[MD 335is]

I understand the 335is is capable of a short 6-7 sec overboost.
But how exactly does this work

- Is it only available in a continuous 7 sec?
- What's the reset time before it's available again?
- Is it only available under a certain RPM?
- Does switching gears loose the over boost?

[MD 335is]

nobody?

[ajeffrey]

It basically gives you up to 370 lb-ft of torque for 6-7 seconds when you stomp on it. The RPMs would need to spool up again followin an up-shift to re-engage the overboost. Def great for high-speed highway passing. The car rips.

[Eric335]

I didnt know that...very very cool

[MD 335is]

Originally Posted by ajeffrey

It basically gives you up to 370 lb-ft of torque for 6-7 seconds when you stomp on it. The RPMs would need to spool up again followin an up-shift to re-engage the overboost. Def great for high-speed highway passing. The car rips.

What do you mean the rps need to spool up again - how long does that take?

[rayainsw]

FWIW, in two test drives, I noticed absolutely no
interruption in acceleration on up-shifts w/DCT trans...
- Ray
335iS on order

Originally Posted by MD 335is

What do you mean the rps need to spool up again - how long does that take?

[ajeffrey]

Originally Posted by rayainsw

FWIW, in two test drives, I noticed absolutely no
interruption in acceleration on up-shifts w/DCT trans...
- Ray
335iS on order

I'm sure not. It's not like the car has interrupted acceleration, it's just that the overboost only lasts 7 secs and if you up-shift you need to get revs back up to have it kick in again. Not that it matters, the car pulls hard throughout the power band. I also have a 6mt, so the DCT is probably going to be even smoother....

[KevinJ]

The 335i has a turbo overboost of 8.7 PSI. The 335is ups this to 14.5 for (7-10 seconds). Recall that the 335i has a nominal boost of 5.5psi with a max of 8.7psi. The 335is has a nominal of 11.6 with a max of 14.5.

The overboost happens under certain load conditions or such as sudden or hard acceleration. Further reports that emphasize this: "temporary peak torque of 370 lb-ft is available under special high-load circumstances, such as when overtaking at higher speeds." Under load the boost is upped from 11.6 to 14.5 in higher gears for up to 7-10 seconds.

Further according to BMWUSA.com "electronically-controlled overboost function to briefly increase torque under full load by another 37 lb-ft.". According to BMW the temporary 37ft lb torque is delivered through the "standard turbo boost function".


"The 335is comes packing 320hp at 5,900 rpm and 332lb-ft of torque is available from 1,500-5,000 rpm. The engineers have tweaked the twin-turbo 3-liter motor to have an overboost function that increases torque to 370lb-ft. The overboost function comes into play at higher engine speeds and gears, similar to that of the Z4 sDrive35is."

The early reports of the 335is said 7 second overboost reported by BMW. There are a few other reports of 10 seconds of overboost.

You can see the overboost on the torque dyno below. It would be nice for someone to hack it so it boosts to redline!

Originally Posted by MD 335is

I understand the 335is is capable of a short 6-7 sec overboost.
But how exactly does this work

- Is it only available in a continuous 7 sec?
- What's the reset time before it's available again?
- Is it only available under a certain RPM?
- Does switching gears loose the over boost?

[sneaks]

I don't think the turbos are big enough to provide enough air flow at high rpms regardless of overboost or not. I think the only limiting factor for full boost at all times is heat soak.

[FoShizzle]

Originally Posted by KevinJ

The 335i has a Turbo boost of 8.7 PSI. The 335is ups this to a normal 11.6 psi and a overboost of 14.5 for (7-10 seconds) under 4500 RPM. Basically they don't want the 335is to out-run an M3 if they kept the boost up to redline.

The overboost happens when you press the accelerator into "kick-down" or essentially flooring it. The "kick-down" is the notch in the accelerator before it hits the floor.

The early reports of the 335is said 7 second overboost reported by BMW. There are a few other reports of 10 seconds of overboost.

You can see the overboost on the dyno below which proves that it cuts out at 4500rpm. It would be nice for someone to hack it so it boosts to redline!

