Woah!! Can you make that a bit bigger please, Andy?... I can't make it out...
'tis rather large innitGood job I've got a 22 incher
and a A1 plotter but i think it'll hide all the engine
it's that size for any member surfing on their phoneOriginally Posted by Adam L
Lolit's that size for any member surfing on their phone
theyd b there a good hour b4 the page loaded lol
So those are the lairiest std cams? No wonder these engines struggle. You could run a diesel on timing like that. If these engines do have poor heads then they will need duration duration and some more duration.... 228degs is never going to do it. I reckon as a start you would need some thing with about 30degs more on an LCA (Lobe Centreline Angle please, we're not American!) of about 110 with 0.040"ish LATDC. Then you might start seeing some power and still shouldn't be sacrificing midrange.Found some data on the B28 Volvo camsI need to measure the std GTA lift but the timing is thus on the Z7U cam .
Inlet open 8 btdc
Inlet closes 40 abdc
Ex Open 40 bbdc
Ex closes 8 atdc
Volvo Cam ( it's odd fire but I think the lift will be similar to the B280E which is even )_ I think
Attachment 652
LCA is not the same as LSA... we're engineers
how can you tell how much LATDC the cam he quoted has?
infact how can you tell how much duration the cam he quoted has?
which has more duration, a standard GTT cam, or a Piper 270?
which has more duration, a Kent RT200, or a Piper 285?
How can you tell?
You're gonna say ' by measurement ' aint ya
LCA is about 170 on one and 10 on the other ?Somewhere in those figures I'm sure there's a clue
Cam A
Cam B
Lee,,,,
if Rennie and Honda can get 1000BHP + out of a 1500cc.......sure we can do something for you Lee.....LOL..
now, the stroked crank isnt near enough to sort what you want......wrong configuration from what i have been told....
BUT, that doesnt stop you sorting a 2.9 V6 block....working the heads and making some in and out bits.....low comp pistons and your away... woo hooooo...
or......are you into a bit of bobandaconker tuning.......£50 =50BHP
It's ' 2bobanaconka Tuning ' I think you'll find
It has to be paid for out of my little car bits and bobs innit .But I can draw stuff up and get it machined .Not forged pistons though ................or maybe I can ..
At some point I'm going to have to spend some money but I want to make sure it goes to the right place for the right bits .
Nothing is available off the shelf at all ,not even an uprated spring so it's research ,research, beg ,borrow and steal ( well ,so to speak )
you can easily check the cam lift of those 2 cams
http://www.lunaticams.com/Tech/Cams/CamSpecTerms.aspx
0.170"
I'm sure the 2.8 lump cams I had were a good 60 to 80 thou more
are you sure? that doesn't sound like much.0.170"
I'm sure the 2.8 lump cams I had were a good 60 to 80 thou more
Base circle 1.190" over lobes 1.360 "
See what I'm up against
I need a great pooling of minds and experience
Base circle 1.190" over lobes 1.360 "
See what I'm up against
I need a great pooling of minds and experience
any idea what the rocker ratio is, and what size valves you have?
No idea on the rocker ratio ? How would I calc that from bench measurements ?
Valves are 44 mm in and 37 exhaust
you could fit the cam and measure how far the valve opens, compared to that .17 will give you the ratio.
Nice big valves, they'll love lift. How are the port diameters?
Inlet 34 ........Ex 30.................
I've got a few days off for pissing about in the garage so I'm going to set up a block,heads and **** for measuring
is this engine out of a van?Inlet 34 ........Ex 30.................
I've got a few days off for pissing about in the garage so I'm going to set up a block,heads and **** for measuring
It's the sexiest van you'll ever see .For all it's faults
I suppose it can't be that different to the one my Dad had in his 265 Volvo Auto.It's the sexiest van you'll ever see .For all it's faults
PRV .....Should have been a V8 but the oil crisis meant they lopped two cylinders off .Hence it's pretty unique as a 90 degree V6
I just want to get the best I can from it ...I don't want to move away from the PRV as it would no longer be a GTA .
