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#1
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408 Stroker Detonation - Help!
I am new to to Mopar Chat and signed up so that I could get some feedback as I am not getting it from help from my builder and or custom engine tuner.
A couple of weeks ago my builder completed my 408 stroker for my 1997 dodge ram 2500 4x4. The following performance mods were included in the build (Edelbrock 202/160 alum heads, Comp Cam 480 lift,212/218 duration, 114 separation, Probe Forged dishtop pistons, Accel 24lb injectors, Pacesetter L/T Headers, Dual Cats, New Forged Rods). The throttle body and intake were left stock at the recommendation of my builder who said I only need to replace those if we were going after a higher RPM engine which we were not, instead low end and mid range torque and HP. When I picked the truck up it seemed to run good but was I was really dissapointed in the power as it did not seem much better than when the truck was new which was 235 flywheel hp and 330 torque. I had the truck put on a Dynojet before the rebuilld which produced 170hp and 250 torque at the rear wheels. I had it dynoed again after the rebuild which produced 221hp and 298 torque at the rear wheels for an engine that was supposed to have 365 hp and 560 torque at the flywheel. I was informed that I needed to flash my stock PCM which would open the capabilities of the engine. I went to KRC performance who provided an SCT Xcal2 with a couple of different custom tunes which changed timing as well as A/F mixture changes and tranny shiftpoint changes. The timing for the tunes were 32 degrees, 30 degrees, 28 degrees and the latest at 26 degrees but they all cause pinging/detonation at WOT, even with 93 octane fule and an octance booster. I also had the truck dynoed again with the 26 degree tune and the results were less HP and Torque than the stock tune and the new tune showed it to be lean at the lowend and way to rich and the high end. Marty from KRC said that I needed to change to colder plugs and a 180 degree thermostat which I did, but to no avail as it pings on any tune other than the stock tune. KRC has provided me with NO MORE tunes and they are telling me that something is wrong with my Motor. I am going back to my builder but I am not sure what things to be concerned with about the motor. Does anyone have any suggestions on what the problems could be and what should be having my builder check out? When I run on the "stock" program I do not receive the pinging, but also I am not getting the HP and Torque that I should be getting. |
#2
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Sounds like...
Your throttle body is on the lean side for what you have built. The stock ECU is also suspect, both for advance and fuel calibration. You really need to find a shop that will put an air/fuel probe on your truck, and verify what I suspect is the problem.
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#3
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Thank you for the feedback. Before the build began I asked my builder if we needed to upgrade to a 55mm dual TB but he said the stock would work just fine as the goal was low end torque for towing and the RPM levels remaining stock. At the recommendation of KRC I am installing the M1 intake next week.
As far the PCM are you saying that the stock PCM will not accomodate the 32 degree timing & a/f settings that KRC is providing in the custom tune program? |
#4
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Might check for vacuum leaks......
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#5
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All of the stock throttle bodys are lean!!! None inject any fuel at all. They are air valves, that is all.
Fuel comes from the injectors. Please educate me-a student- to what you mean. |
#6
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Quote:
Maybe a Quench problem with the dish pistons... 365hp Combo... ???? Get the build sheet / specs Who told you that. The engine shop or the Tuner guy's ???? Did KRC run this on the dyno and check out the fuel curve and timing???? If the motor is ok...Think your going to need a 55mm throttlebody / Custom PMC |
#7
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At first I was thinking too much compression or no quench, which it still might be. Did you run the combo through a comp. ratio calculator ?
You might also want to check that the injectors aren't too small and the duty cycle isn't running 90%+++. |
#8
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At first I was thinking too much compression or no quench, which it still might be. Did you run the combo through a comp. ratio calculator ?
You might also want to check that the injectors aren't too small and the duty cycle isn't running 90%+++. |
#9
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At first I was thinking too much compression or no quench, which it still might be. Did you run the combo through a comp. ratio calculator ?
You might also want to check that the injectors aren't too small and the duty cycle isn't running 90%+++. |
#10
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You need to find shop that can map out your fuel supply. Fuel supply (bigger fuel injectors), injector timing, and injector pulse (how long they spray) will have a huge impact on how your now modified engine runs.
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