Single Turbo vs Twin Turbos - BMW 1 Series Coupe Forum / 1 Series Convertible Forum (1M / tii / 135i / 128i / Coupe / Cabrio / Hatchback) (BMW E82 E88 128i 130i 135i)

Bimmer13 · 11-29-2012, 08:57 PM

Of the many cars I've had my last car was a Mazdaspeed3 Single Turbo. In that car you could REALLY feel the turbo. In the 135i I can barely feel the turbos. Is that because its 2 smaller turbos vs 1 bigger one? Also a BOOST gauge in the 135i would've been nice. But maybe since you can't really feel the turbos in the 135i that's why it doesn't have a gauge?

Thoughts?

Stohlen · 11-29-2012, 09:11 PM

You're not feeling the boost in your speed3... you're feeling the lack of it.

Turbo lag is the feeling you are getting, the time when you push the pedal down, and there is nothing until all of a sudden you're thrown back in your seat because the turbo finally comes on. The twin turbo has significantly less lag because there are two smaller turbos rather than one large one to create the desired effect. Since there is less lag, there is more power initially when you put your foot down, and thus less of that feeling as the turbo spools up to more boost.

^This is the very short answer.

Most turbo vehicles dont have a boost gauge. For the average driver it isn't necessary, so most oem's dont include it. Its added cost for little gain more than a novelty item because most oem boost gauges aren't made very accurate.

splitsecond · 11-29-2012, 09:59 PM

Quote:

Originally Posted by Stohlen

You're not feeling the boost in your speed3... you're feeling the lack of it.

Turbo lag is the feeling you are getting, the time when you push the pedal down, and there is nothing until all of a sudden you're thrown back in your seat because the turbo finally comes on. The twin turbo has significantly less lag because there are two smaller turbos rather than one large one to create the desired effect. Since there is less lag, there is more power initially when you put your foot down, and thus less of that feeling as the turbo spools up to more boost.

^This is the very short answer.

Most turbo vehicles dont have a boost gauge. For the average driver it isn't necessary, so most oem's dont include it. Its added cost for little gain more than a novelty item because most oem boost gauges aren't made very accurate.

^Exactly.

If you look at BMW's sales and service documentation, they make a huge deal out of the fact that you can't "feel" the turbo. The idea is that you should feel the full power band at the lower RPM's, and the car should respond like a naturally aspirated engine.

When you "feel" the turbo kicking in, that just means that you didn't have enough boost at the lower end.

Bimmer13 · 11-29-2012, 10:39 PM

Thanks for the replies. Makes sense however a boost gauge is more than a novelty. The 135i can't be in FULL BOOST the entire RPM range. It would be helpful if I could visually see when the Turbo's are in full boost.

christopherkriens · 11-29-2012, 11:02 PM

Quote:

Makes sense however a boost gauge is more than a novelty..

It's more than a novelty to enthusiasts, for sure. But we're the exception; the average BMW Owner probably doesn't know or care what it is. Betty the soccer mom with her new 328i sedan doesn't care how much BEwst she's running.

splitsecond · 11-29-2012, 11:07 PM

Well, she wouldn't be running any boost in a 328i. But yeah, I agree with your point.

Greenkirby21 · 11-29-2012, 11:09 PM

Quote:

Originally Posted by splitsecond

Well, she wouldn't be running any boost in a 328i. But yeah, I agree with your point.

the new 328i have a turbo 4... and I believe u can access the boost gauge through iDrive, at least I think my mom's 335i does that. If not boost, I know it tells you HP and Torque

GerryL · 11-29-2012, 11:10 PM

Quote:

Originally Posted by splitsecond

Well, she wouldn't be running any boost in a 328i. But yeah, I agree with your point.

She would if it were a new 4 cylinder turbo 328.

froop · 11-30-2012, 02:13 AM

Quote:

Originally Posted by Bimmer13

Thanks for the replies. Makes sense however a boost gauge is more than a novelty. The 135i can't be in FULL BOOST the entire RPM range. It would be helpful if I could visually see when the Turbo's are in full boost.

