Ls vs old schools engines vacumn
08-23-2013, 05:52 PM
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Ls vs old schools engines vacumn Ok so I've got a 5.3 I'm going to swap
Into a project. I've called on a good cam and they say a 224/224 112 lsa will push through the brakes with a stock converter and a 114 lsa would be better why was this not an issue with a sbc with a comp 268he the duration 224/230 at .050 on a 109 lsa do these ls motors make less vacumn cause the booster not to keep up
Into a project. I've called on a good cam and they say a 224/224 112 lsa will push through the brakes with a stock converter and a 114 lsa would be better why was this not an issue with a sbc with a comp 268he the duration 224/230 at .050 on a 109 lsa do these ls motors make less vacumn cause the booster not to keep up
08-27-2013, 11:33 AM
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The narrower separation will make it "choppier" but
I'm idling clean at 700RPM with a 116LSA (one of the
reasons I went wide). More to the point, why do you
want to impair your motor performance with a converter
that takes you out of the powerband on every shift?
The 112LSA ought to have lower torque peak RPM so
in some sense it's a better fit (but the stock converter
still sucks in every way).
Vacuum may be depressed due to tuning issues post-cam.
That's unavoidable if you don't tune, and it's some work
if you do tune. Narrower LSA will idle at lower vacuum.
Carbs respond differently to the cam than a too-busy
PCM with a head full of wrong (stale) data. You can't
put it all on the cam, these issues / behaviors.
I'm idling clean at 700RPM with a 116LSA (one of the
reasons I went wide). More to the point, why do you
want to impair your motor performance with a converter
that takes you out of the powerband on every shift?
The 112LSA ought to have lower torque peak RPM so
in some sense it's a better fit (but the stock converter
still sucks in every way).
Vacuum may be depressed due to tuning issues post-cam.
That's unavoidable if you don't tune, and it's some work
if you do tune. Narrower LSA will idle at lower vacuum.
Carbs respond differently to the cam than a too-busy
PCM with a head full of wrong (stale) data. You can't
put it all on the cam, these issues / behaviors.
08-27-2013, 11:59 AM
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Modern complex PCMs do their best to work towards a "perfect" idle under all conditions, monitoring and adjusting several things at every moment to keep engine behavior consistant and within spec. When you start making changes to valve events, the PCM will not be equipped to handle the consequences with a factory tune. Custom tuning can certainly help with this, but the process isn't nearly as forgiving as an old gasoline toilet bowl (carb).
08-27-2013, 01:39 PM
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The narrower separation will make it "choppier" but
I'm idling clean at 700RPM with a 116LSA (one of the
reasons I went wide). More to the point, why do you
want to impair your motor performance with a converter
that takes you out of the powerband on every shift?
The 112LSA ought to have lower torque peak RPM so
in some sense it's a better fit (but the stock converter
still sucks in every way).
Vacuum may be depressed due to tuning issues post-cam.
That's unavoidable if you don't tune, and it's some work
if you do tune. Narrower LSA will idle at lower vacuum.
Carbs respond differently to the cam than a too-busy
PCM with a head full of wrong (stale) data. You can't
put it all on the cam, these issues / behaviors.
I'm idling clean at 700RPM with a 116LSA (one of the
reasons I went wide). More to the point, why do you
want to impair your motor performance with a converter
that takes you out of the powerband on every shift?
The 112LSA ought to have lower torque peak RPM so
in some sense it's a better fit (but the stock converter
still sucks in every way).
Vacuum may be depressed due to tuning issues post-cam.
That's unavoidable if you don't tune, and it's some work
if you do tune. Narrower LSA will idle at lower vacuum.
Carbs respond differently to the cam than a too-busy
PCM with a head full of wrong (stale) data. You can't
put it all on the cam, these issues / behaviors.