Ported LIM plus front PEM test data - Page 5 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


Performance, Brainstorming & Tuning Talk about modifications, or anything else associated with performance enhancements. Have a new idea for performance/reliability? Post it here. No idea is stupid! (please use Detailing and Appearance for cosmetic ideas)

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Old 05-07-2007, 10:51 PM   #41
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Quote:
Originally Posted by hawkjet
Agrazela, could you elaborate on what you mean by "tuned"?
That just means those data were collected after a full tune at that particular level of modification (stock, PLIM, PLIM+PEM).
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Old 05-08-2007, 12:46 PM   #42
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Quote:
Originally Posted by TJ'sblackbonne
Here is a link to a test done by someone on clubgp, http://www.clubgp.com/newforum/tm.as...mode=1&smode=1
Good find. That'* the first attempt at hard data I've seen on the PowerLog (and it'* been on the market for how long?)

I might've gone the PLog route, but:
1) $120 was too much for something that (til that thread) hadn't a shred of backing data
2) $30 for a home-ported PEM was more budget-friendly
3) I can port the EM I took off the '98 for the '04 (making that one effectively free)
4) I've gotta keep my engines looking absolutely bone stock because of the CA smog inspectors
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Old 05-08-2007, 12:50 PM   #43
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Yea, i would say for you a PEM is better suited.
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Old 05-08-2007, 12:52 PM   #44
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Quote:
Originally Posted by willwren
Ag, High flow cat and PEM'* WITHOUT adding material under the chin on the front. He is an L36.
Missed this comment my first few times reading through this thread
(Boldface added by me)

I wonder how much the aftermarket cat had to do with it...time to scour the CA regs to see if there'* any way a high-flow cat can be legally put on my car
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Old 05-08-2007, 02:02 PM   #45
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Quote:
Originally Posted by BillBoost37
Then the question is.. how much reduced backpressure are we willing to give up, because backpressure at the DP is being seen as torque to a degree.
I'll give up ALL the backpressure in the world. Back pressure doesn't give any more torque then an open exhaust system. But opening things up too big creates a loss in velocity.

Just want to clear up the confusion some people have here where they think some backpressure = more torque, this is completely untrue.
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Old 05-08-2007, 02:26 PM   #46
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Jason, this is a fairly common term in the automotive world. A smaller exhaust WILL have a higher backpressure. Think about it. You have a 2.5" pipe flowing at 100cfm. Now open that up to 3" and feed it with the same 100cfm. Which has more velocity AND higher pressure?



Physics 101.
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Old 05-08-2007, 03:28 PM   #47
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We're saying the same thing, different terminology i guess.

I understand that too large a pipe will hurt CFM, and inturn scavenging effects of an exhaust system, but it'* my understanding through many sources, that backpressure is a restriction exclusively. using a 2.5" pipe over a 3" pipe doesn't give more backpressure, unless it'* too restrictive for the given flow.
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Old 05-08-2007, 03:33 PM   #48
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You clearly stated above that you'd give up all the backpressure in the world. Go 4". That'll take care of it.

You are making corrections to terminology used in this topic, and are wrong in doing so. Backpressure, in the sense it was used in this topic, is the same thing as increased exhaust gas velocity. They are INTERRELATED. The author'* INTENT was correct.

Back on topic. I just needed to clear the air of some misconceptions there.
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Old 05-08-2007, 05:18 PM   #49
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Quote:
Originally Posted by agrazela
Quote:
Originally Posted by hawkjet
Agrazela, could you elaborate on what you mean by "tuned"?
That just means those data were collected after a full tune at that particular level of modification (stock, PLIM, PLIM+PEM).
I guess I was unclear...
You tune a guitar to get the strings to play the right notes. You tune a radio to hear the radio station. You tune an exhaust system to have the pipes the right length for the RPM. You tune an intake for the same thing. Or you can give your car a tune-up. You can even play a tune.

Exactly what is a "full tune"?

I'll stay tuned...
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Old 05-08-2007, 07:04 PM   #50
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Quote:
Originally Posted by hawkjet
Quote:
Originally Posted by agrazela
Quote:
Originally Posted by hawkjet
Agrazela, could you elaborate on what you mean by "tuned"?
That just means those data were collected after a full tune at that particular level of modification (stock, PLIM, PLIM+PEM).
I guess I was unclear...
You tune a guitar to get the strings to play the right notes. You tune a radio to hear the radio station. You tune an exhaust system to have the pipes the right length for the RPM. You tune an intake for the same thing. Or you can give your car a tune-up. You can even play a tune.

Exactly what is a "full tune"?

I'll stay tuned...
Will PM
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