The thing I like to always bring up though, is that you can't truly credit most of the gains to the longtubes here because of the differences in the a/f. Meaning, how much was gained by simply correcting the a/f and how much was gained by longtubes alone?
well thats just it. the first set of numbers were pretty much without a tune after adding the l/t. the second set is after tuning for the l/t. l/t's are a mod that should be tuned after. ofcourse the tune gives it some power. that is the case with all mods. if the a/f is not corrected you are not gaining the full power. you can see the difference. peak was almost the same, but the tune fixed the numbers the way they should be, making the l/t much more torquey.
the car stock has the correct a/f so after a mod you should correct a/f and that is the power made by adding the mod.
THANKS MAN...the pic works now . Those are definatly some great gains down low, and up top!!!!
And jstreet, he already had a tune BEFORE the LTs...they gained that much even though they screwed up the A/F...then when the A/F was corrected again, thus the new #s.
One thing though man...it looks as though your power is dropping pretty quick up top before the LTs...those cams must really be mild . How does it feel up top? And what RPM do you shift at?
Just curious because I cant feel any drop in power whatsoever until past 6200. Before the cams, it only dropped 10HP from 5600-6K, and I could feel that pretty easy. Looks as though it wanted to start giving out...but the LTs DEFINATLY helped out up there.
EDIT: Oh, sorry but was the A/F @ 14 ALL they way through, or just down low?
they are very mild. i basically want a very fast street/show car. it will prolly never see the track. i still dont shift any higher then 6000 rmp, only be accident. they just basically serve as an upgrade to the pi cams that come with the car. just to get some more power. they are also set up for a blower. thats about it. they peak at 5700 rpm at 290 rwhp and at 6000rpm they are at 284rwhp. i looked at my dyno sheet again, and what i posted at 5900 rpm is a little low. so it drops about 6 hp from peak to 6000.
well thats just it. the first set of numbers were pretty much without a tune after adding the l/t. the second set is after tuning for the l/t. l/t's are a mod that should be tuned after. ofcourse the tune gives it some power. that is the case with all mods. if the a/f is not corrected you are not gaining the full power. you can see the difference. peak was almost the same, but the tune fixed the numbers the way they should be, making the l/t much more torquey.
the car stock has the correct a/f so after a mod you should correct a/f and that is the power made by adding the mod.
A correctly tuned car should not need a retune after longtubes are added. Nothing about longtubes inheretly changes the MAF reading. Usually tuning changes for lt's are around the o2 pulse delays to correct for the o2's being futher downstream. But if your a/f was good before the lt's then you are correct about the gains from the headers. Good numbers either way.
not to change the subject or anything but I am in the process of putting on mac longtubes. The only mods I have are pi motor, prochamber, flowmaster c/b, and CAI. I do not plan on tuning the car after putting on the l/t's, do you think my car will be running lean? Thanks
^ Not much of a chance...I really think the plenum/TBs are the main culprits...BUT the CAI WILL flow better than stock and can lean it out somewhat. Your A/F SHOULD be about perfect right now.
hotmustang, i didnt read what you were saying carefully on my last reply. i see what you are saying. i was looking at the dyno for my current numbers not the one with just the heads and cams. yea the headers did help up top for the power falling off.
also what i forgot to tell you, is that the cams were custom for low to mid range, so that is why they die off early too. most people that upgrade cams, lose low end and gain up top. after my cams i had only gains from 3000 rpm all the way up. as aposed to before the heads and cams.