Exhaust System Question

wspohn · 08-27-2009, 05:43 AM

I see several vendors with alternatives for cat back exhausts, and they offer numbers in support in regard to power increases.

One point - clearly the ones that offer both RWP and flywheel power ratings haven't actually measured both, but have probably put the car on a chassis dyno and are extrapolating back to flywheel net power using a conversion factor that may or may not be accurate.

That aside, however, I see claims that a 3" system is advantageous on the LNF engined cars as being a step up in terms of lower back pressure. They even make this claim when their joint to the cat remains a bottleneck with a stock diameter.

Having looked at the stock system, which seems to be quite decent, I have one question that I haven't been able to find the answer to. Has anyone simply sawed off the stock muffler and put a car on a dyno.

The reason I ask is that larger pipes and different pipe layouts aside, I would like to quantify just how much of any improvement offered by these after market systems is simply a function of changing a restrictive muffler for a less restrictive one.

It would be rather interesting in fact if most of the power loss was attributable to the muffler and this could be addressed back there without changing everything back of the cat. Obviously I don't know the answer to this but wondered if anyone else had hacked off a muffler and dynoed the car before and after.

snaponbob · 08-27-2009, 06:59 AM

If you have not installed a tune, or don't intend to, a 3" exhaust will provide a bit more torque. All the claims of X hp and torque are garbage as the ECM "learns down" the advantage. But they ARE lighter and sound better. The MagnaFlow system DOES have a 2.5" neck at the junction with the cat. The Solo Performance systems do NOT. I own both MagnaFlow and SP systems. The stainless that SP uses seems much nicer than the MF. Frankly, the SP systems are all around much better for our cars and Jeff is fantastic to work with. ABSOLUTELY stands 100% squarely behind his products.

Lopping off the stock muffler will require a proper installation of an exhaust pipe as the exhaust is quite hot and will melt stuff under the car (don't ask!!) and you'll still have a 2.5" exhaust system. Only a tune (and it really SHOULD be a Westers) will release the rest of the power your engine can produce.

wspohn · 08-27-2009, 07:24 AM

I had assumed that one had a GMPP or other tune, as it would be impossible to measure any difference otherwise, but you are right, I should have said it.

I note that none of the manufacturers of supposed power adders make a point of saying "If you don't get a new tune you'll get zip out of our product and are throwing your money away"....

And yes, you would need something to duct the exhaust gas away after hacking off the muffler (that SHOULD be equally obvious, but again, I agree that saying it might avoid a fire or two). It doesn't need more than a couple of lengths of flex pipe and a couple of clamps while it is on the dyno.

rob the elder · 08-27-2009, 07:38 AM

There is another thread that is addressing basically this same question. Recommend you look over there.

Everything I have found in my research indicates that adding an after market cat back does nothing for power or torque. It makes it sound better. Like the factory intake, the exhaust works well enough so it is not a limiting factor according to what I have read and seen. So adding a catback that increases flow does not add performance.

Going to a high flow cat does apparantly have a positive impact. I have seen dyno numbers in the range of +15 to 18 HP when going from the factory cat to the Solo high flow cat.

wspohn · 08-27-2009, 07:51 AM

Quote:

Originally Posted by rob the elder

There is another thread that is addressing basically this same question. Recommend you look over there.

I hadn't noticed that, Rob. Do you have the url?

GaryH · 08-27-2009, 08:30 AM

Like snaponbob, I have both the Magnaflow and Solo. The MF is on my 07 2.4 and I like the sound and the looks of the quad tips. As far as HP improvement, I can't tell any difference. I have the Solo quad tip on my wife's 2.4 DDM supercharged Sky. I also have the Solo hi-flow cat on my wife's car. The Solo exhaust combined with the hi-flow cat and the whine of the supercharger is a little louder than I would like, but not too bad. The increase in HP and torque with the supercharger was so much that it's hard to notice any gains the cat and exhaust made. I like the looks and design of the Solo better and as stated above, you can't get any better than Jeff.

DRM · 08-27-2009, 09:21 AM

Quote:

Originally Posted by wspohn

I hadn't noticed that, Rob. Do you have the url?

