48 lb/hr (504cc) 12-ohm impedence on 1.9L?

Minami Kotaro · Post by **Minami Kotaro** » Sun Jun 18, 2006 3:36 am

Any first-hand experience with those or larger injectors on a 1.9L engine? This is primarily a street car. I'm a little worried about idle.

chrispel · Post by **chrispel** » Sun Jun 18, 2006 5:52 am

You will be fine. Many saturn 1.9L guys are running 52# injectors without any problems.

keithmac · Post by **keithmac** » Mon Jun 19, 2006 3:19 am

I run 500cc/min on a 1.8 16v with no problems.

Minami Kotaro · Post by **Minami Kotaro** » Thu Jun 22, 2006 5:12 pm

Well, I was planning to put them in with the "new" engine but I went ahead and put them on my current engine.

If anything, they idle better than the 36 lb/hr injectors. Off-idle response is much improved as well. The only tuning I've done is reset my req_fuel (from 9.6 to 6.3) in Constants and in VE Table Tools. This bumped all my VE numbers up an insane amount so I'm sure it's pig rich.

The new injectors are disc-type whereas the old were pintle-type. How much difference would that make?

Bernard Fife · Post by **Bernard Fife** » Thu Jun 22, 2006 5:25 pm

Minami Kotaro,

When you install larger injectors, you should change the req_fuel, but NOT scale the VE table. These two changes counteract each other, so the net effect is to make the entire table richer by the amount your injectors are larger. That is, the fuel pulse widths stay the same, but more fuel flows because the injectors flow more in a given amount of time (in your case 9.6/6.3 = 52% richer).

'Reset req_fuel' is for when you want to keep the same injectors, but change the req_fuel and VE table numbers (while keeping the same fuel amount). You might want to do this if you guessed at your injector flow but later found it was incorrect, for example.

When you go to larger injectors, you also have to scale the cranking pulse widths, accel enrichments, and other 'non-percentage' values by 6.3/9.6 = 65% to keep the same amount of fuel. Values in percentages (VE, warmup enrichment, afterstart enrichment) do not need to be scaled.

Lance.

Minami Kotaro · Post by **Minami Kotaro** » Fri Jun 23, 2006 3:14 am

Thanks, Lance. I was thinking it over at work and figured I only needed to change req_fuel.

As for cranking pulswidts and other enrichments, I don't even use those so it isn't an issue.

jsmcortina · Post by **jsmcortina** » Fri Jun 23, 2006 4:02 am

Minami Kotaro wrote:As for cranking pulswidts and other enrichments, I don't even use those so it isnt' an issue. :D

How do you get it to start if you don't inject fuel during cranking?

James

Minami Kotaro · Post by **Minami Kotaro** » Fri Jun 23, 2006 10:42 am

jsmcortina wrote: How do you get it to start if you don't inject fuel during cranking?

James

Magic.

What I meant by that is, I don't have the cranking table turned on. I just use the "PW at -40 and PW at 160" values in Warmup Wizard. I've got a pretty old version of MegaTune.

I don't use any AE, WUE, or ASE.