On my last thread the fine people of this forum helped me identify my pulley size. Now Im wondering if 10lbs at WOT is normal because it seems lower than expected. Here are a list of modification and maybe somebody can put together an idea of whats going on.

Mods:
15% pulley
Alta 2% overdrive pulley
ebay large intercooler
silicone intercooler boots
alta air intake
straight pipe from cats back
msd ignition
1 step colder ngk plugs

bypass valve is stock. I tested the springyness of it and its easy to push in but pops back into position. I will be changing for a detroit tuned just incase.

Edit: I wanted to add a link to a video I took of the car at idle and under boost.

 

I've read a lot of posts on here about pulley size, but no one usually talks about how much boost pressure they actually run. Id wager its mainly because R53s never came with a boost gauge, as far as I know.

 

On my R53, I run a 15% pulley, CAI, colder plugs, 380cc injectors and a tune. I routinely get 15 lbs of boost at WOT measured with a Bluetooth dongle/OBD II Fusion app on my iPhone.

 

Yea I know not too many guys run a boost gauge. But I feel like this doesnt make sense unless my boost gauge is bad? But I doubt that honestly.

 

for me with almost the same setup minus the tune (coming soon) and 380cc injectors (delivered today) im getting between 10-12 psi at wot. I do have the smallest vacuum leak somewhere and I only get a CEL after a long drive after parking. Otherwise it runs great. Maybe my belt is slipping? Too stretched.

 

I get a little over 16lbs of boost at wot.

 

I know the DV is not closing fully on the one with a boost gauge amd it only makes 10, (no CEL) so yeah, you’ve got an issue somewhere imo.

 

At idle, check for unmetered air leak by judicious spray of starting ether around IC boots, fuel pressure regulator, etc. If rpm goes up, there's the leak. Belt slipping could very well be the culprit. Check your tensioner tab. Can you see the indicator hole? How old is the belt?

 

Well - I beg to differ. After installing my mechanical boost gauge (a second one. first one was bad), it was reading accurately = 17-18hg @Idle / 15psi @WOT, for a couple of days. Soon after, I noticed that at idle the gauge was reading between 13-10hg*(I think I wrote that right?) and only boosting 10-12psi max.
Although the car ran fine - this to me was a clear indication of a vacuum leak. Sure enough I discovered the brand new, cheap Dorman "Y" connector under the right side SC horn had completely snapped.
I like mechanical stuff oppose to digital (for some things), but - I for one am glad I took the time to install one.
Now that my new clutch is at its 680mi break-in, I thoroughly enjoyed twisting the revolution counter past 6,000 rpms today and once again, enjoyed watching that needle hover just above the 16psi mark. Just for the thrill of it if not for a brief moment.
It's the end of the month and the cops seem to be around every corner.

I guess my point is (for me), I have a fair grasp and understanding of general mechanics but in this case if it wasn't for this gauge - I would have probably never been aware that anything was wrong.

 

i think i remember at one point peaking at 15 almost a year ago

 

i agree with you 1 billion percent. Heres the thing though. I maintain 15-18hg at idle which i think is normal. Im starting to think my belt is old and slipping. The new 19% pulley and belt from WMW should fix that!

 

And possibly not the optimal size for the current pulley combination. Might also check the tensioner and idler pulley for wear or just replace given mileage on the car. Mine had only 71K and weren't roasted but they were getting there.

 

Put back on ur stock intercooler and you'll be back to 13-14lb of boost.. GET RID OF THAT USELESS , POWER ROBBING INTERCOOLER. You absolutely have no need for it and your only loosing power IF it's not a gp intercooler, grs motorsport or alta oversized ( trust me, ive tested 1st hand about 8x different style and brand intercoolers )...
you'll also gain back throttle response
the ebay ic restricts aur flow and you loose boost. THATS why your seeing cooler iat with it.. its cut your boost down and restricting the flow so much that that less air is moving through creating that much less heat..
I promise PROMISE if you put back on stock intercooler you'd feel the instant improvement.
I'm running a stock ic with 19% pulley and even in summer heat , the car makes 16-17psi. And peak iat's arnt bad enough to where it begins to pull timing yet. I make More boost on colder days even And that's with the m45 sc , stock head and stock cam and stock intercooler.

