fastest not-running to 10 second volvo build ever.
Drop tire pressure? It black tracked for quite a ways downtrack.
Screen door shocks for the front?
Needs a narrow rear axle and tubs so you can get rid of the stink bug attitude and transfer more weight.
Lean out launch, it stumbled bad. Would it be better strategy to have the AFR's right and control power with timing on the launch?
Trans brake?
3.54 Rear gear seems high for the tall tire. What was trap RPM?
Are you data logging runs?
That's a lot to unpack (and some of it was addressed above) lol
It didn't spin off the line, that last pass was as much a case of the track going away as it was anything... the previous 3 runs were absolutely uneventful.
Launch was waaay rich, didn't get much time to play with everything as it was a shakedown day, not a max effort day. Several things stopped working since the last time the car went to the track.. most notably several switches on the dash that control things like launch control. So... it didn't hit hard off the line at all. No trans brake. not going to worry about that right now, would really like a forward pattern brake because I really like my shifter, but something is probably gonna have to give in that department at some point.
gear ratio is about right for the target, just not for the current state of affairs. 129mph trap speed, going through the traps at 6800 or so. When it was trapping 142 on the previous setup, it was up in the 7's, so there is that.
link to the post with the rough engine specs:
http://forums.turbobricks.com/showpost.php?p=6011174&postcount=3079
trans is as before, th400 with looped gov pressure (i.e. full pressure all the time), modified booster valve and higher line pressure spring (tci spring). it's nothing crazy, basically stock with select modifications done as per the article on nastyz28/crankshaft coalition wiki.. dual feed mod, 4L80 drum and sprag, I think it's running a 6 6 and 4 clutch count.
to launch it, I load it up in 3rd where I can lean on the converter without really working the brakes too hard, and hitting the launch button (previously the brake switch, currently the button on the shifter.. I have a tendency to not let go of that though, so we'll be putting it back on the brake switch after I replace the inline kill switch), and when the desired criteria are met, drop to 1 and let fly. This has the added benefit of pre-loading everything ahead of time vs the ever destructive neutral-bomb that one seems to get from a trans brake or manual transmission launch with a tight clutch.
I will probably make the jump to an 8.8 in the wagon (well, both of them), and at that point I'll start looking harder at a transbrake, and depending on where I am with engine development, a switch to a glide. Maybe not though, kinda all depends. The th400 is likely going to need some love in the long run (nothing terribly serious, but costly enough to consider a couple of options.. I rather like it TBH) if the rpm range is going to keep climbing up.. as it sits now I may play with it on the rollers to see where I really should set the rev limit, it wasn't dropping off hard at 8100, and if I can run it a little higher at the track, it may run out a little better up top.
with the 'off season' (~ month til the next sunday test & tune probably), I'll be going through and cleaning things up in the harness, wiring up some additional sensors that I should've hooked up a long time ago, working on the launch part. Don't need a track for that, can use the driveway or somewhere else with a clean surface. It's probably already fixed (it was sitting in a range on the map outside of where it was hitting on the dyno, and I just didn't go back and extrapolate across ahead of time), so we'll see on that one.
When I get to a point where it's a traction issue on the launch I will invoke one (or more) of the strategies to control power, probably wheel speed differential with a primary control being timing, it's hard(er) to add boost after you've pulled it back, and playing with the afrs can potentially create other issues, so.. that leaves timing. (and nitrous I suppose, but I'm not spraying it currently, and pulling timing on the spray works well too)