The B20VTEC discussion thread

[ewendc2r]

Lol might have saw something about that .. Who knows.. But no disputing he knows his shit..

it seems what is being suggested is to build something mediocre rather than great? Benson I thought you had a fairly opened up head? I'm trying to figure out where you guys think I am going wrong? Hmmmm.. Seems stock heads just don't do the b20 capacity justice......

[tinkerbell]

you need a proper plan.

you still seem to be feeling around for stuff. but you need to set a specific goal and work from there...

[Chr1s]

I don't think were getting that technical, there is alot of things we overlook when picking combinations.

I'm seriously always learning, I don't think there is ever a time where I put together a combo and leave it at that, i'm always adjusting it as I go along. But this is for the big builds, the small street stuff is not too bad. I think it's part of our nature as Australians, not that we're Australian by blood, alot of us are from all over the world but our attitude in this country we don't like to just copy and follow others. I know for fact that Australian engineers are held up highly in the world for our work ethic. Maybe this is why we always like to get to the nitty gritty of the engine?

I still want to keep it technical, so lets kick off another topic.

What is your experiance with setting the camshafts? Do you always degree them and leave them and play slightly on the dyno? Do you have a specific ballpark setup that you choose and adjust it again on the dyno?

[tinkerbell]

What is your experiance with setting the camshafts? Do you always degree them and leave them and play slightly on the dyno? Do you have a specific ballpark setup that you choose and adjust it again on the dyno?

camshafts should be degreed in and then P2V and V2V clearance checked before final head installation... the cams should be re-degreed once the final installation is complete.

any 'playing' on the dyno should be minimal, however, the expected 'playing' zone should also be included in the P2V and V2V clearance checking noted above.

any high-lift/long-duration camshaft must have clearances checked - regardless of anything that may have been 'read' regarding other peoples setups...

[tinkerbell]

P2V = piston to valve
V2V = valve to valve
P2H = piston to head

[ewendc2r]

Ok I thought I had planned my build? Maybe I hadn't informed you ..

As there are discrepancies with US power readings I have generally gone on shape of dyno curve & quarter mile times where relevant ... Anyhow I've tried to keep the info as usable / comparable as possible.

As far as the bottom end goes, ITR Crank - Carillo Pro-A Rods - Endyn Pistons (12-13:1). Wasn't sure about bearings yet, some swear by the OEM ones which retain oil very well due to their design .. (not going into it).. Not sure if ACL are similar. Machining is obviously important and the relevant measurements will be made and nothing will be rushed -- I just need a good machinist and someone who has lots of experience sleeving without problems. The central recommendation seems to be build a bored B18c so I retain the factory VTEC oil passages and reduce risk of leakages etc.. Also I then retain the stock Girdle and oil jets (not necessary for forged, but I'll take them all the same -- unless they can radically effect oil pressure??)

Head - This is the powerhouse. And why I don't understand my comments above mean I'm building a dud ... Endyn Head with full valvetrain (nitrate coated ss valves 1mm oversize intake only, double springs, tit retainers etc .. the usual) and full endyn polish / port. Combustion chambers reshaped and cnc'd to 84.5mm, cold welded blah blah blah .. The full gig. Now, with the compression of the bottom end, I've been advised that I should use a pretty big cam, but not too crazy (i.e. not S2P3 which are maassiive but S2P1 are likely a very good compromise)..

The b16 head & b18 head are designed for a certain flow rate of exhaust / intake mixture or gases.. The reading I've done suggests that for a 2L they really benefit from being opened up and further advances since the head was designed 15 years ago or so including changing the combustion chamber and deshrouding valves etc etc ...

With stock head it seems max output is around the 200whp (US), with cams and stock ports its around 220whp. Now for the interesting bit .. With stock head and S2P2 cams, around 210-220whp but as soon as the chambers are opened up and ports, well, ported, increases are seen all over the sheet (ie avg horsepower increase, not just peak)..

I always thought that max torque is where max VE is reached in an engine.. Obviously, the cams play a large part in determining where VEmax is.. I'm not looking to build a 10,000rpm 2L engine (although, I would think it could do on occasion without dramas) but something that will develop power to around 8800rpm.. Happy with a limiter around 9200rpm -- Compromise on ring wear and peak power levels..