Good info. Although, I'm nearly positive that hitting the kickdown isn't required for overboost. I'll do a log of stock boost and post it up when I get a chance. As far as overboosting to redline... No bueno - at least not yet. The DCT doesn't like it. Ive got the JB4 on my 335is and in order for shifts to be smooth(ish), boost needs to taper to (near) stock level at the redline shift.

[tunachris]

I thought that the JB4 overrides the the overboost function on a 335is?

[FoShizzle]

You could look at it that way OR you could say that it's UNLIMITED overbost.

[KevinJ]

After reviewing more information, I don't think "kick-down" is required. I found from BMW that the boost is standard, they just up'ed it for the 335is.

Originally Posted by FoShizzle

Good info. Although, I'm nearly positive that hitting the kickdown isn't required for overboost. I'll do a log of stock boost and post it up when I get a chance. As far as overboosting to redline... No bueno - at least not yet. The DCT doesn't like it. Ive got the JB4 on my 335is and in order for shifts to be smooth(ish), boost needs to taper to (near) stock level at the redline shift.

[KevinJ]

See this thread which has an official BMW press kit dyno for the mini cooper s which has the same turbo numbers as the 335is: 11.6 nominal and 14.5 overboost, pretty interesting:

http://blogs.insideline.com/roadtest...overboost.html

[michaelalex17]

what i dont unserstand is a jb3 on map 5 makes the same boost but it makes less power? but at the same time a jb3 335i could beat a 335is. i dont get how this works?

[KevinJ]

I suspect that the more aggressive after market fuel injector rates and air ratio adjustments come into play. I think the difference would be after market would make 40hp and 20tq more than the 335is.

The 335is however has stock software backed by a manufacturer warranty and the cooling bits to support the increased HP/Tq (additional oil cooler, water, and larger fan).

Originally Posted by michaelalex17

what i dont unserstand is a jb3 on map 5 makes the same boost but it makes less power? but at the same time a jb3 335i could beat a 335is. i dont get how this works?

[michaelalex17]

"I think the difference would be after market would make 40hp and 20tq more than the 335is."

so your saying a jb3 has 40 more horsepower then 370 horsepower? it doesnt. on map 5 it makes like 330 horsepower or something like that, and it beats a car with 370 horsepower.

[KevinJ]

The jb3 would make about 340hp on the dyno for the dyno numbers I saw. "370' is the 335is torque number. On the dyno the 335is makes about 340tq where the jb3 would make around 360tq.

You have it wrong, the jb3 would be making more hp/tq than a 335is on the dyno and would beat a 335is. Overall the jb3 would be +40 hp and +20 tq over the 335is. I also saw it stated that adding aftermarket software to the 335is it doesn't perform any better than a 335i with software.

The issue is that the extra power likely adds stress on a standard 335i from all the heat which is why BMW gave the 335is an extra oil and water cooler and a larger fan. Also the aftermarket software is not tuned by BMW certified engineers that have full access to the engine management. So how much of that large boost is usable until the engine blows up...time will tell.

Adding software to a 335i doesn't make it a 335is. Just the same that the jb3 on a 335i doesn't make it an M3. Just as taking a Civic and adding a huge turbo doesn't make it a Porsche. It just makes it "as fast" or "faster".

Originally Posted by michaelalex17

"I think the difference would be after market would make 40hp and 20tq more than the 335is."

so your saying a jb3 has 40 more horsepower then 370 horsepower? it doesnt. on map 5 it makes like 330 horsepower or something like that, and it beats a car with 370 horsepower.

[MD 335is]

Thanks for the great info -

The key for me is the overboost is factory stock for the 335is, I don't like to mod my cars - I like everything with the factory warranty.

[Kayani_1]

Kevin, adding a software and few simple upgrades like larger oil cooler, BMW performance suspension etc....on a manual 6-spd N54 335i does turn it in to pretty much 335is or a hyper 335is with even more power and better handling.

On the other hand the optional DCT is one thing that is special and specific to 335is that can not be bought on a N54 335i auto.

