Heat Soak Testing an ESS VT1-535 with IAT data and vBox results

[Alekshop]

Heat Soaking the ESS VT1-535

Preface:

Questions occasionally arise about the effects of heat soak on the ESS VT1-535 supercharger kit. This kit comes from ESS without an intercooler and there seems to be an assumption that a small amount of heat, temperature, back-to-back performance runs, or sustained endurance tests cause a noticeable degradation to the VT1 performance. To measure heat soak on the VT1, one needs to measure IAT: Intake Air Temperature. The IAT of the non-intercooled VT1 is expected to rise during hard racing, but does it rise enough to affect performance?

We got the idea to run an IAT heat soak test on the VT1 after seeing these questions about heat soak, but didnt know how to log IAT at the time. The last time anybody data logged an ESS VT1 was at the Trona Airport event; and at that time, nobody had yet figured out how to log IAT data. I suppose its possible to use circumstantial evidence to deduce the effects of heat soak on the VT1, but without actual IAT data, the results will never be anything but circumstantial.

Preface:

To build a circumstantial case, one could look at the many temperature logs available, and correlate those temperatures to the vBox results. If heat soak was evident, the cars performance should decrease as the temperatures increased.

At the Trona Airport event, vBox logs were collected on our customer's car with ESS VT1-535. In addition to the vBox data collected at the site, data logs were also collected for ambient temperature, ambient pressure, and density altitude. The Trona Airport event wasnt the only available data set for this car. A year prior, the cars owner ran a series of six back-to-back 0-130 MPH tests to capture 1/4 mile times along with 60-130 MPH results. These tests were performed in San Jose in hotter conditions than the Trona Airport event. Although the San Jose tests werent intended to be a heat soak test, they were exactly the same types of tests one would conduct if testing heat soak on a non-intercooled application.

Both data sets contained a collection of vBox data, along with data logs of the cars vital statistics (timing, air-fuel ratio, etc.) via a CAN bus connection, and weather data. If heat soak was affecting the results, we would expect vBox performance to decrease as the car was run back-to-back-to-back without a cool-down. Or in the case of the Trona Airport event, vBox performance would decrease as the ambient temperatures increased. But thats not what happened. For both sets of data, the cars fastest runs came after the temperatures were the hottest. These results are significant especially for the San Jose tests, because all six tests were performed back-to-back-to-back without a cool down exactly what you would want if you were performing a heat-soak test. But without IAT data, all of the evidence is still nothing but circumstantial. Clearly more tests were needed.

Testing Heat Soak

If I was going to conduct a heat soak test, I wanted the tests to be exhaustive and conclusive. I wasnt content to run six back-to-back tests, this time I wanted ten tests. I wanted ten tests with little or no cool down between them. I wanted to run them on a day with reasonably hot temperatures (80+ degrees). Then finally, I wanted to let the car sit for 10 minutes baking in the sun on the pavement while idling before the tenth and final run. This is what I considered a difficult test; one that should expose the effects of heat soak if and when it occurs.

Just like the prior tests, each test should be conducted as 0-130 MPH. This would allow me to collect two test points at a time. Using this method, I was able to capture 1/4 mile drag racing results along with 60-130 MPH test data as well. All data would be submitted to www.perfdb.com for verification.

In these tests, Im employing three instruments to gather and collect data. The vBox collects GPS velocity and is the standard tool used by all performance enthusiasts. Ive connected a CAN bus analyzer to the cars PT-CAN bus. This is the computer data bus that carries the entire cars data traffic to and from the ECU. The CAN bus analyzer collects every byte broadcast to or from the cars ECU. This may sound like enough data, but it isnt. The cars ECU bus doesnt broadcast everything needed to test IAT; specifically it doesnt broadcast IAT itself. To get IAT data, we need to tap into another of the cars computer buses the D-CAN bus (Diagnostics CAN bus) to instruct the ECU to start broadcasting this data. Using a tool that connects to the D-CAN bus, the cars ECU is instructed to broadcast IAT data, spark advance, and Air-Fuel-Ratio data (AFR). This data is broadcast onto the PT-CAN bus, and allows me to capture it with the CAN bus analyzer.

The following pictures show the connection to the cars PT-CAN bus.







Using the instrumentation above, Im able to collect real-time data (as the car is running) for the following important items.

• Throttle position
• RPM
• IAT
• Ambient temperature
• Ambient air pressure
• Engine water temperature
• Engine oil temperature
• Ignition spark angle
• Air Fuel Ratio (AFR data)
• Timestamp data
• Gear selection
• GPS speed
• GPS height
• GPS timestamp
• ECU timestamp

Testing Heat Soak

I tried to run as many back-to-back tests as possible without any cool down. Even though I was running on an empty closed course road, I wanted at least 1/4 mile of space in front and behind me before I began each test. This would mean I would occasionally need to wait for a car to clear before I would test again.

