The Wankler

iTrader: (14)

I Have a friend that put one on his 87 T2. It also replaces the stock cat. How do I explain to him the ill effects of not have fuel/ or boost mgmt?

I had a friend do the same, and he blew his engine.

Thanks guys!
Chris

J-Rat

iTrader: (2)

Well, your friend should technically hit fuel cut before anything major happens, although fuel cut in itself is pretty damaging.

FYI I run that DP/MP and I LOVE it.

The Wankler

iTrader: (14)

Would runing the FCD Chip help?

J-Rat

iTrader: (2)

it will help prevent fuel cut, but if the fuel system isnt up to the task involving the boost creep that will probably happen with that DP/MP, then the motor is at increased risk.

The Wankler

iTrader: (14)

Ok, thank you. I will advise my friend it is not safe.

I imagine at the least, adding a MBC would help to prevent the high boost spikes?

J-Rat

iTrader: (2)

No, the MBC cant fight boost creep. The wastegate is being overwhelmed.

The Wankler

iTrader: (14)

ahhhhhhhh, great info. Thank you!,
Chris

Bukwild

I have one aswell. You really need to tell you friend to pull the turbo off and port the hell out of the wastegate. He might even try to use the honda valve thing. Also your friends next mod should be a standalone. If not his next mod will be a rebuild.

Dom_C

I wouldn't say to go as far as standalone. . He needs to work out the fuel system though. Bigger fuel pump, bigger injectors, and someway to control the injectors. While standalone is the 'Ideal' he does not need it. Alot of us are very happy with the Rtek chip, and others just use safc, or other piggy backs.

Bukwild

Kevin Landers loves this way of thinking. It actually keeps him in buisness!

alwayssideways

if he is running a stock turbo. he should be perfectly fine with a walbro, ported wastegate and some bigger injectiors.

I myself like bukwild stated have a bnr stage 2 35 mm ported wastegate, 720cc secondaries, rewire walbro, r-tek with a safc and boosting a solid 10 psi and im running safetly. Im very happy knowing i can take my setup even higher without really upgrading except bigger injectors .

adrock3217

I'd say go standalone or go home.

An R-Tek, SAFC2, boost controller, and all that other stupid stuff adds up to just about how much a standalone would cost, WITH LESS TUNING ABILITY. Or if you go Megasquirt 'n Spark..it's nearly double the price for the things listed above..

But yeah, standalone/wideband, fuel pump, fuel injectors, and gauges to moniter it all

Digi7ech

iTrader: (1)

Tell your friens that adding the downpipe makes the turbo spool quicker.
The Extra exhuast gases from the speedy spool then over spins the turbo.
The wastegate tries to ditch the extra gas to keep the boost in check(stock 6-8psi)

The wastegate get's overhwhelmed by the exhaust. It can't get rid of it quick enough. This makes the exhaust go through the only other way. Through the turbine which increases RPM and Boost.

The boost will then increase greatly over stock. The stock injectors are accepted to max out around 10-12psi.
So if he hits 10+psi he runs a VERY good chance of his fuel system not being able to supply enough fuel.


At a minimum I recommend to buy a Walbro fuel pump and rewire it's power lines.
Then get your fuel injectors cleaned. If they are dirty then throw out those max boost numbers because it's lower.
Then Rtek 1.5
THen port the wastegate and use a MBC to push it back up to 10psi.

If you want you can get some 720's and the upgrade Rtek.

Then in a perfect money is not a problem world. Get a stand alone. You CANNOT beat a stand alone.



BTW. I am currently running Walbro/Cleaned injectors/Rtek 1.5/ported wastegate/Aeromotive FPR set to 38psi with stepping 1psi per 1psi.
I'm set at 10psi but during this winter I've hit 12-13psi.Luckily the engine has lasted but I do not recommend getting near those numbers on 550's.

The Wankler

iTrader: (14)

Good advice, thank you, I am going to print this thread out and give it to him.
Chris

slpin

iTrader: (9)

.

J-Rat

iTrader: (2)

And the point with ^ would be?

NZConvertible

The point was you were wrong when you said...Plenty of people here have hit fuel cut many times (including me) and suffered no ill effects. It does not cause a lean mixture. It does not cause detontion.

J-Rat

iTrader: (2)

The fact is, if you ARE hitting fuel cut (and I have also hit it several times), and you want to continue to do it, thats your buisness. But if you are hitting it, then thats a sign of something gone wrong. Its not something I would chose to drive around doing, I would take care of it.

Another thing, if you trust that 18 or so year old ECU/Wiring harness/Injectors to perform fuel cut, when half of them arent even DELIVERING fuel correctly (not too mention leaky injectors, etc..) then you are putting your motor at risk. I will not drive my motor into a condition that contradicts EVERY TUNING TENET known to man.

