sunnyxwala

i just put on my intake this weekend and its pulling really hard..feels great, but i need to know how much boost is too much boost??

Mahjik

iTrader: (1)

Anything over the stock boost is not a good idea without an upgraded ECU.

sunnyxwala

there must be some kind of measurment??, then why have the 3 mod rule??, all i need to know is how much boost is too much boost right now??, and why?

FD3S LIGHTNING

how much boost are you running right now

sunnyxwala

dont know, but a guy from rotary performance estimated it at 13-14 lbs, i will be checking it tommorow, but i would like to know what is safe

Bucrx7

Fuel cut on the stock ecu is 10.5 psi I think or is it 11.5. BE CAREFUL during the transition. If you spike to 14-15 psi then you diffinitely need to fix that problem.


Tony S.

mr_jonboy

I know fuel cut is higher than that on the stock ecu. B4 I got my AVC-r and a lot of other mods I had 12 psi and it was very strong. Now with the AVC-r if I get up into the 12 psi level it seems that it is cutting out of power (prob. fuel cut). I am running stock boost now...until I get an ECU just to be safe.

sunnyxwala

yah i will be checking it tomorrow, thanks for the info guys

Mahjik

iTrader: (1)

Even without fuel cut, I don't think the stock ECU will safely provide enough fuel to have a safe air/fuel ratio above the stock boost level (around 10 PSI). I wouldn't trust it either way.

suganuma

1993 rx7 montego blue
****Custom 2 dual cone intake
****Greddy Sp exhaust
****Bonez Downpipe
****Greddy hard pipe kit/w elbow
RP aluminum AST
Blitz boost controler <--not installed
Blitz boost guage <--not installed
Blitz turbo timer <--not installed
Autometer air/fuel ratio guage <--not installed

17" TSW VX-1 wheels
Pioneer p-730
Custom box with 3 JL 10w3
1200 watts digital

yah and its automatic so what??



before you installed all of these power mods you DEFINITELY should have made the boost gauge your first mod and the boost controller your 2nd mod.
put boost back to stock until you get an ecu. 13-14# is around 85% of injector duty, but you dont have the fuel maps to run that correctly. im suprised you arent hitting a boost cut.
the car will run great for alittle while while youre all leaned out and making power, but then its going to crap on you.

my advice - from day one of mods keep your boost at stock levels until you get an upgrade EMS with new fuel and ignition maps for boost higher than 10#

-Nic

JoeD

i personally would not push it past 12 PSI on stock ECU. maily because the ECU cant handle it, and the stock IC looses its efficiency past 12 PSI.

suganuma

where did you here 12? did you dyno test it?
ive always heard 14 so ive kept my max boost below or right at 13 and that was always from very reliable sources....

i wouldnt push the stock ecu at all.....2 # is NOT worth a new engine man...

maxpesce

Stock BOOST cut happens at around 14psi but the stock maps are only good to around 10 psi at max RPM in the mid range 4500-6000 rpm there should be enough fuel for 12 psi, I am running 12/8/11 on my car with a stock ecu
Yes mine is also an AUTO and with our 7000rpm redline we should be a little safer on fuel delivery, its in that last 1000rpm where the 5 speeds run out of fuel on 12psi boost.

sunnyxwala

i dont have a controller hooked up, do you think that i will be safe for now if i dont redline it at 7000k??

artguy

guy you are gonna blow that thing up arent you?

Ive been thru two motors...three sets of turbos....dont waste your money. if you dont park that car and get it set up right you will be out a car and have a five - ten thousand dollar bill staring you in your teary face. odds are you are already cooking the seals. dont risk it anymore. simply put it down for a while and get it set up right...listen to these guys. it will be down a lot longer if you crap your apex seals out the tailpipe...or start burning the antifreeze from heat damage to your side seals.

if you have to drive it...get a boost guage and dont push it past stock levels...but that will be hard to do.

be careful...

good luck

jason

maxpesce

Do yourself a favor

INSTALL THE BOOST GUAGE AND A/F RATIO METER !

then just make sure you don't excede 12 psi BOOST AND the A/F meter shows AT LEAST 2 BARS RICH (Green) whenever you are over 5psi boost

a brief spike to 13-14psi during transition won't hurt you as long as the boost stablizes at 12psi or less by 5500rpm.

neevosh

Does anyone have any proof that the stock ECU can't handle more than 10-12 psi without running lean? Like done any testing with a wideband to check the A/F ratios. The 3 mod rule and such have become common knowledge but I've never seen any proof to support it. Not saying it isn't true, but hard evidence would be helpful. And here is the factory overboost fuel cut #'s. Got these from another site.

RPM ABS. CUT OFF(PSI) SEA LEVEL CUT OFF(PSI)

1000 26.5 11.8
1500 26.5 11.8
2000 26.5 11.8
2500 26.5 11.8
3000 26.9 12.2
3500 27.1 12.4
4000 27.5 12.8
4500 28.0 13.3
5000 26.9 12.2
5500 26.0 11.3
6000 25.8 11.1
6500 25.4 10.7
7000 25.4 10.7

mr_jonboy

Good question, any data runs to back up the stock ECU and what it can handle?

BrianK

where did you get this table and what is the center column? (what is ABS. cutt off?)

just curious

mr_jonboy

I am guessing it stands for Absolute cut off. Gage pressure + atmospheric pressure (14.7 psi) = absolute pressure. But that is my guess only.

rynberg

Those numbers are posted on Rob's or Steve's site. Yes, ABS stands for absolute pressure, the third column is manifold pressure. Good post Neevosh, as you can see Sunnyxwala, the stock map can handle a couple of PSI higher than the stock setup.

Wade

iTrader: (1)

This stuff isn't a mystery guys, those fuel cut numbers come right from the factory manual.

As far as testing the a/f ratio with the stock ECU, see my web page, I have some test results. www.wvinter.net/~flanham/wlanham ...Go to "Myths - 3 mod rule".

I will probably never test more than 10psi on the stock ECU unless I try a Fuel Cut Defensor, because any time you run much more than that you are running the risk of hitting the fuel cut. Those who are getting away with running more boost won't get away with it in higher gears, just lower ones because the fuel cut only kicks in after so many seconds (it allows for spikes). Driving around in a car bouncing off of fuel cut is stupid and I will probably never do it. Give me an FD to destroy and I'll test it.

Wade

mr_jonboy

So from your data, the stock setup is 10:1 A:F ratio, correct? Isn't that a little rich from what it could handle. I mean from the factory they always set them up rich to be conservative. Can they not handle in the area's of around 14:1 and still be ok. My buddy tuned his S2000 from the factory 8-9:1 to around 13-14-1 and got 10 hp which is a huge gain for that car, plus he saves gas. can the rotary not handle those A:F numbers? Good data BTW.

suganuma

i wouldnt lean out a rotary past 11.5 or 12 personally....
taking it to around 14 like you would on a piston engine is asking for a blown motor on a rotary. keep it rich.....and safe.

mr_jonboy

So with that being said and the table of data listed above, you can take the thing above 10.7 psi. The table is showing 10.7 psi at 8000 rpm is still making 10:1 A:F ratio, right or wrong? If the thing can handle 11.5 or 12:1 and still not be "lean" than why not do it, thus getting more boost and saving gas in the process. Someone correct me if I am talking out of my @ss.