From the dyno's I've seen, the S2P1 cam seems to provide a very usable power curve all the way to 8500rpm.. And then hold for a couple of hundred rpm in some cases (not sure how?) before trailing away slowly.. Of course --- These ALL have the RIGHT supporting boltons ie tri y and velocity stack style intakes usually with single throttle body (68mm to 70mm) .. I am making do with what I have FOR THE TIME BEING i.e. Until I establish a base level to improve from.

I don't see where I am shortcutting anything and/or what I am doing wrong with the head choice? Nor do I see where I am going wrong with the short block ? I am in essence, copying what a lot of high output engines in the states are using (and I have avoided Drag or RACE ONLY setups who go even further again)...

[ewendc2r]

Regards timing -- For some of the bigger cams (again, i.e. S2P2) they seem to use around 4-5 degrees of separation .. ie. +1 +5 .. But is this from 'zero' or from where the cams where originally degreed in?

If you have a certain amount of adjustability is the only reason to adjust them initially to create a 'zero' point that is closer to optimal than otherwise?

This is one area I haven't read a great deal into.. But the bloke with the head said there will be no v2v interference with S2P1 at 0/0 setting but will definitely benefit by tuning on dyno and adjusting.

[tinkerbell]

hmmm, that is not really a "plan" though is it?

of note, 1mm oversize valves and Skunk 2 Pro cams? the spec sheet states:

WARNING!!
• It is the responsibility of the engine builder or end user to check all clearances when using high lift camshafts.
• Pro Series Stage I camshafts are not emissions legal.
• DO NOT use oversized valves.
• DO NOT increase overlap over specifications below.

and that is just for the Pro1's, the pro2's and Pro3's carry the same warning...

http://www.skunk2.com/installation/305-05-5140.pdf

i.e. a "plan" will include aims, budgets, specifications etc... not half just a list of parts...

[ewendc2r]

....

And there is also a huge amount of feedback saying that although Skunk2 says not to use them, they still work with the right setup.. If i'm not absolutely sure about what I am doing you can bet your bottom dollar I'll get someone to do it for me. But they do it, and it works.. They're experience indicates problems with anything over 1.5mm (or say, 1mm intake, .5mm exhaust .. too much) .. As before, not saying there is 'much' clearance... but it is there.

Look -- Aside from my budget the above should be able to indicate if the build is a dud or not surely? i.e If I gave those parts to someone like Adrian to assemble, would it still be a dud? Therefore are you saying the extra 20kw comes down to assembly? And if so, if I'm not in a mad rush to get it in the car, surely I have the resources to make sure any machining is exactly how I need it and can talk to the right people in the industry.. Unless its some kind of black magic?

I've built 2 engines before, given not performance but they are still running today years after I built them (maybe 6 years?) .. Its not like a pick up a socket and ask 'whats this?'

[tinkerbell]

OK, so you need to ask yourself 'why' you need oversize valves.

for example, there are loads of setups running stock valves, what is it about your goal/aims that mean you need to go bigger, and will using them will compromise your other goals/aims, e.g. streetability & reliability

then if you do fully consider that you need them, then you need to plan out what other components are required to create the 'right' combination.

[tinkerbell]

I've built 2 engines before, given not performance but they are still running today years after I built them (maybe 6 years?) .. Its not like a pick up a socket and ask 'whats this?'

there is a vast difference between "putting together an engine" to "blueprinting an engine" (which is what you will be doing with what you are proposing...)

e.g. what piston to wall clearance did you use? what were your bearing clearances? what ring gaps did you use? etc etc

[ewendc2r]

I didn't .. Just went oversize and away we went.. But I have the right equipment to make all the measurements... Except plastigauge..

Reason for oversized intake is to compliment intake port flow on higher displacement engines with big cams that need efficient quick intake charge?? Taken, the head is cheaaap.. And was built on a 92mm stroke short engine with slightly bigger capacity.. Which may need slightly larger intake flow capability.. Have to be better than a non cnced b16 head in any case ..