Isuzu SUV Forum banner
1 - 15 of 15 Posts

·
Registered
Joined
·
6,257 Posts
that all depends on the kind of driving you're doing. Are you just going for gas mileage, keeping a good rpm and constant speed or are you about to floor it? Obvious one will give you hick ups while the other picks up and goes. Plus a lot of it is personal taste. At what point does it feel natural for you to shift? Forget shift points.
 

·
Registered
Joined
·
4,646 Posts
to be honest i use either 1 of 2 things. either my ear and the rpms or the U/S light.
 

·
Registered
Joined
·
10,560 Posts
Simple if the engine is lugging the gear is too high. If the engine is screaming the gear is too low. The idea is to stay in the comfortable power band of the engine most times. For fuel economy stay in as high a gear as you can without lugging the engine. Need more power down shift. The best way to learn to drive your stick is to install a vacuum gauge in the dash. This will tell you exactly how hard you are working the engine. Vacuum gauge is also the best way to judge driving for fuel economy.
 

·
Registered
Joined
·
5,980 Posts
Discussion Starter · #10 ·
squatch said:
Simple if the engine is lugging the gear is too high. If the engine is screaming the gear is too low. The idea is to stay in the comfortable power band of the engine most times. For fuel economy stay in as high a gear as you can without lugging the engine. Need more power down shift. The best way to learn to drive your stick is to install a vacuum gauge in the dash. This will tell you exactly how hard you are working the engine. Vacuum gauge is also the best way to judge driving for fuel economy.
Ok this is what I was referring too. When driving around the city around 40-45 mph I am wondering if if would be more EFFICIENT to just stay in 4th instead of 5th. I always thought it was bad for an engine to cruise at lower RPM's then it was intended too. Thanks for all the non smart *** replies.
 

·
Registered
Joined
·
934 Posts
jwood1016 said:
squatch said:
Simple if the engine is lugging the gear is too high. If the engine is screaming the gear is too low. The idea is to stay in the comfortable power band of the engine most times. For fuel economy stay in as high a gear as you can without lugging the engine. Need more power down shift. The best way to learn to drive your stick is to install a vacuum gauge in the dash. This will tell you exactly how hard you are working the engine. Vacuum gauge is also the best way to judge driving for fuel economy.
Ok this is what I was referring too. When driving around the city around 40-45 mph I am wondering if if would be more EFFICIENT to just stay in 4th instead of 5th. I always thought it was bad for an engine to cruise at lower RPM's then it was intended too. Thanks for all the non smart a-- replies.
I would say 4th, because 5th might lug the engine. if you're just cruising, I'd try to keep the rpm's around 2k-2500.
 

·
Registered
Joined
·
2,785 Posts
for any auto im in on hills.
when in any gear and holding speed and go to WOT, and gane little speed, its time to down shift.

point is, if you can down shift and reduce throttle use on a hill drastically, its worth it.

not that it applys to your ride in the same way, but the old Isuzu MSGs in the 2WD 81/85 pups are known for getting torn up running at 35mph in 5th. they also have a 3.73 rear and max torque at a low 2,200rpm.
 

·
Registered
Joined
·
5,223 Posts
jwood1016 said:
squatch said:
Simple if the engine is lugging the gear is too high. If the engine is screaming the gear is too low. The idea is to stay in the comfortable power band of the engine most times. For fuel economy stay in as high a gear as you can without lugging the engine. Need more power down shift. The best way to learn to drive your stick is to install a vacuum gauge in the dash. This will tell you exactly how hard you are working the engine. Vacuum gauge is also the best way to judge driving for fuel economy.
Ok this is what I was referring too. When driving around the city around 40-45 mph I am wondering if if would be more EFFICIENT to just stay in 4th instead of 5th. I always thought it was bad for an engine to cruise at lower RPM's then it was intended too. Thanks for all the non smart a-- replies.
JOHN DO WHAT MARK SAID , GET YOU A VACC GAUGE AND SET IT WHERE YOU CAN SEE IT AND RIVE BY WHAT IT IS TELLING YOU , IT WILL BASICALLY TELL YOU WHAT YOUR THROTTLE OPENING IS AT ANY SPEED OR GEAR POSITION, AND YOU WANT TO DRIVE AT THE HIGHEST VACC READING YOU CAN FOR THE MOST MPG, IN OTHER WORDS AT 45 MPH JUST SAY YOU ARE READIGN 14 IN VACC , IN 5TH GEAR MAINTAIN THAT SPEED AND GO TO 4 RTH G GEAR IF THE MANIFOLD VACC INCREASE TO 18 IN OR GOES UP ANY YOU NEED TO BE IN THAT GEAR AT THAT SPEED , ANY TIME YOU SHIFT TO A HIGHER GEAR AND THE MANIFOLD VACC DROPS THE ENG IS WORKING HARDER THE ROM AT THE HI MANIFOLD VACC HAS LITTLE TO DO WITH FUEL MILEAGE , SINCE THE HIGHER THE READING THE MORE CLOSED THE THROTTLE BLADES ARE WHICH MEANS LESS AIR IN THE ENG AND LESS FUEL, I PROMISE YOU ,YOU WILL CHANGE YOU DRIVING HABITS WITH THE VACC GAUGE
 

·
Registered
Joined
·
1,796 Posts
or get an scangauge II, it tells you so many things including air fuel ratio, fuel usage, fuel economy, obd 2 scanner and list goes on and on.... and they go for about $150
 

·
Registered
Joined
·
141 Posts
After running my own DYNO for years I learned quite a bit.. Although everything I did was with Bikes I would suspect much of it still applies to cars/trucks as well..

Generally speaking an engines H/P & Torque curve will cross at 5250 RPM.
With that in mind how you drive determines the best way to use your engine. I'm not sure where PEAK Torque is made in an ISUZU V 6 for example but I'm gonna guess somewhere around 3500 RPM. Normally speaking (there are exceptions) a specific cam has it's best performance designed around a 3000 RPM range.

Having said that here is what I always told my customers, H/P "Accelerates" , "TORQUE" Motivates..

"IF" your intention is to drive around town and use the engines power best that will happen within that 3000 RPM cam range and around the engines PEAK torque RPM. The engine will be happy in say that 1500-4500 RPM range and will prolly run the best and be most efficient shifting @ or close to 3K RPM.
This is how I've taught my Son to drive his 5-spd RODEO, shifting around 3K and NOT lugging the engine in the taller gears.. To me it's pretty obvious what is the correct gear by using my ear and the TACH as reference & I'm sure I'm not alone. Having driven manual shift cars & trucks as well as Bikes all my life it's a no brainer..

Now "IF" a little STOP light to STOP light race is imminent, or ifya find yourself at the strip then run the TACH up and shift when the motor quits pulling (making power).. Having never seen a DYNO run with any of these motors I'm going to guess PEAK H/P prolly happens around 5K..
 
1 - 15 of 15 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top