Big Bird's transplant. Take 2

[Jean]

Originally Posted by JBL930

Do you know what the set up is? Is it MAF based and Motronic controlled where you get variable boost depending on ambient air temp etc, or is it a fixed boost set up? I know from older topics that Tod at Protomotive prefers to use an EBC, basically ignoring the MAF and mapping the ECU for fixed boost. Which will work fine in an area where you have pretty static weather conditions, in the UK where you can get -8 to +30 the car wouldn't work

730bhp at 1bar is a staggering amount of power, those turbos must be mahoosive..... I would think the lag involved to have turbos capable of that power at that boost level would defeat the object somewhat

It does look very impressive, looking forward to seeing some data, 60-130mph etc, should be right up there with the quickest

Jon, It is a fixed boost setup and I think it is MAF based if I recall correctly. A picture of the original built setup will show it.

The temperature variance limitations is news to me however Assuming you are using a respectable tuner and knock sensing is there.

I have ran my car for 5 years from the Nurburgring to racing it in 120F temps. There is no 730bhp at 1 bar from these setups, GT30 or GT976 regardless, these 993TT 3.8, twin plug, MAP engines will give you around 600-620bhp at 1-1.1 bar in real life with these large Garrett turbos and that's it.

[JBL930]

Originally Posted by Jean

Jon, It is a fixed boost setup and I think it is MAF based if I recall correctly. A picture of the original built setup will show it.

The temperature variance limitations is news to me however Assuming you are using a respectable tuner and knock sensing is there.

I have ran my car for 5 years from the Nurburgring to racing it in 120F temps. There is no 730bhp at 1 bar from these setups, GT30 or GT976 regardless, these 993TT 3.8, twin plug, MAP engines will give you around 600-620bhp at 1-1.1 bar in real life with these large Garrett turbos and that's it.

I'm probably just showing my ignorance Jean, but i thought that most of the fixed boost motors were set up for maximum figures.
Lets say for argument sake 1.2bar in 80F ambient is the safe limit for a particular build, big turbos etc and big power. If you are running fixed boost and take this same car out in 40F ambient the engine will be out of it's operating range due to the denser air, and the ECU will be cutting ignition to save the engine from detonating right? So the map is only good for 80F or you need to turn the boost down for lower temps. Is that how fixed boost set ups work?

I know (i "THINK" i know) that with stock Porsche motronic programming the ECU is set up to stick within fixed airmass targets, therefore in 20F ambient you may only see 0.6bar and then in 120F you may see 1.0bar (figures are made up as i have no idea about the difference in air density with regards to temperature, but you get my point). So the engine will always make somewhere around the same power, and stick within it's safe limits, this way keeping full motronic control of boost.

I'd love to be educated on the pro's and con's of each, really interested in this side of it all

[kojo911]

Rob at scar-go did my twin turbo not to long ago. I may be speaking out of turn but, I've seen that car and I'm assuming it's motronic based w/ a maf, using a 97+ n/a ecu (twin plug). Boost is controled by a Greedy ebc. Hope that helps.

[atan888]

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