XJS ( X27 ) 1975 - 1996 3.6 4.0 5.3 6.0

HE vs flathead and acceptance of boost pressure.

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  #161  
Old 04-30-2020, 11:35 AM
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Alcohol will outcool any intercooler, I've seen alcohol do 90 degree temps whereas a good intercooler only got it down to 120. I'm talking total advance. As far as my 1000hp claim, I've seen e85 make 1.47x the hp 92 could make. Maybe 1000 is too far, at least 900. But no thanks, I couldn't afford that entire situation.
 
  #162  
Old 04-30-2020, 08:54 PM
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Originally Posted by ronbros
MG WTF , .300 ring gap?
I still stand by the fact you need to double the ring end gap if you’re going to turbo any engine. I remember doing that to mine. When I put those two Saab turbo’s. On it.
It’s been bothering me though. So I finally dug up my old notes it’s .015 stock and opened up to .030. Not .150 opened up to .300. Sorry.
 
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  #163  
Old 05-01-2020, 12:26 AM
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.015 is pretty tight even for not having turbos. Just one more thing, ug.
 
  #164  
Old 05-01-2020, 08:25 AM
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Alright! Figured out my ring gap. Going to go to increase it by .002" per many pistons manufacturers. Really wish I didn't have to pull pistons out, but hey, gotta do what you gotta do.

Let's talk head gaskets! What are some good options? Definitely need something thicker to drop compression.

Is it even worth time to maybe port the heads a little at home? Like removing casting flashing?
 
  #165  
Old 05-01-2020, 10:46 AM
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Ivan your building the engine?
just show us all your knowledge, we are waiting?
words, words words, nothing real YET!
you build it and they will come!
 
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  #166  
Old 05-01-2020, 11:46 AM
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Well, by this websites definition of "build". I'm not building it because I'm not going to poor $30k into endless custom parts. Right now I'm putting money together to go and buy a 93 xj12 for it's motor. I do need guidance on where to find some thicker gaskets. I know for sure that I want to do a higher octane tune at some point and push some higher pressures, and it's not knock that compression causes it's just the load it causes on the bottom end. Plus I need insight on how much I should do with the he heads to improve them, if it's worth it at all.
 
  #167  
Old 05-01-2020, 12:36 PM
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Originally Posted by Ivan Hall
.015 is pretty tight even for not having turbos. Just one more thing, ug.
.015 the end gap on pre HE Jaguars
 
  #168  
Old 05-01-2020, 01:05 PM
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Originally Posted by Ivan Hall
Alright! Figured out my ring gap. Going to go to increase it by .002" per many pistons manufacturers. Really wish I didn't have to pull pistons out, but hey, gotta do what you gotta do.

Let's talk head gaskets! What are some good options? Definitely need something thicker to drop compression.

Is it even worth time to maybe port the heads a little at home? Like removing casting flashing?
.002 increase? That’s less than production tolerance on brand a new Jaguar. ( .014- .020 ) Heat will expand the ring. Double the power and you’d better double the gap. .002 isn’t double. Remember you have a slightly over 3& 1/2 inch bore
I suppose piston mfg. would tell you that. They want to sell pistons.

the trouble with thicker head gaskets is that moves the camshaft further away from the crankshaft new chains and sprockets are pretty tight.
Not sure you can put much thicker gaskets on without custom chains and or sprockets.
Thicker gaskets might also move too much and be easier to blow. A lot of the racers went to cooper rings. ( gas filled hollow rings set into a groove cut into the cylinder.

Remember the basic rules. Air has mass. When you force mass to turn you decrease flow.
Look at the flow of the early pre HE head ( also called the Flathead )
and compare it to the flow of the HE
In the Flathead the valve opens up and air swirls (caused by the angle of the intake port. Right into the cylinder as the piston is going down. When the piston comes up on the compression stroke the flat flanges Of the piston forming the combustion chamber ( Huron head) in the piston create squish forcing a turbulent mixture of air and fuel into the center of the cylinder where the spark plug is on the Flathead.

Compare that with the HE head. Open the valve and the air has to curve to get past the recess the intake valve is sitting in. Then as the piston comes up the fuel air mixture is forced over the hot recessed exhaust valve before it can squirt over to the spark plug. That heat will increase the tendency to preignition.
instead of the flame front being centered over the piston it’s focused on one side of the piston. Adding drag and decreasing net horsepower.

Finally the ports are free of casting flash. There is room for opening up the ports and still retaining the angle that gives swirl. But it’s a massive undertaking. Only rarely does hand porting actually increase flow and then only by a very skilled and patient person. I
typically spent 200 hours getting the same flow in all 12 intake ports. since you’re limited by flow from the stock intake manifold 200 hours of work tends to yield very little unless you are using alcohol which increases the fuel mass significantly. ( about 60% more than gasoline if you’re using E 85. ) nearly 100% more if using methane.
If you have a big enough vertical mill you can use a ball mill and at the right angles reduce the porting time down to about 20 hours or so.
 

