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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Fri, Oct-13-2017, 03:51:00 AM   #11
stash1
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Default Re: Good power but low boost. Halp.

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Originally Posted by Tchleung View Post
Power doesn't seem too bad for a mustang dyno. They read low. What's your elevation? High elevation will result in lower boost levels on a centrifugal blower system
Not 100% true Tom...it's one of the misconceptions around Mustang dyno's, that they always read low. As a 'load' type of dyno, they're generally more preferred by tuners because a load can be induced to better simulate actual road conditions. However, that load can be 'dialed out', which will then give readings similar to a Dynojet...or sometimes even higher. It's important to know in this instance how the operator had the dyno set up, but judging from the results (440 HP @ only 8.5 PSI)...I would say that the dyno was probably run in an 'unloaded' state.
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Old Fri, Oct-13-2017, 04:48:40 AM   #12
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Default Re: Good power but low boost. Halp.

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Originally Posted by Tchleung View Post
Power doesn't seem too bad for a mustang dyno. They read low. What's your elevation? High elevation will result in lower boost levels on a centrifugal blower system
Approx 480ft

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Old Fri, Oct-13-2017, 06:21:20 AM   #13
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Default Re: Good power but low boost. Halp.

I don't know a lot about these kits so this could be completely irrelevant but I'll just throw it out here anyway. Could it be possible that the issue is the bypass valve itself? Could the spring in the blow off valve simply be too soft to hold more than 8.5psi? I have no idea what BOV this kit uses or how much boost its rated to hold. Also maybe the BOV is physically damaged like a bad o-ring or something.
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Old Fri, Oct-13-2017, 01:05:07 PM   #14
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Default Re: Good power but low boost. Halp.

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Originally Posted by stash1 View Post
Not 100% true Tom...it's one of the misconceptions around Mustang dyno's, that they always read low. As a 'load' type of dyno, they're generally more preferred by tuners because a load can be induced to better simulate actual road conditions. However, that load can be 'dialed out', which will then give readings similar to a Dynojet...or sometimes even higher. It's important to know in this instance how the operator had the dyno set up, but judging from the results (440 HP @ only 8.5 PSI)...I would say that the dyno was probably run in an 'unloaded' state.
The dyno was loaded @ 3750lbs
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Old Fri, Oct-13-2017, 02:33:51 PM   #15
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Default Re: Good power but low boost. Halp.

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Originally Posted by Turb02 View Post
Yeah, the dyno shop was a bit understaffed and didnt hook the AFR probe to anyones car.

Get some AFR readings. If you have a leak you'll being running rich. I forgot to hook up the bigger vacuum hose on the bottom front of the intake manifold one day and was reading ~1.4 points richer than normal.

Im not sure how I can get to redling in either 3rd or 4th without breaking any laws, to log it on the streets. If I recall, I was at 129mph at the top of 4th on the dyno.

You dont have 2nd gear?? All you need to do is run it to redline under load and keep an eye on your gauge.

After looking at several pics online of people with similar kits, it appears I have a vacuum line attached to the top of my bypass valve to my intake manifold. May research/look at removing that.

The valves need a vacuum source. If you unhook it then the only thing keeping it closed is the spring pressure. They are normally anywhere from 2 to 6lbs... so as soon as boost pressure exceeds spring pressure the bypass valve will open and vent boost w/o the vacuum hose providing pressure to the back side of the valve.


I guess the low boost could be a timing factor?
No, not 3psi worth.

It doesnt sound like you have any issue besides missing boost pressure. 440 whp is about standard for 8-9psi. How did you do the boost leak test? You need more data at this point. Hard to diagnose over the internet w/o seeing AFR or boost graphs. But the shape of your power graphs would have my first guess being belt slip... The way it looks to pull straight up to 6500ish and then get wonky... If you just had a straight leak it'd still build linear but just peak lower.
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I like it on mine, tips didn't line up perfect, but good enough. Its off a newer car that makes more power so I know it makes more power on my car.

You can make a custom flange to connect it to your stock header with JB weld.

Sound is an 8/10, I was expecting it to sound like a V8 since its a V8 exhaust. It doesn't, anybody know why this is? Does it have to do with how I installed it?
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Old Fri, Oct-13-2017, 02:44:27 PM   #16
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Default Re: Good power but low boost. Halp.

