More torque in the lower revs?
01-07-2001, 09:01 AM
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More torque in the lower revs?
We all know that when we put a sport exhaust on our 1.8t we have more torque in higher revs but lower tq, let's say from 2000 to 4000rpm. I have the following idea. Would it be possible to build a restrictor into the exhaust that opens fully from 4000rpm but stays more close from 2000 to 4000rpm. With that thing we could have both, tq in low and high revs.
What do you think about that?
Ralph
What do you think about that?
Ralph
01-07-2001, 09:56 AM
#2
You are thinking normally aspirated. You already have a restrictor at lower revs -
it is called the turbo. Depending on it's size, it provides enough restriction at low rpms.
The reason for the low power low torque condition on the low rpm side is the low compression ratio engine running at normally aspirated mode of say 100hp trying to move 3200lbs. And the only thing that would help it is to increase it's compression ratio by way of boosting the air earlier.
Hence, here are some ideas I can think off while I waste my time working on a Sunday :P to increase spool up time, and low end torque:
1) High flow exhaust, so turbo can spool up faster without restriction
2) Smaller turbo, smaller than K03, but I would not want to find ut what the top speed is
3) shorten the intake track from turbine output to intake manifold - this includes the I/C, hoses and plenum also. This smaller volume will allow the turbo fill in the volume and pick up boost earlier
4) Increase the CR by piston changes, rod or crank itself. Put some daddy long legs in there, or approach the same configuration as a low end torque motor. Ughh, normally for added boost and reduced detonation due to higher pressures, they usually go the other way around, but this will work with a rinky dink turbo with a max boost of 5 psi :P
5) NOS kit on low rpm only - increase more oxygen - and appropriate fuel content so that the combustion has more energy
6) Ok, time to get back to work, but so many other ways
So what to do? On the TTR the boost lag is very pronounced - because of the really low CR which make the engine have about 135hp until about 2500 rpm when the torque peaks and reaches it's 225 hp mark. Hence the boost, no boost condition is very much felt, but easy to come by with a quick blip of the throttle before engaging the clutch. Makes it fun to drive that way too
The reason for the low power low torque condition on the low rpm side is the low compression ratio engine running at normally aspirated mode of say 100hp trying to move 3200lbs. And the only thing that would help it is to increase it's compression ratio by way of boosting the air earlier.
Hence, here are some ideas I can think off while I waste my time working on a Sunday :P to increase spool up time, and low end torque:
1) High flow exhaust, so turbo can spool up faster without restriction
2) Smaller turbo, smaller than K03, but I would not want to find ut what the top speed is
3) shorten the intake track from turbine output to intake manifold - this includes the I/C, hoses and plenum also. This smaller volume will allow the turbo fill in the volume and pick up boost earlier
4) Increase the CR by piston changes, rod or crank itself. Put some daddy long legs in there, or approach the same configuration as a low end torque motor. Ughh, normally for added boost and reduced detonation due to higher pressures, they usually go the other way around, but this will work with a rinky dink turbo with a max boost of 5 psi :P
5) NOS kit on low rpm only - increase more oxygen - and appropriate fuel content so that the combustion has more energy
6) Ok, time to get back to work, but so many other ways
So what to do? On the TTR the boost lag is very pronounced - because of the really low CR which make the engine have about 135hp until about 2500 rpm when the torque peaks and reaches it's 225 hp mark. Hence the boost, no boost condition is very much felt, but easy to come by with a quick blip of the throttle before engaging the clutch. Makes it fun to drive that way too
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