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frenchyd
frenchyd MegaDork
5/11/22 10:19 a.m.

They aren't allowed.  Nothing after 1972. Plus they wouldn't make enough power. 
 

basically to run at the pointy end of group 6 you need 80+ hp per cylinder. 
 While I only need 54+ hp. 

bobzilla
bobzilla MegaDork
5/11/22 10:28 a.m.

Considering turbo 4.8's can make a reliable 650hp, I think that's enough.Not like it's ever getting built anyway.

rslifkin
rslifkin UberDork
5/11/22 10:36 a.m.

I guess the big question is this: what's the end goal to be accomplished by revving it higher?  Are you just looking for more power, or?

84FSP
84FSP UberDork
5/11/22 12:23 p.m.

At least on the mechanical side I would think a balance and blueprint is key to reducing harmonics and mechanical stresses.  The valve train control does seem to be the thing most folks run into first.  The LS high RPM guys all seem to choose the shaft mount rocket setup in order to control valve float.  One would think this is simply a longer shaft setup?

frenchyd
frenchyd MegaDork
5/11/22 12:29 p.m.
84FSP said:

At least on the mechanical side I would think a balance and blueprint is key to reducing harmonics and mechanical stresses.  The valve train control does seem to be the thing most folks run into first.  The LS high RPM guys all seem to choose the shaft mount rocket setup in order to control valve float.  One would think this is simply a longer shaft setup?

I don't have pushrods or rocker arms.  The "lifter" I use is a light thin cup directly over the valve. Transferring the lobe action directly on the valve stem. 
    Now NASCAR somehow gets all that weight and friction to work at near 10,000 rpm but that's why those engines cost nearly $100,000 each.  
    The V8 suffers  from 2nd order harmonics  while my engine does not have any unbalanced loads or harmonics.  In fact properly tuned a coin can be balanced on the engine while running.  

yupididit
yupididit GRM+ Memberand PowerDork
5/11/22 12:48 p.m.

In reply to frenchyd :

The coin trick doesn't mean much. There are v8's that do that from the factory. 

 

Anyway what are you going to do with this engine and what is your budget? 

frenchyd
frenchyd MegaDork
5/11/22 1:03 p.m.
rslifkin said:

I guess the big question is this: what's the end goal to be accomplished by revving it higher?  Are you just looking for more power, or?

Absolutely, more power.  No, I'm not in love with higher revs. So there is no magic at 10,000.   I do know the factory ran  it to 8300 rpm ( just short of valve float ) for 3 hours. In stock configuration. 
  But I'll be racing guys who think nothing of dropping $20,000+ on their engines.  
  They make 80+ horsepower per cylinder  while I only need 54 horsepower per cylinder  to stay with them. 

frenchyd
frenchyd MegaDork
5/11/22 1:19 p.m.
yupididit said:

In reply to frenchyd :

The coin trick doesn't mean much. There at v8's that do that from the factory. 

 

Anyway what are you going to do with this engine and what is your budget? 

Race with SVRA in group 6.   My budget, is definitely past the challenge budget limits.   But I won't waste money for nominal increase in power. 
    The guys at the pointy end of group 6 are making about 80 hp per cylinder. While I only need to make 54. But that will take slightly more than twice the stock horsepower. Getting to 80% of that is very straight forward. But I'm not using the engine fully. That short stroke can be a benefit as well as a curse.  With a 3&1/2 inch stroke like a small block Chevy I'd be over 454 cubic inches.  On the other hand I'm not as restricted RPM wise.  

     The dry sump system is a given while autocross doesn't need it, they aren't braking hard enough to feel their eyeballs want to pull loose from their sockets  from 150mph down to 40 or  going into 270 degree corners.   that's going to be $2000 or a little less depending on if I can find good used pieces. 
  Cams could run over a grand if I need new ones made. And pistons?   Well that's probably around $100 each. 
  Valves could cost $50 each for the really good ones. If I need titanium retainers that's another $50. 
 

wspohn
wspohn SuperDork
5/12/22 11:38 a.m.

Weak spots will definitely be either valve gear (which it sounds like you have a handle on) or durability of the bottom end, which the dry sump helps - are the cranks strong enough or would you need a custom race crank?

We've come a long way - my 1958 race car engine red lines at 7900 rpm and has 12:1 compression. My 2007 street car engine (both with fairly long strokes) red lines at the same rpm and has 11.5 compression.

If you could only make a fibreglass shell of the V12 engine and put two S2000 engines with turbos under there, you'd be right on 800 whp.....

rslifkin
rslifkin UberDork
5/12/22 12:26 p.m.

Being that your primary goal is power, is boost an option?  Adding boost and keeping the RPM reasonable may save you from having to go crazy with custom cams and figuring out what kind of oiling and valvetrain mods will be needed to survive long term at significantly higher RPM.  Plus, provided the bottom end is stout enough (other than maybe pistons there's a good chance it is) that should make your power goal attainable.  

APEowner
APEowner GRM+ Memberand SuperDork
5/12/22 12:42 p.m.

