Which head/ engine design?

Both are OHC 2 valve designs. Both designs make the same  power. Both will be for racing only and are budget limited. 
      The first is Heron head design.  Brief review, totally flat head combustion chamber in a perfect Hemi chamber in the piston. Valve opens and incoming charge goes all the way to the cylinder walls without obstruction or turning( which reduces flow)  design used by Coventry Climax  and others.  7.8-1 compression ratio. 38 BTDC  timing.  Spark plug center of combustion chamber. milling head does not increase compression. 

 Second is Fireball head Designed by Buick in the 1920's and used by Chevy through the 1960's in their 6 cylinder. Combustion chamber in head  designed to swirl  fuel charge over hot exhaust  prior  combustion.  Flat topped piston right to top of bore. Doesn't  flow nearly as well due to turns required to shape the flow over exhaust valve.  About 10% better fuel mileage ( and lower emissions).  11.5-1 compression ratio.  17 BTDC Milling head increases compression ratio. But limited due to chain drive ( OHC )  
      
    You could  increase flow by opening the combustion chamber but that would reduce compression.  Each point of compression is worth a 4% increase in power. 

No can't swap pistons. Because, ••• Clang.
    New pistons are around $2000 ( with rings and pins.    Unless I can find some 3.655-3.545 bore pistons with the right pin height. 1.255 pin size  .9375 & a bowl shaped combustion chamber.  For less. 
   
 

Both horrible, antique designs, easily outpaced by any lawn mower built in the last twenty years.

Naturally aspirated or are you going to boost it?

Streetwiseguy said:

Both horrible, antique designs, easily outpaced by any lawn mower built in the last twenty years.

Considering it was originally designed in 1954, built in 1966 and first sold in 1971. Yes you're right. But you don't need the latest thing to have fun Vintage racing. 
     Plus they are solid, powerful smooth engines. Making more power than a Chevy 454. 
     My question was use the head with better flow potential or higher compression? 

APEowner said:

Naturally aspirated or are you going to boost it?

Naturally aspirated. In fact to run in group 6 I need to use carburetors 

I don't know much about either head but if there was a reliability and/or parts availability advantage I would be looking at that as well when making a choice.  

frenchyd said:

 Making more power than a Chevy 454. 
 

Come on now.  I thought we agreed that you were wrong on this point.

Same parts different castings. 
  One flows great and has made over 800 horsepower for 24 hours on French pump gas.  
    The other has the same horsepower to start but only uses 17 degrees of timing.  I'm thinking E85 with its over 110 octane  rating I'm thinking might allow more advance and more power. 

Stampie said:

frenchyd said:

 Making more power than a Chevy 454. 
 

Come on now.  I thought we agreed that you were wrong on this point.

His dig he couldn't leave out is totally irrelevant, so I'm gonna just ignore it!

As to the question, since it has to be naturally aspirated, I would think the higher compression, with some blending / SUPER mild reshaping for a bit more flow. I think that would build more power (all else equal) than trying to get higher static compression from the Heron head / piston. This also assumes you will be running fuel that will tolerate the high compression. And assume the cam profile is aright for the application.

Stampie said:

frenchyd said:

 Making more power than a Chevy 454. 
 

Come on now.  I thought we agreed that you were wrong on this point.

What I agreed was Chevy rated the rare L88 version made more Gross horsepower than  Jaguar made Net horsepower. 
     Since the L88 was never made once the Use of Net ratings were standardized  I'm forced to admit that those Gross numbers are bigger than the Net numbers used by Jaguar. 

In reply to 03Panther :

That's my thoughts as well. I'm thinking I can mill the heads .010 to pick up some compression.  Maybe just remove some of the more acute edges.  
    The stock cams are very mild .375 lift ( at the valve).  250 duration.   They no longer sell a billet with more lift and duration so I'll just have it locally reground. 
  So same cams for both heads. 
     More compression for the Heron heads will force me to buy new pistons. @$2,000 

In reply to frenchyd :

I'll let you get back to your regularly scheduled delusion.

In reply to Stampie :

I notice you didn't have a comment regarding the L88Corvette ( 1968 ) vs the   230 hp 1986 C4 in Road and Track.  

Are we going to have to more "scientific" testing in Assetto Corsa again?  

It's been done. Way back in 1986 .  

frenchyd said:

It's been done. Way back in 1986 .  

