LS2 Chevelle: ported 799, 230/238 cam, Fast 90mm results
10-18-2015, 12:41 PM
#1
LS2 Chevelle: ported 799, 230/238 cam, Fast 90mm results Finally got the car to the track on a good tire. The Hoosier 275/50r17 DR2 drag radial is by far the best tire I have ever used.
Car:
~3700lbs raceweight with me in it
71 Chevelle
LS2 shortblock
locally ported 799 heads, milled .015", stock valves
Cam Motion 230/238 113+3 cam (ls7 lifters, stock rockers, 7.4 pushrods, Brian Tooley springs)
Fast 90mm with mild porting to remove wedges
85mm maf with straightener in a 90* rubber elbow with a gigantic cone filter with a velocity cone in it
Doug's swap headers 1 3/4" with 3" collectors into 3" duals with dual cutouts
Powerbond underdrive pulley (20-25% I don't recall)
Built 4l60e
Yank SS3600
3.5' chromoly steel driveshaft
12 bolt 3.42 gear
275/50 Hoosier radial
dyno sheet unlocked with cutouts closed, 418rwhp
DA was hovering between 670-770 ft all day
first pass: 12psi tires (low because I was in a rush to qualify), 6700 1-2 shift 6500 2-3, cutouts closed
second pass: 18psi tires, 6500 1-2, 6400 2-3, cutout open, rich 11.8-12.2 afr reading in 3rd
third pass: 18psi, 6500 1-2, 6400 2-3, cutouts open, leaned out and it read 13.0-13.2 afr and picked up 1.1 KR on launch and left it out for most of the pass
fourth pass: 18psi, 6500 1-2, 6400 2-3, cutouts open, added 2% fuel back in for ~12.8 afr, splashed in some 116 to prevent KR, lined up in the groove where street tire cars had stripped all the rubber so it spun
fifth pass: dropped another 100rpm off shifts, lined up outside the groove
6th pass: same tune as above but got wheel hop
7th pass: same tune as above but hooked again
Previous best with LS1, same heads but less porting, EPS 230/238 113+2, dynoed 389rwhp on the same dyno, on MT ET Street 275/50, nearly the same DA
1.72 60ft
7.45@94mph 1/8th
11.67@115mph 1/4
I think that the cam peaking so early is hurting my times. The car felt like it was pulling all the way through, but right after it shifts (most notably to 3rd) it jerks forward and really starts pulling. It's insane how much low end it has on the street but it seems to be leaving a good bit on the table at the big end of the track. Obviously the extra torque is greatly helping the 60ft over the LS1 setup as it dropped a full tenth.
I don't understand how on some passes the car could 60ft harder, pick up MPH, but still run nearly the same ET.
Car:
~3700lbs raceweight with me in it
71 Chevelle
LS2 shortblock
locally ported 799 heads, milled .015", stock valves
Cam Motion 230/238 113+3 cam (ls7 lifters, stock rockers, 7.4 pushrods, Brian Tooley springs)
Fast 90mm with mild porting to remove wedges
85mm maf with straightener in a 90* rubber elbow with a gigantic cone filter with a velocity cone in it
Doug's swap headers 1 3/4" with 3" collectors into 3" duals with dual cutouts
Powerbond underdrive pulley (20-25% I don't recall)
Built 4l60e
Yank SS3600
3.5' chromoly steel driveshaft
12 bolt 3.42 gear
275/50 Hoosier radial
dyno sheet unlocked with cutouts closed, 418rwhp
DA was hovering between 670-770 ft all day
first pass: 12psi tires (low because I was in a rush to qualify), 6700 1-2 shift 6500 2-3, cutouts closed
second pass: 18psi tires, 6500 1-2, 6400 2-3, cutout open, rich 11.8-12.2 afr reading in 3rd
third pass: 18psi, 6500 1-2, 6400 2-3, cutouts open, leaned out and it read 13.0-13.2 afr and picked up 1.1 KR on launch and left it out for most of the pass
fourth pass: 18psi, 6500 1-2, 6400 2-3, cutouts open, added 2% fuel back in for ~12.8 afr, splashed in some 116 to prevent KR, lined up in the groove where street tire cars had stripped all the rubber so it spun
fifth pass: dropped another 100rpm off shifts, lined up outside the groove
6th pass: same tune as above but got wheel hop
7th pass: same tune as above but hooked again
Previous best with LS1, same heads but less porting, EPS 230/238 113+2, dynoed 389rwhp on the same dyno, on MT ET Street 275/50, nearly the same DA
1.72 60ft
7.45@94mph 1/8th
11.67@115mph 1/4
I think that the cam peaking so early is hurting my times. The car felt like it was pulling all the way through, but right after it shifts (most notably to 3rd) it jerks forward and really starts pulling. It's insane how much low end it has on the street but it seems to be leaving a good bit on the table at the big end of the track. Obviously the extra torque is greatly helping the 60ft over the LS1 setup as it dropped a full tenth.
I don't understand how on some passes the car could 60ft harder, pick up MPH, but still run nearly the same ET.
10-18-2015, 02:32 PM
#3
Yes, I did both.
I do think there was a tailwind the day of my old best but I wouldn't think it would account for very much.
Looking over the logs again I think it is still a tad too lean in the really high RPM, but again probably not enough to make a massive difference.
I was really hoping to be trapping 118mph or so.
I do think there was a tailwind the day of my old best but I wouldn't think it would account for very much.
Looking over the logs again I think it is still a tad too lean in the really high RPM, but again probably not enough to make a massive difference.
I was really hoping to be trapping 118mph or so.
10-19-2015, 08:10 AM
#6
It might have picked up a little more if I dropped the shift points down again I suppose. The 2-3 happens late after commanded so I probably should have tried 6200 and 6000 for shift points.
The car feels stout as hell on the street and I've taken it to 7000rpm before and it felt like it was pulling.
One thing I did notice was right after the passes I was hearing some noise but couldn't pin point if it was in the engine or under the car. Kinda sounded like a metallic tapping. Wondering if my lifters might have been bleeding off...not that there is any reason they should have been.
The car feels stout as hell on the street and I've taken it to 7000rpm before and it felt like it was pulling.
One thing I did notice was right after the passes I was hearing some noise but couldn't pin point if it was in the engine or under the car. Kinda sounded like a metallic tapping. Wondering if my lifters might have been bleeding off...not that there is any reason they should have been.