7THSIGN

I was curious, with upgraded exhuast and downpipe, front mount intercooler how much can you raise the boost? Also when raised to that PSI what would you be running, roughly in the 1/4 mile time? (considering its a very solid run) (Everything stock besides HKS downpipe HKS exhuast HKS intercooler and HKS boost controller)

DaleClark

iTrader: (55)

The flow mods aren't what you need to worry about when bringing up the boost, it's the ECU. The ECU won't fuel more boost properly and you'll be looking at a blown motor.

That said, if you have the above mods and an ECU, 12-14 psi would be safe. Not sure on 1/4 mile times.

Dale

iluvmy3rdgen

Get more fuel then up the boost. 1/4 mile times vary because every driver drives different. whether is be slower or faster they all drive different.

7THSIGN

Yeah I was taking in consideration it was a good driver with a good et time etc. Fuel mods and ecu I dont think its necessary to swap ecu's, however fuel upgrade's I can see being necessary what exactly would you need?

adam c

iTrader: (2)

If you don't upgrade your ecu, you will blow your engine. You should do some research before doing anything more.

Mid to high 12's

David Hayes

iTrader: (6)

You can use the Pettit "piggyback" chip for this. www.pettitracing.com. as everyone else has said, if you don't you'll be way too lean and blow the motor. i ran the stockers and the upgrade chip from pettit and ran about 14 psi. never 1/4 miled it though.

iluvmy3rdgen

Before you think it's not necessary I trying to help you out and I'm telling you to atleast get a re-mapped ecu.

rynberg

You're wrong. You can't boost over the stock 10 psi on the stock ecu. Period. This is a very basic modding rule that anyone owning an FD should know. I suggest you read through the links in the newbie sticky.

7THSIGN

So your telling me I cant boost to 11 or 12 psi with stock ecu???? I guess im used to Toyotas 3SGTE & 2JZGTE, just raise the boost with stock ecu.

particleeffect

correct!

onequikson

upgrade fuel system first

Cgotto6

iTrader: (8)

This is precisely correct. I wouldnt push your luck at all with the stock ECU. Rotarys are too nit picky with AFR's.

rynberg

It's got nothing to do with AFRs. The stock ecu is pig rich at 10 psi, rich enough to run with all of the bolt-ons very safely. The problem is that the stock ecu will FUEL-CUT at levels above 10 psi (the actual cut-off pressure varies by rpm -- do a search for the table).

7thSIGN: Forget Supras. This ain't a Supra. Read, read, read.

Initial FD

just because you can raise the boost with the stock ecu in toyotas and not directly see damage doesnt mean your not causing it, ours just let you know right away.

particleeffect

actually on an mk4, you aren't doing damage. the maf tends to compensate pretty well.

our ecu, as said before, simply isn't mapped that way. which sucks for us.

Initial FD

you are doing more damage then you are stock, and all engines take damage constantly, which is why you have to rebuild them

matty

Rynberg---this is news to me. plenty of people have run 11-12 psi on stock ecu. its been while since i have been stock but if i remember correctly i ran 11-12 psi on stock ecu. Not to mention that a dp adds 1 psi. tons of people run that mod alone. Whatever happen to the three mod rule anyways? did we do anyway with that one?

Mahjik

iTrader: (1)

The difference with Toyotas and the FD is that they use a MAF system and the FD uses a MAP. The MAF system detects the amount of air coming in and adjust the amount of fuel needed (to a certain extent). So, they are able to increase the boost up to a certain point without needed to reprogram/replace the ECU. The MAP system is a preprogrammed fuel map; so if more air start coming in that what it was programmed for, you can run into a lean condition and damage your motor.

Your next question is "why the hell did Mazda use a MAP system?". Well, there are benefits to each one and quite a few threads around talking about what's good about each system. However, that doesn't matter as that's how it is, period.

As far as increasing the boost, Fuel Cut is going to be the biggest problem when using the stock ECU. Fuel Cut is there to protect your engine from running out of the effeciency of the stock ECU fuel programming. The problem is that fuel cut is not instantaneous. Mazda realized that in cooler weather there will be some small amount of spiking. In these cases, it would be bad to have fuel cut kick in so there is some amount of delay that happens before fuel cut will kick in. The bad part is if the spike goes too high, then can be in trouble as fuel cut will might not kick in and you lean the car out enough to blow a seal.

These are some of the reasons it's recommended to upgrade the ECU when wanting to increase the boost level.

https://www.rx7club.com/3rd-gen-archives-73/stock-ecu-10-psi-myth-308996/

matty

wow..i am out of it.
Anyways i ran 11-12 psi on stock ecu and was fine.

PhoenixDownVII

I, too, was once a 3S-GTE driver, and has aspirations of aquiring my very own 2JZ powered Supra...

It was/is sort of dissapointing to find out that the FD needs ECU/Tuning to go anywhere from stock psi, but, in reference to my avatar, I like to do things right anyways.

It's just one more mod above the Supra's (And Mr2 I suppose) BPU setup. Intake/DP/CB but + ECU/Tuning.

I had an Mr2 @ 14psi and it was fun, but nothing compared to my FD. I don't mind the "hurdle" that Mazda's engineering provides, the outcome/benefit is worth the time/energy.

I do, however, wished the Rotary was "over" engineered like the supra. The FD just comes at its limits in most things (Cooling, Fuel, ECU, Boost settings) stock, so you have to replace a lot to move onward/upward.

Snook

iTrader: (12)

Telling you do the intake and full exhaust and keep the boost at 7psi and it'll blow away a stock rx7 at 10psi. You should be able to hit high 12s with a good launch and 10psi with those bolt ons. Take you're car to the 1/4 mile track Im curious to see if you know how to drive that thing you big ***** : )
Hey I am too don't worry I should be running 10s and Im not a good enough driver

PhoenixDownVII

LOL, If I am going to make more power, I'll go a bit further than 7-10psi buddy. I am going to wait until I can afford/do an ECU/Intake/DP/BC + Tuning all in one shot.

1/4 Track is gay. I'll give you some AutoX and lap times on some local tracks perhaps this spring/summer. That's about it.

Snook

iTrader: (12)

damn you are hardcore man I didnt know going to the track to see what 1/4 mile time it runs was gay

roadracing is more of my thing not autocross. but yeah bring your times bro I'll burn that ****!!

Yanni (very mature)

PhoenixDownVII

LOL, damn right I'm hardcore. Nah, 1/4 mile's cool and all as a measure of overall power and whatnot. But I just don't care what number's my car does really. I don't care to make hard launches either.

You know the saying, straights are for fast cars, turns are for fast drivers

Ha, come up to watkins glen or we'll meet halfway in NC or so and we'll see whatsup tuffguy :P

Dan (very more mature than yanni)

kuroi FD

phoenixdownVII i would love to see you and yanni race his car is stupid fast.

charlie(trying to lower maturity level)