LT's vs. Boost Loss
Melting Slicks
Joined: Dec 2008
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Safety Car
Joined: Oct 2001
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From: Dallas/Valley Ranch TEXAS!!!
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Racer
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From: Tahlequah Oklahoma
Burning Brakes
Joined: Dec 2006
Posts: 1,098
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From: Gilroy CA
I have a all stock motor 2007 Z51 A6 car with a A@A SC kit (V2 SI Trim)
making 8.5-9 lbs with a 4.0 sc pulley and meth. I am wanting to put long tube headers with high flow cats and leave the factory mufflers for now, how much boost will I loose, will a 3.8 pulley get me back to the same boost lbs? Will a 3.6 be way too much for a stock bottom end? I am wanting a "safe" 560-590 whp
Thanks in advance.
making 8.5-9 lbs with a 4.0 sc pulley and meth. I am wanting to put long tube headers with high flow cats and leave the factory mufflers for now, how much boost will I loose, will a 3.8 pulley get me back to the same boost lbs? Will a 3.6 be way too much for a stock bottom end? I am wanting a "safe" 560-590 whp
Thanks in advance.
So, to answer your question, you may not lose any boost by installing the headers but with your meth setup, you should be able to add more timing than what I have and reach your HP goals with a 3.8 pulley. I am thinking of adding the meth kit too but I'm concerned just how much power the A6 can take before it breaks.
Melting Slicks
Joined: Dec 2008
Posts: 2,296
Likes: 3
I have a all stock motor 2007 F55 A6 car with a A@A SC kit (V2 SI Trim) making 10-11 lbs with a 3.8 sc pulley (no meth). The SC is one of A&A's newer kits (just installed a couple of months ago) with the new air inlet dongle. I'm thinking that the new dongle may add a little boost pressure since before the headers on a completely stock motor it made 10 psi at WOT. I was expecting somewhere in the 8 psi range with the "standard" 3.8 pulley (with no headers). Since we have 91 octane gas here, my tuner had to drop the timing to 8-9 degrees at WOT to keep it from detonating. It made 518/478 at the wheels and I was happy with that but concerned with the 10 psi boost on 91 octane gas with no meth. I talked to few people and they recommended adding the LT headers to try and drop the boost 1-2 psi and allow for more timing and more HP. I then added a set of ARH catted LT headers. As suspected that leaned out the motor, so my tuner had to add more fuel when he retuned it but the boost did not drop at all. In fact it picked up 1 psi to 11 at WOT (maybe due to the better air conditions). He was able to only add 1-2 degrees of timing (now around 11 at WOT if I remember correctly). The car only picked up 18 HP with the headers, now at 536/496.
So, to answer your question, you may not lose any boost by installing the headers but with your meth setup, you should be able to add more timing than what I have and reach your HP goals with a 3.8 pulley. I am thinking of adding the meth kit too but I'm concerned just how much power the A6 can take before it breaks.
So, to answer your question, you may not lose any boost by installing the headers but with your meth setup, you should be able to add more timing than what I have and reach your HP goals with a 3.8 pulley. I am thinking of adding the meth kit too but I'm concerned just how much power the A6 can take before it breaks.
