fastest 1/4 time on stock ECU/IC?
 

Hey guys, i was wondering who has run the fastest 1/4 mile time on the stock ECU (no piggybacks or reflashes or anything) and stock IC.
i went back to the track again and squeezed out a 12.51@110mph, which from what i'm gathering is pretty fast for the stock ECU and IC at 10psi. this was also on regular street tires.

my mods are:
apex'i intakes
custom downpipe, hiflow cat, RB catback
TB mod, non-seq, removed emissions
MBC set at the stock 10psi

so what's the fastest time someone has run in an FD with the stock ECU and IC?

anyone?

that sounds pretty good.

Well, that is faster than any magazine ever tested one, for sure.
Great run!

wow! thats realllly good for stock ic and boost, especially that trap....damn!

That does sound like a fast time, but it sounds like you might be approaching the safe limits of what you should do with a stock IC & ECU. Unless you've got data to prove otherwise (for instance a dyno sheet demonstrating safe wideband A/F ratios vs. RPM), I'd recommend an ECU and an IC ASAP.

-s-

i dyno'd in february and the AFR was mid 11's on the exact same setup. that was about 3 months ago though, but i havent done anything to the car. mid 11's should be plenty safe.
i suppose i should dyno again to see if the power went up somehow (though i dont see how it could), but as far as it being at the limits -yeah, its definitely at the limits of boost and the crappy IC, but it's obviously still at 10psi with good AFR's. if it was running more than 10psi it would be fuel cutting.
when the boost comes in it spikes to 11psi for a split second and holds 10psi all the way to redline. (crappy MBC)
110.7mph seemed a little high to me too, but i'm not sure.

i was just curious who has run on the stock ECU because its usually the #1 thing to upgrade after intake/exhaust with FD's, and i never hear about people making quick passes on the stock ECU and IC. they just upgrade to a PFC/basemap immediately. as far as i can see, the stock ECU does better than everybody gives it credit for, as long as you decide to keep the boost at 10psi.

are you sure its a 100% stock ecu, there are many companies over the years that have reprogramed them

that must just be some ridiculous reaction time and an awesome launch. good job

i'm pretty sure its 100% stock... i've overboosted before and its hit fuel cut.

the time doesnt start til you cross the starting line (unless its bracket racing).
you can sit on the start line for 30 seconds and run a 13.5
so the r/t doesnt really matter

id have to disagree


sounds about right... i was at the track for the first time on the new setup this sunday and ran a 12.4 at 109mph on 10psi untuned (high 9's afr's) on a gt42 with soft launchs slipping the clutch... managing a 1.9x 60ft

just for shits and giggles and for some good logs



quick car for stock equipment though :).... good work

Good man. I didn't mean to doubt you; just wanted to hear the rest of the story. You've obviously done things the right way: change something, and verify that it's working well (safely and reliably) before pushing it to the limit. It seems like many of the people on these boards have yet to learn this.



I agree, but it's only because the original settings are so rich to begin with. Our ancient ECUs work pretty well, within their limitations. Just for reference, the original Intel Pentium CPU was introduced in 1993; clock speed was a whopping 66MHz.

-s-

i've always wondered if the newer jdm cpu was a direct swap in? i know it's faster (32bit instead of 16 bit or something) and it's obd2 (which would make reading any codes so much more convenient.) would also alow tuning thru diagnosis port since it's obd2 by some of the common simple plug n play tuners

as i said in other thread i doubt u are making only 265 to trap almost 111mph. noone is doing that. people are trapping 110mph with 300 rwhp for the past 10 yrs. is your boost gauge faulty?

I had trapped 106 MPH on 10PSI/stock ECU with really shitty kumho 712s spinning mostly through 1st and 2nd, but almost 111MPH seems really high for 10psi. Not doubting you, just saying.. When I was running my Pettit ECU and 14psi I was only trapping 113-114.

No ,they are not interchangable..

i was thinking more along the lines of shifting r/t and throttle control. :)

and boo to the jdm ecu not being interchangable :(

Sounds like a great time and a healthy motor! Either your boost gauge is messed up or you can launch reallly good.

I got 13.2 at 109 with a 1.9 60ft.