The following chart shows the timestamp data for each test. Timestamp Start is sampled when the car began rolling. Timestamp Stop is sampled when the car stopped before the next test. Time between Starts is the difference between all timestamp starts. Time between tests is the cool down the difference between the car stopping and car starting again. The data below shows the average cool down at 37.6 seconds, with the shortest cool downs at 3.5, 3.8, 4.0, and 11.3 seconds.



The next chart shows the weather for each run. The temperatures ranged from 82 to 84 degrees, and the density altitude ranged from 2500 to 4000 ft.



This chart shows the engine temperature and IAT data. It is clear from the following data that engine oil, water, and intake air temperatures were all increasing substantially with each successive test.



The following chart shows performance test results along with the same IAT data above. The graphs below show the same test results with IAT and engine temperature as well.





Adjusted Results:

After I collected all of the data and started collating it, I realized another great use for the PT-CAN bus data that I had collected. Engine throttle position is data logged every 0.01 seconds (100 times per second). The clutch switch broadcasts a message on the CAN bus every time I press or release the clutch. This makes it possible to calculate my precise shift time by measuring the amount of time from lifting my foot from the gas pedal to shifting, releasing the clutch, and pressing the gas pedal down again. The vBox can give you a rough idea of shift time, but is only accurate to ± 0.1 seconds meaning the results could be off by as much as 0.2 seconds. Thats not too good when youre trying to measure something thats only 0.3 to 0.5 seconds long. But using the CAN bus data I collected, I can precisely measure of my shift times in each gear.

I can also use this data to eliminate the effects of my inconsistent shift speeds to see if the results change. Ideally, you would want to eliminate inconsistent shift speeds as they could mask the effects of heat soak. For example, its possible that a slow time might turn into a faster one relative to othersand visa-versa. Using this method, I was able to calculate the exact shift speed (+/- 0.01 seconds) and subtract it from the results.

The following chart shows a full break down of my shift speeds. The numbers in the chart are the timestamps on the PT-CAN bus data logs. The purpose is to measure the elapsed time from lifting my foot from the gas pedal, depressing the clutch, shifting, releasing the clutch, and pressing the gas pedal again.



Now that Ive collected the shift speed data, I can subtract it from my initial results to see if there are any effects of heat soak that are hiding behind my inconsistent shift speeds.





Conclusions:

In the end, I ran ten back-to-back-to-back tests on the same Alekshop customer car used at the Trona Airport competition and earlier San Jose performance tests. Four of the new tests were conducted with less than 12 seconds between them, and three of the tests were run with four seconds or less between them. The final test allowed the car to sit on the tarmac idling for ten minutes directly in the sun on the pavement to simulate the effects that some people experienced at the Trona Airport event (this car was not allowed to sit and idle on the tarmac at Trona).

The results ended up nearly identical to the other two data sets. Not only was the VT1 quite resistant to the effects of the heat soak that I put it through, its fastest times came when the engine temperatures and IATs were the highest, and the car was going slightly uphill.

Acknowledgement:

The car used in all three data sets, including the Trona Airport event is an Alekshop customer car. The cars owner has been gracious to allow Alekshop to borrow the car for such competitions and granting access to test the cars performance and data log the results whenever the need arises.

VBox files and CAN bus data log files are available upon request.

[GIdriver]

Impressive!! Solid kit!

[Longboarder]

Great analysis. I was the one hoping it was heat soak. This conclusion may fundamentally change my opinion about buying a supercharger for my M3 now.

I was one of cars who ran against this M3 at the Trona Airstrip. My 335 is only lightly modded, and made right about 400 WHP on ESS' dynojet. I also have an auto transmission and my car is full weight (including 29 lb rear wheels). It's a far cry from a fast 335. Given the outcome of the race (a dead even tie), and also the fact that I have an M3 on order, I really wanted the supercharged M3 to not just beat my car, but put bus lengths on it. So when it didn't, I was hoping for an excuse/reason. Is there still an reason? This particular M3 dyno'd at 472 to the wheels. How could my 335 keep up? Effect of DA's on a supercharged car vs turbocharged car? Or is this just how fast (or slow) a 535 M3 is?

[sales@ESSTuning]

Originally Posted by Longboarder

Great analysis. I was the one hoping it was heat soak. This conclusion may fundamentally change my opinion about buying a supercharger for my M3 now.

I was one of cars who ran against this M3 at the Trona Airstrip. My 335 is only lightly modded, and made right about 400 WHP on ESS' dynojet. I also have an auto transmission and my car is full weight (including 29 lb rear wheels). It's a far cry from a fast 335. Given the outcome of the race (a dead even tie), and also the fact that I have an M3 on order, I really wanted the supercharged M3 to not just beat my car, but put bus lengths on it. So when it didn't, I was hoping for an excuse/reason. Is there still an reason? This particular M3 dyno'd at 472 to the wheels. How could my 335 keep up? Effect of DA's on a supercharged car vs turbocharged car? Or is this just how fast (or slow) a 535 M3 is?

