How did you measure those intake temps at the manifold? Were they direct or from the OBDII?
cheers,

 

I found the opposite...ie, immediately post IC's temps were generally a few degrees higher than further down stream at the OBD's sensor...

For instance, if pre-IC temps was around 145F and if the post-IC was around 85F, then the OBD's reading would be around 75F...don't ask me why...

 

Why do you think you saw that?

 

Asked for that one didn't I?

 

I alluded to this, and a plausable reason starting on post #13 here:

https://www.northamericanmotoring.co...lta+front+back

I truly feel that measuring temp on the back or rear portion of the DFIC, or similar design, will yield the highest figures, as compared to the front where the air is truly ambient at that entry point...

 

Tony: I think I recall in that thread, Sid responded by posting the location of his TCs, which I have replicated with my installation. If there's an "optimal" place to locate them to avoid any differential distribution of temperatures, surely smack dab in the middle would be a good candidate? And since the probes line up they measure from the same point in the entry, and exit distribution.
I listened to Sid when he said not to use the location provided by M7, at the back corner of the in, and out, plenum chambers of the DFIC.

cheers

 

My apologies. I just assumed that the provided bung in the rear was being used... I agree, as I also stated in that thread, the middle would seem to be the prime location for the truest semblance of IAT.

 

Still interested by this high inlet temp thing.
Sadly we have 4 days of ***** weather coming so I can't swap my boots and gauges back in and try with and without the VGS mod.

What pulley are you running DPG?
I'm at 15 Sid is 15+2 and you are........?

If the 15+2 makes that big a difference I'm not going there I'll keep my cool inlet temps thank you.

My probes are different but the tip is in much the same location as yours. Since they do enter from the back side of the boot if they were gong to be in error you'd think it would be to the high side ala Tony's link.

I have compared the readings I get from the probe to a borrowed pyrometer and they were within ± 2º.

 

My next test steps are:
1. collect some data this afternoon when ambient temperatures are higher.
2. check ambient temperatures cold tomorrow AM with calibrated thermometer.
3. "undo" the VGS and gather data.

WRT the high temperatures: no one has responded to my post re: the initial M7 temps (inlet 183deg.) and Webb's (260+ deg.) I was just talking with Peter of M7, and he's not at all concerned about my inlet temps--he seemed to think they were quite reasonable. Here's a list of possible reasons for the anomolies:
1. My probes are in error.
2. My guage is not calibrated. (Even though it comes calibrated from the factory to the probes actually fitted.)
3. The VGS is to blame.
4. The probes are located in the wrong place.
5. The probes are heating up via transmission of heat from the IC body.
6. The altitude of Alb. NM increases inlet temps.

I am running a 15% only, so it would not seem to be the culprit.

Alternatively, I have a really high efficiency IC (88% remember!)

cheers,

 

In my case, the temps were taken prior to the addition of the 2%...in anycase, the temps dropped dramatically once I removed the VGS...

I'm not saying the VGS is definitely the culprit but I've tried installing this mod twice and both times I got a dramatic temperature spike...

 

I thinking your mounting location is fine but I do think you should insulat from the horns if you have not already done so.

 

Here's my reply to Phil regarding his same concern:

I wouldn't worry about it too much Phil...it will only affect the readings during heat soak and you want to avoid that situation anyway

Besides, it's a good way to see how high your DFIC's temp is going while stopped in a traffic jam

A grommet may cause leak under high boost pressure...I'd avoid that...

My OBD IAT sensor reading interestingly shows around 5F lower temp than the post-DFIC sensor...I think this is due to the direct contact of the probes to the DFIC...knowing that, I adjust my interpretations accordingly...

 

A 200F IAT at a steady 70 mph cruise (more or less flat) is really high, in my experience. I've made measurements, with VGS, on a 15% and 19% pulley, and only get into the 200 F and beyond range while accelerating. At 70 mph cruise, the intake pressure is like -10 mm Hg, so the BPV is probably open. IATs in this situation are around 125-135 F, when ambient is ~70 F.

 

IAT would be better represeneted by the outlet temp of the IC, or in Phil's case, 60F...

 

Well, true enough. The word "inlet" is ambiguous unless the particular inlet in question is identified. I was thinking about the IC inlet.

 

inimmini: How did you measure the core-in temperatures on you IC (the air coming out of the SC, into the IC)?

Also: do we have a database of air temperature measurements, or will I have to do this myself? They seem to be all over the place: 120F at 70mph, 200F at 70 mph, Webb's at 260+, Peter of M7 at 183F. That's a lot of variance...


cheers,

 

Hi all, couple of items to ponder....

The manifold guage should always read a bit cooler than one upstream... The pressure drops allow for a bit of gas expansion. To check the relative gauge readings, check the temps they all read after the car has sat for a VERY LONG time. But this really isn't enough. You should check their reading in boiling water too.

IATs can be all over the place. One configuration I was testing saw post IC temps over 300F! So watch any possible source of ingress of post radiator heated air, or parts that get blasted by radiator air as well. This is probably a very good way to see how well the intake is working too!

While you're all looking at the IATs.. look at the MAP value as well. MAP/(temp in degrees C + 273) is proportional to air density. This tells you potential power. Also, detonation is an effect of both variables..... Too bad there isn't a pre-SC pressure reading!

Anyway, fun reading!

Matt

 

Dr. Phil,
I just slid the thermocouples under the boots on either end of the IC, and tightened the clamps back up. I'll have to check, but I think these are J type TCs- just two wires of different metal twisted together. Very slender and sensitive to temp changes. The only trouble with my method is that the TC is positioned near the wall of the inlet/exit horn, rather than in the middle of the flow. If the fluid flow were slow and laminar, there might be a significant difference between the temps at the center vs at the wall. Given the turbulent air flow in the inlet/exit horns, this positioning probably does not introduce much error.

Truly, there is a lot of variation among the air temp measurements. It is probably most meaningful to compare temps measured by one person on one car as a function of various changes in the set-up (different IC, scoop, etc.) rather than to compare results from different cars/people. Also, the temps change so rapidly when accelerating that you'd really need a logging device to accurately compare these transients, which I think some of the really high numbers out there are coming from.

 

Well then...my probe's reading are just about right then

inimini...you're probably loosing some boost if you're running wires (no matter how small) throught the clamps...they have a hard enough time holding a good seal without a couple wires running through them

 

For sure Sid.
I need to undo the mod on mine. I ran the hoses so it's easy to do.
It'll take more work to reinstall the boots.

The upside could be I have some reeeeeally low inlet temps.

 

I figured that is what you meant, but wasn't sure. IAT should not be ambiguous as it is considered to be the temperature of the air as it enters into the combustion chamber. Maybe for this dicussion, IAT-IC... Pre/post core might just be easier...

Great discussion!

 

Gotta disagree with this one.
The metal of the IC throat will always be hotter than the air flowing through the IC under any condition I can think of.
The probe in effect will act as a heat sink which draws the heat from the metal through it.

Might be an OCD Meeting "topic for discussion"

 

Very close to what I see. Well within a margin for error.
A 50-70º difference is something different.

And the beat goes on......

 

Here's a screen shot of a spreadsheet from early this year.

VGS, GRS IC and stock scoop

 

Ok...whoever can still manage to hold their case after CustomAV's kegger wins the debate

We'll have to steal his brew as he has a long way to becoming an OCD member from what I saw of his Mini at the last event Jokn Chris...