evildky Posted October 31, 2005 Share Posted October 31, 2005 so I went to the drag strip saturday, my set up is pretty basic, junkyard motor/turbo extra boost and fuel, 2.5" crush bent exhaust, previously I had run a 13.010 @ 107.75 with drag radials about 24" diameter on a 1.9 60' at 9 psi, since then I added megasquirtnspark, FMIC, DSM injectors and upped it to 15 psi on some 26" drag slicks, this time my best was a 12.814 @ 106.64 with a 1.7 60', I understand the tires giving the better hook and 60' and the I/C and piping causing a bit more lag on the bottom end but the topend is quite a bit stronger and the drop in trap speed just baffels me I'd think the larger lighter tired would yield a better trap speed, any of you hardcore drag racers got some insight? Quote Link to comment Share on other sites More sharing options...
Guest ON3GO Posted October 31, 2005 Share Posted October 31, 2005 15psi with slicks, w/ a standalone and only a 12.8? is it very very mild tune? this in a 280zx or S30 Z? still congrats on the new best time, i think you have Plenty more room to go.. i would mess with your fuel setting. whats your a/f ratio at? mike Quote Link to comment Share on other sites More sharing options...
evildky Posted October 31, 2005 Author Share Posted October 31, 2005 my car is an early 71, weights about 2350 with me in it! as fro the A/F I still gotta get a wideband, I think I am still a bit rich but afraid to lean it out without a wideband to know for sure Quote Link to comment Share on other sites More sharing options...
Thumper Posted October 31, 2005 Share Posted October 31, 2005 I think you are down on power on the top-end. With 13 psi in a 2600 lb car with me in it I was running 12.7@107 on street tires. 60ft 1.998 Quote Link to comment Share on other sites More sharing options...
Pyro Posted October 31, 2005 Share Posted October 31, 2005 Well that was a good time for 9 psi and no IC, then the extra boost and the upgrades should had yielded some really big gains, at least in the mph department. And I don't think atmospheric conditions would be that bad to not see gains in HP from all the upgrades. So, I think you have some problems there (as you already know). I see that you are using ignition control. How much timing are you using? How is the clutch doing? Maybe it is time for a little data logging with a wide band 02. Are you measuring boost on the manifold (after the IC) or on the turbo? Gear ratio changes, or in your case, tire height changes, don't effect the trap speed that much. Gear changes effect et's much more dramatically. In a 2350 lb car (car plus driver) with a L28 and 15 psi of boost, I would expect 115 mph in the 1/4 mile. Could be ignition timing, fuel ratio, clutch slippage, or boost leakage (to name a few). I know that this is a bunch stuff and is no help what-so-ever. But good luck finding the problem. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 1, 2005 Share Posted November 1, 2005 I think you are down on power on the top-end. With 13 psi in a 2600 lb car with me in it I was running 12.7@107[/email'] on street tires. 60ft 1.998 Holy crap Thumper that's quick! That was on stock EFI or what??? Mods list please! My car weighs 2300 (weighed on a truck scale), about 2600 with me and half tank of gas as well, and yeah I was figuring about a 12.8 at 107 for my hp (~240 rwhp) at 14psi. I played around with a Gtech Pro SS, and while it gave me crappy 1/4 times due to my crappy launch and 2.7 second 60' times, it did give me consistent 106-108mph trap speeds. About running that on Megasquirt yeah I would say that's down on power... who was it that made like 200+ whp on stock 7psi? I know I read that a few months ago. Quote Link to comment Share on other sites More sharing options...
Pyro Posted November 1, 2005 Share Posted November 1, 2005 I think I over estimated the expected 1/4 mile mph. I'm thinking you should do 111 or 112 mph with 15 psi and a 2350lb car. That assumes about 250hp. So you are about 5 mph short or about 25 hp. But, of course I could be completely wrong. Quote Link to comment Share on other sites More sharing options...
evildky Posted November 1, 2005 Author Share Posted November 1, 2005 I dyno'd 216hp with 9psi on stock managment, I'll be back tot he dyno in a coupla weeks I'll post results, I just need to get the ms2 and wideband to help make tuning quicker and easier Quote Link to comment Share on other sites More sharing options...
Guest ON3GO Posted November 2, 2005 Share Posted November 2, 2005 thumpers car was a 280zx t-top, gutted, junkyard style motor really, P90A head, stock efi, adjustable fpr, stock t3 and reg ole street tires. mike Quote Link to comment Share on other sites More sharing options...
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