Wades SnS

iTrader: (2)

I have been reading for several days about dynamic cylinder air and compresion but I haven't found an answer to my ?'s yet. I have a comp cam 236/236 .602/.602 114+2 xer lobe cam sheubeck lifters port/polished 5.3 heads unmilled with 2.02/1.60 valves that flow similar numbers as ls6 heads. Also running stock maf with screen and tb through ls6 intake. Stock bore motor. Long tubes into dual 3" exhaust into dynatech cats through spintech mufflers. It is a stock bore/stroke motor. Now that you have a little back-ground on to my problems. My understanding of dynamic cylinder pressure is that in a nut shell it is th amount of air that flows into a given cylinder and should be around .75g/cyl or so on a stock motor and more on a camed motor. My reading flattens out at 4200 rpms at a whopping .62g/cyl and climbs to .69g/cyl at 6900rpms. So my first thing that I assume is that its my air box seeing as its design isn't the greatest(not a lot of room in a s-10) so I decided to take everything off from the tb forward. So I run through the gears logs some more data and now from 4200 to 6900rpms I am up to .75 g/cyl? Anybody have any ideas as to what it could be? I read at one point in time people where having trouble with something flattening out on a dyno due to improper lifter clearance but I have check that and it is what it is supposed to be. Could it be my tune? Improper timing?(mine is mostly stock) Need for a ported tb? Could it be the cam? Map is 97kpa at WOT. I am lost and don't really know where to turn. I did do a compression test when I first built the motor but I am unsure of the value now but all cylinders where within a few pounds of one another. Sorry for the novel just wanted all info to be known.

Thanks,
..RJ..

Wades SnS

iTrader: (2)

Is there anyone that has any ideas on what is wrong? Someone has to have some info of some sorts or something else to try. I am up for suggestions

DramaFoYoMama

Are you tuning off the MAF? If so, shame shame on you. Try putting it in speed density and try again. You'll have to recalibrate your MAF to get correct readings.

Slowhawk

iTrader: (12)

Your inlet is a major restriction.

Wades SnS

iTrader: (2)

I have my MAF fail set to 0 so I am in sd. SO what you are saying is calibrate the MAF then see what I get, ok I'll try that.

Slowhawk what are you saying when you are saying my inlet is a major restriction? That the change without anything in front of the tb is a significant one and is my problem or that using a stock screened maf and stock tb w/ a ls6 is to much of a restriction? Please explain.

ringram

You need a good tune first. Check your VE is dialled in 100% and your AFR and spark is good. Then start worrying about g/cyl.