Allright this is driving me crazy about 2 months ago I bought a Used 96 Z28 with an A4 I took it to the track the first week I owned it best run was a 14.5 at 95 mph with a 2.11 60 ft time with a .542 RT that seems pretty low for what is on it there is JBA headers, Flowmaster exhaust.. Smaller pulleys Camaro SS intake and hood.... Now originally I had done nothing to it well the air filter was clogged with leaves and the fuel pressure was running nearly 60 psi at WOT... So I put an adjustable fuel regulator on it adjusted it to 47 psi changed the air filter to a new K&N I had sythentic gear oil put in the rear end had a compression check done that came out good and even had a remanufactured performance transmission and a 2000 stall torque convertor put in as the old one crapped out on me a couple of weeks ago..... Well tonite I ran the car for the first time since all of this went in and the best I could get was a 14.5 at 96??? WTF.... Im out of ideas about what is coming up short.... could it possibly be something in the ignition the plugs and wires are about the only things I havent checked... Any Ideas???

 

What is the elevation at the track you run?

How many miles are on the car, it might need freshened up a bit.

There are lots of factors, but basically a good running A4 should run low 14's if not high 13's, especially with those mods.

-Dustin-

 

fuel pressure too high?? were you spinning more off the line??? did you pack on like 200 lbs in that time period?? just tossin idea's here on a side note dont feel too bad i have a buddy with a full bolt on LS1 and his best time to date is a 12.99.

 

It can be many things. Clogged cat for one. Also, even though you put an adjustable fuel regulator on, our computers will eventually compensate for them and bump the pressure back up to 60psi (or max out the fuel pump's flowing capacity=bad). You should probably get a tune from pcmforless or the other guy on the board (srry i can't remember the name cause it's 5am) and have them set the factory fuel pressure in the tune. That mph does seem really low, even for a stock z28. Then again my friend's who has exactly what I have except he has shorty headers while I have mid-length, he runs a 13.8@99 to my 13.3@104. Good luck.

 

Yea hopefully its just needs too get tuned.... I can't really think of too much that hasnt been checked out... Oh yea I was running at sea level in Florida

Thanks guys for giving me some ideas

 

get a cutout before that flowmaster, 160 T-Stat, get a tune, and throw a lt4 knock module in there if your slipping off the line, pop some drag radials on there. If your times dont drop. I would look into replacing that opti'. MPH seems low, unless your stuck with the dreaded and horrible 2.73's.


Oh and did they add a trans cooler with the new rebuild too? If not, add one ASAP.

mike

 

Buying a car and taking it to the track right away? Your times-albeit quite respectable in my opinion, will probably be the least of problems.

 

I ran best of 14.3 at 96mph with a 2.18 60ft this season.I have a heavy,race weight 3825 with me in it z28 vert.For mods at the time had magnaflo catback,airfoil.g2 air induction,holley filter,160 stat,slp fan switch,hpp ..tuning out,maf translator,tb bypass,1le bellows.And 3.42 gears.Car is auto.
Previous time at track was running with 2.40 60fts on street tires had nittos the last time the car ran 15.0 at 94mph .This time with a 2.40 60ft it still ran like a 14.5 or so.
So it seems the gears and catback were worth three or four tenths.
Car came with 2.73 gears.I also thought my mph was low but am at 1900 feet above sea level and had high headwind the last time I raced.Buddies similarly modded 94 non vert only makes around 99 at our track.He has 3.23 gears,flomaster catback,1le bellows,airfoil,similar cold air system He has got a best of 13.8 or so on drag tires.
I am wondering if my opti is part of the problem as did lose a water pump and did get a lot of water on my opti.Will likley go to delteq or something similar in spring.Also weird is my car has run around 98 mph before and after the track runs.This was on my tazzo vpc which was track tested to be 2.5 mph high and got like 100.5 on it so thats where I get the 98mph corrected to track mph.
Maybe it was wind and maybe bad opti or wires or plugs haven't changed any of that out.
I have bought 1.6 rockers and asp underdrive balancer and hoping that gets me into the 13s at our track.
Track altitude makes a big difference as does weight.Buddies car is like two or three hundred pounds lighter than mine and that seems to show the mph difference since our mods were bascially same.And even the ls1 usually only go around 102 at our track stock.

 

I think you as well need to get a good tune done through madz28.com or someone else. I would also look into the subframe connecters, especially since yours is a vert. Getting that power to ground efficently is they key to kicking *** at the track. You can pretty much say, for every .1 you drop off your 60ft time, its worth about .2 off your 1/4 mile e.t. Im sure many can vouch for that. And that is why you see guys with 2800 or bigger stalls with sticky tires cutting 1.7 or better 60ft times, with much better et's then the guys without them.

Mike

 

I have bmr subframe connectors..not impressed with them usually only use kenny brown double diamonds on my ls1 and previous lt1 cars.I might even cut off the bmr and put on kenny browns on the vert.

I should have been able to get a 2.0 or so with those nitto drags I had on that last track day.I didn't bother heating them up properly and track was very slick that day from all the full bore race cars.I have since sold the nittos but might get another pair.They were used and flat spotted badly and hated them on the highway.They were very noisy.Guy had them on his car for like 1 and half years and didn't move the car.

I also was going to say that 2000 stall is so close to stock I think that doubt it will do much if anything in there.I plan on 2800 to maybe 3000 vig in my car also this season depending on money and likely getting a set of the new et street radials to play with at the track.Course I run the risk of being kicked off at 13.5 I believe with the new nhra rules.I am going to be telling them my car is stock for as long as I can though New stock rules are way faster even for verts..
Unless you have nitrous or a super lopey cam can't see how they can tell.Not sure if headers are allowed in pure stock either.So my track days are numbered in my vert.No plans for a cage in that car.Athough guess never say never.