After a painful death, my motor is alive again, better,stronger, faster
05-01-2006, 01:27 AM
#1
After a painful death, my motor is alive again, better,stronger, faster It all started back in October when I decided to convert my car to auto after refusing to pay over $1000 for a clutch. Ordered up a nice th400 tranny from rossler. Got everything installed and ready to go, double checked everything... everything but the oil level.... 
Ended the glorious 1 hour enjoyment of my car with a slight ticking coming from the bottom end. Oil level was almost 2 qts low (motor had been consuming 1qt every 1000, 75k mile stocker). Low oil light is broken and the car had been down for about 4 weeks while waiting for tranny and parts since I sold the 6spd.
Turns out the low oil was just the straw that broke the camels back. When the pan was pulled off the stock motor there was a handful (literally) of bearing material in the pan. A handful of bearing material doesn't come from a few minutes of run time with a slight tick. Looks like I was the victim of rod bolt stretch is my best guess. I was regularly shifting it at 6500 with the limiter set at 6700.
Not only did i have several messed up rod bearings, it had also turned out that 3 of my pistons decied to bump uglies with the valves. Two of them looked like they had been bent quite a while ago too, which could explain why I had trouble making more than 13 psi. Turns out that 918's + 15psi of boost for 12,000 or so miles on a 224/224 cam just doesn't work as well as I had hoped.
Chapter IV "A New Hope"
During all my time playing around with upto 16psi on my stock motor I had decided it was wise of me to start amassing parts for a 408 build. I scrapped the 408 plans when I found out a friend had some nice pistons from a failed 370 APE motor with less than 1000 miles on them for $200. My new motor has the following parts.
Iron 6.0 block
Diamond 4.030 pistons -15cc
Eagle 6.125 SBC rods
stock crank
6.0 heads
6.0 .05x MLS gaskets
Z06 cam
Total seal rings
Got to drive it around a little last night, found a few bugs and my buddy who built and installed the motor for me straightened them out.
Took the car out for a spin today to get 50 or so miles on it to make sure everything was good to go (no leaks, etc). I also had to burn off 1/2 a tank of 6 month old 91 octane. Got down to 1/4 tank and put 4 gallons of 100 in it for some testing.
On the way home from my f-body club meeting decided to lean on it a bit on the high way to see if it would knock at all on the scanner. Boost hit's hard and went immediately to 10psi and the smile on my face hit even harder.
I can't wait to get the rest of the tune sorted out tomorrow and hook the boost controller back up. Gotta keep the boost limited to 12 psi for now due to my lack of a good fuel system (just a single walbro, duals with rails and AFPR coming soon).
So the lesson learned from this, boost didn't kill my stock motor, neither did detonation. RPMs did my stock bottom end in. I was going to go for 750-800 rwhp on the stock motor. Best I ever got was 625 rwhp at 14psi spinning the tires on the rollers on a motor that most likely had bent valves.
BTW, when looking at the pistons from my stock motor they look perfect (except the 3 with the custom valve reliefs). No melting anywhere on them, no cracked top ringland, no pitting, no signs of detonation. The valves looked good too, sans the piston loving ones. The last 2000 miles on the motor were all at 10-11psi, the lowest my wastegate would go, 91 octane and a little bit of water/meth added for safety, but not really neccessary.
Cliffs, Dead motor, New Motor, Happy.
Ended the glorious 1 hour enjoyment of my car with a slight ticking coming from the bottom end. Oil level was almost 2 qts low (motor had been consuming 1qt every 1000, 75k mile stocker). Low oil light is broken and the car had been down for about 4 weeks while waiting for tranny and parts since I sold the 6spd.Turns out the low oil was just the straw that broke the camels back. When the pan was pulled off the stock motor there was a handful (literally) of bearing material in the pan. A handful of bearing material doesn't come from a few minutes of run time with a slight tick. Looks like I was the victim of rod bolt stretch is my best guess. I was regularly shifting it at 6500 with the limiter set at 6700.
Not only did i have several messed up rod bearings, it had also turned out that 3 of my pistons decied to bump uglies with the valves. Two of them looked like they had been bent quite a while ago too, which could explain why I had trouble making more than 13 psi. Turns out that 918's + 15psi of boost for 12,000 or so miles on a 224/224 cam just doesn't work as well as I had hoped.
Chapter IV "A New Hope"
During all my time playing around with upto 16psi on my stock motor I had decided it was wise of me to start amassing parts for a 408 build. I scrapped the 408 plans when I found out a friend had some nice pistons from a failed 370 APE motor with less than 1000 miles on them for $200. My new motor has the following parts.
Iron 6.0 block
Diamond 4.030 pistons -15cc
Eagle 6.125 SBC rods
stock crank
6.0 heads
6.0 .05x MLS gaskets
Z06 cam
Total seal rings
Got to drive it around a little last night, found a few bugs and my buddy who built and installed the motor for me straightened them out.
Took the car out for a spin today to get 50 or so miles on it to make sure everything was good to go (no leaks, etc). I also had to burn off 1/2 a tank of 6 month old 91 octane. Got down to 1/4 tank and put 4 gallons of 100 in it for some testing.
On the way home from my f-body club meeting decided to lean on it a bit on the high way to see if it would knock at all on the scanner. Boost hit's hard and went immediately to 10psi and the smile on my face hit even harder.
I can't wait to get the rest of the tune sorted out tomorrow and hook the boost controller back up. Gotta keep the boost limited to 12 psi for now due to my lack of a good fuel system (just a single walbro, duals with rails and AFPR coming soon).
So the lesson learned from this, boost didn't kill my stock motor, neither did detonation. RPMs did my stock bottom end in. I was going to go for 750-800 rwhp on the stock motor. Best I ever got was 625 rwhp at 14psi spinning the tires on the rollers on a motor that most likely had bent valves.
BTW, when looking at the pistons from my stock motor they look perfect (except the 3 with the custom valve reliefs). No melting anywhere on them, no cracked top ringland, no pitting, no signs of detonation. The valves looked good too, sans the piston loving ones. The last 2000 miles on the motor were all at 10-11psi, the lowest my wastegate would go, 91 octane and a little bit of water/meth added for safety, but not really neccessary.
Cliffs, Dead motor, New Motor, Happy.
05-01-2006, 12:59 PM
#7
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Hey Jeremy glad you got it running!! It broke my heart to see it up on the lift at Jon's house. I do want to ride in it as will be having Jon build my car too later on if you can someday give me a ride in it! Sorry missed the meeting but was working.
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05-01-2006, 03:35 PM
#9
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i love the write up!! good luck with the new motor!! im hoping to get a 6.0 motor as well did you bor and hone the block out to make it a 408? and those are special turbo pistonS??
how much did you spend on the forged motor!?total?
how much did you spend on the forged motor!?total?
05-01-2006, 04:42 PM
#10
TondSS, the motor is a 370, I gave up on the 408 when I snatched up some pistons for a 370 for $200. I also wasn't that big of a fan that the wrist pin was going to be in the oil ring and a plug would be needed. Something I've never seen mentioned on here before and that I only came to realize after calculating compression heights and holding a 370 piston in my hands.
