LNF: Let's talk cams

[mkriebs]

Simply because I am bored and craving my winter-time theory conversations... I don't know if anyone in here is good with cam theory, it is certainly something I am not very good at, but I want to begin a discussion (might not be a good idea since I don't know enough about cams to be speaking about it), I know enough to be dangerous, and that's not good lol. Add in the continuous valve timing and it gets more difficult. I also do not know tolerances of the LNF such as how much lift we can fit, but intend to find out when I get in my new shop.

First, understanding that this is going to be a totally different discussion for different cars and power levels and uses, let's assume this is a 600whp EFR turbo'd LNF built for road racing. Extreme, but not out of reach.

Addressing the cam timing first, we have seen decent gains with this already, but I am positing that possibly the gains would be even more vast with bigger cams. I think with bigger cams this may help us smooth the idle out some on big cams, while being able to really roll in the steam on the top end. I think comparing this to something like the EVO's MIVEC system is going to be as good as we can get, granted, it's not controlling both cams.

Now, comparing the ZZP Stage 2 cams to other cams in the turbo sport compact scene, the ZZP cams are quite tame. For this, I think I would compare it to the 4g63 cams that BC, AMS, and others offer. I know ZZP has stage 3 cams out there, and I would like to see the specs on those. Maybe Matt M could chime in on those.

ZZP Stage 2: 224°/218° duration (assuming at 0.050" lift) .438"/.420" lift
Brian Crower Cams Evo VIII: 276°/276° total duration 216°/216° duration at 0.050" .436"/.436" total lift
GSC Evo VIII Stage 2 cams: Intake 274°/274° total duration .440"/.433" total lift
Kelford Evo IX MIVEC Cams: 272°/278° total duration, .433"/.433" total lift

Can anyone speculate to the benefit we could have by running higher duration and the max lift we can fit in the LNF? Does the lift get complicated with the variable vale timing, surely at some point it comes into interference with the pistons. I know the implications of running larger lift and more duration, rough idle, loss of low end power (if not done correctly). The great thing about the LNF is we tune the overlap, it's not like the pushrod V8 motors I am used to.

Thinking I might look into having some custom grinds made in some different specification than ZZP offers. I think we could certainly pick up some more power. Unless I could get stage 3 specs and get a set.

[CDNITE]

Last time I remember I played with the Cams and the forum went down this road, it was determined that there are still cam controls that aren't unlocked with HPTuners. Like the cam HPFP lob count. It is unlocked on the delphi ECUs but not the Bosch. This one feature alone would help make tons of "safer" "easier" power.

Maybe ZZP has figured out more solutions... I kinda fell out of the up to dates since my car has been going through a "upgrade", but since that is hopefully finishing up soon I'd love to see what we can figure out!

--Christian

[cobaltssoverbooster]

ground .035" off base circle for a race setup on a full port...check engine light never turned off due to rough idle running.
the signal review specs hard coded for the crank signals misfire error are very tight. any large overlap cam from extended duration results in a code that never goes way.
see lopy show cam tune files, happens with factory cams when you move them into massive overlap at idle. the solution would be to change lsa on the cam to a wider spread under high duration, otherwise you get to keep running your check engine light.

oh and disabling the crank sensor code makes a no start on 2008/2009 ecu's. those are the only two I've tried that on.

[MikeM173]

I wrote a cam thread up if you want to read it then post questions here. Bill had some good inputs in there as well.

[CDNITE]

I wrote a cam thread up if you want to read it then post questions here. Bill had some good inputs in there as well.

Maybe drop a link for those interweb is not strong with.

[CDNITE]

I never got any codes or CELs when I ran my lopey idle.

An interesting artifact that does happen with it is 3 out of 5 times I load the same tune file the cams won't move out of the parked idle location.

Doing a write all or write changes doesn't seem to make a difference.... I meant to post a thread on this phenomena but I forgot....

--Christian

[Matt M]

ZZP S2 LNF cams are 216/212 @ .050"
Duration numbers on the product page are listed at 1mm. We do that because the specs that GM release for the factory cams are measured that way.

