If you are considering new cam, here's some data

[Atppilot]

During the last two days I have driven my new Gen III build to work (approx. 50 miles) at both city and hwy speeds (80mph). The car drives nice at 80mph in 5th turning 2300rpm. Bring her down to city speeds 30-40mph and you cannot cruise around less that 2000rpm as the car wants to go into reversion. I have been working with Dan and Chris at DC performance and as busy as they are, they have always been there to take the time to explain and assist me during the tuning process – hell; Chris even emailed me a tune at 10pm LA time. First class these boys! Here are my specs:
LCA 114 plus 4, 232/236 Dur at .050 .601/.606 valve lift on 1.7 Rollers Manley Valves SS valves 2.02 and 1.60
Roller rocker arms (prepare for more sewing machine noise)
Isky springs
Comp Cam push rods
Greg Good heads
AB Quality wires
LPW Breathers
If you are a true motor head who enjoys that lopey idle at the stop light and banging gears, it’s for you. If you are not and really enjoy cruising around the city at less than 2000rpm, a big cam is not for you and you should consider the twin turbo or supercharger route
Larger cams with more overlap creates the following:
* Smell of un-burnt gasses at idle as a result of both intake and exhaust open at the same time.
* You will never get the “reversion” completely out, although Chris at DC Performance has a few tricks to minimize.
* You will lose your 5th gear(or change rear ratio) because you will need to keep the exhaust pressures low to allow flow of the gasses, i.e. throttle. When reducing the throttle in 5th at such a low rpm (higher pressure), revision will reappear.
* You will have to learn how to drive the car all over again – it’s a race car now, not a Sunday afternoon cruiser in 4th gear at 40mph turning 1800rpm – it will have a tendency to surge(go into reversion).
* You can advance the cam a couple of more degrees(installed) and reduce reversion but you will increase cylinder heads pressures and come closer to piston to valve clearance issue as well as in create possible detonation.
Considering all this....Do I like my new build – HELL YES!!!!!!!This thing is a beast!!!!

 

[Darbgnik]

This is the first post I've read on livability of a big power motor. Thanks for being candid. I'm sure some wouldn't as to them it would be like admitting they didn't get what they wanted.

 

[plumcrazy]

IMO, there is no possible way a tuner can tune from another state. id bet if you gave a tuner with the skills of DC a chance to tune in person for a week in different situations, it can be tuned out. tuning is not just on a dyno......

doing it over the phone isnt going to work and not a fair assessment and tuning with just an SCT is also not optimal in some cases. this is probably one of them

my cam is no quite that big but its 100% streetable

 

[Atppilot]

Yes Plum I agree. I just wanted Chris to make sure I wasn't too lean when I drove my car to Titan Motorsports for a dyno tune. I am in the ballpark based on numerous cars before me. Dyno tune next monday.
One other thing to remember is that the Viper motor is a big low rpm running machine. Overlap is not your drivabilty friend at low rpms.

 

[ViperTony]

I think Tim and I have the same cam. The big lopey cam rocking the Viper at idle is...bliss. The sound of Armageddon coming from the exhaust is euphoria. At WOT...all I can say is that I drive around with a ******.

I don't know what 'reversion' means? But I don't have any surging going on. I haven't tuned yet but logging my AFR and OBDII diagnostics it seems that the stock PCM is handling the heads/cam just fine.

Tim's spot on in that now it's much more of a race car...and that's how it should be.

 

[351carlo]

Great writeup but there shouldn't be any surging or reversion on a cam of that size. It's definitely a matter of giving it to a tuner with some experience in person. We've run into numerous occassions where we had the same cam in two different cars and the tunes had to be tweaked to prevent surging; these cams were often 24x/25x in size as well on a similar LSA.

Good luck, I'm sure it'll be great! Want to see some graphs too and trap speeds. Thanks again and happy motoring.

Edit: Any tuners mentioned in this thread would be able to straighten it out in person I'm quite certain. It's very common to see the surging of that nature with a mid sized cam when the tune hasn't been gone through thoroughly in person.

 

[plumcrazy]

DC or any other top tuner would be hooking all kinds of tuning equipment to the car and driving it around in various conditions for a few days or in some case.....weeks. then putting it on a dyno for a number.

lol, my car looked like a syborg with all the stuff doug had hooked up to it. he tuned it in every possible way except snow. he logged/tuned in the rain, night, traffic, slow driving, WOT, cooler weather, stupid hot and humid of south florida. then finally put it on a dyno for a final number to make me happy.

get that beast tuned properly and then let us know how driveability is... this thread was a little misleading at first.

 

[Atppilot]

Thanks again Plum. Don't get me wrong here, I'm not bumping my head on the steering wheel during low rpm driving, but this is not a stock cammed Viper and it certainly does not drive like one.

 

[plumcrazy]

i bet it doesnt

good for you !

 

[Viper Grenade]

I may have missed it. But what rwhp are you making? Do you think it will pick up much after a tune?

 

[Atppilot]

Honestly not sure, but I was thinking 600ish. I will post stats after dyno next week.

 

[ViperTony]

Tim, can you post up a pic of your LPW breathers? Thanks.

 

[dave6666]

As a side note for those wanting the lumpy cam'd idle but can't afford a build or don't want their car down that long or whatever, just switch to Wal-Mart 87 gas.

 

[vpower01]

As a side note for those wanting the lumpy cam'd idle but can't afford a build or don't want their car down that long or whatever, just switch to Wal-Mart 87 gas.

love these threads!

