Okay, how can i kill my boost.

Post by **thekawaii** » Wed Sep 07, 2005 4:33 pm

Sorry about the weird titleyeah, it's too late to go back to N/A.I already cut my original piping and there's no way to go back.

So. I have some problems with injectors and tuning, plus I don't want to blow up my engine. So, I decided to build no boost until i came up with new solution.It's would be nice if i find internal wastegate actuator that work at 3 psi (what safe range that stock 270cc injectors can handle) , but since it's impossible to find one, let me just kill the boost.

For sure, ditching the hot pipe is not a good idea because turbine will have no air resistance, turbine and compressor gonna spin like over 150000 rpm, evantually destroy itself.so no playing with pipes.

Another way I figured, I'm just gonna open the internal wastegate by disconnecting the actuator handle, but i also thought that 'what's going to happen to the small gate if all the hot exhaust gas goes though there?' I think it'll probably damage the gate.... if i'm correct. (and it'll still make build some boost and lag crazy)

So, non of my method will work. Any idea how to kill the boost? (make it down to 0 psi boost from 6.7 psi current boost.)

anyone? help me KA-T fellows

Post by **AZhitman** » Wed Sep 07, 2005 5:14 pm

Whoa whoa whoa!

Who asys stock injectors and ECU are only good for 3 psi?

Try 7-8.

Weld on a flange for an external wastegate, run a Tial with a 5 psi spring, and rock on.

(or am I oversimplifying this?)

Post by **Florida240sx** » Wed Sep 07, 2005 5:24 pm

AZ depends on where you live. Yes the stock ECU CAN handle 7lbs of boost but not in all climates. Fuirst night i tuned i was running rich.Next night I was lean. However I'm in the ever changing weather of Florida with humidity.

Post by **thekawaii** » Wed Sep 07, 2005 5:36 pm

okay let me give you the detail

KA24E SOHC turboI have T3 turbo from z31 with 6.7 psi setting.Internal wastegate with Log type mani.Fuelpump was upgraded to walbro 255 liter per hour,has Side mount intercooler with NO bov.Piping is just the ghetto HOMEDEPOT piping.Stock injectors and ECUSAFC II was wired in but useless cus i'm useless.

I filled up my tank with Shell V-power 91 gas. It ran 270 miles. Used to be around 350 miles. Means it actually uses more gas. (I drive very gently)

The car seems like it's overheating somehow. (not actually over heating but seems like) either it's just a manifold heat OR i might running lean.

So. when i installed my turbo, idle was good. The car actually ran very strong. Even new clutch couldn't handle after 2000 rpm with high throttle.Everything looked good. So i drove 300 miles with no problem.

But Many of NICO people told me that it will blow up. it will blow up. it WILL blow up. I don't know it yet because i never drove higher than 4k rpm. so i don't really know who's right.If you read my past posts, you'll find lots of people saying "no no"

So I need to tune my SAFC with 450cc injectors at shop. But until then, i want to drive safely with no boost. (about 5000 miles.)

That's what happen.

Post by **thekawaii** » Wed Sep 07, 2005 5:43 pm

oh yeah. I live in california. it's crazy hot here both day and night.

Post by **AZhitman** » Wed Sep 07, 2005 6:01 pm

I'll wait for the KA-t experts to chime in, but I don't see how you're gonna blow anything up.

IAP has been doing kits at 7 psi with nothing more than high-pressure / high-volume Walbro for a long time.

And CA don't know CRAP about heat.

"Seems" like it's overheating? You have a temp gauge? Where is it? Is your cooling system in good shape? Is it actually overheating or what?

If it's getting lower mpg, it's likely running rich, not lean.

Why the HELL would you put in 450cc injectors? There's NO WAY you need that size injector.

I think it's time to go back to the drawing board and quit changing parts.

