Ok so those who follow me know ive rebuilt my motor gasket matched the intake side of my heads put a windage tray and a light flywheel on with the t-56 and 3.90s So heres the issue. I ran previously mid low 13s and now have a hard time getting the 13s on my slip. i did change a lot of stuff, but all that stuff listed previously doesnt seem like my trap would drop a few MPH.... basically im lucky if i get 100.5 when before i was trapping 101.5-102.75


so im wondering, is it possible i changed enough stuff to need a tune to run right? Because the 60s are ok, the power just isnt there. The only other thing i can think of is the speedo doesnt work right now because the tranny i have is mechanical and my car runs VSS, is there a chance thats detuning the motor? Im just trying to figure out how i put all this better stuff in and im running good 60s and bad traps.... previous best was 13.39@102.75 w/ 2.010 60' and now my best is a 13.9@99.8 w/2.1xx or 13.95@100.2 w/2.07 60' this just doesnt make sense and i dont know what to do and im really angry about it. Maf is clean spark plugs are new, filter was cleans when i built the motor....... any help or ideas.....im thinking i should be trapping at least 102 or better.

 

Are your rims the same?

 

What do the STFTs look like? Also you really need to get a wideband O2 system if you are going to tune properly...

 

Id go get a dyno run in on they dyno you got your old numbers on and have your compression checked on all 8. Did you lower your compression when you built your motor? Did they by chance send you the wrong pistons and youre now down on power because of lower compression?

 

What was the weather like the day you ran? And if you don't know, what was the name of the track you ran at and what date was it?

 

motor was factory style rebuild, no new pistons. (meaning i reused the factory rods and pistons) Compression should be the same, havnt checked it yet though. my best runs were on a colder day, but last night was 60s so very similar. And even on hotter days i never used to have a problem getting 100ish now its like a goal....


STFT is around .9-1.1 typically around 1.0 but thats all the information i can give for that because thats how my sct reads the information. No idea what that translates to. And i wasnt going to tune it, i was going to have it tuned, and i beleive they have a wideband O2. When i raced on my 18s i ran 13.8-13.9ish at 100-maybe 101 max. But with my factory rims which is what i have now, my worst time before all this new stuff was 13.7@101 plus so somthing isnt right....

So i take it that means that my speedo not working wont affect the way the engine runs? I only ask because when i i blew the first center force clutch i put the 5 speed back in for a month, and ran a 13.7 w/ 2.0 60' (still slow in the trap) on a warmer day than last night, then i put the 6 speed back in and have trouble getting 13.9 I cant see that the transmission would add that much parasitic loss? plus the gearing is better in the 6 speed.

 

Maybe you just need to mess with your shiftpoints a bit for the different gear ratios of the t-56.

 

Sounds like the 6-speed isn't better.

I have no idea what's what with stock Mustangs at the drag strip, however my gut associates 6-speeds with road-racing, not burning up 1320 feet of asphalt. Could be way off base with that though...

The SCT 0.9 to 1.1 STFTs are -10% to +10% which is OK, not great but OK. Have you tried disconnecting the battery for 5-7 minutes to clear the KAM? That will clear the learned LTFTs and make the PCM learn them anew.

Beyond that you really need a WB O2 system to get a handle on what's going on...

 

Which T-56 do you have, do you know what the ratios are?

 

well, the battery has been disconnected twice since the rebuild for days so it should be clear. and like i said 1.0 was more typical the others where max and min. Well i will say this much, the car feels faster than when i have the 5 speed. And that was my plan with it, the close ratio 1-4 put my car on peak torque every time i shift where the 5 speed drops me under, which is why i think it feels like it pulls much harder in every gear. I just figured that would make it move faster, dont really see why it wouldnt. In anycase, i was still down on trap speed with the 5 speed in. My previous best was 13.39 and a good amount of solid mid 13s at around 102. then new motor windage tray and flywheel, and same 60 foot times, have a hard time hitting 100.(with the 5 speed) and of course even worse with the 6 speed. the only other thing i can think of was that i put the 3.90s in and had a hard time getting the car to get lower ets, but i dont see how that could cost me .5 and 2mph