Heads Cam Journey Has Begun

[Sniper]

Nice!
Hoping mine comes back sounding half as nice as both these cars!

[Mikey]

yes but not tuned yet

https://www.youtube.com/watch?v=EzaxOlgPFj4


https://www.youtube.com/watch?v=iXsvjgdPmKc

I like it

[Mikey]

This is what mine sounds like

https://youtu.be/IRhVVaFuaDs

[Aevus]

correct me if I'm wrong but I think Dan Lesser said that a mild cam can give the rough idle sound, no need to go crazy if the sound is what you're after


edit: ''mild'' is probably something like 230/240 LSA 114 or so, as long as you have few degrees of overlap

[Aevus]

video on youtube that shows a Roe Racing 710r camshaft

https://youtu.be/PGDCbY7N3lE?t=96

which is 14 degrees valve overlap

[Viper Specialty]

correct me if I'm wrong but I think Dan Lesser said that a mild cam can give the rough idle sound, no need to go crazy if the sound is what you're after


edit: ''mild'' is probably something like 230/240 LSA 114 or so, as long as you have few degrees of overlap

Everyone just needs to remember, the "sound" that everyone likes is the sound of an engine inherently running poorly. IE: Dont be stupid on cam specification or you will regret it in the long run. That said, Gen-4/5 are more forgiving in this regard than G1/2/3 do the the MAF hybrid design versus true speed density.

[Mikey]

What's the eta for them to finish?

[Sniper]

You asking about my car?
They said 6-8 weeks but it could be sooner than that…

[Mikey]

You asking about my car?
They said 6-8 weeks but it could be sooner than that…

That's not bad at all!

[Sniper]

Everyone just needs to remember, the "sound" that everyone likes is the sound of an engine inherently running poorly. IE: Dont be stupid on cam specification or you will regret it in the long run. That said, Gen-4/5 are more forgiving in this regard than G1/2/3 do the the MAF hybrid design versus true speed density.

So, all the videos that have been posted are poorly running engines? And also Nth Motos cams are also running poorly?

[RedTanRT/10]

Everyone just needs to remember, the "sound" that everyone likes is the sound of an engine inherently running poorly. IE: Dont be stupid on cam specification or you will regret it in the long run. That said, Gen-4/5 are more forgiving in this regard than G1/2/3 do the the MAF hybrid design versus true speed density.

So true Dan!! In another 10 years when a number of performance cars go electric, they'll be companies selling piped in exhaust sounds that sound like a nasty cam and also can rumble and pop on deceleration!


Sniper, best wishes on your build!!

[Viper Specialty]

So, all the videos that have been posted are poorly running engines? And also Nth Motos cams are also running poorly?

Facepalm. Learn how an ICE & valvetrain works with regard to overlap, charge filling, volumetric efficiency, MAP and its relationship to cylinder air mass and fuel mass when dealing with cam profiles... and then get back to me, because my point flew way over your head.

Pretty sure I have taught numerous V10 calibrators how to calibrate, and have one of the earliest "start dates" of anyone in this market calibrating V10s.

Read more, post less.

[Sniper]

Facepalm. Learn how an ICE & valvetrain works with regard to overlap, charge filling, volumetric efficiency, MAP and its relationship to cylinder air mass and fuel mass when dealing with cam profiles... and then get back to me, because my point flew way over your head.

Pretty sure I have taught numerous V10 calibrators how to calibrate, and have one of the earliest "start dates" of anyone in this market calibrating V10s.

Read more, post less.

LOL your wisdom far surpasses mine. The only dumb question is not asking one.
Trust me, I’ve read enough that I won’t use your service.

[Viper Specialty]

LOL your wisdom far surpasses mine. The only dumb question is not asking one.

It wasn't the question, it was the implication in how you asked it.

The "Sound" or "Lope" that is associated with cammed performance engines is the sound of an engine that is inherently running poorly, yes. The goal of an engine is to maximize volumetric efficiency, however in the case of a cammed engine, efficiency at the high RPM range is favored in lieu of efficiency at lower rpm ranged where it becomes extremely inefficient and poorly running. This can be masked to a point by calibration, but it will never be gone. Temperament, surging, converter damage, EGT issues, trim lock, altitude issues, stalling, and high-idle, are all things that creep into the scene when chasing that "sound". The more extreme the sound, the more likely there will be a pile of nonsense that accompanies it. Once you hit the limit, the engine will become untunable. Make no mistake, WOT dyno tuning is literally 1% of a properly running calibration, and by far the easiest part.

