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Discussion in 'SN95 4.6L Mustang Tech' started by GDawg, Dec 23, 2006.
Matt, The picture is almost 40 years old and in very bad condition it is my avatar.
Bill, Can you tell me which of the 4 timing events
116.5 111.5 Intake Centerline
1) intake opening - 26 BTDC 31 BTDC
2) intake closing - 79 ABDC 74 ABDC
3) exhaust opening - 88.5 BBDC 93.5 BBDC
4) exhaust close - 35.5 - ATDC 31.5 ATDC
causes this? Overlap is 61.5 degrees and will not change. Hint check what happened to the dynamic compression ratio if your sim shows it.
Duh, it didn't even occur to me that your avatar was the picture you were talking about....too much race gas fumes I guess, LOL.
I don't see any pictures in your garage or under your profile. Can you post some here in this thread for us.
Just a second ago you were saying how you would take torque any day over HP....now all the sudden you have jumped ship and switched to the horsepower club. And now you have included yourself in the "HP is what we are all here for" group?? Which is it Bill?
Spell check is a man's best friend.
I'm sorry but I'm going to have to call
Your not very clear here...so just so me and everyone else understands this. Your giving 2 intake centerlines. Same cam but say the 111.5 CL cam is installed 5*s advanced and the other is straight (0*s) up right? Your basically wanting to know which of 1-4 represents the correct change in the valve timing sequences?
Bill may be able to answer this, but jeeze...make what you want more clear next time.
If 2 people are discussing things and arent making much sence, how is that benefiting this forum? We are all here to learn, just make clear what your wanting so atleast some of us can see whats going on lol. My .02.
Don't be sorry. I was the reason that Kevin had to be there at the PR event I managed for that Jeg's Engine Masters Comp. We all saw the good 'ole Elephant put up the big numbers.... there is a big digital sign for everybody to see right over the Lexan window in front of the engine dyno operators. It's no secret that the 425 HP factory rating of the 426ci Hemi was enormously underrated.
It was not surprsing at all to those of us who have been around long enough to have been directly involved with the Hemi. I will never ever tell my age on here, but let me just give you a hint.....when I first started racing professionally we were racing a 1949 Pro Street Anglia.
Sure he is clear. Stan was just quoting the 116.5 LSA (lobe separation angle) that billfisher typed. The 111.5 is the ICL or intake center line. That refers to where the camshaft has been installed in the engine in relation to the crankshaft.
I know exactly what Stan is getting at, and we will see if Mr. Bill gets it right.
^Me too LOL.
And by clear, i mean so the adverage person knows what he is wanting Bill to answer.
He just says "Bill, Can you tell me which of the 4 timing events causes this?" and posts up some specs on at what crank rotation* the valves are opening at. My question is.....CAUSES WHAT? Whats "this" ?
Maybe the engine compression on a certain cylinder will be lower because the intake or exhaust valve are closing after the compression stroke is started and he wants Bill to say which of those 1-4 is causing it....or maybe that sequence is all wrong and both the exhaust and intake valves will open at the same time and the engine wont run....or maybe.... See what I mean?
Guess we will all find out shortly lol...but I doubt anyone could just look at those specs and say "OHHH heres your problem" ...if thats what hes even wanting.
I know this is a bit above my head but it makes no sence to me.....and Im sure that 99% of the rest of the people reading this dont have a clue as to what hes talking about either.
The intake valve will always close ABDC. Without going into great detail, that's dynamic compression. What Stan has posted is referred to as VE timing (valve event timing). Bill posted that he ran a particular camshaft on a software simulator and the software showed that the cam made more power under the curve with the cam installed "straight" up as opposed to being degreed with a 5° advance. The he said something else that made no sense. billfisher: "i will personally take the average torque and shift it early to gain up until the two hp curves swap. the small rpm advantage and peak hp advantage is nearly useless."
This should be interesting to say the least.
When a cam is made the lobe separation angle is fixed. This is the relationship between the intake centerline and the exhaust centerline. As the cam is advanced or retarded the intake and exhaust centerlines change together. On the 116.5 LSA cam straight up the intake and exhaust CL is 116.5. If advanced 5 degrees the intake CL is 111.5 and the exhaust is 121.5 and the LSA is still 116.5. This one reason to go to DOHC's so all of these can be changed separately.