Maybe this one:

Exaust Upgrade GXP..More H.P & Torque???

rob the elder · 08-27-2009, 12:42 PM

Quote:

Originally Posted by DRM

Maybe this one:

Exaust Upgrade GXP..More H.P & Torque???

Yes, thanks

snaponbob · 08-27-2009, 04:35 PM

Quote:

Originally Posted by rob the elder

Yes, thanks

I responded on that thread. Respectfully, we differ. What YOU may seen may not be enough. If somebody wants to pay me for the time and dynos, I will reinstall my stock exhaust on my Wester's tuned Redline and run it against pulls I have already taken. If there is less than 5HP difference, it will be MY dime !!!!!!! Takers? I'll even give you the phone number of the dyno shop if my posted charts are not enough proof. There is NO "relationship" there so he has no dog in the hunt.

wspohn · 08-27-2009, 05:07 PM

Quote:

Originally Posted by snaponbob

I responded on that thread. Respectfully, we differ. What YOU may seen may not be enough. If somebody wants to pay me for the time and dynos, I will reinstall my stock exhaust on my Wester's tuned Redline and run it against pulls I have already taken. If there is less than 5HP difference, it will be MY dime !!!!!!! Takers? I'll even give you the phone number of the dyno shop if my posted charts are not enough proof. There is NO "relationship" there so he has no dog in the hunt.

Well clearly that is exactly the sort of experimental data we need.

Anyone that put it on a car that doesn't have the stage 2 GMPP mod is useless as far as data as it doesn't do dick (no offence to anyone named Richard).

We need someone that has a stock exhaust plus the GMPP upgrade, gets it dynoed with stock exhaust, changes the system, maybe drives it a week (don't know if changes take place immediately) and redynos it.

I'll line up on the curious side - I'd love to see if the manufacturers numbers can be borne out by independent testing.

snaponbob · 08-27-2009, 06:16 PM

Quote:

Originally Posted by wspohn

Well clearly that is exactly the sort of experimental data we need.

Anyone that put it on a car that doesn't have the stage 2 GMPP mod is useless as far as data as it doesn't do dick (no offence to anyone named Richard).

We need someone that has a stock exhaust plus the GMPP upgrade, gets it dynoed with stock exhaust, changes the system, maybe drives it a week (don't know if changes take place immediately) and redynos it.

I'll line up on the curious side - I'd love to see if the manufacturers numbers can be borne out by independent testing.

I do not have the GMPP setup. When Lyndon says "buy it" I will. Until then, his tunes are being applied to stock sensors.

spiky3480 · 08-27-2009, 06:42 PM

Same here...I was told to wait on buying the GMPP because he might be able to get the same power out of the factory sensors. It is too early to tell, and there are some things in the works that a few of us are not able to speak about, which further keep me from buying the GMPP sensors.

wspohn · 08-27-2009, 07:28 PM

Only problem for me is that only one tune is legal - GMPP. I would rather not invalidate my warranty right after I got the car!

In 3 years, we'll see.

But for exhaust effectiveness, and tune that takes out the torque limit from the program will do the trick.

DRM · 08-27-2009, 08:51 PM

Quote:

Originally Posted by wspohn

Well clearly that is exactly the sort of experimental data we need.

We need someone that has a stock exhaust plus the GMPP upgrade, gets it dynoed with stock exhaust, changes the system, maybe drives it a week (don't know if changes take place immediately) and redynos it.

Well I have the GMPP upgrade and stock exhaust. How do I find someone local to me that I can have my car dynoed at?

King-Oka · 08-27-2009, 10:01 PM

As an owner of a 2.4 Supercharged setup, and someone who drove nearly a year on the stock exhaust, I can tell you the Solo setup does add something. If nothing else, the car now breathes correctly. No engine ping/rattle due to exhaust back pressure any more. Also - it seems the clutch is becoming inadequate - sounds like more WHP to me. I'd be interested in seeing comparitive dynos on N/A's as well as Turbo setups, as I believe it helps them all.