Lastly, just because YOU said it can not be a damaging condition does not make it so. The only reason your statement was trotted out was because Slipn wants to make it look like I have no idea of what I am saying. Personal experience does not mean that someone has suffered detrimental effects of fuel cut. I dont care HOW many people have hit it, its not a safe condition to be running your motor in, in my opinion.

I stand by my statetment with one caveat; "Its a POTENTIALLY damaging condition, and needs to be corrected IMMEDIATELY"

gregk

If your friend has just a dp/mp, I would get fcd, bigger secondaries, and a boost gauge. Those would be essential. If he creeps past 10 psi...then port the wastegate and get a boost controller. All this upgraded fuel pump stuff and engine management is nice, but not necessary if you don't have the need and budget for it.

NZConvertible

In a completely stock car it's a sign something has failed and is causing boost to increase. In a modified car it's almost always due to increased airflow from intake and/or exhaust mods. It's not "something wrong", it's simply an warning that the manufacturer has decided this is the safe limit for boost and you should increase the fuel system capacity before you go further.

I agree that if you're hitting fuel cut you should do something about it, either by lowering boost or adding a FCD and appropriate fuel mods, if for no other reason that it's damn annoying.

I really can't see how this makes fuel cut dangerous. Performing fuel cut is simply not firing the rear rotor injectors. What exactly is going to prevent that from happening? And leaky injectors is irrelevant. The tiny amount of fuel in the chambers simply won't ignite. See my quote above.

Now you're just being over-dramatic. Fuel cut is used by most manufacturers to protect the engine from the effects of too much boost. Not to mention that just about every aftermarket ECU available has a configurable overboost fuel cut. Top-level traction control system rely entirely on fuel cut to work. Are you saying all the people involved in these products are completely wrong? I'll repeat what I've said before: It's silly to think that Mazda (and all the other car makers) would choose to protect the engine with something that might damage it.

This has been discussed at length before, and the fact is there is only one person on this forum who claims fuel cut damaged his engine. As much as I respect that person's knowledge and experience, there was an overwhelming number of people who make the same claim as me: no damage done.

Unless you can clearly explain what the "potential" effects are, this is simply a guess. Explain exactly how fuel cut can cause damage.

J-Rat

iTrader: (2)

Fine, no argument here...

Again, no argument here..

This is a statement that you cant prove.. It would depend on the level of leakage, and what residual fuel was left in the runners. Especially if the person was foolhardy enough to do this when the motor is cold, and more fuel is sticking to the sides of the runners.

Of course, and fuel/ignition, and ignition only, I am very aware of this considering I am on an E6K. Dont think being over-dramatic has anything to do with it.

Yep, but as previously stated, its not a system I would rely on after 18 years, given the FCs noteriety for poor electrical performance after this time.

I spoke at length with Rob from Pineapple at Sevenstock (which one I forget), and he informed me that he feels the system is laughable and dangerous. Given his experience, I dont take his thoughts on this lightly.

From the internet, so it MUST be true..!


Source: http://www.tekniqauto.com/US/tsport/tsport.htm


I still stand by my statement that fuel cut is an inherently unsafe condition to encounter on the FC.

Rat

NZConvertible

We're talking about an engine that's actually running, and almost certainly at medium-high revs. The amount of fuel that might enter the engine from leaking injectors is tiny. It would also be dribbling down the runner walls instead of being in a vapour, and not simply would not be able to be ignited. It's simple physics, and a complete non-issue.

Your statement that fuel cut "contradicts EVERY TUNING TENET known to man" is not only over-dramatic, but untrue. The fact that it's widely (and safely) used proves this.

You need to think about how the fuel cut actually works. It is controlled entirely within the ECU and has almost nothing to do with any external parts. The ECU simply decides whether or not to fire the injectors. The only input is the MAP sensor, and that only tells the ECU when fuel cut is required. Internal ECU problems are extremely rare, and usually result in something not happening when it should. Fuel cut is something not happening, i.e. injection. What exactly do you think is going to go wrong?

"Laughable and dangerous" is very vague and doesn't really say anything. If you haven't got his technical explanation to explain why he thinks this there's no point in even mentioning it. This system is considered safe by most major manufacturers and aftermarket EFI suppliers, so why should I trust Mr. Pineapple over them? He doesn't design and produce engines and EFI systems for a living; they do.

This is very misleading. Even if fuel cut did leave small amounts of fuel flowing through the engine (and exactly how would it?), small amounts of fuel do not randomly ignite. If there isn't enough fuel present to create a suitable air/fuel mixture it simply won't ignite. In the unlikely event it does ignite, small amounts of fuel only generate small amounts of heat. To be dangerous, you need a lean mixture that creates a lot of heat, i.e. a full-load lean mixture. It's the excess heat created that leads to detonation, not the lean mixture itself.

