Designing Camshafts

Saron81 said:

Most boosted engines won't like a lot of overlap either from what I've seen. Don't see much of a gain here... and certainly not any that couldn't be made (for free)  with a little more boost, or even timing changes.  Custom billet cams for a challenge car is crazy talk. 

If I had to buy custom billet cams you're right. But according to Challenge rules anything I make only costs me material  costs.  What is the cost of a pair of junk crankshafts?  They are just machine time away from becoming blank cam cores. 
   So I haul those to my local cam grinder  and for $300 ••• custom billet cams. 

frenchyd said:

Saron81 said:

Most boosted engines won't like a lot of overlap either from what I've seen. Don't see much of a gain here... and certainly not any that couldn't be made (for free)  with a little more boost, or even timing changes.  Custom billet cams for a challenge car is crazy talk. 

If I had to buy custom billet cams you're right. But according to Challenge rules anything I make only costs me material  costs.  What is the cost of a pair of junk crankshafts?  They are just machine time away from becoming blank cam cores. 
   So I haul those to my local cam grinder  and for $300 ••• custom billet cams. 

Camshafts do not work that way.

It's probably best if you pause posting and start reading.

frenchyd said:

A properly designed set of racing headers only picks up 20 horsepower. 
       

I promise you that is nonsensical statement.  Normally, replacing log type intakes with a decent set of headers and matching exhaust is 10-15% so 20 hp on a 300hp stock engine is below the very bottom, but lets say it's real..20hp when all else is stock so 7%.  Then you add turbos, and you have 500hp, now the headers are 33hp.  If you are messing with cams the goal is increased air flow,  the headers will become more effective.  If you are also trying to increase RPM, you need even more flow and the headers become more effective again.  There is a pretty good reason headers are normally the 1st thing added....unless that 1st item is turbos.

As for not knowing what to put into the software, yes you have to know what you're doing to design a good engine hence the expression  "software makes a good engineer fast and everyone else dangerous".  If you need help with figuring out the correct inputs let me know what software you have and what the question is and I will try to help.

Javelin said:

frenchyd said:

If I had to buy custom billet cams you're right. But according to Challenge rules anything I make only costs me material  costs.  What is the cost of a pair of junk crankshafts?  They are just machine time away from becoming blank cam cores. 
   So I haul those to my local cam grinder  and for $300 ••• custom billet cams. 

Camshafts do not work that way.

It's probably best if you pause posting and start reading.

I made my billets so "free"....but the steel I started with was $100 per camshaft (8620)  then the cam grinder charged $100/lobe to rough grind, heat treat, straighten and finish grind them bring the total to $5200 12 years ago.

Working with used blanks (I was changing firing order so no blanks existed) last I knew, Webcam charges $100/lobe to weld and grind, $50/lobe to just regrind.   so on a 2 valve V12 that is $1200-$2400....and the challenge is over.

Javelin said:

Camshafts do not work that way.

It's probably best if you pause posting and start reading.

No they don't, its generally how a frenchyd thread works, though.

frenchyd said:

 

I did that too, worked with my simulator. 
    But I only had the ability to use  100% Methanol 

    Am I overthinking E85?   If I stayed at 12 pounds of boost  with Methanol my air temps only went up to around 150 degrees.  Changing timing gave a really serious power increase. Close to 50 hp if I remember it correctly. 
but I'm sure that's wrong. Because there was no power difference between the heron head and the fireball head. 
   I'm sure you know this but for others. The heron head is flat with a Hemi combustion chamber in the piston. 
The Fireball head is designed to concentrate the fuel charge around the spark plug. 

It a garbage in-garbage out thing I'm pretty sure.  E85 is not 100% methanol, I'd need to look it up but...10-15% difference I think. 

When you say changing timing....you mean cam timing?  At 500hp that is 10%, so sure, that is certainly in the right ball park or possible.  Its a free flowing exhaust gain.  Its porting the heads gains if you know how to do that work.  Its also a couple psi boost change so why bother?  Its certainly not the biggest bang for the buck.

mke said:

Even then....yes can shift things a bit by changing the lobe centers, but not a ton

I have some data that says otherwise, but only IRL. We have done things like backed the intake cam one tooth to give more clearance with full vvt, and seen gains in the top end that didn't make sense. Exhaust seems to do less, usually we leave that locked.