Go and get either a Procede or a JB4. You can change the dials on your instrument cluster to show the fuel gauge as a boost gauge. Each notch is 2.5 psi I believe so it shows up to a maximum of 20 psi.

pkim1079 · 11-30-2012, 02:55 AM

It def feels like a turbo to me.

Bmwbreed · 11-30-2012, 04:08 AM

Quote:

Originally Posted by Bimmer13

Thanks for the replies. Makes sense however a boost gauge is more than a novelty. The 135i can't be in FULL BOOST the entire RPM range. It would be helpful if I could visually see when the Turbo's are in full boost.

Well without a gauge you won't have the actual output number but according to BMW these engines make maximum torque from 1500rmp (1200 if n55) to the 5k range before power drops off. So theoretically it should be in full boost between those rpm numbers. This Is also why you can't quote feel the turbo. With full torque/boost output starting at such a low rpm there's really no time to anticipate it. It's just past idle basically

Stohlen · 11-30-2012, 09:29 AM

Quote:

Originally Posted by christopherkriens

It's more than a novelty to enthusiasts, for sure. But we're the exception; the average BMW Owner probably doesn't know or care what it is. Betty the soccer mom with her new 328i sedan doesn't care how much BEwst she's running.

Thats exactly what i just said

IZAGLO · 11-30-2012, 03:09 PM

I have to agree that a Turbo car should have a boost gauge for monitoring.... I had a Defi Boost gauge in my last car and loved it and now have the P3 Vent Boost gauge in my 135i which IMO is OEM looking and quality....amazing piece and should be standard on the 135i...it's that nice.
As far as "feeling" the boost like in a Speed3 or STI....yea, its the shitty lag of those cars your are feeling and then you get bombarded with boost from the turbo...it's fun for a bit but after a very short period the lag get's real old....The refinement of having 2 Turbo's and very little lag is really nice on the BMW ...

Bimmer13 · 12-02-2012, 11:47 PM

Quote:

Originally Posted by IZAGLO

I have to agree that a Turbo car should have a boost gauge for monitoring.... I had a Defi Boost gauge in my last car and loved it and now have the P3 Vent Boost gauge in my 135i which IMO is OEM looking and quality....amazing piece and should be standard on the 135i...it's that nice.
As far as "feeling" the boost like in a Speed3 or STI....yea, its the shitty lag of those cars your are feeling and then you get bombarded with boost from the turbo...it's fun for a bit but after a very short period the lag get's real old....The refinement of having 2 Turbo's and very little lag is really nice on the BMW ...

Exactly. Why wouldn't a turbo car have a gauge? If nothing else it give the driver more info about the car. Even if BMW claims that the car is in full boost from "idle" up to 5K RPM it still would be nice to see exactly where the motor and the turbos are at peak.

Stohlen · 12-03-2012, 02:23 AM

Quote:

Originally Posted by Bimmer13

Even if BMW claims that the car is in full boost from "idle" up to 5K RPM it still would be nice to see exactly where the motor and the turbos are at peak.

Where have they claimed that?

flinchy · 12-03-2012, 05:01 AM

Quote:

Originally Posted by Stohlen

Where have they claimed that?

yeah.. cos it's not.. it's like 2k ish boost STARTS.. then 3k is full boost or so?

Bmwbreed · 12-03-2012, 06:47 AM

Quote:

Originally Posted by Stohlen

Quote:

Originally Posted by Bimmer13

Even if BMW claims that the car is in full boost from "idle" up to 5K RPM it still would be nice to see exactly where the motor and the turbos are at peak.

Where have they claimed that?

He's probobly referring to my post where I said that BMW rates the engines being capable of 300lbs of tq from 1500 rpm up to the 5k range. At least that's what the graph shows in the brochure on the page with engine info. Then I said that's why there's practically no lag because not long past idle it's making the max tq that its rated at. So inbetween those numbers (1500-5000rpm) would be a good guess as to when it should be in full boost.

Bimmer13 · 12-03-2012, 09:16 AM

I think it's very interesting how nobody really KNOWS exactly when the car is at full boost yet BMW doesn't put a boost gauge on a blown car.

