Boost Levels At Steady Speed - BMW 1 Series Coupe Forum / 1 Series Convertible Forum (1M / tii / 135i / 128i / Coupe / Cabrio / Hatchback) (BMW E82 E88 128i 130i 135i)

DBoyBimming · 12-30-2012, 11:26 PM

Whats up guys, Just wanna hear some feedback on what your boost reads while your at steady throttle. My AP is always reading about 1-2 lbs even at 60mph steady throttle. Is this normal? Thanks!

1911A145 · 12-31-2012, 12:11 AM

pretty normal.

Dan-12TTRS · 12-31-2012, 03:10 AM

Technically..... If your at a steady rate of speed you will register zero boost. There are pluses and minuses due to the cars not bein perfect. But if your not loading the throttle, you are not boosting.

Adam135 · 12-31-2012, 04:07 AM

Normal

RimasRS · 12-31-2012, 06:18 AM

For me it was also interesting why it does not go to vacuum.

But I think it is bad reading of the AP

DBoyBimming · 12-31-2012, 05:07 PM

Ok, just making sure its norm for this car. My Mazdaspeed was always at 0psi unless I was giving some forward throttle. Thanks for the feedback guys! Was thinking the waste gate was having issues.

Em/1 · 12-31-2012, 05:28 PM

Quote:

Originally Posted by Dan-12TTRS

Technically..... If your at a steady rate of speed you will register zero boost. There are pluses and minuses due to the cars not bein perfect. But if your not loading the throttle, you are not boosting.

That doesn't make any sense to me; if your speed is low, then low throttle opening and low exhaust speed and likely negative manifold pressure. If you are doing 140, there will be boost!

Dan-12TTRS · 12-31-2012, 08:07 PM

If you are doing 140 an not accelerating, ther is NO BOOST, as you are not forcing any more air, besides natural atmospheric pressure there is no extra into the manifold.

Pig Farmer · 12-31-2012, 09:44 PM

For what it's worth, I see a slight vacuum on the highway unless accelerating.

Dan-12TTRS · 01-01-2013, 02:13 AM

Right, that's normal, unless something is wrong there should be no positive boost when not on throttle.

Em/1 · 01-01-2013, 09:35 AM

Quote:

Originally Posted by Dan-12TTRS

Right, that's normal, unless something is wrong there should be no positive boost when not on throttle.

OK, maybe I should have said "top speed". Even at 70mph you are only using about 10% of engine peak power. Once the power required to maintain speed exceeds that which the engine can produce with no boost, you will have boost at a steady speed as long as the power required is high. Certainly you can see that at top speed, even tho "steady" you will be at maximum boost for that engine rpm (otherwise, your speed would increase!!) At normal highway speeds you will not see this effect!

ozinaldo · 01-01-2013, 12:36 PM

Quote:

Originally Posted by DBoyBimming

Whats up guys, Just wanna hear some feedback on what your boost reads while your at steady throttle. My AP is always reading about 1-2 lbs even at 60mph steady throttle. Is this normal? Thanks!

It's because the car doesn't want you to go at steady throttle, just another hidden gem

12-30-2012, 11:26 PM	#1
DBoyBimming New Member Drives: BMW 135I Coupe Join Date: Dec 2012 Location: Towson, MD Posts: 9 iTrader: (0)	Boost Levels At Steady Speed Whats up guys, Just wanna hear some feedback on what your boost reads while your at steady throttle. My AP is always reading about 1-2 lbs even at 60mph steady throttle. Is this normal? Thanks!
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12-31-2012, 12:11 AM	#2
1911A145 Lieutenant Drives: 135i Join Date: Mar 2012 Location: Florida Posts: 539 iTrader: (2)	pretty normal.

12-31-2012, 03:10 AM	#3
Dan-12TTRS Banned Drives: 12 Phantom Black Audi TTRS Join Date: Dec 2012 Location: Glendale AZ Posts: 28 iTrader: (0)	Technically..... If your at a steady rate of speed you will register zero boost. There are pluses and minuses due to the cars not bein perfect. But if your not loading the throttle, you are not boosting.

12-31-2012, 04:07 AM	#4
Adam135 Lieutenant Drives: 2009 135i Join Date: Oct 2011 Location: USA Posts: 590 iTrader: (2)	Normal

12-31-2012, 06:18 AM	#5
RimasRS Lieutenant Colonel Drives: 135i MT 2009 AW Join Date: Sep 2010 Location: Europe Posts: 1,668 iTrader: (0)	For me it was also interesting why it does not go to vacuum. But I think it is bad reading of the AP

12-31-2012, 05:07 PM	#6
DBoyBimming New Member Drives: BMW 135I Coupe Join Date: Dec 2012 Location: Towson, MD Posts: 9 iTrader: (0)	Ok, just making sure its norm for this car. My Mazdaspeed was always at 0psi unless I was giving some forward throttle. Thanks for the feedback guys! Was thinking the waste gate was having issues.

12-31-2012, 08:07 PM	#8
Dan-12TTRS Banned Drives: 12 Phantom Black Audi TTRS Join Date: Dec 2012 Location: Glendale AZ Posts: 28 iTrader: (0)	If you are doing 140 an not accelerating, ther is NO BOOST, as you are not forcing any more air, besides natural atmospheric pressure there is no extra into the manifold.

12-31-2012, 09:44 PM	#9
Pig Farmer Lieutenant Drives: 2009 BMW 135i Join Date: May 2010 Location: Florida Posts: 487 iTrader: (0)	For what it's worth, I see a slight vacuum on the highway unless accelerating.

01-01-2013, 02:13 AM	#10
Dan-12TTRS Banned Drives: 12 Phantom Black Audi TTRS Join Date: Dec 2012 Location: Glendale AZ Posts: 28 iTrader: (0)	Right, that's normal, unless something is wrong there should be no positive boost when not on throttle.