Also, turbo, most of the time just the stock grinds are fine because you make more power easily by just turning the boost up. I have one customer with a 2.8, huron style head, making over 600whp on e85 stock low lift, low duration camshafts. Just a cam swap is worth ~100whp but why bother 

In reply to Paul_VR6 (Forum Supporter) :

Please don't take any comment I've to mean always or never.    Moving the cams matters....but on an enigne like mine that is, if I'm being honest, over-cammed, there is the right location and there is everywhere else.    And being more honest, that is normally the place I find myself in becasue if I'm going to change a cam I want everything there is to be had from it.  I guess I was saying there is a window where things work and if the cams are lower duration than that,  there would no doubt be more to be gained or lost retiming them.

On turbo or blower engines I certainly didn't mean to imply that cam, intake, exhaust, compression, etc.  don't matter, they matter exactly the same as in a non-boosted setup.  All I was saying is if you can turn the screw on the wastegate or type a new number into the boost controler, well that is a whole lot cheaper and easier than changing anything else.  A lot of late 70s- 90s engines have HORRIBLE cams but most people I know who go down the turbo or blower path leave them until there is a compelling reason to make the change, that's all I meant.

On a ferrari 308, the cams can set set as you please.  Unboosted that lowers the hp, but it tends to increase the boost by reducing blow-down and helps hp on boosted setups that are flow limited on the turbo or blower but costs hp when you can already get the boost past where you can control detonation.  Its case by case though I'm sure.

With our multivalve engines we probably tend to under-cam, as there are some pretty crappy low rpm things that happen in addition to weird mids where pulse tuning may help/not help. The whole thing is a complex mess for sure. My stock cams are 256* at 050 but new ones are 278/282* at 050 which are tiny compared to some sbc stuff.

I have another axiom for methanol fueled cars: no cam is too big, but that's for another day.

mke said:

frenchyd said:

A properly designed set of racing headers only picks up 20 horsepower. 
       

I promise you that is nonsensical statement.  Normally, replacing log type intakes with a decent set of headers and matching exhaust is 10-15% so 20 hp on a 300hp stock engine is below the very bottom, but lets say it's real..20hp when all else is stock so 7%.  Then you add turbos, and you have 500hp, now the headers are 33hp.  If you are messing with cams the goal is increased air flow,  the headers will become more effective.  If you are also trying to increase RPM, you need even more flow and the headers become more effective again.  There is a pretty good reason headers are normally the 1st thing added....unless that 1st item is turbos.

As for not knowing what to put into the software, yes you have to know what you're doing to design a good engine hence the expression  "software makes a good engineer fast and everyone else dangerous".  If you need help with figuring out the correct inputs let me know what software you have and what the question is and I will try to help.

I understand the doubt you have about my statement regarding headers.  Almost always you are right. However Robert Knodt on his UTube Channel, Camp Chaos Cronicals   Will show you.  
or if you look at the Group A cars racing in Europe and Australia you can actually see 500 horsepower through stock (ish) intake and exhaust.  
      If you look at a V12 in a Jag with real headers ( not just tubular manifolds) you will see the other "cost". Which is lack of airflow through the engine compartment. Those pipes take up every available inch of that compartment. 
       My turbo's are intended as a cheap and easy way around the 20 horsepower gain headers make.  For one thing the turbo's won't be in the engine compartment  but rather under the front fenders behind the tire.  
       The game changes once I vintage race where turbo's won't be allowed.  So I may spend the time to make and fit a set.  
   When I made the headers for my XKE V12 race car I used 27 feet of tubing. Eventually cutting into the rocker panels. 
    

Paul_VR6 (Forum Supporter) said:

With our multivalve engines we probably tend to under-cam, as there are some pretty crappy low rpm things that happen in addition to weird mids where pulse tuning may help/not help. The whole thing is a complex mess for sure. My stock cams are 256* at 050 but new ones are 278/282* at 050 which are tiny compared to some sbc stuff.

I have another axiom for methanol fueled cars: no cam is too big, but that's for another day.

See that's the thing I really believe.  I think I'm missing something using E85 because  the difference in flame front of alcohol burning versus gas. 

In reply to Paul_VR6 (Forum Supporter) :

I wonder if you are getting at .050 and advertised duration mixed up. A 278/282 at .050 would be a MONSTER cam in an SBC or pretty much anything and you be hard pressed to find many options bigger (they do exist though) but is pretty mild as an advertised duration (normally. 005 or .006 IIRC) spec.

I still think Frenchy should send all pertinent info to a cam guy and let them draw him up some specs.

