Lets talk about cams

[StanTheMan]

http://garage.grumpysperformance.com/in ... -dcr.1070/

[Boyracer]

Kelford cams in New Zealand, bought some for the Goldie 2, about $830aus. delivered, impressed with the quality....I just got them because I wanted it to sound like a race car when I start it....it's at Mania now getting Adaptronic fitted, will be good to see how it goes.

[StanTheMan]

For a ghetto build. is it worth getting the Cams degreed? keeping in minds the cams are installed & engine is not coming out any time soon.

[a222133]

Recently built my b6 , so here is some specs which may be of some interest . Kelford 203-b cams [hyd] 264in 256ex 9mm [ yes I had to massage the lifter bores quite a bit to get clearence ] new KIA lifters Adj. gears , Eibach single springs 66lb , Head unshrouded blended by a professional , all ports matched all the way to itb stacks , head machined 20 thou. forged 10.6:1 pistons [ 1 mm over around 1640cc ] to give around 11.1:1 . Forged rods , ARP bolts on rods and head . Block decked around 15 thou to give final squelch of 27 thou with oem gasket [trying to control knock]. Billet oil pump gears + uprated relief spring . 12lb c/moly flywheel . JASMA headers into free flow cat then 2 1/4 " system . Silver top ITB with 75 mm stacks , 315 cc injectors K&N filter . Controlled by Adaptronic . This engine is just for fun street use ! so rpm is set at 7000 ,nice flat torque curve , pulls really well all the way through but is insane after 5000 did I mention the noise

[NitroDann]

Can you post sheets or slip?

[StanTheMan]

That's quite A BUILD
Vtech just hit.....ohhh wait....

Lifter bores at 9mm.....OK mine have already been done for previous cams in its life when a she had a lady driver on weekends only. Phew....
What is the consensus of a novice matching ports?

Mine are the kelford 203C

as far a interference with Lifter & pistons goes, Ive been a little worried. However theoretically speaking. The Mx5 Engines in stock form are non interference.
Which would mean that if the valve is at its highest lift.....about 8.9mm? and piston at TDC we should have at least 8.9mm clearance.

Currently on the 203 C at TDC the valves are at 2.3mm lift. Even If the head gets a shave of say 40 thou....1mm? There should still be around 5.5 mm clearance.
If hypothetically speaking I was to advance the intake by 4 degrees. Is there a way to calculate the lift at TDC? I remember Radians at School & Tafe.....blew my mind.But it was like 30 years ago.

Yes I get it. I would still need to check physically & make sure there is no interference. But I doubt the extra lift of 4 deg would be massive. But It wouldn't be 5.5mm extra? I do understand that trhe cams need to be degreed so I have a base to work from. Ive just dropped the cams in. While the cams or com sprockets may or may not be out slightly. the consensus seems to be it can be anywhere +/- a degree or 2 because of in accurateness on either the cam gears or the cam grind.

[StanTheMan]

Can you post sheets or slip?

you can find them here http://www.camshaftshop.com/products.ph ... =873#specs
I'm sure a222133 will not mind me posting it on his behalf

[StanTheMan]

Is anyone happy to share.

At what stage do the ports become an air flow restriction ? This is perhaps irrelevant to FI.
in a thread from a little while back the subject is a NB8A head. Talk goes that in a stock situation after reaching 9mm lift. With the amount of air coming through & stock size valves. The ports become the next barrier.

Can anyone share this info on an B6 head?

[93_Clubman]

What is the consensus of a novice matching ports?

You probably saw the following, but recall Phil mentioning this recently:

Also, casting and machining quality on B6 and early BP heads was pretty variable. On my original head about 35% of the available inlet port area was lost to mismatches in inlet manifold flange and gasket positioning. I see nothing wrong with matching ports to manifolds and removing casting dags and machining faults inside the ports... Depending on the original quality you can pick up quite a few hp there.

viewtopic.php?f=57&t=39676&p=884430&hilit=port#p884430

[StanTheMan]

Right....
I didn't see that.
since Patchy is far from standard.....If I match the seal & port.....should see some decent benefits.

[madjak]

There are mostly 3 factors that affect the airflow going into a head. My guess is it goes something like this:

Valve diameter : factor x 4 (most important)
Valve seat: factor x 3 (very important)
Cam duration: factor x 2 (next importance)
Cam lift: factor x 1 (least important)

The most important area for an engine is the airflow over the valve and seat up to half valve lift, that's the area where over 2/3rds of the air will get into the cylinder. The air speed is the highest as the valve cracks open so flow turbulence is more critical. So it all comes down getting the valve shape, seat (3-angle cut etc) right. .. everyone flow benches their heads at max valve lift, but the valves are open at that point for the least amount of time. High lift cams will help, but not as much as increasing the diameter of the valve or getting the valve seat right and increasing the time the valve is open.

My guess is that you should match the % increase in runner size to the % increase in valve diameter, plus a bit for longer duration cams, plus a bit less for high lift. That's not very scientific but it's the general gist.

There is a second benefit to porting, in that you can also reduce the radius of any internal curves which also helps overall flow.

I suggest watching this video... it's very old but very good at explaining valve flow. Skip to around the 30 minute mark.

[manga_blue]

The most important area for an engine is the airflow over the valve and seat up to half valve lift, that's the area where over 2/3rds of the air will get into the cylinder. The air speed is the highest as the valve cracks open so flow turbulence is more critical. So it all comes down getting the valve shape, seat (3-angle cut etc) right. .. everyone flow benches their heads at max valve lift, but the valves are open at that point for the least amount of time. High lift cams will help, but not as much as increasing the diameter of the valve or getting the valve seat right and increasing the time the valve is open.

Don't forget about the benefits of valve unshrouding when you're thinking about flow at partial lift. On a B6/BP head there is really very little space between a partially open valve and the side of the combustion chamber. Unshrouding close to the valve seat can be effective at improving flow at partial lift because it allows flow around almost 50% of the valve circumference where it barely happened before. Similarly I have some doubts about benefits of increasing valve diameter because it brings them back closer to the chamber wall again.

Right....
I didn't see that.
since Patchy is far from standard.....If I match the seal & port.....should see some decent benefits.

It'll only show benefits if your port alignment is already pretty bad. On my original head the manifold gasket covered about 5mm of the top and rear of each port while the manifold itself covered about 5mm of the front and bottom of each port, given an effective 10mm reduction in port height and breadth at the manifold interface. My stock NA8 initially dynoed at 48rwkw, partly due to this and partly due to exhaust restrictions. I imagine few other heads would have been as bad as mine ex factory.

[datfreak]

Most of you here have probably read about Quinns naturally aspirated 172hp non vvt bp. He later got a little more out of it with more CR and basic porting but the big gains had already been done.

What makes his car special is that this was with a standard non ported head / standard pistons and block. And no e85
The 'racing' Maruha cams are 10mm 264 duration -anyone have a guess what the .50 duration would be, somewhere between 220-230?

I think cams potentially can make the biggest power gain(while staying n/a). Followed with intake manifold(either honda or itb) and boosting CR are the best bang for buck for our engines. Porting/big valves are for those chasing the last few hp - although basic port and gasket matching is par.

Quinns car http://forum.miata.net/vb/showthread.php?t=496172

[NitroDann]

What does his dyno sheet trap?

[datfreak]

Is trap the rpm at max power?
Eyeballing the graphs it looks to plateau about 7200-7600. Not crazy high