Choosing a camshaft.. and how to match a turbo

[proxlamus©]

So I am definatly upgrading my camshaft.. I want more power!

 

However.. I was curious on how to build a camshaft based off my turbo..

 

I am looking for a cam where the turbo will spool up and build boost and the cam should come alive at the same time.

 

Now for a Holset for example.. full boost is around 3,600 RPM (16psi) .. now how to match that with cam specs?! oh boy.. now I am getting lost.

 

Z-gad developed his grind with a noticeable performance boost

Intake 490 lift 276 duration Lift

Exhaust 480 lift 266 duration

114* lobe center

44* overlap

 

Elgin Cam

Intake 480 lift 266 duration

Exhuast 480 lift 266 duration

112* lobe center

48* overlap

intake open was 21 degrees@50 and exhaust I believe if memory serves me correctly 72 degrees.

 

Isky cam

Intake 580 lift 290 duration

Exhuast 540 lift 270 duration

Lobe Center 114*

Overlap 55*

 

MSA Stage I (Schneider)

Intake .460 lift 260 durations lift

Exhuast .440 lift 250 duration

 

 

MSA Stage II (Schneider)

Intake .460 lift 270 durations lift

Exhuast .460 lift 260 duration

 

Schneider Stage III

Intake 488 lift 284 duration

Exhuast 488 lift 270 duration

Lobe 114

 

RaceTep

Intake 480 lift 272 duration

Exhuast 480 lift 274 exhuast

 

 

 

 

So it appears Z-gads grind is a bit beefier .. almost like a "Stage III" cam MSA would offer if they did manufactor it.

 

But how do I go about choosing a proper cam build for my Z?

[240zprace]

So I am definatly upgrading my camshaft.. I want more power!

 

However.. I was curious on how to build a camshaft based off my turbo..

 

I am looking for a cam where the turbo will spool up and build boost and the cam should come alive at the same time.

 

Now for a Holset for example.. full boost is around 3,600 RPM (16psi) .. now how to match that with cam specs?! oh boy.. now I am getting lost.

 

Z-gad developed his grind with a noticeable performance boost

Intake 490 lift 276 duration Lift

Exhaust 480 lift 266 duration

114* lobe center

44* overlap

 

MSA Stage I

Intake .460 lift 260 durations lift

Exhuast .440 lift 250 duration

 

 

MSA Stage II

Intake .460 lift 270 durations lift

Exhuast .460 lift 260 duration

 

So it appears Z-gads grind is a bit beefier .. almost like a "Stage III" cam MSA would offer if they did manufactor it.

 

But how do I go about choosing a proper cam build for my Z?

 

check out web cams and gude cams....

[JMortensen]

Just remember lift over .460 is going to require different valve springs and seals. Very much worth the hassle, but you will have to deal with those issues. Turbo cams have a lot less overlap than NA cams, so using the NA cams isn't a good idea. The smaller NA cams will work, but they're not much of an upgrade. I'd look at a cam with ~.500 lift, as long as you can get the overlap to a reasonable amount for the turbo. ZGad's looks good, and I think I remember him saying he got over 40 whp by adding that cam, although I can't remember what turbo he was running and don't know how it compares to yours...

[spork]

I'll second the reccomendation of going with a cam from web cams. I've got on in my car and am very pleased. Its not an "off the shelf" cam, so it cost me a little more, but it was well worth it. Pm me if your interested in the specs, and I'll dig them up.

[thehelix112]

Jon,

 

A performance turbo cam does not have small overlap. Stock turbo cams have small overlap to reduce reversion from restrictive exhaust manifold and turbine housings.

 

Also prox, doesn't Z-Gad run a 2JZ? Not really comparable IMHO. Apples and oranges. What lift/duration works on a 2JZ head might do exactly nothing on a L.

 

And one more thing, comparing advertised duration is next to friggin useless, get specs on 0.05" duration and go from there.

 

I think camshaft design is a very complicated field, add a turbocharger and you've got more complication. The best you can do is listen to other people's experiences and try to work something out from there.

 

FWIW I will be going with something around 240 deg 0.05 dur, and as much lift as I can squeeze into it. This should make max power close to 7000 I believe.

 

Dave

[JMortensen]

A performance turbo cam does not have small overlap. Stock turbo cams have small overlap to reduce reversion from restrictive exhaust manifold and turbine housings.

I thought that turbo cams tended to have less overlap and greater lobe separation angles than NA cams, even when done to the extreme. I don't have a turbo and have never bought a cam for one so I could be wrong, but that's what I've always read.

