Jim_rx7

Hey guys...

I have a UK FD with blitz twin induction kit, decat pipe (I still have pre-cat off the turbo), HKS exhaust, HKS SSQV BOV.

Currently running on stock ECU.

I have a XS Power SMIC to fit, but someone suggested that fitting it without a mapped ECU could cause the car to run lean??

Would just like some clarification on this if possible, and if it's safe to go ahead and fit it?

thanks

IRPerformance

iTrader: (41)

I would not do any additional modifictions before upgrading the computer. The stock intercooler is a bottleneck and a larger one will change the airflow through the motor. Further, I would install the stock main cat and get a downpipe instead.

BuffDaddy915

What he means is that tha boost will up and higher boost without fuel/air control from an aftermarket computer will make tha car run lean.

Jim_rx7

Surely all a larger IC/SMIC does is help keep the intake temps lower, then in thoery allowing you to run more boost as long as you have sufficient fuelling.

So running stock boost with a larger SMIC/IC, I don't see where the problem would lie?

Might be wrong though.

PS: I am on the hunt for an Apexi PFC.

dgeesaman

iTrader: (7)

Larger intercooler generally does increase boost levels unless you have an adjustable boost controller to re-adjust it. The bigger flow paths cause lower restriction.

Also, the lower intake temps do increase the amount of oxygen reaching the engine. Although this isn't normally a problem for the stock ecu if your boost is tuned down to 10psi.

Dave

Jim_rx7

So it "should" be ok if not boosting above 10psi?

Jim_rx7

This is a comment from someone else on another board....

"i am running without cat and will be putting my big smic on soon.

basically in my opinion i can see there are too sensors to detect air mass and flow etc. the important one being the map sensor which takes a reading off the back of the plenum.

if it is a cold day this will fuel in a certain way and in the warm it will compensate.

if i put the big smic on all i am doing is slightly lowering boost and making the boosted air cooler as if a cooler day. if this is within the ecus limits and map then it should be fine, perhaps if i was boosting in minus temperatures with a huge ic then it could but i cant see how. the ecu detecs the air temp in the plenum so after the ic.

as for decat if you have boost spiking just get a boost controller - i have the greddy e-01 and i set my max vaue and now it will not boost any higher thus meaning no overboosting and no running lean.

this is my opinion so you can obviously make your mind up and i would reccomend the apexi but i think it comes over reccomended sometimes."

Does this make sense, or is he talking rubbish?

dgeesaman

iTrader: (7)

Yes. If you boost above 11psi, I would install a boost controller (manual or electrical) even though you intend to buy a PFC later. The reason why is because the PFC's boost control is far inferior to a separate unit. If you're adding flow mods one at a time, it's reasonable to simply use your boost gauge for a before/after and stop when you go over 10psi. Usually the boost doesn't go up until you after install a couple of mods.

The whole thing about temps, sensors, and crap comes down to real-world practicality - someone went to the trouble of measuring AFRs and found that as long as you keep your boost at 10psi, your afrs stay safe on a stock ECU.

You can pretty much install any flow mods you want and set your boost at 10psi with an adjustable boost controller - with one exception. The exception is a fully decatted exhaust, which will often cause boost creep. Boost creep is beyond the ability of a boost controller, and if you read the FAQ or just google you can learn more about it. As long as you leave a cat in the exhaust, you have very little risk of seeing boost creep.

Dave

Jim_rx7

I still have the pre-cat in (off the turbo - downpipe), but the middle section is decatted.

So it isn't a complete decat system, so again... it should be ok?

Cheers for the info mate. I'm gonna fit the SMIC and then sort out a small boost leak issue and if I notice it go over 10psi I'll get a boost controller of some sort.

silverTRD

iTrader: (37)

u should be fine, but every car is different and flukes have happened in the past.

u should swap out ur precat for a dp and install a highflow in place of the mp. much more reliable(i.e. heat) more power, still safe for boost creep as well.

Jim_rx7

So I should get a downpipe instead of the pre-cat and put what in place of the midpipe? A high flow cat? Currently the midpipe is a straight through decat pipe. 3" S.Steel.

