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Mk7 big turbo mpi dyno number/reliability

Ed @ EQT

Ed @ EQT

GOLFMK7 Official Sponsor
Location
Fairfield, CA
Car(s)
MK8 Golf R
SugarMouth said:
Up here in altitude I get to lap three and start to overheat. Thin air life.
Click to expand...



Really? What overheats?

I’m able to run all day in 100+ heat with no issues.

— Ed
 
Ed @ EQT

Ed @ EQT

GOLFMK7 Official Sponsor
Location
Fairfield, CA
Car(s)
MK8 Golf R
THEREALVRT said:
I agree 100% with you on this Ed but you have to be careful, if you have a motor issue some people on here will jump down your throat and next thing you know you'll be a bad tuner, as some here as mentioned about another tuner in this thread.

People don't understand if you want to find the limit you have to get to the limit, some people use customers cars for this, some use their own. I perfer the latter!!
Click to expand...



I’m definitely not trying to blow anything up, but I’m also not pussy footing my personal car. I’d much rather find the limits on mine than a customer’s.

— Ed
 
Ed @ EQT

Ed @ EQT

GOLFMK7 Official Sponsor
Location
Fairfield, CA
Car(s)
MK8 Golf R
Hoon said:
I haven't verified this for MK7s specifically, but most map sensors are 5 volt sensors that read in about 0.25 volt increments.

As a result, a 2 bar sensor will have double the resolution of a 4 bar, because it only reads half the range with the same number of potential outputs.

A 1 bar sensor has like .72 psi resolution, but a 4 bar is about 3psi between each voltage increment.
Click to expand...

I don't think this is correct. The MAP sensor calibration is a linear voltage/pressure relationship and the ECU interpolates along that line. The limiting factor on resolution is the voltage output of the sensor and voltage detection circuitry in the ECU, and off course the data type that is used by the ECU. Most circuits easily detect changes as small as .01v which would give us at least 400 points across a 4 volt range (most sensors operate at .5-4.5 volts). So the resolution on 1 bar sensor is at least .04psi, on a 3 bar that would be about .1psi, and on a 5 bar it would be around .2psi. Accuracy is the other factor and that generally varies with temperature. This is usually .5-1.5% of the full operating pressure range across the operating temperature range. Most 3 bar sensors are accurate to about .25psi across their operating temperature range. The AEM 5 bar sensor is accurate to .375psi across its temp range and the Bosch 4 bar seems to be at about .88psi, but the inaccuracy is only at either temperature extreme... in a more normal temp range, they're accuracy goes up to about .5psi. But again, resolution is much much higher than that.

Now on to the problem with the Bosch 4 bar... I think its the the pressure range rather than the resolution. The little data I've found on it, says it only reads down .5bar (-7.25psi relative vacuum at sea level). This is not enough for a gasoline engine as they tend to idle and operate at low throttle in the -9psi to -12psi range. So this sensor won't work properly when used on the manifold for load/fuel calculation. It'll work fine as a TIP sensor since it doesn't need to measure vacuum there. The AEM 5 bar, for example reads down to 0 bar (-14.7psi relative).

So this explains why some of you are having idle and low throttle drivability issues with the Bosch 4 bar in the intake manifold. There could be software tricks around this by calculating low load based on baro pressure, temperature, and throttle angle, but that's far from ideal. So until we can find a better a P&P 4 bar solution, it seems that the AEM sensor is the best bet.

Thanks
-- Ed
 
THEREALVRT

THEREALVRT

Drag Racing Champion
Location
The great white north
Car(s)
Golf R
Ed @ EQT said:
I don't think this is correct. The MAP sensor calibration is a linear voltage/pressure relationship and the ECU interpolates along that line. The limiting factor on resolution is the voltage output of the sensor and voltage detection circuitry in the ECU, and off course the data type that is used by the ECU. Most circuits easily detect changes as small as .01v which would give us at least 400 points across a 4 volt range (most sensors operate at .5-4.5 volts). So the resolution on 1 bar sensor is at least .04psi, on a 3 bar that would be about .1psi, and on a 5 bar it would be around .2psi. Accuracy is the other factor and that generally varies with temperature. This is usually .5-1.5% of the full operating pressure range across the operating temperature range. Most 3 bar sensors are accurate to about .25psi across their operating temperature range. The AEM 5 bar sensor is accurate to .375psi across its temp range and the Bosch 4 bar seems to be at about .88psi, but the inaccuracy is only at either temperature extreme... in a more normal temp range, they're accuracy goes up to about .5psi. But again, resolution is much much higher than that.

Now on to the problem with the Bosch 4 bar... I think its the the pressure range rather than the resolution. The little data I've found on it, says it only reads down .5bar (-7.25psi relative vacuum at sea level). This is not enough for a gasoline engine as they tend to idle and operate at low throttle in the -9psi to -12psi range. So this sensor won't work properly when used on the manifold for load/fuel calculation. It'll work fine as a TIP sensor since it doesn't need to measure vacuum there. The AEM 5 bar, for example reads down to 0 bar (-14.7psi relative).

So this explains why some of you are having idle and low throttle drivability issues with the Bosch 4 bar in the intake manifold. There could be software tricks around this by calculating low load based on baro pressure, temperature, and throttle angle, but that's far from ideal. So until we can find a better a P&P 4 bar solution, it seems that the AEM sensor is the best bet.

Thanks
-- Ed
Click to expand...

very well said sir!
 
P

pieguy

Ready to race!
Location
Bay Area
Anybody have insight on where to buy the aem 5 bar and how to mount it? I asked APR but a timely response from them is impossible.
 
SugarMouth

SugarMouth

Drag Race Newbie
Location
Nevada
Ed @ EQT said:
Really? What overheats?

I’m able to run all day in 100+ heat with no issues.

— Ed
Click to expand...

The dry/thin air does not transfer heat well. I have spoke to others also at high altitude with the same issue.

I will see 240+ degrees of coolant temps by lap 3 at High Plains Raceway. The car basically turns unto a Geo Metro in terms of power and I have to do a lap at 50% to cool down. At that point my first hot lap it's overheating again.

Will need a better radiator.
 
Last edited:
Diggs24

Diggs24

Autocross Champion
Location
de plains! de plains!
Car(s)
2015 GTI
vw671 said:
:(


https://www.youtube.com/watch?v=M5LrRndgqJQ
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"I'm in school and have no money."

 
P

psychonosspaz

Go Kart Champion
Location
PNW
Wow that sucks :(


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