BTW yes I was referring to Bmwbreed post. I STILL don't know when the car is at full or partial boost.

Stohlen · 12-03-2012, 09:36 AM

Quote:

Originally Posted by Bmwbreed

He's probobly referring to my post where I said that BMW rates the engines being capable of 300lbs of tq from 1500 rpm up to the 5k range. At least that's what the graph shows in the brochure on the page with engine info. Then I said that's why there's practically no lag because not long past idle it's making the max tq that its rated at. So inbetween those numbers (1500-5000rpm) would be a good guess as to when it should be in full boost.

Just because a car is at max torque doesn't mean its at max boost. If your engine hit max boost at 1500 rpm, the engine would do nothing past 4000rpm.

Bmwbreed · 12-03-2012, 09:53 AM

Quote:

Originally Posted by Stohlen

Quote:

Originally Posted by Bmwbreed

He's probobly referring to my post where I said that BMW rates the engines being capable of 300lbs of tq from 1500 rpm up to the 5k range. At least that's what the graph shows in the brochure on the page with engine info. Then I said that's why there's practically no lag because not long past idle it's making the max tq that its rated at. So inbetween those numbers (1500-5000rpm) would be a good guess as to when it should be in full boost.

Just because a car is at max torque doesn't mean its at max boost. If your engine hit max boost at 1500 rpm, the engine would do nothing past 4000rpm.

I never said it was at max boost that entire time. Just somewhere inbetween that rpm range. You always seem to read very literal into what someone says in a thread. Lighten up bro.

bradleyland · 12-03-2012, 10:45 AM

Quote:

Originally Posted by Bimmer13

Thanks for the replies. Makes sense however a boost gauge is more than a novelty. The 135i can't be in FULL BOOST the entire RPM range. It would be helpful if I could visually see when the Turbo's are in full boost.

In what way would it help? What is the benefit of knowing your boost level in a stock car? Once you're modded, I totally understand, but stock, I just don't see the benefit.

Peak boost is not necessarily peak power (horsepower). Peak boost will often correspond with peak force (ft-lbs/newton-meters), but if you're driving for performance, you're more interested in power band and power peak.

If you're interested in knowing where your engine performs best, go do a dyno run. They're usually pretty cheap. If you're running stock, you can just Google image search for 135i N55 dyno and browse the results to get a feeling for where your car is making power.

If you're drag racing, you're most interested in determining shift points. Those are based on acceleration profiles for each gear. Peak acceleration should occur with peak power, so once you have a dyno, you know your shift point (or roughly). With a turbo car, you can sometimes benefit from short shifting a bit. If you really want to know, you get an accelerometer app for your smartphone, and you datalog an acceleration run in each gear. You combine the plots, and you look for the cross-overs. That's your shift point.

flinchy · 12-04-2012, 06:31 AM

a boost gague is more useful for diagnosing issues, if you're not hodling boost smoothly, or not hitting targets, you can clearly see it on a gauge...

also, due to how gearing works, acceleration at redline relative to in a higher gear should pretty much always be better.. unless your car REALLY tapers off badly.

all you have to look out for is don't hit the limiter, as the car retards and loses LOTS of power and acceleration.

11-29-2012, 08:57 PM	#1
Bimmer13 New Member Drives: 2010 BMW 135i Join Date: Nov 2012 Location: United States Posts: 22 iTrader: (0)	Single Turbo vs Twin Turbos Of the many cars I've had my last car was a Mazdaspeed3 Single Turbo. In that car you could REALLY feel the turbo. In the 135i I can barely feel the turbos. Is that because its 2 smaller turbos vs 1 bigger one? Also a BOOST gauge in the 135i would've been nice. But maybe since you can't really feel the turbos in the 135i that's why it doesn't have a gauge? Thoughts?
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11-29-2012, 11:07 PM	#6
splitsecond Space Admiral Drives: 135i Join Date: Sep 2012 Location: Chicago Posts: 307 iTrader: (1) Garage List 2008 BMW 135i [0.00]	Well, she wouldn't be running any boost in a 328i. But yeah, I agree with your point. __________________ 2008 135i Montego Blue sport pkg, premium pkg, Logic 7 sound, iDrive/Nav Mods completed: JB4+ & FBO \|\| LSD \|\| BMW-P suspension + F/R sway bars \|\| 18" Breyton GTS-R \|\| M3 front bushings \|\| Vogtland camber plates \|\| BMW-P rotors + Stoptech pads \|\|\|\| Acquired, not installed: BMS WW Meth kit \|\| Logic HVI intake \|\| Mishimoto OCC \|\|\|\| Shopping for: Summer tires

