How do I eliminate/reduce the lag in second gear?
12-23-2001, 02:23 PM
#1
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How do I eliminate/reduce the lag in second gear?
Ok, Ok...please avoid the KO4 comments...
I have a complaint regarding the lag in second gear. Only second gear.
I can't seem to get a clean 1-2nd shift. It seems that the only way to upshift clean is shift at much higher rev's. But for around town I prefer to shift around 3000-3500 rpm.
First of all, first gear is so short that it's almost useless. Then I hit second gear and there is this momentary lag until that wonderful wwwhhoosshhh comes on. Third is less noticable.
Will BPV's reduce this slight lag?
I have a complaint regarding the lag in second gear. Only second gear.
I can't seem to get a clean 1-2nd shift. It seems that the only way to upshift clean is shift at much higher rev's. But for around town I prefer to shift around 3000-3500 rpm.
First of all, first gear is so short that it's almost useless. Then I hit second gear and there is this momentary lag until that wonderful wwwhhoosshhh comes on. Third is less noticable.
Will BPV's reduce this slight lag?
12-23-2001, 04:15 PM
#4
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nope, if they aren't broke, there is no difference
the turbo's are barely spooled in 1st gear at redline
so 2nd gear is where all the fun starts
on a 2-3 shift, they are already spooled up
so 2nd gear is where all the fun starts
on a 2-3 shift, they are already spooled up
12-23-2001, 04:25 PM
#5
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That said...
...can I assume the raising the shift point on the 1st-2nd upshift to a higher point will allow the turbos to spool a slight bit more and possibly reduce the lag once second gear is launched?
And, how, exactly, do the Forge/Baily BPV improve performance?
And, how, exactly, do the Forge/Baily BPV improve performance?
12-23-2001, 04:36 PM
#7
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yes slightly, depending on stock software or tuner software.. and
aftermarket BPV's only increase reliabilty of the parts
basically any BPV, works as a excess pressure relief valve (sorta like the safety valve, in the water heater in your house, does)
when the throttle plate closes and the exhaust wastegate has opened...BUT, the turbo is still spinning down and making some boost
the BPV (or a BOV, for that matter), is there to dump the excess boost pressure, before it backs up in the piping and "stalls", the turbo completely
the stock Bosch valves seem to display a limited lifespan, and fail to open, resulting in some turbo stall or at least slow down..which adds turbo lag...
aftermarket valves are popular, because they seem to be built of sturdier parts.
than the rubber disc and metal spring, that Bosch uses
basically any BPV, works as a excess pressure relief valve (sorta like the safety valve, in the water heater in your house, does)
when the throttle plate closes and the exhaust wastegate has opened...BUT, the turbo is still spinning down and making some boost
the BPV (or a BOV, for that matter), is there to dump the excess boost pressure, before it backs up in the piping and "stalls", the turbo completely
the stock Bosch valves seem to display a limited lifespan, and fail to open, resulting in some turbo stall or at least slow down..which adds turbo lag...
aftermarket valves are popular, because they seem to be built of sturdier parts.
than the rubber disc and metal spring, that Bosch uses
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12-23-2001, 05:13 PM
#8
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Frank, good explanation, thanks...should I be concerned about the integrity of my stock valves...
if there is obvious lag when launching second gear?
Or, is that simply one of the few "cons" of S4 ownerhship?
I am not opposed to changing the valves...
what's the scoop on the "upgraded" Bosch valves? Worth it or not?
Or, is that simply one of the few "cons" of S4 ownerhship?
I am not opposed to changing the valves...
what's the scoop on the "upgraded" Bosch valves? Worth it or not?
12-23-2001, 05:21 PM
#9
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worth depends on personal choice..I think Bosch 114's and Forges are both good options
the #1 failure in chipped cars is the TBB (even the 356T part)
distant 2nd is BPV's, but mine finally gave out on the pass. side at 30K miles
very distant 3rd is the F-hose, I still haven't personally seen one fail (only here on the net)
but the F-hose only really applies to 2000 and a few early 2001 cars
2001+ have only a L-hose
distant 2nd is BPV's, but mine finally gave out on the pass. side at 30K miles
very distant 3rd is the F-hose, I still haven't personally seen one fail (only here on the net)
but the F-hose only really applies to 2000 and a few early 2001 cars
2001+ have only a L-hose
12-23-2001, 06:25 PM
#10
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Depends on launch
The engine revs up too fast in first too get the turbos spinning, unless you load it before engaging the clutch. I have not perfected this yet, but by blipping the throttle and engaging the clutch just as rpm is increasing at about 3000 rpm with just a little clutch slip you can do a quick shift to second with some boost built up.