^ right LSA is grount into the cam and can not be changed....I knew that, but you just didnt list what the 116.5 and 111.5 was in your original post. Now I know what you talking about....thanks all .
And laser my assumption was based on him giving a jacked up cam profile (not a correctly designed cam whos lobes are ground at the correct sequence to allow combustion) IE a trick question.
So thats why I gave that example...I know thats not possable on a correctly ground cam as the lobes are seperated (LSA) by X *s depending on cam profile. Although if the cam is degered so wrong the engine wont run....but it will never have both intake and exhaust valves opening at the same time, unless like said, if it was ground improperly. Thanks again for saying which # was what
I am still not quite sure you're grasping this. The intake and exhaust valves will always be open at the same time during overlap. It doesn't matter how you degree the cam, during overlap the intake valve will always open before the exhaust valve closes. This is where you get the scavenging effect to help draw a/f into the cylinder.
And combusting will occur no matter how bad the cam is degree'd. As long as you have fuel and spark, you have combustion. The reason for getting the VE timing correct is to optimize cylinder filling, dynamic compression, and optimize the overlap scavenging. You can also pulse tune with the intake valve if you were to have DOHC like Stan mentioned.
Notice I said "opening"...as in the intake and exhaust valves openING at the same time. I wasnt saying they would never have valve overlap, just that they wouldnt start opening at the same time....unless the cam was ground wrong.
SO your saying that if I degree the cams @ 60*s advanced that it would still run? Ill say that there would be some serious PTV contact LOL..if it was a non interference engine I still dont see the car running or the engine gaining enough compression for cumbustion because the valves would be opening at the wrong times and allowing the compression to to escape via an open valve. Right?
My tune consisted of me cranking up the boost and pulling the timing to +5* and then flooring it repeatedly.
I Set out to destroy her, so dont be sorry
I honestly do not mean to sound like a smartass when I say this, but let me quote the defintion of "combustion" from the dictionary.
Combustion is not in any way dependant upon compression. When you throw a lit match into a cup full of gas, you are combusting that gas/fuel.
If you have ever worked on an older car that has a tradtional cam driven distributor and you stabbed the distributor 180° off, you would see how the spark plug will ignite (combust) the a/f that entered the cylinder without any compression.
I never said the engine would run no matter what, I said that combustion would occur no matter how the cam was degreed. Now of course, God forbid, someone was to degree a cam so far off that it made P to V contact, of course it wouldn't survive very long - but you would have a really cool paper weight!
LOL ok...I guess technically combustion WILL happen no matter where the cam is at because spark and fuel= fire but I guess I was using the wrong term.
I was meaning more or less the term "explosion" . Didnt expect anyone to get so technical on me But your right in what your saying...I was missunderstanding.
ok i'm jacked up on tequila but i will plug them in later.
it is common knowledge that cam phasing affects rpm torque band. that's all i was saying. the sim numbers i posted previously and you can surely look them up in a search. i am going to the dyno this spring and i am determined to work out the bugs with VCT control. i will do a number of runs with it and without it. you already seem to know the results but other don't.
MMFF did a test of 4.6 3v on the dyno and jumped a tooth on the stock to observe power. they noted a 40 lb-ft loss and a 20hp gain. with the cams .25 degrees from straight up. i am simply stating the same.
any sim shows the same thing. as far as calling me out on my sim . KMA and all of the other call outs you and your buddy sitting next to you are trying.
on the hemi thing. i think it is an honorable idea to top the venerable 426 with a motor. how am i switching when i look forward to topping it's rwTQ and rwHP. with a 330?
i will plug those nuimbers into the sim. later. i care little for this with 3 shots of tequila..
ok the dynamic is 3.75 on one. so what. and 4.14 on the other. those are not my specs. not even close.
i fail to understand what you have demonstrated. who is this aimed at? if me, then here we go again.
WOW! So you didnt add any fuel? And you set total timing to 5*s? Guess the turbo isnt fading out Your tune was probably so lean that it was killing power....and then the 5* timing was also killing power. 500RWHP wasnt too bad
Im honestly suprised that it lasted that long! What was the A/F at?