Crappy 1/4 mile slip

[Dusty Bradford]

I can't remember the timing, it's whatever Eric puts in the alky chip. I'm thinking around 23*

Yes pump and alky.

Going to the dyno tomorrow to see what rpm/mph I am so hopefully we can figure out if the convertor is too loose.

You may not find out much on the dyno. Your brake stall at 0# boost and the rpm drop on the gear change will tell you more.

If you dyno it. Make sure the operator goes into 3rd gear and very slowly rolls into the throttle. The best way to check converter slip is to be at WOT just slightly before your shift rpm. If it kicks down to the lower gear, it will not be accurate because the converter won't have time to couple after the gear change. On a car with a manual valve body you also have to roll into it slow. If you go WOT at a low rpm like you do with a stick shift, the converter will flash and never recover.

 

[jerrad]

Got back from the dyno
HP 365 @4353 at 102mph
TQ 507 @ 3706 at 87mph
These numbers are uncorrected on a mustang dyno.
After 4353 rpm the power dropped off like a cliff. This was at 24/25 pounds with the 02's at 734.

I put the numbers in the calculator and it showed -2.48 slip. I wish that was a posability but sadly it isn't.

 

[jerrad]

Anyone have any ideas?

 

[Dusty Bradford]

Did the 02's drop of at the same rpm??

Could be a sign of weak fuel system. If the pump is maintaining pressure I'd look into the coil pack, ignition module, plugs, plug gap and plug wires.

4300 rpm is a little low for a valve spring issue to cause loss of power unless the springs are terrible.

 

[jerrad]

I'm going to put a new pump in it. I've had the same one hot wired for about 6 years.
I put 43's gapped at a tight 32 with new wires last week.

The valve springs are pretty new. I put the champions on 3 years ago so they should be ok.

 

[johnnyttype]

Got back from the dyno
HP 365 @4353 at 102mph
TQ 507 @ 3706 at 87mph
These numbers are uncorrected on a mustang dyno.
After 4353 rpm the power dropped off like a cliff. This was at 24/25 pounds with the 02's at 734.

I put the numbers in the calculator and it showed -2.48 slip. I wish that was a posability but sadly it isn't.

the car didnt shift into overdrive did it? where did you get the mph reading from?

isnt peak power on a stock car, stock cam, 4200rpm(not that his car is stock by any means, just using as a comparison)... i still say the old bumpstick is in need of replacing! time to go roller

Although Dusty is right to check into the low O2's, could be that the stock inaccurate one wire O2 is indeed inaccurate, but why chance it!

 

[jerrad]

the car didnt shift into overdrive did it? where did you get the mph reading from?

isnt peak power on a stock car, stock cam, 4200rpm(not that his car is stock by any means, just using as a comparison)... i still say the old bumpstick is in need of replacing! time to go roller

Although Dusty is right to check into the low O2's, could be that the stock inaccurate one wire O2 is indeed inaccurate, but why chance it!

The mph reading is off the dyno roller.

I have a new roller on its way so it'll be a few weeks before I install it.:smile:

Once I get the cam in the next purchase is a powerlogger/wideband.

 

[1chance]

This is a very good thread!!

 

[jerrad]

Not for me. lol
I wish it was " My car is running 10.80's and I need a new pair of underwear, what do you suggest" lol