[Noize]

Originally Posted by Former_Boosted_IS

First, if my info was bad, please let me apologize.

I am confused then if the turbo has no problem producing 14 psi at x rpm (say 1800), then how is that boost falling off at high rpms? The turbo is fully spooled and should never fall off in boost right? If it is beyond its effeciency range isn't that something completely different then saying the boost is falling off?

No, because these are pretty small turbos, and were designed to be run in a 335i at a lot less than 14psi. As you continue to rev, they're a bit beyond their efficiency as this big 3.0 liter fills its lungs up completely, and the boost will taper since they're being pushed pretty hard. But the other thing is that since they are so small and efficent at spooling and low end torque, their top end power characteristics leave a little to be desired.

Think of something simple like a small T25 on an inline four like a SR20DET or a 4G63. You can make decent torque and boost in the midrange, but the boost will taper gradually toward redline. Its not the engine's fault. Put a nice medium frame Garrett 3076 on there and provided the engine can withstand it (race gas, etc), that turbo will hold 28psi to 7800rpm with ease.

I'm sorry if I sounded harsh before.

[Noize]

Back on topic, how bout that 400whp?

And Shiv, spill the beans about the other thing you're controlling, please?!? My guesses:

1) VANOS
2) Throttle plate

[Garrett]

Originally Posted by Noize

I'm sorry, but you need to stop spreading misinformation and learn what the heck you're talking about.

First of all, nobody who tunes cars "backs off timing" at high RPM. If you're talking about offsets, you need to look at the actual values the car is seeing in the ECU. The risk of detonation as you put it is not highest at high rpm at all. Its variable depending on mapping and has nothing to do with high revs. At boost onset in low RPM, the values are low, but they increase substantially as the revs climb toward redline. Wanna knock? Run even half the timing at boost onset that you're running at 6500rpm. With interception, a tuner might reduce timing in offset values to offset the natural advance of timing since he is really tricking the engine's air flow sensors to think its running different than it really is. But those values are selected because he is trying to make the engine happiest in all rev ranges.

As far as enrichening at high RPM under load, yes that's a good thing as extra fuel is used for in cylinder cooling.

The main place where you're off base is with these tiny stock turbos. With race gas (more timing allowed) you can increase power earlier, but these tiny turbos will peak sooner. Every engine has a VE, and you can't overcome the size of the stock turbos. Put cams in this engine and you'll see it peak and fall sooner as well.

Your point that the stock snails can hold 14psi at redline is moot. Who cares what boost they can hold? The inportant question is: Are they efficient up there? Obviously not. Look at the stock curve and look at the modified curves. If you've tuned several turbo cars, you can take one look at those turbos and realize that each is being fed by 1.5 liter and know they are not designed to make big power at high rpm. BMW says the car in stock configuration can achieve peak torque starting as low as 1300rpm for crying out loud! What more evidence than that do you need? They are small to make the car seem NA and enhance drivability, not to rev and make power.

The IS300 thing is off topic, but still just full of wrong. You're comparing an iteration of 2JZ that was designed to be NA to the Supra engine. Get a grip, of course its not as internally robust! The compression ratio point is moot too, because our engine is direct injection versus the IS300 motor which was not.

No wonder people get confused or afraid reading car forums. There's more misinformation from bad posts like yours than help from knowledgable ones!

Great post. Some people just don't understand macro knowledge!

[Former_Boosted_IS]

Originally Posted by Noize

No, because these are pretty small turbos, and were designed to be run in a 335i at a lot less than 14psi. As you continue to rev, they're a bit beyond their efficiency as this big 3.0 liter fills its lungs up completely, and the boost will taper since they're being pushed pretty hard. But the other thing is that since they are so small and efficent at spooling and low end torque, their top end power characteristics leave a little to be desired.

Think of something simple like a small T25 on an inline four like a SR20DET or a 4G63. You can make decent torque and boost in the midrange, but the boost will taper gradually toward redline. Its not the engine's fault. Put a nice medium frame Garrett 3076 on there and provided the engine can withstand it (race gas, etc), that turbo will hold 28psi to 7800rpm with ease.

