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99dart
12-09-2010, 03:47 AM
To the cam an SCT can tune? Lift, duration?

BryanRT360
12-09-2010, 03:50 AM
Dave D has a huge cam with an sct tune. think its over 250 duration. Of course we have no idea how it actually runs..

dakfink
12-09-2010, 04:22 AM
This would be a Hemifever question. But I don't see any real limits to it.

I know lift wouldn't be a factory.

Duration alone shouldn't be??

It's really a combination of Duration and your resulting Overlap that may be the issue.

What has made Cams an issue especially with the stock PCM is the unsteady or too-low MAP (vacuum) signal, when you have larger duration and a low LSA which gives a lot of Overlap.

Now you can increase your LSA (decreasing overlap) to smooth out the idle. Which in turn you loose some top-end but get a broader power band. Where this was an issue with the stock pcm (No SCT) is that you now can idle fine but the PCM isn't tuned to give extra fuel/spark where needed.

So, Your Duration and LSA (or overlap, whcih ever way you like to look at it) would be your 2 biggest factors.

Again this would be something Hemifever would have to answer.

I have no clue if SCT has a way to satisfy the PCM when seeing a radicaly varibale MAP signal.

nevr2fast01
02-08-2011, 01:20 AM
^^ what he said, you just gotta remember you cant run over 512 lift on stock pistons or else you might drop the valves into the pistons

BryanRT360
02-08-2011, 01:32 AM
^^ what he said, you just gotta remember you cant run over 512 lift on stock pistons or else you might drop the valves into the pistons

I'm running .580/.569 lift with stock pistons. PTV is not a issue with our motors. The problem to retainer to valve seal.

nevr2fast01
02-08-2011, 01:34 AM
no shit haha everyone on the dakota-durango.com says no way over 512 without reliefs
time to call comp cams.....

2k1AmberR/T
02-08-2011, 01:34 AM
I thought you could go higher as long as you used .600 springs.
Planning on going .544 with .600 springs and flat tops with valve reliefs. I swear guys are running .544 on stock pistons. I think Bryan was.

Someone please advise.

I've got a .544 lift cam with stock pistons. No issues. 226* duration. Don't forget duration plays a part in it as well.

BryanRT360
02-08-2011, 01:35 AM
no shit haha everyone on the dakota-durango.com says no way over 512 without reliefs
time to call comp cams.....

maybe your thinking about the 318

Branx5.9
02-08-2011, 01:38 AM
I don't forsee any limits with it either, I have been discussing with Shawn about tuning for the cam that i'll be running in my 360. 230/236@ .50, .571/.574 lift on a 110 lsa

Here are a couple of his replies:

I'd probably lean towards the 24's. If the 21's are a really good price you could possibly try those first. And just a comment on the 230 cam. Once you get to that duration it wreaks havoc on the front o2 sensors and it'll have to be tuned and run all the time in open loop. It'll have some part throttle fueling quirks running in open loop so I just wanted to give you a heads up.
it's tough getting it completely dialed in running in open loop. We can do a closed loop tune that may pass emissions if you have to worry about that. The problem with closed loop is the a/f will sway between rich and lean because the o2's can't manage the cam overlap and there isn't a way to manipulate the o2 signal delays. But it may struggle even in open loop with rich conditions letting off the throttle or doing quick stabs but that's about it. Dialing it in takes a little extra effort but I've done quite a few.

Five9Dak
02-08-2011, 02:02 AM
I think this is a Chris @ PIE question. There will be a point where the factory style acceleration enrichment simply can't be tuned with the poor MAP signal quality at idle. So idle speed will have to go up, and off idle response/transient response will suffer. Most big cam SCT setups are probably already compromises and the owners don't know any better. I don't know where the "limit" is, it's probably more of a continum.

Aftermarket EMS will absolutely still run large cams better, but if you have enough converter to hide it, it's probably still not worth it for NA applications.

