[kafn8ed]

I was wondering how much boost we can run before worrying about detonation? On a stock bottom end without water injection or anything crazy? I've been thinking about the Hotshot T3 kit for a while. I know it comes with a .4 bar wastegate spring, but I was wondering if it could be pushed much further (on occasion). If not, I won't have to budget for a boost controller. If so, any reccomendations for a good one. I was kinda thinking Apex'i AVC-D. Looks inexpensive, but easy to use.
thanx,
Jason

 

[PSSSHHHGOESMYSR20]

Depends on your how much your injector flow is, considering what size injectors you are going to be using. I boosted 13 pounds on a t3t04e turbo with 370cc injectors with no detonation. The Hotshots comes with a .4 bar spring thats like 6 pounds not much at all you wouldnt have to worry about it, If you want a boost controller to go with the kit, I would suggest the Blitz SBC or HKS EVC ez or maybe a manual boost controller, I would stay away from the Fuzzy logic controller cause they are a PIA

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http://geocities.com/yellow4g63/sr20det.htm

Mike.
Turbo Classic, T3/T04e Tial 35mm ".65Bar" Blitz BOV, Custom piping griffen intercooler Core with HK$ EndTanks,custom manifold, 370cc injectors, paxton fpr, Eibach Sportlines, everything else was stolen, Speedpro coming soon bigger Injectors and custom fuel rail. Equal length stainless steel manifold. Fortified Tranny. DAMN VILLIANS.

 

[Zak91SER]

Tom Paule had the Hotshot kit on his SE-R for a while running at 10 psi. It was pushing the limits of the MAF and injectors, but it didn't detonate for the most part.

 

[SucKit]

Is detonation audible at WOT? What does it exacly sound like? cause i ran 15psi with the stock pump and i dont think ive ever heard it b4.

 

[IMOA]

I'm looking forward to someone trying to explain what injector flow has to do with detonation.

In the end you can run as much boost as you want, you'll just start losing power when the tradeoff in timing costs more than what the boost can give. For the boost controller if you're on a budget then I'd bypass the electronic boost controllers and go for a decent bleeder. Don't go too cheap with one that bleeds all the time but grab one of the later models which are designed to bleed only when the preset boost level is reached.

Bad detonation can be heard at WOT but mild - medium detonation can be a little difficult to hear. It will sound like someone shaking a glass jar with a few ball bearings in it, quite high pitched and metalic "tink, tink, tink"

 

[Scarpa]

I'm not too sure about this but a bigger injector means you can dump more fuel into the mixture to cool things down. A poor man's water injection.

 

[kafn8ed]

I was looking at the Apex'i AVC type D since it's the lower cost and simpler version. Later I plan to do some headwork, cams, possibly lower compression, bigger injectors, and so on. If I get a higher capacity fuel pump and injectors, when does compression start limiting boost? What other factors can or will cause problems?
Jason

 

[spdracerUT]

Not a big enough injector.... can't flow enough gas.. run lean... get detonation... **** blows up

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'96 SE-R.... a few tweaks here and there

 

[Zak91SER]

Yes, you should be able to hear detonation. It will sound sort of like a high pitched metallic jangling noise, and it won't be all that loud so you'll have to listen for it. If you hear it, IMMEDIATELY get off the gas and turn your boost down, or stop getting into the boost altogether if you can't turn it down right away.

And you don't use bigger injectors just to flow more fuel to cool things down... you use bigger injectors because the fuel flow rate needs to be able to keep up with the spark and the whole combustion process which is greatly accelerated when you add a turbo or any other kind of FI. If you don't run bigger injectors you start running lean, then you start detonating, then your motor explodes. It's not really comparable to water injection, which really is just a safeguard, or a bigger safety margin.

 

[Scarpa]

<font face="Verdana, Arial" size="2">And you don't use bigger injectors just to flow more fuel to cool things down... you use bigger injectors because the fuel flow rate needs to be able to keep up with the spark and the whole combustion process which is greatly accelerated when you add a turbo or any other kind of FI.</font>

I know that stock injectors won't flow enough to keep from running lean, but I thought some people ran way oversize injectors so that they could dump fuel as well. I assumed that is what Mike C. meant as I'm pretty sure that was his argument against water injection awhile back when he was arguing with Jay. Maybe I read it wrong. I don't have a turbo, and don't plan on getting a turbo so my opinion is about as valuable as a monkey's.

