Is a tune REALLY required with CMDPs?

[MassMustang]

Probably a noob question, but I'll throw it out there.

I've been reading through a number of threads about CMDPs. If I already have a CAI & 93 Octane tune, is there any gain from just adding CMDPs? If I do a tune for the CMDPs, is the tune simply to disable the motor for the deleted plates only? I've read some cars ran fine without a tune and registered improvements on the butt dyno. I've read others used an actual dyno and saw no improvements. Others got a dyno tune after the CMDPs and saw ~25rwhp/~20rwt. Is that all tune and not much related to the CMDPs? They must add some improved performance at mid to high end, right? Plus some like the idea of no butterflies to reduce the risk of them sticking or breaking.

Reason I'm asking is I now have a pair of DIY CMDPs and would like to get them installed sooner than later. I'm saving for 4.10s first and don't want to spend $$ on a tune if I can avoid it. I'd rather a dyno tune but some etunes might be fine longterm as I only have basic mods so far.

Thoughts?

 

[MassMustang]

Oh, and mod plans for the next couple years would be (in order): CMDPs, 4.10s, longtubes with hi-flow catted h-pipe, cams. I'd probably buy an 07-10 GT500 before I put a blower on my 3V.

 

[weather man]

I think LITO saw a 2HP change controlling for all factors.

 

[07TGGT]

Yes, because the motors need to be turned off and the airflow is being effected.

 

[BruceH]

Yes it's needed. Many tables in the tune are based on cmcv open or closed. A tune will turn them off and if done right the tuner will copy all the open values to the closed tables.

 

[Grubb]

Good thread by Lito, changed my mind on CMDP's.
http://www.s197forum.com/forum/showthread.php?t=92072


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[JeremyH]

Yes you will throw a wrench light and go into limp mode if you just unplug the motor and don't adjust for airflow. A canned email tune to adjust for it can be had for fairly cheap.

 

[MassMustang]

Thanks for the thread link and advice. So a tune is required to avoid a CEL, and you would see some gains if a tune is applied. Guess pickup a tune from Bama or maybe the shop doing the gears to include the CMDPs.

 

[cbracoupe]

Yes it's needed. Many tables in the tune are based on cmcv open or closed. A tune will turn them off and if done right the tuner will copy all the open values to the closed tables.

 

[MassMustang]

Yes it's needed. Many tables in the tune are based on cmcv open or closed. A tune will turn them off and if done right the tuner will copy all the open values to the closed tables.

As I was thinking about this, open plates only had minor airflow interference and that's typically at higher rpms, right? So that's why you might only see minimal improvements. By copying the open table values to the closed table values, you'll then see improved performance midrange on up. Many people look at peak gains though, and forget the gains midrange (2500-4000?). So that may be why there's some many different opinions on CMDPs.

Bottom line, installation should be easy and worthwhile for a minor $ investment.

 

[JeremyH]

Don't really look at this mod as a performance one, although it may pick up a few hp. I look at it as protecting your motor, over time those valves are going to get gunked up stop functioning or break. There is a member on here that had a valve break and take out his motor.

 

[MassMustang]

Don't really look at this mod as a performance one, although it may pick up a few hp. I look at it as protecting your motor, over time those valves are going to get gunked up stop functioning or break. There is a member on here that had a valve break and take out his motor.

Makes sense. I'll confirm Bama will support my Predator and get a tune done. I may polish up the plates or powdercoat them in the meantime.

Thanks again for the insight.

 

[BruceH]

I think it's more like why some tuners suggest locking the vct. It's just easier to tune for.

As I was thinking about this, open plates only had minor airflow interference and that's typically at higher rpms, right? So that's why you might only see minimal improvements. By copying the open table values to the closed table values, you'll then see improved performance midrange on up. Many people look at peak gains though, and forget the gains midrange (2500-4000?). So that may be why there's some many different opinions on CMDPs.

Bottom line, installation should be easy and worthwhile for a minor $ investment.

 

[silverstang07]

I gutted mine but left the motor plugged in. Never an issue on my car.

 

[Swarzkopf]

^You're losing some low and mid-range power, though. With the difference in intake velocity/flow, you're able to command significantly higher ignition timing at a bunch of points throughout the band where the IMRC's are closed. You're in a lower velocity/higher flow situation- which can result in lower torque numbers - which is counteracted by adding ignition timing.

 

[MassMustang]

I figure I may as well get the "tunes for life" deal through Bama since I plan on other mods anyway. So I'll take advantage of the low-to-mid gains with a tune. I've gotta get 4.10s done, the CMDPs installed and possibly some LTs with hi-flow cats before the winter.

 

[06silverbullet]

i get my car smog tested with them on and stock factory tune, passes just fine everytime. you dont really need a tune but it isnt going to run very nice at lower rpm's where the air flow is restricted normally by the charge motion plates.

also i never once had a check engine light come on for them with factory tune installed.

 

[thump_rrr]

I think it's more like why some tuners suggest locking the vct. It's just easier to tune for.

Locking out the VCT is limiting the power potential of the motor since the cam timing will be set to make the most horsepower at peak only.
You will be losing potential gains below the curve.
Disregard this if dealing with extreme levels of boost such as 20+psi since I do not have any firsthand experience in this area.

A good tuner will get the most out of a 3V with the cams not being locked out.