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-   -   Please analyze my quarter mile times! (https://www.rx7club.com/time-slips-dyno-121/please-analyze-my-quarter-mile-times-447758/)

neit_jnf 07-27-05 10:33 PM

Please analyze my quarter mile times!
 
2 Attachment(s)
First time ever on the strip, on any car for that matter, only got 2 runs.

My car is a touring with bose tube and spare removed, 1/3 tank of gas and I weight about 220 lbs. The car dynoed 315 whp at 13.5 psi, for the runs I lowered it to 13 psi. The car was also heat soaked from waiting in line for so long...

First try (right lane car #990): 31 psi tire pressure, 3~4000rpm launch, got nervous with the wheelspin so I pressed the clutch in and kinda slipped it, I'm not sure what I did

rt .5659
60' 2.2579
1/8 8.78 @ 83.48
1000' 11.2561
1/4 13.36 @ 107.34


Second try (right lane car #990): lowered pressure to 23 psi, 4000rpm launch, bogged down

rt .4040
60' 2.3228
1/8 8.94 @ 83.52
1000' 11.4261
1/4 13.53 @ 107.64

I have a M2 Large IC, do you think adding a puller fan behind it is a good idea?

I thought I could hit mid/high 12's what do you guys think?? Is the car capable of this and I only need to practice? Or do I need more power? Ideas?

jack_arss 07-27-05 11:25 PM

your car has 12's in it, you just need to go to the track more.

the 60fts are lacking, a good launch on street tires is 2.0x, a great launch on street tires is 1.9x.

btw-this is marksmazda..are you going to the import drags on saturday?

A.W.O.L 07-27-05 11:59 PM

the trap seems low for that kind of power

tt2323 07-28-05 12:02 AM

I agree your trap is fairly low. I ran lesser mods 12psi and was running 13.0@110 with a awful 2.35 60ft

neit_jnf 07-28-05 07:01 AM

I also was dissapointed at the trap speeds, I thought maybe the heatsoaked IC robbed my power? I also felt it misfire at about 7000 rpm, it never did that before, maybe the new walbro is making it too rich? Or the plugs are worn (12k miles)? I don't know. I'm getting new iridium 9's to put on next week. And hopefully a friend can let me use his wideband to log the afr's cough-mark-cough. :p:

neit_jnf 07-28-05 02:11 PM

any pointers? tire pressure, launch rpm, dump or slip the clutch??

Force13B 07-28-05 02:17 PM

Lower your launch RPM's, and slip the cluch out as you go, for the first 30ft or so. This is what i've read about launching the 7 on street tires. I could be way off base, haven't taken my car to the track yet so you might know more then me.

rotorsownyou7 07-29-05 07:52 AM

Damn, that should be capable of mid 12's Just go to the track like 20 times and try out different things.

turbogarrett 07-29-05 04:23 PM

I used to run a spal slimline fan on the back of my m2 large and it really helped minimize heatsoak problems.

2FAST7S 08-01-05 10:44 PM


Originally Posted by neit_jnf
any pointers? tire pressure, launch rpm, dump or slip the clutch??

lower tire preasure to about 17 psi, slip the clutch from about 4k rpms and shift without lifting as fast as possible!

Snook 08-03-05 07:35 AM

12k miles on the spark plugs is your problem
I ran a 13.5@106 my first time at the track with 10psi and only mods intake, dp, cb
your 60 foot time isn't that bad for the first time. change the plugs and get a 2.0 60 time and you should never get into the 13s again
do you have a midpipe?

neit_jnf 08-03-05 12:03 PM

stock cat, I'm afraid of boost spike/creep... Thinking about getting a metal highflow cat in there...

Snook 08-03-05 12:22 PM

you didnt say what ecu you're running?
spikes can be controlled with a boost controller and I wouldnt expect any creep since you're running 13psi already.

the stock cat is killing your power. That should have been upgraded before the intercooler. you can still get into the 12s with your setup you'll just have to turn those 60 times into 1.95s

neit_jnf 08-03-05 12:40 PM

here's my dyno and mods:

https://www.rx7club.com/time-slips-dyno-121/my-first-dyno-wohoo-d-444016/

Snook 08-03-05 01:04 PM

12.5 is real lean in the high rpms!
I would not run the car like that

First, I'd not run high boost again until I switched out ecus

The pettit unlimited is a much better choice and run 12psi MAX but you can have a midpipe too you'll pick up tons of power.

with a 1.9 60 foot expect mid 12s@111 every run at 12psi

neit_jnf 08-03-05 01:34 PM

As I understand it, the Pettit is more agressive than the M2, so I chose the M2 to be on the safer side. Supposedly the M2 is good to 14 psi, but the dyno operator told me the pump wasn't keeping up. I have since upgraded to a Walbro high pressure pump and lowered the boost to 12 psi.

The dyno wideband was in the tailpipe so it was reading leaner than it actually was because of the cat. I was probably at the 11.7~12.0 level when I leaned out. I'm getting a wideband loaned from a friend and new Iridium 9 range plugs. I'll do a couple afr's logs starting at 10psi and gradually increasing back to 13.5 to see if the pump helped. I'll post the results when I get them.

So far the pump increased my fuel consuption, I was getting consistent 20 mpg 85% highway 15% city and now I'm getting 18...

jack_arss 08-05-05 10:03 PM

your over running your stock fuel presure regulator. from what i've read, a non adjustable FPR will not lower your fuel presure back to stock, it's just a ratio of the presure going into it. basicly, if you have 2psi going in, and 1psi comming out, then up the presure to 4psi goin in, you will have 2psi comming out.


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