Designing Camshafts

In reply to mke :

mke. That's likely what I'm doing for the challenge. Bolt on a couple of cheap turbos  for the Challenge and send it off. But once the guys go to the challenge  then what?

     Build a car for one event?   Maybe if you have time,  money,  and live in Florida.  But it's a long tow from my home to There.  I'm sorry but auto cross and drag racing doesn't excite me the way wheel to wheel does.  
   I can't vintage race it with turbo's. 
 So cams and compression.  With a little port work.     
 But you're right mke, it gets hard to get much over .500 lift off the seat ( stock is .375) and duration if you're regrinding the stock camshaft it's very hard to get  serious duration. While if I copy what Pushrod V8's do they are over .700 lift off the seat and serious duration. 
    The stock camshaft was selected for fuel mileage and meeting emissions.  Not horsepower. Just regrinding the stock cam to Isky's XM 3 gains you 100 horsepower  but 600 horsepower is typically what the front runners have. 
   If I'm going to have a billet ground I'll need more than 100 hp. Luckily if you mix and match valves and cam followers the potential is there for more.  But to my knowledge they are still grinding to specs from the 1980's. 

I'm almost scared to ask this question but are they the right sizes for your application? Do you have flow curves or know where to find them?

In reply to mke :

Prediction: They're way too big.  He's gonna put in a restrictor plate to throttle them down.

mke said:

I'm almost scared to ask this question but are they the right sizes for your application? Do you have flow curves or know where to find them?

They are in the general range of acceptability, considering.

In reply to Paul_VR6 (Forum Supporter) :

Fair enough 

mke said:

I'm almost scared to ask this question but are they the right sizes for your application? Do you have flow curves or know where to find them?

They are T3's  the V12 I kludged together were  T 2's and only produced 5&1/2 psi boost. 

frenchyd said:

mke said:

I'm almost scared to ask this question but are they the right sizes for your application? Do you have flow curves or know where to find them?

They are T3's  the V12 I kludged together were  T 2's and only produced 5&1/2 psi boost. 

Saying T3 is like saying 15" rim, that doesn't mean anything other than a standard center cartridge size and possibly an exhaust flange size. What size impeller and turbine? What a/r ratios are they? Water cooled or oil cooled? Ball bearing or journal? Internal or external wastegate? 

In reply to Javelin :

I'm really trying to get information about cams.  As I said, one event of drag racing and autocross across the country isn't  what I want to do. But the guys working with me seem to want to do it. So I'll send the Jag down with them ( and my truck and trailer ) while I drive the  school bus. 
     Afterwards I want to go wheel to wheel vintage racing. ( turbo's not allowed).  So the camshaft is critical. 
     Now I realize you want to play Gotcha.   But I'll let you figure it out.   
    The Challenge rules limit spending to $2000. Do you think I can buy a new pair of ball  bearing turbo's  for $237?    With Water/Air intercoolers included?   I'm hoping  the use of E85  cools it enough to deal with whatever boost  I can generate.   If not I'll take the windshield washers and squirt WW fluid  in the manifolds. 
   
 I'm lucky my Jag came with a brand new Megasquirt or I'd be running it with carbs.   
     It's all part of staying within the $ 2000 limit 

In reply to frenchyd :

You still don't understand camshafts. Nobody here is trying to "gotcha", we're trying to help, but you don't read anything or understand more than just the barest of concepts.

Camshafts for n/a (vintage racing) and turbochargers are at direct odds to one another, period. Pick one or leave the stock cams in it. I still don't know how you intend on making cam blanks or will get anything like what you're dreaming of in budget.

In reply to frenchyd :

Im not telling you to copy what pushrod V8s do. Im telling you to copy what other jaguar guys do, if the info is out there. Im telling you to study what pushrod V8s do, because I know the info is out there. Yes the engines have different mechanical limitations, but you can see someone added 10% more duration and the effect it had over stock, or ICL or LSA or LIFT or overlap, and get a general understanding on what these specs do and stumble your way through specing your own, if your hellbent on doing it yourself.

V12 cams that already exist

and some more

and even more

Maybe those three links will help, I actually found a lot more information there than I had anticipated.

In reply to ¯\_(ツ)_/¯ :

Thank you. I'm familiar with Both Kent and Piper camshafts. In fact my Black Jack had a Kent billet. It was lovely.  Power just kept on coming past where I was willing to race with a stock bottom end. 
   I forgot about Bill Terry but I shouldn't have. He's always been at the front end of Jaguar racing here in the states. 
 There is also Rob Beere in England who offers camshafts. 

