How bad is turbo without intercooler?

[qoncept]

Originally Posted by AVOturboworld

If the engine is already running hot in n/a form, especially at the track, then adding power is only going to increase that heat. The heat is, in the main, generated in the combustion chamber - and your oil and water cooling system is there to lower that temperature as much as possible. Running without an intercooler will raise those combustion chamber temperatures even higher. Knock and detonation will increase exponentially.

What I'm saying is that the situation is complex. If your engine was already at the limits of the standard cooling system, adding boost without cooling the charge temperature will tax it beyond the cooling capacity of the system. What's the point of adding a FI system if you could only run 1psi of boost?
...
Motors overhead in racing because the longer you stay at extended rpm's, the more heat in the engine that the cooling system has to deal with. 95% of street (OEM) systems are designed for occasional high-rpm usage, and can (and usually do) start failing when used constantly at high rpm's.

Adding boost - hot, compressed air - is doing similar things as running at higher rpm's. All FI systems are equal in this regard. Intercoolers are there to help alleviate that fact. Given that the discussion is about non-intercooled FI, it's even more relevant on how long you remain in boost. Intercoolers are not the only component in the engine that become heat soaked.

I conceded that the car needs a bigger radiator for increased output. But, like I said, it has nothing to do with an intercooler. Overheating is caused by insufficient engine cooling, NOT by insufficient intake charge cooling. Heat in an engine is mainly a product of friction, not combustion. And properly tuned, your EGTs (and therefore heat from combustion) CAN'T be any higher or you're going to be burning valves.

Seriously? You make it sound like you could tune the car to run boost on 87 octane, and the stock motor isn't even barely capable of that. That's because you can only do so much ignition retard before your EGT's get too high and start melting other components. So, yes, octane levels *are* some magical threshold.

Uh.. Yeah, I'm serious. You could tune the engine to run on 87. It's in the pumps we all get gas from, manufacturers know that, and dumbasses put it in cars that say "premium only" all the time. Somehow their engines don't blow up. But if I'm wrong, tell me - where is the magical octane threshold that it's impossible to tune our engines for?

The other problem in that statement is that it ignores what happens when you drive cross-country.

Our ECUs are pretty advanced and there are compensations for everything we can think of and more. They are of course factory tuned and not even getting touched, but they're better than anything a "professional tuner" could come up with anyway. You know, the millions of dollars of R&D that went in to it vs a couple hours on a dyno with a "professional tuner." Put a bigger radiator or an oil cooler on your car and it's not as incredibly high strung as you suggest. It's a Subaru engine, not a Ferrari.

You have "should do" and "can do" totally confused. Do me a favor and figure out which is which before you reply. I haven't said anyone should do a turbo without an intercooler, and in fact said otherwise. I wouldn't ever bother turbocharging a high compression engine on stock internals period.

[AVOturboworld]

Originally Posted by qoncept

I conceded that the car needs a bigger radiator for increased output. But, like I said, it has nothing to do with an intercooler. Overheating is caused by insufficient engine cooling, NOT by insufficient intake charge cooling. Heat in an engine is mainly a product of friction, not combustion. And properly tuned, your EGTs (and therefore heat from combustion) CAN'T be any higher or you're going to be burning valves.

Really. So it's friction in the engine, not the 4500° in-cylinder temperatures, that's the main source of heat and the main need for cooling systems.

Look, I'm all for discussions, but by your theory, engine temperatures would not go up at all when increasing the power in an engine, because the *friction* would be the same. Right?

Uh.. Yeah, I'm serious. You could tune the engine to run on 87. It's in the pumps we all get gas from, manufacturers know that, and dumbasses put it in cars that say "premium only" all the time. Somehow their engines don't blow up. But if I'm wrong, tell me - where is the magical octane threshold that it's impossible to tune our engines for?

In N/A form, the engine won't blow up on 87. But we are talking FI, right?
And even in N/A form, there is a certain level the ECU can retard timing to - and then it stops. If you exceed that level, you are out of luck.

Our ECUs are pretty advanced and there are compensations for everything we can think of and more. They are of course factory tuned and not even getting touched, but they're better than anything a "professional tuner" could come up with anyway. You know, the millions of dollars of R&D that went in to it vs a couple hours on a dyno with a "professional tuner." Put a bigger radiator or an oil cooler on your car and it's not as incredibly high strung as you suggest. It's a Subaru engine, not a Ferrari.

To a degree, you are correct. But we've tested said ECU and motor with FI for over 10,000 miles, from sea level and moderate temperatures to 6000 feet and freezing temperatures, to Nevada desert at 115°+. And yes, there are limitations to what that ECU can compensate for. Tuning it to run on 87 octane, boosted to any significant pressure in the Nevada desert is outside of what it can do. And that's with an intercooler. If you think we are wrong, you are welcome to FI your car to 5~8psi, tune it yourself to run on 87 octane, and run it in the Nevada desert with your foot on the floor to prove us wrong.

[deucethemoose]

Excuse me while I squeeze a seat in here.

[qoncept]

Originally Posted by AVOturboworld

Really. So it's friction in the engine, not the 4500° in-cylinder temperatures, that's the main source of heat and the main need for cooling systems.

Look, I'm all for discussions, but by your theory, engine temperatures would not go up at all when increasing the power in an engine, because the *friction* would be the same. Right?

I'm all for discussion, too, but you conveniently gloss over or ignore almost exactly half of everything I say so it's pointless.

But to answer your questions:
1) Yes, it's friction in the engine, not the 4500° in-cylinder temperatures, that's the main source of heat.

1.5 Extra Bonus!) In-cylinder temperatures won't be any higher when properly tuned. See: my previous post

2) No, "most" and "all" are not the same thing. ("but by your theory, engine temperatures would not go up at all when increasing the power in an engine, because the *friction* would be the same. Right?")

