I was wanting to know what kind of a 1/4 mile time I am looking at if my trap speed is 94 Mph. I have messed with one of those 1/4 mile calculator and it says about 14.4-14.5 I thought that I would just rely on my fellow third geners.

Thanks,

Brian

 

thatz approximately correct, but it veries based on ur short time or 60ft. time as some call it, when i first got my car it consistanty ran 15.0's @ 92mph, my best time in the IROC was a 14.8 @ 94 mph, however my 60ft. time was a 2.01 which is extremely well, most cars that run mid 13's have short times this good, usually a car running my elapsed time would run a 2.1 or 2.2 instead of my 2.01.. i got to the track with a 99 Formula which has run a best of 13.48 @ 108 with a 60ft. time of 2.00.. so u can see how there are differences.. i've seen IROC's run like 14.0's @ 99 mph, and i've seen them run 14.0's @95 mph, it all depends oh how ur car runs and pulls down the track.. as for my car it has a bad mid-range curve, it runs very fast out of the hole (2.01) and it has a very high mph at the end of the track (94mph) other cars i've seen @94mph run about 14.5's.. so basically my cars off a bit, but all in all generally u can use that 14.4-14.5 @94mph as a guidline, i'm just telling u the variables which could change ur time.. who knows u might run a 13.5 @94 if ur car screams out of the hole and dies on the top end haha.. good luck. mike

 

Thanks Mike. I want to get down to the track but it seems that there is something that always comes up when they let normal schmo's run there cars. I was running at about 90mph then I replaced the radiator and it helped my mid end alot.

 

To find out how to realy get the most out of your car in the 1/4mi, get a copy of Drag2000 from Motion Software, Inc. for about $50.

Once you have it set up to produce current time slip results you can vary launch and shift points, among other parameters to optomize track performance.

 

MPH is mainly reflective of how much power you have
ET is reflective of how effectively you use that power.

An old racer's rule of thumb for everybody...

Take your ET and multiply by your trap speed. On an ideal drag car this number would be 1320. Higher means you're not using all your power to get down the track.

For example, stock i ran 15.2 @ 90 = 1368
Now i'm running 14.3 @ 95.2 = 1361

So i'm actually more effectively using my power than when i was stock, which makes sense with the gears and much smaller low end bog that i'm getting.

Just a neat trick that you can use to get an idea of how well people's cars are working. Go ahead and try it with the performace of people you know and you'll be surprised at how well it works.

 

holy crap, that means i have alot more power in there, where's it going?? do u know of a way to correct this??

14.8@94 = 1391

my launch was great though, 2.01

i wanna go faster!! should my upgraded suspenion fix this problem (lower control arms, sub-frames, strut tower brace, pan hard) i haven't taken it to the track yet to find out.. how can i get this power back?? if i had a perfect 1320 my 305 would be really smokin' with just bolt on's.. i have all these mods done to it so i guess i should wait to see what the new times r, i know i'll be in the 13.9-14.0 range though cuz i race my buddies stock LT1's and i can beat them by 2 car legths and they run 14.1's at the track.. help me please !!

 

By MY numbers my car has all but tapped what it has to give and then some. 13.521 @ 94.4 = 1276 Im wondering if this is any reason why adding headers didnt do a damn thing for me, but I KNOW it has some issues that need to be ironed out, I just need to get some $ to throw at it...

 

That's very good short time on streets. You'll find that the SFCs will realy help you hook up; the pan-hards will help a little. I have the SSMs on the IROC; they bolt/weld to the rear sub-frame, weld to the front sub-frame and tach weld along the inside of the rocker pannels. They weigh 15lbs each and realy stiffen up the frame. You can lose the spare and jack to compensate for the weight (40lbs=.5mph=.05sec).

You may (likely will) find that you need a higher stall TC and DRs to get to the optimun ET, based on trap speed (=HP). It's not that the power is hidden, it's mostly that you're not launching high enough in the power band, but then you will need DRs to put it to the pavement.

I'll have to apply that ET * TS = 1320 equatioin to some of the Raceway Park guys time slips. Several are set up for optimun ETs.

 

I race at Etown as well and my times came on BFG drag radials and a 2k stall, shift kit and cooler and I already have the SFCs, LCAs, PHB, and STB and Im already minus the jack and spare and the rest is stock except the usual bolt ons and I actually ran better thru manifolds so far. Next up AFPR, complete aftermarket intake, new injectors(only part not already paid for) and then some fine tuning and I have a guy thats gonna burn a prom for me. Ill be up there SLP day so hopefully Ill get to see some members from the boards there...

 

I'm not sure exactly how / who that rule of thumb was derived, but it's definitely interesting. What i find interesting, is even if you give it a top fuel et/mph, like 4.5 @ 300 =1350. It must be the result of some tinkering with HP, and work functions. I wonder if 1320 is the true ideal number or not.

