Changed converter same 60'

[GTAmuscle]

Bought a Circle D 3C, changed input shaft, PA extended pan, TCI servos, changed from a bama tune to a Lund tune... And I'm getting almost exactly the same 60' as before. 1.89 vs 1.90. Albeit the air here in pittsburgh isn't as good as in Louisiana but to get the same 60' is just baffling. Any input is welcome.

 

[KrisR]

You had a stock converter before, or?

Can you post a couple before/after timeslips for comparison?

Not spinning?

 

[GTAmuscle]

Before with stock TC
Right lane

After with Circle D 3C
left lane
No spinning.

 

[KrisR]

Hmm. Not sure. I certainly would have expected an improvement. I mean the whole run is obviously off a little from before but even with a worse DA I would expect a much better 60'. How does the car feel? Did you experiment with flashing it from idle vs stalling it up against the converter, etc?

 

[GTAmuscle]

Car feels fine from beginning to end just completely in shock that this $1200 piece of billet has helped zero.
I launched from idle and got a 1.93 and launched from 2300 (where it started pushing hard) and got the 1.90 you see there

 

[GTAmuscle]

Hm, just checked the transmission fluid level and it is significantly over the "safe" zone. I calculated I would need about 15 quarts of ATF when I dumped it but perhaps not all of it got out of the system. This could lead to it locking up prematurely correct?

 

[psfracer]

As mentioned the whole pass is off (I am assuming the 1.90 is after, and the 1.89 was before?)

The old set up was better at every incremental. The true story also is the 106mph you had vs the 103 mph you have now.

Was there a huge difference in DA? To loose .25 and 3 mph by the 1/8th is pretty concerning.

 

[GTAmuscle]

The DA was -800 on the good run and about 1800 on the run last night. I loaded the tune from bama that ran the 12.814 and despite not being tuned for the TC ran a 13.048 with a 1.88 60'... Lund is getting a call tomorrow and my dumbass is emptying the pan a little bit.

 

[CPRsm]

Don't stall so high next time. Try 12-1500 and hit it. Converters multiply torque below their stall rating. You're not hitting the tires very hard if you stall as high as you can, the to. Give the engine a running start at the converter. See if that helps any

 

[GTAmuscle]

I still think the biggest problem is that the transmission is overfilled

 

[Five Oh Brian]

2600' swing in DA is a huge difference. 3C doesn't really flash that much higher than stock, too, so a 5C or bigger would have generated a noticeable improvement.

 

[CPRsm]

I still think the biggest problem is that the transmission is overfilled

Other than leaking out the vent tune idk of any side effects that could cause performance problems

 

[Swarzkopf]

I can't see how over filling the transmission would cause the converter to stall early.

It's probably the air here - Pittsburgh Raceway Park is a pretty slow track compared to the national average. Last night was pretty humid too.

Even with stock 3.31 gear, my 5R55S car went from 1.83 60's to routine 1.6s by going to a 3200 stall PI converter. Made a huge difference.

 

[Brezick]

I can't see how over filling the transmission would cause the converter to stall early.

It's probably the air here - Pittsburgh Raceway Park is a pretty slow track compared to the national average. Last night was pretty humid too.

Even with stock 3.31 gear, my 5R55S car went from 1.83 60's to routine 1.6s by going to a 3200 stall PI converter. Made a huge difference.

This. Where was the first track? PRP is a good .2 slower than many other east coast tracks.

I dont have exact numbers because when i did the converter, i did DR's also, but I did 12.23 with the stock converter and with converter and DR's, that dropped to 11.7

 

[GTAmuscle]

First track was State Capitol Raceway in Baton Rouge, LA. Also a slow track due to the outstanding humidity and heat.

 

[Swarzkopf]

-800 DA...can't be that slow. I've been racing at PRP for over a decade and have only seen negative DA once, and it lasted for about an hour. LOL

 

[GTAmuscle]

That was in the middle of winter and they're legendary for horrible track prep.
Either way that doesn't solve the mystery on my 60'. It should be cutting a 1.7x at least.

 

[Brezick]

-800 DA...can't be that slow. I've been racing at PRP for over a decade and have only seen negative DA once, and it lasted for about an hour. LOL

Lol, last friday night was the best DA i ever seen there, even with 100% humidity, it was only about 100 DA. I still made faster passes elsewhere with 1500 DA.

OP, you said you also changed tunes, can you switch back to the old tune and then run a comparison? Maybe the new tune is more conservative.

 

[GTAmuscle]

Lol, last friday night was the best DA i ever seen there, even with 100% humidity, it was only about 100 DA. I still made faster passes elsewhere with 1500 DA.

OP, you said you also changed tunes, can you switch back to the old tune and then run a comparison? Maybe the new tune is more conservative.

Yes I did. Switched back to the old tune and ran a 13.048. 60 was still a 1.88 though.

 

[Swarzkopf]

That was in the middle of winter and they're legendary for horrible track prep.
Either way that doesn't solve the mystery on my 60'. It should be cutting a 1.7x at least.

I disagree- your trap speeds were also down at every marker on the PRP timeslip vs the slip you posted from Louisiana. Lower trap speeds indicate that your car was making less power (probably due to the shitty air). Less power = worse 60'.