[BRAAP]

I thought that turbo cams tended to have less overlap and greater lobe separation angles than NA cams, even when done to the extreme. I don't have a turbo and have never bought a cam for one so I could be wrong, but that's what I've always read.

 

 

Jon,

Yes, that is true, the current trend for 2 valve turbo cam specs tends to have wider lobe separation angles compared to performance N/A, Super charged, and N2O cams for a given power band. In fact, I have seen a cam spec for a Turbo SBC V-8 that produced over 1000 HP and it had NO overlap at all, in fact, the exhaust valve closed, crank turns a few more degrees and then the intake began to lift off the seat. WILD!

 

Cam specs for N/A, Super Charged, and N2O, power plants are MUCH easier to nail down for particular power attributes over a given RPM range, but with the back pressure involved with the Turbo, all that goes right out the window.

 

The IDEAL turbo cam for any TURBONIC engine is still pretty much a black art. Intake flow efficiency, exhaust flow efficiency, Turbo design, boost being made, RPM range power is to be developed, intake and exhaust temps, intake to exhaust pressure ratios, etc are all factors that affect the “optimum” cam specs for a particular application and none of that can just be calculated. Basically, if we widen the lobe separation angle, it seems to be the safest route in terms of power gains with the least compromise for our beloved Turbonic L-6 power plants, or at least that is the current trend. This is not to say the IDEAL cam specs for that Turbo application wouldn’t be something altogether different, maybe with tight LSA etc, and as more of you Turbo guys try different cam specs for a given intake, exhaust, turbo combination and those same guys keep posting your dyno charts, we should start seeing trends in boost pressure vs power produced and power under the curve as well.

 

That’s my $.02

[proxlamus©]

Also prox, doesn't Z-Gad run a 2JZ? Not really comparable IMHO. Apples and oranges. What lift/duration works on a 2JZ head might do exactly nothing on a L.

 

he used to have a wicked L series build up.. he now has a 2JZ ..

 

the cam specs are for a L series

[thehelix112]

Prox, ah that makes sense, I didn't realise.

 

Paul, making 1000hp from any FI SBC isn't exactly pushing it if what I am told is true. (Especially dynojet hp). Who is to say said SBC wouldn't've made 1100hp with a more supercharged/NA type cam? That, and mentioning `trends' is not anything akin to an argument as to why less overlap is required. Do you have any known examples of L6 turbos that have made more power with less overlap? And what exhaust manifold/turbine housings were they running?

 

I assume you have read this article, but if not: http://www.grapeaperacing.com/GrapeApeRacing/tech/turbochargers.pdf

Page 6 is where it mentions camshaft selection.

 

I do completely agree though that it is a complicated task to properly design a cam for a turbocharged engine. Good luck with it prox.

 

Dave

[frank280zx]

I was reading on this http://www.datsport.com/Racer_Brown_Menu.html

 

very interesting stuff back to the read!! not much about turbos but loads on overlap etc

[73ZCAR]

Hey Prox,

 

Take a look at the stage 3 (17044) Turbo cam here. (Bottom of page)

 

http://www.schneidercams.com/cams/50.htm

 

It's a .488 lift so you may have to get the upgrades for the springs and retainers, depending on what you have now.

 

Pretty good duration, and with the wide lobe centers I think it may even pass emissions.

 

Pretty good prices too.

 

This is probably the cam I will use.

 

If you look at the specs for the stage 1&2 cams they look VEERRY similar to the MSA cams. Hmm.

 

 

Cheers, Mike.

[JMortensen]

The Schneiders are the cams that MSA sells. I believe you will have to upgrade springs and seals to run that much lift. I have a .490/280 NA cam and it required both upgrades. The seals didn't actually hit but they were within .010 I think, and my machinist recommended at least .050" clearance there to prevent damage to the seals. My suggestion would be to just run the Ford V6 seals (cheap and better than the CRAPPY Nissan seals) and get some Schneider springs and retainers. I'd also look at regrinds rather than a new cam. Regrinds are cheap and the metallurgy of the cam isn't in question...

[73ZCAR]

Thanks for the correct info , JM.

 

Mike.

[RTz]

From what I've seen, the more radical turbo engines (meaning primarily 4 valve, high RPM, high specific output) have been using some overlap. I suspect one of the things you gain is being able to blow out the clearance volume... otherwise, you end up with a chamber full of leftover 'exhuast'.