It's not as simple as add duration and it has this effect on power and rpm. Different cam grinders have different ways to do the same thing sometimes. A good example in the LT1s is a small LPE cam makes similar power to a much larger comp cam. The LPE raises dynamic compression to make power, the comp uses the more common practice of more duration and more overlap. You could also take 2 cams that look exactly the same in the common specs and give one a 106 LSA and one a 114 LSA and it'd be like 2 completely different engines. You also see this in LT1s, the conventional knowledge for old school gen 1 SBCs was a tight LSA was best, the major cam grinders said this wouldnt work when  fuel injected engines came out, everyone moved to wider LSAs but some smaller cam grinders still use a tighter LSA and have awesome results. A full bolt on cam only LT1 through an M6 will normally dyno between 330 and 360 rwhp, with pretty much any of the 50 or 60 common cams that are used, those are strikingly similar results for the massive differences in the way they are specced. Generally the biggest differences are in drivability. There is more than 1 way to skin a cat is what I'm getting at.

Either have someone spec you a cam, or find an engine similar to what you are building and copy them.

Otherwise you'll get lost in the options or internet wisdom without real results and end up with something not great.

Also the cam selection is only one part of the equation, intake and exhaust are just as important. Look at the differences different style intakes have on the same engine.

Hey Frenchy,

This video explains short vs long rods and the effect on power production really well.  It might help your cam exploration a little bit

Paul_VR6 (Forum Supporter) said:

The whole thing is a complex mess for sure. My stock cams are 256* at 050 but new ones are 278/282* at 050 which are tiny compared to some sbc stuff.

I'm goin to repart the @050? question  Those are big numbers for 050.  I've run 270 and had a buddy running 290@050 on a 2v, but on the 4V those are HUGE numbers.  I'm at 247/251  at the cam, 241/247 valve @050  and 273/285 @006 valve lift....and more lash to reduce duration adds hp.  But I also have pretty high flowing ports and large valves which both impact optimal cam choice....but a cam  with 278/282 @050 would cost me a lot of hp is my point.

frenchyd said:

 

I understand the doubt you have about my statement regarding headers. 
    

I don't think you do because everythig that followed was, well, honestly,  more nonsense.  A tuned exhaust is one of the most important things you can do to make hp on a 4 stroke engine.  Years ago I working in a shop that focused on Indian motorcycles and most of what the owner believed to be fact was based on ideas from the 1940s....that were gibberish.  This feels like talking to Chuck again.   An engine is an engine, there is nothing special about a V12 or a tight engine bay, or an Indian,  that changed the math in any way....a 4 stroke engine needs headers to make decent hp/liter.  

frenchyd said:

 But according to Challenge rules anything I make only costs me material  costs.  What is the cost of a pair of junk crankshafts?  They are just machine time away from becoming blank cam cores. 
   So I haul those to my local cam grinder  and for $300 ••• custom billet cams. 

I hope to see your car at the Challenge.  I'm so done with you twisting rules that your budget will be the first I go through line by line.

Paul_VR6 (Forum Supporter) said:

mke said:

Even then....yes can shift things a bit by changing the lobe centers, but not a ton

I have some data that says otherwise, but only IRL. We have done things like backed the intake cam one tooth to give more clearance with full vvt, and seen gains in the top end that didn't make sense. Exhaust seems to do less, usually we leave that locked.

Also, turbo, most of the time just the stock grinds are fine because you make more power easily by just turning the boost up. I have one customer with a 2.8, huron style head, making over 600whp on e85 stock low lift, low duration camshafts. Just a cam swap is worth ~100whp but why bother 

That's the number I keep hearing. 100 horsepower by going to higher lift longer duration.  For the street I agree why bother?  But for the race track where you can honestly use the extra power it's really a cheap  100 horsepower.  

frenchyd said:

  But for the race track where you can honestly use the extra power it's really a cheap  100 horsepower.  

$1200-$2400 doesn't seem cheap........

Stampie said:

frenchyd said:

 But according to Challenge rules anything I make only costs me material  costs.  What is the cost of a pair of junk crankshafts?  They are just machine time away from becoming blank cam cores. 
   So I haul those to my local cam grinder  and for $300 ••• custom billet cams. 

I hope to see your car at the Challenge.  I'm so done with you twisting rules that your budget will be the first I go through line by line.

I keep asking if I'm doing things wrong.  Check with my XJS  progress If you think I am please let me know.   

mke said:

Ifrenchyd said:

  But for the race track where you can honestly use the extra power it's really a cheap  100 horsepower.  

$1200-$2400 doesn't seem cheap........

