIGNED for. The turbo wastegate dictates whether your exhaust gasses will be used to create boost or just routed out your exhaust through the downpipe, but that is a whole other explanation.
I can elaborate plenty more if this doesn't help......
I recommend reading on www.gnttype.org about turbo theory if you are confused about some of the aspects of a turbo car.
okay so i realize that the auto is gonna be waaay faster. i can always leave off the line with the current nitrous set up i have in my car. now if the wastgate dictates weather the gasses are routed to the turbo or not, isnt there a way to dictate the wastegate to dump the exhaust into the turbo earlier?
how long does it take to build the boost? the only turbo experience i have is with my chrysler laser i owned which was a 5 speed. the turbo spooled damn fast in that car and when i did shift gears the boost did drop to zero but the instant i steped on the gas and was in gear the boost was back at the peak, i didnt have to build it back up again. maybe thats why im cunfused here as to why i shouldnt use manual.
how is cruising around in the city with these cars? im sure your not always using boost, and if you were to land on it does it take long for the turbo to spool to its peak psi? again the only experience i had was stated above and if i just landed on the throttle the turbo would spool to peak in fractions of a second. the rest of the time the turbo would spool but the needle would hover around 1 psi or below.
i thank you for your input
how long does it take to build the boost? the only turbo experience i have is with my chrysler laser i owned which was a 5 speed. the turbo spooled damn fast in that car and when i did shift gears the boost did drop to zero but the instant i steped on the gas and was in gear the boost was back at the peak, i didnt have to build it back up again. maybe thats why im cunfused here as to why i shouldnt use manual.
how is cruising around in the city with these cars? im sure your not always using boost, and if you were to land on it does it take long for the turbo to spool to its peak psi? again the only experience i had was stated above and if i just landed on the throttle the turbo would spool to peak in fractions of a second. the rest of the time the turbo would spool but the needle would hover around 1 psi or below.
i thank you for your input
you seem to be missing the main point that has been made several times.....the engine must be loaded to make boost...that is, it must be in gear and clutch engaged (in the case of a manual) or loaded against the torque converter (auto)
the wastegate has nothing to do with boost until you make some.....it only opens when the boost exceeds a certain point
reference to a 4 cyl, low boost motor has nothing to do with a TR.....of course the boost will reappear when the clutch is engaged, because the engine is then under load and the rpm is up, thus generating exhaust gasses sufficient to spin the turbo
if you want to put a manual behind a 3.8 turbo, then by all means do so...just recognize you are being advised against it by those of us that maybe know a bit more about turbo cars than you....
the wastegate has nothing to do with boost until you make some.....it only opens when the boost exceeds a certain point
reference to a 4 cyl, low boost motor has nothing to do with a TR.....of course the boost will reappear when the clutch is engaged, because the engine is then under load and the rpm is up, thus generating exhaust gasses sufficient to spin the turbo
if you want to put a manual behind a 3.8 turbo, then by all means do so...just recognize you are being advised against it by those of us that maybe know a bit more about turbo cars than you....
Boost is a measurement of manifold pressure. Boost goes to zero when the throttle is closed becuase the motor swallows all the air in the manifold. If you shifted a turbo car with your foot flat on the floor, boost would not go to zero on shifts. You'd also likely over rev and blow up your car.
With a stock turbo and stock converter car at idle, if you floor the car you can count 1,2 and the turbo will spool. Once a turbo spools it heads straight for max boost as fast as the needle can swing. By power braking a car against the converter, you can get to the spool point and still be standing still. When you release the brakes you leave with almost instantanious power (zero lag).
This is very hard to do on a manual car. The torque converter allows an automatic car to store energy before launch, while the manual cannot without smoking the clutch or using some type of electronic rev limiter which come nowhere near "storing" the amount of power a converter can.
As far as cruising around goes, the higher the RPM you are running, the closer you are to instantanious boost. At 65 mph on the highway if you toe it enough to down shift into drive, boost will be right there. If it doesn't downshift or the converter stays locked, it will be lagging until the turbo spools.
The idea of using nitrous as a way to get the turbo to spool quicker with a manual is silly. Suffice to say the first weekend you get it to work you will break your rear end in two, if you don't smoke the clutch first. You aren't the first person to have tried this, Some have spent 10's of thousands of dollars trying to make it work. It's kind of funny how out of the 40K+ turbo regals built and the hundreds of shows, magazine articles, etc, you never see any successful manual trans, stock 3.8 Block powered cars.