I'm sorry if I sounded harsh before.

Hey not a problem at all. I am looking for nothing more than solid info on the car and find it concerning how often the "my feeling" stuff is used here.

So as more air is forced through this smaller turbo, how does the boost fall off? Is it that the air flow becomes turbulent because it is beyond its efficiency?

Edit: Kind of funny how people jump on the bandwagon and start to bash? I am just trying to weed my way through garbage and real knowledge, but I have a great deal of difficulty figuring out who really knows what they are talking about on here sometimes.

[S4to335]

So...what happens when you run 2.0.2 with 91 craptane gas here in California? How much do you lose? We all know about 100 octane gas stations here in the bay area...and can fill the car on occasion with 100 octane..but if you just driving around..can the car with 2.0.2 still run decently with 91 octane? Any dyno's on that?

[wiltshp]

Shiv, or anyone else, why are the torque and hp curves so bumpy. Shouldn't this be a smooth slowly increasing line? Is hp dropping off? If so, I hear people talking about how smooth the car is, but with those bumps, you'd think it would be jerky?

[Garrett]

Originally Posted by wiltshp

Shiv, or anyone else, why are the torque and hp curves so bumpy. Shouldn't this be a smooth slowly increasing line? Is hp dropping off? If so, I hear people talking about how smooth the car is, but with those bumps, you'd think it would be jerky?

Because your starting to reach the limit of the components and their function btween each.

[HyperM3]

Congrats on 400hp. Too bad you guys arent making any records for shipping product on time though.

[scottp999]

Originally Posted by HyperM3

Congrats on 400hp. Too bad you guys arent making any records for shipping product on time though.

+1

[S4to335]

Originally Posted by HyperM3

Congrats on 400hp. Too bad you guys arent making any records for shipping product on time though.

LOL

[wiltshp]

Originally Posted by Garrett

Because your starting to reach the limit of the components and their function btween each.

What exactly do you mean. What components? What functions?

[Driver72]

Great job Shiv and Vishnu team.

Can we see a 91 Octane v2.02 tune dyno?

Thanks guys.

[purplewidow]

480bhp hot damn i think you would definitely be in high 3's 0-60 and maybe 11.9 qrt...maybe less...this is crazy impressive shiv!!!!too bad no one has an lsd out for us now with all the welded diffs!!!! guess we'll just have to wait!!!!!

[jpsimon]

sooooooooo hows about them videos


//edit// i guess it's only 8am on the left coast...

[M3KILL3R]

Congrats guys!Awsome numbers!

[bimmermans54]

It just doesnt make sense to me. Is there a way to see what the boost numbers are? I mean, AA pushed theirs and the turbos broke, so there is only so much that you can do with the turbos. Can we see what it does on 91, and 93 octane? Boost levels, and exactly how are you pushing the power?

[S4to335]

Originally Posted by purplewidow

480bhp hot damn i think you would definitely be in high 3's 0-60 and maybe 11.9 qrt...maybe less...this is crazy impressive shiv!!!!too bad no one has an lsd out for us now with all the welded diffs!!!! guess we'll just have to wait!!!!!

Without a LSD..and two wheels powering..the high 3's will not be possible at all.

[jpsimon]

It will be interesting to see how the XI AWD system holds up with all this power.

[CanadianTSi]

Originally Posted by Former_Boosted_IS

First, if my info was bad, please let me apologize.

I am confused then if the turbo has no problem producing 14 psi at x rpm (say 1800), then how is that boost falling off at high rpms? The turbo is fully spooled and should never fall off in boost right? If it is beyond its effeciency range isn't that something completely different then saying the boost is falling off?

Boost falls off simply because the motor is outflowing the turbo.

[sdiver68]

Where are the 115mph+ traps we would expect?

[808AWD325xi]

Originally Posted by jpsimon

It will be interesting to see how the XI AWD system holds up with all this power.

+100000

[jpsimon]

unfortunately I can't wait... I'm just going to have to do it.

Originally Posted by 808AWD325xi

+100000