liquidflem
Member
- :
- MS3
Stock vs. Forge BPV Boost
- Thread starter liquidflem
- Start date
drledford93
Member
- :
- Mazdaspeed 3
Interesting. So if the pressures don't go so into vacuum, then the turbo will recover more quickly, correct?
Also interestingly, it seems that the stock bpv allows higher boost in 3rd, but generally lower in 1st and 2nd. Boost does seem to come on faster, validating what most have said. Can't wait to get mine in the mail!
Daniel
Also interestingly, it seems that the stock bpv allows higher boost in 3rd, but generally lower in 1st and 2nd. Boost does seem to come on faster, validating what most have said. Can't wait to get mine in the mail!
Daniel
Darth Vader
Member
Yeah, heavy manifold vac stalls the turbo dead in its tracks. You have boosted air bashing up against a closed throttle plate and the bounceback stalls the compressor. That's why flatshifting makes this car sing like a bird.
Darth Vader
Member
Right, I say Forge reacts faster to lifted throttle-opened throttle event like a regular WOT granny shift. It's *bang* open and *bang* closed. Plus, I found it doesn't want to flutter about at light throttle, improving throttle response and low-speed torque.
Saskatchewan17
Member
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- 2008 TR Mazdaspeed 3
Wow. I need to get a Forge back! I miss my old one...
AllLostThings
Member
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- 2007 Mazdaspeed 3
I can't wait until I get the repair kit for mine in the mail. I miss the sound and performance.
Am I seeing that the stock BPV allows higher sustained boost in third gear than the Forge?
Can we really use all the power we have in first and second gear anyway? I break 'em loose all the way through second now if not very careful.
What were the other mods on the car? What was the AP tune? Stock type map or modified?
What am I missing, here? Doesn't this dispell the notion that the stock BPV leaks or won't hold boost at full load?
Looks like once the car gets into third the stock BPV is building and holding better boost, IMHO.
I agree that without the time or rpm intervals on the chart, you really can't tell much about when and where these changes are taking place, but it is very interesting. But if you are buying the valve for true performance and tracking the car, are you really going to be granny shifting and letting the throttle plate close between shifts?
It would be great to see how the two valves compare in 4-6 gears where there is much greater load on the engine at WOT.
Can we really use all the power we have in first and second gear anyway? I break 'em loose all the way through second now if not very careful.
What were the other mods on the car? What was the AP tune? Stock type map or modified?
What am I missing, here? Doesn't this dispell the notion that the stock BPV leaks or won't hold boost at full load?
Looks like once the car gets into third the stock BPV is building and holding better boost, IMHO.
I agree that without the time or rpm intervals on the chart, you really can't tell much about when and where these changes are taking place, but it is very interesting. But if you are buying the valve for true performance and tracking the car, are you really going to be granny shifting and letting the throttle plate close between shifts?
It would be great to see how the two valves compare in 4-6 gears where there is much greater load on the engine at WOT.
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drledford93
Member
- :
- Mazdaspeed 3
Couldn't you almost assume that the intervals are based on RPMs rather than time? That would seem most logical, as there are equal "reports" per gear.
I also noticed that if you assume 1psi boost = 5hp, then the first interval shows that you have an extra 50-65 hp available earlier that you don't with a stock bpv...yikes!
Daniel
I also noticed that if you assume 1psi boost = 5hp, then the first interval shows that you have an extra 50-65 hp available earlier that you don't with a stock bpv...yikes!
Daniel
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Darth Vader
Member
Honestly, I put the valve on cuz I could, it was inexpensive. I had no expectations about performance improvements since my stock valve didn't leak. It did have annoying tendencies when paired with an aftermarket intake, namely, the fluttering and generally soft throttle response mentioned earlier. Somewhat unexpectedly, the Forge fixed that little problem right away.
Not really science but, it gave a driveability and enjoyment mod, more than maximum performance objective.