Kinda makes you stop and think, doesn't it?
With a stock turbo and stock converter car at idle, if you floor the car you can count 1,2 and the turbo will spool. Once a turbo spools it heads straight for max boost as fast as the needle can swing. By power braking a car against the converter, you can get to the spool point and still be standing still. When you release the brakes you leave with almost instantanious power (zero lag).
This is very hard to do on a manual car. The torque converter allows an automatic car to store energy before launch, while the manual cannot without smoking the clutch or using some type of electronic rev limiter which come nowhere near "storing" the amount of power a converter can.
As far as cruising around goes, the higher the RPM you are running, the closer you are to instantanious boost. At 65 mph on the highway if you toe it enough to down shift into drive, boost will be right there. If it doesn't downshift or the converter stays locked, it will be lagging until the turbo spools.
The idea of using nitrous as a way to get the turbo to spool quicker with a manual is silly. Suffice to say the first weekend you get it to work you will break your rear end in two, if you don't smoke the clutch first. You aren't the first person to have tried this, Some have spent 10's of thousands of dollars trying to make it work. It's kind of funny how out of the 40K+ turbo regals built and the hundreds of shows, magazine articles, etc, you never see any successful manual trans, stock 3.8 Block powered cars.
Kinda makes you stop and think, doesn't it?
all very good points. so if i were cruising around and landed on the throttle then there would be minimal turbo lag right? thats my main concern with sticking with manual. the quarter mile times im not too worried bout.
why would it be silly to use nitrous to launch? wouldnt that give me sufficeint power to launch while the turbo spools?
how much slower are we talking about here? say a 11 sec auto car will equal a 12 sec manual?
again many thanks to those who are bearing with my ignorance
why would it be silly to use nitrous to launch? wouldnt that give me sufficeint power to launch while the turbo spools?
how much slower are we talking about here? say a 11 sec auto car will equal a 12 sec manual?
again many thanks to those who are bearing with my ignorance
I beginning to think you may just be playing us. How many different people have to tell you the same thing before you will listen? There is a lot of combined knowledge here, and people willing to share it. Beware, patience amongst those is short!
The horse is dead! Quit beating on it.
Paul
The horse is dead! Quit beating on it.
Paul
dude im not playing you, cant you tell by the many questions i have??? i just wanna know how much slower am i gonna be. if you cant answer that for me then please dont get upset. ive come to the realization that i will be considerably slower then a auto equipped car, im not trying to make up excuses for it anymore. just how much of a diff is it?
Not only will you be slower but you'll have a lot of broken pieces to show for it. lets list them, shall we:
T56 - 93 T56's are weak. so long first gear. Got $2700 for a richmond?
Clutch - Fbody clutches are tiny and suck. So long clutch.
Rear end. Fbody rear ends are made of glass. So long rear end.
Miss a shift with a stock block 3.8? hello spun bearing.
Overrev a stock block 3.8? hello broken crank.
This could all conceivably happen in the first week of operation, IF you were made of money and could fix the broken parts quick enough. Otherwise, it will sit in the garage most of its life while people who KNOW what they are talking about ask you "why don't you just put an automatic in it?" and people with no clue tell you "I bet its FAST!"
T56 - 93 T56's are weak. so long first gear. Got $2700 for a richmond?
Clutch - Fbody clutches are tiny and suck. So long clutch.
Rear end. Fbody rear ends are made of glass. So long rear end.
Miss a shift with a stock block 3.8? hello spun bearing.
Overrev a stock block 3.8? hello broken crank.
This could all conceivably happen in the first week of operation, IF you were made of money and could fix the broken parts quick enough. Otherwise, it will sit in the garage most of its life while people who KNOW what they are talking about ask you "why don't you just put an automatic in it?" and people with no clue tell you "I bet its FAST!"
Red Regal T
Senior Member
- Joined
- May 24, 2001
SOME PEOPLE HAVE TO BE SHIFTERS NO MATTER WHAT THE DISADVANTAGES.
T
TTA89
Guest
Why dont you stick with the LT1 and then keep your T56. For what its going to cost you in time and money to find all the right parts you can build a nice 10 or 11 second motor.
