From the November 2002 issue of Hot Rod Magazine, title story "More Power From Any Engine".

Cold Air

"Underhood air often exceeds 200 degrees, bad news for power because warmer air is less dense, resulting in reduced combusion efficiency and power. ...... The solution is to access cooler, denser, outside air via a sealed hoodscoop or flexible large-diameter ducts that draw from the front of the car (behind the grille or below the bumper). Though externally sourced air will always increase in temperature by the time it enters the combustion chambers, it's still cooler than anything available under the hood. ..... There is lingering controversy on whether the increased velocity of air scooped by vehicle movement actually helps pack the cylinders. We'd say that whenever throttle blades are in the flow path and vehicle speeds are less than 150 MPH, the liklihood of above-atmospheric charge density is very low, even at wide-open throttle".

This mod is included with other notable power enhancers e.g. milled heads, baby rings, reduced friction rings, oil control, electric water pumps etc.

I post this as information for those considering the merits of a top breather vs bottom breather aftermarket air system.

Les

 

:yesnod:

:smash:
:cheers:
:D

 

As a rule of thumb power increases/decreases about one percent for every ten degree (F) decrease/increase in inlet temperature, so if underhood air is inducted and it is 50 degrees higher than ambient, you loose five percent over a good cold air system. That's 17.5 HP on a 350 HP engine!

There is no potential for useful recovery of dynamic air pressure ("ram air") at less than about Mach 0.3 - about 225 MPH, and a very carefully designed inlet and diverging diffuser would be required to recover any available dynamic pressure.

Duke

 

So is it your opinion that a System, for example, the VaraRam adds power? Shocking!! I would have never guessed;) Ric

 

Boys boys boys ... hopefully this thread WILL NOT go down the ridiculous path that other one did!

I have always known that the cooler, denser air is what makes the difference, and avoid the ram air debate. As the article says air blasting in from the outside is colder and denser, with less time to heat up from the engine. Logic says that the more air moving the less heated it will become. Cylinder fill rates and positive atmosphere may, according to this article, come into play as low as 150 MPH - I am just happy to see someone who is not selling product, or being accused of defending something we already bought, come out and say bottom breathers work!

Les

 

 

It's nice that an "authority" says it. But it's nicer that "it" does it. :blueangel: Ric

 

OK now I think a prochargers will force air down the head just fine, LES get on of those and you can polish off your tranny... By the way man did you find the video of the my Z yet "Your DADDY"??????????????? :lol:

 

:yesnod:

Is there an "I Told Ya So" emoticon thingee?

:cool:

 

You still haven't taken one reading off the car and now you are quoting a WWW posting that is in turn quoting a Magazine article? Enough with the hyperspace mechanics already.

Nobody ever said that any aftermarket was going to break baro. As a matter of fact whenever my personal system gets MAP to beat baro the PCM just raises the baro reading. Stop worrying so much about pressure increases and concentrate on increasing performance.

The point is to overcome the pressure losses normally seen by any airbox design. My airbox now regularly does this in 4th gear. There is no "I Told Ya So" emoticon thingee, but there is one of these:

:nonod:

 

Will it help if I go buy Hot Rod at Wal-Mart? :)


I started to hunt down quotes, go to vararam's website and all that, but I'll respect the poster who asked that we not take it down that route again.

Anyone whose read the thread knows what was said. Ram air on automobiles is a myth.

If you are getting gains on a vararam, Halltech, Vortech or any other CAI, it is from the cooler air, not "ram-air."

A shame! :)

Ahh, that one is for Ram-air!!! I get it...

RAM AIR :nonod:


:)

 

Enough with your interpretations of myths. :mad Take some readings off your car already and tell me what you see. My car overcomes all airbox pressure losses in 4th gear and pretty much matches BARO. I actually broke BARO by .2 inHg once this past weekend and the PCM just ended up increasing the BARO reading in the middle of a pass. My 4th gear MAP is always higher than 2nd gear MAP. Is this actually 'Ram Air'? I don't care! One thing I know for sure is that this will never happen with a stock box.

My car also has a measurable increase in performance. Every single run done after the VR (without missing a gear) is faster than my stock runs. Last week my car just missed going 117 MPH and ran its biggest difference ever in MPH between the 1/8 and 1/4 mile marks. I've seen enough to know that the system works for me on the top end.

