Safe boost levels for KA-T w/ stock fuel delivery

Post by **wannawangan** » Tue Jun 28, 2005 8:51 am

What level of boost is considered safe using the stock KA24DE 270cc injectors?

HP GOAL = 225 rwhp (if possible)

I'm looking to go KA-T w/ low boost until I can afford a fuel delivery computer (i.e. SAFC, eManage, etc.)

I've looked at the reference table under the stickie titled Injector Spread Sheet. Based on the table, a little under 189HP seems to be possible.

Post by **Florida240sx** » Tue Jun 28, 2005 8:57 am

Not possible unless using FMU. Also aren't our stockers 260cc? For $100 you can get SR 370cc injectors.Always someone selling.Play it safe and get better injectors.

Post by **214kka-et240sx** » Tue Jun 28, 2005 8:57 am

depends on turbo too,but you can make like 220 hp on like a t25 with stock injectors. but if you have bigger turbo, not safe to have stock injectors

Post by **Florida240sx** » Tue Jun 28, 2005 8:59 am

Although with the IAP kit they were makinf like 230rwhp with stockers I beleive...Although I think they had FMU for those setups...

Post by **wannawangan** » Tue Jun 28, 2005 9:13 am

heh heh, you guys posted responses before I can finalize my edited post

By the way, what is the difference between an FMU and a boost-sensitive FPR? From what I understand, and correct me if I am wrong, an FMU provides a constant amount of fuel pressure based on a defined static setting (twist of a screw + gauge reading) whereas the boost-sensitive FPR adjusts fuel pressure as a function of boost based on vacuum pressure from the intake manifold. I am trying to figure out what would best suit this low boost configuration.

I have considered using a boost-sensitive FPR assuming boost levels of 4-6 psi, accompanied with a MBC for overboost protection as well as a Walboro fuel pump to keep fuel pressure constant.

Post by **wannawangan** » Tue Jun 28, 2005 9:17 am

Looking at a T25/T28 or an SR T25, for starters.

Post by **Craving4Boost** » Tue Jun 28, 2005 9:29 am

i think you got your units backwards....

FMU increases fuel pressure depending on how much you are boosting...also depending on what size disk you use...

for example 8:1 disk...you will increase 8lbs of fuel pressure for every lbs of boost.

please search because this has been talked about

Post by **Nismo_Freak** » Tue Jun 28, 2005 9:41 am

An FPR provides a 1:1 ratio gain, it is linear.

A RRR (Rising Rate Regulator aka FMU) has a much faster linear gain with the rate depending on the gain ratio.

Arbitrary numbers:

10 PSI on stock FPR - 43 PSI + 10 PSI - 53 PSI10 PSI on a 4:1 RRR - 43 PSI + 40 PSI - 83 PSI

I am not 100% sure if the RRR tends to increase fuel pressure when vacuum is lessened. If that were the case then you would be running well over 100 PSI of fuel pressure and that is not good for your injectors. You are inviting engine failure.

I would save your money and invest in a proper setup.

Post by **Florida240sx** » Tue Jun 28, 2005 10:07 am

I say SAFC and sr injectors.Cost you about 350. Marty at injected will give you a good deal.Injectors jsut make a post in classifieds.Also can buy used safc and save more $$$

Post by **hannibal** » Tue Jun 28, 2005 11:21 am

As Nismo said, a FMU and rising rate (fuel pressure) regulator are the same thing. You definitely need an FMU if you want to turbo and use your stock injectors. Those horsepower limits in the sticky are based on 80% duty cycle and stock fuel pressure. The FMU will allow you to flow more fuel through those stock injectors (becuase of the higher pressure).

It doesnt matter which turbo youre running. If it flows xxx amount of air (enough for 225whp), you will need xxx amount of fuel to be safe (safe = avoid running lean).

PJ from BoostDesigns says he made 232whp with an FMU setup. That seems to agree with IAP's claims for their kit.

Post by **hysteria** » Tue Jun 28, 2005 11:37 am

doesn't matter whether you use a 12:1 or 8:1 fmu you will reach a peak fuel pressure as determined by the capacity of the fuel pump. this is why 8 psi of boost is the reccommended highest boost because any more than this and the walbro pump that is so often used as a replacement to use with rrfpr's max's out and then the car just starts to lean out after 8 psi of boost. the difference between the 8:1 and the 12:1 will be that the 12:1 will max out sooner than the 8:1. this just means that whenever you're not running full boost, which would put both rrfpr's at the same fuel pressure (~the max of the pump's pressure capacity), you will just be richer with the 12:1 because it has a more aggressive increase in pressure. so no matter what rrfpr/fmu you use your max pressure will not be higher or lower, and thus the point at which your engine will start to lean out will be the same in either case, you'll just get worse gas mileage with the 12:1.

