Injector Duty cycle calculations

[timsiford at hushmail.com]

>My current setup is !ENGINE.  The last engine I was running had 30lb
>injectors (93 Lt1).  

Doh!

>And if you are using tunercat, at least on the 93 LT1 his injector
>constant is off.  

I am using TunerCat for the 730 ECM.  I have verified that the injector 
constant is on the money (at least with the 'H' version of the .tdf file 
and greater).

> The best on this motor was a
>12.52 at 110.4.

Money.  That is really close to what I want to be running in the mph category 
with the MiniRam ... just a tad bit more ET though.

> will be a 409LT1 SBC, with a 230/244-112 cam.

Holy shit man.  A man after my own heart.  I am trying to come up with excuses 
for building a stroked 400 small block (420ci).  That engine is going to 
rock.

>Running to higher rpms make more of a requirement of injectors, since
>higher rpms mean less time to be open.  If his peak is alot lower than
>yours is then that would do it.

I would actually think that his peak HP is higher than mine.  He is running 
the 224/236 -112 cam and I am running a 218/224 -112 cam.  He also has a 
phat exhaust (long tubes, 4" mufflex).  I have crappy 1-5/8" shorty headers 
and flowmaster 3" catback.

>What kind of times are both cars running? 

His car is a beast.  12.01 at 117+.  All naturally aspirated on the stock bottom 
end
Mine ran 12.58 at 108 all natural on the stock bottom end.  

His injector pulse widths are 10-11ms at 6000+ RPMs as reported by Diacom 
and he has an SEFI engine.  Mine are 8.5ms at 6000+ RPMs as reported by 
Diacom and I have a batch fire engine.  

Later
tim


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