Well, i must say, at this point and time im pretty damn confused. Last wednesday I went to the track and ran my usual setup, w/ my carsound high flow cat and my greddy sp cat back (2.25 inch). My best run was 13.4 @ 107. however i was hitting 109's earlier in the night.


So this week, i wanted to beat Direps time, so i unbolted my exhaust, ran the same kind of gas, same tires.....the only difference was i took my cat off and ran open downpipe.... i did dick around slightly with my fuel cuz however i ended up runnin a fine AFR.

Turns out, i couldnt hit more than 107 mph.....it spooled a lot faster, and boosted .3 psi more....however for some reason it didnt go faster LOL.

the temps are the same, humidity, everything the ****** same......Go Figure


Heres the datalog.....i tried to over lap them as close as possible......tell me what u ******* think, cuz i dont know.

 

Since you said is spooled faster, did you spin more? I would imagine it would be harder for you to get traction when to turbo spools faster.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SuperTeg95 &raquo;</TD></TR><TR><TD CLASS="quote">Since you said is spooled faster, did you spin more? I would imagine it would be harder for you to get traction when to turbo spools faster.</TD></TR></TABLE>

you're correct, it was hard to get traction, but i launched different,

 

prolly get more responses if posted in the drag racing section, but in any event, post the two timeslips before and after ... what were the 60' like on the two runs ?

greg

 

im not really worried about the times....i was running on shitty *** firestone tires that the civics used to come w/, im more worried about the fact that the car doesnt seem to make more power w/ an open downpipe, thats why i figured its a FI related topic.

Ill dig up the Time slips and post them shortly.

 

If your ET was the same, you just got to the traps quicker

(In other words you hit 107mph, but its a few more feet after the traps.)

The gainsville track is also inconsistent. Were you in the same lane on all runs?

 

Looks to me like you let out a little in first gear on the open exhaust pass, maybe due to wheel spin. You may have lost some momentum on that run, hurting your 60' time.
Thats all I see...

 

wierd...but nice times still!

 

I've done it time and time again on the dyno. Going from 2.5" exhaust and cat to open downpipe will pick up at LEAST 20whp. By the looks of your datalog it was running leaner with the open downpipe, which is normal. I can't read the numbers corresponding to the a/f ratio so i don't know if it was lean enough to loose power or not. Was the car ever dyno tuned? What a/f was it tuned to?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tony1 &raquo;</TD></TR><TR><TD CLASS="quote">I've done it time and time again on the dyno. Going from 2.5" exhaust and cat to open downpipe will pick up at LEAST 20whp. By the looks of your datalog it was running leaner with the open downpipe, which is normal. I can't read the numbers corresponding to the a/f ratio so i don't know if it was lean enough to loose power or not. Was the car ever dyno tuned? What a/f was it tuned to?</TD></TR></TABLE>

On that graph, w/ the exhaust attached, it was around 11.5 (yes i run it a tad rich), and with open downpipe, it ran around 11.8 afr. The car hasnt been on the dyno yet, only tuned w/ my techedge wideband.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bsmoak &raquo;</TD></TR><TR><TD CLASS="quote">Looks to me like you let out a little in first gear on the open exhaust pass, maybe due to wheel spin. You may have lost some momentum on that run, hurting your 60' time.
Thats all I see...</TD></TR></TABLE>

I noticed this too. Im thinking the quicker spool and added .3 boost gave you a little more tire slippage--you let off the gas and got back on it, or a hickup with ems.
Mase--care to share your map with me? I would like to see what timing, etc your running with your LS. Also to compare accel/decell and idle parameters. Im running .94 at the moment. If you could email it to me at turbocivx@comcast.net

Dan

 

I hate the way the ems logger logs the engine speed to 26k. I hate having to change the scales every time I open the log

Sorry I can't provide any insight to your prob Seems strange, even if you had slip at the start, you still should've had a high trap..

 

yes, i did have more tire spin, thats why i left off a hair, however, on both of these runs, my 60 ft's were like 2.24 and like 2.31.....anyways, i hate open downpipe, and i didnt gain anything by it....so im gonna stick to my tiny greddy sp for now...

 

Just for a little insight also. When I broke into the 12's I was running 2.25" exhaust too, so theres always hope.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mase &raquo;</TD></TR><TR><TD CLASS="quote">anyways, i hate open downpipe, and i didnt gain anything by it....so im gonna stick to my tiny greddy sp for now...</TD></TR></TABLE>

Don't give up, man. That's not the H-T way. You have to make more power with an open downpipe. Keep working on it til you find the problem.

 

1/4 mile times don't really give you a good indication if a mod works or not, too many variables come into play. In fact, I think the open DP worked TOO WELL! The problem I see here is not the exhaust...but your damn TIRES! Power is nothing without traction. Regardless, good luck on your tuning.