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Power loss with LSD and HFC?

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Old Jul 11, 2007 | 01:51 PM
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Power loss with LSD and HFC?

I used to think my evo was pretty peppy with the mods I had the mods below in my sig minus the LSD and HFC. I had the HFC and LSD installed around the same time and after they were installed it seems the car doesn't have the throw you back in the seat feeling like it used to. It still boosts fine and the RPM's seem like they climb up just at fast but It feels like a lost a significant amount of torque. Has anyone had this issue after they installed an LSD in their 03/04 or after installing a HFC? I had the car tuned by Sean Ivey before the LSD and HFC so I dont think a tune is the issue.
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Old Jul 11, 2007 | 02:05 PM
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You will lose a little power to the ground with the installation of the LSD, this is expected. You will also lose a little from the HFC, so all in all, expect a decrease of about 10-15whp with both items installed. Hey, at least you have more front end traction now!
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Old Jul 11, 2007 | 02:07 PM
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Originally Posted by sonicnofadz
You will lose a little power to the ground with the installation of the LSD, this is expected. You will also lose a little from the HFC, so all in all, expect a decrease of about 10-15whp with both items installed. Hey, at least you have more front end traction now!
Was the HFC replacing a test pipe or a stock cat?

How does an LSD decrease power output to the ground?

Scorke
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Old Jul 11, 2007 | 02:09 PM
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Originally Posted by scorke
Was the HFC replacing a test pipe or a stock cat?

How does an LSD decrease power output to the ground?

Scorke
There is more drag, and heat losses associated with a limited slip differential than that of an open differential. I am assuming he went from a straight pipe to HFC
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Old Jul 11, 2007 | 02:27 PM
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Originally Posted by scorke
Was the HFC replacing a test pipe or a stock cat?

How does an LSD decrease power output to the ground?

Scorke
Yes I did have a testpipe before.
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Old Jul 11, 2007 | 02:29 PM
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well there u go...it is what it is...take that hfc off..
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Old Jul 11, 2007 | 02:34 PM
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Dosen't smell as bad I bet. You might want to get re-tuned for the HFC, should have more back pressure now.
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Old Jul 11, 2007 | 02:37 PM
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you shouldnt need a re-tune going from a tp to a hfc.
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Old Jul 11, 2007 | 04:42 PM
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I had to use a HFC to pass a safety inspection once, I noticed a reduction in:

1.) Acceleration
2.) smell
3.) Noise

Cat's are for wimps!
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Old Jul 11, 2007 | 04:52 PM
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Preach On!
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Old Jul 12, 2007 | 04:31 AM
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Originally Posted by bluebyu36
well there u go...it is what it is...take that hfc off..
I would be more than happy to put on a tp again but after I was behind my friends catless car you could smell it two blocks away and it really bothers anyone behind unfortunate enough to be behind you. Also in NY recently there have been a couple of instances of cops checking for cats. The whole point of the post really was to see if the power loss was caused by the cat alone or by the LSD and HFC.
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Old Jul 12, 2007 | 06:41 AM
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Originally Posted by rcheung
I would be more than happy to put on a tp again but after I was behind my friends catless car you could smell it two blocks away and it really bothers anyone behind unfortunate enough to be behind you. Also in NY recently there have been a couple of instances of cops checking for cats. The whole point of the post really was to see if the power loss was caused by the cat alone or by the LSD and HFC.
Well put the TP back on and see if its faster, if it is all the losses were from the cat. If your just worried about getting caught(don't know how the smell can be your main concern) get an exhaustshop to weld the stock heatshield around it.

Scorke
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Old Jul 12, 2007 | 06:56 AM
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We put a highflow cat on my friends 05 EVO last week, and he mentioned a noticeable loss in hp/tq. That is what you are feeling.
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Old Jul 12, 2007 | 07:25 AM
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I wouldnt drive a car w/o a high flow cat on the street, the smell is horrible and i dont want to have to worry about the $10,000 fine. although i get a tp for the track
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Old Jul 12, 2007 | 07:28 AM
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Originally Posted by justboosted02
I wouldnt drive a car w/o a high flow cat on the street, the smell is horrible and i dont want to have to worry about the $10,000 fine. although i get a tp for the track
I havent noticed any of this "smell" in 72,000 miles

Maybe some people behind me on the road have
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