Boost Pressure

[kosmo96]

I have a 2004 bone stock non-x50 TT. What is the factory spec bar under full acceleration load? I'm getting 1.2 bar. Thanks

[pierre]

1.2 bar? Seems quite high for a stock 996 TT. I think the max I had before I upgraded mine was 0.9. Now, with the Sportec stage 3 upgrade, I'm getting 1.2.

Is your car really stock?

[jpflip]

According to what I have learn so far about the TT. You definitively have a modified ECU. Non modified one can get max .7 bar.

Edited August 5, 2008 by jpflip

[jpflip]

see this link, previous discussion

boost

Edited August 5, 2008 by jpflip

[pierre]

0.9 bar with a stock 996TT:

[wross996TT]

A non-X50 (or S) will get between .6-.7 stock....we are not talking spikes. This is what you maintain at WOT in 3rd or 4th +. Anything over that is not stock.

[Chuck Jones]

If you are sure your car is a stock TT, then you're leaking probably thru your diverter valves. overboost like that usually means a vacuum leak. Did you recently upgrade your DV's? .9 is what you get with a stock X50

[jpflip]

0.9 bar with a stock 996TT:

Hello Pierre. I got my info from this thread and I have to admit I never saw anything higher than .7...stock boost

[kosmo96]

Thanks everyone for your timely, informative and thorough responses. It may have been a spike since I was WOT in second and I haven't seen numbers higher than .8 before. I hadn't thought of a leak and I'll do more testing in the next day or so and let you know how I make out. By the way, I bought the car with only slight usage and it served as a garage queen and tourer. The previous owner was not likely to have made modifcations, but the world is full of surprises. I still have some factory warranty left and cpoe so I should be ok if my test runs show high boost numbers.

[wross996TT]

if it is a leak....it would reduce your boost, not increase it (boost is lost on a leak). Plus you would likely throw codes and feel a performance hit. You could spike .8 on a stock non-x50 with the right environmental conditions.

[GT2IAN]

Pierre,I was impressed with .9 on a stock TT but more impressed with the speedo reading! :o I suppose you were just going to the shops to get some milk? :lol:

[pierre]

[...] I suppose you were just going to the shops to get some milk? :lol:

Yeah, you know how it is with these fast cars... You don't pay attention for a few seconds and suddenly you're slightly above the speed limit. :D

Sorry to slide off-topic, but you might like this one too:

(no, the car wasn't stock anymore...)

[Chuck Jones]

if it is a leak....it would reduce your boost, not increase it (boost is lost on a leak). Plus you would likely throw codes and feel a performance hit. You could spike .8 on a stock non-x50 with the right environmental conditions.

WROSS: When I installed my diverter valves, I didn't seat one of the DV's properly and reused the ford hose clamp and it leaked causing an OVERboost reading on my boost gauge. When I switched out the ford clamps for stainless screw clamps, the overboost went away.

Edited August 6, 2008 by Chuck Jones

[wross996TT]

Sorry, Chuck (definately not flaming here)...could you help me understand this...perhaps provide a scientific hypothesis as to why your boost would go up? If your DV goes bad you can't hold boost, lag increases....If your dvs fail...I don't consider that a vacuum leak BTW...if they can't detect the vacuum build up in the intake manifold to remove pressure from the other side of the throttle plate....then serious turbo damage.

[Chuck Jones]

Scientific hypothesis? Hell I can't even spell hippopatomus much less give you one. All I know is that I installed one of the DV's improperly and the ford clamp wasn't sealing off the bottom of the DV....not the part that went into the F hose, but the one that goes into the downpipe....and I eventually took it into the dealship who told me that the DV was leaking which was why it was overboosting.

That's about the extent of my MIT degree in automotive engineering....guess you'd call it hearsay from the dealership.

And Bill....I think I know you well enough to know that if you did flame me, it would be in the spirit of a friendly gig.

[jpflip]

[...] I suppose you were just going to the shops to get some milk? :lol:

Yeah, you know how it is with these fast cars... You don't pay attention for a few seconds and suddenly you're slightly above the speed limit. :D

Sorry to slide off-topic, but you might like this one too:

(no, the car wasn't stock anymore...)

Wow! I am amazed. Pleasure of living in an European country...

[MY996TT]

Scientific hypothesis? Hell I can't even spell hippopatomus

This is funny!

I do agree with wross996TT; it should drop boost when leaking. Maybe when the DVs weren't properly installed, they actually block the flow.

[jpflip]

May be the ECU is inform by the pressure sensor of a pressure drop and ask the turbos to produce more boost... But there is a leak and there should not be an increase of pressure...Uhm... Busted or plausable ?

[waymegelli]

Let me butt in here and ask a question based on my recent experience. I have a 2002 996TT and recently did some upgrades. Before the upgrades, I typically saw 0.7 or 0.8 boost under sustained acceleration. I did a Softronic ECU flash and saw 1.2, although this was only on one or two occasions. Then I installed Forge diverter valves with the medium pressure spring and only see 1.0 max now. Do I need a weaker or stronger spring, or do you think I have a leak?

