_Bomber Watson_
Posted 30 April 2014 - 07:05 PM
Explain which part? Thought it was a pretty straight forward statement.....And dont feel like typing a 4000 word encyclopedia explaining the whole thing....
Johnsey, wheres you IO degreed at?
Cheers.
Edited by Bomber Watson, 30 April 2014 - 07:07 PM.
CABIN ENGINE CONTROLS GALORE
Posted 30 April 2014 - 07:57 PM
Hey Ryan,
Dynamic Compression Ratio is when the Cam lobe shuts the Valve,
and what Volume of the Cylinder is left as the Piston is Rising is the C.R. available ( so a Big cam has less Volume left as opposed to a small Cam ).
A small cam cannot rev as high as a big cam can.
But that is where DJ is explaining how unheard of Cam Profiles ( with their Hi Lift Profiles etc ) can have the best of both Worlds. Dave I
What do you mean by this? Can you please explain further? Thanks
Another Holden 6 tragic
Posted 30 April 2014 - 08:04 PM
_Bomber Watson_
Posted 30 April 2014 - 08:04 PM
Dun worry i made a typo anyway mate, I ment IC, Inlet Closing. To work out your dynamic we need to know when the inlet valve closes, as Dave explained.
But with that kind of duration (similar to my cam) you should be fine at 11.5 on 98 i recon.
So long as your not running some ridiculous amount of total advance.
If i was building the engine for spray i probably would have went a touch lower to, personally. Moreso for tuning leeway.
Cheers.
Edited by Bomber Watson, 30 April 2014 - 08:06 PM.
_gorto_
Posted 30 April 2014 - 08:39 PM
Hey Ryan,
Dynamic Compression Ratio is when the Cam lobe shuts the Valve,
and what Volume of the Cylinder is left as the Piston is Rising is the C.R. available ( so a Big cam has less Volume left as opposed to a small Cam ).
A small cam cannot rev as high as a big cam can.
But that is where DJ is explaining how unheard of Cam Profiles ( with their Hi Lift Profiles etc ) can have the best of both Worlds. Dave I
Thanks Dave, that's all I wanted to know.
So the bigger the cam, the lower the dynamic compression, comparatively to a smaller lift cam?
There are a few running 12:1 on pump 98 with no detonation to my knowlege.
Keep in mind a lot of guys are running cam profiles that would be unheard of in a big block short of a pro street engine, dynamic comp ratio is the key.
Cheers.
Are you suggesting that the cams in these 202's are larger (in duration I'm guessing?) than dad's big blocks? If so, I doubt it..
Edited by gorto, 30 April 2014 - 08:40 PM.
_Bomber Watson_
Posted 30 April 2014 - 08:59 PM
Well dont leave us hanging, show us the cam specks for your old mans big block?
FFS you come into this thread, make a comment thats pretty out there almost stating that no Holden six could handle what's being discussed in the thread on pump gas because your old mans big block which is an entirely different engine with an entirely different chamber etc and with absolutely no info on the engine cant do it, then proceed to get antsy when i point out a simple fact?
Cheers.
Another Holden 6 tragic
Posted 30 April 2014 - 09:03 PM
_gorto_
Posted 30 April 2014 - 09:31 PM
Well dont leave us hanging, show us the cam specks for your old mans big block?
FFS you come into this thread, make a comment thats pretty out there almost stating that no Holden six could handle what's being discussed in the thread on pump gas because your old mans big block which is an entirely different engine with an entirely different chamber etc and with absolutely no info on the engine cant do it, then proceed to get antsy when i point out a simple fact?
Cheers.
I'll get them tomorrow.
I didn't say that, I ASKED if it could handle it as like many others, I am also building a 202 and am up to the stage of choosing comp and would like to get some info of other forum members that have experience 1st hand, eg yourself, and SA EH. The whole reason I joined this forum is to get more info. I'm sure at some stage you were like me and didnt know much either. So sorry for not being a frOcking expert on engines, bomber.
_Bomber Watson_
Posted 30 April 2014 - 09:36 PM
Dad has a 588c.i BBC in his monaro, 11.27:1 comp. He recently had it rebuilt and engine dynoed by the guy who is building my 202. They had to get a digital ignition and pull ignition out arouuuuund about 2500-3500rpms, at a guess. then feed it back into it to avoid detonation.
I couldnt imagine a 202 having very good resistance to detonation considering their chamber design. If dads was detonating at 11.27:1, surely a 202 would at 11.5:1?
Are you suggesting that the cams in these 202's are larger (in duration I'm guessing?) than dad's big blocks? If so, I doubt it..
Sorry mate, must have taken you the wrong way, i saw them as statements.
Hard to portray emotions and body language over typed media.
In the first quote you use the term "considering there chamber design"
This put me under the impression you were rather knowlegable in these kinds of things?
As i said, must have taken you the wrong way.
And your dead right, I didnt even know what a compression ratio was when i joined this forum 12 years ago, but its all been covered in depth in several threads since then.......
Cheers.
Edited by Bomber Watson, 30 April 2014 - 09:38 PM.
CABIN ENGINE CONTROLS GALORE
Posted 30 April 2014 - 09:40 PM
So the bigger the cam, the lower the dynamic compression, comparatively to a smaller lift cam?
almost right Ryan,
Bigger Cam has less D.C. yes, but you can increase the D.C. by shaving to get it back, and the small cam can be the same lift, but it it the duration of the cam is what makes it a small cam. Dave I
_gorto_
Posted 30 April 2014 - 09:40 PM
Sorry mate, must have taken you the wrong way, i saw them as statements.
