If you exceed its capacity it will, that's by design. Some of the vettes with dualmass flywheels have this function also. Not all dual mass flywheels have this built in fuse.
Making progress towards getting the engine put back in the car. After addressing the camshaft I found that my 112 degree intake centerline was actually occuring at 92 degrees with the cam fully advanced so no doubt that's killing a good bit of power. I used my extra module to determine the thickness of the spacer I would need as seen on the engine, then I carefully removed the back side screws from the sprung module that would be used, carefully replacing them with drill bits to keep the forward hub that would normally be on the front of the module from releasing the recoil load which would be very difficult to restore if you let it unwind. I also placed about a .040" thick piece aluminum in front of the phaser to partially retard it from full advance to move it a little closer toward proper alignment for a little better baseline performance than what was present previously.
The stock cam would probably perform much better fully advanced than my reground cam. Interestingly two other 3900 swappers were not able to start their engines with the cam fully retarded. I could, however, their horsepower levels were about the same as mine if not a little more naturally aspirated and I'm running 7 psi, not sure what their torque levels were but that goes to show you how important camshaft position and grind is. My reground camshaft is probably more sensitive to position as a result.
On closer inspection I also found that 5 out of the 6 exhaust ports had a leak at the flange so that certainly cost power. I found several potential problems during the tear down, coolant seapage at the upper coolant crossover between the heads (reused gaskets without RTV), and a leaking radiator upon removal for replacement with an HD 3 row aluminum rad. I'll have to reinstall the turbo oil drain a little lower in the pan side due to the turbos level which is more unscheduled work along with the blown brake caliper I discovered and the two brake hoses I ruined by forgetting to disconnect them.
The end result will be a lot cleaner and spacey, I would never trade this exhaust configuration to go back to headers.
Last edited by Joseph Upson; 05-11-2010 at 12:30 AM.
Very interesting Joseph. Thanks for taking the time to measure and post the numbers. The measurement taken on the CMM was 17.88 degrees max advance which is just over 2 degrees from the installed numbers. Perhaps the phaser wasn't at it's full limit when the CMM measurement was taken or there is some stack up error from the manufacturing process. That is the reason they make adjustable timing chain sets.
The turbo setup on the stock manifold looks great, like it was made to be mounted there from the factory. It's a clean setup that should be very durable.
Any timeline on when you will have it running again? As always, I am anxious to see your progress and results.
On a side note, the three M6 screws that attach the phaser to the cam seem a little on the small side. Hopefully they don't become an issue when people start putting big cams in these engines. Of course, I was never a fan of the single bolt setup on the earlier engines. The old three M8 bolt setup seemed quite reliable.
Very interesting Joseph. Thanks for taking the time to measure and post the numbers. The measurement taken on the CMM was 17.88 degrees max advance which is just over 2 degrees from the installed numbers. Perhaps the phaser wasn't at it's full limit when the CMM measurement was taken or there is some stack up error from the manufacturing process. That is the reason they make adjustable timing chain sets.
The turbo setup on the stock manifold looks great, like it was made to be mounted there from the factory. It's a clean setup that should be very durable.
Any timeline on when you will have it running again? As always, I am anxious to see your progress and results.
On a side note, the three M6 screws that attach the phaser to the cam seem a little on the small side. Hopefully they don't become an issue when people start putting big cams in these engines. Of course, I was never a fan of the single bolt setup on the earlier engines. The old three M8 bolt setup seemed quite reliable.
I'm hoping to have it running Thursday, I'm in the process of mounting it on the cradle this Wed morning but as usual there are little odds and ends that take extra time. I need to make a coolant return crossover pipe in addition to completing the exhaust so I might not get the engine back in the car until Thursday. As for the cam bolts I would hope the alignment pin offers a good bit of reinforcement to make shearing an unlikelyhood.
Time caught me again and I wound up having to leave a day ahead of schedule so I missed getting the car reassembled to the point of being able to at least hear how the engine sounds with the new exhaust and single turbo but I'm very close to that point at least. I added a bellows for the wastegate so that there is no difficulty with attaching it to the flanges. The exhaust is 3" into dual 2.25". It's a lot cleaner and roomy in the engine compartment and I now have plenty of room for the electric cruise control and water/meth injection unit.