If you don't believe me, this is a quote from traction control systems maker Racelogic, who use fuel cut as the basis of their system:

"The idea of cutting fuel to an engine sets alarm bells ringing in engine builders, as they all know of the potential disaster of a high revving race engine running lean. Running in a lean combustion mode will elevate in-cylinder temperatures very rapidly, the denser the air/fuel charge, the more heat the lean burn can generate. Therefore it is vital that a fuel cut system will not cause a lean burn.

The simplest way of preventing a lean burn is to remove more than 50% of the fuel from the pulsed delivery. A mixture will only ignite if the air/fuel ratio is within a tightly defined window, look at the efforts being put into making lean burn engines fire on very low air/fuel ratios (1:20 or more). Removing more than 50% of the fuel will cause an air fuel ratio of over 1:25 and will result in a complete miss-fire, with the unburned fuel passing out through the exhaust valve. Even if a high air/fuel ratio did manage to ignite, the energy available from the amount of petrol injected wouldn't be enough to elevate temperatures significantly. Of course the ideal system will remove 100% of the pulsed fuel delivery, allowing the cylinder to take a gulp of fresh air, and the in-cylinder temperature would remain virtually unaffected.

Prolonged fuel cut on one particular cylinder would cause scavenging of the petrol lining the inlet tracts, and when the next full fuel pulse arrived, it would be partially reduced in quantity by the re-wetting of these tracts. Therefore it is often important to manage a rotation of the cylinder cutting to prevent this situation from occurring."

You'll notice to their two suggestions for safety are to cut fuel injection entirely, which is exactly what happens; and avoid prolonged fuel cut on one cylinder/chamber, which is simply lifting your foot off as soon as you feel fuel cut occur. This is the natural reaction anyway due to the fairly violent nature of fuel cut. Any idiot who keeps their foot down will eventually get what they deserve. The flat-shift system you linked to cannot rotate the cylinders as suggested, it can only cut all injectors.

But nothing you've put forward supports that statement. If it were inherently unsafe as you claim then there would be lots of posts on this and other forums telling of engines blown by fuel cut. But the fact is there aren't.

Do you really think that Mazda (and all the others) would protect the engine with something that you think will probably damage it?

J-Rat

iTrader: (2)

Or can be converted to vapor via heat, and yes, it is an issue.

Most systems today are fuel AND ignition cut.

Okay, that doesnt mean that the system designed for the FC was optimum. Just becasue there are tons of systems that can perform the same operation. This doesnt prove or disprove the inherent danger of running up on fuel cut in the FC. As of now this is more like a "he said, she said" type of argument. You keep bringing up the same points "Mazda would never do something to harm a motor" and "millions of EFI systems use it", okay great. That still doesnt steel my faith in 18 year old technology.

Also, I am vague about the conversation I had with Rob because it was probably over 3 years ago, and the details escape me. I just gave a synopsis of what was said, because of the "well I heard this, you heard that" nature of this discussion.

[quote]

This is very misleading. Even if fuel cut did leave small amounts of fuel flowing through the engine (and exactly how would it?), small amounts of fuel do not randomly ignite. If there isn't enough fuel present to create a suitable air/fuel mixture it simply won't ignite. In the unlikely event it does ignite, small amounts of fuel only generate small amounts of heat. To be dangerous, you need a lean mixture that creates a lot of heat, i.e. a full-load lean mixture. It's the excess heat created that leads to detonation, not the lean mixture itself.
Okay, you found a website that says fuel cut ISNT dangerous, and I found one that says it IS dangerous! So what exactly did that prove? And if you read the entire site, thier system is fuel and Ignition, depending on the situation. Given the modern nature of that system versus a first generation Bosch system, I would be more inclined to trust the accuracy of the modern system.

Thats probably because the vast majority of people that have encountered Fuel Cut have taken immediate steps to correct the problem. You seem to have some really misplaced faith of this forum as a vast pool of untapped knowledge. Most people dont even post what fixed or caused problems, so there is a distinct possibility that there are more people that suffered damage, but did not post up. That being said, the premise of forum experience is hardly what I would consider the cornerstone of a solid defence of your position.

Its possible they went with the least expensive option to save money. So, again, I am not convinced. Now we have conflicting websites and information. Your arguments havent changed, and neither have mine.

WhyteOut

Im The Wanklers friend thats running the thunder fab. downpipe. i appriciate all of the info. i believe i will be taking that off real soon to prevent any kinda damage. lol. Chris, thanks for starting this thread. i really appriciate it.
-Seth

WhyteOut

also, boost has never crept over 8 psi in my car.. no matter how hard i push it