Post by **virus77** » Wed Sep 07, 2005 6:08 pm

If you have an internal gate you can pretty much disable the boost alltogther. Take the swingarm on the wastegate flap and release it from the actuator, then just leave the wastegate flap in the all the way open position (mine was adjustable so I just adjusted it open all the way, im sure you can figure out a way to keep it open) this way the gate will amazingly take enought of the exhaust that the turbo barely boosts. I did this once on accident so thats how i know. I was pushing 2nd to redline and it would barely make a pound of boost.

Post by **thekawaii** » Wed Sep 07, 2005 6:11 pm

there's really no reason about 450cc injectors. i just got it when turbo came.

Cool, i didn't know about IAP kit. hm... i need wideband sensor.......

sigh another 300 bucks....

Anyway, thanks AZ. I trust you

Post by **AZhitman** » Wed Sep 07, 2005 6:53 pm

Why do you need a wideband now?

Stop spending money - you have what you need.

Sell the 450's, call Marc over at IAP, and I'll see if I can get you some more advice (more accurate than mine).

Post by **huguetpj** » Wed Sep 07, 2005 7:02 pm

I drove my car around boosting the hell out of it with stock injectors, and walbro 255HP @ 4PSI. Even got it to 9PSI on the dyno... but vey very lean conditions.

Just take it easy on the car while you figure out the problem.

Post by **Craving4Boost** » Thu Sep 08, 2005 12:14 am

kawaii you can use the safc to make the stock injectors to work harder...but i dont get why you just dont buy some 370cc injectors, throw them in and tune your car. but if your really that lazy just buy a 100$ fmu and throw it in and use the SAFC the tune it because it tends to run a little rich. cant believe you want to "turn off" boost after you just started

Post by **AZhitman** » Thu Sep 08, 2005 7:38 am

You DON'T need an SAFC.

You DON'T need an FMU.

You're only running 5-8 psi, you'll be fine.

Post by **Craving4Boost** » Thu Sep 08, 2005 8:09 am

AZ he already has an SAFC...and hes not an expert to turboing. also this is his first time so its not good to encourage him taking risk...he will get traumatized blowing his motor fast if its his first time

Post by **thekawaii** » Thu Sep 08, 2005 8:12 am

that's why i need wideband. dyno place charge me 150$/hr to find out AFR.

KA-T.org sticky said i need 450cc injectors, and i got it with turbo, so there's really no point why i got 450cc instead of 370cc.

FMU, i'm looking for one after brokeas240 told me to get it

Post by **Craving4Boost** » Thu Sep 08, 2005 8:13 am

300$ is a lot but its really worth...i really really recommend you getting one you will not regret it at all. once you get a wideband your future will look much easier

Post by **onosqv** » Thu Sep 08, 2005 8:53 am

thekawaii wrote:that's why i need wideband. dyno place charge me 150$/hr to find out AFR.

KA-T.org sticky said i need 450cc injectors, and i got it with turbo, so there's really no point why i got 450cc instead of 370cc.

FMU, i'm looking for one after brokeas240 told me to get it

hehe, I told u if you want to keep ur stock injectors, you may want to get a rising rate fpr, cuz safc is almost useless w/ stock injectors...

Basically, I've talked to thekawaii on IM, and this is I guess for ppl who are doing the same, a lil summary if you will (and +1 post count for me, yay whore).

First things first:

1) let's say 270cc can handle 7psi, shoot, say they can handle 8psi. His injectors are 15 or 16 years old, his turbo kit is used, etc, etc. Of course, we don't really know the situation of the 450's either, but at least that was the one included off the kit from a running car, haha.

2) let's take a situation of a boost spike to only 12psi (keep in mind his kit is USED) - w/ 270cc what happens? do I hear boom? what about w/ the 450cc?

Sure, it may be theoretically safe to drive around w/ the stock injectors w/ absolutely no tuning for a while in his car... he's trying to save money, but is he really going to save money if something DOES happen? why take the risk when you have the right equipment (i.e. 450cc & safc). I'm trying to convince him to bite the damn bullet & dyno that crap now w/ the 450's so he can be basically sure that he's good for low boost, rather than driving each day going "omg I hope I don't blow up".

