Ok so last time i was at the track, i had all the mods listed in my sig, with the diablo tune on and timing advanced all the way, minus the 75mm TB/Plenum. Ran a 9.07.

Put the TB and Plenum on a couple weeks ago, didnt change anything else, and yesterday i ran a 9.37.... 9.37!?!? Other times were around the 9.4 range... WTF... Car felt kinda slow off the line and my 60's were in the 2.1-2.2 range. But it felt like i was getting more power top end... as the race was ending...

Friend of mine suggested removing the tune altogether, but by doing that, id be turning the timing down again which would lose power wouldnt it?
Ideas? Think I need an actual dynotune?

 

The tb/plenum isnt going to do much in the 1/8th, mostly top end gain if any at all.

It was probably the variation in track temp, ambient air temp, humidity, pressure etc that affected the DA and made it run different.

Tires also perform worse and worse as they wear (of course) but even tires that arent totally worn can run a lil worse than new ones.

 

Tires shouldnt be an issue, i was getting traction just fine. And it was a nice day for the track, wasnt too hot out, mid 70's, sunny so the track surface was nice and hot, and there was a slight breeze too.

 

with a 2.2 60' how much traction could you be getting?

its always best to get a re-tune when you change the breathing of a motor. otherwise the extra air cannot be fully utilized.

 

^+1 Gotta question your traction with a 2.2 60 foot. Did you post similar 60 foot times when you ran the 9.07?

 

Post up BOTH Time Slips completely.

 

You dont need a retune for a TB/plenum.

A tune will always get some more out of it, but those are pretty minor mods that dont do much either way so it doesnt NEED a retune.

I run stock tune with what i have, and run 8.6's, another dude here runs TB/plenum, pullies, longtubes, full exhast, etc and runs 8.3's or 8.20s on stock tune.

 

Do you think a dyno tune would make all the cars mentioned faster?

And the "dude" you mention. Does he run with slicks?

 

i had a 1.9 60' when i ran the 9.07, and ill take pics of the timeslips when i get home tonight.

Im getting good traction and all, but it just feels like i dont have a lot of power off the line, tried launching at idle, 1500, and 2300 (squealed a bit off the line), had pretty much the same results (9.4). Tires were at 20psi.

 

Agreed. You don't 'need' the tune, but as already stated, just increasing your flow is not going to give you much help down low unless you account for the air and adjust your timing in the tune.

IMO, before even worrying about air flow on your car, I would be looking into getting my 60's lower. Especially, in the 1/8 mile, the first 100' is everything.