Camshafts

I'm building a centrifugal-supercharged QV engine and actually have a similar question. It would be interesting to do some cams that complement the peaky nature of the supercharger and allow for more RPMs for example. I see a few companies out there selling custom cams (NFF, Superformance, a few others?) but not a lot of folks talking about what the goals of those specific cams are, before/after dyno charts, etc

 

We do custom cams. Feel free to reach out.
Highly suggest moving to shim under for aggressive grinds and boost.

 

I am assuming there isn't much you can do with cams on a QV with the stock FI and ignition.

 

For higher RPM even without raising BMEP I'd be more worried about the rods than the shims.

That same connecting rod has been used since the 250 motors and there are a lot of Ferrari blocks with big holes in them trying for a few more RPM. Be happy it lives to 7600. First thing I ordered for my 328 motor was new rods. Rods to fit that motor have a catalog # at Carrillo and for good reason. .

 

Many years ago together with Ron Iskiandarian I did a lot of experimentation with a Mercedes 6.9 with CIS. Long story short, forget about doing cams in a CIS car. European cams had just a few more degrees than we did and its all they can take. CIS requires substantial positive airflow under all conditions and performance cams have flow reversion under some circumstances and CIS cannot tolerate it.

 

Exactly!

 

I’ve discussed this with Dimi Elgin quite a bit. He confirms Ferrari’s stock cam profiles and ramp acceleration in stock engines are pretty darn lazy sans the early Dino and Daytona profiles.

Elgin‘s shop and webcams in Riverside, CA have done an awful lot of Ferrari cams, with most of them likely being naturally aspirated. Both have an outstanding master list of lobes to chose from, with their guidance I’m sure something could be figured out.

For CIS users, rifledriver is exactly right in that your cam options are not ever going to be that hot. With different valve springs you could likely find a grind that offers a lot more lift, say around .400 (stock CIS is something like .325 lift) but duration I want to say cannot go beyond 225 @ .050 or thereabouts (I believe stock is some 217 @ .050)

 

There are always lots of thoughts about cams......

Personally for a 4V engine I tend to like something in the 240-245 degrees @ .050" lift. Mine are 242/247 at the lobe, like 240/245 at the valve with the lash, Web ground them for me on billets I made or they can weld up and regrind stock cams.. Cat Cams has some nice ferrari grinds, not all are shown on the web page so contact them.

Now, my valves are also big, the port flow is high and the lobe accel rate quite high and the simulation software says adding more duration does bad things not good....in a system all the parts need to match. Depending on header and intake tuning they peak in the 9000-10500 range, 9k in my setup and idle is 700-750 and smooth. With stock ports and lift that works with stock lifters the same duration would peak closed to 7000-7500? Stock is about [email protected] with low lift giving low accel raters.

Boost doesn't really change much until you start getting into [email protected] cams and even then not much with stock heads. Turbos like a little more exhaust duration than blowers generally.

 

I have a q.v. with the prancing horse turbo kit, and the problem with the stock cams is that there’s a significant amount of valve overlap because it’s naturally aspirated the lobe separation angle should be increased so the boost doesn’t go out the exhaust I was thinking of going to efi injection along with upgraded ignition and an intercooler so I could run more boost

 

It sounds like the problem is the CIS

...seriously though, what is the issue with the overlap in the stock cams is causing? There are at least a few dozen turbo cars out there running the stock cams with no issues so and the cams I was recommending would have more overlap so im trying to understand the problem that needs solving?

 

naturally aspirated engine like overlap that helps them breathe and be efficient. Boosted engines Don’t like a lot of overlap stock Cam motors are inefficient with turbos because a lot of the boost goes out the exhaust valve. you want to be 112 in lobe separation with boost and I think the stock cams might be 106,or 108.

 

Stock is 106, I ram a 10psi blower setup with no issues. When went to a 24psi setup I switched to the 108 euro timing just because it had a little nicer power curve in theory but nothing I can honestly say I noticed.

