Carbahn 4.6l - Cam or No?

[dpeete]

Thank you in advance for help. I am looking for informed opinions from folks who have built engines. I’ve read through what I can find on the forums and spoken live with one owner, but still not confident in what would be the best fit for me.

Car Situation: after a main bearing failure in my 2011 M3, my engine is in queue at Carbahn for a 4.6l build. The initial recommendation was for the base 4.6l build. But I am questioning if I should get the cams or not. In general, I get the recommendation for emphasizing the low end torque, but I have the 4.10 differential, which seems like that plus the larger displacement would makeup for any loss in low end torque. It would seem the combination would still result in more available low end torque than a stock M3.

Me: I do not track the car, but I am former SCCA racer, so my definition of “canyon run” might be more than the average bear. And while I could move to a newer car, I am making the choice to stay with the M3 because I value this generation of M3 over newer turbocharged cars and their electric steering.

Final data point: car is a California car, so I need to pass smog. The only exhaust mod is the Dinan catback… I have the stock cats and x-pipe.

Will the 4.6l with cams pass CA smog diagnostic with stock software? (I am fine with flash/reflash for testing, but I need the car to be able to pass the “sniffer tests” without much additional hassle)

Any thoughts on cams given the above parameters?

And I assume it is 292s or nothing… for the additional money the 284s don’t seem worth it for this build. Is that a bad assumption?

Thank you for your thoughts.

[darren p.]

Don't have a built bottom end but if it were me I would go with the 292s and the 4.6...the low end that you would lose with those cams would be made up for with the additional displacement and the 4.10 gears you already have. Don't think you'll have any issues with the cams and the 4.6 with the stock headers and X-pipe as far as emissions go. Ideally intake and head work along with a set of headers and an X-pipe with a custom tune to maximize the 4.6 w/ 292s but CARB would likely make the hassle not worth the trouble, would not be fun swapping headers in/out every couple of years. Kudos for sticking with the platform after your loss, its a tough pill to swallow but I agree with your dedication to the platform for the reasons you stated amongst others.

I would probably agree with your assumption that 284s on the 4.6 would not be worth it but there is not a lot of data on this topic. I'm currently trying to figure out which cams to use on a 4.0 but 4.10 gears are going in either way for me, that is for sure.

[alfalfa]

Originally Posted by dpeete

Final data point: car is a California car, so I need to pass smog. The only exhaust mod is the Dinan catback… I have the stock cats and x-pipe.

Will the 4.6l with cams pass CA smog diagnostic with stock software? (I am fine with flash/reflash for testing, but I need the car to be able to pass the “sniffer tests” without much additional hassle)

Any thoughts on cams given the above parameters?

Your problem with stock ecu software will start with the different displacement of the 4.6. There are different methods for software solutions for this but with stock ecu software you are completely relying on adaptations and they have a maximum range. With luck you are in this maximum range.

With additional 292 cams this will not work with stock software.
Even after cat heating cycle where there engine will run like shit and shake as hell you will get problems due to the different air mass in the obd relevant range. The fault codes which will appear can't be hidden and so your smog test will fail. With cams it's a 100% problem and without cams you may have luck and the plausibility checks offer this range.

And if you are using your stock x-pipe even with another tune for 292 cams the engine will not run healthy.

[dpeete]

Originally Posted by alfalfa

Your problem with stock ecu software will start with the different displacement of the 4.6. There are different methods for software solutions for this but with stock ecu software you are completely relying on adaptations and they have a maximum range. With luck you are in this maximum range.

With additional 292 cams this will not work with stock software.
Even after cat heating cycle where there engine will run like shit and shake as hell you will get problems due to the different air mass in the obd relevant range. The fault codes which will appear can't be hidden and so your smog test will fail. With cams it's a 100% problem and without cams you may have luck and the plausibility checks offer this range.

And if you are using your stock x-pipe even with another tune for 292 cams the engine will not run healthy.

And apologies for fact checking, but is this based on your experience, or are you speculating based on other posts?

[alfalfa]

Its is no speculating. Its real world experience from my 4.5l stroker with 292 cams engine.

[M3SQRD]

I’m not sure if you’re familiar with this 4.6 L 292 cams stroker build with stock ecu (custom tune) but it has no cold start, cold idling or cold drivability issues. BW headers and x-pipe can be replaced with stock headers and x-pipe.

https://www.m3post.com/forums/showpo...98&postcount=1

[dpeete]

Originally Posted by alfalfa

Its is no speculating. Its real world experience from my 4.5l stroker with 292 cams engine.

Thank you for the clarification.

[dpeete]

Originally Posted by M3SQRD

I’m not sure if you’re familiar with this 4.6 L 292 cams stroker build with stock ecu (custom tune) but it has no cold start, cold idling or cold drivability issues. BW headers and x-pipe can be replaced with stock headers and x-pipe.

https://www.m3post.com/forums/showpo...98&postcount=1

Thank you. The trick here is that we cannot pass smog in California with non-CARB approved software. And there isn’t software designed for this engine that i CARB approved. So I was hoping that it could get by the sniffer test with stock software (or the Dinan software I have for the stock motor), and then swap it to the 4.6l tune after.

[M3SQRD]

Originally Posted by dpeete

Thank you. The trick here is that we cannot pass smog in California with non-CARB approved software. And there isn’t software designed for this engine that i CARB approved. So I was hoping that it could get by the sniffer test with stock software (or the Dinan software I have for the stock motor), and then swap it to the 4.6l tune after.

Same thing applies where I live. Every other year I have to reload the oem software. I believe Danny’s stroker build would run on the oem software. His current software is a dyno tuned stage 2. I’ll ask him and then let you know what he says.

