87 buick grand national 6262 bb

[nouseforaname]

This is my first time at the track

8.201 et
87.9 mPh
1.71 60 ft

This run was at 15-16 psi and pump gas and meth injection. The car ran lean in third and more boost had to wait . It was 30 C with high humidity 80%. Also at 2500 m elevation. Once tuned for more boost like 25-28 psi what times can be expected. Also running a down pipe cut cause it to run leaner?

 

[nouseforaname]

Cut out I meant

 

[dpasadena]

...........

 

[Reggie West]

Usually when you open the cut out you run more boost because there is less back pressure. Which also means if your tune is not right you will be leaning out the motor and that can lead to bad things.

 

[V6POWER]

What is your combination?

My car has the 6262 jb. See sig. for combo and time.

 

[nouseforaname]

I'm starting my tuning I'm shooting for low 7's . It should be cooler at a lot lower elevation. 25-28 psi with 12 a/f should satisfy my temporary goals

 

[Reggie West]

First off if your tune is not right at 15 psi it's not going to bet better at 27 psi. You will pop a head gasket or worse.

Second you shooting for an AF ratio of12 to 1 is too lean. At 10 psi you can run an AF of 12 to 1, 13 psi shoot for 11.5 and 15 and above 11 to 1. You may have to run a little richer above 20 psi, say 10.5 to 1.

That will keep the motor together and I highly recommend setting the timing advance to 18 degrees and leave it there until you get the AF ratios correct.

Good luck.

 

[nouseforaname]

Sounds good I also have meth . That would allow a more leaner 12-1 yes or no?

 

[V6POWER]

I run 10.8 afr when spraying methanol. 12:1 will be way to lean.