You are just looking to 'prove' that Ram Air is a myth. Others are looking for increased performance. I would be willing the bet that the people who actually run the VR at the track don't give a hoot about 'Ram Air'. They just want to go faster. I could care less what the VR WWW says. The proof is in the time slips.

Stop worrying about the definition of 'Ram Air' and concentrate on airflow rate, airflow velocity, cylinder fill rate, and performance. BTW, you will be happy to know that my in-laws just bought a 2003 Pontiac Grand AM GT with a 3.4L Ram Air V6. It says "Ram Air V6" right on the fender. Better get the call into Pontiac right away... :jester

 

I just got a predator, I don't know if it does MAPs and IATs but I will see.


Ranger is getting 120 mph in the 1/4 and if I'm not mistaken, he is using the Halltech - which is definitely a COLD AIR intake, but not a ram air intake.

Which is the premise at the beginning of the thread - Cold Air Rules

I e-mailed them! :)

 

Yeah so? He runs a different car on drag radials on a different track in different weather. I’ve yet to see or hear about any bolt-on Z06 cars running that kind of MPH at ETown and I doubt I ever will (unless Ranger comes down to ETown).

My car currently runs way more MPH than the average stock Z06 car. If you went to the track you would see that. The part looks great and fits very well. These are the only things that matter to me.


Good luck watching that tiny screen while blasting down the road WOT at 100 MPH. You are buying this and blasting the VR?. Very funny.

:lol:

 

Well, I KNOW what the predator does. I can adjust air/fuel and spark advance. I can also monitor real time info, which isn't as good as logging via Autotap, but I didn't spend $5xx on the program PLUS a laptop. AND it lets me make changes to the programming.

I don't need to watch the screen while blasting down the road at full throttle to see the IAT's. Which were interesting, to say the least!
.
http://forums.corvetteforum.com/zerothread?id=422345

Ross, I have a question? Assuming you've been autotapping since BEFORE you had your vararam - how come you didn't come out and tell us that your IAT's with the stock air filter were very close to ambient air temp?

Some other features with the predator, I was able to see my LTFT's for most modes of operation today, and they ranged between -2% and +2% under various different kinds of driving.

I can also see spark advance and MAP.

Finally, the predator has a serial port. I do not know if that means there may be a way to tap into the data and log it, or not...

Oh yeah, there is a 30 day money back guarantee, but there is no install and un-install to deal with. And shipping is negligible - it is small.


[Modified by Tom Steele, 8:56 PM 10/29/2002]

 

>Well, I KNOW what the predator does.

You do? How could you possibly know what that box is uploading? Power tuning is not a guessing game and it can vary from car to car.


>I can also monitor real time info, which isn't
>as good as logging via Autotap

The scanner on that thing is a waste of time. There are very few parameters and no data logging. You cannot even monitor fuel trim cell. For it to be useful it must be able to quickly log parameters while you drive for offline analysis. BTW - LS1Edit is not a scanner and has no scanning capabilities.


>Assuming you've been autotapping
>since BEFORE you had your vararam -
>how come you didn't come out and tell
>us that your IAT's with the stock air filter
>were very close to ambient air temp?

I did already and you didn't listen. You asked if the VR supplied colder air than the stock box and I said "not really". I never claimed that the VR supplies colder air. There are certain situations where the VR will drop IAT faster than the stock box, but generally speaking the IATs are close enough to be a wash. I've given you plenty of reasons why the VR is capable of increased performance but you have not been listening to me. You just keep bringing up "Ram Air".

>I can also see spark advance and MAP.

You cannot possibly monitor these things while driving under a load without crashing into a tree. Plus, I doubt the scan rate of that device is quick enough to be meaningful. I noticed in another thread that you were upset because the unit does not allow more than 2 degrees of advance. Increasing the TA on a stock '02 Z06 is a mistake. Shifting the entire spark curve is also a mistake. The ironic part is that you will not even be able to see all of the knock retard signals that you will be triggering. There is no parameter for knock retard. Even if the device had a knock retard parameter you would never be able to monitor this on the road at WOT. Now that is retarded.


>I want the ability to bump the timing
>a little, if I don't get KR.

Why?


