mogs01gt said:thanks man, I thought the B heads were the good ones.
johnny98 said:yea, leaning out is what i would have expected as well. but every time they made it more rich, it got more power. it didnt want to be lean at all. (much to the shock of everyone in the shop).
the CR as advertised by SHM should be between 10.25 and 10.5:1. however, oddly, the Manley website lists the CR for my pistons at 10.96:1. is there a way to determine the compression of an engine after its built?
the intake and exhaust lift is 0.452.
duration @ .050 intake and exhaust is 209.
thanks everyone.
tontot77 said:I guess go more psi instead of ci's...
are you referring to the A/F ratio being 11.0:1 or the compression ratio? either way, yea, i would have expected leaning the compression ratio out would give it more power. that is the general rule of thumb. that was the first thing they tried to do when tuning it, and it lost power and detonated like a muthaf***a. however, the more rich it got (up to 11.4), the more power it produced and without any detonation.RedGTvert said:I kinda thought it would be 11.0:1 area. Maybe you have it backwards, leaning it out will give it more power. Which software was it tuned with.
Don't get too frustrated. Sometimes you need to play with the combo to get it right. Just throwing parts at it, does not automatically mean big gaisn, unless they work well together.
johnny98 said:are you referring to the A/F ratio being 11.0:1 or the compression ratio? either way, yea, i would have expected leaning the compression ratio out would give it more power. that is the general rule of thumb. that was the first thing they tried to do when tuning it, and it lost power and detonated like a muthaf***a. however, the more rich it got (up to 11.4), the more power it produced and without any detonation.
it was tuned on a dynojet, and the only thing i saw on the computer was a program called 'winprep' or something like that.
what would cause the a/f to need to be that rich though? that is what i still dont understand, and SHM doesnt have an answer for it either. the timing is at stock. when they tried to advance it, it started detonating again. SHM recommended the stroker and cam combination, and when i told them i was planning on a stage one head port, they said that would be even better. i was planning on a blower, so it is all kinda sad...RedGTvert said:Yes, guess the reason you got detonation when trying to lean it out was that 11.0:1 CR you are running. I am just wondering if they have a tad too much timing.
This is why I said, you cannot just throw parts at a car to make lots of power, unless the parts are matched real well. I am guess you called SHM, and asked for recommendations and this is what they gave you, so you bought it. I am still surprised that 11:4 is the leanest you could go, but with that CR, it limits you N/A. On a positive note, nitrous loves that type of CR, so if you were to go with this type of power adder, look out for the numbers then.
PS. I have seen 99/01 Cobras make 600+rwhp and 420+tq. Like I said, these things are not TQ monsters unless you have something on there like a 2.2L KB. I still say your numbers are not that far off. With a better tune, maybe 10 more rwhp.
Yeah, you are right. That is what I was thinking. The B heads are the ones wanted for Forced induction.RedGTvert said:Don't take me wrong, they are not bad heads. They flow decently, but lack the velocity of the c's or 03/04 heads. They do very good with FI, but N/A they cannot keep up with an equal set of 03/04 heads.
Dan_Soprano said:those numbers are pretty damn respectable in my book for a N/A 2 valve 4.6 bro........
Manny's only thought was that it could be just a bad head/cam combination. not much input other than that.Red35th said:I still think that your numbers are 30hp low, but I have no idea why. Did HPP have any answers? Manny campaigns a 4v in NMRA if I recall correctly.
Yes, Dan Soprano, if this were a 2v with these numbers n/a, i would be quite the happy camper. it is a 4v, however, leading to my quandary.69fb00GT said:It's a 4v
I would have the tuner take out timing and lean out the a/f. If that baby has some big ports you're gonna need more cam and more rpms to make the power you're looking for. Plus the bigger cams will help bleed off your cylinder pressures which is causing your detonation.
johnny98 said:what would cause the a/f to need to be that rich though? that is what i still dont understand, and SHM doesnt have an answer for it either. the timing is at stock. when they tried to advance it, it started detonating again. SHM recommended the stroker and cam combination, and when i told them i was planning on a stage one head port, they said that would be even better. i was planning on a blower, so it is all kinda sad...
but, they are still decent numbers, and it drives well.
any ideas, anyone?
Red35th said:That compression is pretty high to run on 93 octane. To cope with this they could either lower the timing, or the a/f ratio. They clearly chose the latter. The main problem is that your a/f ratio is quite high for a daily driver car on pump gas.
I am still trying to find the thread of a guy with a 96-98 Cobra. He had full bolt ons, longtubes, Dr. Gas offroad X pipe. Tuned by MPH in GA it put down 300rwhp, it had NO internal/headwork/cams done to it at all.
I still think that your numbers are 30hp low, but I have no idea why. Did HPP have any answers? Manny campaigns a 4v in NMRA if I recall correctly.
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