Cam timing corrected, now seeing less boost... - Page 2 - Boost Forum

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Re: Cam timing corrected, now seeing less boost...
Wednesday, July 17, 2013 10:11 AM
Yes, but the relationship of when the piston moves compared to when the valve opens is still different.






Re: Cam timing corrected, now seeing less boost...
Wednesday, July 17, 2013 10:15 AM
Zs Z wrote:

-Z Yaaaa- wrote:

i guess the LO cams make the engine that much more efficient. its not really that surprising when you think about it though as they really are basically the same thing as HO cams but a little bit smaller.


That is the silliest thing that I have heard you say brad. .035 lift and 12 duration at 50 are quite a bit in the world of cams, especially the smaller the engine, not to forget that the valve event timing are probably totally different. LO cams were for regular people everyday vehicles the HO cams were performance driven design.

I will agree that the drop in your PSI does suggest more efficiency and rightfully so as they are more agressive cams than factory LD9 cams and the change in your timing allowing more valve overlap, or valves opening at same time. This is engineered to cause a scavaging effect for upper rpms. So basically you are loosing boost through the exhaust but gainimg power because more cfms are moving through the engine. I am interested to see track times. Just an interesting side note, this is the reason you dont want too much overlap in a turbo application. There is so much pressure in the exhaust manifold that reversion can occur and actually blow exhaust into the intake manifold.

The only other thing I can think of that could be reason for the lower psi than others is that you have the od crank pulley and smallest snout pulley and it is possible that you are overspinning the bejesus out of it and pushing it way past its area of efficiency. I hope that is not the case though.


yes, i will still stick with the statement that they are just a bit smaller. the difference is minute and barely even worth arguing over. will it mean more power with HO cams, you bet but the difference between the LO engine and HO engines werent that much. and the LO engine got the smaller head and smaller intake manifold to so keep that in mind. (and yes i realize some had an 086 and HO manifold but im talking about factory ratings with the correct heads/manifolds here)

its overspinning a lot, yes... however, its not overspinning it any more than it was before the cam timing was corrected. and really, i am only down .100 in pulley sizes over what john's setup is and he sees like 12 psi on secret cams. we have the same blower port work as well. i attribute some of his higher boost levels to him being in flordia at sea level though. overspinning really doesnt mean much when you have meth/water injection. it becomes out of its efficency range because its blowing more heat and losing more power because of it. if you can keep the iat's cool you could spin the ever living ish out of it and make gains yet. we simply cannot do much more on the pullies. i MIGHT be able to get a 2.35 pulley on the snout, MAYBE. and i suppose if we ditched a couple bolts on the timing chain housing cover and clearanced it some you could maybe get a larger crank pulley on it... but i believe doing the lightweight rotors and venom cooler is going to help ten fold over doing even more pulley size changes so thats the route i am taking.

i really think the cams need to be mated together as they were from the factory in order to get the best results. LO cams together, LD9 cams together, HO cams together. secret cams are garbage... just my opinion.

i have noticed a dramatic decrease in IAT's after this as well. this tells me the blower isnt working as hard as it was before. before i could get over 200* iat's and crusing temps around 130*. now its around 100* crusing and 140-150* during a pull (this is off meth/water).. on meth/water it gets cooler than it did before.



M45/OS crank/2.4 snout. Now with 5 speed! It's nice to be injected but I love being blown!
Re: Cam timing corrected, now seeing less boost...
Wednesday, July 17, 2013 10:16 AM
-MD- Enforcer wrote:

Yes, but the relationship of when the piston moves compared to when the valve opens is still different.


right and think about the ignition timing as well, it was off too.



M45/OS crank/2.4 snout. Now with 5 speed! It's nice to be injected but I love being blown!
Re: Cam timing corrected, now seeing less boost...
Wednesday, July 17, 2013 1:16 PM
-Z Yaaaa- wrote:

-MD- Enforcer wrote:

Yes, but the relationship of when the piston moves compared to when the valve opens is still different.


right and think about the ignition timing as well, it was off too.


Exactly. Since the intake valve was probably closing earlier you probably were seeing the pressure build in the manifold and not really in the cylinders.

Do you run a cam position sensor or is it all done off the crank? If its all off the crank your ignition timing still should have been right.



Re: Cam timing corrected, now seeing less boost...
Wednesday, July 17, 2013 1:47 PM
we have both however i dont see how it could be right if the hardware was in the incorrect place when the ignition timing fired. technically the ignition timing was correct in terms of when it fired electronically, but because the cam timing was IN-correct it in turn also made the ignition timing wrong for where the cam events happened.



M45/OS crank/2.4 snout. Now with 5 speed! It's nice to be injected but I love being blown!
Re: Cam timing corrected, now seeing less boost...
Wednesday, July 17, 2013 3:49 PM
Ignition timing is denoted with respect to the bottom end (15 degrees BTDC etc). But some of the time its pulled off of the crank and some times off of the cam. Like if you have a Honda SOHC engine a tooth off your timing would be off because it reads the cam position via the distributor then assumes the crank position and fires the plugs that way. So youd be firing retarded or advanced from the proper position of the crank BTDC. If the computer is basing it off of the crank, it will fire the plugs at the same position BTDC no matter where your cam is.

I hope that explanation makes sense. I ramble a lot. Haha.

Now Im curious how it didnt pop a CEL for that. The computer should have noticed a mismatch in the position of the cam and crank. Silly GM.



