ok. car runs 8.55 at 80-81 mph in the 1/8 mile but posts a lousy 13.5xx at 94 mph in the 1/4 what could possibly be holding my last 1/8 mile back? gaining only 14 mph in the last 1/8 mile is killing me.

I think you are pretty close to what you are supposed to be.

can you post your timeslip, that might help a little more, for instance the 60 foot time, 1000 foot time etc

will post slip tonight. at work now. slips in car at home

Need details on your combo. Sounds like your mph is way down, which would be caused by lack of top end hp.

8.55 = 13.3 in the 1/4 so you're not too far off. Many factors can affect the last 1/8 mile.

I'm not going to retype everything so just go and read this page. It may help some.

http://www.hardtail.com/techtips/analizingtimeslip.html

13.5x's at 94ish is a little odd....what's timing and fueling look like?

94 is definetly low for a 13.5 pass seems like it pulls well to about 1000' then falls off. verify your fuel pressure is steady or it might be your third gear slippin

it could be a multitude of things, but fuel supply and timing tables are definitely where i'd start...

ok sorry at work again motherboard on home pc went POOF
this on m/t i tread street tires size L60 x 15 taller tire than stock by alot
60' 1.854
330' 5.488
1/8th 8.566 @ 79.33
1000' 11.265
1/4 13.571 @ 93.04

fuel pressure digi gauge holds 52 psi @wot for the entire pass walbro 255 lph pump afpr set for 52 @ wot.

guess i have to play with timing some maybe

52psi? is the car tuned at that pressure or is it just stock stuff? or is it an LS1 swap....

that would put you pig rich unless the car was tuned at that pressure.

my combo
intake sytem- slp cold air, gutted maf, twin 52mm TB, ported and siamesed plenum, AS&M semi siamesed runners, tpis big mouth manifold.

fuel 255lph walbro pump lt1 injectors again @52 wot pressure.

longtubes duals with h-pipe and a set of moroso spiral core mufflers.

isky cam and 1.6 rollers. cam roughly 480/480

What are the specs of the rest of the cam?

cam specs.
valve lift int/exh 465/465
adv duration 270/270
.050 duration 221/221
lobe center 108

i figured roughly 480 int and exh due to 1.6 rockers

i think i may have stumbled on to something. could be wrong though; i up'ed my tire size from a 26 to a 28 inch tire. from what i can find in some searching this would change my rear gear from a 3.27 to roughly a 3.02.

gonna run with the 26 next and see if there's a difference.
if so i think i need more gear.

108 lsa with a tpi style intake? anyone else see this as kinda mismatched?

60ft isn't bad and 1/8 mile is ...okay.... but the MPH goes to crap somewhere during the run. Is the trans fresh? Could it be slipping in high gear? What stall converter do you run?

Any chance your trans is holding second gear too long?

trans TSI racing. 1 year on it.
2600 stall
custom weighted governor in trans done by me, comes outa 1st at 5400 rpm shifts from 2nd to 3rd at 5300 rpm.
any higher and i run into the famous tpi flatline

I'm not a TPI expert but.......this doesn't sound right. What happens if you manually shift the car at 6000-6200 or so?

I never owned a T.P.I. motor before but I thought the wall was closer to 4800
rpm.You could try shifting earlier and see if it helps?

you should be shifting at 5700 roughly with your combo. 5400 seems really low

nah car flatlines at 5500 rpm no more pull kinda like releaseing a parachute.

yes 84zeddd stock tpi systems hit the infamous wall at 4800-4900 rpm

with my modified intake i pull hard to roughly 5400-5500 rpm

if it were a modified lt1 i could probably pull to 6000 but not with tpi

gonna check 1/4 mile trap rpm next visit to track

yeah my car hp flatlines at 5700 to 6300, and I shift at 6200

never tried it. would need to change valvebody at this point in order to make that happen

I don’t see the great big mystery… your ET is close to what it should be, you stuck L60’s on the car that are typically in the 28-29” tall range and you’re running 93mph (probably crossing the line 94-95mph)… that combination is causing you to shift right before the finish line so you’re going to show the worst time you could possibly show with that combination. Get it to cross the finish line >1500rpm higher and your numbers should end up in the mid/low 13’s at just around 100mph.