Post by **Jookmasta** » Tue Jun 28, 2005 12:37 pm

as said before, just save up more money and get a proper setup. 370cc injectors and an SAFC will get you to that power goal VERY easily. $350 is the normal cost, but remember that you will need a new upgraded fuel pump.

Post by **koenig** » Tue Jun 28, 2005 3:46 pm

The IAP kit it comes with the FMU or the Walbro fuel pump. Which is better for using stock injectors? I only plan on running 7-8 psi max as a daily driver but as you all know you can never have enough power!!! So i might upgrade later.

Post by **Florida240sx** » Tue Jun 28, 2005 4:18 pm

Get both...They were using FMU I'm sure and you'll want an upgraded fuel pump to be sure it's gettign enough fuel. Ask them about their setup if they ran both...

Post by **wannawangan** » Tue Jun 28, 2005 4:21 pm

Florida240sx wrote:Also aren't our stockers 260cc?

That is correct. Had to reference the stickie.

Post by **koenig** » Tue Jun 28, 2005 4:25 pm

So do u guys think its safe to run 7-8 psi with only upgraded fuel pump? I will eventually upgrade the fuel system later but funds are short right now.

Post by **wannawangan** » Tue Jun 28, 2005 4:26 pm

Site appears to be down. Will check back later.

Checked site @ 7:25p PST

Post by **wannawangan** » Tue Jun 28, 2005 4:43 pm

Based on the responses, it seems that an FMU and upgraded fuel pump are necessary to boost up to 8 psi (max) on a stock KA24DE.

Post by **Nismo_Freak** » Tue Jun 28, 2005 9:34 pm

koenig wrote:So do u guys think its safe to run 7-8 psi with only upgraded fuel pump? I will eventually upgrade the fuel system later but funds are short right now.

Imagine how short they will be if you blow your motor.

Save up the money, buy the correct setup.

Impatience just leads to stupid decisions.

Post by **TheOne** » Tue Jun 28, 2005 9:43 pm

i though IAP was doing that with stock injectors, and that the stock FPR will give the needed fuel for 7 psi with the upgraded pump.(i believe i read this from the price and availability of iap kit thread), they(not gofast1 which is from isp, but others, on 2nd page) also said that it was actually runnin a bit rich on the side.

(i may be wrong or just understood the post the wrong way on that thread, so don't 100% count on this)

Post by **Nismo_Freak** » Wed Jun 29, 2005 1:17 am

TheOne™ wrote:i though IAP was doing that with stock injectors

When larger injectors are readily available for around $100 a set, and a S-AFC to run them can be had new for a little more than $200 I do not see any reason to run stock fuel injectors.

Post by **WDRacing** » Wed Jun 29, 2005 5:32 am

A FMU is a must with stock injectors...no need to debate that point at all. It's simply unsafe to run boost on a stock set of injectors with no FMU.

Although a FMU and 8 lbs of boost is a very good way to get those extra horses out of the KA-T.

Personally I'm with Nismo, buy a set of injectors and get a SAFCII.

Post by **:: orion ::** » Wed Jun 29, 2005 6:11 am

^^^ Exactly.

To make it very clear, b/c this thread got a little muddy somewhere...

For a KA-T with:

Stock Injectors ONLY: DO NOT BOOST at all.

Stock injectors (270cc, BTW) + FMU: Safe limit of 8psi

370cc SR20 injectors + S-AFC: Safe limit of ~240rwhp (7-8psi from a T3/T4)

...

- Brian

Post by **wannawangan** » Wed Jun 29, 2005 6:57 am

Thank you for clearing up the mud.

BTW, what kind of HP levels can I expect from the 270cc + FMU set up w/ 8psi ?

Post by **hannibal** » Wed Jun 29, 2005 7:01 am

Just a little less than the SAFC + 370c combo. I guess about 230whp from a T3/T4. And thats what BoostDesigns and IAP made with similar setups...