Re: Cam timing corrected, now seeing less boost...
Wednesday, July 17, 2013 4:53 PM
i dont think you are understanding what i am getting at.

say cams are at X postion moved advanced or retarded 1 tooth via the crank being off like mine was. cams events happen (just an example) 15* sooner or later than they are supposed to be. the ignition timing does not know this as i am pretty sure the cam position sensor only has to do with the way the fuel injectors fire. (batch fire vs sequential). so, saying the cam sensor has no bearing on ignition timing, the spark plugs are going to be firing where the PCM is programmed to have them fire per the crank's position sensor.

crap, come to think of it the ignition timing wasnt even firing where it was supposed to be... the crank was out of time a tooth, remember? wow i never thought of it like that.... but yes thats true as well. not only was the ignition timing off from where the crank was positioned, but it was also off when compared to the cam events as well.. or hell maybe it was actually in the right place because the crank was off but then since the cams were also off it might have make it back to straight up?

confusing as a mofo! LOL



M45/OS crank/2.4 snout. Now with 5 speed! It's nice to be injected but I love being blown!
Re: Cam timing corrected, now seeing less boost...
Wednesday, July 17, 2013 5:28 PM
Time to just accept it and move on..
Re: Cam timing corrected, now seeing less boost...
Wednesday, July 17, 2013 6:06 PM
Hahaha I think we're actually agreeing with each other but getting there different ways.



Re: Cam timing corrected, now seeing less boost...
Wednesday, July 17, 2013 6:07 PM
Philly D wrote:

Time to just accept it and move on..

haha I dunno I'm diggin the conversation.



"In Oldskool we trust"
Re: Cam timing corrected, now seeing less boost...
Wednesday, July 17, 2013 6:14 PM
Basically what Im getting at is dont think of it as your crank being out a tooth, think of it as both of your cams being out a tooth and your crank being where its supposed to be. Your PCM only knows where the crank is via the reluctor wheel. Your ignition timing relative to the cams was out but cam events have no bearing on your base ignition timing. All they do is affect how your cylinder fills and empties.

I could flip the cams 180 degrees out and the plugs would still fire at 20 degrees BTDC or whatever the PCM is set at.




Re: Cam timing corrected, now seeing less boost...
Wednesday, July 17, 2013 8:45 PM
yea but the crank WAS off a tooth, thats the thing. there is a dot on the timing chain housing that is supposed to line up 100% straight to the keyway/dot on the crank. this was off.



M45/OS crank/2.4 snout. Now with 5 speed! It's nice to be injected but I love being blown!
Re: Cam timing corrected, now seeing less boost...
Wednesday, July 17, 2013 8:54 PM
But the reluctor wheel doesn't move, it's welded to the crank. Regardless of timing chains it will always be at the same spot in relation to the pistons unless you machine it off and weld a new one on.

Edit: and by welded I mean bolted because it's not an eco so the trigger is on the crank pulley. But still, the idea is the same.


Edited 1 time(s). Last edited Wednesday, July 17, 2013 9:04 PM


"In Oldskool we trust"
Re: Cam timing corrected, now seeing less boost...
Wednesday, July 17, 2013 9:14 PM
^^^This guy. He gets it.



Re: Cam timing corrected, now seeing less boost...
Thursday, July 18, 2013 3:15 AM
For all intensive purposes. The PCM doesn't know the crank was off a tooth, if anything, it may know the intake cam timing is not exactly where it should be. The PCM thinks the crank is correct 100% of the time. It has no idea where the exhaust cam is.







Re: Cam timing corrected, now seeing less boost...
Thursday, July 18, 2013 3:18 AM
I know my timing in my LG0 motor is intake 2 degrees advanced, and the exhaust is 2 degrees retarded.





Re: Cam timing corrected, now seeing less boost...
Thursday, July 18, 2013 3:45 AM
They are correct the crank is always going to be right.

Even if you try and purposely set the crank to be 1 tooth off, and the cams also, as far as the computer knows when the crank position sensor see's the mark on the trigger wheel if when it decides what to do.

Only way to change this is to move the trigger wheel from where it is suppose to be to fool the ECU. Of course this would likely cause many more problems.



FU Tuning



Re: Cam timing corrected, now seeing less boost...
Thursday, July 18, 2013 3:51 PM
see i told you guys it was confusing LOL now it makes sense...

lol back to the cam timing though, they were definitely off and now i am enjoying a lazy supercharger. 6-7psi with maxed out pullies. thing is on vacation hahaha i wonder if its going to boost at all once i get a real flowing exhaust via cutout, ported head and even larger cams.



M45/OS crank/2.4 snout. Now with 5 speed! It's nice to be injected but I love being blown!
Re: Cam timing corrected, now seeing less boost...
Thursday, July 18, 2013 6:23 PM
Looks like youre gonna need an m62 bud.



Re: Cam timing corrected, now seeing less boost...
Friday, July 19, 2013 5:47 AM
i just so happen to now own the technic m2 setup. only one problem, i hate how the blower is set up. they did it so you had to use a second pulley system. if i can figure out how to put a real m62 (not a gen 3 bonneville one) on top of the manifold and have it moved over so you can use one pulley system then ill probably use it.



M45/OS crank/2.4 snout. Now with 5 speed! It's nice to be injected but I love being blown!
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