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2002 Cadillac Seville STS
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192 Posts
Discussion Starter #1
Ok,

I have looked over the entire site and although I have found many people stating they have put a 80mm throttle body on their 00+ Sevilles, MINE IS AN 02', I cannot find any information on how much work is required to accomplish this task. I have been told by the fabricator of the wider TB that my particular year Seville does NOT require a TB spacer behind the unit, BUT, according to my service manual, it looks like the TB bolts onto a water cooling assembly, which is right behind the TB. Does that piece need to be bored as well? Can it even be bored?

So, basically, I am look to see how long it took the members on this forum to switch out their TB and any advice of problems that occurred on an 02 Seville.

Thanks in advance....

Mike
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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69,105 Posts
I have been into the throttle body area of my '02 STS. The spacer/coolant passage is not 80mm. I would hazard a guess that trying to go to a larger throttlebody may well open a can of worms you might not want to deal with. Given the cubic inch displacement of the engine, max RPM, intake manifold configuration, head port configuration, and air intake ducting, what do you expect to gain, at all engine speeds, over the "stock" installation??? (Don't forget that the 4-valve arrangement is done to squeeze the best flow/HP out of a small engine.)............just a few thoughts and a "heads-up".......
 

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2015 Mazda3 S GT Hatchback 2013 Kia Optima SXL
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2,817 Posts
I cannot speak from experience with the Northstar. But, I can with a Ford 4.6 Triton. I installed a larger throttle body on my '97 F-150. ALL of the horsepower gains were over 3,500 RPM. But, it had a drastic dropoff in low end torque. And lets face it, unless your last name is Force or Bernstein, losing low end torque will make you very unhappy. Your N* rarely is in that range. Why spend the $ for the few seconds that you will use it, considering the major drawbacks? Just something to consider.

Don
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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:thumbsup: In my header ^^ there's an '04 F150 4.6 Triton. Exactly the same experience. Went back to stock.
 

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2015 Mazda3 S GT Hatchback 2013 Kia Optima SXL
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:thumbsup: In my header ^^ there's an '04 F150 4.6 Triton. Exactly the same experience. Went back to stock.
As did I. After that experience I have left the intakes of my vehicles alone. Allowing more air into a stock engine is torque suicide. Only after increasing the engines ability to gulp more air (larger valves and the like) should anyone increase the throttle body size. Some engines have a definitle restriction at the TB. But most do not. I hope this may help someone to not mess with it. It is just like throwing $ away.

Don
 

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2002 Cadillac Seville STS
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192 Posts
Discussion Starter #6
Well, I have read many articles that RSM racing was making an 80 mm TB for the North Star and several people had put this on their car with no problems. If you have put the Corsa Exhaust system on the car, Which was designed BY CADILLAC ENGINEERS and produced by Corsa for the (THIS was an option FROM cadillac and was offered to be put on the STS AT THE DEALERSHIP) , it would seem to be that their would be a ligitimate gain from the exhaust system. ON top of that JetChip makes a MAF sensor that is designed for the car, which has had positive results, from what i have read.

There has got to be someone that has done these mods and seen an improvement or loss after the 80mm upgrade. I guess I can dyno the car, put the Secondary 80 mm TB on the car and then check the power band. I was just trying to see if anyone else had approached this from a scientific/logical perpective.

Mike
 
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