>I want to raise the limiter by 200 rpm

Not something I would do.


>I want the scan tools, which are
>turning out to be better than I
>had originally expected.

Your expectations are very low. You will not be able to tune with the 'scanner'.


>I want to install a cooler thermostat
>and adjust the fans.

Your first good idea, but J-Rod & Ranger use the stock thermo & fans.


>I'd like to try their tuning, expecting
>somewhere between 5-10 rwhp.

I would expect something in the 0-5 HP range.


>Finally, the predator has a serial port. I do
>not know if that means there may be a
>way to tap into the data and log it, or not...

This cannot be done. IMO, the device is an expensive Hypertech HPP toy.


[Modified by rbartick, 10:45 PM 10/29/2002]

 

It's pretty basic Ross. Lean the a/f and advance the spark. Same thing people used to do before they had computers, by turning the distributor and re-jetting the carb.

As for the details. Actually, I can see the spark differences. All I will have to do is record them before and after the tuning. I think I am seeing about 22 degrees at WOT.

It's not as broad as the Autotap, but it is far from a waste of time. I can monitor spark advance, engine load, STFT's and LTFT's, tps, maf flow, MAP, IAT and probably some more I am not remembering right now.

Some of those aren't going to be real useful without logging, but IAT and MAP are certainly useful, as well as spark advance.

Ok, then I am REALLY lost as to how the vararam is SUPPOSEDLY making hp. If IAT's are the same, and there is no ram-air, then how does the vararam make its hp?

If you think it IS through some ducting, then how come cars with Halltechs get the same mphs as the vararams, and they are NOT using ram air?

You said I couldn't possibly know what I was talking about until I began looking at data from the sensors. I am doing that now, and I'd love to hear what your opinions are about how the vararam is making hp, when it isn't getting significantly lower IAT's or significantly higher MAPS.

Hmm, at WOT in fourth gear, I can generally avoid trees on the interstate. I just drop it in at about 65mph and WOT to redline and then let off. I can see what is happening for MAP or Spark without too much trouble.

Or I can get a driver to do it while I sit in the pass seat and watch...

I am not saying the predator is a replacement for LS1-Edit and Autotap. But it does let me look at the sensors.

I can see total spark. I assume if I advance two degrees, and I am getting 22 degrees before at WOT in fourth, then I if I see 24 degrees at WOT in fourth, then I'm not getting KR. If I still get 22 degrees, then I'm getting KR. No?

If I go buy LS1-Edit, Autotap and a vararam, will I finally be assimilated into the Borg? Why do you get so upset about this stuff when we are discussing it?

Well, as a general rule, if you can advance the spark - without encountering spark knock, you can get more hp out of an engine. The general assumption is that GM probably programmed the PCM with a tiny bit less advance than the engine can take under many circumstances to improve longevity and decrease the chance that the car will encounter spark knock.

The fact that the car CAN be run on REGULAR unleaded is circumstancial evidence that seems to support this thinking, along with a host of other areas where GM seems to have gone for engine durability over performance.

I have read enough on the 2002 valvetrain, to believe that it will take an extra 200 rpms for the rare amount of times I would use them.

GM definitely built in room for error on the rev limiter. The bottom end is solid. http://corvetteactioncenter.com/spec...inegarden.html And I believe the valvetrain will handle 200 rpms more... I wouldn't drive the car continuously at 6800 rpms, but I don't believe it will hurt things to bump that limit while drag racing once in a while.

And from what I have read of J-Rod's posts, and the bigger drop in rpms to fourth with the M12, hanging on before the 3-4 shift for a little longer can be very beneficial.

I've already learned that IAT's with the stock air filter are VERY CLOSE (within 7-8 degrees F) of the ambient air temp.

Is the condescension free? Thanks. Thermostat is cheap and I believe running a little cooler will hurt nothing but emissions, if even that.

Maybe, I have waited for the tuning download, as I want to see what other members here are getting first - and I want to monitor the engine a little with the stock programming in first.

But don't you and Ric say "every hp matters?"

I believe it does a lot more than the hypertech... no?



[Modified by Tom Steele, 1:43 PM 10/30/2002]

 

>It's pretty basic Ross. Lean the a/f and advance
>the spark. Same thing people used to do before
>they had computers, by turning the distributor
>and re-jetting the carb.