Not really science but, it gave a driveability and enjoyment mod, more than maximum performance objective.
liquidflem
Member
- :
- MS3
It probably records time every "x" interval of time and since you go so quickly through 1st gear, it only had time to record 5 entries (ok... total guess). I agree, more measurements are always welcome
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liquidflem
Member
- :
- MS3
This car is AP tuned, yes. They do not say what spring they are using either. The car also has a full on cold air intake, but no other exhaust or intake mods, currently.
I agree that this car shifts much more smoother when not letting off the throttle fully during shifts, especially in the first few gears.
What works well for me:
First -> second = lift partially and be very quick back on the throttle during clutch engagement (flat shifting just leads to ridiculous wheel spin)
Second -> third = flat shift and hope the syncros match in time and you don't rev too high (wonderfully smooth with tire chirp if you do it right)
rest of shifts = less aggressive partial throttle lift shifts.
I'll scan the whole page when i get a chance. Also there are 2 other issues that are Project car mazdaspeed3 part 1 and 2. I have these as well and will create a PDF for you guys today or tomorrow.
H3br3w_Ham3r
Member
- :
- 2008 Mazdaspeed3
Or install AP flat foot shifting and two step and flat foot shift every gear! Who needs turbo lag?
I'm sure you are right.
If one of my colleagues presented data like that in an engineering meeting, he would be fired. There is no way to really determine anything from that data (except that the OEM BPV doesn't leak).
Questions:
1) Did the Forge valve open between shifts? According to the data, there wasn't enough vacuum (it should take a fair amount of vacuum to open a BPV).
2) Why should the Forge valve react faster? Does the OEM BPV have a cast iron piston???
I would want to see a high resolution graph with boost/vac and accel pedal position
Darth Vader
Member
Harsh, man...the guy ain't presenting a peer-reviewed paper, just his own data point. Ditto, I just shot out there what my experiences have been with the Forge since installing it. Whatever did it, it's better than stock though, I think stock would probably have been fine...if I stayed with the stock airbox.
Something that caught my eye upon inspection of the stock valve that maybe you can shed some light on. There seems to be a small hole in the base of the valve that looks like it might join the manifold side of the valve to the spring side, essentially bypassing the valve part altogether. Is that what it does and what's the purpose of that?
Now back to my holiday (couch) (drinks)
Something that caught my eye upon inspection of the stock valve that maybe you can shed some light on. There seems to be a small hole in the base of the valve that looks like it might join the manifold side of the valve to the spring side, essentially bypassing the valve part altogether. Is that what it does and what's the purpose of that?
Now back to my holiday (couch) (drinks)
drledford93
Member
- :
- Mazdaspeed 3
You do realize this is an internet message board that is for fanatics of a certain car, right? This is no peer-reviewed journal site...(gossip)
In spite of what you said above, you make this claim by seeing this in the data. How do you come to this conclusion?
Silver Ecstasy
Member
- :
- 11 MS3 Sport
I may be a complete opposite in experience with this valve, but my car has not liked this valve.
At 3,000 rpms, I can lean into the throttle and build boost fast and quick (stock). With the Forge valve, the valve shuts so damn fast, the turbo seems to work overtime and it can't really generate any real boost. I'd have to wait till 4,000 rpms before I can do the same kind of acceleration that I could with the stock valve.
I've witnessed other MS3's that really enjoy this valve, but I had negative results and my car didn't hold any higher boost values than stock. Infact, it feels stronger stock.
At 3,000 rpms, I can lean into the throttle and build boost fast and quick (stock). With the Forge valve, the valve shuts so damn fast, the turbo seems to work overtime and it can't really generate any real boost. I'd have to wait till 4,000 rpms before I can do the same kind of acceleration that I could with the stock valve.
I've witnessed other MS3's that really enjoy this valve, but I had negative results and my car didn't hold any higher boost values than stock. Infact, it feels stronger stock.
