So Iv been told that I'm missing 3psi.. On woot my car starts at 13psi then climbs up to 16psi as I go faster.. So my question is, is it suppose to hit 16 psi off the bat? Mods are rmw head race cam 550cc injectors exhaust headers intake.. I got a flash tune from Jan and I only got 115 whp.. I checked bpv even got a new one. Checked timing check compression engine has 90,000km's on it and I don't have any boost leaks ... I'm really at a lost don't know what ells I could check

 

The amount of boost depends on the pulley, the condition of the SC, and anything else done to the car to allow the air to flow....with a head, header, and exaust, you should have lower boost than car with few mods...in you case lower boost may be ok due to the fact it MAY be the result of lower resistance....add to the mix boost guages don't ted to be very accurate (they vary almost as much as dyno's), and if it feels strong...you might be fine.
part of your posting I did not understand....the dyno readings (reporting values) must be different in your area...

 

Remember, boost levels can only be directly compared on cars with similar intake/exaust mods....your car has "bigger" pipes with you mods....sou you flow more air at a slightly lower psi....this means less heat, more hp...and the possibility of running a bigger sc...to make more boost....

 

Sorry I forgot to mention I do have a 17% pulley. Also I went to a tune party that Jan was hosting. He said I was low thus the low hp numbers with all the mods I should have 240- 250 hp not 215. As for my mods Iv read alote of ppl have the same mods and are getting those numbers...

 

Since it was done at a tune party, and other mini's were tuned, run on the dyno, it makes the numbers more credible....215 is kinda low...but sometimes some motors just don't perform...and some seemingly similar or even less Modded motors make more.
It sounds like you have done the basics...but the boost might not be where the issue is..sure the sc could be worn...
What did Jan say...the graphs from the tune tell a story...along with any other info/tidbits of knowledge he had to add...like was it screaming for more fuel....did it seem like the belt was slipping..was the exaust flowing right.....etc.

 

what year is the car? what were the results of the compression test? I dont think the lower performance comes down to boost, could be any number of things, like zippy said, theres more to the story.

 

Well when I talked Yo Jan it was that boost everything ells seemed to be running good engine wise from what the dyno was saying. Like I said boost starts at 13 psi not at 16. Don't know. But I just want ti know how your boost starts on woot is it constant or is raises

 

Part of the issue (for low HP) might be the combo of a high rpm race cam, with a pulley made for low-mid rpm's....the 17% makes more heat than boost at higher rpm's....
remember...a ,motor is a system..all parts must be matched for best power, drivability and efficiency...thought must be put into choosing components so they complement each other...rather than fight one another!!
It goes without saying, check you couplers on the ic....they get kinda stiff after a few years....common source for leaks...new ones are about $50. Look for any streaks on the ic...this weeping oil would indicate a crack....
I guess it is also safe to assume all the other stuff is in good shape...plugs with less than 30,000 miles, jcw heat range, good clean air-filter, clean oil etc.

 

my boost def starts lower and then raises, I'm rarely on the throttle enough to make full boost but it's not 16PSI through the rev range.(checking through my datalogs to confirm)

think about it, the SC is spinning related to engine RPM, so lower down, it's not going to make as much boost as up high. sounds like its normal.

I've done some extended tuning sessions with jan and he never said anything to me about my boost building in any kind of off way. Have you given him a call directly to see what his thoughts are, I'm sure he had a LOT to do at a tune party, maybe he can give you a clearer idea of what it might be.

 

My boost gauge is metric (GReddy warning gauge). Typically I see .6-.7 BAR (8.7-10.15 PSI) at WOT (i.e. instant slam of throttle pedal) with lower RPMs (2-3K range). I don't hit 1.1 BAR until I get to 6500 RPM.

 

that was going to be my next guess with the intercooler and the couplers.. but what do you mean about the weeping oil. also i did change all those other things as well.. like i said im running down the line of all the things that would cause the problem..

 

Since the boosted air has trace amounts of oil in it from the pcv system, the oil tends to condense... (that is why occ cans are used, but it has a minimal performance impact on a gen1 car, the occ are mostly bling) and it tends to leak out and leave streaks on the ic if it is cracked...
the ic boots seem to be good for about 2 psi or so in many cases

 

your rite part way through when your everyday normal driving, its not going to be max boost... but when you floor it.. its suppose to be at a 15 or 16 psi off the bat depending on what type of pulley u have .. we do have a supercharger not a turbo.. boost is suppose to be constant... jan did take his time with the car we did a number of runs, so it was not a rush job

 

ill tape off one end of the intercooler and fill it with water to see if it leaks.. the couplers seem good to me not stiff or anything like that but it helps if i change them maybe they are worn out

 

sorry buddy, boost on a supercharger is Dependant on rotation, , they make full boost earlier than big turbos, but modern twin scroll turbos are why superchargers are not really used anymore, they do essentially as good of a job without the parasitic loss on the engine.

so I really think your hunting a ghost.