You can set the lobe centers anywhere you please, you just need a degree wheel and a dial indicator. I can plug it into dynomation for you tonight or tomorrow and see what it says but I'm pretty sure 112 will cost you hp because it will increase the spoilage ( exhaust left in the cylinder)

But I guess I'll ask again, are you having a real problem with your current setup that you are trying to solve?

 

This is a twin cam motor. Can we not dial in the overlap we want just by moving the two sprockets a degree or so in opposite directions? I'd expect the problem to be the duration instead - at ideal overlap the intake closes too late and the exhaust opens too soon.

 

Yes, degree wheel and dial indicator and set to whatever you please.

The stock cams are quite short duration.....fine down low but it runs out of steam around 6500-6800

 

Stock QV and Stock with turbo at 8psi, no cooler. Its losing basically nothing out the exhaust.
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Now cams at 106/106 vs 112/112.....106 is the clear winner. Its not a spoilage thing like I though, just less efficient timing
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Then for comparison my naturally aspirated engine with the 241-245 cams (I had the number slightly off last post). I have a bit more charge loss even with no boost then a lot of reversion here and there....more duration more problems which is why I like to stick to the 240-245 range to keep the problems manageable, then adjust valve size and port flow rather than keep adding duration. I'm using TR heads but they are very similar to QV heads...maybe not quite as good.



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Now add 8psi turbo and the hp doesn't bump nearly what you'd expect....because naturally aspirated its already over 11 psi at the intake valve at IVC n(bottom graph)...tuning is your friend. But now the charge loss to exhaust has about doubled. This is where duration wise it might be time to start looking at more LSA

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Sort of switching gears but on the same camshaft discussion, I have been told the exhaust valve opening sequence is the least important event so long as it occurs after 90 degrees on its way down after the power stroke. Can the same be said for forced induction engines or is this a NA consideration only?

 

Most boosted applications, run lobe separation angle of 112 to 114 and yes, since it’s a twin cam motor you could do that by advancing one cam and retarding the other but you could get in to piston interference. Perhaps I don’t know but at 08 in a boosted application, there’s definitely some efficiency being lost due to the tight Lobes separation angle

 

I ran the simulations for you...106 is much better than 112 for this application with the stock cams and as I said many people are running that setup with no issues.. The stock duration is just too short for it to really matter. If you add 20 degrees to both cams ([email protected] then you have 20 degrees more overlap and its probably time to look at different timing. If you tell me the can and turbo I can plug it into the sim and see what it says.

You will not have piston interference issues until you get way off factory timing...more than 15 -20 degrees before I'd bother checking

 

Not sure really. EVO starts the flow in the port so that plus the header/collector lengths sets when the savaging pulse will hit and ideally that is at IVO

 

Not as much of an issue because the stock duration is weak but with aftermarket cams with sufficient duration you’d want more lobe separation/less overlap.

 

Maybe...but I ran that simulation for you too on my setup.....very little loss at 8psi with extremely aggressive 241/245 cams at 104/110 so 107 LSA.

There is no magic cam angle. It's very setup dependant...port flow, valve size, header and intake tuning all matter which means a lot of dyno time or a good simulation program.

 

I eventually want to go coil on plug, EFI, intercooled, 15 lbs of boost, run that on the simulator if you wouldn’t mind. With a couple of Garrett GT 35’s

 

I picked randomly GT3582R....2 will cause surge so this is with 1, there is never more than 0.25% charge loss to exhaust. If you know the exact turbo model let me know. but I'd be looking at something much smaller if you want 2. EFI and plug on coils don't really change anything in the simulation other than with CIS I would add in some flow restriction and don't knowing its EFI. 15psi is about the limit with stock valve spring before you worry about intake float but the rest of the engine will handle more like 25 as long as you make sure there is no detonation, that kills the flame rings in the head gaskets....ask me how I know
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I can’t read the graph due to resolution, what did it make tq and hp.