TURBO SYSTEMS, WHO DO YOU LIKE?

[ASD]

Better be careful Pog, between Alans clutch and Johns trans you may catch a bum converter just by hanging out with them.

If I remember right the last car I pushed in the shop was a AFP car at 11:30PM on a Saturday night. Don't worry I covered up his stickers with blue tape.

 

[AllFordPerf]

Well when you have more than 5 customers the odds are one will break eventually. It could have been worse he could have been stuck on a bridge or broke at the track.

 

[ASD]

Well when you have more than 5 customers the odds are one will break eventually. It could have been worse he could have been stuck on a bridge or broke at the track.

Wow....Someone head is getting big. Your starting to sound like another shop up there. You must not have much to do since you keep responding to these post?

I better go, I need to total a customers saleen today.

 

[352Ford2]

please show me an example of a car with too big of an intercooler.

I think the easiest way to visualize this is with a very specific case.

Take an air to air aftercooler, fixed inlet temperature, and fixed ambient temp.
Eic= aftercooler efficiency
Tin= temp into aftercooler
Tout= temp out of aftercooler
Tamb= Ambient temperature

Eic= (Tin-Tout)/(Tin-Tamb)

Graph intercooler efficiency vs. size of intercooler given the stated constants. You will get an asymptotic graph as it approaches 100% efficiency (decreasing rate of return for what you are putting in). Assuming you picked appropriate numbers for the Tin and Tamb, you want to size your intercooler to the size just before the graph “flat lines”


It is true as you increase the size of your intercooler you are increasing the efficiency of the system (getting the outlet air temp closer to ambient temp) but at an increase in system (turbo) lag and pressure drop and once the graph “flatlines” you really are not gaining anything.

 

[1-Slow5.0]

Gosh, I can't take this anymore...!!!

!@#$%&*

I think I need to go on a 90 mile test drive!

(OK, guys, you KNOW I'm SOOOO just kidding on that one... but I had to.... )

 

[Jon]

I think the easiest way to visualize this is with a very specific case.

Take an air to air aftercooler, fixed inlet temperature, and fixed ambient temp.
Eic= aftercooler efficiency
Tin= temp into aftercooler
Tout= temp out of aftercooler
Tamb= Ambient temperature

Eic= (Tin-Tout)/(Tin-Tamb)

Graph intercooler efficiency vs. size of intercooler given the stated constants. You will get an asymptotic graph as it approaches 100% efficiency (decreasing rate of return for what you are putting in). Assuming you picked appropriate numbers for the Tin and Tamb, you want to size your intercooler to the size just before the graph “flat lines”


It is true as you increase the size of your intercooler you are increasing the efficiency of the system (getting the outlet air temp closer to ambient temp) but at an increase in system (turbo) lag and pressure drop and once the graph “flatlines” you really are not gaining anything.

With the volume of air that you're flowing the volume of the cold side is totally irrelevant, you're arguing miliseconds. As for pressure drop, you're assuming a fixed air volume going in and that's just not the way it works since the control system fights to maintain a fixed pressure at whatever point you take your reference signal from. The only realistic possible downside of putting in an intercooler that the math says is "too big" is the added weight, cost and/or effort to actually install it. There is a point of diminishing returns, but it certianly won't hurt anything hence my request for an actual example. Bottom line is you won't find one.

The math is great until you get to the real world and realise that it's only about 1/3 of what's really going on

 

[WaterPog]

With the volume of air that you're flowing the volume of the cold side is totally irrelevant, you're arguing miliseconds. As for pressure drop, you're assuming a fixed air volume going in and that's just not the way it works since the control system fights to maintain a fixed pressure at whatever point you take your reference signal from. The only realistic possible downside of putting in an intercooler that the math says is "too big" is the added weight, cost and/or effort to actually install it. There is a point of diminishing returns, but it certianly won't hurt anything hence my request for an actual example. Bottom line is you won't find one.

The math is great until you get to the real world and realise that it's only about 1/3 of what's really going on

That was me, not Jon.

sorry.

 

[loud 95]

keep in mind their is such thing as too big of an intercooler (or aftercooler as they should be called )

Well, I don't think that I could fit "too big" of an intercooler under the front fascia of my '95 GT. It is better to have an oversized intercooler than an undersized one. In my case, the intercooler is going to have to chill the charge for a 427ci engine, with a fair sized turbo. The stage 2 B&G kit is too small in every respect to support this endeavor. Their stage 3 kit is what I want, but it features an air-to-water intercooler. My plan for the car is to drive it to the track, race the hell out of it and then drive it home (assuming I didn't break anything). As such, I require an air-to-air intercooler. Correct me if I am wrong, but the requisite intercooler for this plan should qualify as, "big ass."

