aurora40

iTrader: (1)

I took the car for a run while datalogging. What I wanted to see was how much the MAP pressure drops when at WOT. So that I can figure out if a CAI/etc is even possibly worth it.

I wanted to try a pull through 3rd gear, but it just wasn't possible to max the car out on the roads I was on. I did pull to about 6,200 RPM, but then I ran out of space and had to get on the brakes.

So instead, here is a 2nd gear pull:



The MAP pressure spikes up there to 100.5 or so, but I did several WOT measurements in 5th and 6th gear, and never saw higher than 99.96. So I am considering 99.96 to be the "real" pressure when I was measuring.

It drops to 95.97 as the lowest reading. So that is a 4kPa pressure drop. If a CAI/intake tube could reduce that to a 1-2kPa pressure drop, on a 400hp car, that should be an 8-12hp gain.

Also interesting is that the airflow peaks at 6,350 RPM. GM says the power peak is at 6,000.

I think a 3rd gear pull probably would have had smoother lines, as it would have happened over a longer period of time.

Also the timing is not very constant at WOT. I don't know if there is KR happening, or that's just the normal timing curve stock. This particular scan tool doesn't read KR.

And the throttle position never goes past 88%. I've seen that on other electronic throttle cars, I don't know what that really means, though. I assume the throttle opens all the way, in spite of that reading.

aurora40

iTrader: (1)

Not interesting? Or is the graph hard to read? Or did I sum it up 100%?

ColeGraham

iTrader: (8)

i read this at work, but the graph picture was block...haha

but it is a very interesting read.

liqidvenom

iTrader: (2)

that is pretty cool to see... what did you use to do the scan.

aurora40

iTrader: (1)

It's an Innovate LM-2. It's a wideband recorder, but also does OBD-II.

aurora40

iTrader: (1)

I'm sort of wondering if something like the K&N CAI would be worth it and maybe gain that 8-12 hp. Or if that pressure drop is small enough that there's not much gain to be had.

liqidvenom

iTrader: (2)

well the only proper way to check it would be to install it and find a similar day to do the same tests

aurora40

iTrader: (1)

True, but if it turned out it wasn't worth it, I'd already own it!

I'm not sure the weather has to be similar, though, to compare the pressure drop. Certainly to compare the mass of air.

itsslow98

iTrader: (18)

I made 8hp more then another guy on here with the same mods on the same dyno with the same tuner except he was running a stock airbox and I had the K&N intake. But with the K&N i guarantee id be down 20hp on a 90 degree day.

aurora40

iTrader: (1)

Do you mean down 20hp over the stocker? Or over the performance on a normal day? Any intake system will perform worse when it's hot out, there's no reasonable way to get intake air that is cooler than ambient (nitrous aside).

There don't seem to be any other intakes for the LS2 cars, besides the K&N. They have some line attached to the intake ducting that the other setups don't have a provision for. Maybe I need to look at truck intakes?

I'd like to try removing the intake ducting and scanning the car, just to test the theory prior to committing. But I'm not sure how to safely and practically do that. Maybe some coupler for the MAF, then put like a sock or something over the MAF end just to keep larger crap out of the engine? That sounds kinda horrible, though.

Twitch1

I get 100% throttle in my scans. It could be something as simple as your floor mat getting in the way.
Since your in third gear, and this is just a guess, it might be traction control pulling some timing. Was the road a bit rough?

Tony

itsslow98

iTrader: (18)

Heat soak, so down 20hp, when its hot the K&N does a horrible job of getting any colder air in the car. Even when its like 70 i get heat soak from the engine bay.

JJSimon904

iTrader: (8)

If you have a choice, go with the Volant. It is cheaper and is as sealed off from the engine bay as you can get. My IAT's are very nice even sitting in traffic.

-T-

iTrader: (2)

I am interested in more of your thoughts with the data logs. I data logged a few runs of mine with the OT-2. It seems as though the default measurements (%, inHg, and such) were not 100% correlated. The easy ones I could figure out. The mass was displayed in inHg, WIERD!. I am 99.9% positive it should read in cfm. I have been wrong before, and it will happen again. So I am not sure.

aurora40

iTrader: (1)

I don't know if the OT-2 is the same as the LM-2. But I have to configure the "channels" in the LM-2 to record. Then when viewing it in the logging software, I again have to configure which "channels" were which. So if you don't pay attention, they can be wrong.

It's pretty poor, as is the way you configure channels to record on the car. You have to pick ahead of time exactly how many things you want to monitor, then set what they are, vs just going through the list and checking which things you care about.

You can change the units though. But mass, should be some unit of mass per time. CFM is actually a measure of volume per time, not mass. You'd have to know the temperature and pressure to know the mass from that. It's generally grams/second or something like that.

inches of mercury is a unit of pressure. I prefer kPa simply because it is a larger scale. 96 vs 100 kPa is easier to understand (to me) than 28.7 vs 29.9 "Hg.

aurora40

iTrader: (1)

AFAIK, the K&N is the only one with a provision for the fresh-air tube the LS2 has attached to the intake ducting.