#74991, "Seriously thinking about rebuildling...fuel question"
I am in need of replacing my HG because it blew a couple weeks ago, and since I am going to be ripping everything out of my engine bay, I was thinking why the heck shouldn't I use this opportunity to rebuild the bottom end altogether? I mean it's all right there.
So if I were to do this, I would definately get the Howell Automotive kit with the lower compression. I would also purchase a digital boost controller, SPEC stage 3 clutch, SFMU, and 390cc injectors(FPR gauge too).
My question concerns the fuel management setup. I for some reason have always half-understood fuel setups:
Will the SFMU with the larger disk, and just bleed out the excess pressure, be sufficient enough to regulate fuel altogether? Or does the bleed valve only regulate idle conditions? What combination of disk/spring/bleed valve will optimally work with a 15psi daily potential setup?
I know the 390cc injectors will be sufficient enough.
bobin' and weavin' in traffic. No other place i'd rather be .
#74992, "RE: Seriously thinking about rebuildling...fuel question" In response to Reply # 0
Dont ya think 390cc injectors would be pushin it for 15 psi daily? aren't most of the guys here runnin 440's and for the sfmu you can adjust more than just the idle pressure
1.) The main adjusting screw sets the basic static fuel pressure level of the unit. By adjusting the main screw any initial pressure can be set. 2.) The calibration ring and disc are used to set the slope of the fuel pressure increase with increasing boost pressure. Four different diameter rings and discs are included with the SFMU. 3.) The vacuum screw acts like a vacuum regulator. If it is set to give, for example, 5 in hg gauge, the upper chamber of the SFMU will only see 5 in hg even though the engine manifold pressure may drop to 18 in hg at idle. The result of this is the fuel pressure remains constant from idle vacuum up to 5 in hg then the pressure will start to increase. 4.) The optional bleed screw does two things. First, it will lower the slope of the curve set by the calibration ring. So, it can be used to "fine tune" the pressure vs. boost curve. Second, it acts as a damper to "soften" the transitions in the curve. 5.) The boost screw acts in a similar manner as the vacuum screw in that it performs like a pressure regulator. It can be set to limit the maximum fuel pressure. If the screw is set all the way in it will not regulate and the curve will continue to rise as boost increases. If the screw is set to relieve at, say, 10 psig then once that manifold pressure is reached any manifold pressure above that will not increase the fuel pressure. More here.
^ vortech website.
Steve-o Top secret.
Originally posted by FlyinEsi I guess I'll just have to live with a 500+ hp AWD 4-banger.
#74995, "RE: Seriously thinking about rebuildling...fuel question" In response to Reply # 1
alright, then I suppose the appropriate question would be what injectors would be necessary to run 15 psi daily and 18-20psi at the track? What SFMU setup would be necessary?
bobin' and weavin' in traffic. No other place i'd rather be .
#75022, "RE: Seriously thinking about rebuildling...fuel question" In response to Reply # 2
440cc(42lb) injectors would more than likely be good.
and to quote ner947
"I second that.
For 415-440 cc/min injectors the proven setup is to use the 2.72" disk, dark spring, idle pressure set around 15-20 psi, static pressure set around 30-35 psi. All of this, of course, depends on the alingment of the planets. Play around with different pressures and see what works best on your car."
Steve-o Top secret.
Originally posted by FlyinEsi I guess I'll just have to live with a 500+ hp AWD 4-banger.
#75028, "RE: Seriously thinking about rebuildling...fuel question" In response to Reply # 3
Well, I think I am 85% sure that I am going to get the rebuild kit. But because of monetary issues, I cant upgrade all the way so I can up the boost, at least not for this summer. I will remain at 6 psi until next working season when class is out and I can get all the other little goodies, and then the fun will truly begin .
This is my list: 1) Howell Automotive bottom end rebuild kit 8.6 compression 2) bottom end/Head gasket set 3) ARP head studs
Let me know if I should get an other things for the setup I am going for this summer.
On another issue, I am a little confused about the differences between the long rod kit and the regular kit. Any inputs?
bobin' and weavin' in traffic. No other place i'd rather be .
#75042, "RE: Seriously thinking about rebuildling...fuel question" In response to Reply # 6
Originally posted by techboy Be warned ... it's not always all that fun. I did a rebuild and my car hasn't the light of day for 9 months. Too many unforseen obstalces. Good luck.
Could you maybe be a little more specific? What kind of obstacles did you encounter, and are they common enough that I should be worried?
bobin' and weavin' in traffic. No other place i'd rather be .
Excellent . So it looks like the long rod in general sounds like a better deal, as it increases bottom end torque, decreases the overall stress, and allows for a better explosion in the chamber. Thanks for the link.
bobin' and weavin' in traffic. No other place i'd rather be .
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