Mods were a racing beat back box, apexi filters - thats it.

i didnt notice anyone say anything about weight? maybe jacobcartmill is a smaller guy. take passenger seat out. run on fumes in the tank, lighter wheels and tires, simple things. isnt the rule of thumb .1 seconds for every hundred pounds? (i realize this changes with hp and many other settings, im just repeating what someone told me before)

I'm sure you are making more than 256rwhp. I made 295rwhp with similar mods at 10psi awhile back. It may have been a very hot day when you dynoed, but on the average if your motor is healthy you should have no problem making close to 300rwhp with all the bolt ons,IC and the stock computer. The problem with the stock computer is that you are running the risk of blowing up since there is a possibility of overboosting with those mods and the ECU will not help you since its only mapped to about 12psi (I believe) and the fact that the fuel cut comes in pretty suddenly is also another factor in damaging engines.

salva, i understand what you're saying, but it doesnt overboost as the setup is non-sequential and the boost is reliable, it doesn't boost creep (probably due to my hi-flow cat) and it doesnt hit fuel cut. this is why i keep it at 10psi

1life2stories, i weigh 135lbs and ran with a little under 1/2 tank of gas. i weighed the car with ZERO gas several months ago and it was 2680lbs. i had about 8-9 gallons in the tank and gasoline weighs ~6lbs/gallon, so thats ~51lbs of gasoline.
2680 + 135 + 51 = ~2866lbs race weight (fuel and driver)

for the people that are saying my boost gauge is reading incorrectly (low):
if you hold more than 10.5psi for a second or two the ECU will fuel cut. what i'm alluding to is the fact that my boost gauge CAN'T be wrong, because if i were holding more than 10psi it would be hitting fuel cut.

wow..nice f'ing trap

i dont think fuel cut happens that quick..

are you sure? 2 seconds is a long time when you're hammering at full boost. in fact, i think its more like under 1/2 second

been 7 yrs since i was stock ecu but if i recall i used to boost 12psi on the stock ecu.

https://www.rx7club.com/forum/showpo...6&postcount=46

i dont know how credible that guy is, and the post is 5 years old, but i've heard that before -that you can overboost for under a second before the fuel gets cut by the ECU

and this is from the same thread:
https://www.rx7club.com/forum/showpo...1&postcount=17

this is like fd 101....surprised i cant remember. pretty sure u are wrong though.

i could be, but I'M pretty sure my boost gauge isnt reading incorrectly, in which case none of this fuel cut stuff would even matter :)

agreed

officially fuel cut happens at 12 psi. if your gauge is showing you that it's cutting at 10.5 psi then your gauge might be readying 10 psi when it's really at 11.5 or so. mines off about 2 psi and about 4 or 6 on vacuum. it's a piece of shit pettit autometer.

and what did you do to drop the weight that much that's a significant reduction. is it an R1 or touring or base ?

i havent done anything to drop weight except remove the spare tire.

its a 93 base model

aw my touring packs on another couple hundred pounds at least. booo :(

whats ur car weigh again


also i dont think its 12 psi either on stock ecu. keep going higher.......

pettit said that the stock fuel cut comes on at 14.8 psi but it doesnt mean that you can run it that high. just get an wideband and keep a eye on it if i goes over 11.5 then i would shut down. alot of things factor in on AFR. temperature and altitude will change it alot. that is why tuners tune the ratio low so if it is hot that day then it wont be affected when it is cold.

thanks for that tuning tip.
.
.
.
.
.
oh yeah, BTW, did i mention the car is running 10psi?

yea i read that. also to add.. AFR on a dyno is not as accurate either because the exhaust cools as it moves to the tip. right in the down pipe is the best

also how do you like non sequential? and when are you seeing full boost at?

it's also reading AFTER the cat in my case


i did the full non-sequential mod and in 4th gear i get full boost around 3500rpms

eh i always heard 12psi but i also always thought that was wrong. when i forst got my car it had just a downpipe and was spiking to 15 without cutting. but later it did cut at around 12, which was lame. but w/e

Well that explains the weight. Hell base models are the lightest ones.

i just got back from the track i ran 13.0@ 105 1.9 60ft mods: pf cat back,k&N drop in, short shifter

You sure it has the stock downpipe?? I didnt realize a catback would make that kind of difference.

no kidding. a downpipe would benefit more than a catback anyway it seems

I have some Racing Hart C2 18x8.5 front and 18x9.5 rear for sale $1000 3-piece rims in good shape off my 93 rx-7. I also have my stock twins for sale that are coming off next week for my single turbo upgrade $500 work perfect! You can email me at flyassgator@yahoo.com

nice post.
also, your sig says the fronts are 7.5", not 8.5

yes, it is the stock downpipe. i hope to get a downpipe this week and head back to the track anyone have one for sale

what power difference?

people get 13.5 all the time on a completely stock car. the mph seems inline to me as well. maybe slightly high. so i dotn know what the hell u are taking about.

Boost cut happens much higher and is not a set pressure, it varies with RPM. I ran 12-11-12 psi on stock ECU with DP, CB, M2 CAI, Underdrive Pulley, and MBC for a couple years (stock IC and Cat).

Jack