360whp @ 10psi

[ramialam95]

A couple of months ago i bought a 135i 2009 that had several mods on including a catless downpipe, afe cai, and a costume tune. The owner said the turbos are maxed at 10 psi with 370 whp. The car feels like it has 370whp and iv been in a race with a 335i jb4 @ 16 psi and took him out. What im confused about is why do jb4 and cobbs run a pressure of 16 psi and above to reach 350 - 370 whp while its possible to do it at a lower (safer) boost? The car has a turbo gauge so i can tell the previous owner isnt lying and he showed me a graph of the dyno but is it possible?

[ShocknAwe]

Probably has inlets and outlets on it as well. Higher air volume, lower psi.

[ramialam95]

It has stock inlets and outlets.
Here is a graph on a dynojet before the owner got downpipes on her. It was running at max boost of 13 psi. I dont have a graph after he put downpipes but he told me they changed the max boost to 10 psi and it was producing ~360whp. The only mod was afe cai.

[bNks334]

Probably because the tuner actually put the car on a dyno and created a timing curve that produces the best power for the given fuel/load.

The JB4 ups the load with more boost, and adds more fuel, but it doesn't tune timing to maximize power gains. The DME is left to continue to use the stock timing tables. People then need to dump E85 into the tank to prevent the resulting knock. The solution is BMS's "BEF" or a custom flash tune, which as you can see is a superior method of tuning.

[heist_tub]

Sounds like a safe tune. I'm 17-18psi but probably will blow my turbos after a while lol. I'm on e85 tho

[loesch]

There's no way to know what's going on unless you put it back on the dyno with someone that can read the flash. My guess is they are tuning in tons of timing for 93 and that's why they said the turbos are "maxed". The turbo's aren't actually maxed until 19psi+ but you won't get there unless you pull some timing and add octane. Then you'll be closer to 450hp.

[ramialam95]

I asked the tuner and he said increasing boost isnt the only thing it increased power. There is also timing which helped in the increase like you guys said. I wonder why many people use jb4s and cobbs were in a fact a custume tune is better and safer for the tubos

[loesch]

Originally Posted by ramialam95

I asked the tuner and he said increasing boost isnt the only thing it increased power. There is also timing which helped in the increase like you guys said. I wonder why many people use jb4s and cobbs were in a fact a custume tune is better and safer for the tubos

More boost and less timing is safer for the engine. Turbos are expendable.

[ramialam95]

Originally Posted by loesch

More boost and less timing is safer for the engine. Turbos are expendable.

Yes but the n54 cylinders and pistons can withstand a lot more than the turbos having more boost. I havent heard of an n54 breaking but iv heard enough about turbos goin bad.

[titium]

Originally Posted by ramialam95

Yes but the n54 cylinders and pistons can withstand a lot more than the turbos having more boost. I havent heard of an n54 breaking but iv heard enough about turbos goin bad.

you're delusional if you think the n54 is unbreakable. plenty of blown motors.

obviously turbo failure rates are going to be higher considering the heat they produce and speed they spin at. the slightest imbalance is amplified massively at 120k rpm.

the other thing to consider with the tunes is boost taper up top. while you might have 15psi in the mid range you might only have 10psi up top.

by not tuning ignition timing, fuelling and vanos and simply upping boost you're leaving alot of safe reliable power on the table.

[ShocknAwe]

pistons aren't as strong as you think. rods are pretty weak and the piston heads like to crack.

[ramialam95]

Originally Posted by ShocknAwe

pistons aren't as strong as you think. rods are pretty weak and the piston heads like to crack.

Well thats a shame. I always thought the n54 internals are strong for oem specs . What gave me this idea are those single turbo n54s with +550whp on stock internals.

[ShocknAwe]

Originally Posted by ramialam95

Well thats a shame. I always thought the n54 internals are strong for oem specs . What gave me this idea are those single turbo n54s with +550whp on stock internals.

They are strong. But power for power its a better idea to run low timing high boost and full knock protection rather than the other way around. Just illustrating what can go wrong.

Doesn't mean the OP is going to pop something at his power level, but if that's the way his tune was done, it's not considered the safest way to do it on this platform.