My analogy for him was - say he could run 10mi/hr maxed out. Now he also has bike that he can ride @ 10mi/hr w/ half the effort, but he has to spend $10 to buy a pump for the tires since they are flat. Which situation would u rather be in for a marathon?

or

All of a sudden, there is a cop on his tail and he finds himself w/ a bag of weed and he goes 15mi/hr (beyond average human possibility aka 270cc???) - enter the boost spike. His legs will fall off or he will collapse, go to jail and become someone's g/f... or not. The bike should handle it better.

Would you rather ride the bike or save $10 & be someone's g/f?

Post by **onosqv** » Thu Sep 08, 2005 9:01 am

And because of the damn "can a virgin get pregnant" thread, I have a diff/better maybe analogy:

You're having sex (aka turbo)You have a condom (aka 450cc) but you don't know how to put it on & it's locked in a vending machine that's asking for 50 cents

You cccooouuulllddd have the possibility of not getting the girl pregnant w/o the condom (aka 270cc) or you could spend 50 cents and learn how to use the damn condom (450cc plus dyno & tune).

hrrrmmm, spend 50 cents... or the next 18 years raising a kid... not to mention the possibility of std's and all that nasty stuff.

and in case someone doesn't get my weird working mind...

Use a condom, put in the 450cc injectors.

Post by **virus77** » Thu Sep 08, 2005 9:21 am

whats all this crap about running 8 psi on stock injectors with no tuning or an FMU, thats retarded. I would feel unsafe running 8 psi with an fmu, either do it right or dont do it at all. Its gonna cost more to fix your blown motor than it is to get it running right the first time around. Dont skimp on a turbo cars fuel setup.

Post by **Craving4Boost** » Thu Sep 08, 2005 9:55 am

brokeas240sx - what about birth control pills

Post by **thekawaii** » Thu Sep 08, 2005 10:04 am

you guys are missing the pointi didn't mean "i'm gonna run 0 boost forever~?"Just temporary solution. Do i get hurt by running no boost? no. i think actually it's good idea to not build any boost since i made a mistake on researcing before i installed my turbo. I didn't ask you if i can run my car safely. AZ started that it's safe.I know stock injector will max out around 5~7psi, that's why i wrote "3psi" in safe range. dont you get it?OK who started this arguing?end of this thread.i'm gonna open my gate. period.

Post by **Craving4Boost** » Thu Sep 08, 2005 10:08 am

it will cause a major major exhaust leak and your turbo will hardly spool if your wastegate is alwyas left open.....how temporary is this?

Post by **thekawaii** » Thu Sep 08, 2005 10:11 am

YEAH! that's the point. if i only had stock exhaust piping, I'd go back to N/A setting. BUt i cut it. (said in very first sentense)

So before i have enough money to get either dyno or wideband, i need to not build any boost. so i don't blow up the engine.

I didn't ask if stock if stock injectors are good or bad, cuz i already know.

Post by **AZhitman** » Thu Sep 08, 2005 11:33 am

virus77 wrote:whats all this crap about running 8 psi on stock injectors with no tuning or an FMU, thats retarded.

Interesting, there's a lot of IAP Stage I cars running exactly that way.

Why use an FMU? It can fail just as easily as a Walbro with the stock FPR.

Post by **Import_Ant** » Thu Sep 08, 2005 12:33 pm

virus77 wrote:whats all this crap about running 8 psi on stock injectors with no tuning or an FMU, thats retarded.

I have been running that very setup since May. All I have installed is a Walbro 255lph fuel pump. My base timing is set to stock, I'm running a range colder plug but that is all. The way I drive this car (and with over 240,000 miles on the motor) if anything were to happen it would have happened by now. This of course is not a long-term setup, I just have some bills to pay off before I invest any more money in the car.

Post by **virus77** » Thu Sep 08, 2005 12:57 pm

So you guys just slap on the turbo and with no tuning let the MAFS just deal with the additional airflow and hope the stock injectors manage? Thats pretty cool if it works but I can imagine it would be amazingly lean, have any of you dynoed the cars or checked the A/F's during boost. Ive tuned my own car everytime with every setup change and it required quite a bit of additional fuel to get the car in the 12's afr on boost.

