building a 6.8 ltr v12
#61
10-15-2013, 11:35 AM
Senior Member
#63
10-15-2013, 01:08 PM
Calvin:
Yeah, now that you say that, I agree- Group A valve sizes were fixed at OEM values.
The pix I posted were represented to me as listed. Although I have to say, I always suspected that the Group A and Group C intake port pix might have been reversed...The 'D' shaped inlet seemed to me something more advanced that simply boring the inlet to a larger diameter.
So, it may well be that the valves in head pix is erroneously labeled (as I received it, that is).
Yeah, now that you say that, I agree- Group A valve sizes were fixed at OEM values.
The pix I posted were represented to me as listed. Although I have to say, I always suspected that the Group A and Group C intake port pix might have been reversed...The 'D' shaped inlet seemed to me something more advanced that simply boring the inlet to a larger diameter.
So, it may well be that the valves in head pix is erroneously labeled (as I received it, that is).
#64
10-15-2013, 02:02 PM
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#65
10-15-2013, 03:57 PM
#67
10-16-2013, 08:50 PM
#68
10-16-2013, 09:50 PM
#69
10-18-2013, 06:30 PM
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a JAG R&D drawings from around 1971-1975, piston on left is original shape very close to race piston,tight squish .050, piston on right is the standard 5.3 shape, not much squish.
as bore /stroke increased you would need a lower center recess to keep comp/ratio acceptable, and the text talks about it being off set to favor spark plug!
port shapes are about all that they could do,for a single cam head.
exhaust is really tight turn,like 90*, so a D shape would be logical,and raised a little in your pic.
now a D shape inlet port, thats different, gotta be gp C after much flow bench work. i'd like to see the manifold that mates up to it, and it sure dont look stock (big port).
and last but not least old TW wouldnt cheat just a little (WOULD HE ?), that racing!
opps, or Allen!
gp44 1st use use chevy rods narrowed 1977. eventually went CARRILLO forged, for there later engines.
as bore /stroke increased you would need a lower center recess to keep comp/ratio acceptable, and the text talks about it being off set to favor spark plug!
port shapes are about all that they could do,for a single cam head.
exhaust is really tight turn,like 90*, so a D shape would be logical,and raised a little in your pic.
now a D shape inlet port, thats different, gotta be gp C after much flow bench work. i'd like to see the manifold that mates up to it, and it sure dont look stock (big port).
and last but not least old TW wouldnt cheat just a little (WOULD HE ?), that racing!
opps, or Allen!
gp44 1st use use chevy rods narrowed 1977. eventually went CARRILLO forged, for there later engines.
#70
10-18-2013, 09:58 PM
ive been building flat head race engines(racing lawn mowers USLMRA stock prepared) and the issue is flow, flow is go im seeing a pattern here on the exhaust holding this engine back kinda makes sense why it runs so hott i would definitely go for a big exhaust valve with flowbench work and find you vE i cant pull the from my brain now but ill post it later.also theres a bit of math involved in the manifolds that would help greatly im tempted too bring up fire slotting?!? I must run some tests my flowbench is not built yet so im dead in the water on that end.
#71
10-19-2013, 11:00 AM
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88 thats why i thermal coated my exhaust ports back in 1994, just to keep the heat from reaching the coolant jacket, also the top of comb. chamber, valves, piston tops.
its all about controlling heat losses in the chamber,we try to use as much of the available heat expansion to push the piston,not waste it in useless areas, plus more heat going out the exhaust helps scavenging of same!
what i'm seeing here is building a 45yr old engine to 45yr old specs.
what is new and different, they did not have engine thermal coatings in 1984, or did not have Extrude honing, as i have used, BUT my engine will never make 500hp either!
i'm guessing that,like said by Allen Scott, by the time you get to 500+hp with a jag V12 you lose most of its streetable quality, rough running when going slow , not much torque at low speeds, slip the clutch just to get moving in traffic,etc. forget fuel economy or quietness.
something like you would not use an allout race lawn mower for cutting everyday grass! LOL.
