In reply to CatDaddy :
Iron block? Please tell that to top fuel dragsters who all use aluminum blocks.
In reply to CatDaddy :
Iron block? Please tell that to top fuel dragsters who all use aluminum blocks.
In reply to Paul_VR6 (Forum Supporter) :
The other less than ideal is the runner lengths being drastically different. But I'd say the Pent roof is a massive improvement over the 2 valve head.
In reply to frenchyd :
Iron blocks flex less and therefore make more power than the equivalent aluminum block. Aluminum's advantage is weight...that is why its so widely used...not for outright strength. Want both? Compacted Graphite block $$$$$
Fun fact...Go take an inside mic and set it to the inside of the cylinder bore so that it just hangs there in a block going inline with the other cylinders....On a SBC for example. Then push on the block in the lifter valley area and you will flex the block enough for that inside mic to fall out!
Blocks Flex. Now think about how much its moving when running???
frenchyd said:asphalt_gundam said:Need for drastic amounts of timing is a sign of poor combustion performance. Anything of 36 is above average. The required reduction in timing is also a red flag for the newer head.
Swirl/flow at the cylinder wall is another problem. It can't flow through the wall and more importantly it can cause fuel wash leading to ring wear and poor combustion.
Valves are exactly flat to the pistons??? This causes harmonic problems in the valve train too as the vibrations of the piston movement can travel directly into the valve.
Have any pics of these heads?
My guess is some deliberate shape changes by porting (ports and chamber) along with possible valve shape change can fix/significantly improve the newer head to perform. Limiting factors being casting thickness and overall design.
Yes, I'll try to get to them tonight. I've been moving stuff trying to clear out a space to work on the Jaguar .
But I've got to move about 20 things to find space to store one.
As far as fuel wash it really isn't an issue. The piston squish prevents that. I've pulled engines apart with well over 100,000 miles on them and there is no measurable wear!!!! You can still see honing marks in the cylinder wall.
The combustion chamber is in the piston not the head. The head is completely flat. In fact the valves sit on top of the head surface. You can see how free air flows from the intake valve. Without the intake valve in place you can see how the port swirls the intake around the cylinder wall.
The valves don't exhibit any issue with float or harmonics up to about 8300 rpm. That's because the cam activates the valve directly with a simple cup shape lifter to open the valves. No push rods, no rocker arms, and relatively light supple springs. 8300 RPM before float.
the newest design. The HE heads with the combustion chamber in the head are limited to about 450 horsepower ( Net DIN) yet the oldest design made 815 horsepower on 87 octane French pump gas for the 24 hours of LeMans.
Excuse the lousy photos. Dark corner of the shop where storage is. That pair of heads came off an engine 30+ years ago and has never been cleaned.
One of the cheap tricks with The Jaguar V12 is how cheap and easy it is to increase the engine size.
Because the rod journals are 2.30 and the stroke is so short (2.75) if you offset grind the crankshaft to chevy small block size (2.10) you pick up .400 stroke for the cost of grinding the crankshaft. Then you buy Chevy 283 pistons. (3.75 stock Jag is 3.50 ) And get aftermarket 6.00 Chevy rods. For about $1000 you increase the engine from 326 cu in to 418 cu in.
If the cylinders are in that good of shape then I fuel wash is clearly not a problem. Given the timing requirements and the small bore size I still suspect poor fuel atomization or distribution/mixing in the cylinder. Could be the spark plug placement vs wet flow characteristics too.
The stroker crank is a great idea and you'd be surprised how much lighter everything can get if you go that route. Given the small pistons I'd even look at .780 or .840 wrist pins and custom pistons to lighten even more but the cost will go up some.
What exactly "limits" the HE head to 450hp? Or was that all the factory ever tuned them to?
More on the combustion chamber head vs. piston designs. On the Tractor pull Diesel heads I built it is a HUGE power increase to machine a combustion chamber into the head. Helps flow a little but the biggest gain is in efficiency of the combustion. Makes more power despite the compression drop (but the 100lbs of boost helps).