ZZP S3 LNF cams are the same duration and lift as S2. The difference is the pump lobe lift is increased .075" over stock vs. .050" for S2. S3 cams also have the reluctors offset and get installed with nearly 30 degrees less LSA. This sets them up ideal for high rpm which is important because the cam actuators park on their seats at anything above 7400 rpm. There is still plenty of adjustment for cruising and acceleration, but the cams are no longer able to be set with the wide LSA typically utilized at idle. This means that the S3 cams cause a lopey idle.

[Area47]

Matt. do you have anything internally done to the cam actuators?

[Matt M]

Some of them had stops installed to limit the phasing in case of failure or bad ecm programming. Then I set them up and tested and found they still had .050" piston to valve clearance worst case. The last couple we set up do not have internal modifications.

[mkriebs]

ZZP S2 LNF cams are 216/212 @ .050"
Duration numbers on the product page are listed at 1mm. We do that because the specs that GM release for the factory cams are measured that way.

ZZP S3 LNF cams are the same duration and lift as S2. The difference is the pump lobe lift is increased .075" over stock vs. .050" for S2. S3 cams also have the reluctors offset and get installed with nearly 30 degrees less LSA. This sets them up ideal for high rpm which is important because the cam actuators park on their seats at anything above 7400 rpm. There is still plenty of adjustment for cruising and acceleration, but the cams are no longer able to be set with the wide LSA typically utilized at idle. This means that the S3 cams cause a lopey idle.

Well, damn. That is some awesome information, thank you for sharing that Matt. Are we able to get the S3 cams, if I contact you directly? It's not something I need right now, but definitely something I intend to need in the long run. That fuel lobe would be nice, too! Have you noticed any decrease in reliability of the fuel pump with the bigger fuel lobe?

Wondering if there is any benefit to reclocking the phaser on the OEM cams?

I am more well-versed on pushrod cams, totally different when you add another cam plus continuously VVT.

[mkriebs]

I wrote a cam thread up if you want to read it then post questions here. Bill had some good inputs in there as well.

I have looked, maybe I overlooked it. I found a great one on cam timing, but nothing about actual cam sizing.

[MikeM173]

I apologize I quick glanced at this post when I responded which is why I gave it a vague answer since I didn't have much time at that moment. I have only heard rumors on some cam things but I haven't actually had the extra cash that I wanted to throw at investing into it. Overall it would be cheaper then ZZPs cams but then you run into the issues of it hasn't been tried and trued and you don't have a company backing it so if a part gets messed up you'll end up spending more in the long run since the company backing the product ends up sending you a replacement if they sent you a jacked up part. Ends up making you not feel so bad spending the cash on ZZPs. It would be nice to see someone else come out with something else. If someone wants to back the cash for me I would love to try it out and test them on my car. Like I said I have a few ideas. Of course ZZP is way ahead of anything I would create any time soon and I have never heard a bad thing about their cams other then price but everyone hates spending money so take that lightly.

[mkriebs]

I apologize I quick glanced at this post when I responded which is why I gave it a vague answer since I didn't have much time at that moment. I have only heard rumors on some cam things but I haven't actually had the extra cash that I wanted to throw at investing into it. Overall it would be cheaper then ZZPs cams but then you run into the issues of it hasn't been tried and trued and you don't have a company backing it so if a part gets messed up you'll end up spending more in the long run since the company backing the product ends up sending you a replacement if they sent you a jacked up part. Ends up making you not feel so bad spending the cash on ZZPs. It would be nice to see someone else come out with something else. If someone wants to back the cash for me I would love to try it out and test them on my car. Like I said I have a few ideas. Of course ZZP is way ahead of anything I would create any time soon and I have never heard a bad thing about their cams other then price but everyone hates spending money so take that lightly.

I believe you're right. The ZZP cams are the only offering out there and now that Matt explained them a bit, they actually seem pretty beefy. I was more looking to start a conversation on the theory behind sizing 4 cylinder turbo cams, because I am not well versed on it. The OEM cams seem to do an okay job, but of course I can't leave well enough alone and would like to see what limits and bounds can be pushed.

I would venture into custom cams myself, I have some contacts, but the issue is the direct injection. Would be interesting if a different ECU finds its way into the car if changing fuel lobes would offer a better result for fueling. Theoretically, I could see a 4 lobe fuel lobe being beneficial, as long as there is a lift pump to keep the HPFP supplied.

