Cam info for turbo

[Badbird_96]

I'm pretty sure im about to buy a cc306 cam. If you don't know I'm going to build a custom rear mount turbo setup. Planning on 7psi and probably going to use a T67 as I don't want to have to upgrade my turbo later for the 383 build. What is a good valvetrain for this kind of setup? Planning to cam it first then the boost will come later. I'm sure this has been asked alot but I figure going boosted might make a difference

[ZGOBYBY]

CC306 would not be a good turbo cam. Moe would have some good recommendations. Most CC306 have a 112 or 114 LSA; with a turbo cam, you would want something with a higher LSA (115 or so). In reality, you don't want an aggressive cam like that for a turbo.

[dawdaw]

Ya pick some of the turbo guy's minds on here and you'll find someone to help you with your cam selection... I have no clue on turbo cams but it seems like everyone's build I see is a wide LSA cam with relatively mild lift and duration.

[sick70malibu]

Ya pick some of the turbo guy's minds on here and you'll find someone to help you with your cam selection... I have no clue on turbo cams but it seems like everyone's build I see is a wide LSA cam with relatively mild lift and duration.

Correct me if I'm wrong but from the things I have heard a lower LSA would benefit a boosted application. However I honestly have no idea.

Subbing into this thread so I can get me edumacated bout them fancy turbos.

Sent from My HTC Rezound

[Badbird_96]

I heard the samething but Sean informed of a member (the srz I think) had one on a supercharger car and makes great power with it. So that being the case imma get it and use it for now and later when I do my 383 build I will probably do a custom grind

[popo8]

I heard the samething but Sean informed of a member (the srz I think) had one on a supercharger car and makes great power with it. So that being the case imma get it and use it for now and later when I do my 383 build I will probably do a custom grind

Remember he is also pushing ALOT of boost....

L.E. is who i spoke to for my boost cam..... think its 114 lsa.... or maybe it was 112... my binder is in the camaro...

TapaTalk ROCKS!!!!

[Fastbird]

SRZ is making 720 at the wheels, stock ported heads on a 383 with an F1 procharger, using a CC306. My cam in my turbo car is a 234/244 .610/.610 110* LSA on a 108 ICL. It's NOT a super turbo design, was for a blower originally. It's a Bret Bauer cam, and he and I extensively talked about it and came to the conclusion that it's not giving up anything over a wider LSA cam.

Truthfully, you can take ANY cam, run it N/A, make power, add boost, make more power. It is but it isn't that simple, as the overlap plays heavily into the equation, especially on the turbo setups. Some cams benefit more from changes for boosted applications, but throwing boost on the car won't make you lose power with no other changes. For a turbo, a lot of guys like a wide LSA and a reverse split where the intake duration is longer than the exhaust. I don't understand that myself because I'd think longer exhaust duration would keep more pressure in the up pipe keeping the turbo spooled better. Look at the LPE turbo cams for example, the GT2-3 at 204/220 with a 117* LSA, and the GT7 with a 214/230 (IIRC) duration and 121.5* LSA. Both are crazy efficient and make AWESOME power in boosted applications. I had a GT2-3 in my Vette with NO exotic parts, and made 761/760 at a meager 14 PSI boost. For an LT1, my personal thought is that you'd HAVE to have a wide I to E standard split due to the LT1's weak exhaust side. I'd like to see how a cam in my car would do with something like a 224/240, high lift, and about a 115-117 LSA.

[Badbird_96]

Well Sean should I buy it? Got a great deal on it.

[Fastbird]

I say go for it. There's MUCH worse cams to have than the CC306.

[Badbird_96]

Good deal. Ok back on topic what should I get to upgrade my valvetrain

[firebird_1995]

Wait before we get back on topic can I just ask, I realize that the exhaust drives a turbo and the engine drives a supercharger but what is it about a cam that makes it better suited for a turbo or supercharger application? I guess what im trying to ask is what takes place with a larger lobe separation that makes a turbocharger perform better than a lighter lsa?

