I asked this same question on the TPI and Racing boards but figured Id try my luck here to see if anyone might have a new twist on things or to see what popular opinion may be. Real short my car runs 13.521 on a 1.77060ft with stock L98 w/boltons, 2k stall, some suspension and exhaust work including dual Catco cats and flowmaster cat back but it does it at a horrible 94.x MPH CONSISTANTLY. When I run it 60fts like crazy runs 8.50s in the 1/8th and then you can hear in this video Im going to post the car bog/or strain as soon as it shifts into 3rd gear and it labors the rest of the track. Normally if you spin your MPH goes up and if you dead hook the MPH goes down. Heres the funny part DEAD hooking or spinning the car runs 94.x MPH EVERY time without fail. My last Id say 15+ runs have never been out of the 94.x MPH range and Ive 60fted from 1.78-2.3 and it remains constant.
The car doesnt rev completely smoothly but this is nothing new as its idled like this for years now despite my efforts to have a perfect idle and around 1800 rpms it gets kinda choppy and then sorta smooths out but you can feel alot of vibration in the steering wheel. It has a new coil, coil wire, fuel filter, plugs, cap and rotor, and I added a Holley AFPR and set it to stock which was 48 PSI when I took the reading. The car lays down good numbers but this problem has been bothering me for some time now and figured Id run it by you guys here. SOme say it could be a failing fuel pump that cant maintain flow at those speeds and it leans out. I dont know what would only cause it to do this in 3rd gear but it happens everytime and I tried an inline harness that delays lock up in the tranny and it still does it. The car goes to the shop tomorrow cause I out of knowledge and patientce. Hopefully they can come up with something but I wont hold my breath the car has seen many a mechanic in its life to get the idle fixed and no one has come thru and now I have this new issue to contend with, any ideas??? Oh and the 13.521 run was thru manifolds, I added SLP 1 3/4s and went 13.608 at you guess it 94.x MPH, what gives?? Heres the clips....
10.6 vs 13.6

 

When I saw that movie, I thought you let up on the gas as soon as the guy passed you! Have you had the injectors cleaned (or replaced)?

 

Stock 95k mile injectors and same for fuel pump. if I did swap pumps or injectors I know I need 22# but who makes the best affordable set and I know I want Walbro but what size would I go with since its a PITA to swap out?? 190 or 255 ?? And the car does well down low, top end is non existant but 3 seconds is a heavty difference and it felt just as bad as it looked lol

Heres another from the outside that fairs a little better =)
13.92 Run

 

I don't have my GM book handy; but they do give a flow test for the fuel pump... maybe someone can type it up for you? Also, how's the distributor? Has it been rebuilt lately?

 

Distrib was shot about 4 years back, all corroded to hell so it was replaced but I had to use a Pep Boys piece to get it going since I didnt have time to order thru Summit. Even back then the new one didnt help the idle any but I didnt have the bogging problems back then I do now. Ive had a new coil, module and pick up replaced in the new distrib since I installed it some 4 years ago. Currently its at a shop to see if they can find out whats up. If they cant find anything Im just gonna leave it alone til the L98 quits which is what Ive been waiting for but Ill be damned if at closing in on 100k miles and 100 trips at the track and it bends but never breaks.....

 

Are you over-reving it between 2nd and 3rd causing lifter pump up?
This would kill third gear power. Try making a power run in third gear only, to see if it breaks down then.
If it's a lifter pump up problem it won't show up then, if its
ignition or fuel related it will show up again.
Another posibility is over advanced ignition timing.
Your motor may not want or need as much timing while under
the constant load of third gear acceleration. (it is more thermally efficient.) Many race cars employ high gear ignition retard to
get around this. Try retarding your timing 2-3 degrees.
ET may suffer but if the mph improves, you know what to do.
Consider using a cooler heat range spark plug (for the same reasons) hope this helps.

 

The car runs stock timing so I dont think thats part of the problem here. As far as over reving it the car shifts itself I never do it manually and the car pulls to 5100 rpms and shifts just fine and I never leave it in OD at the track. Ive tried from a rolling start in Drive and it downshifts and as soon as it shifts back into Drive is when it always occurs. If the car doesnt downshift I dont know if it does it still but I guess I can check that out easy enough but for some reason I still think its hits the 4k RPM wall and just labors ever so slow, thanks for the info tho Ill see what I can do....