Does anyone know what the minimum operating pressure is for both GM and SVO 19 lb/hr injectors? Thanks...

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Black 88 GTA L98
261 RWHP, 345 RWTQ
ZZ4 bottom end, Edelbrock 6085 heads, LT4 HOT cam, GMPP 1.6 RR's, ported stock TPI, SLP 1 3/4" headers, no cat, Dynomax cat-back, Stock PROM
E.T.F.A Member #11

 

Most injectors are rated at 43.5 PSI. That is where the 19lb/hr, 21 lb/hr, etc. flow ratings are established.

Ford injectors are strange. Their systems run at 36 PSI, so you need to be careful to know what PSI they are rated at.

As to a minimum pressure, I am not sure. At some point the spray pattern will deteriorate, but that is dependant on the type of injector (pintle, disk, etc.). Pintle would be the most concerned with pressure for flow pattern. Little flow will mean a pattern less than optimal. Disk injectors will hold their shape even at low pressure.

Your questions is a bit strange. What is the context around it?

Mark.

 

The spray pattern of pintle type injectors begins to go down hill below 40 PSI and takes a nose dive at around 30 PSI

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Tracy /AKA IROCKZ4me
'86 IROC-Z Camaro

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• modified SLP runners
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• SLP cat-back
• Paxton supercharger
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Scott, I assume that the reason for your question must be because you have a rich condition and want to lower your fuel pressure to cure it.

If so, the most effective way is through the eprom. I have found that even with an adjustable fuel pressure regulator, some of them will only let you reduce it so much. Also, the effects of fuel pressure is most noticeable at higher MAP/load (low vacuum) conditions and less effective at low MAP/load (high vacuum). That is why adjusting your fuel pressure is not the same as installing different sized injectors.

Cranking up the fuel pressure on a stock 22# injector will make it behave like a 24-26# injector (depend on fuel pressure) at the higher load (low vacuum) situations like WOT. But at lower load (high vacuum) situations like idle and light part throttle, it will still behave close to a stock injector.

Conversely, reducing fuel pressure will make a 22# behave like a 19# at WOT, but still behave like a 22# at idle/light part throttle.

That is why when you replace the stock 22# injectors with SVO 24# injectors, you really need to adjust for it in the eprom, not with fuel pressure to be totally effective.

 

Sorry guys, I should have explained this a little bit better.

I'm not asking this question regarding my car, but rather my Senior engineering project. We are building a car to compete in the Formula SAE competition. We are using a Honda CBR F3 600 cc engine, and we are building a custom fuel injection system. According to the calculations I have made, the ideal injector size for this engine is 12 lb/hr. However, I have not been able to find and injectors rated at less than 19 lb/hr. So I was wondering what the minimum pressure they would operate at was so I could recalculate their flow at that pressure. Or if any of you know where I could find smaller injectors I would appreciate any leads, thanks.

 

Look at shortening the pulse width. There are limits, but it may help. Why not look at some of those injectors on those foreign cars or a small 4 cylinder with MPFI?

Among the people here, we all have "American sized" injectors....big, strong, and sturdy.