 

[352Ford2]

With the volume of air that you're flowing the volume of the cold side is totally irrelevant, you're arguing miliseconds.

I may be misunderstanding you (please correct if I am), but if the volume difference is not significant between the inlet side and outlet side that means your aftercooler is useless (PV=NRT).

As for pressure drop, you're assuming a fixed air volume going in and that's just not the way it works since the control system fights to maintain a fixed pressure at whatever point you take your reference signal from.

As stated above this is a very simplistic example meant to shed light on the thought process required to select an aftercooler, this quick calculation would only apply at a given engine rpm, load, ambient temp, etc.

The only realistic possible downside of putting in an intercooler that the math says is "too big" is the added weight, cost and/or effort to actually install it. There is a point of diminishing returns, but it certainly won't hurt anything hence my request for an actual example. Bottom line is you won't find one.

Sorry, I am going to stick to the system lag and pressure drop issues, that’s just the way system cycles and fluid mechanics work. Wikipedia has a pretty good write up on thermodynamics and fluid mechanics:
http://en.wikipedia.org/wiki/Thermodynamics
http://en.wikipedia.org/wiki/Fluid_mechanics

The math is great until you get to the real world and realize that it's only about 1/3 of what's really going on

While it’s true that things between theory and reality can get convoluted sometimes, if you want to optimize a process, it is the best way to get you in the ballpark close enough to test, just ask an F1 team engineer.

 

[352Ford2]

It is better to have an oversized intercooler than an undersized one.

For us enthusiasts that generally “thumb” stuff, you are 100% correct.

 

[WaterPog]

Yes, you did misunderstand. The volume of the pipes relative to the volume of air going through the pipes is so small that any change in "lag" due to increasing the pipe length or intercooler volume is going to be insignificant.

The best rule of thumb is "put in as big a cooler as you can fit and quit over thinking it."

 

[loud 95]

For us enthusiasts that generally “thumb” stuff, you are 100% correct.

I know one alternative is to use a smaller intercooler and utilize a water/methanol kit to bridge the gap, but I would prefer not to introduce yet another system into the car. We'll see.

 

[352Ford2]

I know one alternative is to use a smaller intercooler and utilize a water/methanol kit to bridge the gap, but I would prefer not to introduce yet another system into the car. We'll see.

Corky Bell (a man that knows far more than any of us about this sort of thing) thinks water/meth injection area bandaid fix for an improperly designed system. I do not fully agree and think they do have their merits in certain situations, but I will say this: if your water injection system clogs and your tune depends on it...... BOOM!

and leaky systems can cause issues too.

 

[WaterPog]

Methanol definately has a place, but not really as a cooling agent primarily. The guys who are making big power with methanol injection are using it to actually replace a large quantity of fuel under boost, sometimes as high as 50%, and taking advantage of it's much higher octane rating in addition to the cooling effect.

 

[loud 95]

Corky Bell (a man that knows far more than any of us about this sort of thing) thinks water/meth injection area bandaid fix for an improperly designed system. I do not fully agree and think they do have their merits in certain situations, but I will say this: if your water injection system clogs and your tune depends on it...... BOOM!

and leaky systems can cause issues too.

It does seem that many people (especially in the import world) are using water/methanol injection as a cheap means of making up for the lack of an adequate fuel system. It should be used by those who run their cars hard on the street with pump gas and want to run cooler while enjoying a higher threshold of boost capability and detonation protection. The only way I would run a water/methanol kit on the street would be if I had a means of monitoring the system to assure it is injecting properly. This is getting easier to do, as enough of the new stand alone systems have sensor input options for use in situations like this. One could certainly monitor the fluid level in the storage tank, as well as the pump voltage. Even so, there is certainly inherent risk involved any way you cut it. Once I get the car together, I would prefer trying some tuning on E85, over installing water/methanol injection.

 

[loud 95]

Methanol definately has a place, but not really as a cooling agent primarily. The guys who are making big power with methanol injection are using it to actually replace a large quantity of fuel under boost, sometimes as high as 50%, and taking advantage of it's much higher octane rating in addition to the cooling effect.

Agreed. The best example that comes to my mind is Mark's supra from Torque Freaks. I remember two years ago at the dyno day when people got hit with a mist of methanol from his car. I don't recall where it was all coming out of, whether it had been a leaky sytem or simply exhaust emissions. I think he put down just shy of 800rwhp. Methanol in the eyes doesn't feel good.