Assuming the bottom end will hold together (and based on what little I know about the Jag v12 I think it will) then everything that improves airflow matters.  Intake, exhaust, intake an exhaust ports, valve and seat shapes, valve lift, duration and timing.  It all matters. 

As far as getting it to spin faster is concerned; lobe profile and spring pressure are the big factors.  With the cams directly over the valves you're going  to be limited in lift unless you modify the head to move the cams further away from the valves.  Do you know what the max lift that you can achieve before coil bind is?   You've ported and flowed these heads before.  Do you have actual numbers?

 

frenchyd
frenchyd MegaDork
5/12/22 12:52 p.m.

In reply to rslifkin :

I'm really sorry boost is not an option. I sure wish it was.  Then I could go after the Corvette big blocks racing with 800 hp.  But SVRA won't allow it.  
  But valve train mods won't be needed other than maybe springs and lighter valves.  If I go that way the  valves are big enough to give a 20% increase in flow plus whatever I can pick up from port work. 
   I may be able to avoid new pistons.  And still get 13-1 compression. Maybe even 14-1.   That kinda restricts me to 8500 RPM Unless I want to risk it.  ( the factory tested at 8300 for 3 hours) 

Stampie
Stampie GRM+ Memberand MegaDork
5/12/22 2:00 p.m.

In reply to frenchyd :

I'd love to read more about how the factory tested it to 8300 rpm for three hours. Could you give me a reference so that I can read about it?

frenchyd
frenchyd MegaDork
5/12/22 3:48 p.m.

In reply to Stampie :

I'm away from my library right now but if you go to AJ6 engineering on the internet then scroll through to the V12 history  you'll have a good shot at finding it. 
  It will also explain a lot of the things I've been saying.  Both good and bad.  
    

Stampie
Stampie GRM+ Memberand MegaDork
5/12/22 8:12 p.m.

In reply to frenchyd :

Can you link me?  Go there, click in your address bar, hit CTRL C for copy, then come here and hit CTRL V for paste.

frenchyd
frenchyd MegaDork
5/12/22 8:51 p.m.

In reply to Stampie :

Sorry, I can understand coming from a world of lifters, push rods rocker arms in truck engines  the revs of a direct acting Overhead cam  short stroke engine must be astonishing for you.   
     I thought the Article in AJ6 would still be there  but it's not.  
 I'll have to find it elsewhere.   I've plenty of resources but it's a slow process  

 

Racingsnake
Racingsnake Reader
5/12/22 9:23 p.m.

There doesn't seem to be anything on the AJ6 site about testing the V12 to 8300 rpm

yupididit
yupididit GRM+ Memberand PowerDork
5/13/22 7:12 a.m.

I just read the whole website and couldn't find it 

frenchyd
frenchyd MegaDork
5/13/22 8:46 a.m.

In reply to yupididit :

Interesting read wasn't it.  I just looked at the site. It has less about the development then it used to but more about other things.  the owner of the company started with the Jaguar factory  and really knows his stuff. If you want your ECU rebuilt he's the guy.   He's actually older than I am so I don't know how much longer.   
   Anyway there is a video done by the factory with the designers I'll see if I can find  it on the Internet but if not I've got a library with plenty of sources.  
      
 

yupididit
yupididit GRM+ Memberand PowerDork
5/13/22 10:05 a.m.

In reply to frenchyd :

I wouldn't call it interesting since I was reading to find particular information. 

Stampie
Stampie GRM+ Memberand MegaDork
5/13/22 10:14 a.m.
frenchyd said:

In reply to Stampie :

Sorry, I can understand coming from a world of lifters, push rods rocker arms in truck engines  the revs of a direct acting Overhead cam  short stroke engine must be astonishing for you.   
     I thought the Article in AJ6 would still be there  but it's not.  
 I'll have to find it elsewhere.   I've plenty of resources but it's a slow process  

 

What world are you talking about?  You mean my world where my first job out of high school was at an independent Volvo shop?  Or where I owned all OHC engines up until 2008?  I guess I forgot all that stuff at that point.  Also why would you go back and edit a post a day later to say something totally different?  Still would love a reference to your "facts" because otherwise you just sound like the kid in elementary school claiming his dad is an astronaut.

Slippery
Slippery GRM+ Memberand PowerDork
5/13/22 10:25 a.m.
yupididit said:

I just read the whole website and couldn't find it 

Is this what you guys are looking for? I did not even read it just quickly looked for the rpms ... but there were missing, always love these threads lol

Jaguar V12 development article

Click through the pages at the bottom.

yupididit
yupididit GRM+ Memberand PowerDork
5/13/22 10:43 a.m.

In reply to Slippery :

I ain't reading all that lol

Stampie
Stampie GRM+ Memberand MegaDork
5/13/22 10:53 a.m.

In reply to yupididit :

I just searched all those pages for 8300 and it wasn't on any of them.

Slippery
Slippery GRM+ Memberand PowerDork
5/13/22 10:59 a.m.
yupididit said:

In reply to Slippery :

I ain't reading all that lol

I searched it and nothing wink

Frenchy, are you Mguar on the jag forums?

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