Heron setups are garbage, you need a massively high port for them to work and really good short turn. Usually they won't because it's all for packaging. I hold out for pics or a port diagram from the side, but my vote is literally any chamber other than Huron (I also don't like hemi chambers, fight me)

If you're going with e85 I'd go with the high compression heads. Also more fuel efficient means that you carry less fuel during a race and that is less weight. Fuel also sloshes and changes weight during the course of the race which creates it's own problems. Less fuel = a good thing. 

I do understand that e85 doesn't really mean less fuel than 93 e10. But I assume you want to run e85 in either setup. 

Right, E85 will yield more power as tested by GRM.  But when added to high compression engines power increase goes up. And I suspect I can add advance to gain even more power.  That engine has only a total of 17 degrees advance. Whereas the way it was originally designed it was set up with 38 degree total. 
   However the flow out of an HE engine sort of cuts off power increases above 450hp regardless of what is done. ( short of re-engineering the whole combustion chamber). 
     The low compression engine ( 7.8-1 compared to 11.5-1 ) flows like gangbusters. With decent compression ratio 6-700 horsepower is achievable.  And the pistons can add up to an additional 40 cu in  for the same cost.  But that's $2000 ( for 12 w/ pins and rings) unless I can find production pistons from something that will work. 
      I'm not too worried about fuel mileage.  With gas, typical mileage during a race is going to be around 6-8 mpg.  So if I get 3- 6 mpg with E85.  Worst case I'll come back in with 6-12 gallons left in the fuel cell after the race. That's at Elkhart Lake with its 4 mile long track and 3 long straights.  Shorter tracks with less straights fuel mileage  will go up.  

During GRM's test of E85 they gained 10% on a 9.0-1 compression ratio .  So 11.5-1 compression should gain  2% more?  And being able to advance timing  to around 38 degrees from the 17 it is currently should gain even more.  
     The factory set the timing at a total of 17 degrees based on premium being 91 octane in most places here in the  US. Since octane rating of racing E85 is around 100+. Timing should be good for another 10+ degrees?  Quick and dirty that should get me another 10% power gain. 
    Starting out at 262 horsepower. Cams should add at least 100 considering how mild the stock cams are.  Adding cold air intake has been documented to gain 30 horsepower and eliminating mufflers etc is another 20 horsepower 12% more for E85, 10% for added timing.  That gets me around 425 horsepower.   

Are the euro 9:1 pistons unobtanium on the used market?

I have had three sets of 9.0-1 compression V12's over the past 50 years I've owned V12's  ( I once had 50 V12's in my shop ). But sold most to the scrap metal dealer  back in 2000.    
       The first year (1971-72 ) most Non - Californian V12 Jaguars were 9.0-1.  (The  market value of XJS's in Europe is now so high,  many American spec cars are heading to Europe). 
      But I understand the power increase.  299 hp vs 262.  And the 1980 10.0-1 compression EU spec had an additional 15 horsepower over that 

  Realize that only slightly over 4700 EU spec XJS were made before 1981 and the HE.  This was the peak of the labor strikes and Jaguar came very close to closing.  They were losing as much as £50 million a year ( about $40 million). Only building 30,000 cars annually. The XJS was never accepted as a replacement for the XKE and most V12 buyers were waiting for the coming XKF 
    Cost cutting was the God of BLMH  so instead of improving quality they went for cheaper and  faster with the result £20,000+ cars were delivered with antennas that wouldn't go down and if they did manage to go down they failed to go up.  Electrical connections were lose, so problems would be intermittent. Supplies sold them fuel lines that were not capable of delivering fuel reliably.  Bodies were delivered with such poor quality control that 2 different sized windshields and 4 sized rubber gaskets were required for the same car.  The new paint method Jaguar bought from GM wound up melted the lead used to correct the flaws generated in stamping.  Forcing only  4 colors to be painted. Some cars required as many as 4 redo's in order to get the paint done without melting the lead. ( Jaguar was using lead back then instead of Bondo). 
Any profit that Jaguar managed to scrape out BLMH took to reward their management team. 
    BLMH  had Jaguar on the chopping block  and Only John Egan taking them independent  and doubling production  to 60,000 cars while improving quality saved them. 

