2 years ago, some of you will remember I put down 405rwhp and 365rwtq with a GM847 cam and Advacned Induction "Econoport" LT1 heads, full exhaust and every bolt-on. This was through a T56 with and the stock 10-bolt.

I've since switched over to a 4L60E with a Vigilante 3500 stall converter but I still have the same engine, exhaust, rear-end, 93 octane and PCM tuning. The new dyno results are 368rwhp and 354rwtq. So thats a 37hp loss and 11ft/lbs of torque.

Previous best at the track with the T56 was 12.189 @ 116.64mph with a 1.874 60ft. But most of the time the car ran 12.3x @ 116mph. The last trip to the track with the 4L60E I ran 12.106 @ 112.42mph with a 1.68 60ft. Same type of tires, vehicle weight and weather conditions. However this time the car was alot more consistent. it ran 12.18, 12.17, 12.16, 12.15, 12.14 then a 12.10 on the last run with 60fts from 1.66 to 1.71

My goal was to get the car deep into the 11s with the heads and cam and I know I can. I have a crappy y-pipe and I picked up 11hp and 20ft/lbs of torque by running open headers on the dyno. also, it was running too lean at 14.0 A/F ratio and pulling out timing. And also with 4.11s I'm shifting into overdrive around the 1000ft mark and the car doesn't want to accelerate. This winter it gets a new rearend with 3.73s, full BMR suspension, QA1 shocks and drag springs, new exhaust and higher stall converter. I've got tunercat for the car and since I work part time for a dynoshop I have free unlimited access to a dyno so I can get the tuning right on.

I'll have this car running mid to low 11s next year

 

I have been wondering for a while which combo would be FASTER. Thanks for posting this........it helped me make my mind.

 

On the dyno you will lose hp becuase of the stall converter. I love my stock auto

 

if you would have drop thesoe 60s to 1.67 with a 6 speed like you did with auto you would be in the 11s probaly 11.8x somehting

im glad to see a acctual test.

thanks.

 

What a big difference. Now I'm not too unhappy with my 389rwhp/380rwtq (started run at 3800rpms, well above the flash point) in my stalled auto, BABY cam, LE headed, stock bottom end setup. I wonder what my motor would've done with a 6 speed. By the looks of the times, you could DRIVE that 6 speed.

Thanks for the post, very informational.

 

Leave the 4.10's in the car, put a taller tire on it.



David

 

Thats what I was thinking about.

I swapped my 2.5" Y-pipe for a 3" one and picked up 4rwhp and 4rwtq then dynotuned it and got my numbers up to 389.2rwhp and 364.7rwtq, SAE corrected naturally. Thats a 21hp gain