soulsearcher

BVLDARI

preach it brother

SGC

Confirmed that peak boost in my car is just under 1.5 bar with tune.











http://www.youtube.com/user/roadtest.../0/x8H5rUyV3E4

transferred

The long list of those opposed to Sound8 continues to grow ever longer

SGC

I drive it to the office every day, so unfortunately I run a lot of 93 through it.

How much boost are you running with good fuel? Thanks.

Benz-O-Rama

Ahhhhh, so 1.5 after tune. Marcin posted that is was 0.9bar for a 600 stock, and 1.5 for a 65 stock.

It appears, that either his figures aren't correct or your tune did not alter boost.

SGC

I'm not claiming to be an expert, however, I've been told (twice) that on the dyno stock 65s make between 1.1 and 1.2 bar. Modified about 1.5 bar.

But what do I know.

sound 8

Looks like I am getting plenty of co operation.

All you can do is criticize, sign of a small brain.

sound 8

Listen mate, I do not want to pick holes, but according to an MB manual the
stock boost is 1.5 bar. TMC M5 said that you said it was around 22 psi. It doesn't matter how much you tweek an ecu it's boost that gives you the big extra gain. Either the manual is wrong or your dyno reading is wrong.
It's just logic.

Dsmed

Looks like I'm gonna have to print/scan and post the actual document out of WIS.

I can post stock tune dyno graphs with a boost pickup and they usually read about 12-13.5 psi. Which is just under 1 bar. 1 bar = 14.7 psi in case anyone is wondering.

TMC M5

I agree that the MB literature that I have says 1.5 bar. However, in reality it takes ECU tuning to approach that figure. Does MB measure the boost differently? Or is it a matter of 1.5bar is the max, but the ECU limits it?

Tom

sound 8

Now don't take this as a critcism, you usally know these figures but this time it sounds like your bringing to many variables in. If the sock boost is 1.5 bar who is doing the ecu tuning, or what is doing the ecu tuning? If MB measure the boost differently what do you mean. I am used to just putting a boost guage in the system and measuring peak boost in say 4th on a 5 speed.
If 1.5 is stock then is that peak, usually peak boost drops to a sustainable figure, 21 psi dropping to maybe 19/18 psi. I presume the re map takes out the limit or raises it along with fuelling etc. I still can't see a 100 rwhp extra with only 1 or 2 extra psi. I don't pretend to know a lot about modern turbo cars, all of my knowledge was gained on turbo cars over 20 years ago, however I can't see that the big figures have altered that much.

TMC M5

The smartest thing I did was put him on my ignore list... he isn't worth the effort to set straight... or to argue with..

Tom

sound 8

A good excuse for not knowing. Are you twins, or maybe you got something going.

BVLDARI

how does the ignore feature work? Do his posts dissapear?

Dsmed

1.5 bar is where the stock limit is set to. Which means that ECU will open wastegates to keep it from going past that. Every stock 65 will hit that limit on the lower rpm range and tapers of towards redline. The taper in boost is not an ecu function its the turbos running out of breath. I've managed to get 31 psi out of a 65 down low but it tapers of to about 18-20 on the top. BTW ecu shuts down at 29.4psi and does into limp mode due to map sensor going past operating range. Also you'll genarally see slightly more boost on the street vs. dyno.

sound 8

OK just got an e mail from chief tech at my local MB. I asked him a while ago for a stock boost figure. It says SL65 runs low pressure kompressor at 1.3bar
max. That's from a UK MB manual. So that's around 18 psi, so SGC has got
around 22 that's a gain of 4 psi. Working on a figure of around just over 20 bhp per 1 lb boost would give you 80 + bhp gain which seems about right.
Sorry to be vague but no one is sure down to the last dot. So 4 gets you a lot more!!
Enmjoy your ride.

MarkoCL65

HEY! READ THIS AND SOAK IT UP.

TIMING AND AIR FUEL RATIO HAVE A PROFOUND EFFECT ON POWER OUTPUT. YOU CAN GAIN OVER 100 HP WITH THESE CARS (V12TT AND MOST FORCED INDUCTION CARS) KEEPING THEM AT STOCK BOOST BY RUNNING LOTS OF TIMING.

MarkoCL65

It is actually a question that requires a complex answer. All V12TT cars have difficulty maintaining a pre-set boost level due to the inefficiency of the turbochargers. The compressor wheels are too small and cannot feed a V12 that is revving out. There is a peak boost number that is hit early in the rpm range and there is the boost number with which you end up at the top of your rpm range, or shift point. We have hit over 30 psi at a very low rpm, but could not hold it for more than a 100 rpm. During a quarter mile pass the boost doesn't go above 22 psi. The engine rpm range during the pass is from 3800-5700 rpm and the boost drops from 22psi to 17psi in that range.

The reason I'm against running 93 octane in a V12 car that puts down over 600 RWHP is this. There is only one way (assuming the turbos and engine are stock) to get more horsepower out of this platform once the turbos are maxed out. That is with ignition advance, or advanced timing (AFR plays a role, but I'm assuming nobody in their right mind wants to gain power by running leaner than stock). To put down over 600 RWHP the timing map is aggressive and NOT 93 octane friendly. What happens? Timing and boost are being reduced and throttle body closes (ECU protecting the engine) limiting overall power. The car can actually run slower on 93 octane gas than it does with a stock tune. I also don't like to leave the integrity of my motor in the hands of a sensor or two. They sometimes go bad.

Benz-O-Rama

Focusing on your second paragraph, are you stating that it's not safe to run 93 octane on a tuned V12TT if it's approaching 600WHP? I'm just a hair under 500whp on a historically low reading Dyno Dynamics, so who knows (and who cares, really) what the dynojet number is. But, I only run 93 octane. Do you only run race gas in yours? I know my AFR is still pretty close to stock, although I don't have my chart in front of me. I remember the AFR being close to the fat stock number.

MarkoCL65

It's "safe" because of the ability of the ECU to read knock sensor output and adjust the necessary parameters. To make 600+RWHP there are a few things going on:

1. The turbos are way out of their efficiency range and the compressed air is exremely hot. This creates ideal conditions for detonation, especially with stock intercoolers.

2. The timing map is aggressive which in turn creates more cylinder pressure and heat, further contributing to the ideal conditions for detonation.

3. Stock intercoolers are restrictive. Any restriction causes more heat. Hot charged air and an aggressive timing map are not what you'd consider a recipe for longevity.

A higher octane fuel does lower combustion chamber temperatures. That's my fuel of choice (100 oct unl) Normally a 5.5 or 6.0L engine can make up to 750 RWHP safely on pump gas, but not these cars, not with these restrictive intercoolers, small turbos and manifolds.



I don't think you have anything to worry about.

Benz-O-Rama

So it sounds like next up should be a larger H/E, chiller in the trunk, and a 40 gallon drum of Sunoco 104. Then lean that F*cker out!

SGC

Thanks Marko.

I agree 100%. The ECU will pulls quite a bit of timing on my car with 93 octane.

sound 8

Please read my earlier posts where I say that peak boost is not what your car will hold. Full throttle in a high gear will give you a sudden high, we call it over boost, before it settles down and holds. I can believe that a peak of 30 psi could be seen for a second before it drops to a level where it holds, maybe
18-19 psi. However running a engine with lots of ignition and lean is likely to cause detonation. I think most tuners simply up the boost with the necessary ecu adjustments, it's quick,safe and makes them a load of bucks.