DOD hardware and cam choices

[G8GXP4now]

I know you can simply turn off DOD via programming.

Does leaving all the DOD hardware in place limit how big of a cam you can use even if the DOD never kicks in?

Or is it better to just convert to the NON DOD setup?

[wreckwriter]

Better to convert but much pricier as heads must come off. Check with Mike at New Era as to DoD cams.

[Ktlplxm]

Yes it does because of the lifter and "lifter tray" design. Once you have it down that far already (the engine) just install the LS7 or Cadillac race lifters in their place along with the proper lifter trays. If you dont change the tray you can spin the lifter.

[G8GXP4now]

So this is really another hidden benefit of just starting out with a GXP as it has a decent cam and no DOD crap to mess with. I think I saw the prices to convert to non DOD was about $1200 in parts plus labor.

[Andy@Livernois]

So this is really another hidden benefit of just starting out with a GXP as it has a decent cam and no DOD crap to mess with. I think I saw the prices to convert to non DOD was about $1200 in parts plus labor.

yep, we sell our kit with all the necessary parts for $1239... Unfortunately the stock DOD lifters aren't too happy even in their current stock application... best just to play it safe and get rid of the system, believe it or not a more aggressive cam sometimes can actually help your MPG because of reduced pumping loss, more overlap for a natural EGR effect, and since you are making more power you don't need to be on the go pedal as much :D

[MANOFSTEEL69]

Not really a hidden benefit. But you can get as much bang for your buck without spending the mony on a GXP by modding the G8. Unless you want bigger brakes and a stick, the G8 is the more economical choice. I'm at a higher HP than the GXP and under the cost of one. As for keeping the DOD with changing the cam....I wouldn't recommend it.

[Ktlplxm]

Not really a hidden benefit. But you can get as much bang for your buck without spending the mony on a GXP by modding the G8. Unless you want bigger brakes and a stick, the G8 is the more economical choice. I'm at a higher HP than the GXP and under the cost of one. As for keeping the DOD with changing the cam....I wouldn't recommend it.

I'm on board with MANOSTEEL69, with only 30K tied up in my entire car I had way more power than the GXP. The DOD isn't really much of a hassle though, never have seen why people complain about it. You can still find good cam selections with it active, but the non DOD is probably better in the long run (unless you had to do it when GM had all the lifter trays on back order and after calling EVERYWHERE only one place, New Era, had them...my luck as always lol)

[G8GXP4now]

I'm on board with MANOSTEEL69, with only 30K tied up in my entire car I had way more power than the GXP. The DOD isn't really much of a hassle though, never have seen why people complain about it. You can still find good cam selections with it active, but the non DOD is probably better in the long run (unless you had to do it when GM had all the lifter trays on back order and after calling EVERYWHERE only one place, New Era, had them...my luck as always lol)

You must have either done most of the work yourself or got one hell of a deal when you got the GT. I am not implying that the GXP is a better deal, I was just throwing out another cost to convert a GT to GXP that usually isn't mentioned.

[Ktlplxm]

Oh I did get one hell of a deal and did most of the early work. I only paid 25K for mine. I don't think its normally mentioned because a cam change isn't necessary to make GXP numbers, but you did bring up a valid point of consideration

[Ed Curtis]

I know you can simply turn off DOD via programming.

Does leaving all the DOD hardware in place limit how big of a cam you can use even if the DOD never kicks in?

Or is it better to just convert to the NON DOD setup?

Don't be afraid of retaining the DOD valvetrain if that is your mandate. When you install the correct parts and have the right shop in your corner, you can obtain some big gains in power without sacrificing reliability.

Mike from New Era Performance Parts in Rochester, NY has be way ahead of the curve on getting these DOD-spec camshaft packages to the G8GT enthusiasts. The GMPP Shoot-out in Memphis last year proved that retaining the DOD is not a liability and quite reliable. A lot of the information is covered in this article in Chevy High Performance magazine.

DOD Camshaft Information (http://www.chevyhiperformance.com/tech/engines_drivetrain/cams_heads_valvetrain/0902chp_camshaft_and_valvetrain_technology_insight/flowtech_induction_valvetrains.html)

Mike is now doing more work to the combination with a little head work and a few small tweaks. After inspecting the lifters, push rods and the rest of the valvetrain, absolutely no problems were seen. So much for the fear mongering of DOD cam swaps.

[johnh]

So this is really another hidden benefit of just starting out with a GXP as it has a decent cam and no DOD crap to mess with. I think I saw the prices to convert to non DOD was about $1200 in parts plus labor.