Keep in mind this is a roots type blower, not a twinscrew, so not 100% boost all the time, it is a more passive compressor.

please chime in if your making 15PSI at 2500 or even 3.5k RPMs././/.

 

Oh I didnt know that about the charger I thought they are all the same. But ya I'm not making that boost that that rpm once I hit 5.5 then it's 15 16. I really hope that I'm searching for a ghost lol but I dout it

 

if I slam on the accelerater doing normal driving it hits 9-10 psi instantly. you shouldn't be seeing 16 that soon it has to build up. your chasing a ghost!

 

That's not what Jan told me and he would know better then anyone of us... Also when i hit it it goes to 13 psi

 

lol, did you give him a call again to clarify? or you still going off a conversation from the tune party? I'm sure he would be happy to clear that up for you so you could get on to bigger and better things

this will also depend highly on the boost gauge your using(they tend to vary a bit on accuracy), all of my readings are off the ECU, a better reading would be from a real hard line gauge, but I dont have one yet.

 

How many miles on the car? If your HP numbers are that low I'd say your supercharger could be failing. But that's just my .02
Something to consider depending.....

 

Syms has a saying "an educated customer is our best consumer"

You could stand to do some reading so that the people working on your car don't take you for a ride.

 

lol, im sorry to bust your bubble, but jan is not a certified master mechanic, a certified bmw or mini mechanic, and not an authorized or licenced dealer for dimsport. He is a guy who got pissed at a tuner and M7 and decided to go into buisness on his own making "race parts", which is great, but doesnt say he KNOWS anything about how to fix a car.
boost in a supercharger IS supposed to hit instantaneously, but you have to realize, the compresser spins off of a pulley that is driven by the serpentine belt system, thus, the faster the engine spins, the faster the blower spins.. and since the blower moves air by rotating the rotors, tada, more boost is made at higher rpm's due to efficiency loss from the engine and a change in AFR at higher rpms so the engine in fact does not use as much air per bang.
In another sense, the supercharger spins faster, and even though the engine needs more air at a higher rpm, the supercharger works via creating back pressure in the system, forcing air into the cylinders, and this is done by providing "more" air than is needed. (if the other end of the super charger was open to atmosphere it would produce 14.7 psia aka 0 psig mathamatically, its the backpressure from the engine that creates the boost.
if you have ever taken a course in fuid dynamics or thermo for a chemical engineerign or mechanical engineering course, you can view the supercharger just like any other pump. It has a NPSHr in order for it not to cavitate, but until it reaches that level, the more volume you give it on the input and output sides power pressures on the pump, easing its work load and reducing the horsepower input to drive the pump, and the higher the rpm, the more air you move.
here is an example.
"head" is pressure, (it is in terms of feet of water insead of pounds per square inch) tdh is total dynamic head (or gauge pressure with 0 being intake pressure)
the flow rate of air (think air charge from a supercharger) is on the bottom, and the horsepower lines are diagonal down from left to right while the parabolic curves are efficiency lines.

In that curve you can see that to provide 20gpm you could either use a 4.5hp pump and deliver water at a pressure that could drive it to 80 feet above your water source, (im not going to get techincal on the npshr.. go take a fluids class if you want to learn everything, haha) OR you could drive water to 300 feet above your head using 7.5hp, but you would still only be delivering 20gpm. and the difference between these setups? restrictions (pipe size, bends, valvs, fittings, expansions/contractions and the like)
so the fact that your only showing X psi means nothing at first unless you are showing x psi next to someone who is showing x+3 with the EXACT same setup. now granted your numbers for modifications are low, but your boost actually seems about in line with a 15 % pulley, but is a bit low for a 17%.
You will need to remember though, the supercharger starts to cavitate with a 17 or a 19% in the upper rpm's (produce a lot more heat and increase pressure but move less air) so you actually loose a little top end hp, which is where hp numbers come from, while your tq values would be higher than someone with a 15 % (peak tq in our cars is usually ~3.5k rpm)
I realize this is a jumbled mess, but i did it at work while answering phones and im a bit ADD. haha. Its a complicated mess as to how all of this works mathamatically, but if you sit down and do it it makes perfect sense for your numbers to climb with rpm on a roots style blower.
if you want consistant boost to redline, get a r56. Their turbos are small enough that they will hit full, or close to full spool at or before 3k rpm's and will hold it to redline, but throttle responce is laggy and you will no longer have that iconic whine that i love.

 

So, can anyone else with a boost gauge installed indicate what their BAR/PSI value is when they go WOT starting at 2K RPMs? If you are concerned about gauge variations, anyone using a Scangauge II or other OBD-II port reader to find out?

 

2k 8lbs, 2.5k is 9-10 lbs. solid 10lbs by 3,200, and at redline in second ill hit 30 abs or 15.3psi occasionally, but usually see 28.8-29.4 on the scanguage (14.1-14.7)
15% pulley with 109k miles on the charger

 

OK, soccerbummer1104, that's comparable with mine at those lower RPMs. Some consistency sounds good.