What did you do to your NNBS GMT900 Tahoe/Yukon Today?

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kbuskill

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How is that even possible if adding LT headers - effectively letting the engine breath a ton better right off the cylinder heads - instantly increases HP/TQ across the entire RPM range?

I don't want to start another "backpressure is needed" debate, because it's not a debate, and has been debunked many times.
I guess I missed the LT header part of the discussion. I can tell you with stock manifolds, or shorty headers like I have, getting rid of the cats makes for a noticeable loss of bottom end power. It has less to do with back pressure and more to do with losing heat which slows the exhaust gases down and therefore it doesn't scavenge as well. Reducing the diameter of the Y-pipe doesn't allow the exhaust gases to expand so rapidly, which means the gases can't cool as fast, so it keeps the velocity of the gases higher creating more scavenging. At least that is what my research after the fact shows. All I know is having a smaller diameter Y-pipe made restored the bottom end power. Now the argument could be made, I guess, that I somehow have restricted the flow for optimal top end performance. To that I say, I don't really care as this is a 6k lb brick and I spend more time below 4k rpm then I do winding it out to 6k rpm.

To each their own, I was just relaying real world experience to try and save someone else the aggravation.
 

j91z28d1

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ugh. noticed my right front tire is showing some Feathering on the outside is less than 10k miles. I knew they didn't actually do the alignment I paid for, but since it went straight I got side tracked and forgot about it. blah guess I Gotta handle that and rotate them to the back or something.


annoying, I literally hate shops. even good ones are awful. maybe I'll just get out the string and do it myself
 

j91z28d1

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I guess I missed the LT header part of the discussion. I can tell you with stock manifolds, or shorty headers like I have, getting rid of the cats makes for a noticeable loss of bottom end power. It has less to do with back pressure and more to do with losing heat which slows the exhaust gases down and therefore it doesn't scavenge as well. Reducing the diameter of the Y-pipe doesn't allow the exhaust gases to expand so rapidly, which means the gases can't cool as fast, so it keeps the velocity of the gases higher creating more scavenging. At least that is what my research after the fact shows. All I know is having a smaller diameter Y-pipe made restored the bottom end power. Now the argument could be made, I guess, that I somehow have restricted the flow for optimal top end performance. To that I say, I don't really care as this is a 6k lb brick and I spend more time below 4k rpm then I do winding it out to 6k rpm.

To each their own, I was just relaying real world experience to try and save someone else the aggravation.


alot of times louder feels slower too. especially at part throttle as they drone alone.

atleast to my old or ears haha. I tend to like really quiet daily
 
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89Suburban

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ugh. noticed my right front tire is showing some Feathering on the outside is less than 10k miles. I knew they didn't actually do the alignment I paid for, but since it went straight I got side tracked and forgot about it. blah guess I Gotta handle that and rotate them to the back or something.


annoying, I literally hate shops. even good ones are awful. maybe I'll just get out the string and do it myself
Make some toe plates like I did.
 

Grady_Wilson

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ugh. noticed my right front tire is showing some Feathering on the outside is less than 10k miles. I knew they didn't actually do the alignment I paid for, but since it went straight I got side tracked and forgot about it. blah guess I Gotta handle that and rotate them to the back or something.


annoying, I literally hate shops. even good ones are awful. maybe I'll just get out the string and do it myself
I have to find a good shop out my way, back in So Cal I found one that did great work and I had them do all my alignments.
They were honest and did great work.
So honest that when the step son bought a couple year old used car and he took in for an alignment, after a few hours they called him back to pick it up, when he got there they told him it was in spec so no alignment needed, no charge.
They didn't even charge him for the time it took them to setup the machine and get the initial readings.
 

j91z28d1

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I have to find a good shop out my way, back in So Cal I found one that did great work and I had them do all my alignments.
They were honest and did great work.
So honest that when the step son bought a couple year old used car and he took in for an alignment, after a few hours they called him back to pick it up, when he got there they told him it was in spec so no alignment needed, no charge.
They didn't even charge him for the time it took them to setup the machine and get the initial readings.


man I need to find that shop. sadly what I've found sound moving to tx is everyone seems to have their hand out trying to get something for nothing.
 

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