If the Jag v12 early head has the room to put even a 1/8" deep combustion chamber in it by sinking the valves and shaping a chamber it will be better. Pictures i'm finding of the HE head appear to show the goofy sunk exhaust valve like IH did on their engines back in the Scout years. Its not a great design, but again is there is room/material in the head I'd spend time reshaping the chamber to a much better design. I'm finding enough pics to see that it has been done before.
frenchyd said:In reply to CatDaddy :
Iron block? Please tell that to top fuel dragsters who all use aluminum blocks.
What they don't have is water jackets.
The liners are also slip-fit to make between-round engine rebuilds easier.
asphalt_gundam said:Fun fact...Go take an inside mic and set it to the inside of the cylinder bore so that it just hangs there in a block going inline with the other cylinders....On a SBC for example. Then push on the block in the lifter valley area and you will flex the block enough for that inside mic to fall out!
Blocks Flex. Now think about how much its moving when running???
You can measure the bore distortion in the main journals from installing the intake manifold, too.
In that light, the Chevy "no torque" intake gaskets make sense. They aren't wedging the block apart. They fail a lot, mind you, but they keep block distortion down so they could limp a 50s engine past 90s emissions requirements.
Pete. (l33t FS) said:frenchyd said:In reply to CatDaddy :
Iron block? Please tell that to top fuel dragsters who all use aluminum blocks.
What they don't have is water jackets.
The liners are also slip-fit to make between-round engine rebuilds easier.
Hmmm so does Jaguar. No deck plate because the block is pressure die cast but the liners have a step on them to prevent rocking. It's really very brilliant. The head acts as the deck to retain coolant. But because there are so many studs it's extremely rare for a Jaguar to loose a head gasket.
look at the pictures I posted earlier of the block and check out the head.
In reply to frenchyd :
The difference is the Top Fuel block full supports that slip in liner unlike the Jag. The Jag design works up to a point. The B series Honda is also has a similar design style and those need more support after power has been increased. The Jag's advantage is shorter cylinders and ideally thicker sleeves. I've done several early Ferrari blocks and I think one Jag way back and the design is ok but from a race/high performance stand point in regards to cylinder stability its not great. All those V12s I worked on got much thicker LA Sleeves installed to help with this. If going for an all out max effort build a cnc machined deck plate fit to a cnc machined block opening would be the way to go. Much like the B series Honda and Subaru EJ engine upgrades which are absolutely required on those for any big power engines.
Cylinder stability not only affects the head gasket seal it also greatly affects: Ring seal, ring/cylinder wear, piston skirt wear, stress in the block (that often cracks a block when a cylinder is poorly supported), the overall strength of the block, and engine cooling.
That cylinder step isn't to prevent rocking of the cylinder BTW. Its to make sure that the head sandwiches the cylinder in the block and the cylinder doesn't work its way down which would blow the head gasket and in a really bad case contact the crank.
In reply to asphalt_gundam :
No a Jaguar won't make 9000+ horsepower like a top fuel and since they run more than a 1/4 of a mile before rebuilds they need coolant.
The sleeve is very thick which adds greatly to the reason Jaguars are so heavy. I can increase the bore by a 1/4 of an inch and still have .125 wall thickness ( on the part surrounded by the block). The part that is in the coolant is much thicker. I'm guessing because I don't have a sleeve handy but I suspect it's between 3/8 & 1/2 inch thick. Over the block. Then at the top the flange adds another 1/4 inch.
Jaguar won the 24 hours of LeMans ( twice) with those sleeves bored out and never had an issue blowing head gaskets. 815 horsepower on French pump grade gasoline.
In reply to frenchyd :
Damn, that sleeve is thick. In which case I'm not surprised it has no problems. That is significantly thicker than any v12 sleeve I've worked with and I'm assuming that it's also a much shorter cylinder than the Honda or Subaru too.
frenchyd said:Pete. (l33t FS) said:frenchyd said:In reply to CatDaddy :
Iron block? Please tell that to top fuel dragsters who all use aluminum blocks.
