20v and aftermarket cams...

[Sam_Q]

I have seen the dyno run of a before and after of going from stock cams and then to the Kelford 194C with VVT enabled and unless something was really wrong the result was in my personal opinion was dismal. It had only a 6% gain in the top end and a decent drop all up the way up to 5400 revs. A cam with that lift and duration should be doing a lot more for the engine than that. The workshop that was playing with it even tried using an offset pin to move the static position of the pulley but to only a limited gain.

It seems like the only proven VVT compatible cam profile is the rather sedate Tomei "Poncam". Regardless of how mild the specifications are they seem to do really well with nice gains right across the rev range. Tighe also do something that's VVT proven but I have yet to find out which profile and specs they cam offer.

Just1n_mc: do you know which cam grind do you have? The 272A? If so I have experienced it first hand with VVT enabled but that was on a Silvertop which has much greater valve to piston clearance.

fixeruperer: I would also very much like to know how this is possible because short of something being welded to the outside I can't see how it could be.

[Just1n_mc]

indeed. for a track n/a 20v, you should really never be below 6000rpm (a C160 will help your cause here if you dont already have one). And if you don't give a shit about what's happening under 6k, then I say you get yourself some fat cams and some adjustable cam gears and forget about vvt....

I'm running a LSD C56 instead of a C160 from a strength point of view. It have a TRD 4.733 final drive to go into it so it should help get the most out of the engine.

I think I'll set it up without VVT unless fixeruperer can elaborate on his pinning the VVT solenoid.

[101gze]

I'm not fully understanding exactly what you are saying....??? that an Atlantic engine doesn't(didn't in 2008) twist to 13,000? They use too, but do to development, they don't need to spin that high anymore... they twist to about 10k-11k. OR that they don't make 240hp, some do... some make more...

this one makes more....

Makes more what? wheres the power figure? If your not sure what Iam trying to say, Iam saying that no 4age is capable of "twisting" to 13000rpm in 2008 nor any other year regardless of development. Do you understand that n-o-w?
Are you saying that the engine in that video you posted is "twisting to 11000 RPM?? or 13000rpm? and making more than 240hp? is that your internet opinion? are you basing it on the sound of the rev? Loynings have offered no data to back up your claim, I dont think its more that 9500 at most, but as I say, you must have a dyno plot with rpm and and output since you live at Loynings.

Just show us the data, its easy

13000 RPM - output
11000 RPM - output

Do you know what the formula atlantic engines were limited to by regulation?

Can you explain to us just what ecu is used to "twist" these 4ages to 11000 or 13000 or whatever RPM your in the mood for?


No, you dont because just like unicorns it never happened and to be technical as to why, ITS NOTHING TO DO WITH CAMS AND PORT WORK! OK?!?!

And, just to stay on topic you asked for evidence as to HOW THE 20V can handle more DURATION than the 16v Ohhh how can it be sooo ohhh... Hows this:http://www.hotrod.com/how-to/engine/...mshaft-basics/

And to further simplify:
Assuming we are choosing a cam for a streetable engine, how much overlap can we use before it becomes a problem? The answer here is that it depends on the valve sizes in relation to the cylinder displacement. If the heads have small valves in relation to cylinder cubes, then the amount of overlap we can use is significantly more than the same cylinder with much larger valves. For instance, a 500-inch big-block Chevy can tolerate not only more overlap, but a much bigger cam because the cylinder heads are so under-valved for the displacement. A 350 small-block with a set of decent heads has a lot more valve-per-cube, so it does not need so much overlap to get the job done.

So...if we are talking the same displacement as pertaining to the 4age the engine with SMALLER valves will deal with and BENEFIT from increased duration more so than the other.'

Is that the answer you wanted? probably not.

[Just1n_mc]

Just1n_mc: do you know which cam grind do you have? The 272A? If so I have experienced it first hand with VVT enabled but that was on a Silvertop which has much greater valve to piston clearance.

Sam I've got Clive 396A's. I'm going to run them in a Silvertop.

[fixeruperer]

i dont know what it looked like on the inside, but there was two studs with nuts on the outside of the pulley 180 apart. i asked the guy that brought it in (wtf is going on here ?) and he said to limit its advance/retard as its running massive cams.

im guessing that the studs either may have ran in a groove that was machined in the inner vvt and the studs limited its travel
or
the studs were to limit the travel of the vvt inner gear as like a stop so the oil pressure pushing the inner gear (which changes the timing ) couldnt proceed in moving the inner gear.

but i never had one of these vvts apart, i just seen a bunch of euro vvt shit.

[oldeskewltoy]

https://www.google.com/webhp?sourcei...antic+4age+rpm - numerous 10k, 11k, 12k Atlantics

if it would make you feel better... I was incorrect back in 2008 when I said Atlantics were capable of 14,000 rpm....


Problem is context... the chevy engines you refer to have only a single valve(one intake, one exhaust)... what you aren't accounting for is 1) 3 valves equal MORE, not less even though the individual valves are smaller, the total is greater. 2) the larger the lift, the more disturbance the 3rd intake valve suffers from do to too much influence of the other 2 valves that as lifts increase the total air charge actually begins to fail... I've got flowbench #s on a silvertop intake and although the low lifts are significantly better then a 16V, as lifts increase the flow begins to fall back toward 16V levels.

common ecu is Pectel

If the 20V(5 valves per chamber) was better... why is it no longer available from any manufacturer that ever made one???