Thirdgen92, in your case of being so far ahead of the 'ideal' case i think it shows that you have a real problem. In that you are definitely getting great ET like you have good power, but then you fall on your face. I'm still betting it's a TCC issue, or knock retard or something. I mean it was plain as day in that video so you'll probably know when you fix it.

SnkSknr, yours doens't really make sense since you seem to be hooking w/ that 60'. Are you getting alot of spin on upshifts from a shift klit or something? Anything strange at all happening at the top of first gear into second. Something is bringing your ET down but still letting you get a good mph, so it's most likely affecting you somewhere on the bottom of the track. Do you have 330, 1/8 and 1000' times too, they can help figure out where you're laying down.

 

Sorry, my bad, I was refering to SnkSknrZ28.

True, ThirdGenZ28 92, you are ahead of the curve. If the equation is true your trap speed should be about 97.6mph. Maybe some work with a scan tool will find the problem.

Here are two equations I use to estimate crank hp from trap speed:
HP = (mph / 234)^3 * weight
ET = 85.75 * 15.822 / mph = 1357 / mph
I don't remember where these came from but you can see that the latter disagrees by about 3% with the ET = 1320/mph.

I just did some optomization in Drag2000 (3,400 TC & slicks) and the "best pass" for my Vette is predicted to be 12.32sec at 107mph. This gives a 1318 product, so looks like 1320 may be a good rule of thumb for the ET * mph product.

 

Im working on it slowly but surely, as soon as I find out whats wrong Ill post about it. Scan tool showed 2 degrees of KR when I advance my timing so I returned it to stock, I replaced a corroded coil and coil wire and Ill have an AFPR in place and new wires on and Im gonna try the torque converter lock up plug in harness, my next day at the track will be the 20th. I hope I find SOMETHING out, I just wish I had more knowledge or knew someone who did locally that could lend a hand...

 

I'll bet the reason you lost power with headers is you didn't have an AFPR to trim fuel flow.

Record the current fuel pressure with the vac line disconnected so you have a baseline. Consider an ACCCEL gauge from Jegg's. It fits on the fuel rail of an L98 or LB9 and is very handy for checking pressure and leakdown.

Good luck at the strip. Maybe I'll see you at Raceway Park sometime, if I ever gett the Vette back on the road.

 

hmm 1429.... I guess I could stand to use my power a bit more efficently.

1320 happens to be the number of feet in 1/4 mile...

Coincidence ?

 

I have a Holley AFPR Im gonna slap on this Sat weather permitting and a non AC heater box to free up some room. I talked with SLP and they said the same thing that I might be leaning out and an AFPR might help and I have the hand held fuel pressure gauge but I have a Nordskog digital fuel pressure guage and sender, I just need 4AN line I think it is with female ends so I can keep an eye on the pressure at the end of the 1/4 where I tend to have problems, car bogs right after it goes into 3rd gear....

 

It's possible. Especially if you were getting into knock w/ just a little extra advance added in, the stock L98 spark curve is kinda low, like in the low 20s total w/ stock initial)

If you're tracking knock counts you must have a scan tool of some nature. I don't know if we went through this before, but what are your O2s doing? Even though O2s are useless to tune by, in this situation it's definitely better than nothing. If your O2s are way low (like near 800mV or worse) then you're definitely lean. If they're high way over 900mV then you're probably rich

 

924 mV which I understand to be a little fat but not too bad and not anywheres near the lean condition I was expecting. Im still eyeing new injectors like one guy who looked at the car suggested when I swap the new intake on, I just need to find a good replacement for my set of injectors either SVO or Accels but I dont know what # or which ones would benefit me since neither are rated at exactly 22#s...

 

ThirdGenZ28 92, though our O2s are in the outer limits at WOT, mine was reading 920-940mV at WOT and dyno pulls the same day showed 12.6-12.8 as the ai/ fuel ratio, which was pretty good.

You might pick up a set of used Vette 22# injectors and have Rich at Cruzin Performance recondition and blue print em. I got a set for my IROC for $100; after Rich reconditioned them for $80 they flowed to within 1%.

Before you go to bigger injectors check out the table on my site that shows flow & hp supported vs fuel pressure for several injector sizes. You don't want to go too large till the air flow is there.