[Badbird_96]

Good question I don't know either

[Fastbird]

Wider lobe sep is a big factor in the total overlap of the cam. Wider the lobe sep, the less the overlap. Overlap on a turbo car is bad, but a blower car can deal with it. it's why you see blower grinds looking like N/A grinds a lot of the time. But on a turbo car where the exhaust is the driving factor for the power adder, overlap can kill off exhaust pressure due to the amount of time both valves are open allowing some of that exhaust gas back into the combustion process. So if you lower the overlap, you gain those lost exhaust gasses, and keep more heat/pressure in the hot side before the turbo.

The same doesn't hold true for a blower. It's RPM dependent, so it's gonna see boost no matter what. It CAN be affected, but like I noted above, blower grinds usually will look like NA grinds anymore with pretty tight LSA's.

I tried to make that as simple as possible. This isn't an expert opinion by any means, just stuff I'm familiarized myself with. It's on the internet, so only about 10% of it is probably true, lol.

[Badbird_96]

The same doesn't hold true for a blower. It's RPM dependent, so it's gonna see boost no matter what.
The true 10% lmao

[firebird_1995]

That explanation made perfect sense. Thank you!

[CamaroZGuy]

the smaller cam is more efficient with low boost and at lower RPM. The big cam works better when more boost is cramming the cylinders and at high RPM.
Overlap is when the intake and exhaust valve are open at the same time. Overlap and boost do not work well, it allows the boost to go out the exhaust valve instead of packing the cylinder and building boost.

The larger cam has 14 MORE degrees of overlap than the smaller cam so there is more boost lost out the ex valve and builds less boost. The larger the S/C and the more boost you create, the more you can get by with wasting out the tail pipe "assuming you are gonna spin enough RPM to actually use the gains of having the valve open longer with more duration and make the smaller cam limit cylinder filling".

The larger intake duration also keeps the intake valve open longer and you don't actually start trapping cylinder pressure until the intake valve closes. This is another reason that the smaller cam helps with lower boost set ups. It starts building boost sooner (less overlap putting wasting boost by going out the tail pipe and closes intake valve sooner so it starts trapping cylinder pressure sooner) so you make more HP/TQ at EVERY RPM up to 5500-6000 RPM where the larger cam will actually make the same HP and then surpass it and "can be" 20 HP better at 6500 RPM and "can be" 35 HP better at 7000 RPM.

Now when I say "CAN BE" above, I am talking about the potential of both camshafts only and to see these gains it will require no other restrictions in the set up. as long as you have a larger enough air inlet, MAF, duct work, TB size, fully ported intake, etc so that ALL of this can keep up at this RPM/HP level . . . . . . . . . . . AND a good enough cylinder head, header and exhaust system that can keep up at this RPM/HP level, it is "possible" to see these HP gains.

If trying to use a the stock S/C air inlet, F body MAF, factory elbow, un ported intake, 1 3/4 LT's, ORY and cat back exhaust, you will NEVER see this kinda gain at high RPM due to each and every one of these things being the restriction. If the heads are less than 2.200" at the pushrod pinch and less than a 2.08 intake valve, it will never show these gains with the larger cam at high RPM, even if you do have everything else that is free flowing.

SO, in order to see the gains at high RPM you will need a custom air inlet, duct work, MAF and elbow that allows ZERO difference in boost when checked at these points compared to boost in the intake.

You will need a 58 MM TB, fully ported intake, 2.08 intake valves, FULLY ported AFR 210's opened up to 2.200-2.400" at push rod pinch (if starting with an LT4 intake we can actually get 2.400" here), a set of 1 7/8 LT headers, 3" True Duals with X pipe, Bullet mufflers and dumps at rear end.

THIS set up would actually be able to see the 20/35 35 HP gains at 6500/7000 RPM over the small cam BUT the smaller cam will still make the same HP at 5500 RPM, 20 more HP at 4500 RPM and 40 more HP at 3000 RPM.