I'm not sure where you get that number.   My local cam grinder tells me he will charge $150 per cam. Isky will do it for $480 for the set.  
      As far as  making my own cores and having them ground. I'll run whatever numbers I come up with and see what gains I make for how much horsepower.  Using the simulator program. 
    I've already done it for pistons and the pay off just isn't there. Even modifying Buick pistons. 

mke said:

frenchyd said:

 

I did that too, worked with my simulator. 
    But I only had the ability to use  100% Methanol 

    Am I overthinking E85?   If I stayed at 12 pounds of boost  with Methanol my air temps only went up to around 150 degrees.  Changing timing gave a really serious power increase. Close to 50 hp if I remember it correctly. 
but I'm sure that's wrong. Because there was no power difference between the heron head and the fireball head. 
   I'm sure you know this but for others. The heron head is flat with a Hemi combustion chamber in the piston. 
The Fireball head is designed to concentrate the fuel charge around the spark plug. 

It a garbage in-garbage out thing I'm pretty sure.  E85 is not 100% methanol, I'd need to look it up but...10-15% difference I think. 

When you say changing timing....you mean cam timing?  At 500hp that is 10%, so sure, that is certainly in the right ball park or possible.  Its a free flowing exhaust gain.  Its porting the heads gains if you know how to do that work.  Its also a couple psi boost change so why bother?  Its certainly not the biggest bang for the buck.

 No mke. 
    Jaguar basically has two different heads 

 . The first is called the Flathead. No combustion chamber at all. 
     The second is called the HE. They are basically Buick Fireball heads. 
     Both make the same power.  The difference is the HE heads have 11.5-1 compression   while the Flatheads have 7.8-1 compression. 
same power.  
   The Fireball heads have something like 8 degrees of ignition timing while the flatheads have 38 degrees. 

frenchyd said:

mke said:

$1200-$2400 doesn't seem cheap........

I'm not sure where you get that number.   My local cam grinder tells me he will charge $150 per cam. Isky will do it for $480 for the set.  

that is the 12 year old Webcam number.  The isky catalog says $480 is 6 cyl price if i read it right....no idea what anyone else charges but $150 for 12 lobes is the bargain of the century.

In reply to mke :

Last time I called Isky  ( around Thanksgiving ) they told me less than the $480 when I asked.     I just assumed that's a recent price.      
        The six cylinder has 2 cams.  But 12 lobes while the V12 also has 2 cams but 24 lobes.   I guess I should check. Because then Kent cams really aren't so far out of line.  
 The local guy mainly does  farm tractors and local hot rodders etc. but he did a set for my Black Jack with the Offy lobe masters. I haven't checked his prices  for a couple of years.  

mke said:

frenchyd said:

 

I did that too, worked with my simulator. 
    But I only had the ability to use  100% Methanol 

    Am I overthinking E85?   If I stayed at 12 pounds of boost  with Methanol my air temps only went up to around 150 degrees.  Changing timing gave a really serious power increase. Close to 50 hp if I remember it correctly. 
but I'm sure that's wrong. Because there was no power difference between the heron head and the fireball head. 
   I'm sure you know this but for others. The heron head is flat with a Hemi combustion chamber in the piston. 
The Fireball head is designed to concentrate the fuel charge around the spark plug. 

It a garbage in-garbage out thing I'm pretty sure.  E85 is not 100% methanol, I'd need to look it up but...10-15% difference I think. 

When you say changing timing....you mean cam timing?  At 500hp that is 10%, so sure, that is certainly in the right ball park or possible.  Its a free flowing exhaust gain.  Its porting the heads gains if you know how to do that work.  Its also a couple psi boost change so why bother?  Its certainly not the biggest bang for the buck.

mke 

Pump E85 can be 53-86 % ethanol and 15% gasoline. Or you can buy It by the 5 gallon can or 55 gallon drum.  
 Then it's 85 % ethanol  ( 114 octane compared to methanol's  116 octane ) and 15% 100 octane racing gasoline. 
No I mean ignition timing.  To prevent preignition  on America's 91 octane it's only 8 degrees. 
     

Does this the engine have the E type heads 

Or the later May Fireball heads?

on the later heads the exhaust valve is up high and really shrouded. they did this for emissions /MPG but it limits flow hugely. Lots of chat on the Jag forums about what  to do with them.

I think having a really good look at the flow is the first port of call rather than potentially pricey cam builds. Jag tuners tend to add capacity as these have huge potential and you can get 10L if you really try