I recently thought I bought a EU spec (9.0-1 compression pistons ) Right hand drive, car for $1000.  Only to have him keep it for another year and sell it for $800 more than I'd offered. 
     Every once in a while Cosworth runs a new set of forgings.  What is so desirable is even though they are forged. They are as light as the stock cast Brico pistons. Plus the combustion chamber shape is the best design for the early Heron Head engine.   That design is worth 55 horsepower over the normal bowl shape with the same compression 
     
    

I had a whole thing typed and I lost it. You will gain more with high comp if you are knock limited, and that can be quite a bit. Just set the timing for what the motor likes, it is what it is 20, 22, 35, 45.. this is what the dyno helps with or what the drag strips helps to figure out. 

Not sure about 100 for cams and 30 for air intake, we see maybe 10whp from streetable cams and -5 to 5whp from intake at the worst spot in the curve (usually past peak hp)

In reply to Paul_VR6 (Forum Supporter) :

The stock cams only lift the valve .375 off the seat. And duration is modest. For racing the cams can be ground to produce .450 lift and 300 degrees duration. While the billets were over .510 before coil bind. The nice thing is valve float doesn't occur until 8300 RPM. 
    If you look at the power curve with the stock cam it starts to fall off at 5500 rpm. (Jaguar cams are designed for big heavy sedans driven by  older guys ) Everything was traded for smooth and quiet. The con rods have great big weight pads top and bottom ( almost a pound total) because the stroke is so short. Because of that there is an extra 20 pounds in the crankshaft. Due to the 78.8 pound crankshaft   The block is covered in bracing add even more weight. All of that because they feared engine noise would bother the fat old men.  There was a guy in Australia who took excess weight out of the engine and saved more than 120 pounds in the engine alone. While bringing the engine up to 426 cu inches. 
 Whereas once you get some lift and duration into it,  it's happy at  7000+ rpm.  Yes that requires some port clean up work but it's not big hog out work. That and with the short stroke 2.75" the piston speed is really modest at that RPM. If I recall correctly something around 2500 fpm 

        I have a nice computer driven program that will help me optimize lift, duration, and lobe center. I did it in the past  for my Racing XKE V12  but I need to go back to refresh my mind to the exact details.  There were some surprises if I remember correctly. Considering Bruce Crower did all the camshaft and head work for Group 44  I do have some excellent notes. 

  Regarding air intake. To eliminate intake sounds the air cleaners  only have a 2 inch opening. Tapering up to 3 inch at the air cleaner.  Eliminate the headlites and put a 5 inch duct to bring in cold fresh to the air cleaners is a big part of that number. The other is  Under hood temps in the Jaguars are really high! So high that the factory had fans for the batteries so they wouldn't melt the lead.  The fuel line was air conditioned ( honestly ) !!!   To prevent fuel boiling in the lines. 
    Since AJ 6 engineering published the 30 and 20 numbers ( he is a retired Jaguar engineer ) and he wasn't selling fresh air kits I accept his numbers.
      Aside from that he has a very strong recommendation from the Jaguar community who do buy his modified ECM. 

The old WW2 designed cast Iron Six was pretty well developed by the time it went out of production in 1987. ( 39 years ) While  the V12 isn't nearly as well developed.  Only produced for 24 years.  In addition only 30,000 cars a year were produced even in good years. Most of those were 6 cylinders. Global production  of the V12. annually was around 2000 or so  late 80's early 90's  it might have gotten to around 4000.  That's in both Srdans and XJS. 
  Conceived to compete with Cadillac's 500 cu in engine when bigger was better. It was design to go to 500+ cu. With attending power increases. 
   It stayed at 326 inches  for over 20 years due to the fuel shortages plus BLMH's mismanagement. 
     Intended to be introduced in the 1960's it was delayed due to failure of the EFI supplier to develop it on time.  A hurried retro fit of carbs hurt power dramatically.  Which in turn hurts XKE sales. Jaguar had wanted 5 years of development of  the XKE V12 before replacing  the E type with the sedan based XJS.  
    The XJS never took off due to fuel shortage and the long awaited XKF  which Jaguar couldn't afford to build due to anticipated banning of convertibles.  ( remember the small volume of cars Jaguar was selling).  
  Buy the early 1980's Jaguar was no longer profitable and losing as much as £50 million a year. To return to profit required sales of 60,000 cars annually.  Just not possible under BLMH management. 
 

     So the potential is great for cheap power in the V12.