3.9L LZ9 engine internal upgrade & performance?

The VVT can be made to work without a VVT PCM. You have to limit the cam range and have the module set to activate under the same circumstances consistantly so that you tune the engine to that function series. Dual VE tables would not be required as long as the cam retards at the same point everytime. Continued variance would require the proper PCM.

The problem with using a 3400 cam I believe is the area reduction under the curve and that's why I recommend a regrind of the stock 3900 cam. It has large lobes and a regrind could offer even more area under the curve without increasing duration if you wanted it that way.

The key is degreeing the cam in. The locked position is to far advanced probably as much as 20 degrees and as far as rpm is concerned the OE limit is about 6300 rpm, hardly an indication VVT is no good for high rpm. The initial peak hp ratings were at 6000 rpm per GM.

Limit the cam travel to a few degrees retard 4-6, I would think the ecm could compensate for that much anyway without extra tuning.

[IsaacHayes]

You could use the MegaSquirt for this. You could use the Nitrous/Meth injection output to activate it. Then you could use the Nitrous INPUT table switch. That means when activated it would switch to a different VE table tuned for the cam in that position....

That seems like the best way to actually use it. You could do the same for the variable intake.

Not sure what inputs the cam and intake phasers need to switch on, if it's PWM for inbetween points or what... Or if it will tolerate a solid voltage to just max on/off...


But yeah I would probably get a 3400 style cam in there with performance grind. If anything I would just play with the variable intake with a window RPM switch or with MegaSquirt if I had it. But more than likely I'd use the VVT 3500 UIM on it and be done with it.

A 3900 with a hot cam, high compression LS1 pistons and headers would put down a healthy amount of HP NA. If I was going to turbo I'd probably leave the pistons stock and stock cam, maybe a turbo cam later but with a turbo on the engine I'm sure it'd be a beast. Hell a 3400 is pretty crazy stock with a turbo....

[gectek]

the VVT events never work to your advantage due to alot of reasons. #1 this isnt VTEC people lol. #2 you have limited to no tunability for the VVT #3 they have to use a lobe that will work fully retarded or fully advanced #4 they are not made for excessive RPMS. I know in the LS engines, us going from a VVT 6.2L engine to running a straight cam that is very small by LS standards picked up over 30 HP everywhere. that means in the smallest part, 30 HP. When you try to use that same cam, it picked up a peak of 30. sabe?

Nightingale:

Do you have a thread or link to what you are doing with your LZ9? I would like to compare notes.

The problem I have with converting it to a 3400 cam is that I want to try retain the VVT function on this motor. But if the VVT can be retained while still being converted to a 3400 cam...that would be great!

You can't do it. The VVT cam is a unique and non interchangeable design. You can use it as is however you would need to degree it in so that it is not excessively advanced in order for it to provide optimum power. You can then limit it to a small amount of retard action since some of the range is devoted to EGR like function and may actually reduce performance. The best route is probably to have the OE cam reground to performance specs and installed at the correct degree angle and left alone.

[mrtohil]

Nightingale:

Do you have a thread or link to what you are doing with your LZ9? I would like to compare notes.

The problem I have with converting it to a 3400 cam is that I want to try retain the VVT function on this motor. But if the VVT can be retained while still being converted to a 3400 cam...that would be great!

[Nightingale]

Might be able to order a set of valves from manley if Ben has some part numbers from the prototype valves he had made. I bought his extra set for my project. They are the manley race flo stainless steel intake and exhaust in standard lz9 size. Also for a camshaft you can go the route I am, which is to use the 3900 to 3400 bearing spacers CNCguy made up. Should be nice now that you can order custom grinds specific for your application through the store.

[gectek]

really hard to install LS1 valves. they are too large. WAY too large. same design, but diff ballpark

[mrtohil]

I have obtained the forged connecting rods from Cunningham Rods. I also had a torque plate made to properly hone the bores. I have placed the pics on photobucket. I'm still having issues getting the camshaft made. Also seeing how hard it will be to install LS1 valves. I will try to update the thread as much as I can.

[robertisaar]

good stuff...

[mrtohil]

I've had the transmission gears,shafts and ring gear sent out to get cryo'd and micro-polished. I've also obtained the limited slip from Quaife. The pics for the LSD, before and after pics of the gears and shafts are posted on my photobucket. The procedure was performed by Evan Performance in Atlanta,GA. Good work!

[mrtohil]

Latest update.... I'm having my camshaft made be Racer Brown. The connecting rods are being made by Cunningham Rods. It'll be about 2 months time to make. Which unfortunately will be outside the window for the final quarter for school. Looks like I'm going to have to take the course again...this fall...could be worse.

[mrtohil]

I also want to inform that I currently disassembling the 6spd manual that comes mated with the LZ9...the F40. I am also taking pics and posting in under my photobucket. I'll be posting what I find here also.

[mrtohil]

I checked the volume on my heads. I think GM was shooting for 36cc. I got 36.4cc on head "A". 35.8cc for head "B". After decking the heads I ended up with 33.5cc on "A". And 34cc on "B".

[SappySE107]

You don't size headers by flow on a bench and you shouldn't port exhausts out to gaskets or flanges. Flowing without a tube gives you a false peak reading as well.

Ill have more 3900 flanges soon but they are meant for 1.75" tube. Primaries are sized by output of the motor and also powerband.

[mrtohil]

I used the clay on the intake. The exhaust was left open. Later this quarter I will get different sized tubing to find which works optimaly with these heads to make headers.
Before I forget, wasn't there someone selling exhaust header flanges for 3.5/3.9? I've been looking for them to be able to port the exhaust correctly and so I do that exhaust tubing test later. And if someone has a picture of the exhaust manifold to exhaust manifold gasket relation, that would be awesome! I'm not really looking forward to buy some stock exhaust manifolds so I can port correctly only to not used them because of the headers made.