Forge BPV sound...

[drledford93]

We should all enjoy the mods we make. But we must be realistic about what they actually do for performance You can set the Forge carefully enough to make it more "lively" when you granny shift. But, please understand that being more lively at light throttle does not make the car either faster or quicker. It comes at the cost, according to the tests results in the study I posted, of losing a pound to almost two pounds of boost at WOT in third gear and above.

All of the "lively" difference goes away when you flat shift.

Here's an example perhaps a bit better than butt dyno of performance with the flat shift with the stock valve and simiple mods listed in sig:

Charts were generated by use of a G-Tech Pro accelerometer and confirmed by a recent video of a timed 40-120 run. Get out your stop watch for if you want something a little better than a butt dyno. And then tell me if the stock BPV is lively enough for you.

Just trying to bring a little objective evidence-based science to the discussion.

http://www.youtube.com/watch?v=pRY2wCDcfWA

The video'd run might have been quicker but for the traction loss (even with DSC ON) in second gear and part way through third (time for new tires).

Now really, how often do you go flat out and shift without lifting? You really must not like your clutch/tranny/diff. I particularly like mine, so I don't.

I beg to differ about the negating of differences due to 1-2lbs of boost diff. Look closely at 1st and 2nd. You're talking IIRC 10-13lbs difference at the commencement of the run. That's HUGE (50-65 hp) vs a small (5-10 hp) diff.

Evidence-based my patootie. Do you think your "evidence" is scientific? Get over your bad self. Jeez. This thread wasn't even about this and you had to hijack it. Thanks.

Daniel

 

[MSMS3]

Sorry I offended. That was not my intent.

I do drive the piss out of my car, now at 28,000 miles. A lot of tracking, a lot of 60 ft. practice, and a lot of runs at WOT up through the gears, especially trying to develop good technique to make that tricky 2-3 shift at WOT without missing third. And yes, I do frequently, very frequently flat shift when I make WOT gear changes.

I discount increased or ealier boost recovery in first or second gear. We simply have way too much power in a fwd vehicle to use any extra boost in those gears unless we are tracking with drag radials or using racing rubber on a road course. Then it would really matter.

That's the reason I posted the charts and the video, attempting to show that the stock BPV does quite well, even with mods that let the engine produce up to 18 psi sustained boost. And 18 pounds of boost is a huge thing. Quite a difference in performance if you can take advantage of it. Measuring things seems more objective that seat of the pants impressions. The Grassroots chart confirms OP's subjective belief that if adjusted accordingly, the Forge can be more responsive to boost recovery, at least in the lower gears with lift throttle shifting.

I found it interesting that when Car and Driver first tested an '07 MS3 a Mazda engineer gave them advice on launching the car and specifically suggested flat shifting, saying "go ahead, it won't hurt it." In fact, the risk in flat shifting is not really to the clutch, but to the engine if there is no rev limiter. You can bend valves and destroy an engine that way. But we are blessed with an excellent soft limiter that prevents damage and does not abruptly kill power when you hit redline, but rather simply holds rpm there without making the engine miss or otherwise behave badly. There's no point in doing it in a 1-2 shift, but from 2-3 on up, you can gain 2 tenths of a second at each shift.

I had understood the beginning of this thread to be a discussion of the unusual sounds of the Forge, which some do not particularly like, weighed against the sense that the Forge gave a more lively feeling when shifting slowly, if set up properly.

I thought I was being faithful to that. If I got us off topic by pointing out that the stock valve stayed away from those unusual sounds and actually held boost better, while being less aggressive in boost recovery when shifting slowly, that was my bad. I do believe expressing differing points of view is one of the main purposes of this forum. If I stepped across the line, I apologize.

 

[ElGaspo]

regarding the peculiar sound of the Forge, the best description I've ever read is:

"The sound of God drinking an ocean through a straw, followed by a hamster sneezing."

I can't recall if it was this forum or another, but it proved to be quite the jocular post, w/ a lot of merriment ensuing. The author even decided to put the quote in his sig line, IIRC.

The best i could've come up w/ is 'clashing ninja swords.' I likes my Forge, would not go back to stock. As for others valves, well...let's just say that i'm at an age where if the mod works for you, you tend to be happy & leave well enough alone. I've read of ppl building a veritable collection of BOVs and going back & forth. More power to 'em. I's staying put.

 

[NCZ13]

Mines going to be changed for the pure fact i enjoy the sound. Im not noticing any boost leak with the stock one.

In fact ill probably be the guy that has two or 3 valves for the sake of changing tastes in sound.