its all about controlling heat losses in the chamber,we try to use as much of the available heat expansion to push the piston,not waste it in useless areas, plus more heat going out the exhaust helps scavenging of same!
what i'm seeing here is building a 45yr old engine to 45yr old specs.
what is new and different, they did not have engine thermal coatings in 1984, or did not have Extrude honing, as i have used, BUT my engine will never make 500hp either!
i'm guessing that,like said by Allen Scott, by the time you get to 500+hp with a jag V12 you lose most of its streetable quality, rough running when going slow , not much torque at low speeds, slip the clutch just to get moving in traffic,etc. forget fuel economy or quietness.
something like you would not use an allout race lawn mower for cutting everyday grass! LOL.
#72
10-19-2013, 10:01 PM
#74
10-24-2013, 02:08 PM
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i was looking at some old R&D from Jaguar,when they were doing there 1st V12s.
they did use a 2.1 rod journal diameter, but found it could cause crank flex or whip, and felt that possible main bearing life may be effected, so they went up to the,larger, now standard size.
original engine design was for a race engine, so if mains suffered wear, it would be OK for race,because they would rebuild the engine more often.
you asked for Questions cal; what con rods did you end up with?
the 229 rod bearing is that a 6 cyl chevy,inline or V6?
did you cross drill the crank journals, for more oil flow?
were any of the cylinder block oil passages modified for more oil flow?
did you chamfer the oil hole leading edges for easier flow?
did you rebalance any of the rotating components?
what ring package is being used, widths of them?
was any friction reducing compounds used on bearings, beside assembly lubes?
what brand of bearing was used make and type?
what are the final bearing clearences ,mains and rods?
do the rods use any special hi-tensil bolts or nuts?
this could go on forever, or just maybe 1000 questions, on race engine building!
you had someone else do the actual engine build,am i correct here?
that would make it difficult to answer some of the questions,
i do understand tho,!
they did use a 2.1 rod journal diameter, but found it could cause crank flex or whip, and felt that possible main bearing life may be effected, so they went up to the,larger, now standard size.
original engine design was for a race engine, so if mains suffered wear, it would be OK for race,because they would rebuild the engine more often.
you asked for Questions cal; what con rods did you end up with?
the 229 rod bearing is that a 6 cyl chevy,inline or V6?
did you cross drill the crank journals, for more oil flow?
were any of the cylinder block oil passages modified for more oil flow?
did you chamfer the oil hole leading edges for easier flow?
did you rebalance any of the rotating components?
what ring package is being used, widths of them?
was any friction reducing compounds used on bearings, beside assembly lubes?
what brand of bearing was used make and type?
what are the final bearing clearences ,mains and rods?
do the rods use any special hi-tensil bolts or nuts?
this could go on forever, or just maybe 1000 questions, on race engine building!
you had someone else do the actual engine build,am i correct here?
that would make it difficult to answer some of the questions,
i do understand tho,!
#75
10-24-2013, 08:56 PM
the 229 bearings are from an inline 6 I believe. but I don't really remember. the rods are Manley sportsman rods. narrowed on the bottom end. the cylinder block was not modified, but the crank holes were chamfered,
the engine was assembled with assembly lube and, 30 weight oil, also the oil pump was packed with Vaseline, to insure suction into the engine on startup, because Vaseline desolves in oil. (oldschool trick I was taught a wile back)
the rotation assembly was balanced, individually with the crank first, then adding yhe flywheel and then balancer and pressure plate.
the rods used high tinsel arp hardware, and the clearences are .001 per inch of main. I think.
i am having someone assemble this block but I am there watching and he is teaching me as he does so. the bearings are king aluminum bearings, which are a street/track design.
these might be somewhat out of order, so just let me know if I didn't answer any.
the engine was assembled with assembly lube and, 30 weight oil, also the oil pump was packed with Vaseline, to insure suction into the engine on startup, because Vaseline desolves in oil. (oldschool trick I was taught a wile back)
the rotation assembly was balanced, individually with the crank first, then adding yhe flywheel and then balancer and pressure plate.
the rods used high tinsel arp hardware, and the clearences are .001 per inch of main. I think.
i am having someone assemble this block but I am there watching and he is teaching me as he does so. the bearings are king aluminum bearings, which are a street/track design.
these might be somewhat out of order, so just let me know if I didn't answer any.
