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LT1 CMC-er needs some help!!!


Keith

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I just got back from my dyno test. Too much power. I progressively covered the air filter with duct tap up to about 66% of the area with a little reduction but not much.

 

Without duct tape, I was making 268hp/29xtq (forget) and the final pull I had 261hp/294tq.

 

My only changes from stock are:

Underdrive pulley

1LE Elbow (actually, one could argue it is stock)

K&N air filter

SLP Y-Pipe and Cat

3" cat-back, no muffler

 

The dyno shop suggested that if I remove the underdrive pulley it should be worth 8-10hp, the removing 1LE elbow should be good for about 3hp and replacing the K&N with a crap filter could be good for 2-3.

 

How does one figure out the proper size for a TB restrictor plate and hos can I get one quickly!??? I have less than 2 weeks... Crap!

 

See sig for a scan of the last dyno pull....

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Get one of the restrictor plate sets available in the For Sale forum and keep swapping them until you're under the HP limit. Looking at that torque curve leaves me just shaking my head and wondering why LT1s are legal in CMC.

 

At least your Camaro is about 500 pounds heavier than my Mustang!

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Ahhh, Matt. Now you now why I'm a GM guys. I am a torque JUNKIE.

 

Yeah, you hit the nail on the head, too, I've got torque but I've also got girth to overcome. It actually makes the f-bodies and Mustangs interesting playmates on the track because each will shine in certain sections of a given track... With even drivers, lots of close running and passing.

 

I gotta get a restrictor plate that works or I am stuck in AI!

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Since your car is already so heavy, why don't you just take the 100 pound penalty and run up to the 257hp limit. I'm sure taking off the underdrive pulley and maybe replacing the K&N with a stock filter would drop the extra 4-5hp.

 

I like torque too, so I think 95 Cobra R clones should be made legal in CMC.

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Yup, you need a restrictor!

 

I pulled 255/303 without a restrictor, and with the 37mm I did 233/301. I'm definitely running the heavy weight right now (though you got me by a few pounds or so). I guess I could take out the Rockford Fosgate speakers.

 

For every 10 pounds overweight you can add 1 h.p., up to 5. Same for the tq. BUT, they are computed seperately. So if you're 251/301, that's a 20 pound increment. The 6th and 7th hp/tq are big weights, so I'd avoid them if possible.

 

The underdrive pulleys are adding to your HP numbers, not so much tq. But you should really have one at least on the power steering unit to slow it down. Maybe just remove a few? Because of the limits we have, other than the PS one, they're really un-needed...

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Since it takes 5 minutes to swap in a restrictor plate when the time comes, I'd say take the 100 pound weight penalty for now (you're voluntarily carrying it anyway) to at least run up to the 257hp limit. Since you're already under 300 lb-ft, that's not even an issue. Then figure out how to dump a couple of hundred pounds out of the car and put the restrictor plate in when you are able to run at minimum weight.

 

Speaking of minimum weights, can anybody explain why the minimum for Mustangs was raised by 25 pounds this year?

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dayum! my car w/ a bone stock motor of unknown history and 78K on it made 285/325 unrestricted. it had an underdrive pulley and a 1LE elbow. a borla Y pipe and a bullet muffler. it took the smallest restrictor (31mm) to get me below the 230/300. i'm currently 220/280 so i had a 32mm restrictor made to try and get to the limit.

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A couple of people have suggested that I take the weight penalty - maybe I have mis-undersood the rules, but I thought the hard maximum for LT1's is 257/307. Am I wrong?

 

Still looking for TB restrictor plates!

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Keith,

 

You are correct. The hard maximum, is 257HP or 307 lb/ft. At those power levels, the car and driver would have to come off the track weighing a minimum of 3580 lbs.

 

Matt,

 

The weight of the Mustangs was raised 25 lbs to help level the playing field. A couple of years back we drop the weight by 75 lbs in an attempt to make the Mustangs more competitive. 75 lbs worked a little too well with the Mustangs dominating the win column in 2004.

 

Mike

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