 

[martyb]

The cam I had in my RT/10 was almost identical, I could cruise down the highway in 6th at 1200rpm no issues. I agree with Plum, I think if you get a good tuner to work on the car in person it can be made much better.

Congrats on the build.

marty

 

[Greg Good Cylinder Heads]

I think Tim and I have the same cam.

Yes, Same exact cam, and degreed exactly the same. *Should* have the same drivability, but some cars are different, as a lot of us have seen.


I'm curious if it does better after it is street tuned with the tuner sitting in the passernger seat. I think it will.

 

[banton]

Nice set-up, congrats and enjoy. A GG heads/cam equipted car is fun

 

[Greg Good Cylinder Heads]

This is the same cam that's in your car too!

 

[banton]

This is the same cam that's in your car too!

Except I got mine about 3 years ago....an early adopter, so to speak

 

[dipapa]

During the last two days I have driven my new Gen III build to work (approx. 50 miles) at both city and hwy speeds (80mph). The car drives nice at 80mph in 5th turning 2300rpm. Bring her down to city speeds 30-40mph and you cannot cruise around less that 2000rpm as the car wants to go into reversion. I have been working with Dan and Chris at DC performance and as busy as they are, they have always been there to take the time to explain and assist me during the tuning process – hell; Chris even emailed me a tune at 10pm LA time. First class these boys! Here are my specs:
LCA 114 plus 4, 232/236 Dur at .050 .601/.606 valve lift on 1.7 Rollers Manley Valves SS valves 2.02 and 1.60
Roller rocker arms (prepare for more sewing machine noise)
Isky springs
Comp Cam push rods
Greg Good heads
AB Quality wires
LPW Breathers
If you are a true motor head who enjoys that lopey idle at the stop light and banging gears, it’s for you. If you are not and really enjoy cruising around the city at less than 2000rpm, a big cam is not for you and you should consider the twin turbo or supercharger route
Larger cams with more overlap creates the following:
* Smell of un-burnt gasses at idle as a result of both intake and exhaust open at the same time.
* You will never get the “reversion” completely out, although Chris at DC Performance has a few tricks to minimize.
* You will lose your 5th gear(or change rear ratio) because you will need to keep the exhaust pressures low to allow flow of the gasses, i.e. throttle. When reducing the throttle in 5th at such a low rpm (higher pressure), revision will reappear.
* You will have to learn how to drive the car all over again – it’s a race car now, not a Sunday afternoon cruiser in 4th gear at 40mph turning 1800rpm – it will have a tendency to surge(go into reversion).
* You can advance the cam a couple of more degrees(installed) and reduce reversion but you will increase cylinder heads pressures and come closer to piston to valve clearance issue as well as in create possible detonation.
Considering all this....Do I like my new build – HELL YES!!!!!!!This thing is a beast!!!!

Thats a good description.

I swear thats the same GG cam I got too...and those GG heads..talk about breathing.

The car pulls better now in 5th gear and at lower rpm than before in 4th gear at higher rpms when I had every bolt on the all motor.

Todd @ A&C did an incredible job setting the valvetrain and T&D rockers to be relatively quite and smooth and tuned this motor very thoroughly to very high levels of performance.


With the heads & cam, built motor and SCT tune the car bucks allot too in city driving in lower gears & lower rpm but i have to feather the throtle pedal or lift clutch to suppress it...But the bucking just makes the car feel like its so "ready to romp" instantly. Plus I avoid local driving...its an open road machine at least i like to drive it for that purpose.

Yeah...car smells of exhaust but thats the compromise on N/A big performance. Its ok.

I have been to several weekend car shows in the San Francsco bay area and when this heads & cam setup rolls in to the lot...it commnads attention. I was told it also doesnt have the UPS truck sound anymore as well.

It maintains a stable idle incredibly well.

At WOT the explosion of sound is incredible so i decided to use the stock mufflers, too tone it down just a bit, minus Xover and use 1 3/4 AR headers with cat delete setup.

GG also did real nice porting deep into the intake runners and to match his intake side of the heads.

I really like it. No need to ever look at anything else anymore.

 

[GTS Bruce]

Doesn't seem like a problem to me. I know how to shift and select the proper gear. GTS Bruce

 

[Twister]

Nice write up. apreciated

 

[viperbilliam]

Dipapa - how are you going to get this past emission checkup time?

Reversion - undesirable side effect of overlap - when both the intake and exhaust valves are open at the same time - too much overlap allows exhaust gases to contaminate the intake charge at lower rpms, reducing power (torque) and gas mileage at these speeds. Of course in the other direction, unburned gases (intake) goes into the exhaust.

 

[Atppilot]

Here you go Tony.
The LPW breather are positive lock design. They come with a check ball in them that you have to remove if you are running atmospheric. They have internal baffles and a removable/cleanable filter. I installed the external filter as an added layer of protection. Also, I installed them fore and aft because I wasn't sure if the left one(facing) was going to clear the environmental system plenum. Personally, I think it looks pretty trick like this.

You must be registered for see images attach

 

[Camfab]

Dipapa - how are you going to get this past emission checkup time?

Just make sure you put the factory cats back on it for emissions testing.

 

[plumcrazy]

maybe in cali the cats are needed to pass emissions but not all states. (other than visual inspection of them)

 

[viperbilliam]

Just make sure you put the factory cats back on it for emissions testing.

Too much trouble just for emission checks

 

[MTGTS]

Are you going back to Titan??? I live 5 min. from them but don't take my car to them for work. They are very good @ what they do which is Supra's and imports. They really don't specialize in the Viper @ all. I take my car to Larry Macedo and that's where I would go if I was you. He knows what he's doing when it comes to Vipers