AS a non engineer then (LCA is not the same as LSA... we're engineers
how can you tell how much LATDC the cam he quoted has?
infact how can you tell how much duration the cam he quoted has?
which has more duration, a standard GTT cam, or a Piper 270?
which has more duration, a Kent RT200, or a Piper 285?
How can you tell?
Unless the figures quoted were at a specified checking height then as an educated guess I would say they had about 0.020" LATDC and also assuming (I know assume nothing, but you have to work with what you have...) that the figures given describe the designed valve motion events then 8+40+180=228.
I don't have the foggiest idea about the specifics of the cams you mention, but I know that a cam with the specs I mentioned will perform very well.
by the way, Honda NSX-90 deg V6, not really that unusual, just not common.
Do need to be careful with measuring rocker ratios. When the rocker is the follower, the observed ratio changes with the installed valve height.
Last edited by Big Jim; 10-12-2008 at 22:15. Reason: want to add to it
LSA is how far apart (angle of seperation) the centre of the lobes are.
LCA is how far off centre/tdc the lobes are.
thats rarther the point though jim, you don't have to, you can measure it.
Sorry to disagree, but LCA is Lobe Centreline Angle ie the angle between the centreline of the lobes (more usefully taken as the crank angle between the center of max lift on the exh valve to the centre of max lift on the inlet valve) , nothing to do with distance from TDC. You can have a given LCA and time it anywhere you like in relation to the crank.
LSA is just an americanism for the same thing.
And yes Scoff, as usual you are absolutely rightTNFG is a rule we should all live by. My point seems to be missed though. The valve timing specified for that volvo cam (unless it has massive and probably destructive valve acceleration - not likely) is never going to produce an particularly impressive power output.
Go on then... cam degrees not crank degrees
Last edited by Big Jim; 10-12-2008 at 23:16. Reason: oops
sure, I didn't look at the actual numbers
re the lsa business, lobe center is the real term, lca seems to have gotten lumped with the same definition somehow, I think I'd know what people ment whatever they called it
LSA, or LCA, it's all academic with asymmetric cams as the angle changes depending upon the lift you measure it at. Once again, it's all liesre the lsa business, lobe center is the real term, lca seems to have gotten lumped with the same definition somehow, I think I'd know what people ment whatever they called it
what do you mean about the lift? (know what you're getting at with the lies bit!!!) the apparent centre might vary depending on your checking height, but surely the centre of max valve lift is the centre of max valve lift, a physical property of the camLSA, or LCA, it's all academic with asymmetric cams as the angle changes depending upon the lift you measure it at. Once again, it's all lies
by lift I'm meaning checking height. So seat timing may give you 118deg LSA (what do you mean about the lift? (know what you're getting at with the lies bit!!!) the apparent centre might vary depending on your checking height, but surely the centre of max valve lift is the centre of max valve lift, a physical property of the cam
To my mind the angles between the absolute peaks isn't probably as important as the angles at which you see 1mm of valve lift. I've given up, and only worry about LATDC, then play with duration at 1mm valve lift. Maybe I'm right, maybe I'm wrong. Plotting out all those cams was very telling (btw, they will be back up on this site soon thanks to Scoff writing a sexy bit of software)
I'm liking that Hotrodding site ...It's a bit of a read so I'll have to do it in stages
http://www.popularhotrodding.com/tec.../photo_05.html
Like I guess you've discovered, cams are a bit of a black art. For lower levels of tune, its all fairly basic but when you start going for it, everything interacts and nothing is simple. I tend to go for peak lift LSA(by lift I'm meaning checking height. So seat timing may give you 118deg LSA (
To my mind the angles between the absolute peaks isn't probably as important as the angles at which you see 1mm of valve lift. I've given up, and only worry about LATDC, then play with duration at 1mm valve lift. Maybe I'm right, maybe I'm wrong. Plotting out all those cams was very telling (btw, they will be back up on this site soon thanks to Scoff writing a sexy bit of software)
Talking to the cam grinder (even though it's all lies!) should let you know what a profile is intended for.
God I wish it was simple
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