If you think we are wrong, you are welcome to FI your car to 5~8psi, tune it yourself to run on 87 octane, and run it in the Nevada desert with your foot on the floor to prove us wrong.

See: my previous posts

I'm not turbocharging a 12.5:1 compression, I'm not doing it on stock internals, I'm not doing it without an intercooler and I'm not running 87 octane. But you can be sure that any time I am in the market for parts, I'll talk to and ultimately buy from someone who can listen to what I'm saying.

[buditjoenawan]

Wow! Interesting back and forth! I'm trying wrap my head around all of it and digest.

So qoncept, your position is that an intercooler *is not* needed? And that octane ratings *does not* matter? I'm rather confused at both these assertions really. Since decades of internal combustion engine development flies in the face of the above 2 statements. I VERY well could be misreading what you're written, or misunderstanding your intentions. Please correct me if that is the case.

Regarding heat in the engine vs in the engine bay: when you compress air, you heat the air up. The more you compress it, the more heat you introduce. Can we agree on this basic law of physics? If we can, then the intercooler's (or after cooler as some may call it)
is apparent right? Actually, let me pose a question: have you ever seen intake air so hot that it pre-ignites the mixture in the chamber? Yep, that happens.

Discussions are welcome! Please continue.

budi

[86_ZN6]

The works non intercooled system was only driven to nevada for testing purposes.

Car will be back in the shop tomorrow for more changes and development.

A FMIC, bigger radiator and oil cooler will be added.

The car survived the intense hear of nevada. The only issue i had was an oil leak from the turbo resevior tank overflowing.

I was talking to paul AVO and he gave me a solution to the issue

[AVOturboworld]

"At peak efficiency, only about 30 percent of your fuel’s energy is used to create reciprocating power. The remaining 70 percent of the fuel’s potential energy escapes through the tailpipe or is converted into heat that’s absorbed by the cooling system."

So, if more fuel is necessary for more power, and thus more wasted "potential energy" is escaping into the system, how does it generate the same temps "if properly tuned"?

I'm not turbocharging a 12.5:1 compression, I'm not doing it on stock internals, I'm not doing it without an intercooler and I'm not running 87 octane. But you can be sure that any time I am in the market for parts, I'll talk to and ultimately buy from someone who can listen to what I'm saying.

Cool. But I'll be honest, I'm always going to tell a customer what's necessary, whether or not they like it.

[qoncept]

Originally Posted by buditjoenawan

So qoncept, your position is that an intercooler *is not* needed? And that octane ratings *does not* matter? I'm rather confused at both these assertions really. Since decades of internal combustion engine development flies in the face of the above 2 statements. I VERY well could be misreading what you're written, or misunderstanding your intentions. Please correct me if that is the case.

No, I'm saying you CAN run forced induction without an intercooler, and you CAN tune a car for lower octane fuel. In both cases you're giving up power. In both cases you're wasting a lot of money on a turbo kit and getting very little in return. Further, if you run on a lower octane fuel, you are bound by the laws of physics to actually DECREASE the temps in the cylinder.

But in neither case are you increasing the combustion temperatures. If you are, you're causing detonation and going boom.

Actually, let me pose a question: have you ever seen intake air so hot that it pre-ignites the mixture in the chamber? Yep, that happens.

Yeah, I've seen it. But I haven't blown up any of my own engines.

[86_ZN6]

Originally Posted by AVOturboworld

Cool. But I'll be honest, I'm always going to tell a customer what's necessary, whether or not they like it.

Paul i emailed you regarding the oil cap feeler replacement.

Let me know

[qoncept]

Originally Posted by AVOturboworld

"At peak efficiency, only about 30 percent of your fuel’s energy is used to create reciprocating power. The remaining 70 percent of the fuel’s potential energy escapes through the tailpipe or is converted into heat that’s absorbed by the cooling system."

So, if more fuel is necessary for more power, and thus more wasted "potential energy" is escaping into the system, how does it generate the same temps "if properly tuned"?

Fuel at certain octanes burn at a certain temperature. Period. No matter what the exhaust temperature is, no matter what the intake temperature is, and no matter what the coolant temperature is.

So, depending on what you're asking (because you are such a horrible moving target I have no idea anymore), either:

A) it's later, in the exhaust, after combustion has completed, or
B) I already fucking agreed with you that there can be temperature changes after that. I didn't phrase it quite that way but you're a smart guy, so you SHOULD be able to scroll up and find it.

Cool. But I'll be honest, I'm always going to tell a customer what's necessary, whether or not they like it.

And I'm always going to stick to taking advice from people who don't talk to about a radiator when asked about an intercooler.

[AVOturboworld]

Your PM box is full
Waiting on units though.

[86_ZN6]

Originally Posted by AVOturboworld

Your PM box is full
Waiting on units though.

Yeah i got issues with inbox. Haha. Awaiting fix from
The admins

Can you email me instead?

jrs86.zn6@gmail dot com

Thanks paul!

[Sellout]

Fuel at certain octanes burn at a certain temperature. Period.

False.

Octane rating has nothing to do with burn temperature. It is possible to formulate two different fuels having the same octane rating and vastly different burn temperatures. The octane rating shows resistance to knock, and nothing else.

If you want to claim that some manufacturer's octane boost chemical has the effect of also lowering combustion temperatures, that's one thing, but the octane rating of the fuel doesn't determine a burn temp. You're as likely to change burn temperatures by switching brands as you are by switching to a higher octane rating.

[ft_sjo]

Originally Posted by Sellout

The octane rating shows resistance to knock, and nothing else.

Is this a competition of who can talk the most shit?

Octane effects more than knock resistance. Flame front speed is also effected, for example.