stevieturbo

ID1000's should be fine.

How is your fuel pressure at present ? And what injectors ?

TracyRR

iTrader: (8)

Base fuel pressure is 68 with a 1:1 boost regulator. Currently using the Seimens 80 pound injectors.

stevieturbo

But what is fuel pressure like under load ? Are the pumps coping as they should ?

TracyRR

iTrader: (8)

Oh yes, i hung a mechanical gauge on it while blasting and the deatschwerks pumps are great under load.

TracyRR

iTrader: (8)

Just wanted to update the thread....after doing some more logging, it is better from 5000 rpm's but loses steam around 5800 rpm's. Again, first gear pulls great to 6500 rpm's easily but it is spinning. Second gear and hooked up, it won't pull hard in the upper rpm's. I'm getting frustrated so i called and left a message at TEA (Total Engine Airflow). My plan is to install some powdered metal guides so i can continue running the factory rockers and get his thoughts about my combo. The rockers did make a big difference in the seat of pants and in my fueling requirements above 5000 rpm's but i still have issues approaching 6k and above when hooked up in second gear. It may require lighter valves, more spring pressure or who knows what. I'll update the thread after i speak with TEA. p.s... i did install some D585 truck coils as an inexpensive upgrade with no change at all and just for kicks i installed some larger exh housings that i had (1.0) and all it did was slow down spool (so i switched back to the .68's). Thanks

Remo

Open the exaust. Take the muffler off. I bet the back pressure is holding the ex valve open or floating. Geoff tuned my car 2 weeks ago. I had that problem in the past. Stronger VS and 3in all the way out the rear fixed mine. I doesn't stumble or break up, but u can see a spot on the dyno where in goes flat around 5400 to 5600.

99 C5

LS3 with ported 317 heads
LPE gt2/3 cam
APS TT system with LG turbos
Fast 102
812hp and 833tq x@ 14 psi

Remo

TracyRR

iTrader: (8)

hey remo, That does sound like what mine is doing but i have dual 3.5 exhaust all the way out and i measured my back pressure/boost ratio and it was approx 1.3:1 at around 15ish pounds of boost. I'm thinking i need to take my springs closer to coil bind. The springs are supposed to have a coil bind of 1.085 with a 1.85 installed height (.700 max lift w/.060 to coil bind). I have mine set at 1.835 with only .610 lift (.140 to coil bind) so i don't think i'm close enough to coil bind and it may be making my springs have bad harmonics. That will prob be my next move because it is free, lol. Thanks for the input remo, nice car!!

quik67

Have you tried a lower boost pressure, maybe 10 psi. Maybe 15 psi is still holding the valves open. I have a hard time believing the valve springs are the culprit at 170 seat pressure. I am using a cam with 237/241 duration and .603/.607 lift and run 15 psi to 7000 rpm with absolutely no problems with 135 seat pressure. However I am using 317 heads with stock 2.00 intake valves. Just trying to throw some more ideas at you. Does your afr numbers change drastically at the upper rpm's? I would think unburnt oxygenated fuel would start to read extremely lean if under valve float.

TracyRR

iTrader: (8)

Hey quik, yes, i did lower boost to 10 pounds and it did not make any difference other than slow the car down. Once i changed to stock rockers, i had to throw some more fuel at it above 5k rpm's but once it hits the rpm wall, the afr's are fairly constant. Thanks quik

stevieturbo

Said before, it is not valvetrain. It's either far too rich or there is an ecu/electronic problem. If afr's appear fine during the problem, lean it out to test.

Put a tdc mark on your crank pulley and verify timing is as commanded at all times.

TracyRR

iTrader: (8)

yes, good point, i need to verify timing with a light. It was fat at 10.0's and i leaned it out to 11.0's and no change other than pulling a little stronger. My last motor (few months ago) went to 6500 rpms and it had all the same electronics. It just confuses me that it rpm's well in first while spinning but that is about it. I realize it is under more load while its hooked and in second gear but i just have not figured out why yet... Tomorrow I am going to set the springs to the correct coil bind and i'll update then. I should have stuck this on an engine dyno before i dropped it in... Thanks stevie

slow67

iTrader: (2)

Have you done a crank relearn with the new motor?

TracyRR

iTrader: (8)

Update.... I performed a crank relearn as suggested and I also shimmed the valve springs to the proper height, .065 to coil bind with only minimal improvements. Looks like it gave me another 200ish more rpm. First gear will immediately buzz to 6900 while spinning (but accelerating) and second gear will accelerate close to 5900 rpm. Before my afr was around 11.0 at 5600 rpm's and after the change it went to 13.0!! So shimming the springs did a little but not where it should be IMHO. I think i will throw a little gear in it and be done with it... I currently have a 2.73 gear with 28" tire so i may put a 3.15 in it to help accelerate the car and also keep nice street manners. Hopefully this will also tighter my converter up a bit as well. Thanks for all the help guys, i really appreciate everyone's input!! tracy

Nitroused383

iTrader: (10)

What lifters are you running and how much preload? Sounds like you may be collasping your lifters.

stevieturbo

You made two changes at once. IMO no way in hell did shimming the springs make that difference to AFR's

Check timing.

TracyRR

iTrader: (8)

hey nitroused, running the comp replacements with 1/2 turn on them. I do plan on changing those out to morels pretty soon just to rule that out. Thanks for your help man

No, i seperated the changes, they were not made together. The crank relearn did not change the way the car performed. I will check timing when i get my hands on a timing light. The afr was lean because i tuned the fueling before i started making changes to correct my valvetrain issues. It did not require much fueling where it was having issues because it was not making power there. Once i started to correct things (ie: lighter stock rockers and stronger valve springs), it needed more fuel in the rpm range where it was unstable before the change.

Nitroused383

iTrader: (10)

You may be a good canidate for some short travel lifters.

Johnv

A less aggressive cam lobe could be your answer.

Nitroused383

iTrader: (10)

That is true Johnv, one of the first things I mentioned in this thread. Valvetrain noise at idle will be much quieter also. Comp HUC lobes would be awesome in this setup, and considering there is a sponsor on here doing custom comp grinds for $360 shipped it makes it hard to beat. I have the HUC lobe profiles on a excel spread sheet if you're interested.

TracyRR

iTrader: (8)

Yes, i was looking at those.
If the engine was out, i would do it in a second!! lol. I didn't spec this cam, it came in a short block i purchased but i would certainly do it differently now. Thanks