3.9L LZ9 engine internal upgrade & performance?

[mrtohil]

Hey guys. I'm doing a '06 3.9L for a high performance class. So I'll be boring, porting, etc. I've been looking around for performance upgrade info on this motor and can't find any. Has anyone done a project like this? Does anyone know what can be upgraded and with what (cam, pistons, valves, etc.)? Any info will be helpful. Thanks.
I will be taking pics during this whole project.

[Nightingale]

Pretty much just porting and polishing of the heads, have the camshaft ground, for pistons either custom or look into what Joseph Upson is doing with LS1 pistons, and last aftermarket valves are in the works through the 60degreev6 store according to the post Ben made about upcoming higher ratio roller rockers.

[SappySE107]

There isn't much available. I won't be doing any flow testing until this winter most likely and the valves will probably be winter as well (and rocker arms with higher ratios). There are no cams other than regrinding the stocker. I wouldn't want to take much off the base lobe since its a press on lobe cam.

[mrtohil]

Okay, the tear down has begun. I'm providing a link to my photobucket. I'll try to keep it up-to-date as much as possible. I should have new pics up every Friday night. I'll try to post what I find interesting. If there'e something you guys want more indepth pics of, let me know and I'll see what I can do. Enjoy.

http://s296.photobucket.com/albums/mm174/mrtohil/LZ9

[Joseph Upson]

Okay, the tear down has begun. I'm providing a link to my photobucket. I'll try to keep it up-to-date as much as possible. I should have new pics up every Friday night. I'll try to post what I find interesting. If there'e something you guys want more indepth pics of, let me know and I'll see what I can do. Enjoy.

http://s296.photobucket.com/albums/mm174/mrtohil/LZ9

I'm a long way from my extra block, if you could try and get a rough measure of the cylinder wall that would be nice. I was thinking of trying to punch and stroke one out to near 4.3 L with a 4" bore but I would need to have at least .180" wall thickness left afterwards.

Forged LS1 pistons can be had for half or less the cost of a custom set of 6 or 7 with rings. My set cost $381 shipped and you have several compression heights available to help accomodate an offset grind although you would need to go with chevy rods or down to the old V6 5.7" rod with an offset grind up to about .100"

[mrtohil]

All the measurement stuff should occur in the next few weeks. The block is pretty much bare and getting prepped for cleaning. I'll definitely post what this thing can be safely bored out to.

[Joseph Upson]

All the measurement stuff should occur in the next few weeks. The block is pretty much bare and getting prepped for cleaning. I'll definitely post what this thing can be safely bored out to.

The sooner you post that info the better because I'm nearly kicking myself for not taking those measurements the last time I was home as there's a sale on Mahle pistons similar to the ones I purchased but in a 4" bore. GM stated the engine was made to accomodate future increases in displacement.

I need the minimum cylinder wall thickness estimate and a clearance check on how much the crank can be stroked. The traditional small block chevy can already be stroked to well over 400 cubes, it would really be special if you could bump the 3.9L up to a 4.3L or more.

There are so many different compression ratios available for LS1 pistons the possibilities are many. Ebay is loaded with forged $250-328 chevy connecting rods to make a serious 60 degree V6 motor at a very low price. I really like these;

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=220282945139&ssPageName=STRK:MEWA:IT&ih=012

[IsaacHayes]

4.3L V6 just sounds nasty! And I'm not talking about the vortecs!

High compression, headered, 4.3l cammed 3900 would def be fun for N/A!!! I wonder what #s we'd be at with a setup like that.

[Nightingale]

Well I ordered up a shop manual for the g6 that supposidely has powertrain specifications. Hopefully it can be of some use to those of us trying to build up these badarse v6's. My machinest will be sonic testing the cylinder walls for me sometime next week when he gets his machine back from being recalibrated.

[mrtohil]

I was able to obtain some specs from the school. I have them on hand if you need them. The concern that I have is making a torque plate for this motor to bore it out correctly.
I don't see anything about min. cyl wall thickeness... WHICH MEANS it's okay to have paper thin walls to have max. bore.... Ha!

[Joseph Upson]

I was able to obtain some specs from the school. I have them on hand if you need them. The concern that I have is making a torque plate for this motor to bore it out correctly.
I don't see anything about min. cyl wall thickeness... WHICH MEANS it's okay to have paper thin walls to have max. bore.... Ha!

There is a pretty extensive spec sheet for the motor already available on the forum, it just can't be trusted fully. The rods are not 5.9" as advertised for example.

[bszopi]

http://60degreev6.com/content/3900_Engine_Specifications

[Joseph Upson]

Take measurements of the rocker arm bolt diameter at the top. The 3900 heads are designed after the LS1 heads, the rocker arms look identical although I suspect the bolts for the LS1 might be a little thicker. Since the pistons are interchangeable bore wise, if the rockers are also that would be another performance hurdle cleared. If they work and I believe they will, the possibility of building a very powerful 60 degree V6 without custom parts will be very easy. Here is a link to some nice LS1 rockers while it lasts;

http://cgi.ebay.com/ebaymotors/Scorpion-5-7-LS1-LS6-Roller-Rocker-Arm-Set-1-7-IE1098_W0QQcmdZViewItemQQ_trksidZp1742Q2em153Q2el1262QQcategoryZ33624QQihZ010QQitemZ200251509456QQtcZphoto

http://cgi.ebay.com/ebaymotors/_Car-Truck-Parts-Accessories__LS1-Comp-Cam-Pro-Magnum-1-75-Rocker-Arms-Camaro-Transam_W0QQitemZ250299223673QQadnZCarQ20Q26Q20TruckQ20PartsQ20Q26Q20AccessoriesQQadiZ2865QQcmdZViewItem?hash=item250299223673&_trkparms=72%3A543%7C39%3A1%7C65%3A12%7C240%3A1318&_trksid=p4506.c0.m245

[SappySE107]

Scorpion is making us rockers. They are close to the LS1 but not identical or compatible.

[Joseph Upson]

Scorpion is making us rockers. They are close to the LS1 but not identical or compatible.

Is that compared to the 3900 rockers also? they are different compared to the 3500 rockers and appear to be identical to the LS1 rocker. It was a close call from the picture though.