Post by **Import_Ant** » Thu Sep 08, 2005 1:02 pm

I should be able to confirm the AFR fairly soon. I haven't dynod the car but I should have a wideband within the next month or two and I'll post my readings through idle and in boost under WOT.

Normally I'd be more conservative but I have a spare motor sitting in the garage in the process of being rebuilt.

Post by **AZhitman** » Thu Sep 08, 2005 2:56 pm

Gotta remember, the 270's are only running at a fraction of their capacity in stock form.

And the ECU is capable of a VERY wide range of adjustment.

Post by **C-Kwik** » Thu Sep 08, 2005 7:09 pm

CC/Min. = Lbs./Hr. x 10.5

270 = Lbs/Hr x 10.5Lbs/Hr = 25.7

HP = ([INJECTOR SIZE (LB/HR) X DUTY CYCLE] / BSFC) X (# OF INJECTORS)

BSFC is typically about .55 for a turbo motor.

HP = ([25.7 x 1.00]) / .55) x 4

HP = 186

The HP difference ratio between a maxed out turbocharged 270CC injected KA is:

186 / 155 = 1.2

This figure will be fairly close to the pressure ratio needed.

A PR of 1.2 is 2.94 psi of boost. So, if you max out the injectors, you can safely run 3 psi. The KA tends to run a bit rich so there may ba a slight amount of wiggle room here. Beyond that, you are going to start getting lean very quickly.

By Contrast, a 370 CC injector is approximately 35 lbs/hr.

HP = ([35 x 1.00] / .55) x 4

HP = 280

Keep in mind that both figures are in engine HP. I won't post the calculation, but the NA KA runs at about 75% duty cycle. That doesn't leave you much of a cushion. All this said, I have hear of 4-5 psi KA's running around on stock injectors, but consider the environment changes. One extraordinarily hot day can lead to some ping and ultimately some very undesirable results. Hell, even a very cold day might have you overboosting slightly and toast the motor as well. Why chance it? Since you are running an internal gate, do as some suggested and rig the gate open until you can resolve your issues.

Post by **AZhitman** » Fri Sep 09, 2005 5:06 pm

How much impact does fuel pump have on that?

Post by **Nismo_Freak** » Fri Sep 09, 2005 5:20 pm

AZhitman wrote:How much impact does fuel pump have on that?

It tends to just raise the idle fuel pressure because the FPR can't physically regulate the pressure on some of the older cars. Once the engine starts to consume the fuel it will lower the "spike" pressure as the rail pressure increases.

Even so 3 - 5 PSI of rail pressure means d!ck in comparison to the amount of airflow he is covering.

Running stock injectors on a KA-T is MORONIC ... period.

I don't care if "it works", it's wrong and easily and CHEAPLY solved. So there is ZERO reason to be running such a hack job for a fuel system. I don't care if IAP is running that in their kits, they don't change physics, and it's less than ideal.

If you want real advice, keep those 450's. Put them on the car, and tune it, and run the full boost the w/g is regulating, which will make more power, reliably.

Okay, how can i kill my boost.

Okay, how can i kill my boost.

Re: (AZhitman)

Re: (thekawaii)

Re: (AZhitman)

Re: (AZhitman)

Re: (AZhitman)

Re: (Craving4Boost)

Re: (thekawaii)

Re: (thekawaii)

Re: Okay, how can i kill my boost. (thekawaii)

Re: Okay, how can i kill my boost. (brokeAs240sx)

Re: Okay, how can i kill my boost. (Craving4Boost)

Re: Okay, how can i kill my boost. (thekawaii)

Re: Okay, how can i kill my boost. (Craving4Boost)

Re: (virus77)

Re: (virus77)

Re: (virus77)

Re: Okay, how can i kill my boost. (thekawaii)

Re: (AZhitman)

Nissan Forums

Infiniti Forums

Datsun Forums

Technical Forums

Classifieds / Marketplace

Nissan Motorsports

General Forums