BMW s35i vs s35is

[Constant.S]

So, does anyone know if it IS true that the 35is has a redesigned less restrictive Air-intake and has different DCT programing to make it more responsive and to have better rev-matching in upshifts?
I am asking because i have an appointment with my BMW's dealer chief mechanic this friday to retrofit/upgrade some parts on my Zed. No speculations please

[entrepreneur177]

That what i was thinking about....changing intake and downloading 35is soft to my 35i.....

[Constant.S]

Yeah, my BMW mechanic said its not an "official option" but he "can" do it. I just wanted some info about it before i go to them so i can search online to see if i can get the parts i need cheaper

[///carbon]

Originally Posted by Constant.S

Yeah, my BMW mechanic said its not an "official option" but he "can" do it. I just wanted some info about it before i go to them so i can search online to see if i can get the parts i need cheaper

waw, keep us updated. maybe also part numbers required...

[Silver-Bolt]

Not 100% certain but I believe the air box on the "i" and "is" are the same.

[Constant.S]

The iS on the other hand receives 340hp at 5,900 rpm from an even further tuned N54 engine architecture. Increased boost is responsible for the power jump, along with higher torque output: 332 lb-ft available from 1,500 rpm with an additional 37 lb-ft available for temporary boosts of acceleration bringing the total torque output to 369 lb-ft with foot-to-floor. This increased performance is secondary to a larger, free-flowing intake manifold, increased peak turbo boost, a new high-flow exhaust, and reworked engine management.
I've read about it in alot of magazines that the IS has a bigger airbox. This quote is from BMWBLOG.
source: http://www.bmwblog.com/2010/09/10/bm...4-sdrive-35is/

[Alext]

I have been researching this very thing. RealOEM shows that not only the intake is the same but also the (MORE importantly) the charge air suction piping, which is actually quite restrictive. Some guys on N54tech are looking at replacing it for gains of around 20whp!

The 35is also is supposed to have a lighter dual mass flywheel.

There is NO OFFICIAL information on the 35is from BMW which makes me suspicious. Who knows where these journalists are getting their info from?

The 335is actually does have a lighter flywheel to cope with the extra torque (this is the reason BMW have given) plus upgraded cooling etc.

[Constant.S]

20 whp from this intake? Sure if you threw a little itsy bit of nitrous in there lol Just too optimistic. 7-8whp sounds more like it The fuel consumption would be MUCH higher on the IS in comparison with the 35i if the "IS" intake manifold would be THAT much more less restrictive...
I believe about the lighter flywheel because of the torque with the overboost function. I just want the damn DCT software so i can move along and be in piece with my flash tune...

[Alext]

I think I was misunderstood. The guys are looking into developing different charge pipe tubing (the pipes that connect to the turbo and one side of the intercooler) as apparently that will give them the gains of 20whp. If you have a look it is a squarish shape on some N54 models and very restrictive.

[Constant.S]

Originally Posted by Alext

I think I was misunderstood. The guys are looking into developing different charge pipe tubing (the pipes that connect to the turbo and one side of the intercooler) as apparently that will give them the gains of 20whp. If you have a look it is a squarish shape on some N54 models and very restrictive.

Well the Intake manifold includes those pipes, but yea, i thought just replacing it with the IS stock
Well, i trully have no idea how much gains that kind of fabrication would have, and it needs alot of R&D to make air flow efficient and maximized in such a development. I wish them best of luck

[Silver-Bolt]

Intake manifold is not the same as the air intake box. I really doubt BMW developed a special intake manifold just for the "is" cars. The 35hp difference from the "i" tp the "is" is tuning and boost, nothing more. JB, Dinan, and others have proven that there is a ton more h/p with nothing more than tuning.

[Constant.S]

Originally Posted by Silver-Bolt

Intake manifold is not the same as the air intake box. I really doubt BMW developed a special intake manifold just for the "is" cars. The 35hp difference from the "i" tp the "is" is tuning and boost, nothing more. JB, Dinan, and others have proven that there is a ton more h/p with nothing more than tuning.

True but the DCT software is upgraded and thats a fact. Actually, when someone is adding power to a DCT vehicle, they SHOULD reprogram the DCT ecu to deliver the power more progresivly and work with downshifts/upshifts better in compliance with the new hp/torque rpm area of the engine (did that make sense? it did in my mind ). Thats what ESS does with the DCT e92 M3, they reprogram the DCT ecu also.