Adobedude
02-08-2011, 02:03 AM
I don't forsee any limits with it either, I have been discussing with Shawn about tuning for the cam that i'll be running in my 360. 230/236@ .50, .571/.574 lift on a 110 lsa

Here are a couple of his replies:

I'd probably lean towards the 24's. If the 21's are a really good price you could possibly try those first. And just a comment on the 230 cam. Once you get to that duration it wreaks havoc on the front o2 sensors and it'll have to be tuned and run all the time in open loop. It'll have some part throttle fueling quirks running in open loop so I just wanted to give you a heads up.
it's tough getting it completely dialed in running in open loop. We can do a closed loop tune that may pass emissions if you have to worry about that. The problem with closed loop is the a/f will sway between rich and lean because the o2's can't manage the cam overlap and there isn't a way to manipulate the o2 signal delays. But it may struggle even in open loop with rich conditions letting off the throttle or doing quick stabs but that's about it. Dialing it in takes a little extra effort but I've done quite a few.

He dialed in my 236/242 cam...On the 24's he still had to trim fuel. I don't have to pass emissions, but like he says, it does go crazy rich at the end of a run after I let off.

bad360rt
02-08-2011, 02:28 AM
My cam is 262/270 (@ .050) .602/.585 108lsa and Sean was able to get it to fire up on the first try. It was idling high, but that's to be expecting with a big cam. Probably could have got the idle down a bit more with some more tweaking.

Adobedude
02-08-2011, 02:41 AM
My cam is 262/270 (@ .050) .602/.585 108lsa and Sean was able to get it to fire up on the first try. It was idling high, but that's to be expecting with a big cam. Probably could have got the idle down a bit more with some more tweaking.

pfffffft.

That's a baby cam Mr Carb....:jester:

dakfink
02-08-2011, 03:23 AM
My cam is 262/270 (@ .050) .602/.585 108lsa and Sean was able to get it to fire up on the first try. It was idling high, but that's to be expecting with a big cam. Probably could have got the idle down a bit more with some more tweaking.

What were you Idling at?

I think some of these guys think they are going to put a BIG cam in and still idle at factory settings around 700 rpms!!

More dusration and more overlap and less Lsa is going to require a Higher Idle speed.

bad360rt
02-08-2011, 05:01 PM
What were you Idling at?

I think some of these guys think they are going to put a BIG cam in and still idle at factory settings around 700 rpms!!

More dusration and more overlap and less Lsa is going to require a Higher Idle speed.

1400rpm on the initial tune, never tweaked it past that. Could probably have gotten it down a lil bit. I'm gonna run a carb for now, might go back to EFI later.

http://www.youtube.com/watch?v=GvW7NpiaVrs

Hugh Jassole
02-08-2011, 05:32 PM
I thought you could go higher as long as you used .600 springs.
Planning on going .544 with .600 springs and flat tops with valve reliefs. I swear guys are running .544 on stock pistons. I think Bryan was.

Someone please advise.

I am too

Adobedude
02-08-2011, 06:20 PM
I am too

.548/.547 on stock pistons

Sick 660r
02-08-2011, 07:57 PM
no shit haha everyone on the dakota-durango.com says no way over 512 without reliefs
time to call comp cams.....

Thats your problem

KTK00R/T
02-08-2011, 08:00 PM
Thats your problem

:jester:

Sick 660r
02-08-2011, 09:14 PM
:jester:

I feel like this place is becoming infested with dak-dur people.

Five9Dak
02-09-2011, 12:17 AM
I feel like this place is becoming infested with dak-dur people.

There's a few new members lately who can't complete a sentence, or listen to a reply that answers their question.

Adobedude
02-09-2011, 12:30 AM
There's a few new members lately who can't complete a sentence, or listen to a reply that answers their question.

adn tay pots the sainme ting own everer thrude lol lol

nevr2fast01
02-09-2011, 02:16 AM
ok i will admit i am not the cam guru, or a noob just because my join date. i've been into dakotas for over 10 years and have had my share of r/t's and am more school'd in nitrous and boost and suspension mods so next time i'll keep my mouth shut and leave it to the veterans

jweltch
02-09-2011, 03:58 AM
Pfft...

These guys are pussies.

Go to www.racemagnum.com and ask a dumb question and you'll thank the people here for being the dicks they are.

:D

KTK00R/T
02-09-2011, 01:05 PM
Pfft...

These guys are pussies.

Go to www.racemagnum.com and ask a dumb question and you'll thank the people here for being the dicks they are.

:D



haha..