Turbo Buick Forums banner
1 - 7 of 7 Posts

·
Registered
Joined
·
1,752 Posts
Discussion Starter · #1 ·
I have been tuning with my new Extender chip and the car runs very well. It has 23*/21* timing in low/high gear. I am running 93+alcohol (SMC kit) at 20-21# boost. Only concern I have is that my EGTs (SMC) are in the 1610-1630 range but the O2s are 792-810 range with 0.0 knock retard. These numbers are for a 1/4 mile street run. Should I worry about the EGTs since the O2s and knock retard look good? Thanks.

------------------

Jim Anson, 87 GN with: TA-49; 50# injectors; 62mm Hemco; 3" DP; Walbro 340; CAS V-4; and SMC alcohol system. Stock long block, transmission, and converter. Best run of [email protected] with JL 110 chip, 110 octane and 23# boost.
 

·
Premium Member
Joined
·
43,735 Posts
The o2s are not a very reliable indicator as you get close to the edge. The sensor is neither accurate nor linear as you depart from its midpoint.

EGTs are much more meaningful BUT, until you know where detonation begins, you don't know much as each car and its combination will differ.

You need a knock alarm and a scan tool to monitor retard resulting from detonation.

Once you have leaned down to the point of the onset of detonation, back off and leave yourself some margin. Some cars may run better a bit richer than the leanest safe setting so do a little playing.

If the car pops but does not show retard, it is still too lean so richen it up or find a way to pump more fuel.


------------------
------------------
Steve Wood

Growing old is mandatory; growing up is optional.


86 GN bought new, 87 T-type-81 El Camino with GN drive train-basically stock 86, 94 Caprice 9C1, 69 SS396 Camaro Convertible
 

·
Registered
Joined
·
1,752 Posts
Discussion Starter · #3 ·
Steve,

Car runs great, no popping. I have a Fast Freddie's knock detector and it is not indicating any major knock. My T-link shows 0.0 knock also, but I was concerned with the high EGTs. I will just increase boost a small amount and see what happens with knock. Agree?

------------------

Jim Anson, 87 GN with: TA-49; 50# injectors; 62mm Hemco; 3" DP; Walbro 340; CAS V-4; and SMC alcohol system. Stock long block, transmission, and converter. Best run of [email protected] with JL 110 chip, 110 octane and 23# boost.
 

·
Premium Member
Joined
·
43,735 Posts
yep, that is the thing to do....bit dependent upon the guage as well as the combo. you could add a couple of pounds of fp and then increase the boost and if all is still good, lean down a bit.

More than one guy runs closer to 1700 on the digital meters but I prefer to find the edge and then back away for some safety margin.

I believe in ZERO retard for long head gasket/engine life. There are those that believe that a couple of degrees won't hurt but when you are pushing a lot of boost..........bang!
 

·
Registered
Joined
·
1,752 Posts
Discussion Starter · #5 ·
I will pump up FP a bit and try one pound more boost and see if I can still keep 0.0 knock retard. Thanks.
 

·
Premium Member
Joined
·
43,735 Posts
always try to start rich and then come down once you have established no knock with a given boost.

Better to leave a tenth in it than to leave the engine in the middle of the track.

I don't get paid to drive mine, but I have darn sure paid to drive it. Nice to keep it cheap!
 

·
Registered
Joined
·
1,752 Posts
Discussion Starter · #7 ·
Great advice. Thanks again.
 
1 - 7 of 7 Posts
Top