PSI level of fuel injector?

[kenvw]

My car is having some mods done to it and it seems that the mixture ratio is running very rich. The mechanic tells me the psi on the fuel injector is reading at 60 psi, and according to DC the level should be 55 psi plus or minus 5. This means that some cars could be at 50 psi and others at 60 psi which is a great difference about 20% more from 50 to 60 (this seems to be a large variance and something that should have a much closer tolerance). He feels that an engine running this rich is causing me to lose some good rwhp (around 15). I believe him as my car after the valve job just reached 431 rwhp on the dyno. Again he feels that being between 50-55 psi would definetly boost my rwhp. What are your thoughts? I would like to ask DC to replace this unit if this will help me get to a more repectable rwhp like other cars that have posted their results. It seems that the average is in the mid 440's and that throws me off by about 15 rwhp.

 

[Dyno Dave]

Was it checked at full load/power or at idle? It makes a difference. When was the last time his gauge was calibrated?

 

[kenvw]

I would say that all the equipment is very well kept as this is what he does for a living (make high performance car mods). I believe the reading was done at full load.

 

[Mike Brunton]

Ken,

I would say it would be a tough call to get DC to replace it since it *is* within spec, even if just barely.

Maybe you could try an aftermarket A/F calibration unit to lean it out a little bit??? You could probably get more than 15 even.

 

[Torquemonster]

Mike's right Ken - plus provided the pump is flowing well - the extra pressure could actually be a help later on if you wanted even more power.

In the meantime, the ability to modify the factory A/F ratios would make a big difference - whether via a chip burned for you (cheapest way) or a programmable ECU (which offers the ability to change timing and A/F) - either will enable your car to be tuned over its whole rev range.

It would also be possible to add a high flow regulator into the fuel line and reduce pressure but programming the ECU will give a better result.

Having said all this - your tuning guy should know all this and be able to research the best way to re-map your fuel curve. If the SRT10 ECU is tamper proof and no programming fixes are available for it yet - the only solution may be another fully programmable computer - but that'd be the end of any mechanical warranty - the Competition Coupe runs a MOTEC and they are infinitely adjustable. Frankly I'll be surprised if someone somewhere has not been able to tamper with the factory ECU settings and burn an upgraded chip.

 

[kenvw]

The tuner is going to use a program or chipset to change the ratio flow. Sounds like he knows whats going on. Thanks for the input.