OK, this thing is starting to really aggravate me.....

the air stayed pretty constant all night, as did 60' times....and my

MPH was all over the place as were my ET's.....i think this might be the most inconsistant car on the planet.....

i've been using the 2-step so i should be right there everytime and its not.

last outing at the track netted me passes from 12.50's all the way to 12.90's

trap speeds went from 112's to 109's

engine temp is constant at about 150 on every pass too.

any brain pickings would be appreciated

 

wish i could help ya man, that cars pretty sweet tho. th bullet hole adds charector, still cant get over that.

 

When you said the air stayed consistent, was that a "it felt the same" or did you actually have a weather monitor/station to note this. I've seen it when the air "feels" cool/er but actually the humidty goes way up, does'nt feel real humid, but it is and it changes the DA big time which would throw off E.T.'s and mph off. Was this a race or TT you were at, how long did you wait before making another run from the preivous run, when the car cools off too much it can slow you down a wee bit, and when they get real hot doing back to back runs, alot of times they'll slow down a tad.
Now, I'm not insulting you but I seen the 5 speed in the sig. Was every pass shifted at the same rpm as far as you know, same speed shifting gears as the last pass, I've seen guys bangin gears run more consistent than auto cars, but then I've also seen alot of other manual cars run all over the place because of shifting.

 

the air was about the same, i checked with one of the pro guys who was running that night....he was dialing his 9.0x second monte in....he has a weather station.....

the passes were all about 30 min apart.....the car was at the same temp for all the passes including the 1st pass.

It was a street night which is just like a test and tune really.

i shifted the car at 6000rpm every pass, there was only one pass that i missed a shift and it was like a 13.5 cause i just let off after the missed shift.....im pretty on with the shifter too, im sure im not the best there is (i know im not) but im not all over the place.

so like i said.....weirdness

 

Another thing, maybe not a factor, but were all passes from the same lane? Sometimes the roll out might be a shade different-not enough to add up the difference of .00-.40, but there are times when lanes will change and passes will be faster/slower. .4 is an awful large difference per pass, on your time slips, how consistent were your 60', 330', 1/8th mi. and 1/4mi. Compare these numbers and see exactly where in the track that you lost or gained and then also compare lanes with the times and see what you come up with. Usually in an ideal situation most cars hardly vary on the big end, usually the goof ball numbers come right outta the hole or a short ways out. Once you've got these numbers, let me know what you came up with. Guess from personal experience the 60' and 330' mark are the ones that tend to vary the most when I'm at the track depending on my burnout and track prep, our track is funny like that,especially on TT, I'll vary the 60's anywhere from .02-.06 and that screws up the whole pass and forces me to get out the dart board when deciding on a dail.

 

thats where it gets weirder.....my 60' times are a bit all over the place, due to the lack of traction compound and hondas dragging water all over the pad......but everything seems to even out by the 1/8 and my trap speeds are alllllll over the place, which is what aggravates me.

if my et's were all f-ed up and my 60's were up and down due to track conditions that would be fine as long as my trap speeds were all on the same planet.....but varying from 109-112.5 +?

thats just downright freaky

 

The other car i race-truck actually-is kinda doing the same thing your describing and it does suck come race day. This thing never hooks on a T&T-never, even on race day I have to shred the tires to try an achieve a "decent" launch. My 60's will vary from 1.45 all the way to 1.52, but believe it or not most runs wether it be a 10.71 pass to a 10.80 pass, the mph are almost identical-go figure. You would tend to think given the difference in 60's and overall E.T. that the mph would show up different, but most of the time it's in the high 122.?? to 123mph and that's it. I gave up on mph and just use that as a guage to tell me if the convertor is working properly, and use the 60', 330' and 1/8mi. to predict my dial in's. I'm kinda at a loss as to what else it might be. I think I've thought of the common stuff, but maybe your right-that's car is frickin weird!!
But let's try this maybe. Okay you said by the 1/8 everything is pretty much even on all slips, I'll assume within .03 of each other for ET and .05 mph. This being said, usually after the 1/8 mi. nothing but brute hp is pulling your car, if we think of it simnple like that maybe we can come up with a motor theory as to why you'd be dropping off mph or gaining in that big of an increment. Maybe there might be a fuel delivery problem-obviously not a huge problem, but maybe just enough. Assume all filters are new and up to the task, using good gas and none of that Ethanol crap. If you still have the computer controlling stuff, is it possible on of the sensors might be giving false reading on air/fuel mixture possibly causing a rich or lean condition at a certain point. What about your ignition system. Is the distributor working properly, bringing in the timing at the rpm you've chosen, is it holding this timing even after you've reached the "all in" rpm and not jumping around. Are the distributor internals up to par, all the bushings still tight and not letting the armetures flutter around. Plugs gapped the same and looking good, maybe check all 8 to see what they're telling you, maybe some cyliders are running a little richer than others or leaner-what ever. Some of these ideas may seem a bit out there for the situation, but hey we're brain stormin!! I think I've finally thought of all the things that may seem to paly a role into the big picture, but anybody else reading this please jump in and give your 2 cents.

