How much power loss with cats?
TECH Resident
Joined: Dec 2004
Posts: 845
Likes: 0
From: K-W, Ontario
Do you know the flow ratings of the catalytic you have listed?
What is your peak shift RPM going to be?
Just off the top, a good flowing 346 CI motor will need a minimum of 650.7 CFM
(unrestricted exhaust flow) at 6200 RPM.
That's a basic theoretical calculation using 100% V.E. at sea level.
What is your peak shift RPM going to be?
Just off the top, a good flowing 346 CI motor will need a minimum of 650.7 CFM
(unrestricted exhaust flow) at 6200 RPM.
That's a basic theoretical calculation using 100% V.E. at sea level.
TECH Resident
Joined: Dec 2004
Posts: 845
Likes: 0
From: K-W, Ontario
Flow = Power
If there is a 'claim' to 54% more flow, it should open up enough air-way to
get the full potential of exhaust gas out.
Aside from pulse tuning, those cats should get you about 15-20 HP at the
crank based on the following:
I believe the stock CFM for an LS1 cat. is about 315 CFM
315 CFM * 2 = 630 CFM
If the stock cats make 325 HP @ 6000 RPM
then we can infer the following:
630 CFM / 325 HP = ~ 1.94 CFM / HP
A totally unrestricted engine will make 100% of the power at close to 650 CFM (minimum)
That would mean there is a loss of about 5% in the system
If you install the aftermarket cats:
325 HP * 5 % = about 341 HP
I know it's a crude calculation, but that will hold you over until you hit the dyno.
Please note, that's not the maximum power, but the estimated loss from
the theoretical value. 54% more exhaust flow would equal more power,
but we all know we're not going to see 54% increase from a catalytic swap!
IOW, a catalytic with 20% more flow will yield the same results all else being
equal.
If there is a 'claim' to 54% more flow, it should open up enough air-way to
get the full potential of exhaust gas out.
Aside from pulse tuning, those cats should get you about 15-20 HP at the
crank based on the following:
I believe the stock CFM for an LS1 cat. is about 315 CFM
315 CFM * 2 = 630 CFM
If the stock cats make 325 HP @ 6000 RPM
then we can infer the following:
630 CFM / 325 HP = ~ 1.94 CFM / HP
A totally unrestricted engine will make 100% of the power at close to 650 CFM (minimum)
That would mean there is a loss of about 5% in the system
If you install the aftermarket cats:
325 HP * 5 % = about 341 HP
I know it's a crude calculation, but that will hold you over until you hit the dyno.
Please note, that's not the maximum power, but the estimated loss from
the theoretical value. 54% more exhaust flow would equal more power,
but we all know we're not going to see 54% increase from a catalytic swap!
IOW, a catalytic with 20% more flow will yield the same results all else being
equal.
