You just discovered something important: a single dyno run in itself is useless. You NEED to have a run to compare to, and not any run; a run that was made with the same car, on the same dyno (same brand/model, at least), on the same kind of weather, at the same altitude.

A single run can give you an idea of what's going on, but that's it; an idea.

The flywheel hp is extrapolated from the whp. That alone should ring a bell. You can't have 100% confidence in an extrapolated number; their will always be some error margin. On a wheel dyno, it's always best to compare whp rather than extrapolated flywheel hp.

 

Agarwal has it all.

You also have to factor in the age of the car, temperature (was it SAE corrected?), etc. You could have slight compression losses, even on a relatively new car.

 

Unless you did a baseline run, there's no way to tell what your mods did.
I would go back to that dyno operator and ask for a WHP dyno printout or your fee back. They cannot tell flywheel HP. It's impossible. Ask him for the HP/Torque figures to the wheels, that is the ONLY force you can accurately measure. Anytime anyone quotes "flywheel" HP figures, don't walk away, RUN away. They are FULL OF SHEIT. They use estimates of "flywheel" HP figures because it makes the cars look/sound more powerful (just like the OEM's do). However, the OEM's actuall MEASURE the engine on an engine dyno. Your local schmuck is simply guessing how much power you made at the flywheel by adding a percentage to your wheel HP figure. It's a wild Azz guess, nothing more.

Regarding the backpressure thing, that's been covered time and time again. To sum it up. Backpressure in exhaust is NEVER DESIREABLE. Let me say that again. Backpressure in exhuast is NEVER DESIREABLE. You'll never see mufflers or cat converters on race cars. Ever wonder why? Simple. BACKPRESSURE =BAD. That being said, exhaust systems(location of cat, location of muffler, length of pipe, etc) can be tuned to reflect pressure waves (waves, not static pressure) that will aid in cylinder filling at a certian RPM or RPM range. If you've ever seen a stock car dyno, nearly all have smooth flowing lines, with no "dip" or "holes". If you look at dyno with a pieced together aftermarket exhaust, you'll often find "dips" or "holes" in the torque delivery. The reason is that the stock system was designed to refect the pressure waves back to "help" the engine breath to fill in those dips/holes, and the cobbled together bits of aftermarket exhaust don't do that.

I would take the dyno operator at his bet. Add up all the areas you loose power because of the cat, and add up all the area's you gained power due to the cat. at a 1000:1 ratio of his bet, you'd always come on out top. smile.gif

 

^^^just about to say.

your car might be making 142whp, which is pretty good.

 

How did you measure flywheel hp? You took your tranny off to do so???....

If it's flywheel hp then you either have an old engine, it was very hot out, your intake robs your power.

If 142whp then it's pretty damn good for just a catback and a WAI.

 

^ Agreed. That's not bad at all. I think some of the dyno runs before placed our base HP at like 118 or 120 tops.

That's a decent improvement, man. If you don't want those parts anymore, you're more than welcome to send them my way. LOL

 

why dont you scan the piece of paper they gave you so we can see what the hell the shop was thinking...

.... please say they gave you a print out...

 

after you do what he said^ go in your engine bay and take off the air filter from the MAF. Put a CAI in it's place and place the intake filter in the fender well...(AEM intake)

 

Look at the pictures again...he doesn't have a MAFS. His car is MAP based. laugh.gif

Unfortunately that also means the AEM wouldn't bolt on, he'd need another piece of pipe made.

 

lol yeah i've got GT headers, downpipe, high flow cat, 2.25's full cat-back exhaust and i've spent over $2,000 USD. I've got all of my sensors in. I've gained no more than 3 horsepower from this sh*t.

maybe it's the weight of my rims and tires. maybe it's meineke's fault for putting in an extra bend. maybe it's my evaporation cannister hogging power. maybe it's just my automatic transmission.


was it worth it?

N. O. mad.gif

that's where my supercharger comes in smile.gif