how big of a cam
- Thread starter Twisted306
- Start date
BK_CAULEY
it's built for speed not longevity, woman
as much as you want. at least that is what i have been told. and i have personally seen cams in these cars that where pretty radical. but as far as a limit i dont think there is one. im not saying this is a fact, so dont take it as one. someone on here probably knows/thinks different.
BK_CAULEY
it's built for speed not longevity, woman
thats what my brother was running an his computer. sounded mean as hell and you are right its all in the tune. his car ran like crap at first, a dyno tune and a little patience later he was movin. (after 3K RPM)
Yeah this engine is going to be nasty...Victor 2.02 headed 347, 11:1 compression. I just double checked the cam specs and i was off, it's a 624 on the intake side and 584 in the exhaust....still pretty rad though. Power band is between 3200 and 6800RPM. It'll be fun for sure.
i was told after so much Duration @50 the computer start making the motor rev up nad down acts like non mass car 302 when something out of wack
BK_CAULEY
it's built for speed not longevity, woman
The computer doesnt know what the cam is doing. the only way it could know is from the oxygen sensors, might be picking up on a lack of exhaust gas and thinking it might be leaning out, but it would have to hold open a while to get enough air in there to create a lean problem. ive never heard of one doing that but i could be wrong.
Make sure you have a decent vacuum gauge on the car because depending on how long of a duration you go with it is going to decrease the vacuum at idle enough so that the brakes dont work. I am running a cam with 236/248 @.050 and my vacuum is right around 10" at idle. You will also more than likely have to make the car idle higher than stock, mine is right around 1000-1100rpm, you need to take these in to account if you are gonna run a cam with that much duration and make it be liveable on the street, also if its an automatic a converter is definitely in order. I dont mean to go on a rant, but if you are gonna do this there are other things to take into account before doing this, and i dont think you want to spend money on something you are gonna have to take right back out.
Anthony
Anthony
BK_CAULEY
it's built for speed not longevity, woman
that could be a problem, but i thought he said it acts "like" a car that is non-mass air. not that his car was mass air.
mine is mass air i meesed up my other post PC was acting up i seen a few 5.0 with big cams at idle thay rev up and down. lot of them took off the power brakes and ran manul brakes at the end took the big cam out ran a smaller one will the stock a9p cop compuer run 245-250 @50 545-555 its a custom grind lobe center is a 112
The computer will run it, but that is a lot of duration. The duration i posted on mine is installed in a 427w. The original cam i had in mine the advertised duration was 308/318, i dont remember what the duration was @ .050 but i think it was about 245/254, but it was larger than the one i have in there now, and it had next to no brakes. I also run a PMS in my car which helps with the idle adjustments a bunch.
modusmortis
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- Aug 3, 2006
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with some of the wilder cams where idle quality becomes an issue, the iac can have trouble smoothing out the idle due to the natural lope of the cam. hence, surging idle.
Well, the computer does think it knows something about the cam...
There is a setting for 'Injector Timing'
This setting (a table) determines when the injector for each cylinder fires.
Firing the injector when the exhaust valve is still open can result in spraying fuel directly out the exhuast valve.
The ecu has already calculated the 'correct' pulsewidth, but with some of the fuel dumping out the exhaust, you may end up with a lean mixture in the combustion chamber?
Also, when the fresh air and fuel charge hits the O2, the O2 will read lean.
These are some of the reasons that large overlap cams can cause efi issues...
I'm not sure on that though... there are more factors there than I care to think about right now... 3/4 into a six pack...
Instead of asking 'How much cam can the ecu handle?'
Ask something like 'What cam specs will provide the results I'm looking for?'
Duration is a function of the valve events. A cam designer will select the valve events, and then calculates the duration @.006 and @.050 from the open and close events.
Duration on its own is pretty useless.
If you are SERIOUS about getting the RIGHT cam for your setup...
Look up Jay Allen
http://www.camshaftinnovations.com/
Or see the 'Custom CI Cam' link in my sig...
(guess where my cam is coming from!!!!!!!!!)
Random thoughts,
jason
There is a setting for 'Injector Timing'
This setting (a table) determines when the injector for each cylinder fires.
Firing the injector when the exhaust valve is still open can result in spraying fuel directly out the exhuast valve.
The ecu has already calculated the 'correct' pulsewidth, but with some of the fuel dumping out the exhaust, you may end up with a lean mixture in the combustion chamber?
Also, when the fresh air and fuel charge hits the O2, the O2 will read lean.
These are some of the reasons that large overlap cams can cause efi issues...
I'm not sure on that though... there are more factors there than I care to think about right now... 3/4 into a six pack...
Instead of asking 'How much cam can the ecu handle?'
Ask something like 'What cam specs will provide the results I'm looking for?'
Duration is a function of the valve events. A cam designer will select the valve events, and then calculates the duration @.006 and @.050 from the open and close events.
Duration on its own is pretty useless.
If you are SERIOUS about getting the RIGHT cam for your setup...
Look up Jay Allen
http://www.camshaftinnovations.com/
Or see the 'Custom CI Cam' link in my sig...
(guess where my cam is coming from!!!!!!!!!)
Random thoughts,
jason
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