Horsepower has escaped

[Brickell gt500]

The car: 2013 GT500 approx 5,000 miles when I first modified on it.

Mods: upper pulley, off road x, vmp 67 tb, air tube (not big air)

Result: Hot summer day on the dyno 689 hp / 696 tq.

Car now has 23,000 miles

Updated mods: JLT 123 mm , new tune

Result: cool October day 669 hp / 689 tq. Negative 20 hp/ negative 7 tq.

I put the old intake back on the car and it made even less. Where has the hp gone? Same tune, same dyno, and drastic changes in hp. Put in new plugs didn't help.

The boost seems consistent on the dyno. However, the stock gauge will only reach a max of 12 psi with the JLT 123. It would reach 18 psi with the carbon fiber tube.

Any suggestions on how to regain the lost horsepower?

 

[5.8 Venom]

Same dyno, fuel, etc?

 

[07 Black Beauty]

Did have A/F and timing checked while on the dyno or were these just HP power pulls?

 

[Brickell gt500]

Same dyno and 93 octane both times.

The tune was updated for the JLT 123mm

 

[JAJ]

Put a new belt on and try again.

 

[CodyK7]

Could be belt slip. Is there any black dust around the snout of the blower. Did they measure the boost when dynoing ? You said there is a new tune. The new tune could be less agressive. You could data log and ask the tuner.

 

[VNMOUS1]

The car: 2013 GT500 approx 5,000 miles when I first modified on it.

Mods: upper pulley, off road x, vmp 67 tb, air tube (not big air)

Result: Hot summer day on the dyno 689 hp / 696 tq.

Car now has 23,000 miles

Updated mods: JLT 123 mm , new tune

Result: cool October day 669 hp / 689 tq. Negative 20 hp/ negative 7 tq.

I put the old intake back on the car and it made even less. Where has the hp gone? Same tune, same dyno, and drastic changes in hp. Put in new plugs didn't help.

The boost seems consistent on the dyno. However, the stock gauge will only reach a max of 12 psi with the JLT 123. It would reach 18 psi with the carbon fiber tube.

Any suggestions on how to regain the lost horsepower?

Silly question, but since it's the "same tune" the transfer function was likely manipulated. If it was, the load will be different and the on-board boost gauge will read differntly.

Do you have a datalog from the pulls (that's the really silly question because 90% of the time the answer is no).

bj

 

[BOSSPOWER]

Double post.

 

[BOSSPOWER]

My good friend, as we have talked...try in this order, one at a time or all three if you want (remember the boost ghost that we spoke about, it does exist and the dyno will not show it);

1. Green or blue belt
2. BPS Auxiliary tensioner
3. Thump Racing tensioner

 

[sb03cobra]

Stock clutch?

 

[BOSSPOWER]

Stock clutch?

Yup.

 

[Beercules]

Try some bg 44k. Get the carbon out of the heads. Then change the oil. It might only be placebo effect, but it seems to have made noticeable differences in my past cars. (Not enough miles on my gt500 yet).

 

[Ky GT500]

Carboned up O2 sensors can mess with HP also. Mine went out around 7-8K,,,but I'm also running LT's and no cats. Just a thought.

 

[2011 gtcs]

Your clutch could possibly be slipping a tiny bit up top. But like everyone else has said, get a blue belt cause your more than likely getting some belt slip.

 

[Brickell gt500]

Thank you for your responses. I will be attending the Ocala 1/2 drag races. I just want everything to be running at 100%.

 

[wantedGT500]

As others have said, either belt slip or clutch slip. Either will rob HP and TQ. Happened on my previous cars which made 90% of the torque below 3k due to DI.

 

[VNMOUS1]

Thank you for your responses. I will be attending the Ocala 1/2 drag races. I just want everything to be running at 100%.

we'll be there. come see us.

 

[MattR]

we'll be there. come see us.

What he said, VMP will take care of you.

 

[Van@RevanRacing]

Brickell GT500

If you want to truly enjoy the Ocala 1/2 Mile event I would recommend having this issue identified and remedied prior to the 1/2 mile event or you're going to be wasting your hard earned money on your entry fee and driving back and forth to the event.

Logistically if the car is data logged properly while on the dyno or on the street with the correct PIDS selected you can easily identify areas that can cause horsepower loss or reasons for horsepower loss. i.e. knock sensors, commanded wide band O2's not trimming correctly etc. etc. etc.

Van

 

[Brickell gt500]

My apologies for rehashing a old thread. Some time has passed and was seeing if anyone has experienced this? Basically, losing hp over time. Thanks.