This is where you are going wrong. It is not pretty basic. Just leaning the A/F & advancing the spark is not a way to build significant HP on a stock 02 Z06.


>As for the details. Actually, I can see the spark
>differences. All I will have to do is record them
>before and after the tuning. I think I am seeing
>about 22 degrees at WOT.

Please be realistic. You will not be able to see the spark advance numbers you are getting on the road under different loads. You will also be guessing at what you think you are supposed to get. The only way to truly see what is going on is to log data while driving and then analyze it offline.


>It's not as broad as the Autotap, but it is far from
>a waste of time. I can monitor spark advance,
>engine load, STFT's and LTFT's, tps, maf flow,
>MAP, IAT and probably some more I am
>not remembering right now.

The lack of data logging and the lack of some important parameters is the problem. You are trying to work on the car without the proper tools.


>Ok, then I am REALLY lost as to how the vararam is SUPPOSEDLY
>making hp. If IAT's are the same, and there is no ram-air,
>then how does the vararam make its hp?
>If you think it IS through some ducting, then how come
>cars with Halltechs get the same mphs as the vararams,
>and they are NOT using ram air?
>You said I couldn't possibly know what I was talking
>about until I began looking at data from the sensors.
>I am doing that now, and I'd love to hear what
>your opinions are about how the vararam is making hp

Where is your data?

How much MAF are you getting through the rev range at WOT in 4th? How much MAF are you getting through the rev range at WOT in 4th? Post a data log and I will post one of mine. We need data points from 3000 RPM – 6000 RPM in about 100 RPM increments.

With respect to the VR and “Ram Air”, I am not going to keep discussing that online. We will never agree anyway. Your best bet is to just direct your questions to the manufacturer.


>Hmm, at WOT in fourth gear, I can generally
>avoid trees on the interstate. I just drop it in at
>about 65mph and WOT to redline and then let off.
>I can see what is happening for MAP or Spark
>without too much trouble.

Come on, even you can admit that you cannot do this with any accuracy.


>I can see total spark. I assume if I advance two
>degrees, and I am getting 22 degrees before at
>WOT in fourth, then I if I see 24 degrees at
>WOT in fourth, then I'm not getting KR. If
>I still get 22 degrees, then I'm getting KR. No?

No, it does not work like that. There is attack and decay. The PCM may see knock and retard for a second or so retard and then re-advance. It depends on many variables. The only way to monitor this is to include Knock Retard in a data log.


>Well, as a general rule, if you can advance the spark –
>without encountering spark knock, you can get more
>hp out of an engine.

This is false. Advancing the 22 degrees TA results in a gain of about 0-1 HP, and additional spark knock.


>The general assumption is that GM probably
>programmed the PCM with a tiny bit less
>advance than the engine can take under many
>circumstances to improve longevity and
>decrease the chance that the car will encounter spark knock.

This is an assumption that will be disproved by data logging with 93 Octane Street Gas. Furthermore, just because a motor can take more advance that does not mean that it will make more power with more advance.


>The fact that the car CAN be run on REGULAR
>unleaded is circumstancial evidence that seems
>to support this thinking

This is wrong. First of all pretty much any stock Z06 will sometimes knock a little and see some knock signals at WOT with even the stock timing and 93 Octane street gas. This can depend on gas quality, weather conditions, engine load, etc.. Run 87 or 89 octane and you will knock a lot, forcing the PCM to switch to a different timing table. So as far as your circumstantial evidence goes, run on 87 Octane and your PCM will end up running a different timing table with less advance everywhere.

Advance your timing beyond 22 degrees TA and you will see about a 0 HP gain with additional knock signals. It will probably end up knocking pretty bad when the cars gets under a load after the 3-4 WOT shift. It will also knock in 1st at a low RPM WOT launch. The only way to see this is to data log spark advance along with spark knock.


>I have read enough on the 2002 valvetrain, to believe that it
>will take an extra 200 rpms for the rare amount
>of times I would use them.

This is still not something I would do. The extra 200 RPM is not worth the risk.

>I've already learned that IAT's with the stock air filter
>are VERY CLOSE (within 7-8 degrees F) of the ambient air temp.

Agreed, but it does take them a little longer to get there in hot weather.