Injectors Vs Fuel Pressure

[Roadknee]

Roadknee

its really quite a dog from 3500 up, probably caused by my stock intake. Anything past 4k and feels like you're pulling a parachute lol. Doesn't help with tall tires, 3:42 gears and crappy ratios in the Getrag 5 speed. Have the wideband fitted, great tool for tuning, specially AE stuff.

That is surprising. The ramjet 350 with that cam is rated 350 HP at 5200, although it does use 1.6 rockers. The HT383 peaks at 4600 rpm with that cam using a 4bbl carb. Both engines run vortec heads. I would have thought even flowing through the stock TBI your engine would make around 300 hp at 5,000 rpm. I have a vortec 350 in my shop now I'm building up for my 1995 K1500. I was considering the Ramjet cam, but your experience makes me think perhaps something like Barry is running might be better. Could you remind me what injectors you're running? Also, what's your injector duty cycle at 5,100 rpm WOT? Thanks.

[brian617]

That is surprising. The ramjet 350 with that cam is rated 350 HP at 5200, although it does use 1.6 rockers. The HT383 peaks at 4600 rpm with that cam using a 4bbl carb. Both engines run vortec heads. I would have thought even flowing through the stock TBI your engine would make around 300 hp at 5,000 rpm. I have a vortec 350 in my shop now I'm building up for my 1995 K1500. I was considering the Ramjet cam, but your experience makes me think perhaps something like Barry is running might be better. Could you remind me what injectors you're running? Also, what's your injector duty cycle at 5,100 rpm WOT? Thanks.

I doubt its the cams fault, 1.6 rockers and a better intake would probably be the key. I'm running 305 injectors @ 22psi for roughly 73pph. Last IDC% I can remember recording was around 75% WOT which makes me think I'm only making around 250-275hp.

[Fast355]

I doubt its the cams fault, 1.6 rockers and a better intake would probably be the key. I'm running 305 injectors @ 22psi for roughly 73pph. Last IDC% I can remember recording was around 75% WOT which makes me think I'm only making around 250-275hp.

The 395 marine cam is barely bigger than a stock L31 cam. Stock L31 witha few bolt ons and headers with a good tune is around 280-300 hp. The LT1 cammed L31 in the 99 Suburban is making roughly 350-375 hp worth of fuel disappear. Running 8 x 23.9 lb/hr spider injectors at 92-93% duty cycle at 5,400.

[Roadknee]

The 395 marine cam is barely bigger than a stock L31 cam. Stock L31 witha few bolt ons and headers with a good tune is around 280-300 hp.

Is that 280-300 HP with TBI or Vortec MPFI?

[Fast355]

Is that 280-300 HP with TBI or Vortec MPFI?

With either really...At that power level neither really restricts anything if tuned properly. The vortec CSFI and dual plane TBI intake both fall off sharply around 5,500.

[BLG355]

I am running stock 5.7 injectors at 22psi, so about 80-82lb. I set it up to shift a little higher, 5600. it doesn't really fall off, but it definitely is struggling a little. The cam is only good to 5200 I think. the KPA is around 88 at 5600rpm @ WOT. I did the lid flip before and it made zero difference, I guess it just needs more air if I decide to try 5500 rpm shift points.

IDC.JPG

[BLG355]

Here is the stuff I said I was going to post the other day and didn't. if anyone wants to take a look and give me some feed back I'd appreciate it. I didn't smooth the fuel tables as I should because it changes them right back pretty much every time I run it, so they I just sort of let them a little rough. The truck runs good, after about 1/4 to 1/2 throttle over 2500 rpm it feels a little weird like something is a tad off, but it seems to smooth out then. the fuel table is probably a mess and needs a makeover. But it idles good cold and drivability is good. If I tucked the ECM back in the dash and didn't tell someone it was a work in process, they probably wouldn't even notice by driving it. Since I used brian617 AE settings and they smoothed out al that stuff, I have been trying so many different things just to see what it does when I change it...I should take a break for a few days and just drive around with it instead of changing so much...but it is so much fun!