Last edited by Mguar; 05-01-2020 at 01:23 PM.
  #169  
Old 05-01-2020, 01:55 PM
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Alrighty great then. I have no problems not taking time to port. One thing I'm going to have to stand firm on is my ring gap claim, I'm pretty sure there's more turbo Honda's out there going by that rule that never had Piston gap issues. But I will do some more reading into that, you could be right. Also, I looked at some ignition numbers for other motors, our timing for our cars isn't entirely different. My w8 passat with 10.8:1 was at 25 degrees at wot at redline, so close to the Jag. And as far as head gaskets, I see two different thicknesses, .040" and .060". Which one is stock? And do you have some documents on stock ring gap?
 
  #170  
Old 05-01-2020, 02:00 PM
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This is from total seal.
 
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  #171  
Old 05-01-2020, 02:01 PM
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@Mguar not exactly too far off with your .030" claim lol. Math comes out to .024" for medium boost 15-30psi.
 
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Old 05-01-2020, 03:32 PM
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Originally Posted by Ivan Hall
This is from total seal.
you should buy Total Seal rings , they are much better than factory Jag , they are made for forced induction engines!
i have used them in many engines! MG probably never even held one in his hands!
ron
 

Last edited by ronbros; 05-01-2020 at 03:35 PM.
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  #173  
Old 05-01-2020, 03:52 PM
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Swear to God man if I do all this work just for it to blow up, I don't know what I'll do. I'll be real mad. I'll do total seal. At that, I'll need to research what kind of crosshatch my bore needs to have, because I'll be using a motor with 50k miles. Hopefully I won't need any machine work.
 
  #174  
Old 05-01-2020, 04:58 PM
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Maybe I'll do total seal later. Don't know. https://www.jegs.com/i/Total-Seal/901/S1444/10002/-1

I don't think it's worth it in the short term. Maybe I'll do it later if it holds together. Yeah I'll do total seal after I put some miles on it.
 
  #175  
Old 05-01-2020, 05:00 PM
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Originally Posted by Ivan Hall
Alrighty great then. I have no problems not taking time to port. One thing I'm going to have to stand firm on is my ring gap claim, I'm pretty sure there's more turbo Honda's out there going by that rule that never had Piston gap issues. But I will do some more reading into that, you could be right. Also, I looked at some ignition numbers for other motors, our timing for our cars isn't entirely different. My w8 passat with 10.8:1 was at 25 degrees at wot at redline, so close to the Jag. And as far as head gaskets, I see two different thicknesses, .040" and .060". Which one is stock? And do you have some documents on stock ring gap?
Static timing on a Flathead is 10 degrees at idle and 38 at 3000 RPM. I’ve run it up to 40 degrees with a little careful filing on the counterweight stops. ( that was my Aries 13.0-1 compression pistons. ) now those were over bored to 3.72 please note; that is not California complying. That is 4 degree ATDC static and 18Degrees total.
Regarding gasket thickness all I have are new gaskets. I don’t keep old trash. So I have nothing that is already compressed. I do know that you won’t have enough gasket to try to use HE pistons on a Flathead. Do the math. The Flathead has 0 cc combustion chamber and the valves when seated stick proud of the head. How much depends on what was done at the last valve job.
The HE head does have a combustion chamber so you can do the math and calculate what putting a 6.0 head on a 5.3. Will yield.
Documentation is based on Haynes manual page 21. About the middle of the page under Piston Rings
 
  #176  
Old 05-01-2020, 05:03 PM
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I'm using he heads. Just gonna deal with the poor flow. At this point all my goal is to have a turbo v12 Jag and daily it.
 
  #177  
Old 05-01-2020, 05:09 PM
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The Total seal S1444 is for 5.3L only!
CR8254 is for 6.0L. There is gap less.
 
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  #178  
Old 05-01-2020, 05:10 PM
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Thanks for pointing that out!
 
  #179  
Old 05-01-2020, 05:17 PM
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Originally Posted by ronbros
you should buy Total Seal rings , they are much better than factory Jag , they are made for forced induction engines!
i have used them in many engines! MG probably never even held one in his hands!
ron
I tried Total seal back in the 80’s on Chevy’s I was building. What I liked about them is how good the numbers were in leak down tests. Not uncommon to show almost Zero percent leak down. With regular rings I has happy if I could get leakage under 5%
What I didn’t like is when the air filtration system failed and some track debris got in the Hilborn injectors. The rings couldn’t finish a 30 minute track session. Without pumping out enough oil to get the car black flagged. Regular rings would have held up at least long enough to finish the race. When I pulled that engine apart not only were the rings bad the cylinder walls didn’t clean up and needed new sleeves and new pistons.
You can fairly say that it was the fault of the air filtration system. But that was all we had room for. And when it had failed in the past a hone, new rings and the engine was back together.
I’ve built and raced enough cars to know that things seldom go according to plan. I’ll trade a few horsepower for a season of racing.
 
  #180  
Old 05-03-2020, 10:22 AM
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good thread on you tube, ( BANKS , 912 hp Duramax using stock engine ).
some interesting information engines!
 


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