Wish GM had just put a gear driven pump on these things like the diesels!

[Matt M]

Well, damn. That is some awesome information, thank you for sharing that Matt. Are we able to get the S3 cams, if I contact you directly? It's not something I need right now, but definitely something I intend to need in the long run. That fuel lobe would be nice, too! Have you noticed any decrease in reliability of the fuel pump with the bigger fuel lobe?

Wondering if there is any benefit to reclocking the phaser on the OEM cams?

I am more well-versed on pushrod cams, totally different when you add another cam plus continuously VVT.

HPFP wear does not seem to be substantially increased. I imagine there is added stress, but nothing that has caused a bunch of failures.
Yes, I could set up some S3 cams for you.

[Matt M]

I believe you're right. The ZZP cams are the only offering out there and now that Matt explained them a bit, they actually seem pretty beefy. I was more looking to start a conversation on the theory behind sizing 4 cylinder turbo cams, because I am not well versed on it. The OEM cams seem to do an okay job, but of course I can't leave well enough alone and would like to see what limits and bounds can be pushed.

I would venture into custom cams myself, I have some contacts, but the issue is the direct injection. Would be interesting if a different ECU finds its way into the car if changing fuel lobes would offer a better result for fueling. Theoretically, I could see a 4 lobe fuel lobe being beneficial, as long as there is a lift pump to keep the HPFP supplied.

Wish GM had just put a gear driven pump on these things like the diesels!

That's what I like about the ECMs in the Regal and ATS. On those you can adjust the pump event timing and even set them up for more or less pump lobes. The ATS uses a 4 lobe fuel pump drive.

[mkriebs]

Cool, Matt. Any idea if there would be a way to fit the 4 lobe cam in the LNF if I did indeed have success in changing the ECU? Have you guys explored this at all? I will get a hold of you for cams, looking to do an EFR set up here soon once I get set up in my new shop.

Matt, since you guys are the most development oriented for the LNF, have you guys ever pushed a stock bottom end LNF to it's limits, but with a larger ring gap? I am looking at all the Stock bottom end LS motor stuff and they open the ring gap some, I have been thinking this would be something to possibly try on the LNF (can't hurt, right?).

[Matt M]

Cool, Matt. Any idea if there would be a way to fit the 4 lobe cam in the LNF if I did indeed have success in changing the ECU? Have you guys explored this at all? I will get a hold of you for cams, looking to do an EFR set up here soon once I get set up in my new shop.

Matt, since you guys are the most development oriented for the LNF, have you guys ever pushed a stock bottom end LNF to it's limits, but with a larger ring gap? I am looking at all the Stock bottom end LS motor stuff and they open the ring gap some, I have been thinking this would be something to possibly try on the LNF (can't hurt, right?).

Yes, we actually have a 4 lobe LNF cam kicking around here somewhere. We tested it a few years ago, but abandoned it after the larger 3 lobe testing was so successful. The LNF is already designed as a turbo application, so changing the ring gap should not be as critical as a boosted LS motor. Either way, we surpassed 600whp before a rod snapped and ended the fun. Problem is that the rods in my original bottom end were bent and that motor was only at 500+ whp briefly.

[mkriebs]

Yes, we actually have a 4 lobe LNF cam kicking around here somewhere. We tested it a few years ago, but abandoned it after the larger 3 lobe testing was so successful. The LNF is already designed as a turbo application, so changing the ring gap should not be as critical as a boosted LS motor. Either way, we surpassed 600whp before a rod snapped and ended the fun. Problem is that the rods in my original bottom end were bent and that motor was only at 500+ whp briefly.

I tend to agree with it being a turbo application already that it should not be a problem, but the most common cause of snapped ring lands is either too tight of ring gap, or detonation. I am sure the latter is an issue for most of the "tooners" out there, but I think we have a fairly elite group on this board, which I guess there has not been an issue with popped ringlands either. That may answer my question. So it seems like the rods are the weaker point with proper tuning. I know John's motor had some nice custom shaped rods and he was running around 500whp.

And not that it's all that expensive to build the bottom end, your rods and wiseco pistons and you're sitting just over $1k, I was just curious.

[codename Bil Doe]

Any suggestions as to a safe upper limit on stock rods? 475? Those are two confirmed 500whp bends.