3.9L LZ9 engine internal upgrade & performance?

[bszopi]

Intake readings for sessions 3:

@ 0.600" lift = 273.80
@ 0.700" lift = 257.90

In all other sessions, your readings at 0.700" lift were higher (albiet slightly) than the readings at 0.600" lift.

[robertisaar]

Intake readings for sessions 3:

@ 0.600" lift = 273.80
@ 0.700" lift = 257.90

In all other sessions, your readings at 0.700" lift were higher (albiet slightly) than the readings at 0.600" lift.

THIS!

[mrtohil]

Ha! Yeah, don't what to tell you there. I also thought that that reading was weird. Especially how it falls off quickly after 0.600. To be quite honest with you I was a little nervous at the end of this session and what it meant. I think that ridge I mentioned before was really messing with my flow.

[mrtohil]

Just curious if anyone knows the specs for the stock valve spring. The specs I'm looking for are Seat Pressure, Open Pressure, Coil Bind and Spring Rate.
I found the installed height of 1.8in. Thanks ahead of time.

[carbon]

Sorry the format of that table bothered me...

Lift____________[0.100]_[0.200]_[0.300]_[0.400]_[0.500]_[0.600]_[0.700]_Avg CFM_Max CFM
Session 1(int)____62.4___128.6___186.8___218.9___232.1___238.5___NA______177.8___238.5
Session 1(exh)____52.6___100.0___138.2___150.1___154.7___155.8___156.5___129.5___156.5

Session 2(int)____67.1___131.9___191.1___236.0___250.0___257.3___261.1___199.2___261.1
Session 2(exh)____52.6___101.3___134.1___155.7___166.6___170.3___172.0___136.0___172.0

Session 3(int)____59.7___115.3___169.0___217.6___253.3___273.8___257.9___192.4___273.8
Session 3(exh)____53.4___102.0___136.9___157.5___165.5___169.6___172.0___136.7___172.0

Session 4(int)____63.3___125.4___187.2___238.7___263.7___265.1___266.2___201.4___266.2
Session 4(exh)____53.6___105.3___145.7___163.4___168.9___171.1___172.4___140.1___172.4

[mrtohil]

Hello everyone. Working again on this thing...hopefully to the finish. We'll see what new experiences happen this quarter. Did I miss anything while I was gone?

[mrtohil]

Quick question. Has anyone figured out if the cam bearings can be swapped out with something better? Similar to how you can swap 3.1L cam bearings with Chevy V8 cam bearings, but the V8 ones are better since they have more surface area. I know that the first cam bearing will need to be stock due to the size and oiling holes. But cam bearings two through four look normal.

[Nightingale]

i just went with the conversion bearings from cncguy to use gen3 cams. He uses the wider sbc bearings in his adapters plus you can get custom grinds easier this way.

[ericjon262]

So, I take it that you're going to ditch the VVT aspect of the LZ9? any particular reason why? I'm really liking this build. any plans to put the motor in a car?

[mrtohil]

Actually I am trying to keep the VVT function. And I'm planning on installing this engine (with the 6spd F40 trans) in a Beretta.

[mrtohil]

The latest is checking the valvetrain geometry and clearance. So far I checked the pushrod length to obtain the proper rockerarm to valve contact. The pushrods are going to be significantly shorter than stock. Once I got the length figured out I checked the valve to piston clearance. The first cam position came out okay. But with the cam in full advanced I found the exhaust valves hitting the pistons. The good thing is I have two extra pistons to try the cut with. Which later I would need since I really setup the angles on the machine wrong. I was finally able to obtain the angles directly from the valve guides to match them to the machine cutting head. The second test piston came out alot better. I also cut it deeper to clay and determine what actual depth was needed.

[mrtohil]

So I finished cutting the two pistons for cylinders 2 & 5. Now I have to reset the machine for the remaining four since the angles are different than before (thanks GM). I'll try to upload pics of this ASAP in Photobucket.

[trotterlg]

I would think the exaust valve would hit the piston when the cam was fully retarded, advance would get it closed earlier. Hope you aren't making your measurements backwards. Larry

[ericjon262]

what are you doing about a cam? stock regrind? might try calling someone like Mast motorsports and seeing if they can spec a VVT cam for you, they've been pretty big in the VVT tech R&D, so they might be able to help out...

[mrtohil]

Obtained a new stock cam . Had the lobes welded and reground. Work peformed by Racer Brown. Unfortunately the option of Mast wasn't available/known when I farmed the cam out. At the time I was looking for someone to make a cam for this engine, all the "big name" cam manufacturers wouldn't even look at it (out of fear of course). And just blew me off. Even a few British racing cams manufacturers wouldn't even look at it. Racer Brown was the only one who I called/emailed that even agreed to look at and into it.