As far as the JB3/JB4 335i vs 335is comparison goes it is not like Porsche vs turbo Civic. It might be more like turbo Civic vs Civic Si.

Now comparing M3 vs JB4 335i is entirely different ball game unlike 335i vs 335is. The M3 is a superior car no doubt. However, it is not without flaws. The M3 does not offer no where near the torque of JB4 nor the gas mileage. The JB4 might make a 335i equally fast or faster then M3 with few mods. The JB4 is hands down also better daily driver then M3. However, overall M3 has far superior driving dynamics due to greater handling/braking etc.

But the difference is still not Porsche vs turbo Civic. But rather Porsche Cayman S vs Porsche Cayman R.

Originally Posted by KevinJ

Adding software to a 335i doesn't make it a 335is. Just the same that the jb3 on a 335i doesn't make it an M3. Just as taking a Civic and adding a huge turbo doesn't make it a Porsche. It just makes it "as fast" or "faster".

[Bavarian Black]

Originally Posted by Kayani_1

Kevin, adding a software and few simple upgrades like larger oil cooler, BMW performance suspension etc....on a manual 6-spd N54 335i does turn it in to pretty much 335is or a hyper 335is with even more power and better handling.

On the other hand the optional DCT is one thing that is special and specific to 335is that can not be bought on a N54 335i auto.

As far as the JB3/JB4 335i vs 335is comparison goes it is not like Porsche vs turbo Civic. It might be more like turbo Civic vs Civic Si.

Now comparing M3 vs JB4 335i is entirely different ball game unlike 335i vs 335is. The M3 is a superior car no doubt. However, it is not without flaws. The M3 does not offer no where near the torque of JB4 nor the gas mileage. The JB4 might make a 335i equally fast or faster then M3 with few mods. The JB4 is hands down also better daily driver then M3. However, overall M3 has far superior driving dynamics due to greater handling/braking etc.

But the difference is still not Porsche vs turbo Civic. But rather Porsche Cayman S vs Porsche Cayman R.

Completly agree. I've been researching the the 335is for some time now...and im starting to see trends towards it being a lower version of the new M3 v6 T2 and M4. When tuning comes into place, I think all of us that have a N54 PRE 2010 or post 2010 like the 335is will just have to rely
On tuning.is 7 secs of fun as good as unlimited fun. Each to there own. Also the JB4 is so cheap for the 335is. I wonder why?

BB

[dannieloco]

Originally Posted by KevinJ

The 335i has a turbo overboost of 8.7 PSI. The 335is ups this to 14.5 for (7-10 seconds). Recall that the 335i has a nominal boost of 5.5psi with a max of 8.7psi. The 335is has a nominal of 11.6 with a max of 14.5.

The overboost happens under certain load conditions or such as sudden or hard acceleration. Further reports that emphasize this: "temporary peak torque of 370 lb-ft is available under special high-load circumstances, such as when overtaking at higher speeds." Under load the boost is upped from 11.6 to 14.5 in higher gears for up to 7-10 seconds.

Further according to BMWUSA.com "electronically-controlled overboost function to briefly increase torque under full load by another 37 lb-ft.". According to BMW the temporary 37ft lb torque is delivered through the "standard turbo boost function".


"The 335is comes packing 320hp at 5,900 rpm and 332lb-ft of torque is available from 1,500-5,000 rpm. The engineers have tweaked the twin-turbo 3-liter motor to have an overboost function that increases torque to 370lb-ft. The overboost function comes into play at higher engine speeds and gears, similar to that of the Z4 sDrive35is."

The early reports of the 335is said 7 second overboost reported by BMW. There are a few other reports of 10 seconds of overboost. 335is-dyno-test-N54-group-horsepower.jpg[/IMG]

When I step on the gas of my 335is, the car takes off, at some point, i feel boost kicking a few split seconds after gassing it. THe car does a hard gear shift as well - meaning my car shakes a little when this gear change happens. Not sure if this is normal or if my transmission is starting to fail. :/

Has anyone noticed a hard-shift when stepping on the gas?