lame scoob
19 July 2002, 11:21 PM
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Could any one help mw with a problem I encounter a lot on my 96 wagon. It seems very underpowered in the low rev range (under 3000rpm) .When you floor it you just get a loud indution noise, and you have to wait for the revs to slowley creep up and then a sudden surge of power.Have been caught out many times when overtaking .I find I have to Keep the car above the 3000rpm with gearchangers when overtaking. Any Idea's.
19 July 2002, 11:32 PM
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Drop one or two gears and drive around it. The blessings and curse of a largeish "well matched" turbo on a 2 litre low compression engine.
A full exhaust system and boost control or an ECU remap would also help. Some also convert the turbo to straight entry. Shorter ratio gearbox?
Other less realistic options for most include increasing capacity, nitrous, supercharger. Or sell it and buy a six/eight cyl, twin turbo or small turbo vehicle.
Depends on what you want to spend.
[Edited by Torque Monster - 7/19/2002 11:34:35 PM]
A full exhaust system and boost control or an ECU remap would also help. Some also convert the turbo to straight entry. Shorter ratio gearbox?
Other less realistic options for most include increasing capacity, nitrous, supercharger. Or sell it and buy a six/eight cyl, twin turbo or small turbo vehicle.
Depends on what you want to spend.
[Edited by Torque Monster - 7/19/2002 11:34:35 PM]
19 July 2002, 11:36 PM
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Surely its just turbo lag ??? pre 98 Subaru turbos had a large turbo which doesnt spool up very quickly causing lag.
Cars after 98 had smaller turbos which spool quicker so they pull lower down the rev range.
Andy
Cars after 98 had smaller turbos which spool quicker so they pull lower down the rev range.
Andy
19 July 2002, 11:39 PM
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Hi torque monster, from your reply can I assume that this is normal behavior for the impreza. Have only had the car a couple of weeks so have I gotta alter the way I drive to suit the car Hi attu, have fittedn forge dump valve does'nt that help spool up at low revs
[Edited by toplad! - 7/19/2002 11:47:55 PM]
[Edited by toplad! - 7/19/2002 11:47:55 PM]
19 July 2002, 11:47 PM
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The big turbo really is a blessing - some would give body parts for the sort of top end your car could produce, yes it is normal as Andy says. If you are increasing the power the standard intercooler is lacking.
Strictly lag and boost threshold are two different things. Boost threshold is the point where the turbo actually does something useful - eg. 3000 RPM. Lag is the time it takes for the turbo to reach required boost when you open the throttle at an efficiency point suited to the turbo - say on yours at 4500 RPM. So bigger turbos suffer with a higher boost threshold and more lag, but they produce a cooler, denser charge with less exhaust back pressure resulting in more top end power
[Edited by john banks - 7/19/2002 11:48:44 PM]
Strictly lag and boost threshold are two different things. Boost threshold is the point where the turbo actually does something useful - eg. 3000 RPM. Lag is the time it takes for the turbo to reach required boost when you open the throttle at an efficiency point suited to the turbo - say on yours at 4500 RPM. So bigger turbos suffer with a higher boost threshold and more lag, but they produce a cooler, denser charge with less exhaust back pressure resulting in more top end power
[Edited by john banks - 7/19/2002 11:48:44 PM]
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