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**neophile_17** · 02-20-2019, 10:03 PM

Originally posted by 1QUICKHATCH View Post

I believe that those 3400's also got the lx9 style PM rods... maybe they got a forged crank too! Lol

It's very possible. Considering the LX9 and LZ9 share the same stroke as the LNJ and classic LA1 it wouldn't surprise me in the least. the real question is would it be worth it to get the crank and rods from an LNJ to build the LA1 block you already have? I can't answer that but it would be interesting. Unfortunately I don't see a lot of activity around here so it might be awhile before we find out.
OTOH if anyone out there is interested in the bottom end I'd probably be up to buying the cam to help you recoup some of the cost of a whole engine.

**ericjon262** · 02-21-2019, 02:59 AM

I think it's just the three of us at the moment(actively on here) I didn't know the LX9 and LZ9 had the same stroke... learn something new every day! so far, I'm 2 for 2 on forged cranks, both were out of LX9's from G6 GT's, I think both were 2006 models.

**neophile_17** · 03-20-2019, 09:36 PM

Spotted an 07 Equinox cam on ebay and bought it. The sprocket mounting pattern doesn't look right in the photo which had me a little worried. After a little more research I saw a three hole non-VVT camshaft sprocket as Melling timing set 3700SC. I'll do some measuring when the cam arrives and then maybe order the timing set.

Could it possibly be the same bolt pattern as the old iron head timing set?

**neophile_17** · 03-28-2019, 11:29 PM

OK! So I've measured a few camshafts in the last 24 hours. Here is the boring warnings before I get into the details. All measurements were taken with a micrometer on the lobe itself by measuring the base circle and then the lobe 90 degrees apart. This is a Brown & Sharpe micrometer so not a Harbor Freight deal but I'm not an expert metrologist either. This means that lobe separation is not measured which is an important question. That being said here we go.

I took measurements of the following cams: LA1/LX9, LZ4, LNJ, and WOT-Tech Street/Strip.

The late 07 and presumably later LNJ camshaft have the same journal diameter as the LZ4/LZ9!

All three of the GM cams had the same lift- 0.271" +/- 0.001" which matches pretty close to the specs I've seen. I wouldn't swear to it but the center of the lobe seemed to have a slight crown- ie measuring the edge of the lobe yielded a slightly smaller lift than the center.

The WOT-Tech Street/Strip cam measured exactly to spec.

Take away thoughts: From my reading on the various forums I was under the impression that the LZ* cams with VVT had smaller lobe lifts such that the valve lift (with 1.7 vs 1.6 rockers) was the same as the LA1. My measurements show this not to be the case- the lobe lift is the same and the valve lift is greater by 1.7/1/6 = 106.25%.

If we take the best hp figure I can find for each engine I see that the LA1 has 185hp, LNJ has 185hp, LX9 has 215hp and LZ4 has 225hp. I'm going to attempt to draw a couple conclusions from these numbers based on the information I have. The LA1 and LNJ (both early and late) have essentially the same cam, rocker ratio, architecture, and hp so I will consider them the same. The LA1 and LX9 have the same cam, and rocker ratio, but the architecture is different. The argument could be made that ignition also changed but the LNJ has the same ignition as the LX9 but no more hp than the LA1. Assuming displacement is linear with hp the difference between a 3.4L and 3.5L accounts for about 5hp- not the 30hp difference between the LA1 or LNJ and LX9. So in the stock cam range the 3.4L engine definitely benefits from an architecture upgrade ie heads and intake. Now, going from the LX9 to the LZ4 one would expect that the obvious architecture improvements would make a significant improvement. This is not what we see. It looks like despite VVT the only improvement is from the additional valve lift offered by the 1.7 ratio rockers (valve lit increases by 6.25%). At his point it seems that the engine becomes cam limited. This is reinforced by the fact that the efficiency of the 3.5L in a 3.9L would yield 250hp but the LZ9 is rated at 240hp. So! There are a lot of assumptions here but, I tried to make them all clear and I'm more than willing to discuss any of their merits or lack there of. That being said if I was trying to upgrade an LA1 I'd focus my efforts on the heads/intake and for the LZ engines I'd start with a cam...which I know is expensive because I'm doing it now.

Other random thoughts: There is a good possibility that you could buy a LZ4/LZ9 from the junk yard and an LNJ cam timing sprocket that would allow you to run without VVT without much if any of a hp penalty. The crank sensor is still 58X or you'd have to get an external 7X sensor but eliminating VVT for $40 seems to be new.

**Guest** · 03-30-2019, 10:03 AM

If the lnj and lz9 have the same journal diameter then I wonder if the lnj uses the lz9 block.

The lz block is identified under the timing cover in the block itself.

Get some pics of the lnj cam. I am curious about the bolt pattern on it. Single bolt or 3? You might not be able to get new blanks cut from a cam company but they might be able to regrind it for more duration and lift.

Even if not, getting an stock lnj cam installed is easier than installing bearing spacers and new aftermarket cam.

When installing a wot tech cam in an lz9, a stock GM timing chain from a la1 can be used. I used one from an lx9 though.

The lnj cam should have a part number. Curious as to its cost

**neophile_17** · 03-31-2019, 11:34 AM