Less boost after SC pulley upgrade?
#1
Less boost after SC pulley upgrade?
I just replaced the coupler and pulley in my M62 this weekend. I changed the pulley from a 2.8 to a 2.5. I also pulled the TB, alt, and valve covers. Once I had it all back together I started it up and everythig ran perfect. So I took it out on a test drive and I noticed the Boost gauge was only reading to about 5-6 psi in the top end of the rmp range. It would jump to around 8 psi when shifting into 2nd. There is more power there. 2nd gear goes like a bat out of hell but the boost only registers between 5-8 psi. Even when launching I can light 'em up better but it just doesn't register the boost at higher rpm'*.
I checked all the connections and they seem fine. I am wondering if the facrory airbox could be chokeing it down? A lack of incomming air at higher rpm'*? I am planning on getting a CAI REAL soon but wondering what you all think?
I checked all the connections and they seem fine. I am wondering if the facrory airbox could be chokeing it down? A lack of incomming air at higher rpm'*? I am planning on getting a CAI REAL soon but wondering what you all think?
#3
Originally Posted by jwikoff99
How much boost did you have before? Is it possible you are running into this overboost protection I've heard about recently?
The other thing I thought it might be is a slipping belt. I am still using the stock belt and it does seem to be tight enough, but who knows.
#4
Junior Member
Posts like a Ricer Type-R
But you feel more power? You MUST have more boost then, and it'* just reading wrong. You wouldn't be the first to run into vacuum problems after pulling the SC, Gord. I did, a couple others, too.
How much more power do you feel? 5-10 hp is about the threshold for 'feeling' it. Did you use the sealant on both parts of the sc? I mean BOTH sides of the gear section? So it sealed the rotor casing too?
How much more power do you feel? 5-10 hp is about the threshold for 'feeling' it. Did you use the sealant on both parts of the sc? I mean BOTH sides of the gear section? So it sealed the rotor casing too?
#5
Originally Posted by willwren
But you feel more power? You MUST have more boost then, and it'* just reading wrong. You wouldn't be the first to run into vacuum problems after pulling the SC, Gord. I did, a couple others, too.
How much more power do you feel? 5-10 hp is about the threshold for 'feeling' it. Did you use the sealant on both parts of the sc? I mean BOTH sides of the gear section? So it sealed the rotor casing too?
How much more power do you feel? 5-10 hp is about the threshold for 'feeling' it. Did you use the sealant on both parts of the sc? I mean BOTH sides of the gear section? So it sealed the rotor casing too?
Tomorrow I will do so more tests to see exactly how it reacts. I will also triple check my connections.
Thanks for all the posts on how to do this too by the way Willren. A year ago I could barely do my own brake job but now I can tear apart the upper part of the engine without freaking out. Thanks.
#6
I did a little reading on ClubGP and found a few interesting threads concerning this. No answers but a few more good questions.
http://www.clubgp.com/newforum/tm.as...ode=&smode=&*=
http://www.clubgp.com/newforum/tm.as...anguage=single
http://www.clubgp.com/newforum/tm.as...ode=&*=#599532
http://www.clubgp.com/newforum/tm.as...mode=&*=#31078
Could it be something to do with intake preassure vs */C preassure? Leaking vacum line (checked them already but...)? Poor boost gauge reading?
If I get time this week I will try to vacum test my lines and see if my scanner can give me anything useful for this.
http://www.clubgp.com/newforum/tm.as...ode=&smode=&*=
http://www.clubgp.com/newforum/tm.as...anguage=single
http://www.clubgp.com/newforum/tm.as...ode=&*=#599532
http://www.clubgp.com/newforum/tm.as...mode=&*=#31078
Could it be something to do with intake preassure vs */C preassure? Leaking vacum line (checked them already but...)? Poor boost gauge reading?
If I get time this week I will try to vacum test my lines and see if my scanner can give me anything useful for this.
#7
Junior Member
Posts like a Ricer Type-R
**** you have a good one. I'll poke around some more on this. Fuddyduddy, you have any thoughts on this?
I know your new exhaust will have a negative effect on the indicated boost to some extent, but it should've been minor, and you would have noticed it already. I'm wondering if you might have gotten some debris lodged in a vacuum line during the rebuild?
Maybe yank all the lines one by one and blow them out. I'd tell you to swap gauges with someone else, but that would be kinda a BITCH!
I know your new exhaust will have a negative effect on the indicated boost to some extent, but it should've been minor, and you would have noticed it already. I'm wondering if you might have gotten some debris lodged in a vacuum line during the rebuild?
Maybe yank all the lines one by one and blow them out. I'd tell you to swap gauges with someone else, but that would be kinda a BITCH!
#8
Well, Not sure what is happening now but the gauge is starting to read up to about 9 PSI. It didn't just snap to it but it has been slowly climbing to it since I did the upgrade / repair. So it might just reach the 10+ PSI mark yet.
#9
Well, I am getting the needle up to almost 10 psi still, but I noticed one thing. Today I was taking off around a corner and just punched it. The needle slammed up to 9 psi or so and then fell back down to about 8 psi and maintained it (with slight fluctuation). When it dropped I could actually feel power go away. It was still fast as hell but I can tell there is so much more there that I haven't / can't tap yet. I think what is going on is this:
http://www.bonnevilleclub.com/forum/...pic.php?t=3605
http://www.bonnevilleclub.com/forum/...pic.php?t=3605
Thread
Thread Starter
Forum
Replies
Last Post
Toddster
Trouble shooting + Test Procedures
0
03-21-2009 06:24 PM
bigsteviejoe
Performance, Brainstorming & Tuning
12
09-05-2006 01:31 PM