If you want a stick, just stay with the V8. The learning curve of these motors is going to take you awhile to learn, and its obvious you dont want to
If you want a stick, just stay with the V8. The learning curve of these motors is going to take you awhile to learn, and its obvious you dont want to
REDS HOT AIR
Buick Tweaker
- Joined
- May 24, 2001
i can solve all you auto tranny questions at one time...get the correct BRF code 2004r tranny and call Bruce (we4) for a shift kit and a 9-11 converter if you got the extra funds and tranny is ready.
Turbo-Rich
ALBATROSS
- Joined
- May 25, 2001
WOW, I was always under the impression that Horsepower ruled the dragstrip & Torque ruled the STREETS
Where have I been
It's not that you can't make boost with a manual, it's that you can't make boost before you launch like you can with an automatic. After the clutch is out and the car is moving the boost will come up just like it would with the automatic with a really tight torque converter if you just stomped the gas from idle. Depending on the engine tuning (rich, lean, timing) and the turbo itself, plus the exhaust system, it will take some time for the turbo to get up to speed. During that period the wastegate will be fully closed. Once the turbo is up to speed it can usually move more air than needed, so the wastegate opens to bypass some of the exhaust around the turbo to maintain a constant boost pressure. For drag racing purposes, you can use a two-step box with a manual (or automatic trans with a brake) which will retard the timing to raise the egt and which will drop ignition pulses to maintain a constant rpm while you keep your foot on the floor. That lets you make boost while sitting still on the line, but is basically useless any other time. With an automatic, when you hit it from idle the engine will go up to the stall speed and then hold there as the vehicle speed rises and the converter slips less and less. At some point the rpms will rise again as the vehicle speed/gearing lets the motor rpms rise above the stall speed. That process lets the motor very quickly get to an rpm where it is making much more torque and moving much more air than the manual car with the clutch out and just above idle, so the turbo will spool quicker with the automatic. That happens any time you hit it, not just when you have stopped, engaged the twostep, and built boost, so in terms of red-light to red-light street performance the automatic wins. After the boost is up in first gear both are similar except the flywheel is lighter with the manual so the engine can rev quicker, but on the shift the boost will drop with the manual while the auto maintains the load against the engine and the engine stays at wot so the boost stays up (and you don't have to be a great shifter and you never miss a shift). Again, you can put in a blow-off valve that vents the boost back into the turbo inlet so the turbo will stay spooled during shifts to basically eliminate this problem (you can put it on the auto car as well but it won't help during shifts but will eliminate the compressor sneeze when you let off; a good thing on either setup). For drag racing these cars the automatic seems better. One of the car magazines did a test many years ago where they took a Grand National and put in a 5 speed manual - they made a 13 sec car into a 15 sec car in the quarter. For roadracing the manual is probably better, if you put in the blow off valve. For around town driving and short-notice passing situations (ok, for impromptu street racing ), the auto has the edge. The vast majority of people here are into drag racing so we all think the auto is king. There is a guy on the gnttype list (antong, I think) who roadraces a Corvette with a stage 2 motor and 5 or 6 speed, so at least one guy is happy with that combination.
), the auto has the edge. The vast majority of people here are into drag racing so we all think the auto is king. There is a guy on the gnttype list (antong, I think) who roadraces a Corvette with a stage 2 motor and 5 or 6 speed, so at least one guy is happy with that combination.wow thanks for the info. now im thinking again, hmmm. ill try and track down the vette guy and see how he likes it.thank you so much everyone for all your info and time, right now the auto is still prolly ahead in my choice till i do more research on the manual.
thanks for the info. now im thinking again, hmmm. ill try and track down the vette guy and see how he likes it.thank you so much everyone for all your info and time, right now the auto is still prolly ahead in my choice till i do more research on the manual.The "vette guy" mentioned has a Stage II motor. Night and day between that and a stock block 3.8L in price and performance. A stage II has a block and crank that will rev above 5600 RPM without breaking and heads that flow 300 CFM (vs. 160 in a stock motor) I guarantee he does not have a '93 T56 behind the engine, either.
His drivetrain alone was probably $15K and maybe close to $20K. You got that kind of money? If so go ahead and look him up. Don't get sticker shock when he tells you how much he's spent.
His drivetrain alone was probably $15K and maybe close to $20K. You got that kind of money? If so go ahead and look him up. Don't get sticker shock when he tells you how much he's spent.
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