Run a VT1-535 equipped car with DCT or a good driver

[GIdriver]

Originally Posted by Longboarder

Great analysis. I was the one hoping it was heat soak. This conclusion may fundamentally change my opinion about buying a supercharger for my M3 now.

I was one of cars who ran against this M3 at the Trona Airstrip. My 335 is only lightly modded, and made right about 400 WHP on ESS' dynojet. I also have an auto transmission and my car is full weight (including 29 lb rear wheels). It's a far cry from a fast 335. Given the outcome of the race (a dead even tie), and also the fact that I have an M3 on order, I really wanted the supercharged M3 to not just beat my car, but put bus lengths on it. So when it didn't, I was hoping for an excuse/reason. Is there still an reason? This particular M3 dyno'd at 472 to the wheels. How could my 335 keep up? Effect of DA's on a supercharged car vs turbocharged car? Or is this just how fast (or slow) a 535 M3 is?

Good question. I was wondering the same.

[GIdriver]

Originally Posted by Roman@ESS

Run a VT1-535 equipped car with DCT or a good driver

Good answer. LOL!!

[CBS]

Wow! Awesome information, thank you OP for your post.

Great Kit!

[Longboarder]

Originally Posted by Roman@ESS

Run a VT1-535 equipped car with DCT or a good driver

How about tomorrow afternoon at Willow?

I really hope you put a few bus lengths on me. Let's start around 30-35mph. That's the speed we started at Trona. Please make me a believer.

[jeff@autocouture]

Never had one issue with my 535, amazing reliability!

[GIdriver]

Originally Posted by Longboarder

How about tomorrow afternoon at Willow?

I really hope you put a few bus lengths on me. Let's start around 30-35mph. That's the speed we started at Trona. Please make me a believer.

If it happens let us know how it goes. Intrested in this kit too.

[Longboarder]

And I'm not buying the 6MT excuse. Last night I got a ride in Malek's 6MT with just tune + exhaust and that thing flies.

[GIdriver]

Originally Posted by Longboarder

And I'm not buying the 6MT excuse. Last night I got a ride in Malek's 6MT with just tune + exhaust and that thing flies.

DCT does make a difference. The question is how much. The truth is that with a ~70whp advantage one would expect that the 535 would win. The other variable is the driver.

[sales@ESSTuning]

Originally Posted by Longboarder

And I'm not buying the 6MT excuse. Last night I got a ride in Malek's 6MT with just tune + exhaust and that thing flies.

If you are making 400 whp an additional 60-70 whp more will not result in several bus lengths in a 50-140 mph rolling run but you will get beat, by how much depends on factors including driver ability. If you want a bigger seperation from yuor current setup simply run a 600 or 625 kit which make 510-550 whp.

[Longboarder]

Originally Posted by Roman@ESS

If you are making 400 whp an additional 60-70 whp more will not result in several bus lengths in a 50-140 mph rolling run but you will get beat, by how much depends on factors including driver ability.

Agree. That's why the tie against the 472 RWHP 6MT ESS 535 M3 is so odd, and I was looking for reasons why this could occur. Could a DCT really make that much of a difference? Another thing...is there an advantage of a 535 kit over a full-bolt on + meth M3? The ladder would be much cheaper. I'd really like to see this match up.

[THE-FN-MAN]

DCT makes a huge difference man. Huge....

[m33]

DCT makes a world of A Difference especially down low , race the 6mt up top and things will change

[Hershey]

Aleks- you are the man!! You are really making it hard for me to say "No" towards an ESS kit!

[Blotman]

Originally Posted by THE-FN-MAN

DCT makes a huge difference man. Huge....

Having my VT1-535 MT6 going head-to-head with stock DCT on the track before on a few occasions, I can attest to this. On long straightaways, sure I'll pull ahead once I get into 4th gear. But on the rest of the track where I'm rowing between 3rd and 4th, and sometimes down to 2nd, I lose a lot of ground. You may be able to blame the driver, but I don't believe I suck that bad that an extra 100+ hp couldn't make up for it.

[M3_WC]

Originally Posted by Longboarder

Agree. That's why the tie against the 472 RWHP 6MT ESS 535 M3 is so odd, and I was looking for reasons why this could occur. Could a DCT really make that much of a difference? Another thing...is there an advantage of a 535 kit over a full-bolt on + meth M3? The ladder would be much cheaper. I'd really like to see this match up.

DCT is quicker, but it really depends on the driver in the manual M3. I do think the difference is a bit blow out of proportion sometimes.

5 runs - 2011 M3 manual vs 2011 M3 DCT

[Bob MG]

Alex you're a champ

You have two prefaces in your thread though

[Krozi]

Great write-up!

[IMG]

LONGBOARDER
Your car is an Auto and doesn't drop boost between gears. So basically you are constantly making boost and in a strong power band .
A fair run would be against a DCT and you will lose, your low end TQ will help you but not till the M starts getting in the high RPMs.