black_c7

Hey guys

i have a c7 corvette with built engine and im going to twin turbo it, wanted to ask what is the cam options and is it gonna be much better to go custom cam over the current cam i have( stage 2 supercharged cam from btr) 225-240 635 625 116,

would a custom cam have much more advantage?

Chiselchst

...for $25 you could have Pat G answer that question with his own recommendation...

Unreal

Wrong section of forum. Depends on what you want out of it. Maybe, maybe not. Pat G is excellent at specing cams, but so is BTR and many others. Find one you like/trust and pay them to spec a cam.

black_c7

I know its not the c7 section i was asking about cams in general, because the c7 platform doesn’t have as much twin turbo setups as the c6 platform.

Shortpersonbk

In these situations you should just call BTR since you already have a cam from them and ask. IF they say use something else buy what ever they say and keep it moving. So many good venders can spec a cam many members are smart enough to guess if it will be good enough but might as well ask the guys who do it all day and sold you the last cam.

black_c7

Any suggestions?

FourG63 97GST

Cam selection is so personal. I ended up with a custom grind personally, the off the shelf stuff is pretty generic to fit the masses. but may not dial in what you want out of it, for the turbos you're running.
but def get rid of the supercharger cam, turbo cams uses a whole different logic, one of it's main purposes is managing back pressure, while an n/a or supercharged cam spec, will still be focuses on scavenging.

TurboLX

Less is often more with turbo cam selection. You can go backwards easily if you have a street car setup running low to moderate boost levels. In many cases, it's more efficient to just turn up the boost a couple more psi on the stock cam. But if you're doing a big power combo that doesn't care about low end response or emissions, many of the common suggestions you'll get here (or from vendors here) will probably get you where you want at the end of the drag strip.

black_c7

im definitely going with a custom cam, but dont know who to let spec me the right cam

black_c7

I want a custom cam that will help wake up the car a little down low

TurboLX

What do you consider "down low"? To me, as an OEM calibrator, that means ~1300rpm. To most people here, it's probably something different. The wide lobe separation and minimal overlap of a stock cam are actually very good low end response with a turbo. Your biggest gains actually come from harnessing exhaust energy through a combination of proper A/R sizing, pipe diameter and pressure drops along with calibrating to maximize exhaust energy to spool the turbo down low. (Increase EGT and velocity with low spark and an only slightly rich mixture) Phasing the stock cam on an LT1/4 can also have some benefits over an aftermarket cam that gets locked in one place.

Since it sounds like you're committed to choosing something special for your combo, I'd just recommend going with something smaller than you think you "need". Large durations (especially on the exhaust side) will reduce port velocity at low engine speed, so don't get sucked into something with 230+ duration if you want to optimize low end transient response. I run a very mild cam on my street LS3 TT car, 222/218-117 for example. It was just enough to wake it up without ruining emissions (I still have cats) or spooling with a pair of GT3076r's and 0.86 A/r housings. Proper recalibration of the VVE model (including the cam phasing and then the torque model on your LTx) is still absolutely required if you want good drive quality too. It will not be a two hour tuning event for you if it's being done right.

black_c7

the car doesn’t have a stock cam, it already have a btr stage 2 supercharger cam 224 240 635 624 116, and the phaser is locked so it cant be played in the tune, i have even a smaller ar size than what you have 0.82 and still the car doesn’t spool fast, im thinking because the turbo is too big for the power it making and because the small 377 ci , the turbo is a 6767

TurboLX

240* exhaust duration is not helping your low RPM spooling. Your stock cam would likely spool faster down low because it would have a higher port velocity at the same total mass flow rate. A 6.2L high compression engine should not have too much trouble spooling a single 67mm turbo with an 0.82 hot side as long as the cam is reasonable and everything is calibrated correctly. 240* is not what I would consider ideal for your scenario, so I'm back to recommending something much milder for you.

black_c7

what about twin 6767 lol,

TurboLX

D'oh, I should have noticed that in the thread title, no? Splitting the exhaust energy across TWO turbos only strengthens the argument for high temperature and port velocity (which come from a smaller cam, relatively speaking) if you want to improve low end response. But at some point, you may be limited by the engine and turbo hardware selection. Your only other fix may be a tighter A/R on the turbines (along with enough wastegate flow capacity to avoid being a restriction up top).