Hmm..GXP about $5700 more than a GT. Wanna bet you can easily get 100 hp more than a GXP for that?

[Andy@Livernois]

What you don't understand is people said the same crap about the Ford 3-valve engine as well... The VCT system was fine because this person or that person hasn't had a failure. Now everywhere you look people have issues with that system, so much so there are multiple manufacturers that make systems to help or delete this system. These parts didn't start to become prevalent until about a year ago, once enough had failed and cost massive amounts of engine damage to get peoples attention... We were the first ones out with this delete system for the 3v almost a full year before anyone else had it out, and most people then said it wasn't needed, yet now most shops REQUIRE these parts before they install a camshaft, many of these are the same shops that denied a problem existing.

Trust me, there is a reason GM uses such pansy camshafts with this system, and such lightweight valve springs... There is even a reason the lobes are even less aggressive on the cylinders that have the special lifters compared to the normal lifters... It has ZERO to do with what shop installs/tunes/etc... there is a limit to the stock part, once it's past that limit it's simply a matter of WHEN, not IF.

I guess working for a TIER 1 supplier skews it a little, but there were all kinds of issues with this system, and the trade offs listed above were required trade offs to make this system work...

I guess the way to look at it is this:

why do you want a cam that retains DOD? DOD does not help economy as much as people think, and with the right combo you can get the same economy as the DOD setup and a smaller cam as with a larger cam and canning the DOD...

Jay (manofsteel69) said he got about 24-25mpg on the way to the shop making over 400rwhp and NO DOD. Most of the cars we get average 25-26mpg with a CAI and a tune only... so really it was 1mpg loss compared to retaining DOD. Jay would probably get better if he didn't drive like an A-hole all the time ;)

Why risk it?

[Ktlplxm]

Andy has a point about the mileage. Even with a 60 more cubic inches, head work, camshaft, induction, exhaust, etc., I can maintain 22mpg normal driving, 23-24 mpg conservatively driven. When it was just an L76 cam, induction, exhaust, I still maintained 24 mpg vs my 25 stock.

[johnh]

with the right combo you can get the same economy as the DOD setup and a smaller cam as with a larger cam and canning the DOD...

Let me play devil's advocate for a moment....

If that was true then GM should fire all their Cam designers.

Why wouldn't GM do that from the start if they could get same/better mileage and more power? Especially since it would likely be cheaper (no DOD parts) and more reliable lifters = less warranty.

Why does the GXP get rated at 20 mpg then? It should be closer to the GT, since they theoretically can use a better cam...

Of course we all know GM doesn't always do what's best...:)

[Andy@Livernois]

Let me play devil's advocate for a moment....

If that was true then GM should fire all their Cam designers.

Why wouldn't GM do that from the start if they could get same/better mileage and more power? Especially since it would likely be cheaper (no DOD parts) and more reliable lifters = less warranty.

Why does the GXP get rated at 20 mpg then? It should be closer to the GT, since they theoretically can use a better cam...

Of course we all know GM doesn't always do what's best...:)

well, it's actually a good question. GM has to have silky smooth idle, where as a camshaft with more overlap will have a little bit of a lope to it... GM also needs to pass 50 state emissions, something that aftermarket companies don't have to worry about as much... GM also has to market the car to a wide range of people, where aftermarket manufacturers target a specific percentage of the group GM targets :D the people who want more power, some good sounds from the engine, and a faster car then GM supplied them with...

Most of the reason the GXP gets worse mileage is the gear ratio change, a larger displacement engine, and a cam that is bigger, but not big enough to play to the advantage of MPG...

The case I always use is Rick's car he used to own...

99 corvette, ls1 6-speed convertible. The car had longtubes and a CAI on it when he bought it and it averaged 27mpg on the highway... we installed our stage 1 heads, stage 1 cam, and 4.10 gears and on the same route he got 27mpg before he got 28 mpg after the mods, even though he made more power, and had a deeper set of gears...

it's all in having the right combo :D

[norm8332]

They just threw the DOD in there to increase the mileage enough to skip the guzzler tax. And to allow them to say "look at the great mileage"

They don't tell you that you still have to drive like Grandma to get anywhere near that mileage like any V8 car.

[Ktlplxm]

They just threw the DOD in there to increase the mileage enough to skip the guzzler tax. And to allow them to say "look at the great mileage"

They don't tell you that you still have to drive like Grandma to get anywhere near that mileage like any V8 car.

