lz9 3900 V6 buildup

[eHoward]

Sorry to read that shaun. that sucks.

I actually just did a starter change a few weeks ago because it was starting to strip the gears but that looks pretty bad!

[CaptainHindsight]

Ring gear not concentric with the flywheel? Ring gear out of round? Not enough clearance between starter gear and ring gear? How does the starter gear look now? Any play in the starter gear?

[ericjon262]

backfire while starting?

[pmbrunelle]

backfire while starting?

Ignition timing during cranking can have an effect on this... also ignition timing during cranking is not necessarily super-accurate, because the speed of the crankshaft is not constant.

On my own car, I changed the commanded cranking timing from 10° BTDC to 5° BTDC, and that reduced the feeling of the engine hitting a wall when it fired.

[Shaun41178(2)]

Replaced the flywheel with a standard steel autozone one. Also replaced the starter as it was bad.

I think the starter went bad which broke the teeth on the flywheel. I put it all back togethor with the same starter and it was still making twrrible noises when trying to start. Swapped the starter and all is well.

I gotta bleed the coolant system and clean up but otherwise its road worthy

I emailed spec several days ago if they sold a ring gear replacement and have not heard anything back

[The Dark Side of Will]

Replaced the flywheel with a standard steel autozone one. Also replaced the starter as it was bad.

I think the starter went bad which broke the teeth on the flywheel. I put it all back togethor with the same starter and it was still making twrrible noises when trying to start. Swapped the starter and all is well.

I gotta bleed the coolant system and clean up but otherwise its road worthy

Great to hear you got to the bottom of it.

I emailed spec several days ago if they sold a ring gear replacement and have not heard anything back

Spec? What do they know about GM FWD ring gears?

Pioneer FRG-142W. Steve at PTT told Pioneer is literally the only company that makes them.

[Shaun41178(2)]

The ring gear on the spec is different from every stock ring gear I have seen. Its been mqchined or cast differently than every online pic I have found of a ring gear.

I'll have to take a pic to show what I mean

[Shaun41178(2)]

Finally doing a heat exchanger. Mocked up

26x7 inches.

20211101_182635.jpg (4.7 MiB) Viewed 6069 times

[eHoward]

Thumbs up on the heat exchanger

[Shaun41178(2)]

Got it mounted. Drilled some 5 inch holes in the trunk in hopes some air will pass through.

20211106_141628.jpg (4.05 MiB) Viewed 5991 times

[jdv]

Put some small fans on it like from a transmission cooler.

[Shaun41178(2)]

Did a test tonight. Decklid is on. I drove normally and iats did rise 10 degrees higher than when engine was cold.

Turbo setup is radiating a bunch of heat into the trunk area and the heat exchanger isnt working as best it could.

I'll do another test with the decklid off and see if temps stay cooler.

[The Dark Side of Will]

Well your trunk is full of turbo hot side...
Maybe baffle or duct inside your trunk to get fresh air down to the HEX?

[Honest Don]

What are your IAT readings in relation to ambient temp when just cruising around?

[Shaun41178(2)]

Abput 10 degrees higher than ambient

[Honest Don]

Abput 10 degrees higher than ambient

I'm getting that with mine mounted up front.

What’s rise during and recovery after a pull like?

[Shaun41178(2)]

I checked my logs. I did a 1.8 second pull in 4th gear. I started at 3200 rpm and shutdown at 4500 rpm.

Boost maxed at 22.5 lbs.

Iat started at 69 degrees F. Rose to 76 degrees but that temp was well after i let off. Took about 36 seconds after rising to 76F to come back to 71 degrees Iat..

[ericjon262]

I checked my logs. I did a 1.8 second pull in 4th gear. I started at 3200 rpm and shutdown at 4500 rpm.

Boost maxed at 22.5 lbs.

Iat started at 69 degrees F. Rose to 76 degrees but that temp was well after i let off. Took about 36 seconds after rising to 76F to come back to 71 degrees Iat..

Nice

temperature sensors, especially air, are notoriously slow to react.

[Honest Don]

I checked my logs. I did a 1.8 second pull in 4th gear. I started at 3200 rpm and shutdown at 4500 rpm.

Boost maxed at 22.5 lbs.

Iat started at 69 degrees F. Rose to 76 degrees but that temp was well after i let off. Took about 36 seconds after rising to 76F to come back to 71 degrees Iat..

Tall order but, can you make it do that with the bumper cover?

[Shaun41178(2)]

I do plan to put the bumper back on soon actually.

I did another test tonight. Temps might have been lower 60s. Did a 3rd and 4th gear pull. This time I took the decklid off to help get hot air out of the trunk.

Temp started at 71 and rose to 79 when I let off in 4th.

I checked trunk temps when I got back and they were the same. I checked the turbo comp housing and it was reading 118 degrees. I didnt have a reading when the decklid was on.

Obviously with the decklid off temps around the turbo will be cooler. But the rear trunk wall and the heat exchanger seemed to be about the same temp as with the decklid on. The radiant heat from the downpipe is still getting it hot.

I should reroute the downpipe to exit out the decklid instead of down low where the heat exchanger is at