[wross996TT]

Let me butt in here and ask a question based on my recent experience. I have a 2002 996TT and recently did some upgrades. Before the upgrades, I typically saw 0.7 or 0.8 boost under sustained acceleration. I did a Softronic ECU flash and saw 1.2, although this was only on one or two occasions. Then I installed Forge diverter valves with the medium pressure spring and only see 1.0 max now. Do I need a weaker or stronger spring, or do you think I have a leak?

What are all of your mods? and what turbos do you have? (if you have K16s, then 1.0 is probably right for pump gas)

First....what is your sustained flash? Spikes don't really count...so is it possible your sustained boost was 1.0 before? (to check sustained boost do WOT in 3rd and 4th).

Second, get your codes read as this may provide some clues.

Third, did you install the Forge DVs properly? Check the connections.

Fourth, you do need the Forge DVs set-up properly with your other mods. I believe there are 2 springs (green and yellow) and some shims (washers)....check with your tuner for their advice for your car.

Edited August 9, 2008 by wross996TT

[waymegelli]

The engine related mods are a Europipe Stage 1 exhaust, the softronic flash and the DVs. Turbos are original K16s.

First - My sustained flash??? I assume you mean boost - I haven't driven it too much lately, but I'm fairly sure it's 1.0. I'll try to find a good place to verify that soon.

Second - If I take ti somewhere to get the codes read, what do I tell them to look for?

Third - I believe I installed the DVs correctly, but I've been told I should double check the bottom of the forward one. Also, I should replace the ford clamps with stainless screw clamps. There goes my weekend.

Fourth - You're correct about the different springs and shims that come with the DVs, but my tuner doesn't respond to emails anymore, so I'm just guessing and hoping RennTech people can help.

What are all of your mods? and what turbos do you have? (if you have K16s, then 1.0 is probably right for pump gas)

First....what is your sustained flash? Spikes don't really count...so is it possible your sustained boost was 1.0 before? (to check sustained boost do WOT in 3rd and 4th).

Second, get your codes read as this may provide some clues.

Third, did you install the Forge DVs properly? Check the connections.

Fourth, you do need the Forge DVs set-up properly with your other mods. I believe there are 2 springs (green and yellow) and some shims (washers)....check with your tuner for their advice for your car.

Edited August 13, 2008 by waymegelli

[wross996TT]

The engine related mods are a Europipe Stage 1 exhaust, the softronic flash and the DVs. Turbos are original K16s.

First - My sustained flash??? I assume you mean boost - I haven't driven it too much lately, but I'm fairly sure it's 1.0. I'll try to find a good place to verify that soon.

Oops...yes boost. 1.0 is fine for K16s...they really are not very efficient at boosts higher than that. Remember is not just about boost, but power.

Second - If I take ti somewhere to get the codes read, what do I tell them to look for?

Read all of the codes (use a durametric, PST2 or PIWIS)

Fourth - You're correct about the different springs and shims that come with the DVs, but my tuner doesn't respond to emails anymore, so I'm just guessing and hoping RennTech people can help.

Green with no shims...1.0 bar.

[octurbos]

Your 1.2 bar was spikes and not sustained boost. Since you have K16’s keep the boost at 1.0 bar. 3rd gear WOT then look at the boost gauge. You can also set up a video camera pointing at the speedo and boost gauge. Then run it through the gears a few times and then post the video and let us examine the outcome.

[waymegelli]

Your 1.2 bar was spikes and not sustained boost. Since you have K16’s keep the boost at 1.0 bar. 3rd gear WOT then look at the boost gauge. You can also set up a video camera pointing at the speedo and boost gauge. Then run it through the gears a few times and then post the video and let us examine the outcome.

Cosmo96 - Sorry to have hijacked your thread. I hope you got some benefit out of this, too. I'll do as suggested above and start a new thread after I figure out how to post a video.

[octurbos]

Post a video like I did below:

The silver SG700 was much faster today on race gas.

http://www.911turboregistry.com/sg700_996tts.wsf

The 993 GT2 with 800HP (at least) against my fat cab (996TT S Cab).

http://www.911turboregistry.com/993tt996tts.swf

Proto997TT, 993 GT2 and 996TT S. Watch the fire come out of the tail pipes of the 993TT.

http://www.911turboregistry.com/proto997TT993TT996TTS.swf

On our way to the location

http://www.911turboregistry.com/onourway.swf

Here is a run with the Black 996 TT Evo 700 and the 996TT S Cab. You can not even hear my engine over the Evo’s exhaust note.

http://www.911turboregistry.com/evo700black996tts.swf

Here is a few runs with the Black Evo 700, Supercharged M3 and the 996TT S Cab. This is a up hill run from 2nd gear at 30 MPH.

http://www.911turboregistry.com/m3superevo700black996tts.swf

Another up hill run with the Black Evo 700, Supercharged M3 and the 996TT S Cab from 2nd gear at 30 MPH.

http://www.911turboregistry.com/m3superevo...ack996tts_2.swf

One run with the Proto 997TT and my 996TT S Cab. At 1.2 bar, he still takes me but maybe I slowed it down a bit. You be the judge.

http://www.911turboregistry.com/proto997tt996tts.swf