I don't know about grandma... I accelerate normally to 70-75 and set the cruise. I do drive like I have sense, and nothing to prove to the people around me, vs those that have to constantly reaffirm there place in the HP order of the world lol. I still don't see why the mileage is that much different in the GXP though. But then again, I never fully understood how an antiquated LT1 (supposedly soo much less efficient than LS1's and 2's) Impala weighing over 2 tons, could get better gas mileage than a GTO either, but it does happen. hahah

[johnh]

it's all in having the right combo

That's probably the best explanation.



They don't tell you that you still have to drive like Grandma to get anywhere near that mileage like any V8 car.

With the stock tune...I get much better results on MPG with DOD aggressively tuned.

Using the tune analogy...GM's tune on the G8 is dreadful (trans, limited DOD etc.) vs. even my "home-made" tune. I suppose its the same with cams too many trade offs--you can't have some woman who bought a G8 complaining that the car "wiggles" (lopes) at idle even if it has more power and more efficiency.

[Ed Curtis]

The technology and engineering is there for the successful use of DOD "and" VVT if you know how to apply it. To discount the effort to apply modern engineering into any car is akin to using point distributors and down draft carburetors just because the knowledge base is limited.

Companies like Comp and MAST are designing products that will allow for the retrofit VVT and DOD types of valvetrain, into non-DOD/VVT engines. All this effort so today's enthusiasts can obtain stand alone, computer controlled valvetrain systems. If these modern valvetrain features were obsolete, why invest the engineering and funds towards this direction? Just slap in the regular LS1 camshafts. Lots of time and money saved!

This reminds me of the whole SBF hydraulic roller mystery. How so many internet experts said you can't run a hydraulic roller camshaft over 6500 RPM. Yet, we were racing the stock, OEM Ford lifters to over 9000 RPM. Proper research and real engineering will always put to rest any theories or misinformation.

[bigwillys58]

Not really a hidden benefit. But you can get as much bang for your buck without spending the mony on a GXP by modding the G8. Unless you want bigger brakes and a stick, the G8 is the more economical choice. I'm at a higher HP than the GXP and under the cost of one. As for keeping the DOD with changing the cam....I wouldn't recommend it.
dang you beat me to it... agreed with him. i believe andy at livernois can set you up with a 440RWHP monster for $5300 (i can post this right? if not, sorry). combine that with the price of a showroom gt and its still cheaper than the gxp. unless you absolutely need the stick...

[Ktlplxm]

The technology and engineering is there for the successful use of DOD "and" VVT if you know how to apply it. To discount the effort to apply modern engineering into any car is akin to using point distributors and down draft carburetors just because the knowledge base is limited.

Companies like Comp and MAST are designing products that will allow for the retrofit VVT and DOD types of valvetrain, into non-DOD/VVT engines. All this effort so today's enthusiasts can obtain stand alone, computer controlled valvetrain systems. If these modern valvetrain features were obsolete, why invest the engineering and funds towards this direction? Just slap in the regular LS1 camshafts. Lots of time and money saved!

This reminds me of the whole SBF hydraulic roller mystery. How so many internet experts said you can't run a hydraulic roller camshaft over 6500 RPM. Yet, we were racing the stock, OEM Ford lifters to over 9000 RPM. Proper research and real engineering will always put to rest any theories or misinformation.

So are you saying it should be kept or not? If you are saying that the technology has the potential to be extremely reliable and powerful while maintaining efficiency, I can agree, but that doesn't necessarily advocate the retention of it at this moment. We now have extremely efficient MAF based management systems due primarily to the constant innovation of both the OE and aftermarket worlds; but it hasn't always been so. The first MAF driven TPI's were horrible. Cylinder deactivation found in modern vehicles is almost a seamless operation between 8 and 4 cylinders, whereas the early version found in Cadillacs was a nightmare. Hell, electronic fuel injection itself was not even that great when it first came out; 20 years later its wonderful. I know this seems like a useless diatribe, but my point is this: not everyone wants or needs to wait around for it all to be "figured out", or to constantly be on the leading front of development. For those who do want to pioneer these areas (VVT, DOD, etc), KUDOS, we salute their patience and perseverance. But, to the rest of us who want to maximize what we have, without the added hassle of these innovations, non DOD is the way to go. After all, not all of us can afford the trial and error segment of research and development, and if the tech does get sorted suitably while we own our vehicles.... we can put it back on.

[norm8332]

I don't know about grandma... I accelerate normally to 70-75 and set the cruise. I do drive like I have sense, and nothing to prove to the people around me, vs those that have to constantly reaffirm there place in the HP order of the world lol. I still don't see why the mileage is that much different in the GXP though. But then again, I never fully understood how an antiquated LT1 (supposedly soo much less efficient than LS1's and 2's) Impala weighing over 2 tons, could get better gas mileage than a GTO either, but it does happen. hahah

BTW, Some people like to accelerate briskly because they enjoy it. If someone wanted to show off would they have got a G8?

