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Twins and cam

21K views 36 replies 7 participants last post by  fish2keel 
#1 ·
Hey guys,

So I'm building up my 6.1 and have my twin 68s but am unsure of the cam. I love the lope of the srt max but im open to ideas. This my first gen 3 hemi(I'm used to Ford's and 440s). I want that classic rumble lope. Any help with cam choice would be great!
 
#2 ·
Call and talk to the cam manufacturer of your choice. The technical guys can help you choose the profile that will both work with your twins and provide the sound you are looking for.
 
#5 ·
You should talk to Erik @BFNY PERFORMANCE. 440-787-7235
 
#7 ·
Fyi, most of your lope in a cam comes from valve overlap. A turbo cam typically doesn't have the overlap of an NA or blower car, so you might be a bit disappointed in that respect. The 6.1 factory cam is a good turbo cam to a pretty high HP level. In my case I was making close to 800HP on a factory 6.1 engine at only 14psi. Personally I'm a cheap bastard so I would go with a factory cam if I was 800HP or less, but that's just me...
 
#9 ·
Custom Turbo - Take 3

When does 300 + 25.3 == 6.5?

Last year was the it for the factory engine, new engine build should be complete any day. It's a max effort turbo purpose built engine, no details spared on the build. I will post something soon when I get the engine in the shop. Will still run the twin 67's on E85 this year, but will go to single 88 next year on meth. Good luck with your build.
 
#11 ·
I ran factory pcm and tuned with Diablo CMR through last year. This year the car is stripped down and plan to go with ProEFI. Engine did fantastic, went 10.33 on it and could have gone faster if the suspension was up to the task, absolutely no issues. Ran like a top when I pulled it out. Sitting on a stand in the shop waiting for me to put it up for sale.
 
#13 ·
Yes, I am selling it all. I planned to try to sell it all together initially. Complete car harness, tcm, pcm(setup for non nag1 trans), evic, security including key and modules, accelerator pedal, all body modules, front and rear fuse modules, EVERYTHING.
 
#16 ·
In my opinion, the only limit would be when you get to a point where you need to drive more powerful coils or low impedance injectors(that's where I am at). That's probably when you get to about 1500hp.
There are the part throttle issues, but if the tuner knows what he is doing, this should not be a problem. Other problems might be to get everything to work without lights on the evic. Might take a chrysler flash device get all of the pretty lights to go off. Mine was fine until I took all of the air bags and seat sensors out then I just had to live with the lights on the dash.
 
#17 ·
Whats size turbine / AR are you running with those 68's? prob more than half of the cam design for the turbo helps or doesn't with spool. I have twin 6266 on a 392ci, so I will have little trouble spooling them up so not a lot was done to help spool in my cam design. The other side of the envelope is maximizing turbo efficiency, turbos do great already on pulling on the exhaust side of the motor since they are exhaust driven, so most good turbo cam designs lean towards the intake side to help get more air into the cylinders. A stock 6.1L sized motor with roughly .600 lift will prob want to be between 225-230 on the intake side, then the rest just starts to fall into place. You want to limit overlap on a boosted car to get a good cylinder fill and good cylinder pressure without bleeding off boost with too much overlap. Most of the time youll end up in the 235-240 range for exhaust side duration. Keep ICL around 116-118 and grind a few degrees advance in it so you don't have to do so much VVT tuning and will limit the crazy chop that will drive your tuner mad.
 
#19 ·
Confused, thought you had a 6.1L? Cant use a hellcat cam (or any VVT cam) in that motor, doesn't swap over, 6.1L is a non VVT motor.

And yes Hellcat cam is built for SUPERCHARGER boost, not turbo, and was designed to meet emissions standards, there is more power to be made with a more aggressive cam.
 
#21 ·
Once you see the specs, you'll understand the main power comes from the VVT tuning to compensate for the smallish cam.

215/221 duration
.561/.551 lift
120.5 LSA

In the world of custom grind cams, that is pretty dang small. There is zero "rumble" with the factory hellcat cam.

You would almost be better off going with a factory 6.4L cam; the hellcat cam has less intake lift and adds 20 degrees of duration on the exhaust side to help with scavenging and making the blower more efficient, something not needed on a turbo car.
 
#23 ·
No worse or better than a hellcat cam.

You need to check piston to valve clearance and will need cam phaser limiter or lock.
 
#25 ·
Agreed, though there aren't many turbo builds in general on any of those. But mostly you don't see it because if you spend a good chunk on a forged motor most people also spend the money on a custom cam.

I would recommend stopping referring to anything 6.1L; the non VVT 6.1L is unique and the cam cannot be used in anything but a non VVT motor (early 5.7L and 6.1L).

So your choices to swap around stock cams are late 5.7L, 6.4L, or 6.2L.
 
#27 ·
Cam phaser limiter will limit the movement, cam phaser lock will eliminate any movement, there are both available. Which one you need will be determined by the cam design.

There are a set number of movements the ECU does that I believe the tuners have trouble controlling, so they prefer to mechanically limit the cam from coming close to contacting. When you go big enough on the cam size, there is a little if ANY movement that wouldn't result in PTV contact so that's when it needs to be locked. I was surprised when A2Speed told me to lock my cam, but it came down to the piston design.
 
#30 ·
No, I wouldn't do it. The exhaust side is a different install height on the 6.1L springs than the eagle stock springs, so much so youd be running a big shim to make it work. Intake side would work with a lesser shim, but personally I would just spend the dough on a nice set of PSI springs.

This is the hard part about doing a cam swap, you basically end up needing to do just about everything needed to run a monster cam no matter if you stick with a close to or stock cam from another motor.
 
#32 ·
what year eagle is your current motor? Just checking and looks like Stu used 6.1L intake springs for cams up to .340 lobe lift with shims, but that was on 2012+ eagle heads.
 
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