Hard to portray emotions and body language over typed media.
And your dead right, I didnt even know what a compression ratio was when i joined this forum 12 years ago, but its all been covered in depth in several threads since then.......
Cheers.
No worries.
Not at all, definitely questions. Plenty of people on here that know more than me, just trying to extract a bit of info for my build.
Thanks, Ryan
Another Holden 6 tragic
Posted 30 April 2014 - 09:42 PM
_gorto_
Posted 30 April 2014 - 09:42 PM
almost right Ryan,
Bigger Cam has less D.C. yes, but you can increase the D.C. by shaving to get it back, and the small cam can be the same lift, but it it the duration of the cam is what makes it a small cam. Dave I
Did a little bit of research, I seen that it is the duration (more importantly overlap) of the larger cams that reduces D.C as obviously there is no compression while the inlet is open, its once the inlet closes that the compression starts, therefore less of the piston stroke is left, therfore, less dynamic compression. That right?
CABIN ENGINE CONTROLS GALORE
Posted 30 April 2014 - 09:43 PM
yes
_gorto_
Posted 30 April 2014 - 09:44 PM
Ryan mate ,here's my advice... I'm guessing you've got a pretty good idea of what you want out of your 202 right? Use all the info around you as a guide, refer back to it as often as you like, and stay to your budget.
I for one am not super human & will happily confess to not knowing everything about combos, but stick to what you want bud, not what people tell you...
Alrighty, I'm done.
Thanks mate, appreciate it.
budget? blew that as soon as I bought the bloody lc haha
CABIN ENGINE CONTROLS GALORE
Posted 30 April 2014 - 09:45 PM
you can still have less overlap on a big cam
_gorto_
Posted 30 April 2014 - 09:48 PM
you can still have less overlap on a big cam
When you say 'big', you talking about lift?
Anyway, gettng off track on Jonesy's thread..
Im off, talk later lads. Thanks for the info
_STRAIGHTLINEMICK_
Posted 30 April 2014 - 09:49 PM
Sorry Bomber, my what degreed at?
Gotcha now.
Inlet 19/53
Exhaust 59/21
So Jonesy are these the numbers you saw on the degree wheel at .050' lifter rise and if so are they what was recommended on the cam card ?
_Bomber Watson_
Posted 30 April 2014 - 09:51 PM
Ryan mate ,here's my advice... I'm guessing you've got a pretty good idea of what you want out of your 202 right? Use all the info around you as a guide, refer back to it as often as you like, and stay to your budget.
I for one am not super human & will happily confess to not knowing everything about combos, but stick to what you want bud, not what people tell you...
Alrighty, I'm done.
Couldnt have put it better.
I've been reading your build thread Ryan, its impressive, and way beyond what i acheived when i was your age making $100 a week working at big w...
When i started getting bigger dollars i made the same mistake i think you might be doing, I trusted an engine builder who had some very very good times and some very impressive hp figures under his belt.
Turns out although he was great with other engines he wasnt totally akin to holden sixes....
This mistake is costing me a LOT of money i really dont have (mortgate, other toys, etc) to rectify as we speak.
Question, question, question.......
Cheers.
Edited by Bomber Watson, 30 April 2014 - 10:00 PM.
Another Holden 6 tragic
Posted 30 April 2014 - 09:58 PM
_Bomber Watson_
Posted 30 April 2014 - 09:59 PM
Sorry Bomber, my what degreed at?
Gotcha now.
Inlet 19/53
Exhaust 59/21
Yeah, missed this one, otherwise engaged hehe. .
53 degrees intake closing after bottom dead center sounds awefully low for the duration your saying you have?
Cheers.
CABIN ENGINE CONTROLS GALORE
Posted 30 April 2014 - 10:02 PM
lift is before the Valve shuts Ryan,
it is when the valve is shut, is the compression, and the duration is the lift height and lift speed in-between Mate.
A small cam is a shorter duration compared to a big cam, which is the longer duration. Dave I
CABIN ENGINE CONTROLS GALORE
Posted 30 April 2014 - 10:13 PM
Duration is the Time the Valves are open
_gorto_
Posted 30 April 2014 - 10:14 PM
Couldnt have put it better.
I've been reading your build thread Ryan, its impressive, and way beyond what i acheived when i was your age making $100 a week working at big w...
When i started getting bigger dollars i made the same mistake i think you might be doing, I trusted an engine builder who had some very very good times and some very impressive hp figures under his belt.
Turns out although he was great with other engines he wasnt totally akin to holden sixes....
This mistake is costing me a LOT of money i really dont have (mortgate, other toys, etc) to rectify as we speak.
Question, question, question.......
Cheers.
He may seem this way, but he has quite a bit of experience with holden 6's. A lot of it passed down from his father, who used to build group NC 202 engines. He has since taken over the shop and is still involved with circuit racing. I think he does a lot of balancing work for a few of the nc 202's. Still in the know, dont worry about that
lift is before the Valve shuts Ryan,
it is when the valve is shut, is the compression, and the duration is the lift height and lift speed in-between Mate.
A small cam is a shorter duration compared to a big cam, which is the longer duration. Dave I
think I understand now, thanks dave
_Bomber Watson_
Posted 30 April 2014 - 10:15 PM
Well then why bother asking questions here?
0 members, 2 guests, 0 anonymous users