If you'd like to continue this - how about a different/new thread so we don't fill this one with extraneous information

[trdee]

Going a bit off topic now, but I thought the 20vs weren't used any more for cost/complexity reasons IE a 16v head gets close enough for a lot less money (from an OEM perspective)

[Sam_Q]

I have seen the inside of a 20V VVT pulley but it took a grinder to open it up, I can't see how it would be possible to open one up and put it back together to a functioning state ever again, but I would be happy to be proven wrong.

As for the 4 valves versus 5 it's simple - having 5V has more downsides than up, hence why motorbikes and any dedicated race engine is always 4V unless there are special reasons at play.

[fixeruperer]

well it wouldnt be possible with that attitude !!!! haha.
but yeh, it was done.

[101gze]

https://www.google.com/webhp?sourcei...antic+4age+rpm - numerous 10k, 11k, 12k Atlantics

if it would make you feel better... I was incorrect back in 2008 when I said Atlantics were capable of 14,000 rpm....


Problem is context... the chevy engines you refer to have only a single valve(one intake, one exhaust)... what you aren't accounting for is 1) 3 valves equal MORE, not less even though the individual valves are smaller, the total is greater. 2) the larger the lift, the more disturbance the 3rd intake valve suffers from do to too much influence of the other 2 valves that as lifts increase the total air charge actually begins to fail... I've got flowbench #s on a silvertop intake and although the low lifts are significantly better then a 16V, as lifts increase the flow begins to fall back toward 16V levels.

common ecu is Pectel

If the 20V(5 valves per chamber) was better... why is it no longer available from any manufacturer that ever made one???

If you'd like to continue this - how about a different/new thread so we don't fill this one with extraneous information

This is not about making me feel better.

You said they were capable of 13000rpm, not 14000 but you clearly think that its all just phantazmagorical herdy gerdy so, even though you cant read you own garbage, I wont hold it against you. The post you offered shows NOTHING MORE THAN PHANTASY BULLSHIT

Nothing more than a pack of toolbags talking utter crap about what they would like to build: ooohhhh mmmm geee I would lerve to bilz me a 11000 rpm monsta GE... can u bwuvas tell me howz I canz??? can ya? huh??? can ya??

You asked for evidence as to how the 20v can deal with duration over 16. I gave it to you as simple as it gets and you reply with:
1) 3 valves equal MORE, not less even though the individual valves are smaller, the total is greater.

That is EXACTLY THE ARTICLES POINT A larger valve area with LESS VALVE HEAD SIZE = better use of duration. The article explains that clearly.

2) the larger the lift, the more disturbance the 3rd intake valve suffers from do to too much influence of the other 2 valves that as lifts increase the total air charge actually begins to fail...

Really? See, now here your regurgitating unfounded crap from...gee..the year 2000?? yeah? I think thats when I first read that little ditty.
Firstly, did you actually write this yourself? or cutnpaste? because I dont know what the 3rd intake valve is...and I'm pretty sure the 3rd intake valve would not appreciate the discrimination.

Your one of the muppets that thinks that the induction of a charge is some perfectly organised, presented friendly little get together of an oxygen molecule and a precious mole of fuel...yeah? and to make the matrimony perfect, we have 1 valve on the left and one on the right.
And they work with each other to make a lovely swirl and invite everyone into the cylinder to be as one... oh how lovely

WRONG!!!


The induction and combustion of an intake charge is an ugly cacophony. If you watch that video, there is no evidence of the precious chorus you like to delude to.
Its an nasty place to be, the forces are such that they can melt the toughest hardest nastiest most clever metals in an instant.
Clearly by viewing this brilliant video, we can see that all you want in an engine is a set of valves that open and allow an avalanche of air to be inducted. I give you the 20V! The whole inlet side of the chamber can open up and flow an avalanche.

"I've got flowbench #s on a silvertop intake and although the low lifts are significantly better then a 16V, as lifts increase the flow begins to fall back toward 16V levels".

Show them. Was the head ported? was it flowed on the same machine as the 16V on the same day? If not, the #'s are pointless, but hell..humor me, show it anyway.

"If the 20V(5 valves per chamber) was better... why is it no longer available from any manufacturer that ever made one???"

Once again, as you always do, you make this a 20v vs 16v debate. Its a really simple answer as to why the OEM's dropped the 5 valve.
Emissions. Thats it. Government mandate. But whyyyy??? well, the head of Yamahas development team on the R1 said in Fast Bike magazine that the shape of the 5 valve chamber is a dirty burner. that is, the requirement of the "centre" intake valve (3rd valve in your speak?) extended the flame propogation to the point that it created too much NOx to meet Euro 5 emissions laws, he further stated that whilst Yamaha had a great deal of development gains to come with the 5 valve, Europe was their largest market and it was dictated to them, by the boffins, to clean up there act and the 16v R1 was born.
That along with the extra cost and the fact that the oem performance world was beginning to be frowned upon, brought about the concepts demise.