The horsepower and torque numbers should be higher, I forgot to add an additional 200 or so pounds to the vehicle weight to account for me and the fuel when programming the GTech, not sure how much it would increase by. I entered the 2710 lb vehicle wt from my registration. I did a little reverse estimation with my turbofast program and came up with a wt corrected 217 hp, not much more. I couldn't estimate the torque. I'm very pleased with the reconstruction results and expect the performance to improve considerably at the same boost level. The main spark table is conservative in the boost range and I'm running on low octane fuel 88 octane, so there is plenty of room for performance improvement and I expect it once the engine is tuned properly. Hope I'm able to get back to it shortly to finish and test.
Last edited by Joseph Upson; 05-15-2010 at 05:42 PM.
i look forward to referencing it if/when i ever get the 3900 Turbo/F40 for the Monte...
1995 Monte Carlo LS 3100, 4T60E, OBD1 Conversion...for now, future plans include a 3900, T04E-46 (Knock-Off) turbo (For the 3100, ~T61 for the 3900), and a F40.
OBD1.5 to OBD1 Conversion harnesses for sale, click THIS link or PM me for more information.
Need a wiring diagram for any GM car or truck from 82-06(and 07-08 cars)? PM me!
Thanks, I'm just realizing how much power is tied up in this engine with the numbers it posted at just over 4000 rpm. Although desktop dyno is grossly inaccurate in my scenario beyond 4000 rpm regarding the curve it generates with the cam fully advanced and fully retarded, it is not too far off when you take into account the GTech measures net performance and Desktop crankshaft performance, 233 hp 306 lb/ft @ 4000 rpm. Horsepower wise that would be right in order with my corrected 217 hp net. The torque was always on the high side in Desktop however, I can only enter 15 degrees advance max and not the full 20 degrees the cam was actually advanced. Hopefully the cam angle correction will move the rpm power peaks up near the 6000 rpm range where they belong.
you couold advance all of the cam specs 5* so that DD will read correctly... you'll have to remember that the center position is 5* retarded though.
1995 Monte Carlo LS 3100, 4T60E, OBD1 Conversion...for now, future plans include a 3900, T04E-46 (Knock-Off) turbo (For the 3100, ~T61 for the 3900), and a F40.
OBD1.5 to OBD1 Conversion harnesses for sale, click THIS link or PM me for more information.
Need a wiring diagram for any GM car or truck from 82-06(and 07-08 cars)? PM me!
Pre turbo water/meth injection nozzle in place.
Rotating assembly is balanced. Total weight loss ~ 1.75 lbs
Modified new pressure plate. Stock fiero PP ~1650 lb clamp pressure. This plate stock, 1957 lbs. modified to 2357 lbs. The plates left to right; 4 speed muncie new and old and Getrag. Notice the additional strap in the new plate for added strength. Compliments of Tampa Bay Clutch.
Modified 3.4L F-body flywheel modified and balanced to work with the F40 6 speed trans. Should cut rotating mass by about 10 lbs. maybe more.
Pistons and rods ready for install. Rings were file to fit and rods were on the tight side so the bushed end needed honing. I'm starting the build about 3 days late because of that and other last minute discoveries.
The current engine is still in the car and successfully ran under Code59. The T4 doesn't seem to howl as much as I thought it would with open exhaust but I'm listening from inside the car. The car is definately faster than it was with the twins, the cam is still advanced although about 4 degrees less than before so the test with proper install will have to wait for the forged motor. Otherwise it spins the tires fairly easy on take off without dropping the clutch or reving the engine.
I'll be picking up the rod bearings shortly and plastigaging which will be a pain because the rods have alignment sleeves and the caps will not separate without a fight so I'll have to measure the top side of the pin and use a rubber mallet on the bolts to separate.
Hope to have pics of the pistons in the bore by tomorrow.
Static compression: ~11.7:1, boost, we'll have to see, I have a 4 psi spring to swap out the 7 psi for to start with.
Originally Posted by CNCguy
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