increasing boost -eliminating stock air box
 

i am new here. my name is jessica and i am mazdapunk87's gf.
i have a 2010 mazda3 hatch and an 87 rx7 tii swapped.


we just recently purchised a 2007 mazdaspeed3 and it has a short ram air intake. no stock air box just a cone filter.

on my rx7 i know that since i added exhaust and cone filter i increased the amount my turbo can boost, actually exceeding my waist gates, requiring porting of waist gates to stay with in stock boost range.


the 2007 has stock exhaust but a cone air filter. we do not have a boost guage installed yet and i would like to know if this modification would increase the amount of boost. i am a bit concerned that it is exceeding stock boost limits and thus could be causing damage to turbo and engine because of it . i am not sure how sensitive the tune on the stock ecu is i am not sure the limitations on the turbo but i would love to learn this information !!!!

i am a rotary head that would love to learn more about our new piston force induction vehicle

Dont worry about it. It might spike a little higher, but its not going to hold higher boost.

You are not increasing boost with just a cone filter. No worries.

It will spike higher as said. If you're hitting boost cut, then you can be worried, otherwise it's fine.

cool thanks! i just remember on my rx7 it was a huge issue cuz the 3'' exhaust to 2.5 racing beat revII

so i take it in this case the stock exhaust is enough restriction to off set the cone filter :)

i have right to be worried... my rx7 boost spiked alot untill i ported waist gates

the stock ecu does a good job at controlling boost until you open up the exhaust,

and its a wastegate ;)

i kept typing wastegate but my spell check kept saying it was wrong.

thats good to know though.

those of you who said it wont create boost spikes may be wrong.

last night we installed our boost gauge and while getting onto the highway in 5th gear WOT we spiked at 25psi.

2nd time while on the highway in 6th gear wot we hit 20psi


3rd time in 4th gear we spiked at 20 psi again

there was no hesitation no fuel cut no nothing. it just swong all the way over to 25psi and then back down to about 15.


our boost source is T'ed at the blow off valve like done in the write up on this forum.

why are you going into full boost in 6th gear? lol drop down a gear...or two...and did you ever see what the spikes were before the filter?!?! doesn't sound like it, so you could have had the same spikes before and just didn't know it.

your boost gauge is wrong. and what we said was: it might spike a little higher (which is fine), but it wont hold that boost.

My gauge has a peak function, and it never spikes above 21

wow ok. well we just bought the car and it had the filter on it before. and the turbo is brand new. exhaust is stock. only mods are the intake and the larger intercooler on top and forge bov.


stock turbo and stock wastegate should be able to evacuate all and any boost spikes on a stock engine.


droping it down a gear?? are you fricken serious? we dropped it into 4th hopping onto the highway at 55mph . its not reasonable to work around this, we want to solve the issue not baby the car because it spikes ridiculously under WOT and full load


thats what wastegates are for......

why do you say the boost gauge is wrong. thats a huge assumption. you dont know what our boost spike looks like personally.


the boost swings all the way over to just above 20, then as we continue the wot it goes back down to 15. it spikes but apparently does not hold. in 6th gear it holds longer then in 4th or 5th.


if you are claiming that our boost gauge is wrong. what facts do you have to sport the assumption.

rods connect to your pistons and go up and down, if you want your rods to continue to do that we suggest downshifting a gear or two, that amount of load so far down in the power band (especially in 6th gear) is not good for any FI car. especially one with as much down low torque like our car.

ok well if some one could please explain this to me. im into rotories. i know rotories inside and out . this is our first piston turbo powered car..

stop treating me like im doing something wrong, or im an idiot to try WOT in 4th gear. i didnt know it was a bad thing. why would wot be a bad thing in 4th gear. thats how i tune my rx7. 4th gear pulls on the highway. thats how alot of street tunes are done on an rx7


this is common sense to most. but i am not most. i am rotory not piston. so i didnt learn all this piston crap yet.


would some one, instead of giving me attitude or smartass answers, give me a true technical answer to this boost spike problem and why it occurs, if its a bad thing, or if its a normal thing?

fc3schick87, you have to listen to people on here and what they have to say. first there is something wrong if your spiking 25 psi on the stock turbo with just a larger intercooler and cone filter. are you sure there isnt a manual boost controller or something installed on your car? as you said you RECENTLY just purchased this car, many people on here have had them for years, and experience with this car is what matters most, it is different then any other car. keep going WOT in 6th gear and find out the hard way. why would you even want to do that, if it is slower then downshifting? it doesnt make sense. see if there is a boost controller or something you dont know about, there is no reason your boost should be so high, for what you have in your car.

^^what he said...and have you considered it being something else than just the filter? Have you even bothered to put the stock filter back on to see what its boost levels are like? And since your probably right in that we don't know EXACTLY what your boost is doing, how about a video...or two. You've got a boost gauge now...so share it with us what EXACTLY its doing since apparently we don't know what we're talking about.


Also we never said going wot in 4th was bad...I said going wot in 6th was bad and so did everyone else.

