Hey guys, I want to build a mild 6.2L setup using a stock 10.7:1 longblock and a TVS1900, either an LSA blower or a Magnuson kit. I really want to use the BTR Stage 1 Positive Displacement cam, but I know cam selection could possibly be tricky given that the BTR PD cams are generally based around the 9.1:1 LSA compression. The combo will be primarily tuned around CA 91 octane gasoline (no meth) and a flex fuel sensor for E85. Any thoughts?

 

Static CR is not going to change the cam dynamics but it will limit your boost potential. On E85 it will be fine, on pump your not going to get very far before detonation issues although the cam will help. Boost and pump gas kinda sucks imo, its almost not worth doing unless you have a low compression engine and even then adding cubes and building a mean pump gas NA monster tends to be more reliable in my experience, and a LOT easier to cool.

Regardless I get tempted as well to stuff one of those maggies on mine too. Its so easy to install but the way I drive? Boom

 

Those cams are generally made for the slightly lighter cars and as such can feel doggy in a truck. Compression will help bring that back for you. I don't hate the selection although I do think you can do a little better.

Why did you choose the stage 1? Was it for the power characteristics you thought would be best for the truck, or was it for the "stage 1" manners? I could help you whip up some specs that you would probably be more happy with than that cam.

 

I figured since the CTS-V's are 4200lbs that those cams would be a decent fit to my 77 swb, which weighs ~4200lbs. Im certainly not looking at the Stage 2/3/4, only the Stage 1. I'm considering that cam because I want to build a torquey street truck, not a 1/4 mile truck in the slightest, it probably won't ever see the track. Also, I like the mild idle sound of the BTR positive displacement stage 1 cam. I really dislike donkey dick sounding cams.

I'm all ears as to what you'd recommend, thanks for your insight so far.

 

Ah ok cool. Yea it would be fine then.

I was thinking this would be in a newer truck that came with a 6.2. If its in a 4200lb truck that should work well. I tend to lean toward tightening the LSA a little. It helps mid range and part throttle power. You do get a little more chop in the idle though.

 

I wanna hear your recommendation for a 5500 lb truck, especially now that they make a torque version of the BTR cams.

 

It depeneds a lot on the combo... what converter, what kind of miles are driven, what kind of manners are wanted, what shift RPM's, what are all the supporting mods, how much boost... list goes on.

For an OE L92 truck thats 4x4 wanting a mild cam for great mid range torque and a 1900 blower at maybe 10psi or under and maybe a 6k shift RPM I would probably do something like this:

216/234 116+4 with intake lift close to .600 and exhaust lift below .600

216 is relatively short duration, but being on a 112 ICL its plenty to get you just beyond 6k RPM or so with a square port head. Especially with a friendly and stable lobe design.
In your truck with a cathedral head it would look more like this:

218/230 116+3.

With less focus on the manners of a stage 1, and more on a punchy heavy truck cam they would look like this:

Square - 220/236 114+4
Cathedral - 222/234 114+4

Max effort in your truck with those heads being as heavy as it is:
224/238 114+4. A couple degrees of overlap but nothing major. Early enough intake close to give it some pop off the line with that tight factory converter and heavy weight. I would guess your max boost is in the range of 12-13PSI with those cubes? The cam would pull to 63-6400 just fine...

 

I like what you are thinking, but I don't mind the cam pulling to 6500+ if it doesn't sacrifice too much down low. The old combo shifted at 6800 and it was intoxicating. This one had maxed out the factory MAF around 52-5500 RPM(depending on ambient temp) and so I have been working through getting one 3d printed to fit my intake setup. I also knew I was going to run out of injector at about the limit of factory MAF and so I upgraded injectors to 1000 CC at the same time. That is all coming together now and I am working on getting the tune lined out to take advantage.

Before this round of updates I was seeing about 11 PSI max, but I did find a leak around my IAT sensor which may have been worth something. I wish I could get the pullies setup to run in the 14-15 PSI range, but that'll take more machine work on the blower to fit smaller pullies.

Without doing any math, I had personally thought that something with a little less split 224 int/238 exh and a 116+6 would be right so maybe its just a difference of opinion on the amount of overlap I would want.