Speed density based systems, while ideal for Forced Induction, are directly at odds with low-vacuum/large overlap engines, as engine load cannot properly be calculated as intended. MAF systems give a little more wiggle room as they are not as reliant on vacuum. However, charge and thus exhaust contamination are still a problem in the long run.

Short version: Donkey-Dick Camshafts make a calibrator like me want to hit you in the head with it and ban you as a customer for life.


PS- Since you edited, and thats fine. I cant keep up with the ones I have!

[Mikey]

Facepalm. Learn how an ICE & valvetrain works with regard to overlap, charge filling, volumetric efficiency, MAP and its relationship to cylinder air mass and fuel mass when dealing with cam profiles... and then get back to me, because my point flew way over your head.

Pretty sure I have taught numerous V10 calibrators how to calibrate, and have one of the earliest "start dates" of anyone in this market calibrating V10s.

Read more, post less.

I don't think he was being disingenuous

[Sniper]

I’m sorry if you took my post wrong. I was genuinely asking about what you stated as I know very little about engines.

[Viper Specialty]

I don't think he was being disingenuous

Anyone can interpret things incorrectly, including me... but when you see "So, ABC are all wrong, and XYZ is wrong too?" type comments, the implication is pretty clear and definitely defensive.

A non-defensive position would have simply been "Can you please explain what you mean?".

[Viper Specialty]

I’m sorry if you took my post wrong. I was genuinely asking about what you stated as I know very little about engines.

If thats legitimately how you meant it, then I apologize for my tone. I read your message as a fairly pointed slight.

[Sniper]

It was not a defensive statement.

[Sniper]

It was not a defensive statement.

And I’m sure I’ve made my shop pretty short as the questions I’ve asked them. LOL

[Mikey]

If thats legitimately how you meant it, then I apologize for my tone. I read your message as a fairly pointed slight.

As a mechanical idiot myself, I'd suspect his thought process was "What is the point of making the engine inefficient, and is this the case with every shop?"

[StrokerAce]

I get what was being explained but maybe it's that the engine is running poorly at idle. Which makes sense from my big block days with .77X lift cam with 300ish duration that didn't like to idle but that's not what it did most of the time anyway. Yeah, you could damn near almost hear each individual slug as the crank turned. Sounded tough and people liked to hear it start up but it didn't like to idle, but again not what it was for. So yes, at idle I agree it wasn't running great but it sure did like to slam 2nd gear in that powerglide at over 8k RPM's.

For a street car I'd rather error on the side of too small of a cam than too large. To VS's point, usually a Donkey D cam is for bragging and dyno results but fail to deliver in most street driving instances.

Just my experiences.

[Aevus]

Well, that escalated quickly!

hahaha


back to the topic:

I think one should have as big of a cam that is needed (strictly for high RPM use, not sound nor HP) but not a tiny bit more, because that's where headaches start.

and even for higher RPM, since the Viper engine is so limited (oiling system, hyd lifters, valvetrain, long stroke, etc..) you probably better stay below 6,500rpm anyways...

and if you're in it for HP, don't bother, just force induce the beast and call it a day


edit: I think Roe Racing (now bankrupted tho) nailed it with their latest cam version 710R with 14 deg overlap: it was most probably the maximum possible without heavy modifications and tuning issues.

[Aevus]

As a mechanical idiot myself, I'd suspect his thought process was "What is the point of making the engine inefficient, and is this the case with every shop?"

Mikey, upgrading the camshaft is just about deciding on a compromise. Anything with some sort of valve overlap simply make the engine somewhat unbalanced, especially at lower RPM.
The benefit of that (besides of the rough choppy idle sound) is the performance at higher RPM... Scavenging effect

https://help.summitracing.com/app/an...venging-effect

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You can visually see it there, on the graphs:

https://www.compcams.com/dyno-graphs

The ''bigger'' the cam, the peakier it is in high RPM, and the more absolute HP you get at the peak (at the cost of lower RPM performance)...

That being said, if you don't care about high-RPM performance... it's an absolute no-go to choose a very big cam. Especially with final gears between 3.07-3.55 and stock-ish valvetrain...

Maybe Dan can confirm, but I'd say anything between 10-12 deg overlap would be more that sufficient to have the sound AND the low-end torque AND something tunable.

More than that, you better have a higher compression, lighter/stiffer valvetrain, ported heads, headers/exhaust, 3.73+ gears, etc... Basically all I had to do for my 22 deg cam.

[Mikey]

Did you figure out what you're going to do for tuning, Sniper?
I THINK prefix just uses the standard race module for heads/cam, and then the custom tuning for the 9L builds