 

i did have the fuel delivery theory....the motor is running on the stock in-tank EFI pump...which flows decent, and is hooked to direct battery power through a switch.....

the motor is carb'ed, no electronics, the distributor is an MSD pro billet with about 6000 miles on it, plugs are almost new, wires are new, box is an MSD 6AL...

But a better pump is not a bad idea....i am going to go through the whole fuel system anyhow....need to make some upgrades before the n20 flows......but i want the car to be in the 11's on the motor first.

im gettin aggravated with this thing because i know it has deep 11 sec potential......i may need to pay another visit to the dyno and do some more careful tuning as well

 

If I understand you correctly, you are running the stock EFI pump on a carb'ed motor?

If so, that is definitely not helping your performance. You need a fuel pump for carb'ed motors. That EFI pump is too much for a carb.

 

no such thing as too much pump, that's what regulators are for!! He might not have mentioned it in a post, but if he had the EFI pump going the car would'nt start or run worth a hoot cause all the fuel would blow past the needle and seat.

383-I assume you have a fuel pressure gauge hooked into the carb/regulator. What is your psi. preset at and does it fluctuate when you rev the motor. Not a very accurate way to see if it's running low or changing on the big end unless you have a gauge mounted mounted on the hood or the like. If your gonna feed NOS to this beast, I would recommend at least a 250gph pump and at a minimum -8AN line. Probaby should be more like -10AN feeder lines and a -8AN return line.
I sure hope yopu figure something out, I very curious to see what the aliment is. Frustrating as hell when you know it should run better than it does. We were in the same boat when we first got the truck on the track. Hopin for at least mid 10's, but the best pass to date is only a 10.72, but of course the weather has been nasty during the peak summer months, so I'm sure 10.60's are a real possibilty. I definately am gonna swap out the 750HP it's running and throw on my 950HP to see what happens. When we dynoed the motor, we took off the 750HP and threw on a 850HP and it actually lose 20hp on the top end, but moved the torque down and brought it in sooner, but peakier-is that a word? From all me experiences last season and especially this one, I'm finding out the track is about the only place to actually see what does what. I've seen dynoed motors that were"peaked out/maxed out" right off the dyno and guys played with carb or timing and found a little more on the track-go figure. Good luck hope ya find something out sooner than later.

 

dude please.....its obviously regulated down to 8 psi, i thought that went without saying....the carb would just **** fuel everyplace if it had 50psi going to it

i thought that went without saying,

in any case the fuel line is a -8AN feed, and a -6AN return.....there are 2 -6AN lines feeding the carb inlets from the regulator.....Im thinkin about goin with a fuel log though and seeing if that makes a difference, cause its very possible that the car is starving for fuel on the top end....which wouldnt show up on the dyno.

i will absolutely increase the line size for nitrous....as well as feed it with a weldon pump and regulator.

to answer your question IHI, the gauge stays pretty steady all the way through a pull on the dyno.....but at the track who knows.....i dont think its dropping much if at all....but the volume could be a consideration

 

When I was buying my braided AN line they told me the sizes are not really actual, I guess the blue hose-you know what I'm talking about that uses the push on barb fittings, is an actual I.D. measurement, so they told me that even thought the -6AN is rated at 3/8" it's actually closer to 5/16" and the same with -8AN is'nt actually 1/2", but the blue hose though ugly as sin and I'll just use it to go from the tank to just under the firewall then switch to AN line is truer to advertisement than the pretty stuff. More less food for thought I guess, but I think a log would definately not hurt at all, hell just that much more fuel storage. Life would be great if ya could just drop the $60-90 for a log and problem solved, but if your luck is like mine it will be a $2 part after you've dropped hundreds!! Actually, begore I bought this Edelbrock regulator/baseplate kit I was seriously thinking a log, just because. Depending how pretty you want, there's usually some alright deals on E-bay. Some are the real deal and others are less fancy and just used the blue hose with all the fittings, check'em out once.