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Discussion Starter · #1 ·
I have an 03' Cobra with the following mods: 9" K&N clamped to mass air, L pulley, 2 1/2 " flowmaster cat back and a dyno tuned autologic chip.

Car is YDHO 2nd run car

My dyno results after the tune were 428 rwhp & 439 rwtq sae.

Before the tune the car was way lean....to the tune of like 16.0-14.1

After the tune it was down to 14.1-11.5

The car did 425 rwhp before any tuning(way lean) but I gained as much as 68 rwtq at 2600 rpm's after the tune.

Some questions I have are:
1. do these #'s sound low to anyone else?
2. with a vaccume guage hooked up my peak boost dropped from 12.9 to 11 at higher rpm. Is this from the stock belt slipping or something else?

*We tried increasing and decreasing timing with no gains in h.p. or tq..
*Car still has the factory plugs gapped at what ever the factory decided to gap them at.
*Car has 1300 miles on it.

What do you guys think???
 

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If you are only seeing 12#'s of boost with the 2.93 pulley.....you are getting MAJOR belt slippage. Is there black stuff around the pulley guard? What belt are you using? Get the right belt and the SFPHQ 100mm Idler Pulleys and watch the dyno #'s rise, rise, rise :)
 
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your still about 3 points lean. are you getting the ses codes? was the wide band analyzer in the form of a bung welded into the exasut or a stick in the tail pipe jobbie?

here is the cure
1-414-404-1413
 

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Discussion Starter · #4 ·
SVTVenom said:
If you are only seeing 12#'s of boost with the 2.93 pulley.....you are getting MAJOR belt slippage. Is there black stuff around the pulley guard? What belt are you using? Get the right belt and the SFPHQ 100mm Idler Pulleys and watch the dyno #'s rise, rise, rise :)
I'm pretty sure the pulley is a 3.10(I thought that was the lightning size). I will have to measure it to be sure.

I am actually getting 12.9....almost 13 peak.

I still have the factory belt(tensioner reads just on the edge of O.K.)on but have a gatorback 74.5 I got yesterday to put on.
 

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Discussion Starter · #5 ·
matt lankford said:
your still about 3 points lean. are you getting the ses codes? was the wide band analyzer in the form of a bung welded into the exasut or a stick in the tail pipe jobbie?

here is the cure
1-414-404-1413
Ses codes??? Not sure what that is.

Tail pipe sniffer.

The 14.1 # was right at 2500 where the dyno reading starts and drops quickly to low 11's
 

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trmn8r said:
I'm pretty sure the pulley is a 3.10(I thought that was the lightning size). I will have to measure it to be sure.

I am actually getting 12.9....almost 13 peak.

I still have the factory belt(tensioner reads just on the edge of O.K.)on but have a gatorback 74.5 I got yesterday to put on.
The Lightning pulley is a 2.93. You are slipping if you have the stock belt. I've seen guys here in Dallas with the 2.93 pulley seeing around 14-15#'s with all the cold air we have had. Slap the new belt on there and see what she does.
 

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Discussion Starter · #7 ·
I got the new belt because I am getting black dust on the blower snout and on top of the engine. I figured it must be from belt slippage.

Is the 74.5 the correct belt if I do have the 2.93?? I plan on changing it this weekend.
 

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trmn8r said:
I got the new belt because I am getting black dust on the blower snout and on top of the engine. I figured it must be from belt slippage.

Is the 74.5 the correct belt if I do have the 2.93?? I plan on changing it this weekend.
According to SFPHQ, the 74.0 is the belt for the 2.93 and the 74.5 is for the 3.10 pulley. You could probably still use the 74.5 but you will still have slippage. Get the 74.0 belt and the SFPHQ 100mm Idler Pulleys and you won't have to worry about any belt slippage at all.
 

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Discussion Starter · #10 ·
SVTVenom said:
According to SFPHQ, the 74.0 is the belt for the 2.93 and the 74.5 is for the 3.10 pulley. You could probably still use the 74.5 but you will still have slippage. Get the 74.0 belt and the SFPHQ 100mm Idler Pulleys and you won't have to worry about any belt slippage at all.
If indeed I do have the 3.10 pulley would these dyno #s sound more accurate?

I will measure the pulley before I install the belt and get the correct one if I do have the 2.93.
 

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trmn8r said:
If indeed I do have the 3.10 pulley would these dyno #s sound more accurate?

I will measure the pulley before I install the belt and get the correct one if I do have the 2.93.
I'd say your #'s are about right if you had the 3.10 pulley, K&N, Flows, and chip.
 

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here is the cure
1-414-404-1413 [/B]


Absolutely Agree! Call this number, your problems are over:D
 

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Discussion Starter · #14 ·
I think I can guess by Matt's sig where that phone # gets me.

What problem do you think I have that would be corrected without doing any more mods?

Do you think the tune is off and costing me hp & tq with the mods I have?:confused:
 

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Discussion Starter · #15 ·
Anyone else have some thoughts on this??

I plan on measuring the pulley, and if it is the 3.10, changing the belt this weekend. If it is the 2.93 I will get a 74 belt instead of the 74.5 that I have.
 

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Discussion Starter · #17 ·
chillfactor said:
Post again after you measure, change belt, and check boost. Than we can help......if not, call the number.
Gotcha!!

Got to get calipers out to measure pulley.......if 3.10 change belt....if 2.93 get new 74 belt and change......making mental notes.

Thanks for the help!!

I will get this done and be back with probably more dumb questions.:eek:
 

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Discussion Starter · #19 ·
OK....... here is the scoop. I pulled the stock belt off and measured the pulley.......sure enough it's a 2.93 not a 3.10 like I thought. The belt I had gotten was a 74.5 so that's on it's way back this morning and a 74 is on the way.

While I was under the hood I pulled a spark plug to see which one it had. The stock plugs are AGSF22FM1 and the one I pulled is gapped at .44 .

Now the questions:
1. I checked the boost when the car was on the dyno and the highest it went was 12.9 and dropped to 11 in the higher rpm range. I have seen guys post they are seeing 15 out of the 2.93....is my low number from the stock belt slipping that bad?

2. From the posts I have read on here it looks like I should be doing something different with my plugs. Please keep in mind that I don't have a problem paying more for plugs that will last longer.f this matters or not the car gets driven in temps ranging from 20s-100. Which plug would you suggest and how should they be gapped?

3. After I change the belt and plugs will I need my chip re-burned?

I am really disappointed with my dyno #s now knowing I have a 2.93 pulley. I sure hope the belt and plugs get the #s up.

Where do you guys think my dyno #s should be? Again I am currnetly at 428 rwhp and 439 rwtq SAE.

Thank in advance for all of the great advice. The wealth of knowledge available from this board is fantastic!!:D:
 

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Discussion Starter · #20 ·
BTW There was no detonation evident on the dyno pulls we did. Nothing on the graph or by sound to indicate detonation.
 
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