I do have a jop stock downpipe sitting waiting to go on the car (no cat, unlike the UK cars), but should I wait to put this in until I have the Apexi? (or else it would be complete decat).

cheers

NissanConvert

iTrader: (1)

Yes, you should get a down pipe and replace your mid pipe with a high flow catalyst. The stock precat is a heat sink that's been linked to all sorts of nasty problems. Alternatively you could pull the turbos off and port your wastegate then run the downpipe and the midpipe. But- even that's not 100% on the stock turbos.

Jim_rx7

Still don't know what to do with regards to fitting the SMIC without an apexi....

Have a read here....

http://www.mazdarotaryclub.com/forum...ad.php?t=37153

People say don't do, people say do.

Does the Rx7 have a MAF or MAP sensor?

This is also from a freind...

"I'm not familiar with an RX7 but i can explain how the whole system works hollistically.

in a normal scenario, air goes in to the compressor end of the turbo, its pressure increases and it also gets hotter. this air then goes into the engine and is combusted.

in an intercooled scenario, air goes into the compressor end of the turbo, its pressure increases, it gets hotter. It then goes into the intercooler at which point some heat is taken out, this makes the air more dense (has the effect of increasing pressure) and then the air goes into the engine and is combusted.

the whole problem you would have is depending on how the fuel system on the car works. There are two types of sensor MAF (mass air flow) and MAP (metered air pressure). If you have MAF, then its no problem your ECU will adjust for the increase in air accordingly (as mass cannot be created or destroyed).

However if you have MAP you will have a problem because it works off inlet pressure. By the time your air enters the combustion chamber it will be running lean. The ECU thinks there is less air than there actually is so doesn't spray enough fuel in.

hope this helps"


I just don't know what to do tbh... I wish either everyone said it would be ok, or everyone said it wouldn't! lol.

rynberg

THERE IS NO PROBLEM WITH RUNNING THOSE MODS ON THE STOCK ECU AT 10 PSI. PERIOD.

And yes, get a hi-flow cat and a downpipe.

Mahjik

iTrader: (1)

In a sense, he is correct (and the FD uses a MAP system). There are basically 2 issues to deal with:

1. Increased boost
2. More CFM

Your friend is talking about CFM. For instance, a large single turbo is going to have more CFM at 10 PSI than the stock twin turbos at 10 PSI (which is why it will make more power at the same pressure). Having said that, it's been proven the stock ECU has enough fuel for bolt-on mods at 10 PSI.

Intercoolers can increase boost depending on your other mods. If the turbos have to push say about 15 PSI from the hot side to make 10 PSI on the cool side; then putting in a more efficient intercooler will allow the turbos to work less to make the same power (i.e. say they need to make 12 PSI on the hot side to product 10 PSI on the cool side). Since your turbos aren't working as hard, they can begin to overboost but it's not typically an issue.

So, as you can see, an intercooler upgrade can also help reduce some stress on your turbos.

Jim_rx7

Ah... cheers for the info.

Will be fitting the IC tomorrow.

Hopefully nothing's gonna go boom!!

rynberg

Since this hasn't been addressed yet, how are you ducting the IC? A bigger SMIC without ducting will perform worse than the stock IC....this is proven.

Jim_rx7

Like this....



It's crude, but it's the ducting from the original airbox with another bit attached to it which is the same shape as the IC. This is then taped to the IC. This way it forces the air through the IC.

I will be getting something made up of fibre glass in the future.

The Aluminium sheet on top is simply to hide the crudeness of the plastic underneath until something better is fabricated

fdeeznutz

Frostycrowd

iTrader: (9)

does anyone have any documented gains from upgrading the intercooler after the other bolt-ons?

i have a full exhaust (with hiflow cat), apexi intakes, non-sequential running at 10psi. my AFR"s on the dyno were around 11.2:1
i'm thinking about getting that XSPower IC kit, but i'm wondering how much more airflow it will be, as i like my 11.2 AFR

again, i am on the stock ECU, stock IC, stock 10psi


edit: jacobcartmill posting here. 93 FD base model

Jim_rx7

Well finally done!



Gonna get some ducting made out of fibre glass. The current one has just been modded slightly.