[(goldfish)]

I suspect that how much overlap you want to run has a lot to do with the amount of backpressure compared to the intake pressure. e.g TimZ has more intake pressure than exhaust backpressure.

[BRAAP]

Prox, ah that makes sense, I didn't realise.

 

Paul, making 1000hp from any FI SBC isn't exactly pushing it if what I am told is true. (Especially dynojet hp). Who is to say said SBC wouldn't've made 1100hp with a more supercharged/NA type cam? That, and mentioning `trends' is not anything akin to an argument as to why less overlap is required. Do you have any known examples of L6 turbos that have made more power with less overlap? And what exhaust manifold/turbine housings were they running?

 

I assume you have read this article, but if not: http://www.grapeaperacing.com/GrapeApeRacing/tech/turbochargers.pdf

Page 6 is where it mentions camshaft selection.

 

I do completely agree though that it is a complicated task to properly design a cam for a turbocharged engine. Good luck with it prox.

 

Dave

 

 

Dave,

I agree, 1000 HP from a Turbo SBC is very much attainable. FWIW, that wild cam spec for the turbo SBC I quoted directly from “David Vizard” and I was only using his example as an example of just how weird cam specs for a turbo engine can get. I apologize if that came across as a viable option for the L-6, that is NOT a cam spec I would choose or recommend to anyone. It was merely an example of a WEIRD Turbo cam used in an engine built by a well known reputable engine builder/tuner that did produce some power…

 

Here is that weird cam spec David Vizard used, (credit- David Vizard, “How to build and modify Small Block Chevrolet Camshafts and Valve trains”)

 

 

 

You are also right in my quoting “trends” really isn’t helping this thread whatsoever. Having actual empirical data to make an argument one way or the other is what you guys after here, not “trends”. I apologize for wasting bandwidth.

 

 

I wish I had more empirical data with Turbonic L-6 engines and cam specs. I have built several custom heads for Turbo L-6 engines, but I don’t have any real tuning time with them on the dyno or otherwise, sorry. My specialty in tuning and parts compatibilities is with N/A and Super Charged engines. They are MUCH less complex in regards to what does and doesn’t work compared to Turbo engines. N2O engine build ups also fall into the “easier than a Turbo build up” category. As I said, ideal Turbo cam specs is a black art. It would be nice to see the data gleaned by the Electramotive group from their extensive testing with the Newman Sharp 280 ZX Turbo...

 

 

Back to the discussion at hand;

In talking with another member on this forum that is currently running a low 11 second Turbo L-6 street Z, he went for a ride in Zgads turbo L-6 with the Zgad cam and mentioned that it ran great and made respectable power everywhere. Also, another member on this forum that lives just across the state line is currently running that same Zgad spec cam in his Turbo 280Z street car, and that is the same cam I installed in the PINKS cylinder head we built, (too bad that engine never did get “dialed in”. BTW, has anyone heard from the new owner of that power plant? Would like to hear how well it runs with some actual tuning time on it.)

 

Any how, the Grapeape link you gave is great, thanks. In their write up they mentioned that when the turbine housing is well matched, that LSA’s between 112-114 works well. The Z gad cam is ground on 114 LSA. Based on that, (barring any trends ), it sounds like the Zgad cam might be on the right track?!?!?!

[thehelix112]

All good Paul, I would love to bump into some ex-electramotive engineer willing to talk too.

 

Dave

[OlderThanMe]

Paul, The owner of the Pinks motor is in college(1500 miles from his Z) and will be installing the motor in the spring. That is what he told me...

[jeffp]

The first grind was .480 lift intake/exhaust 266 duration intake/exhaust Lobe center 112 degrees. I think that is about 48 overlap. intake open was 21 degrees@50 and exhaust I believe if memory serves me correctly 72 degrees. You can run the numbers and that cam came from Elgin cams in CA.

You can easily get power from that cam, and if you have the correct combination of turbo and some mild porting, you will get spool @ 3K rpm,s Your topend will be right around 6K and you can run up to 7K

The second cam is an Isky part, this cam is a little more radical, and I would not recommend going past this specification for any turbo L28.

55 degrees of overlap, .580 lift intake/ .540 lift exhaust lobe center 114, intake opens 31 BTDC exhaust opens 67 ATDC 290 duration intake 270 duration exhaust.

Those two grinds will do just about whatever anyone with a turbo could want. The Elgin cam works very well, the Isky cam is really good, but it more of a topend cam.

[thehelix112]

What 0.05 duration on the isky cam jeff?

 

Dave