What they don't have is water jackets.
The liners are also slip-fit to make between-round engine rebuilds easier.
Hmmm so does Jaguar. No deck plate because the block is pressure die cast but the liners have a step on them to prevent rocking. It's really very brilliant. The head acts as the deck to retain coolant. But because there are so many studs it's extremely rare for a Jaguar to loose a head gasket.
look at the pictures I posted earlier of the block and check out the head.
It is generally not a good thing to have features in common with an engine that is expected to run in the hundreds of revolutions before it needs to be rebuilt. 
I think you're mixing up liners and sleeves. Or maybe I am. Anyway, the TF blocks have a slip fit iron (steel?) liner in a solid aluminum block.
In reply to Pete. (l33t FS) :
Jaguar has a slip fit liner/ sleeve? You'd think they were cast iron but they wear like steel. Honest, normal to not have any measurable bore wear at 100,000 miles
The block is solid die pressure cast.. So no porosity, voids, or pockets. Not the typical sand casting.
In reply to frenchyd :
That block is a tank! Other than the condition and quality of the studs I wouldn't worry about throwing power at it. Between those thick cylinder sleeves and 6 studs per cylinder its no wonder they don't have head gasket problems.
I'd say your biggest problem is going to be the machining. Line hone shouldn't be a problem. Sleeves out the block gets decked, then sleeve installed and they get decked to .001-.003 taller than the block (at least that is how all the other blocks I've done like this are). Torque plate to hone with. If the block has almost no bottom clearance to the mains then its much easier to hone strait with 1/2 length stones or diamonds.
In reply to frenchyd :
That isn't a solid block, it has water jackets.
I don't know how heavy a TF block is, but I had to grunt a solid aluminum SBC block around a shop once. Need all the beef when the blower is cramming 60psi into the engine. I dunno how much power it made, but the dragster ran mid 5s at 250...
asphalt_gundam said:That block is a tank! Other than the condition and quality of the studs I wouldn't worry about throwing power at it. Between those thick cylinder sleeves and 6 studs per cylinder its no wonder they don't have head gasket problems.
I'd say your biggest problem is going to be the machining. Line hone shouldn't be a problem. Sleeves out the block gets decked, then sleeve installed and they get decked to .001-.003 taller than the block (at least that is how all the other blocks I've done like this are). Torque plate to hone with. If the block has almost no bottom clearance to the mains then its much easier to hone strait with 1/2 length stones or diamonds.
I made my own deck plate for it. Because I bore the sleeve in a lathe and then slide them in the block to finish hone to size. Sir Lyons designed that block to go out to 500 cu in. It will cost about $1000 to go to 418 cu in
asphalt_gundam said:In reply to Paul_VR6 (Forum Supporter) :
The other less than ideal is the runner lengths being drastically different. But I'd say the Pent roof is a massive improvement over the 2 valve head.
That can easily be fixed with careful manifold planning.
Pete. (l33t FS) said:In reply to frenchyd :
That isn't a solid block, it has water jackets.
I don't know how heavy a TF block is, but I had to grunt a solid aluminum SBC block around a shop once. Need all the beef when the blower is cramming 60psi into the engine. I dunno how much power it made, but the dragster ran mid 5s at 250...
Actually there are no jackets. There may be space where water can be around the cylinders but with no deck surface technically there aren't any "jackets". And to be fair a top fuel engine has heads made from billet aluminum. While the Jaguar head actually is an aluminum casting. ( with water jackets ).
However I will give you full credit a top fuel engine is made from billet aluminum. Not a casting.
However the Jaguar block is die formed. Aluminum under pressure is pressed into a form.
Strength wise it's between a billet and a casting. Closer to the billet.
I found out, through a third party. 2600hp, from an engine that was loosely based on a small block Chevy.
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