[Alext]

I wonder if it would be possible to go in for a service with a 35is and the dealer accidentally updates your software to the lower 35i spec haha?

[tranquility]

Originally Posted by Constant.S

The iS on the other hand receives 340hp at 5,900 rpm from an even further tuned N54 engine architecture. Increased boost is responsible for the power jump, along with higher torque output: 332 lb-ft available from 1,500 rpm with an additional 37 lb-ft available for temporary boosts of acceleration bringing the total torque output to 369 lb-ft with foot-to-floor. This increased performance is secondary to a larger, free-flowing intake manifold, increased peak turbo boost, a new high-flow exhaust, and reworked engine management.
I've read about it in alot of magazines that the IS has a bigger airbox. This quote is from BMWBLOG.
source: http://www.bmwblog.com/2010/09/10/bm...4-sdrive-35is/

OT but from the link, it states "That is not to say that the Z4 sDrive 35iS can’t handle! No, on the contrary we were impressed with the lateral grip this car is capable of. It’s not every day that you’ll find a sports car capable of lifting its inside wheel – and that is precisely what this stock Z4 is capable of! Don’t believe us? Pay closer attention to our cover photo and note the daylight showing underneath its front wheel."

Why is that a good thing?

[dcs2k]

just awesome if the DCT on the 35i can be reprogrammed

[teagueAMX]

Originally Posted by tranquility

OT but from the link, it states "That is not to say that the Z4 sDrive 35iS can’t handle! No, on the contrary we were impressed with the lateral grip this car is capable of. It’s not every day that you’ll find a sports car capable of lifting its inside wheel – and that is precisely what this stock Z4 is capable of! Don’t believe us? Pay closer attention to our cover photo and note the daylight showing underneath its front wheel."

Why is that a good thing?

I believe they were suggesting on the one hand they had difficultly inducing oversteer, which is what you see approximately mid-turn when the car's tail begins to swing out. Top Gear's Jeremy Clarkson and drifting competitors really love to play around with oversteer. For performance driving, drivers like to ride the knifes' edge on the limits of grip between understeer and oversteer. Understeer can be fixed with a stiffer rear sway bar (aka stabilizer bar) which acts like a lever arm to push some of the cornering force to inside wheel. You'll notice the car is leaning going through the turn.

On the other hand, you'll note from the photograph, as the car was accelerating out of the turn, it began to lift the front tire and you could see "daylight" under the tire. That result from a very car stiff frame, excellent lateral (sideways) tire grip and a lot of axle torque. Again, a stiffer sway bar would flatten the car's stance through the turn. Regardless, lifting the tire through the turn is pretty exceptional, especially considering the car doesn't have a limited slip differential.

Here's a couple of 'tube vids. The 1st one is humorous with Richard Hammond being dumb. The second one is a bit more informative with Tiff Needell

[skier219]

I'd say lifting a tire on an open roof car is extremely exceptional. That is an indicator that the body is very stiff indeed. Most cars of this type almost always have poor torsional stiffness, and are noodly enough that they won't be lifting tires regardless of other factors.

[tranquility]

Originally Posted by teagueAMX

I believe they were suggesting on the one hand they had difficultly inducing oversteer, which is what you see approximately mid-turn when the car's tail begins to swing out. Top Gear's Jeremy Clarkson and drifting competitors really love to play around with oversteer. For performance driving, drivers like to ride the knifes' edge on the limits of grip between understeer and oversteer. Understeer can be fixed with a stiffer rear sway bar (aka stabilizer bar) which acts like a lever arm to push some of the cornering force to inside wheel. You'll notice the car is leaning going through the turn.

On the other hand, you'll note from the photograph, as the car was accelerating out of the turn, it began to lift the front tire and you could see "daylight" under the tire. That result from a very car stiff frame, excellent lateral (sideways) tire grip and a lot of axle torque. Again, a stiffer sway bar would flatten the car's stance through the turn. Regardless, lifting the tire through the turn is pretty exceptional, especially considering the car doesn't have a limited slip differential.

Here's a couple of 'tube vids. The 1st one is humorous with Richard Hammond being dumb. The second one is a bit more informative with Tiff Needell

Thx, Tiff's video was quite informative.