Sounds like you're having fun Scott. I'm looking forward to hearing about your new runs.

A simplistic way to expalin this is that more timing will give you a more responsive (peppier) engine off of boost ala n/a but it limits the level of boost you can run safely. This is all relative to the turbos your run and the cfm they produce at a given psi.

 

I wonder how you guys would do with the larger turbos, scott when do you hit full boost on 1.6 bar?

any of you porsche guys tried the precision turbos or holset or borg warner

I wonder how you guys would respond to lower boost numbers with a larger turbocharger, would it kill the low end completely....i doubt it as your twin 35r buddy is having great midrange

I am assuming a precision 6262(tiny bit smaller iirc than a 35r) or 6765(larger than a 35r but smaller than a 40r) will kill it has anyone tried a 40r? or hta 35r?

 

There are several running the 35's in various trims hopefully they can chime in on the driveability.

 

funny stuff giving the tuners an ulcer. But great information for sure. thanks for posting it.

 

Thanks much ReeknHavic that's is better to understand.Now i know.

 

tuners tune the torque curve, so what kind of turbo you have has tons of impact on that; a large big horsepower turbo will usually not be able to achieve big torque; this also brings up your engines volumetric efficiency as the car with better flowing heads and better setup lb for lb of boost with the same turbo will make a nicer curve and there is another variable, as scott said his buddies car with great flowing heads is doing great with probably 5-10lbs per min more of a turbo at a lot less boost, those heads are no joke, his V. E. is wayyy up with that car, probably revs wicked fast too

some tuners tune with more boost and less timing..and some idiots just do both but they might not be idiots, just have the car on kill mode :devil:

 

Great thread, great info.
I just woke up from a deep slumber, I thought 996 TT motors were maxed out
at 1.44 bar as that is the max that I ever ran. :-)
Cheers to all my Pcar buddies ! and yes I am 100% satisfied driving a Volvo...

 

porsche there is not substitute:d

 

Marty you coming in October? I am hopefully bringing my Polaris RZR. It is not as roomy as our ghetto Limo from the last years, but it will sure roll them up if we get in a race on the side line LOL!

 

Justin - U should host a live thread chat on this topic sometime. I am pretty unedumacated when it comes to this topic. I am on my very first car with FI and I am still trying to learn.

Good stuff.
Eric

You weren't in slumber mode when you blew by on 5 Saturday.

I was just cruising down the road in the GT2 Saturday and next thing I know I'm getting the ricer flyby.


That little limo is going up for sale if anyone has interest. I'll even include a copy of boom boom pow or whatever the heck he was playing in it.

 

I will be bringing multiple boxes of wine to the mile. I like to keep it classy in those parts! Be prepared!

 

I couldn't help but think of the Ron Burgandy Anchoman show "Keep it classy San Diego."

 

LOL I was thinking of that when I wrote it LOL! Wasn't sure if anyone was going to catch it though.

 

OH, MY HEAD. Ok, if I win do I get a GT2RS? I'll say 18 psi at 30 degrees advance. KABOOM. !!!

Ok, so now my question is lets say you have 18 psi at 20 degrees and that equals in power 30 psi at 10 degrees, which is the better all around setup? the higher pressure or the more advanced timing? How do the curves differ at this point.

 

Good one!!

It really depends on the design of the engine at that point, but let's take the 996 TT engine for example(seems relevant in this case ). Because of the cam profile, head design and intake manifold; you have various points in the curve that require varying amounts of advance... Theoretically(let's use your 20 degrees advance example) if you were running 20 degrees of advance at 5000 rpm at 18psi on a GT35R setup with moderate hotsides(we'll call this peak torque ). On the TT, you might actually end up with as much as 30 degrees by 7500rpm at 18psi. Maybe even more; without roasting any metals. So my example was technically a trick question as noone actually asked WHERE in the powerband these advance numbers were. Porsche actually designed their mapping around this and advanced timing like crazy after 6500rpm or so. This was done to combat the turbos, head design, cam profile, intake manifold designs while still making power. They coupled all of that with a sensitive knock sensing system though. After changing all of those things.... your mapping also has to change to reflect this. Bear in mind that this is all "surface tuning" at this point. We'll assume that the bore and stroke were already taken into account along with the squish(head design) and about 20 other vairiables. Since Porsche uses some form of calculated load, we'll use that as gospel for the determination of what the actual ignition advance is, as opposed to actual load(boost), or just MAF values. So using calculated load, it takes into account injector pulsewidth, MAF, Boost Pressure, RPM, etc to determine the proper advance at that particular moment in time(pretty sleek stuff for something designed in the late nineties). Tony at EPL might have more insight as to the exact algorithm Porsche uses to determine where everything needs to be. The newer cars get a bit more in depth with time based firing as opposed to solely position based firing.

Scott... So sorry to hijack your thread, but you always get stuff stirred up with giving everyone tons of info on your build

Justin