11-30-2012, 02:55 AM	#10
pkim1079 Lieutenant Colonel Drives: e90 ///M3 ZCP + e82 135i DCT Join Date: Dec 2009 Location: lost angeles Posts: 1,654 iTrader: (0)	It def feels like a turbo to me. __________________ 1,2,3,4,5,6,7,8.3 shift! (repeat!!) who needs software when you can tune the DRIVER?

11-30-2012, 03:09 PM	#13
IZAGLO Mbira Drives: Sedonna Red 09 135i SOLD Join Date: Jan 2010 Location: Garage cleaning Brake Dust Posts: 923 iTrader: (3)	I have to agree that a Turbo car should have a boost gauge for monitoring.... I had a Defi Boost gauge in my last car and loved it and now have the P3 Vent Boost gauge in my 135i which IMO is OEM looking and quality....amazing piece and should be standard on the 135i...it's that nice. As far as "feeling" the boost like in a Speed3 or STI....yea, its the shitty lag of those cars your are feeling and then you get bombarded with boost from the turbo...it's fun for a bit but after a very short period the lag get's real old....The refinement of having 2 Turbo's and very little lag is really nice on the BMW ... __________________

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11-29-2012, 09:11 PM	#2
Stohlen Captain Drives: AW 135i Join Date: Aug 2012 Location: Waterford, Mi Posts: 600 iTrader: (1) Garage List 2008 BMW 135i [4.00]	You're not feeling the boost in your speed3... you're feeling the lack of it. Turbo lag is the feeling you are getting, the time when you push the pedal down, and there is nothing until all of a sudden you're thrown back in your seat because the turbo finally comes on. The twin turbo has significantly less lag because there are two smaller turbos rather than one large one to create the desired effect. Since there is less lag, there is more power initially when you put your foot down, and thus less of that feeling as the turbo spools up to more boost. ^This is the very short answer. Most turbo vehicles dont have a boost gauge. For the average driver it isn't necessary, so most oem's dont include it. Its added cost for little gain more than a novelty item because most oem boost gauges aren't made very accurate.

11-29-2012, 10:39 PM	#4
Bimmer13 New Member Drives: 2010 BMW 135i Join Date: Nov 2012 Location: United States Posts: 22 iTrader: (0)	Thanks for the replies. Makes sense however a boost gauge is more than a novelty. The 135i can't be in FULL BOOST the entire RPM range. It would be helpful if I could visually see when the Turbo's are in full boost.

12-03-2012, 09:16 AM	#18
Bimmer13 New Member Drives: 2010 BMW 135i Join Date: Nov 2012 Location: United States Posts: 22 iTrader: (0)	I think it's very interesting how nobody really KNOWS exactly when the car is at full boost yet BMW doesn't put a boost gauge on a blown car. BTW yes I was referring to Bmwbreed post. I STILL don't know when the car is at full or partial boost.

12-04-2012, 06:31 AM	#22
flinchy Lieutenant Colonel Drives: 130i Join Date: Nov 2011 Location: QLD, Australia Posts: 1,837 iTrader: (0)	a boost gague is more useful for diagnosing issues, if you're not hodling boost smoothly, or not hitting targets, you can clearly see it on a gauge... also, due to how gearing works, acceleration at redline relative to in a higher gear should pretty much always be better.. unless your car REALLY tapers off badly. all you have to look out for is don't hit the limiter, as the car retards and loses LOTS of power and acceleration.