David,

Do you still prefer not to use fans when dyno testing?

Shiv

 

Are you suggesting that coolant temp based maps could be responsible for the extra enrichment on the dyno?

 

The 10.5 housings are all about the same, not enough difference in either one to determine which is better. The 9.8 housing works well too, not sure if the cost of upgrading to either turbo is worth the money over the stock '03-'04's.

I don't know what got me off on such a tangent to make power with the stock turbo. I believe it is because I enjoy driving the car so much with that instant power that the stock turbo makes.

Right now the car looks like it would run its best with either of the 10.5 housings on it. The spool up is the best like this with very little power loss up top compared to an external wastegate on the stock turbo. SO, like this the car is making 380 whp and 370 ft lbs of torque.

To duplicate this exact set up on another EVO the break down would look like this:

Buschur Racing Stage 4, this is minus the AFC, $3430.
AEM EMS, $2400
Ported intake manifold, $75
BR 65mm throttle body, $300
Ported exhaust manifold, 02 housing and turbine housing, $300.

This is what is making the power in the car, total is $6505.

My car also has the Exedy clutch in it but any clutch could be used or stock until it fails.


Comparing this to adding a larger turbo kit, as someone asked. A turbo kit with a GT30R, cheapest good kit out there is probably ours and is priced at $2800. Not sure if there is a complete kit out there cheaper.

On pump gas I don't feel you can safely make much more power than we already are on the stock turbo. On race gas you can make 500 whp with this turbo.

David Buschur
www.buschurracing.com

 

It has nothing to do with the coolant as the temps stay the same on the dyno as they do the street, thermostat controls engine temps and the cooling system in the EVO keeps them stable.

Shiv, if I actually answer your question would you do the same for someone else?

David Buschur
www.buschurracing.com

 

Hiya,
It is moreso an issue of running an air/air intercooler on a dyno without a cooling fan. Without a fan, IC efficiency drops for the 80-90% you see on the street to 50-60% (or less depending on run duration, number of runs, cooldown between runs, etc,.) you see on the dyno without fans. This means that instead of the IC removing 80-90% of the heat gains introduced by turbo compression, it only removees 50-60%. The difference, as far as intake charge temps go, can be massive and induce commensurate changes to fueling. Especially when running standalones with user-defined MAT (manifold absolute temp) compensations.

Another issue with tuning a car without fans and fresh air ducts is one of air contamination. Exhaust gas is enert and doesn't combust. Instead it just takes up space in the air charge which would otherwise with used by fresh, power-making, oxygen-filled air. Without fresh air ducting to the front of the car (and sufficient exhaust gas ducting from the tailpipe to outside the shop), the air in the dyno shop will tainted by exhaust. A 10% exhaust gas mix in the air will induce a ~10% reduction in power through oxygen density change alone, not to mention the power reduction caused by increase in ambient air temp. The fuel requirements in this instance will change proportionally as well.

The point of the matter is if a 15% fuel adjustment is necessary between a dyno and the road, the dyno conditions need to emulate the road better. This isn't a reflection of the dyno but rather a reflection of how and where it was set-up. This is one reason some companies spend thousands and thousands of dollars on their dyno cells.

Hope that clears things up and doesn't spark a flame fest...

Peace,
Shiv

 

Thanks. In wideband datalogging my car on the street, I have noticed that it gets significantly richer with successive WOT 3rd gear pulls to redline if I don't allow cool down time between pulls. Al told me that this is a function of coolant temp correction (which is what prompted my question) and to make sure that I give the car a chance to cooldown between pulls to make accurate adjustments to the fuel curve. Whatever the reason, whether it be FMIC efficiency related or otherwise, I can see where fans on the dyno would enable you to spend more time dynoing and less time on cool down.

 

Please egnore my egnorance of enert gasses, I emagine I entended this to be funny and not a flame or spelling police. Just having some fun .

Seriously, I appreciate your contributions to the EVO community.

 

Evom needs a spellcheckAr!

shiv

 

Thanks for the post Shiv but the points you are making don't apply to what we are seeing happen. Although you are absolutely correct in what you are typing.

First, our dyno is set up so the back end of the car actually sticks out of our building. The door, when it is cold outside is closed to the back of the car and the sides are sealed. I get extremely "sick" from the carbon dioxide almost immediately anymore, this was why we changed our dyno around like we have. One good smell of exhaust and I am high and nausiated (SP?).

Also I log the air intake temps which are of course after the intercooler. I just went back and dug up logs from the dyno testing. The way the car sits right now, 393 whp, 94 octane, I was sitting idling for a long time in the car, air intake temps were 73.4 degree F, I made a 3rd gear pull and at the end of the pull the air intake temps were 77 degrees. This as you know will not effect AFR's. Now I pulled up the same combination on the street, driving down the road at a steady state cruise the air temp in this other Stage 4 car was 68 degrees when the car went to WOT, 1,000 rpm later the air temps dropped to 64 degrees and then started to climb, at the top of 3rd gear they were still only 80 degrees.

While the temps are different as you can see they are not different enough to support what you typed.

In our case, the actual load that the car sees is what causes the problems. I find this same thing happens with the RWD cars we dyno here, even with large tires/slicks the AFR's change once they hit the track.

Maybe it's the inertia dyno, that is my only reasoning behind it. The car isn't loaded as hard as it is on the road.

David Buschur
www.buschurracing.com

 

Why would this be a shocker? This confirms what I've suspected for quite a while now. On the street, especially at higher speeds, more air is fed into the intake. With the stock intake this is probably even more of a case than with an open air intake, since the stock airbox should act like a ram air intake at high speeds. When I had my Evo tuned on the dyno, it was tuned fairly close to where the ECU would pull timing and summarily when I go WOT in 4th/5th gear at 80+mph, my ECU will pull timing. IMO anyone tuning for top speed/high speed performance will need to do so by street tuning with a wideband O2 sensor and logger...

l8r)

 

Glad to see you have a sense of humor.....slow day at the office for me I guess.


Speaking of gasses.........

 

Okay, I guess I am the gas police. David, don't you think it is the CO not the CO2?
BTW, Can't wait for my TBE, BC and air intake to get here from Ohio! Keep op the good information this thread is providing.

 

More air being fed into the intake of a car with a MAF-based EFI system shouldn't cause the car to run leaner, though I agree on street datalogging for high gear extended WOT runs. The load at higher speeds in higher gears is obviously much greater than what the car sees on the dyno. I wouldn't be surprised to see much leaner AFRs in 5th gear at 120 mph than on the dyno, but I assumed that we were talking about more typical road speeds in a comparable gear.

 

I believe that the issue with dyno tuning reletive to road tuning is the fact that the load the car is subjected to on the street varies pretty dramatically with speed. Aero resistance goes up exponentially with speed. (squared I believe, but not sure off the top of my head). This means that in each successively higher gear on the street, the load applied due to aero resistance alone is drastically different. Unless the dyno has a way of calculating the wind resistance that the car would be subjected to at the road speed applicable, and varied the resistance generated by the dyno accordingly, there would be no way to know. I would imagine that what you would see on the street would be successively leaner afr's in each gear through the same rpm range. With a turbo car, I can't imagine that the ram air effect would have anything but a small effect on intake charge temps.
Mark

 

In addition, I believe that a well setup ecm could be programmed to take the rpm, and vehicle speed into account, and adjust wot mapping accordingly. Just an idea.
Mark