smarty

 

A while back Magnaflow had an open house with free food and dyno pulls showing off their new X pipe and exhaust system. After a couple of hours with a couple hundred people milling around the selected winner got the new Magna system installed of which they did a before and after, lost 8 rwhp, got real quit around there.

 

Maybe those two need to get a room?!

 

I wouldn't say that it has no meaning.

I would say that it lacks the specific meaning agreed to by people that make such measurements for a living for tests that are proven to be repeatable and reproducible. Then the tests may also may need to be done enough times to generate a big enough sample to support a hypothesis test. The test would have to be done based on agreed to parameters, etc. Of course, we could monkey with the paramaters and rig the test, too.

I would certainly say that it has less meaning than if all of the appropriate work to support a statistically valid test were done. However, for a test of a $70 spacer, I doubt that anyone other than the manufacturer would bother. The expected value of perfect information wouldn't be enough to justify the test. Sometimes when we have to say something but can't afford a truly valid test we just have to be practical, maybe take an everyday risk, and settle for an inconclusive test result that might be a useful indication when combined with unbiased, seasoned reason. Saying that the test has no meaning is not useful in those cases

I have also observed the trend that you mentioned about the second dyno pull being higher. This happened on the one and only dyno session I have ever put my car through. However, the readings were less than 2HP and 2FTLBS apart. I have seen others 5 higher. Perhaps that is why Vararam's quote of LAPD's test results said 4-6HP.

 

How many would one have to attend? I've probably been to a dozen different "dyno days". I dynoed my '99 Camaro over a dozen different times, 3-4 pulls each time (learning from it that it's a good way to fry your cats), my C5 6-7 times, and my C6 only twice. I know the owners of 3 local shops, and have observed many pulls aside from the ones I already mentioned.

Most of the "variance" that I've seen has been between the first and second pulls. IMHO, this is often caused by the carbon built up in the engine by daily driving. You can usually see it shooting out the tailpipe on the first pull. The third pull often drops off because the engine is hotter, and heats up the incoming air. I've also seen cat overtemps cause the ECM to richen the A/F mix to cool off the cats, dropping a few ponies in the process.

Whatever point I was supposed to see escapes me.

My opinion is that the "variance" that is often talked about is between two different dynos from the same manufacturer, not between two different pulls on the same dyno.

 

The point is and didn't think I had to clarify it. You will get normal output HP deltas from consecutive pulls and to say with a single pull the increase was with the addition of a spacer when it probably was do to warmer oil or less carbon you name it. That's why you need to do repeatability tests to see what caused the variance. That is standard test procedures which don’t seem to be adhered to in this industry when people are trying to sell things.

 

So you think Vararam made their claims based on a single pull? I don't think so. To the contrary, I have found their testing to be fairly exhaustive.

Anyway, I can understand why some folks are natural skeptics, and everyone is entitled to their own opinion. Until I see some repeatable test results showing that the spacer doesn't work, I'll stick with MY own opinion.

 

I think we are addressing "tuning", not manufacturers published claims.

Dyno is just another "tool"

That's why you do multiple "before and after" pulls....

You're not looking at a "hard number" but the relationship to a comparitive number, no more, no less.

If you show a gain, then you prove/confirm it out on the track.
If you show a loss, you reverse what you just did.

Was true forty years ago and still holds true today

 

imo, when using a dyno, one must establish a 'baseline'.

usually, not obtained from one or two pulls. you run her, get her warmed up. she needs to be ridden hard for at least 50 miles before she will even think about being ready. you then, 'baseline' her with back-to-back runs, careful not to make her puke. she needs to be consistent at least 3 out of 5 times.

 

I heard the spacers whistle is that correct?

 

i never heard a whistle, i passed my neighbor and he said he heard a sound like a train or jet coming from behind him, then as i passed he heard like a loud explosion , it scared him, he didnt no i was passing, and i passed him very fast

 

Was that a sonic boom Dennis?

 

Now you guys got me thinking of getting a spacer. I already have a VR and FAST (+ H/C) Am I looking at tuning issues with the addition of the spacer? What kind of fitment issues will I have with the Fast and VR already on?

 

Will a spacer fit on an LS with a FAST and VR without any problems? Also, will I need a retune?

 

I am an avid fan of the VR cai & have used my spacer from the orig. install. It's mated to a FAST 90 on an '05 LS2. I have suffered vacuum leaks at the spacer over & over which thows a CEL along w/ the obvious probs of a vac leak. I have tried many variations of the installs, differing torque on fastners, using orange RTV to create gasket (both sides), to name a few. Sooner or later it always seems to come back & leak. I believe there's gain & I want to keep it on, do you have any solutions/suggestions to keep the setup from leaking. Like I mentioned, keep in mind it's mated to a FAST 90.

If you would please, send a PM w/ your thoughts. Thanks in advance.

 

 

Mine leaked as well, but with the stock manifold... So i just took it off. Couldn't tell a difference in power or throttle response, but that's just me.