 

>MiniManAdam advocating for stock...anything
Whuuut

 

because I bet you didn't put on your ebay intercooler yet... try stock and see your boost and power come back..please trust me..
I too was educated on this and began testing to see if that guy was rite ( devilZ ) and as usual, of course he was rite but i just wanted to see 1st hand how each type and style intercoolers effected our cars performance.

 

lol ...... you made my morning !
But if anybody knows anything about me or my build , ive been chasing every last hp I can.. I've tested numerous NUMEROUS different things and combos to see what ACTUALLY provides real world, on street gains. Not some bs claims or 1x dyno pull that would NEVER be replicated on the street...
this is also why you don't see me selling bmw v12 tbody and intakes anymore , though they make MORE boost and a higher tq and hp # , the air velocity drop in your intake causes too much of a loss down low for it to equal out or justify the gains you get uptop..
atleast with the sprintex and m45 supercharger it doesn't. I WILL try the bmw v12 tbody and full 3in intake again on my tvs IF I end up getting the tvs..
unfortunately misinformation seems to spread and stick more than facts....
PEOPLE ! PLEASE GET RID OF YOUR EBAY INTERCOOLERS , theyre doing NOTHING but robbing your boost and throttle response. Dont believe me ? Go take your car for a good hard drive , then put back 9n ur stock ic and go do the same exact drive and see how much better the car feels with stock ic.

 

I will locate a better intercooler. However last year when i hit 15psi it was on this ebay intercooler. (Correction its a racing dynamics intercooler) But i do believe you and will order a better intercooler as I dont have the stock one anymore. Whats the best aftermarket one?

 

the ONLY ic's that actually provide gains are : grs ( has to be the motorsport or charge cooler version) , alta oversized ( good luck finding one ) , oem GP intercooler ( good luck finding one ) and defenders of speed ( again , good luck )...
if your not gonna drop the coin for a grs motorsport, just buy a used stock one off ebay with an intercooler cover ( covers actually does help )...
don't buy into the misconception that you need to upgrade your intercooler.. like i said. My setup is far more aggressive than yours and my stock ic has no problem dealing with iat's..

 

awesome info! I was already eyeing the grs motorsport intercooler. This sealed the deal for me I will order it. I will get this p1498 code sorted out first though. Seems to be plaguing me no matter what I fix or replace.

 

Although you may have already come across this thread...If not - Check out this post regarding p1498.
It seems to me you may have some related belt and harmonic balancer issues which may be affecting your boost (?).
However I believe you mentioned having an ATI crank balancer/pulley (?) - so I'm not sure if those are prone to fai or come loose.

 

Here's the motorsport version on my aero mini
and the chargecooler version on my other fully built mini.
You will be very impressed with the grs motorsport v the ebay , it will be a instant performance gain you'll be able to feel immediately. I promise. BUT you HAVE to get the motorsport version with the built in air diverters, those are what really help, plus it's different style core.
i havent tested a gp personally but i did read whete someone tested the grs motorsport ic vs a gp amd it experienced 0 boost loss.. vs a stock ic it only looses about 1-1.5psi only but yet cools better even than the ebay ic.
the chargecooler has been the ONLY ic I've tested that actually makes more boost than stock. I'm making 19psi with it and my sprintex WITH a bvh and cam too !
unfortunately I spent almost 2000$ on the chargecooler since I choose not to get it with its standard plumbing , i made a huge 2x pump cooling system for it so it runs hella efficient.

 

I have been following you yt so im familiar with the the ic you have installed on your grey mini. I always did wonder why two pumps and not just one strong enough?

 

One might be strong enough , I didn't try. Just better safe than sorry.
it's a pretty large volume of liquid with long large diameter hoses so it was more precautionary than anything really.
the car definitely has no heat issues, thats fir sure.
I'm hoping the tvs Im praying to get , im hoping thatll too help things run cooler. Because though the sprintex makes gobs of power, its a fricken heater upper , thats for sure. Stock ic I could see 160'F on long hard pulls for a max iat , yea it was only at 160 for a second but regardless, it peaked there and was pulling timing with that high of iat then.
I actually wished I hadn't sold my grs motorsport ic but I'd needed the cash then for something else unfortunately.
I'm sure I will buy another one eventually though...