Post by **hysteria** » Wed Jun 29, 2005 11:48 am

numbers don't mean much when you don't have a concept of what kind of power you're dealing with... i have no idea of your past experiences wannawangan, but for me to really know the power and feel of a car i have to drive it. case in point: one of my friends has an twin turbo rx7, and another friend has an sti. number wise the sti has the rx7 beat (hp wise, quarter mile wise, etc) but when you drive the two cars it is QUITE clear which one is a power house race machine... the rx7. i've driven both and i don't care what the numbers say, the rx7 has it beat in every aspect... of course they are different layout and all but i'm just using this as an example where numbers don't really tell the truth. if you pitted the rx7 against the sti in anything other than a straight line race from a dead stop i'm confident the rx7 would win.anyhow so i guess what i'm getting at is that for me numbers mean next to nothing... it's all about the feel of the car, potential, driveability...basically what all that power feels like when it's behind you. i can tell you first hand that a 8 lb setup with an fmu on a ka is a VERY significant gain, and it feels awesome. i have no idea how much power my car makes but i'm quite positive it is at the very least 50% more than stock... it feels great, and will feel even better as i upgrade. i think just about anyone else around here will tell you the same. the ka is a very surprising engine... i had an idea of what the outcome was going to be like when i got into this, but i have to tell you that it surpassed my expectations with the way it pulls and drives and everything... this engine is loads of fun.

Post by **WDRacing** » Wed Jun 29, 2005 1:12 pm

You know whats cool about guys who type without using grammar....NOTHING.

Numbers mean everything when your comparing two different setups for fuel managment. Feel and drive have nothing to do with it.

Ever take an STi out on a road course? If the RX-7 beats it, you need a new driver behind the wheel of the STi. Hell, the STi isn't even known for the 1/4, it's known for it's rally bred handling on the track.

Post by **koenig** » Wed Jun 29, 2005 1:32 pm

But if i go the 370 and afc2 then i also have to get the wideband. That then gets expensive. So what do u guys theink is better then afc with wideband and some sort of timing control or a ecu tune? i know with the ecu tune there is no chance to do extra tuning but then there are less potential problems..... Good thing i have a couple months to think about it.

Checkered-Member · Post by **Checkered-Member** » Wed Jun 29, 2005 2:32 pm

koenig wrote:But if i go the 370 and afc2 then i also have to get the wideband. That then gets expensive. So what do u guys theink is better then afc with wideband and some sort of timing control or a ecu tune? i know with the ecu tune there is no chance to do extra tuning but then there are less potential problems..... Good thing i have a couple months to think about it.

Not necessarily

The reason you should only run 7 psi (i say 6) with the SAFC is because the SAFC is a less precise tuning tool, so if the piggy back makes a mistake at 7 psi, the worst that can happen is that it will ping a bit you would hear it and let off and fix the problem, if same problem occurs at 12 psi, you will put a hole in the block, so you have more margin of error with less and less boost

With a more precise tuning tool like the e-mange you can run more boost, with a stand alone I have seen 15psi on stock internals.

A wide band will provide you with more tools to run higher boost.

The better/more engine management tools you have the more boost you can run safely

Post by **Import_Ant** » Wed Jun 29, 2005 2:46 pm

:: orion :: wrote:
For a KA-T with:

Stock Injectors ONLY: DO NOT BOOST at all.

I am unsure if you are accounting for the fact that upgrading your fuel pump WILL increase your base fuel pressure. that increase should remain static as mentioned before, the stock FPR is a 1:1 rrfpr.

I agree it is unsafe to boost without ANY fuel mods, I am boosting fine on stock injectors and Walboro 255lph fuel pump however.

currently I'm sticking to half a bar (7.35 psig) of boost and have been doing so for almost 3,000 miles with no problems. According to IAP the Walboro they sell w/ their kit is supposed to raise fuel pressure by 6-8 psi.

*disclaimer* I do have a 90' 240 w/ stock SOHC motor which means I am running 8.6:1 compression. */disclaimer*

Safe boost levels for KA-T w/ stock fuel delivery

Safe boost levels for KA-T w/ stock fuel delivery

Re: Safe boost levels for KA-T w/ stock fuel delivery (wannawangan)

Boosting w/ Stock Fuel Delivery

In response to 214kka-et240sx:

Re: Boosting w/ Stock Fuel Delivery (wannawangan)

Re: (Florida240sx) - KA24DE Fuel Injectors 260cc

Re: (Florida240sx) - InjectedPerformance.com - Site down

Re: (koenig) - Basic Fuel Set Up

Re: (koenig)

Re: (TheOne™)

Re: (:: orion ::)

Re: (hysteria)

Re: (koenig)

Re: (:: orion ::)

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