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Originally Posted by Turb02 View Post
The dyno was loaded @ 3750lbs
Quote:
Originally Posted by CharlaybitM3 View Post
It doesnt sound like you have any issue besides missing boost pressure. 440 whp is about standard for 8-9psi.
Hey brother, not gonna debate you here, but I've seen bunches of S/C cars on dyno's, and 440 WHP @ 8.5 PSI DOES sound about right..pretty sure that Mustang dyno was run in an 'unloaded' state. Some shops w/load type dyno's run them in an unloaded state (especially on 'dyno days') because they don't want customers to get their feelings hurt when they see numbers WAYY lower than expected...very common practice.

EDIT: Trust me, if that Mustang dyno was run in a loaded state, your final number would have been closer to 400...or even a little under. As has been stated on here many times, don't get hung up on max numbers from either type of dyno, but instead focus on the area under the curve and the delta between 'before' and 'after'.
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Old Fri, Oct-13-2017, 03:08:19 PM   #17
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Default Re: Good power but low boost. Halp.

Quote:
Originally Posted by CharlaybitM3 View Post
It doesnt sound like you have any issue besides missing boost pressure. 440 whp is about standard for 8-9psi. How did you do the boost leak test? You need more data at this point. Hard to diagnose over the internet w/o seeing AFR or boost graphs. But the shape of your power graphs would have my first guess being belt slip... The way it looks to pull straight up to 6500ish and then get wonky... If you just had a straight leak it'd still build linear but just peak lower.
Boost leak test was performed on the SC inlet.

The belt is brand new (one week prior to the dyno day) and so is the tensioner pulley. The tensioner on the other hand, has not been replaced...so maybe it is weak??

Im working on building a Raspberry Pi to log AFR, Boost, and RPM. That way I can either overlay that data with Pro Logger or Testo.

I do notice that if I ease into throttle and linearly depress the pedal, my boost climbs decently, but if I floor it, it climbs, then drops slightly and then begins to climb again.

Quote:
Originally Posted by stash1 View Post
Hey brother, not gonna debate you here, but I've seen bunches of S/C cars on dyno's, and 440 WHP @ 8.5 PSI DOES sound about right..pretty sure that Mustang dyno was run in an 'unloaded' state. Some shops w/load type dyno's run them in an unloaded state (especially on 'dyno days') because they don't want customers to get their feelings hurt when they see numbers WAYY lower than expected...very common practice.

EDIT: Trust me, if that Mustang dyno was run in a loaded state, your final number would have been closer to 400...or even a little under. As has been stated on here many times, don't get hung up on max numbers from either type of dyno, but instead focus on the area under the curve and the delta between 'before' and 'after'.

Im not chasing the highest number, so your info is helpful. This was a baseline run for my reference.

I do know that the owner of the shop created profiles and selected each cars profile from a list in his dyno computer, and when we swapped cars, he loaded these profiles. I ASSumed this was changing the load for each car. I explicitly asked about the weight of my car in the profile and he said that he added his weight (since he was in the car on the dyno) to the weight of the profile in the computer.



Thanks for everyones responses!
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Old Fri, Oct-13-2017, 04:42:30 PM   #18
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Default Re: Good power but low boost. Halp.

A few things:

Is your W/M system working properly? 8.5psi sounds like a failsafe setting for an intercooled kit. Maybe a passenger could see if the boost plateaus around 6000 up.

I won't debate if the HP numbers are normal or NOT but your torque seems very high in proportion. That makes me think about an exhaust restriction.
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Old Fri, Oct-13-2017, 05:24:02 PM   #19
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Default Re: Good power but low boost. Halp.

Quote:
Originally Posted by jared212 View Post
A few things:

Is your W/M system working properly? 8.5psi sounds like a failsafe setting for an intercooled kit. Maybe a passenger could see if the boost plateaus around 6000 up.

I won't debate if the HP numbers are normal or NOT but your torque seems very high in proportion. That makes me think about an exhaust restriction.
It appears to be working (I've had to fill the tank...). Based on what I read, the w/m kit is activated at 6psi.
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Old Fri, Oct-13-2017, 05:50:23 PM   #20
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Default Re: Good power but low boost. Halp.

I was more referring to the solenoid controlling the vacuum hose to the BOV. It would be audible if it were blowing off though.

What fuel pump are you running?
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Discussing Good power but low boost. Halp. in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)