This is really 2 builds.  A challenge  build where cost is king. You can't really even afford gaskets so find a running engine and use it.

Then a vintage build where if you want to actually compete cost is no object...and it ain't so easy to go from 300 to 600hp and I'm reading 750 is probably where you need to be if winning is of interest....so the money must flow. This sure seems like a whole different engine....and whole different rest of the car too honestly.

In reply to mke :

it appears that the kent and pipers are both regrinds. That used to be real cheap on some applications.

In reply to mke :

The prep work on the chassis  ($500) is almost all labor, few bucks for roll cage material.   Then there is sales of parts not needed.  And trades.  Plus the fender flairs I spent $2000 on don't count since I'm going to use those as patterns to make molds off of. Only the material cost of making the actual parts count and those materials I bought more than 30 years ago back when I was making and selling fiberglass trailers. So they are bulk purchase price. 
      The only real expensive part is the pistons. I thought I had  some I could adapt.  But the cost of enlarging the pin holes is too expensive and I don't have my vertical mill anymore. 
  I saw a set of Cosworth pistons recently  but they sold before I called. Darn,  they are lighter and have a better combustion chamber.

      I've still got a while before I start building that motor. The motor that was in the car seems like a sweet heart. 90,000 miles and it turns over like butter.  Considering it's been sitting for at least 20 years it's amazing. Leak down variation  (with cylinders oiled )was only 3%  and that was on a cold engine.   That's the one going to the challenge.  All I'm going to do is drop the pan and weld in some baffles and splash rails.  Hoping to keep oil around the pick up. 
   If anything happens  to it I've got 3 complete spares and another in parts. opps and put on the turbo's. 

 

Opti said:

In reply to frenchyd :

Im not telling you to copy what pushrod V8s do. Im telling you to copy what other jaguar guys do, if the info is out there. Im telling you to study what pushrod V8s do, because I know the info is out there. Yes the engines have different mechanical limitations, but you can see someone added 10% more duration and the effect it had over stock, or ICL or LSA or LIFT or overlap, and get a general understanding on what these specs do and stumble your way through specing your own, if your hellbent on doing it yourself.

OK that makes sense.   My issue is the last guys to work on V12's seriously were doing it back in the 1980's .  They were working with special heads  that just aren't available anymore.  I've got the 1970's version of heads they were patterned after  but  my ports just can't go as large or straight  as those special heads did.  Plus those special heads somehow accommodate another .100 lift 

In reply to frenchyd :

They didn't just somehow accommodate another .100 lift. That had raised cam towers so that the cams could run more lift.

It's easy to get the perfect cams for a given engine configuration, you just grab them from atop the pile of camshafts that didn't work.  Easy no?  In all seriousness, look, for example, at comp cams lobe catalog (with available core listings including VW 1.5/1.8 SOHC!!??) which is like 150 pages of different profiles.  The 'perfect' pair of profiles is probably in there somewhere, but who's paying for this development program?

If a place like this: http://aj6engineering.co.uk/camshafts/ doesn't have what you want, then I would assume nothing is available and move on.  

An aside, I had no idea the bore spacing and stroke allowance was so huge on these V12's.  The above linked company says that with bespoke liners and a billet crank (and 'related' haha) and no cylinder spacers you can get a bore x stroke of 96.0 x 84.0 = 7.2L or 439 cubic inch!  Even with a 'lowly' 2 valve head, that could be fun!

Javelin said:

In reply to frenchyd :

You still don't understand camshafts. Nobody here is trying to "gotcha", we're trying to help, but you don't read anything or understand more than just the barest of concepts.

Camshafts for n/a (vintage racing) and turbochargers are at direct odds to one another, period. Pick one or leave the stock cams in it. I still don't know how you intend on making cam blanks or will get anything like what you're dreaming of in budget.

If you read everything posted here you'd see that the challenge based engine is going down pretty close to stock  except for the  turbo's.    To stay under the budget it's going to be pretty basic. 
  My concern about camshafts is when the  car comes home and I use it doing wheel to wheel  Vintage racing.  
  Turbo's aren't allowed.  But I won't have the budget limitation the challenge presents. ( my only limitation is what a semi retired guy can justify spending).  
      Kent Cams in England has a billet for a little less than £2000  but once air freight, import duty, exchange rates etc I'd have to justify $3000.   I can have  Crower or Isky regrind  my cams for about $500   But accept less than .500 lift when most guys are at .700 + lift and a lot more duration.   If I grab a Chunk of steel, turn it into a pair of blanks and have My cams ground locally.   I can probably  get it done for less than 1/2 of what Kent gets.    But at this point I don't know enough to go that way.  
      