#76
10-25-2013, 12:25 AM
looking forward too hearing this big cat purr 
i would highly recommend the head be worked on a flow bench the more you can get out ,the more that will go in haha im still searching for the formulas i have written down i will post those soon. ve is volumetric efficiency usually is 83% to 87% .
i would highly recommend the head be worked on a flow bench the more you can get out ,the more that will go in haha im still searching for the formulas i have written down i will post those soon. ve is volumetric efficiency usually is 83% to 87% .
#78
10-27-2013, 01:36 PM
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cam timing
Calvin:
Great details! I have seen Ross do 10:1 pistons for E-type V12s, so I guess this is why you went this route. Did they also supply the ring packs?
I would like to attach pix sent to me from another Jag Lovers lister, showing the Group A and Group C head details, and especially, the Group C piston. Anyone know how to do this (other than to insert a URL for the pix)?
I'd really like to know if this piston looks like yours? It appears to have valve reliefs cut into what looks to be the design you are using. I have no idea what the CR is, or the valve sizes (I suppose these could be estimated from the relief cutouts, though).
Do you know, does Beere do your piston design in other bore sizes?
HEY Mike;
mike, Scott is refering to,in USA speak, LSA(lobe separation angle),at peak lift,that number cant be changed once the cam has been ground. it does effect valve overlap period, depending on lobe profile, WOL loses low end torque but gains on top end(good for race engines that dont run on street),
bad part is in traffic or slow going ARGH! NO vacuum= no brakes,(guess how i know)! but have since remedied that problem.
what can be altered is the inlet center line of lobe,(sometimes refered to as advanced timing,or retarded timing of cam). he (Scott also refers to that number in his book!) with multi-cam engines,it can get tricky." " thx RON.
For others on this thread, regarding cam timings: in the TWR book, Scott indicates that cam timing as 100 degrees between lobes...I don't think I've ever seen cam timings referred to in this manner. Anyone know what this means in relation to the usual cam specs? Later in this book, where he talks about a custom 6.4L motor, he indicates that the cam timing is 110 degrees between lobes...
-M
Great details! I have seen Ross do 10:1 pistons for E-type V12s, so I guess this is why you went this route. Did they also supply the ring packs?
I would like to attach pix sent to me from another Jag Lovers lister, showing the Group A and Group C head details, and especially, the Group C piston. Anyone know how to do this (other than to insert a URL for the pix)?
I'd really like to know if this piston looks like yours? It appears to have valve reliefs cut into what looks to be the design you are using. I have no idea what the CR is, or the valve sizes (I suppose these could be estimated from the relief cutouts, though).
Do you know, does Beere do your piston design in other bore sizes?
HEY Mike;
mike, Scott is refering to,in USA speak, LSA(lobe separation angle),at peak lift,that number cant be changed once the cam has been ground. it does effect valve overlap period, depending on lobe profile, WOL loses low end torque but gains on top end(good for race engines that dont run on street),
bad part is in traffic or slow going ARGH! NO vacuum= no brakes,(guess how i know)! but have since remedied that problem.
what can be altered is the inlet center line of lobe,(sometimes refered to as advanced timing,or retarded timing of cam). he (Scott also refers to that number in his book!) with multi-cam engines,it can get tricky." " thx RON.
For others on this thread, regarding cam timings: in the TWR book, Scott indicates that cam timing as 100 degrees between lobes...I don't think I've ever seen cam timings referred to in this manner. Anyone know what this means in relation to the usual cam specs? Later in this book, where he talks about a custom 6.4L motor, he indicates that the cam timing is 110 degrees between lobes...
-M
Last edited by ronbros; 10-27-2013 at 03:55 PM.