 

[IMOA]

Running lean does not cause detonation, it causes running lean, something completely different. Detonation is an uncontrolled burn, running lean means that combustion is incomplete so it starts trying to combust anything else about like your pistons and valves. Bigger injectors are certainly needed the bigger you go with the turbo as it will require more fuel but it has nothing to do with detonation.

Detonation is caused by:

Boost - more boost detonation more likely
Heat - more heat detonation more likely
Timing - more timing advance detonation more likely
Load - more load detonation more likely
Revs - lower revs detonation more likely
Fuel - lower octane detonation more likely

 

[Zak91SER]

I'm running the 72 lb. injectors, for example, because the 50 lb injectors would be maxing out at the HP level we think we can get with my car. It's not for "extra fuel" per se, because the A/F mixture is controlled entirely by the ECU... it's not going to start running rich unless it's programmed that way, regardless of injector size.

As far as Mike C is concerned, in his case that could be why he did it, because he believes in tuning his own car with a standalone. He could program the injectors to deliver more fuel than is necessary to complete combustion if he wants to. In my case, I have a JWT ECU that's programmed specifically for the 72 lb. injectors, for performance, not extra fuel.

But running rich is a performance penalty, you get more performance the leaner you run. Water injection is not comparable, because water injection simply cools the intake charge before it goes into the motor. To be general about it, it serves the same function as an intercooler. If you have an intercooler already, water injection serves to further cool your intake charge, allowing you to run more boost without detonating. Dense air = more power.

<font face="Verdana, Arial" size="2">Running lean does not cause detonation, it causes running lean, something completely different. </font>

Yep. Either one can kill your motor. That's a good point about load, too... don't assume you're only going to hear detonation at high RPMs... it's actually more likely to happen at lower RPMs going up a hill for example.

When detonation occurs, it takes a certain temperature range for it to happen. By cooling your intake charge as much as possible, you can prevent detonation by starting off with a lower air temperature as combustion begins. The reason lower compression helps (i.e. 8.5:1 instead of the stock 9.5:1) is because the act of compressing the air heats it up. Lower compression ratio, less heat.

So you can see why adding more fuel is not the same thing as water injection at all. That's why I think water injection is a better solution than just dumping more fuel in, because with water injection, you can keep an optimized A/F mixture while lowering the in-cylinder temperature. Adding more fuel just makes you run rich, which hurts performance. It does help prevent detonation, but it also affects performance negatively.

 

[Thomas Reynolds]

<font face="Verdana, Arial" size="2">Originally posted by IMOA:
Running lean does not cause detonation, it causes running lean, something completely different. Detonation is an uncontrolled burn, running lean means that combustion is incomplete so it starts trying to combust anything else about like your pistons and valves. Bigger injectors are certainly needed the bigger you go with the turbo as it will require more fuel but it has nothing to do with detonation.

Detonation is caused by:

Boost - more boost detonation more likely
Heat - more heat detonation more likely
Timing - more timing advance detonation more likely
Load - more load detonation more likely
Revs - lower revs detonation more likely
Fuel - lower octane detonation more likely</font>

What?!? What do you think lean means? It's not something completely different. It means that you have way more air that you need for the given amount of fuel in the combustion cycle. What does this cause? H-E-A-T. You just threw a bottle of oxygen in that small fire.

A lean running condition will promote detonation, because a lesser quantity of fuel, when vaporized, will absorb less heat. Thus a lean mixture increases heat, the root cause of detonation.

Detonation:
Running Lean = Yes
Low Octane = Yes
Revs = huh? No.
Timing = Yes
Exhaust Back Pressure = Yes

 

[SucKit]

Zak does JWT have different programs for performance? Cause both ECU's that ive used seem to have completely different programs...both have the same program code but are different in which how they perform, one idles great and the other idles from 700-1100k like it has cams, and also overall driveability issues... but both are consistent in running rich tho.

As far as detonation, how fast can it kill an engine? I modified my fuel delivery anywhere from -8 to -20 percent on the ecu for the past 9 months, when i punch the throttle the a/f voltage reaches a steady .93 but im worried since im not really familiar with what i thought detonation sounded like and that its slowly killing my engine...any thoughts or suggestions would help cause i still have that bog that i attribute to running rich or timing being pulled but im not so sure anymore.

[This message has been edited by SucKit (edited 09-20-2001).]