Stampie said:

In reply to frenchyd :

They didn't just somehow accommodate another .100 lift. That had raised cam towers so that the cams could run more lift.

That would sure be the easy way . Darn I wish I could transfer pictures to show what I mean.  The Jaguar cam towers are part of the cam followers.  And it's a simple block of aluminum. Brilliant in its simplicity.  ( and built on the same tooling that Jaguar used starting after WW2 ) 

   But another .100 would be painfully obvious.  Not to mention longer cam chains.  

grpb said:

It's easy to get the perfect cams for a given engine configuration, you just grab them from atop the pile of camshafts that didn't work.  Easy no?  In all seriousness, look, for example, at comp cams lobe catalog (with available core listings including VW 1.5/1.8 SOHC!!??) which is like 150 pages of different profiles.  The 'perfect' pair of profiles is probably in there somewhere, but who's paying for this development program?

If a place like this: http://aj6engineering.co.uk/camshafts/ doesn't have what you want, then I would assume nothing is available and move on.  

An aside, I had no idea the bore spacing and stroke allowance was so huge on these V12's.  The above linked company says that with bespoke liners and a billet crank (and 'related' haha) and no cylinder spacers you can get a bore x stroke of 96.0 x 84.0 = 7.2L or 439 cubic inch!  Even with a 'lowly' 2 valve head, that could be fun!

Actually over 10 liters. ( with spacer plates)  has already been done. 
    Sir William ( Lyons)  designed it to go over 500 cubic inches without have to change the cores    You don't need a new crankshaft to massively increase  the size.  I offset ground my XKE and gained .400 stroke by reducing the rod journals from 2.300 to Chevy's 2.100  the stock crankshaft is a EN 40 Forging that once machine work is done it's hardened.   Stock crank weighs a whooping 78.8 pounds. 
   plus the block is not a casting.  It's die cast to eliminate air pockets etc. 

   By the way. Jaguar built a few 4 valve heads  for that engine.  It doesn't add enough power to make it worth while.  They race tested it using Group 44's chassis ( without asking them ) 
   Those Heron heads flow way better than any 2 valve head has a right to. If you are interested I'll explain why.  

    
    Oh I forgot to respond to your point regarding camshaft profiles. Thanks for listing that. It will dramatically help. 
  Anyway I've got a computer program where if I accurately enter  the Jaguar data. And punch in each one of those profiles it will tell me exactly what sort of power it will make.  
 Yes it's a massive amount of work.  But you've given me the answer. 
Thank you so very much !!!!!!! 

Paul_VR6 (Forum Supporter) said:

mke said:

I'm almost scared to ask this question but are they the right sizes for your application? Do you have flow curves or know where to find them?

They are in the general range of acceptability, considering.

Please give me your opinion.  I don't know if there is any actual way to determine this  but Jaguar made basically 2 different V12's. The early one with heron heads that flow great but have low compression  and the later HE ( smog) heads that flow less but have high compression. 
      Remembering challenge budget. Which would you run in the challenge the high flowing low (7.8-1) compression. 
 Or the lower flowing  high compression. (11.5-1) 

 both made the same power. 
 The high flowing had 38 degree of timing while the low flowing had 8 degrees yep, 38 & 8  

  I have both. 

frenchyd said:

      Remembering challenge budget. Which would you run in the challenge the high flowing low (7.8-1) compression. 
 Or the lower flowing  high compression. (11.5-1) 

For turbo high flow, low CR, no question will make much more power.

When its time for NA, use the high flow heads with new piston to bump up the CR. 

Take your low flow heads and see what they are worth on ebay as they have no place in a perfomance engine.

Back to cams....valve lift is tied to the head flow curve.  Here's mine (@10" h2o), there is little  gain after about 0.375 on the intake or really 0.250 on the exhaust

So the job of the cam is to get the valve open to the 0.375/0.250 as quickly as possible so the valve spends as much of the duration time near its max flow.   The lobes I chose look like this with stock and another option on there to compare

They open further than needed but that was the easiest way to get quickly to max flow.  another option is a flatter profile on top that limits max lift while keeping the ramps about the same.  

Now look at the stock intake flow....completely flat above 0.250 lift.  The factory cams open the valves to .305 so well past where lift stops helping....almost like the heads and cams where made for each other.  

Designing the cam needs to start with having the head flow data.  There is no other way and this is what any cam grinder will ask for.  There is really no point in throwing around cam numbers until you get the flow numbers.

In reply to mke :

 I think you are right because boost can make up for compression. ( I think).?

  But with E85  I thought if carbureted I could advance the timing and be ahead.     
    Remembering they both have the same net power.