This is topic MY GIRLFRIEND'S DYNO RESULTS 97 Cobra S Trim in forum Tech Talk at Northern California Ford Owners  .


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Posted by 85GT (Member # 1695) on :
 
My girlfriend got her cobra rebuilt at HCI. We took the car to get dyno'd today. On a Dynojet with A/F at 11.5:1 and i believe 20 or 22 degrees total timing she put down 402hp at the wheels! And 358 lb ft torque! Not bad for a daily driver huh???
 

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Posted by DV92Camaro (Member # 2739) on :
 
really good numbers
 

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Posted by FoX GT (Member # 4587) on :
 
looks like you got what your were lookin for!


 

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Posted by Blue Oval (Member # 2548) on :
 
HCI!
Nice #'s
 

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Posted by 1FAST93COBRA (Member # 4756) on :
 

 

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Posted by JohnB (Member # 969) on :
 
What sort of psi is it pushing?
 

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Posted by BlackNGold (Member # 655) on :
 

quote:

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Originally posted by JohnB:
What sort of psi is it pushing?

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yeah, and is this with an aftercooler?....What kinda rebuild was it?....Isn't that what a stock 4V with a few bolt ons would hit?...What her combo??...

[ October 20, 2004, 07:43 AM: Message edited by: BlackNGold ]
 

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Posted by 1Sicgt (Member # 714) on :
 
Is it me, but isn't the torque number low????
 

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Posted by BlackNGold (Member # 655) on :
 

quote:

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Originally posted by 1Sicgt:
Is it me, but isn't the torque number low????

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It's not you....

For a built motor (not knowing what combo is being run) those numbers seem low....
 

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Posted by NO MANRZ (Member # 566) on :
 
That is horrible for a s-trim and a built motor unless it huffing 6-7 pounds. Let me guess 8.5 compression... big mistake.
 

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Posted by 1fast281 (Member # 4670) on :
 
Even for 6-7 pounds that is not good. A 100% stock engine 4V engine should be making over 400rwhp with an S-Trim.
 

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Posted by HungryHippo (Member # 537) on :
 
building a stout bottom end does not add power
 

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Posted by Mr JoCo (Member # 1549) on :
 
So your girlfriend smokes you?

quote:

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Originally posted by NO MANRZ:
That is horrible for a s-trim and a built motor unless it huffing 6-7 pounds. Let me guess 8.5 compression... big mistake.

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quote:

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Originally posted by Mr JoCo:
So your girlfriend smokes you?

quote:

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Originally posted by NO MANRZ:
That is horrible for a s-trim and a built motor unless it huffing 6-7 pounds. Let me guess 8.5 compression... big mistake.

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why is low compression a big mistake?

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quote:

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Originally posted by Mr JoCo:
So your girlfriend smokes you?

quote:

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Originally posted by NO MANRZ:
That is horrible for a s-trim and a built motor unless it huffing 6-7 pounds. Let me guess 8.5 compression... big mistake.

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why is low compression a big mistake?

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You want to keep the compression on these dinky motors as close as you can to stock. So around 9.6-10:1 is great. The main reason for this is to keep the very little torque these motors make. Why would you make a motor with no torque even worse.

From only the fastest supercharged 4 valve drag racer, not bench racer--

Reducing compression a full point means a significant loss in torque.

Example:
Vobra with 12 psi nets 500 rwhp and 440 pounds of torque
8.7:1 compression with the same combo now means the car makes 450 rwhp and 390 pounds of torque.

If our same cars had 5.4's I would say lowering the compression wouldn't be a big deal because there would still be more torque than horsepower. It wouldnt have as drastic affects as it does with a 283 CI 4V Mod Motor. It's the combination of small cubic inch displacement, and cylinder head design that require the higher compression to optimize the efficiency of the motor.

If you can live with less power and slower numbers at the track and added insurance is more important than optimizing the overall performance I would then say lower compression would be the way to go. I would recommend an 11cc dish maximum though no larger.

PRO's
1. More protection against detonation (Pre-ignition). This means you may run about 2-3 degrees more timing per giving octane than stock compression. If your tuner does not put the proper fuel curve into the tuneup you will still blow up. If you run out of fuel you can damage the entire engine regardless of compression ratio. Running an intercooler that can reduce air inlet temps about 75 degrees colder will have about the same amount of detonation protection.
2. Running a dish piston allows you to sometimes run a higher lift camshaft and not worry about piston to valve clearance. However with a 4V Cobra engine, you never have to worry about that anyway because you don't run a ton of lift.

Cons
1. 40 to 55 pounds of torque loss can mean as much as 5 tenths and 5 mph in the quarter mile. Or if your racing your buddy it could mean you are at a 5 to 6 car length disadvantage.
2. Less Torque means the car simply will not accelerate as quickly.
3. 40 to 55 pounds of torque is hard to make up. Think about some of the mods it takes to get 40 to 55 pounds of torque back. Some examples are.
a. Adding 5 to 8 pounds of boost (depending upon the efficiency of your power adder)
b. Removing about 500 pounds from your car.
c. Adding an air to water intercooler and adding more timing to your tuneup.
d. Getting extensive head porting and matching billet camshafts.
e. Adding a 30 shot of nitrous.
f. Adding about 30-35 cubic inches.


[ October 21, 2004, 02:55 PM: Message edited by: NO MANRZ ]
 

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Posted by Mr JoCo (Member # 1549) on :
 
so if he was boostin about 20lbs then it's a good idea?

Thanks for the info, cleared a lot of stuff up. Still got some questions but for the sake of this thread I'll save them for next time
 

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