 

[kafn8ed]

Thanks guys. This is a good discussion. Informative. Basically what I'm getting is if I get a controller, be careful. 10 psi seems a good limit for now since I'll have to relearn the car a bit. Later I plan to do more engine-wise, but once I get the turbo on I think the best move would be suspension and brakes. I'd like to stick with something simple but effective in a Boost Controller. Any suggestions?
Jason

 

[IMOA]

Thomas - Detonation is completely different. Detonation occurs when the end gasses spontaneously ignite and explode in an uncontrolled manner. The flamefront from the spark moves at around the speed of sound but the uncontrolled burn moves at many times that. It batters the pistons, cylinder walls etc chipping away at them, this is the pinging sound you hear. Running lean means that there's a fire in there but it's run out of fuel therefore it uses your pistons, valves etc as that fuel. They are completely different things.

"Revs = huh? No." - at lower revs the air/fuel mix is in the cylinder longer therefore has more time to selfignite. Assuming all other factors are the same you are more likely to detonate at lower revs.

 

[Zak91SER]

This is a good discussion.

SucKit, JWT has a number of different programs. I don't know which ones you have though. If your two prgrams are acting differently they're probably different programs. I'd give JWT a call and just ask them about it.

It will take a while for detonation to kill an engine. The effect of detonation is that you get these little shockwaves of super high pressure hitting parts like your pistons and head. The pressure is so high and moving so fast that the "ting ting ting" sound that it makes is literally the shockwave itself ramming itself into your pistons and head. Think about how hard it would have to be hitting the pistons in order to make a sound so loud you can hear it from inside the cabin. Detonation can wear away your head and ring lands. Every "hit" from a detonation shock wave can literally put a small hole into something in your engine, it's that strong.

That's why it's important to IMMEDIATELY get off the gas if you hear detonation, and turn down the boost or stay off the gas.

Now actually getting small holes in your pistons is a worst case scenario, If you detonate a little bit I doubt it will do very much. But it's something that you'll need to take care of because continuing detonation will most likely start damaging parts. You can take care of detonation by doing one of things already listed, such as -

higher octane
lower compression
less boost
lower intake air temp (i.e. adding water injection)
retard your timing
less backpressure (bigger exhaust system)
higher RPMs (this should work if you're borderline detonating).

And if you can't hear detonation then you're probably not detonating. It may be worth your time to find a hill, and go up in 5th gear at a lower RPM and listen carefully for detonation. It should sound like a high pitched metallic "tinging" or jangling. You will know it when you hear it, because you'll know the engine doesn't sound like that normally. If you can't hear anything, then most likely you're not detonating.

kafn8ed, I recommend the profec B boost controller, seen here along with the greddy turbo timer:

And then in this pic, see my blowoff valve, with the purple cover? hard to miss it, I know. But just to the right of it is a black box mounted to the strut tower - that's the controller box for the Profec-B. It's a pretty easy install, relatively.

And of course I definitely agreee with you about the suspension and brakes... they are absolutely necessary. You will have to brake so much harder and faster than you're used to, because the same amount of effort that it took to get the car to 60 MPH will now get it to 90 MPH, and it's hard to adjust to for a little while.

 

[Thomas Reynolds]

<font face="Verdana, Arial" size="2">Originally posted by IMOA:
Thomas - Detonation is completely different. Detonation occurs when the end gasses spontaneously ignite and explode in an uncontrolled manner. They are completely different things.</font>

Yes they are completely different but the discussion was what *causes* detonation in which you stated it does not.

Is octane rating and detonation the same? No.
Is revs and detonation the same? No.
Is backpressure and detonation the same? No.
Etc, etc, etc.

This was about the cause of detonation and running lean *is* a cause.

 

[Geo]

<font face="Verdana, Arial" size="2">Originally posted by IMOA:
Thomas - Detonation is completely different. Detonation occurs when the end gasses spontaneously ignite and explode in an uncontrolled manner. </font>

Running lean can indeed cause detonation. What happens is when running lean, the temps in the cylinder and combustion chamber increase. If things get hot enough (usually on the edge of something such as a valve or the combustion chamber), it will ignite the fuel/air mixture before it is supposed to light off......

Detonation.

 

[kafn8ed]

Hey guys,
Thanks for all the advice. Unfortunately, the finances for this project just went away.

It's a long story. Let's just say some of my past caught up with me. I'm still looking to do this later (maybe spring), but it's postponed for now. When things change, I'll start this back up. Until then...
Jason