#46004, "How will a rebuilt 420a react to detonation?" Apr-01-03 03:55 PM by etx
I'm going to be installing my built motor this weekend. Its got JE's 25 over at 8:1, eagle rods, p&p head, 1mm oversized valves with six angle / 3way valve job, new lifters, and a five layer mls headgasket. When tuning the fuel system if i see any detonation how will it react? I know the crank in this thing is supposed to be solid. But what kind of problems could i run into with knock on this bad boy? I can't wait to get my baby back on the road! TIA!
____________________________________________________ four nails four corners four riders and four horses
#46007, "RE: How will a rebuilt 420a react to detonation?" In response to Reply # 0
well dave_fl melted like 3 JE's a while ago. they're not indestructible, although there is a larger margin for error than the stock ones. just try to tune it as if there's no room for screw up and you'll be fine
#46009, "RE: How will a rebuilt 420a react to detonation?" In response to Reply # 1
Yeah it will take quite a bit of detonation to crack the forged pistons. Its more likely for them to melt rather than crack like the stockers. Forged pistons can take some good abuse, although prolonged detonation on ANY piston will damage it in the long run.
13.5 @108 MPH-2.2 60ft(stupid FWD!) S16G @ 18 PSI/FMIC/Running on MegaSquirt II (Now with sequential fuel injection) My webpage: http://eclipsed4evr.home.comcast.net -1998 Mitsubishi Eclipse RS-T- "Toy" -1992 Plymouth Laser Turbo AWD(SOLD) -2000 Honda CR-V(daily)
#46015, "RE: How will a rebuilt 420a react to detonation?" In response to Reply # 3
I was getting detonation but the reason why my pistons melted was because of the headgasket going out and the temps just got way too high. I actually saw my temp gauge zoom into the red. My engine was knocking like crazy though at 15psi. I really didnt knwo what detonation was back then but now I do and this time I will be using the msd to retard timing. Dont run much over 9-10 psi unless you have the msd.
#46016, "RE: How will a rebuilt 420a react to detonation?" In response to Reply # 4
"Dont run much over 9-10 psi unless you have the msd."
dont run over 9-10 psi's unless you know how to tune... if you know how to tune you can run up to 16-20psi's without a msd.. people on this board are running 15 psi's with no msd. the msd is a very nice device if you have the extra money to dump into it. they do have a high failure rate though, armond went through a couple of pistons due to his device. check this guys setup.. http://www.armond30.com/adp/004.html . he sees 22psi's with timing advances barely tipping 20 anything over 22psi's its been theroized that timing would have to pulled, via a msd or crane unit or any timing retard module. so yes, you can go well into the teens without a msd.
#46020, "RE: How will a rebuilt 420a react to detonation?" In response to Reply # 5
>>>Dont run much over 9-10 psi unless you have the msd.<<<
That may be true if you do a large correction with an AFC. At WOT you will see 17-22 degrees advance whether you are at 5psi, 10psi, 15psi, 20psi...our ECU does NOT know how much boost you are running so there is no magic boost number that you need to retard timing. Granted 20 degrees advance may be too much timing at 25psi of boost. I don't know I've never tried. But the point is you won't get any more advance at 25psi than you will at 10psi.
#46024, "RE: How will a rebuilt 420a react to detonation?" In response to Reply # 6
i thought i would blow in 2 months, its been a year and a half and i have learned alot about my car and 'tuning' dont know everything, but enough to get me by. not stupid enough to lean my afc out all the way to fu*k my timing up to cause me to fuc* my internals up so soon. i just want to build my spare motor so if i blow i blow, Michael 99gs HRC Stage 2 @12psi Stage 3 process begins gathering parts for rebuild 2GNT Member #32 http://www.dreamwater.net/purplebeast
#46036, "RE: How will a rebuilt 420a react to detonation?" In response to Reply # 7
Yeah thats what i did. I plan on running 12 psi daily on this guy. What do you guys recommend I do to properly tune it. I would like to run 16 psi at the track.. but thats a bit down the road.
____________________________________________________ four nails four corners four riders and four horses
#46056, "RE: How will a rebuilt 420a react to detonation?" In response to Reply # 8
Well let me add that I have 440cc injectors and my safc is leaned out some. That is a big factor. So let me change what i said to dont run over 9 psi if you have large injectors and safc unless you have a msd to retard timing.
#46074, "RE: How will a rebuilt 420a react to detonation?" In response to Reply # 9
check my link up top, armonds 004 project is running 440s safc and 16-20 psi's, no retarding module and its still running strong, he doesnt get dangerously advanced timing till he hits 22psi's. Its all in the tuning.
#46119, "RE: How will a rebuilt 420a react to detonation?" In response to Reply # 10
On Mark's car they idle it at a very low psi. That way they can get away with very minimal tuning on the AFC. I don't think the Cartech Dave has can do that. (I'm talking real low idle pressure, like 15psi I think) Correct me if I'm wrong.
#46137, "RE: How will a rebuilt 420a react to detonation?" In response to Reply # 13
My cartech POS wont let me turn the fuel presure down so I have to lean it out on the safc. I realy hate my fpr but it will do untill I get the sfmu. If I could drop my fuel presure down quite a bit then I could richen up the safc and I would be fine. I will be ordering the sfmu very soon if I dont find a good deal on one used.
#46155, "RE: How will a rebuilt 420a react to detonation?" In response to Reply # 13
>hrmm, i have never heard of this. Hey XtremeRS what do you >think?? I want to run 12 psi daily, do i need this stuff?
All you need is enough fuel to run 12 psi daily. You dont need any timing retard or any other igntion devices to run 12 psi. You can run that boost on the SFMU, 30lb injects, and a good fuel pump. Fuel pressures at 12 psi on those injects will be close to 95-100 psi, so be sure your fuel system and pump is capable.
13.5 @108 MPH-2.2 60ft(stupid FWD!) S16G @ 18 PSI/FMIC/Running on MegaSquirt II (Now with sequential fuel injection) My webpage: http://eclipsed4evr.home.comcast.net -1998 Mitsubishi Eclipse RS-T- "Toy" -1992 Plymouth Laser Turbo AWD(SOLD) -2000 Honda CR-V(daily)
#46235, "RE: How will a rebuilt 420a react to detonation?" In response to Reply # 0
detonation will cause you to break tips off of spark plugs, beat ugly dents around yoru pistons, and slap them against the cylinder walls, greatign really ugly dings and scratches in your cylinder walls and makign yoru piston look like a tiny aluminum waffle house waffle (at least the top part anyway). to make a long story short, detonaton will f#$k you up.
A.D.P. "...If you do too much, people become dependant. If you do to little, people loose hope. If you do it right, people won't be sure you've done anything at all." bring it on...........
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