Limits of TPI computer

[Mazda Ebrahimi]

Jussi T Kosonen wrote:
> I have the TPIS Insider Hints book that states that stock injectors
> are able to produce +450 HP and they also say that it is better to
> use small injectors with high fuel pressure than bigger ones with
> lower.

I don't know the specifics of the TPI, but this advice is good for two 
reasons. One is that you generally get better atomization of fuel with 
higher pressure.  The second is that going to larger injectors may 
negatively affect your idle.
> 
> I don't know how much HP my engine is producing but taking in a account
> that my cam is so mild I estimate    less than 450HP...
> but that book doesn't tell me what pressure should use.....
> currently I have set it to 45PSI....
> 
> The question is......could I damage my engine at high RMP with
>  too lean mixture..?

It's possible.  But if it happens, it will happen right near stoich. at 
wide open throttle (this is the hottest combustion you can get).  The 
best way to find out is to monitor your O2 sensor as suggested by 
someone else.
There are a couple of other things that may be interesting to check.  
One is your fuel pressure at maximum power, to make sure your fuel pump 
is keeping up with the demand.  When this is the case, you can usually 
tell even by driving the car.

The other is your injector duty cycle.  Generally, you would like to 
keep the maximum injector duty cycle at or below 80% (I think it keeps 
the injector driver chips from overheating, but I'm not sure).  I wonder 
if the ECM will exceed this number if fuel flow demands require it to?
Hopefully someone else on the mailing list has an answer.

Best Regards,
Mazda