Alright it time to figure this out. I was running 13's in the 1/4 mile in 85 degree weather and very humid. I decided to get a tune, upgrade my injectors to 42lb's and remove the fmu. I did all this and on a 50 degree day i ran a 16 second time. Absolutely nothing else changed with the car and it has mostly been sitting with a weekend drive each week. I did the email tune and sent him the datalogs and he says they look fine and doesn't think anymore tuning is necessary as all the numbers look fine except for an occasional knock up to 4 degrees. He thinks its false knock since it goes away so fast. Obiviously something happened and it wasn't gaining 15 hp like many claim from a tune. The engine is 100% stock so what might cause my issues that i could check to solve this mystery?

 

Why would you run 42lb injectors on a stock motor? Seems to be the problem to me can't say about the tune don't know what was "tuned".

 

With the supercharger im getting 75% injector duty cycle and this is with the car making way less horsepower so the injectors are not really that much bigger than i would need. If i understand correctly its when there too small that the problems happen.

 

I think he thought when you said "100% stock motor" you meant that the motor was stock. That's what I thought too until your second post.

There's no such thing as "degrees of knock." If your datalog shows knock retard that will certainly slow you down so get that fixed.

Do the datalogs you're sending the tuner include a wideband?

A mail-order tune with a supercharger seems pretty scary to me...

 

how much timing is being pulled with the MSD box,depending on the amount vs. the amount in the TUNE you may have too much timing retard.
42lb injectors are perfectly fine for a low boosted Lt1. the duty cycle is good,you need more injector when you are in the 90% and above area..

 

I tried turning up the retard control and quit both runs short of the 1/4 mile because it felt like i was running very lean and power was almost gone. The run with the dial turned to zero is my best run but still down on power. Does the box retard timing even if i leave the manaul control on zero? It feels like the timing is part of my problem but its hard to say. I don't know if the tuner pulled timing when he did the tune. Maybe the car doesn't need any pulled but put back. Is there a way to tell?

 

The box multiplies the boost times the **** setting, to arrive at the degrees of retard. If you dial "0", the spark retard from the box will be "0".

 

You dont have the car tuned for a supercharger with out one on the car do you?

 

Yes... he has the S/C installed. Check the mod's list. Its confusing. Apparently by "100% stock" he meant stock rotating assembly, heads and cam.

If you are running 75% DC on 42# injectors, you would be making 420 flywheelHP (assuming a fat BSFC of 0.60 #/HR/HP). That would be 145 HP on top of the stock engine's 275 flywheel. I don't see 6#, no intercooler making any more than that. If you were making 420 flywheelHP, you would be running low 12's. 16 seconds in a 3,700# car would be less than 200HP. You have serious problems. Was there any evidence of a huge black cloud of smoke pouring out the exhaust pipe? That fuel has to be going somewhere, and it definitely isn't being burned to make HP.

 

I'd agree, I've been often thinking about why his car isn't performing well, because my buddy has a firehawk with less mods than him, running 6lbs of boost and that car runs like a raped ape...I'm just amazed at a run of a 16.0, something is definetely not right...

I'm sorry mint, hopefully you can figure out what's going on...?

 

I apologise as well I didn't read sig I went by text in post, again sorry!

 

what did the rest of the run look like? was it a pig out of the hole?
trans is in good shape?
It might be using too much fuel. how do the plugs look?
Where in the 13's were you before the upgrades?

 

The higher 13's previousely and it doesn't appear from the datalogs to be overly rich or lean at any point. I'll check the plugs and see what they look like. It still looses traction on the shift into second and appears to be working fine.

 

So, one more time - you are datalogging a wideband?

 

Found this in another thread, which is what I suspected - you have no idea how it's running, and there's no way for your mail order tuner to know that the tune is dialed in.

Tuning a FI engine without a wideband is beyond scary into just plain dumb.