 

SnkSknr, yours doens't really make sense since you seem to be hooking w/ that 60'. Are you getting alot of spin on upshifts from a shift klit or something? Anything strange at all happening at the top of first gear into second. Something is bringing your ET down but still letting you get a good mph, so it's most likely affecting you somewhere on the bottom of the track. Do you have 330, 1/8 and 1000' times too, they can help figure out where you're laying down.

i think my shift are good, from the 1-2 shift usually the tires bark, and on the 2-3 shift sometimes it is just a solid shift, and other times it will bark them slightly but not as loud as the 1-2 shift and after each shift it give a good hard pull, it doesn't seem to lag whatsoever.. my car shifts at approx 4800-4900 rpm but i think that is normal for 700r4's, could it possibly be slighty out of the HP range where i would lose some power, sometimes it seems like its screaming before it shifts but other times it sounds good, i guess u'd have to be in the car with me but it always shifts at 48-4900rpm.. off the top of my head i believe the 1/8th mile time was in the range of a 9.58 @72mph.. don't recall the 330 or 1000 #'s, i'd have to pull out the ticket.. these times are also without any of my mods too, this was all stock, i havn't been to the track with the car since the mods yet, i did them all during this past winter.. pretty quick for a LB9 with a A4, 3.23 gears, almost unrealistic i've been told but i have the timeslips to prove it, my friends still tell me its gotta be a slow 350 or somthing cuz they've never seen a stock 305 post those numbers.. so any suggestions as to why my times r screwed up?? i'd like to fix it if possible and see what she'll really do..

 

any ideas guyz ^

 

Sorry man, there's just not much else we can say i guess. You are definitely losing your ET somwhere on the small end of the track. We can't guess exactly what is causing it though w/o driving your car. You must be getting some kind of bog, or excessive wheelspin on teh upshift, or maybe even heavy knock on the shift thats taking your timing away briefly.
I wish i could offer more, but there isn't much else obvious that could be causing i.

 

well that sux, people already don't believe my times and according to that little rule thumb thing i should be faster even?? wierd.. talk about a freak 305.. well i'll play around with my new line of mods and i'll post something in here later on and maybe we can debate a bit on it.. thanx

 

My s10 blazer runs 14.8@92 2.1 60ft. with a 305tpi. I have replaced the peanut cam with a l98 cam and thats it. I dont think you have a freak 305. My blazer weighs 3900lbs and has 3.23 gears.

 

Hehehe, sorry SnkSknr your car isn't even as 'freak' as mine. I guess you missed that i ran 14.3 @ 95 with a similarly stock combo as yours. Only difference is i bet my fully loaded vert has a couple hundred pounds on you.
Don't let haters get you down. As you can imagine i get people trying to call my car a freak too. I just figure they're just jealous that they can't get their car to put up the numbers. If they don't want to believe you have a 305, thats their problem, not yours. What happens down the road when you do start pulling some secrets on them?

 

Actually, in top fuel it would be more like 4.5*330=14.85. Funny Car would be about 4.75*326=1548.5. Pro Stock would be 6.8*203=1380.4

 

Damn. I just noticed when I had my 305 in it would be 16.11*82=1321. Hmmmmmmmmmmm Thats real interesting.

 

no kidding!! thatz awesome.. what track did u race at, maybe the air density was on ur side to pull a time off like that, or maybe u gotta 350 lol, j/k, thats what everyone always tells me.. oh well.. ya usually its the people that are in denial after i beat them in a race and they have like a new Gt or an LT1, they dont like hearing i only have a bolt on 305.. who knows though if i were running a 14.3 or 14.4 ET along with my 94 mph time maybe my car would be more in its range.. i just gotta find out whatz going on with it.. i had a feelign before i had the AFPR the my motor was starving top end, when i turned that up i noticed much more of a pull.. when i would get on it, it seemed to pull hard up to about 65 mph and then it seemed to drag on a bit like it was pulling but only half assed, after the regulator i've had the thing pulling harder than before and all the way up past 100 (i didn't wanna go any faster than that, too many cops around)..

 

SnkSknrZ28, that's indeed very good trap speed; I had to struggle (with the '86 "peanut" cam) to break below 15s.

Since you have a pretty strong A4 you might consider a TransGo shift kit; you may be loosing a little ET on the shifts.

Lets see what numbers you turn with the mods.

 

crap, ya i really gotta get to the track bad.. it might be a couple weeks still though cuz i race my dads race car and they have Test and Tunes the next two saturdays, then racing starts, so ill have to take my IROC to a Test and Tune if i have time to even play with it but it might have to wait until racing starts cuz i have to practice in the race car for the next couple weeks :-( i realy hope i see some big improvements in my car though cuz i did all the mods im my sig this winter and its kinda hard to feel if its faster or not, its so hard to tell without going to the track and seeing the times, i think i feel a harder pull, some of my friends say its feels alot faster, and other say they can't tell either.. r the B&M Shift kits no good?? i really dont know, well this fall i'm getting this tranny rebuilt for the new motor so maybe i'll have them put in a new shift kit.. any guesses what i'll run?? when i bought my car it had a Hypertech chip and stat in it and i ran a 14.8@94, what do u think i'll see with this round of mods in my sig?? please don't say 14.7... haha..