If you do not have all the parts mentioned to see the the gains at high RPM, there will be very little to no gains up there with the larger cam and so you might as well take advantage of the extra HP/TQ thru the entire RPM range of the smaller cam.

Quote Lloyd Elliott

this is more talking about my build but i think its a fairly good explanation

[Fastbird]

Great explanation from a guy who understands it better than I. But hey, I think I was on the right track, lol.

[CamaroZGuy]

you deff know more about it then i do, but thats y i got about 20 emails back and forth with LE...lol

[Badbird_96]

Makes sense. I'm still gonna go with this cam for now as for a time it will be NA until I have time to build my rear mount. But when my 383 build starts he is going to be the man I'm going to. It will probably be a custom grind cam by him that replaces this one. Mainly the rear mount for now will be setting up for the 383. If it has a bit of lag from the bigger turbo and cam that's ok like stated earlier it will still make power and as this isn't my ending setup it doesn't have to be 100% efficient right now. Btw Sean I was considering going t76 or will the t67 be enough for the 383. Don't wanna redo it ya know

[bigtoyz]

I generally like to stay out of topics like this now from getting told I dont know what I am talking about since some people have gotten lucky with the choice of cam and turbo size. Cause it made x amount of power on someone elses system.

But what a boosted cam does weither supercharger or turbo. The higher the LS the shorter the valves are open together. For a NA motor the two valves are open longer to make the scavangine effect work better 106-112 LS is typical. Basically getting the exhaust to help put in a little bit more of the intake charge. With that it is possible that you may loose some new A/F mixture out the exhaust. But for a NA motor it makes more power.

Now with the boosted grind.......the exhaust valvle stays closed longer to the cyclinder pressure to build up and opening quicker to get rid of the exhaust charge. 114+ LS

And I think there is a geneal mentality that people go with to big of cams. I think the ones with 230+ intake are for the big boys. And I am not talking about 1000+1300hp boys either. But the cam makes see that people want bigger cams cause they think it will make more power becase some buddy put a 230/236 cam in his and made 50hp more. When all he maybe all have to had done is turn up the boost...and make more power. I had seen a build that made 1000hp F1 procharger that got 26 mpg on interstate doing 80mph was a LSx motor but basically stock bore and stroke...had forged internals and a pretty conservitive cam by today standards. Think it was something around the size of mine 224/230. But cam selection is what you want out of it too. Some like the loop and to get that either low LS or bigger cam. With my 383 you could pull up to it and swear it was bone stock.

With selecting a tubo. More than one turbo will work. BUT where do you want to make the power and how much. The compressure maps are your friend if you know how to read them. On that not T67 will spool faster and make more power sooner everything being equal. The T76 will make more power but at expensice of lag and doggy bottom end. But say 4500+rpm to 7000 grand it will blow doors off of the T67. But out on the the street the 67 would be better. In a drag race you can expect the 67 to be quicker off the line.....with the 76 being able to run it down. The 67 could probably make as much power as the 76 but it will be out of it effiency range. But that is where looking at the compressor makes come into play. There are only 2 compenies that actually make turbos. borg and garret, well honeywell is coming out with a new design now also. But the others are just mix and matching the housings and the turbines.

Now with compessor maps you have to cut them in half if your doing twins. Lets say for twins and a 383 witch is about 6.3-6.4L off the top of my head. Your gonna have to look for a turbo that will support upto 3L or so usually 1.6-3.0L they will maybe say. So now with that said......since we are on the upper end and wanna make 800 hp so each turbo has to support 400 hp and depending where and how you wanna make the power depends on the size also.

Sorry maybe got a little lengthy but gives some people for food for thought. And if anyone wants to chat or something just let me know willing to pass on anything that I know on to help someone out.;)

[Badbird_96]

I will pm you later on this lol

[ZGOBYBY]

With turbo cams, you don't want a split in the duration (hence Sean's specs).