Hell, I drive like a race car driver all the time, but I know how to do it without any tickets in 10 years and not even a fender bender in 20. We are not all kids with these cars.


On topic: I ditched the DOD with a tune and have never looked back.

[Ktlplxm]

BTW, Some people like to accelerate briskly because they enjoy it. If someone wanted to show off would they have got a G8?

Hell, I drive like a race car driver all the time, but I know how to do it without any tickets in 10 years and not even a fender bender in 20. We are not all kids with these cars.

I must have missed where I said anything about age...
Oh, no, I did not miss it because I never said it. Someone else first used an age reference with "grand ma" and then again with "kid". Responsible driving is not a byproduct of age, but rather maturity. Saying that you have to drive like a grandma to get the recommended mileage would infer that one had to accelerate slowly to reach, if ever, the speed limit. But of course, since you drive like a race car driver, you know 90% of the time is spent conservatively waiting for the right moment to get aggressive. Oh, and congratulations for the lack of citations, and hopefully you can have another 20 without a fender bender.. of course driver skill only plays so much of a part, the other half is being lucky enough that no one runs into us while we are sitting still.

[norm8332]

Whatever, I'm not arguing with an cocky smart-ass. :nah: The HID gave you up.

Done.

[Ktlplxm]

:cheers:

[Andy@Livernois]

The technology and engineering is there for the successful use of DOD "and" VVT if you know how to apply it. To discount the effort to apply modern engineering into any car is akin to using point distributors and down draft carburetors just because the knowledge base is limited.

Companies like Comp and MAST are designing products that will allow for the retrofit VVT and DOD types of valvetrain, into non-DOD/VVT engines. All this effort so today's enthusiasts can obtain stand alone, computer controlled valvetrain systems. If these modern valvetrain features were obsolete, why invest the engineering and funds towards this direction? Just slap in the regular LS1 camshafts. Lots of time and money saved!

This reminds me of the whole SBF hydraulic roller mystery. How so many internet experts said you can't run a hydraulic roller camshaft over 6500 RPM. Yet, we were racing the stock, OEM Ford lifters to over 9000 RPM. Proper research and real engineering will always put to rest any theories or misinformation.


While we use and respect companies such as those, it doesn't mean they are right... Comp to this day still denies an issue with the VCT system in the ford 3-valve, their explanation to the limiter system is to prevent a rare occurrence... I can tell you EVERY 3-valve car we have fitted with cams has had the vct fail. It's not a rare issue at all. We have even seen it fail on the cars equipped with cams Comp and Ford advertise as not needing heavier valve springs, or phaser modifications... You would be surprised how little R+D goes on with most aftermarket companies...

As I have stated numerous times before, the stock DOD system gets loud and clattery even on the stock engine... how do you think it's going to enjoy sustained increased valvetrain load? plus the DOD system starves the cam bearings with oil from our testing @ higher RPM... Paul's car already had visible copper showing on every cam bearing after only 5100 miles with only a ~6200 rev limit... it will wipe them out faster with a higher limit...

We do quite a bit of engineering work along with OE manufacturers, so we know alot of inside info on alot of current and future powertrain programs. Flat out, there is a reason GM did what it did on both the VVT and the DOD system...

If you want to push this system with your car, go for it... Will I, someone that has to deal with a customer before, during, and after install recommend retaining DOD with a larger cam? Hell no, they are putting their trust in me to advise them on the best route for their beloved car... I could not in good conscious recommend retaining a system I have witnessed failures with when pushed past its engineered limit...

As far as MAST goes, they do good work, I have known the guys there for a couple years, but most of their engine kits get swapped into street rods, not cars people race everytime they drive it...

[norm8332]

Paul's car already had visible copper showing on every cam bearing after only 5100 miles with only a ~6200 rev limit... it will wipe them out faster with a higher limit...


Andy, is this happening with the stock setup with just the higher rev limit? What about tunes that are raising the rev limit that everyone is doing?

Thanks.

[Ed Curtis]

The point is, the option for the G8GT enthusiast to retain or replace the DOD system is what has been accomplished. If the time and effort we have used to perfect these products frustrates many others, there's not much I can say. We prefer to lead, rather than follow.

