fast.asleep said:
I've been told by a "performance" shop that headers on a stock L98 motor will make absolutely no difference. (The guy also told me that retrofitting a LT1 intake to a TPI motor is impossible) :eyerole
Take a look at Mad-Mic's car domain page.. He put headers on a stock '87
i was gonna say.......lol
but anyway with a few mods
K&N open air box, MAF descreened, TB Bypassed, 160* T-Stat, Accel Super Coil, 12* degree advance timing, TPiS Long Tube Headers, airfoil, !EGR, and dumps off the rear Y pipe. Hayden Tranny cooler. Stock 1600 rpm stall, 2.59 rear gear on 275/40/17" BF Goodrich Drag Radials.
the car made 40 more hp and 58 lbs of torque at the fly wheel if you go by a 17% loss but i believe with the 4 additional u-joints its more like 20% which would be 47 HP and 69 toque at the flywheel. this was on only 1 pull due to a blown EGR connection on #8 cylinder and over 220 degrees water temp. with these problems the car still pulled the 235 rwhp and 345 lbs of torque. i'm sure the car could of pulled atleast 20-25+ more hp and torque if the car was cooled down and the egr connection didn't blow and lose all back pressure on #8 cylinder. i think thats a conservative guess due to loosing .2 at the track between cool 140-160 water temp and anything above the 180 range thats what i lose when i've hot lapped the car numerous times.
with these same mods with out the headers and with a catless front Y pipe, the car ran a best of 13.26 @ 103 mph with a 1.83 60' time. best 60' with out the headers was a 1.81 on street tires. this setup was maxed out as far as i'm concerned so there is potential to run some pretty good numbers with just some basic mods with out sinking money into headers. with true duels you might see another tenth or 2 with out headers. the primaries on the stock manifolds is 1 1/8". on my TPiS it's 1 3/4".
Big difference when it comes to making HP.
haven't had alot of track time to back up the header install and a few more additional mods like DR's, crank pulley, air elim pulley, and cut back plugs but with just the headers alone i picked up close to 3 mph at 1000' more DA. this would equate to another mph if i was at the same DA i ran the 13.26 with out the headers if every 1000' of DA is .1 and 1 mph which = 10 rwhp on 12.0 and slower cars.
will be dynoing the car again soon to get some better #'s but as you can see a good free flow exhaust can pick up a good bit. 3 mph is = to 30 rwhp from the headers only. i seen many dyno runs from LS1 cars and headers alone average 22 rwhp so this is pretty consistant from what i hear about L98's
then leave them off altogether.