ITS A BAD THING, AND HOW ABOUT YOU STOP GIVING ATTITUDE AND ACCEPT THE WAY PEOPLE ARE ON THIS FORUM, AND SEARCH FOR YOUR ANSWER ON BOOST SPIKE. ITS VERY EASY TO FIND. 55 MPH IS TOO LOW A SPEED TO GO WOT IN 4TH.

wel i got my answer threw a pm from another member.

it wasnt so hard and it didnt take much to explain it to me.


as far as aditude from me towards you guys. i only treat those how they treat me. alot of people are giving me crap in this thread. like asking if i ever put the stock air box back on. well mr. i dont have one.



either way. if you guys are going to be assholes and idiots. then i'll just stop by another forum ...


it may be because i didnt know what i was talking about before. and i didnt understand the problem and i didnt know how to ask for an answer. but now i understand. so i guess this thread is done.


and those of you who think i wasnt taking advice. i would if i could understand the cause and effect, and the technical information behind the advice. which i dont quite know just out of thin air.....

Dont listen to these pussies that say WOT in 6th is bad. WOT under 3000rpm in any gear is not good. Now that we have that out of the way.....

You are right, I am assuming that your boost gauge is wrong. You are trying to diagnose a "problem" over the internet. Assuming is the only thing we can do.

First you say 25psi spikes...then you say "it passes 20psi". 2 things could be going on here: 1) your boost gauge is not accurate. im ASSUMING its a needle gauge since you said it sweeps. What brand gauge? is it brand new?
2) you arent reading the gauge accurately (no offense). Seeing the difference in 3-4psi in the split second that the boost spikes is going to be hard on a needle gauge (unless it has a peak function).

I considered for a second that someone installed a MBC, but you arent holding 20psi, so thats not it. You say a wastegate is for controlling boost, but this tinyturbo spools so fast, its hard to keep spikes under control. Even people using a tuning device find it hard to control spikes well.

My suggestion would be to get a dashhawk and see what the actual boost is spiking too. That eliminates human and mechanical error.

edit: so what was the answer you got?

I really didn't see how anybody was giving you attitude or smart ass remarks
I see you got your answer though

word of advice
if you continue to act like that you won't last long on this forum...things are ran diff here..REALLY diff from other forums

MS3 is not an RX-7?

if any one thought i was directing altitude at them i was not. its simply my own frustration trying to seek out answers when so many people are contributing to the thread but with no definitive answer to the problem. well some of you have explained yourself but not nicely....

i appreciate all and any advice with out the intent to throw it into my face. because i JUST dont know. and i need information to understand fully...


cone filter and aftermarket top mount. no boost controller, brand new turbo. 4th and 5th gear pulls (6th being an accident on my behalf not realizing how to treat a 6speed vehicle) resulting in boost spikes that drop back down to about 15 in a few seconds after WOT.

weather or not the gears were to high and the load was to much we had boost spikes, but now i know that because we were in the wrong gear apparently this is our own faults. 55mph being to slow to be in 4th gear on this car, ok i understand that, but i didnt understand that before. and i still dont understand why. a wastegate should be able to evacuate exhaust to prevent boost spikes...

i dont understand the "normal" and "Safe" reaction to load the turbo should be showing. i dont know usual numbers, i dont know what the turbo does under each gear. but i can tell you its not what i would expect from an rx7.


this is why i am so confused. why would the wastegate not be effective on this set up and allow boost spikes.... just doesnt make scene to me...


:) thank you. that makes sense!!!
i sent u a pm.

Because Mazda is cheap, just like the motor mounts, rear diff mounts (speed6 only), fuel pump, yada yada.


In all seriousness tho, the turbos on these cars are small, therefore have a very quick spool time. More specifically to ours, the hot side is smaller than other K04 turbos (say audi) which means that its easier to stay spooling (hence spikes) and also that means they're efficient to only about 18 psi vs others (again say audi) which can push 23 or so psi.

There's a LOT to learn about these cars, and to be honest this is probably the best place to learn about it, but its going to take patience and time. And I would take all your knowledge of the rx-7 (ok maybe not all, but most) and thro it out the window for the speed. They're completely different, tune different, drive different, handle different, its a different car.

You need bigger a bigger turbo on your RX7. :D LOL something like how I had on mine, before I sold her....MMmm....60mm compressor wheel hybrid...

http://www.laleetsgarage.com/pics/ph...7/IMG_0025.jpg

my rx7:

i have a t3/t4 hybrid with E trim, so its pretty high flow and even with 550/750 injectors on stock fpr i was maxing out my injectors with my tune. duty cycle was to high on the poor injectors even only at 5psi, which was my max boost possible with these injectors.

i have since increased my fuel pressure and i have decreased the amount of duty cycle needed to mantain 5psi. im ready to increase boost but im still tweaking the map to be stable up to 5psi. i literally just finished my fuel upgrade so its going to be a few weeks till my 5psi map is perfect and i am confident to increase the boost to 10psi

may not sound like alot, but i'm working on it slowly and doing it the right way...


i dont want a bigger turbo on my rx7.

my bf has a huge 62-1 on his rx7, and i just dont see the point in doing that to my rx7. i am not power hungery or looking to be faster and risk the engine with higher boost. and i am not willing to spend the money for the right parts for appropriate upgrades to support such a turbo.

i am conservative :)

The original poster is very emotional and sensitive I see, take it easy kiddo, they are just words on your screen from people you will never meet. Oh, and 6th gear is only there to get you up to Mazdas claimed top speed, other than that it's useless.

Any chance there's a test pipe or down pipe hiding under this car? Spikes or creep commonly occur after you open up the exhaust side on this car and you ask the stock electronic boost controller to work overtime.