I've worked as the senior engineer for companies such as Allied Signal and others who were contracted to design, develop and deliver results on a lot of special projects for the auto industry. As such, I don't fear looking at projects such as the DOD valvetrain from a broader perspective. I guess you just can't take the mechanical engineer out of me, even when I no longer work for these big companies...:p

No matter, New Era Performance Parts has both options available to the GM enthusiasts. We're going to work on a few more developments once the new project 2010 Camaro starts up. Stay tuned as we look to the future of LSx performance and racing...
:woohoo:

[ChipC]

... There is even a reason the lobes are even less aggressive on the cylinders that have the special lifters compared to the normal lifters...

Andy,

The DOD lobes have more lift, but do they have a different ramp rate, etc.? I always thought of the DOD lobes as being more aggressive due to the higher lift, but I haven't seen the overall lobe profile and now maybe my thinking was in error.

Chip

[Andy@Livernois]

Andy,

The DOD lobes have more lift, but do they have a different ramp rate, etc.? I always thought of the DOD lobes as being more aggressive due to the higher lift, but I haven't seen the overall lobe profile and now maybe my thinking was in error.

Chip

From all of the information I have at hand it has a more gradual ramp on the DOD lobes...


The point is, the option for the G8GT enthusiast to retain or replace the DOD system is what has been accomplished. If the time and effort we have used to perfect these products frustrates many others, there's not much I can say. We prefer to lead, rather than follow.

I've worked as the senior engineer for companies such as Allied Signal and others who were contracted to design, develop and deliver results on a lot of special projects for the auto industry. As such, I don't fear looking at projects such as the DOD valvetrain from a broader perspective. I guess you just can't take the mechanical engineer out of me, even when I no longer work for these big companies...:p

No matter, New Era Performance Parts has both options available to the GM enthusiasts. We're going to work on a few more developments once the new project 2010 Camaro starts up. Stay tuned as we look to the future of LSx performance and racing...
:woohoo:

GM must have their reasoning for running smaller cams and lighter springs with this system... period. If it was "ok" to do so, why doesn't the L99 have the same cam as the LS3? why did GM put such a small cam in the L76 when an LS2 cam, or even an LS1 sized cam would have worked well?

Now I can see the appeal in retaining VVT... but retaining DOD just really isn't that appealing... The VVT system can increase power, torque, fuel economy, and idle quality/driveability, but the DOD system doesn't really benefit the enthusiast... And regardless of who is doing these things, slapping a few camshafts in DOD equipped cars and saying "hey, it hasn't failed yet" should not appease the engineer in you... Look how long GM did R+D on this system for... it started, what, 1999? so if finally comes around in fwd form in 2004? so thats a minimum of 4 years R+D, combined with thousands of dedicated test engines, pilot cars, revisions, etc... just to finally decide to run as light of springs as possible, and run a small cam with it...

I am certain GM did routine oil analisys, bearing inspections, total engine teardowns, and durability tests before reaching this conclusion. So like I said, slapping in a camshaft in a handful of cars and saying its ok after maybe 2 years (3 tops) doesn't convince me. Call me a fear mongerer, call me a skeptic. You won't see me betting someone else's engine/car to test it out... this is why we have company development cars and engine dynos with company owned engines.


Andy, is this happening with the stock setup with just the higher rev limit? What about tunes that are raising the rev limit that everyone is doing?

Thanks.

So far the DOD equipped cars with a higher rev limiter have been the only cars we have seen with this trouble... The stock DOD oiling system diverts oilflow to the lifters instead of the camshaft, and the lifters need a ton of oil (hence the higher volume oil pump and huge oil pan) so when you raise the limiter too far (which it will vary from engine to engine on what is too far) while retaining the DOD lifters it can starve the cam bearings (and possibly other components as well). this is just another reason to ditch this system...

[Grantski Barney]

This is a very enlightening thread. I am divided between this and Rambo: First Blood Part 2. It sounds like DOD can be good if they worked on it some more. I also think I will be getting a cam installed (non DOD) once I get my car. How much is the labor on something like that?

[norm8332]

Looks like a Non-DOD cam is in my future. Thanks for the info.

[Mike@NewEra]

Andy, you have a pm.

[johnh]

Paul's car already had visible copper showing on every cam bearing after only 5100 miles with only a ~6200 rev limit... it will wipe them out faster with a higher limit...

Hmm Good to know. 6200 is only 200 rpm over stock. Seems like a pretty tight tolerance if 200 rpm makes that kind of difference.

So have you seen this on more than one car Andy? Anyone else seen this?

[Andy@Livernois]

Hmm Good to know. 6200 is only 200 rpm over stock. Seems like a pretty tight tolerance if 200 rpm makes that kind of difference.

So have you seen this on more than one car Andy? Anyone else seen this?

2 cars, and numerous engines with this system so far...