[omgzirra_exe]

the 4.6L will run on the OEM flash and will pass smog with cams and stock x pipe, but i wouldn't rip on it. the oem tune will take some time to adjust for the extra fueling needed, but it will get the car running and run well enough to get the smog readiness done.

but after that i would immediately flash it to it's optimal tune from carbahn.

[M3SQRD]

Originally Posted by dpeete

Thank you. The trick here is that we cannot pass smog in California with non-CARB approved software. And there isn’t software designed for this engine that i CARB approved. So I was hoping that it could get by the sniffer test with stock software (or the Dinan software I have for the stock motor), and then swap it to the 4.6l tune after.

The 4.6 L will run on the stock oem software. Apparently, the software can also be adjusted for the new stroker displacement.; i.e., you can tell the ecu it’s a 4.6 L.

[alfalfa]

Originally Posted by M3SQRD

The 4.6 L will run on the stock oem software. Apparently, the software can also be adjusted for the new stroker displacement.; i.e., you can tell the ecu it’s a 4.6 L.

You can flash the GTS 4.4 software and will see it will not work cause it checks if the car is a GTS or CRT. Deactivated this check ends up in a software change and the CAL ID/ CVN will not match anymore (what they will check in California as fas as I know).
Tell the ecu the different replacement also ends up in a software change and the CAL ID/CVN will also not match anymore.

If the CAL ID/CVN is not checked than it's no problem to get it properly running for smog test even with cams and stock x-pipe.

[SYT_Shadow]

If i had to do it again, I'd definitely do cams again.

Our stroker is still going strong after all this time

[ab987]

Originally Posted by dpeete

Thank you in advance for help. I am looking for informed opinions from folks who have built engines. I’ve read through what I can find on the forums and spoken live with one owner, but still not confident in what would be the best fit for me.

Car Situation: after a main bearing failure in my 2011 M3, my engine is in queue at Carbahn for a 4.6l build. The initial recommendation was for the base 4.6l build. But I am questioning if I should get the cams or not. In general, I get the recommendation for emphasizing the low end torque, but I have the 4.10 differential, which seems like that plus the larger displacement would makeup for any loss in low end torque. It would seem the combination would still result in more available low end torque than a stock M3.

Me: I do not track the car, but I am former SCCA racer, so my definition of “canyon run” might be more than the average bear. And while I could move to a newer car, I am making the choice to stay with the M3 because I value this generation of M3 over newer turbocharged cars and their electric steering.

Final data point: car is a California car, so I need to pass smog. The only exhaust mod is the Dinan catback… I have the stock cats and x-pipe.

Will the 4.6l with cams pass CA smog diagnostic with stock software? (I am fine with flash/reflash for testing, but I need the car to be able to pass the “sniffer tests” without much additional hassle)

Any thoughts on cams given the above parameters?

And I assume it is 292s or nothing… for the additional money the 284s don’t seem worth it for this build. Is that a bad assumption?

Thank you for your thoughts.

For my 4.2, the 284s were quoted at +18hp over stock cams, and the 292s were quoted at +22hp. So 284 vs 292 for a 4.6, you'll still be seeing single-digit HP gains, most of the cam gains are had with a 284. If the extra few hp is worth an extra $1000, that's a question you'll have to ask yourself. On the other hand, you're already over $30k into this, so what's another $1000

[alfalfa]

Originally Posted by ab987

For my 4.2, the 284s were quoted at +18hp over stock cams, and the 292s were quoted at +22hp.

Who made this quotes?

[M3SQRD]

Originally Posted by alfalfa

You can flash the GTS 4.4 software and will see it will not work cause it checks if the car is a GTS or CRT. Deactivated this check ends up in a software change and the CAL ID/ CVN will not match anymore (what they will check in California as fas as I know).
Tell the ecu the different replacement also ends up in a software change and the CAL ID/CVN will also not match anymore.

If the CAL ID/CVN is not checked than it's no problem to get it properly running for smog test even with cams and stock x-pipe.

I added the statement about being able to alter the displacement of the s65 in the stock ecu as an “FYI”.

However, I clearly stated you can run a stroker with 292 cams on 100% stock ecu software + stock x-pipe which was answering the question from a previous post.

The state of MD checks for altered software so I am aware of the ecu checksum and CAL ID/CVN matching identically oem software parameters.

[alfalfa]

Originally Posted by M3SQRD

However, I clearly stated you can run a stroker with 292 cams on 100% stock ecu software + stock x-pipe which was answering the question from a previous post.

Your own experience especially for smog test as questioned above?

[ab987]

Originally Posted by alfalfa

Who made this quotes?

Dinan/Carbahn

[M3SQRD]

Originally Posted by alfalfa

Your own experience especially for smog test as questioned above?

It’s from my friends 4.6 L stroker build and the use of the oem ecu and software. It was eventually custom tuned for the 292 cams, BW headers, BW forward x-pipe designed to work with the the BW headers collectors and Karbonius CF plenum. 490 whp, 365 lbf-ft. Like I stated in my earlier post, I said I’d ask him about whether you can run the stock ecu software and cats on a stroker with 292 cams. His answer was yes. I never stated I had a s65 stroker.

[Thumbie]

Summarizing:
so the Carbahn stroker w/ cams will run on stock tune? Sounds like it will.
Do some settings within the software need to be adjusted to help? Sounds like potentially, yes.
Will the stroker run good enough on the stock tune (with or without adjustments) to pass California /CARB smog? And is it safe? This is the question.
Dinan is (was?) a CA based company. Has anyone reached out to them directly?

Mostly here to sub as I plan to go the 4.2L +cams route if my stock motor fails

[spammysammich]

Don’t confuse Dinan and Carbahn.

[Thumbie]

Good point.

I guess I meant reach out to Carbahn directly. And since old Dinan was in CA, maybe people at Carbahn have some experience there.