When Do I Need To Retune?

[95SvtCobra347]

Hello,

I am new to the group and new to mustang. I have a 1995 cobra that I bought back in April. Everything was already done to the car and it had been dyno tuned. It has a 347 stroker with AFR heads, b303 cam, stock cobra gt40 intake, stock throttle body, aftermarket MAFS, BBK long tube headers, BBK off road x pipe and it had the factory cat back exhaust. The injectors are red. I think they are 30lb injectors by what I've read online but I'm 100% sure. I just changed to a flowmaster American thunder cat back which of course changed the mufflers and also increased the tail pipe diameter. The throttle response is way better and it pulls through the gears faster but I was wondering if the car was going to run lean and need to be returned with this change? I will take all the help and opinions that I can get from the knowledgeable people in this group. Thanks so much

 

[Noobz347]

347 stroker with AFR heads, b303 cam

Have you driven it before? You're lucky to be alive.

It has a 347 stroker with AFR heads, b303 cam, stock cobra gt40 intake, stock throttle body, aftermarket MAFS,

This combo has got to be choked choked choked.

Please post the dyno.

What AFR heads?
What MAF?
What injectors?
What fuel pump?
Who did the tune?

 

[95SvtCobra347]

Have you driven it before? You're lucky to be alive.



This combo has got to be choked choked choked.

Please post the dyno.

What AFR heads?
What MAF?
What injectors?
What fuel pump?
Who did the tune?

Not sure about any of that stuff. I have dyno sheets they show 300hp and 333lbft. I know I have a lot to learn. I am willing to learn and listen with an open mind. This is also only my second sporty rear wheel drive car. I have always had trucks but before this I had a 1982 Oldsmobile cutlass with a mild small block Chevy.

 

[Noobz347]

Start taking pictures of everything in your engine bay and post them up alongside any dyno or build sheets.

You don't really need a tune to change mufflers but you probably sacrificed some performance by opening up the back of the exhaust system.

Google, "Tuned Exhaust System" and you will see what I mean.

 

[95SvtCobra347]

I have no real build sheet I have a ton of receipts. I bought the car from the third owner. I called the phone number on one of the receipts and it was the original owner and he's the one who had all the motor work done.

 

[Blown88GT]

Red injectors are 30's. You don't need a re-tune just for exhaust changes. It has no affect on AFR.

 

[95SvtCobra347]

Red injectors are 30's. You don't need a re-tune just for exhaust changes. It has no affect on AFR.

The car only pulls to about 4700 I was figuring that was because the throttle body and intake are starving the motor on the top end. What is your opinion? It seems like the same thing that happened when I had 305 heads on my 350 Chevy and it was starving because of the small intake runner size it fell off on the top end

 

[95SvtCobra347]

I'm sorry I forgot to thank you for your response. The reply and knowledge that it contained are greatly appreciated.

 

[Dan02gt]

Your combo is definitely choked out, but doesn't really need a tune. You could probably pick up a good amount of power by sending that Cobra lower to Tmoss for a port job, installing a 70 or 75mm TB, making sure your fuel pump is up to the task, and installing a more modern cam.

 

[95SvtCobra347]

Your combo is definitely choked out, but doesn't really need a tune. You could probably pick up a good amount of power by sending that Cobra lower to Tmoss for a port job, installing a 70 or 75mm TB, making sure your fuel pump is up to the task, and installing a more modern cam.

Would the porting and TB mods require a MAFS change or recalibration. I'm sure those mods will need tuned. What is the best way to tune this car. The car has some sort of chip with toggle is What the receipt says