Supercharged vs NA at the track Part 2. (Results are shocking)

[CSMRX7]

I have to admit that my experiences are very different. A little background, I have over 10,000 laps at my local track, where I was an instructor (which closed last summer ). I have done probably 600 laps in an NA M3 and probably 1100 laps in a SC E90 (575 and 625 kits) on this track. I never had any overheating issues, although our ambient temps way up North are lower than California.

I have been able to do much better laps with the SC. I saw appeciably higher speeds on both the front and back straight with front straight speeds increasing by 30kph on the front straight. The only place I saw any slower times was on the entry to the front straight that was a 2nd gear turn, so traction is an issue here with street tires. On r-compounds this was not a problem, so beyond requiring early braking points I didn't see any deterioration of lap times.

[radiantm3]

Originally Posted by CSMRX7

I have to admit that my experiences are very different. A little background, I have over 10,000 laps at my local track, where I was an instructor (which closed last summer ). I have done probably 600 laps in an NA M3 and probably 1100 laps in a SC E90 (575 and 625 kits) on this track. I never had any overheating issues, although our ambient temps way up North are lower than California.

I have been able to do much better laps with the SC. I saw appeciably higher speeds on both the front and back straight with front straight speeds increasing by 30kph on the front straight. The only place I saw any slower times was on the entry to the front straight that was a 2nd gear turn, so traction is an issue here with street tires. On r-compounds this was not a problem, so beyond requiring early braking points I didn't see any deterioration of lap times.

Are you 6MT or DCT? Both of the 600 kit cars I know are DCT. Not sure that has anything to do with it, but just curious. Regardless, I'm glad the intercooled kits are performing well for you guys. I guess there aren't many guys with 535 kits doing many track days. I'd love to hear more from those guys.

[CSMRX7]

Originally Posted by radiantm3

Are you 6MT or DCT? Both of the 600 kit cars I know are DCT. Not sure that has anything to do with it, but just curious.

6MT Also my comments are based on a pretty fast track average speed over 90mph.

More 2nd gear turns would likely bring the results much closer.

[Gearhead999s]

Originally Posted by CSMRX7

I have to admit that my experiences are very different. A little background, I have over 10,000 laps at my local track, where I was an instructor (which closed last summer ). I have done probably 600 laps in an NA M3 and probably 1100 laps in a SC E90 (575 and 625 kits) on this track. I never had any overheating issues, although our ambient temps way up North are lower than California.

I have been able to do much better laps with the SC. I saw appeciably higher speeds on both the front and back straight with front straight speeds increasing by 30kph on the front straight. The only place I saw any slower times was on the entry to the front straight that was a 2nd gear turn, so traction is an issue here with street tires. On r-compounds this was not a problem, so beyond requiring early braking points I didn't see any deterioration of lap times.

You were also at about 3500 asl so of of course a FI engine will maintain its power compared to a NA engine which will have a loss of 3% per 1000 ft per altitude increase.Your increase compared to stock will be much greater than someone who operates much closer to a sea level pressure altitude like Laguna Seca.

[paradocs98]

Originally Posted by radiantm3

Are you 6MT or DCT? Both of the 600 kit cars I know are DCT. Not sure that has anything to do with it, but just curious. Regardless, I'm glad the intercooled kits are performing well for you guys. I guess there aren't many guys with 535 kits doing many track days. I'd love to hear more from those guys.

First of all--impressive driving and lap times for only having 16 track days under your belt.

Your data overlay is informative. While you achieved a slightly higher max speed at several points on the track with the supercharger setup, you consistently maintained higher speeds through the slow sections/corners with the naturally aspirated setup. Maybe this has to do with what you mentioned earlier--that throttle response feels more linear and easier to modulate with the NA setup--so it's easier to maintain momentum in those slow sections. The supercharger runs look more point-n-squirt in nature. (This is just my guess at interpreting your data. I'm by no means a pro, either, only having 25 or so track days under my belt.)

Forum member arter is running an ESS 535 supercharger on his M3 and he frequents the track. Maybe he can offer some of his insights as well.

[CSMRX7]

Originally Posted by Gearhead999s

You were also at about 3500 asl so of of course a FI engine will maintain its power compared to a NA engine which will have a loss of 2% per 1000 ft per altitude increase.Your increase compared to stock will be much greater than someone who operates much closer to a sea level pressure altitude like Laguna Seca.

Superchargers don't compensate for altitude like a turbo. They are pulley driven, so if pulley size is the same the boost pressure is the same. Unlike turbos which are controlled by wastegate which will maintain a constant absolute pressure and compensate for the thinner air of altitude.

This is of course a massive simplification, as we assume no efficiency losses as the turbo runs hotter (ideal compressor map) and the altitude also reduces spool time for turbos. But the point is the SC don't see the sme benefits as TC.

[Gearhead999s]

Originally Posted by CSMRX7

Superchargers don't compensate for altitude like a turbo. They are pulley driven, so if pulley size is the same the boost pressure is the same. Unlike turbos which are controlled by wastegate which will maintain a constant absolute pressure and compensate for the thinner air of altitude.

This is of course a massive simplification, as we assume no efficiency losses as the turbo runs hotter (ideal compressor map) and the altitude also reduces spool time for turbos. But the point is the SC don't see the sme benefits as TC.

Do these superchargers not have a bypass valve which is effectively the maximum manifold pressure control?If I remember properly these are are controlled by the ECU to control boost when the throttle is closed & maximum boost level which is also determined by pulley size.I have not owned a S/C car in over 20 years so maybe this is all an out of date technology.

[CSMRX7]

Originally Posted by Gearhead999s

Do these superchargers not have a bypass valve which is effectively the maximum manifold pressure control?If I remember properly these are are controlled by the ECU to control boost when the throttle is closed & maximum boost level which is also determined by pulley size.I have not owned a S/C car in over 20 years so maybe this is all an out of date technology.

The bypass valve is vacuum operated so it dumps boost when the throttle is closed like a BOV.

[Longboarder]

Originally Posted by radiantm3

I wouldn't mind living with it if the only issue for me was stock power at the track. The slight decrease in throttle response, extra weight, and affected linear power band were my primary issues. The fact that I ran just as fast a time without the kit only validated that removing the kit was the right thing for me to do. Many people suggested a water/meth kit, but I shouldn't have to do that. I was going to upgrade to the intercooler, but it blocks the oil cooler which causes the engine temps to rise. I've seen it happen over and over on more than one car. I have no idea how you aren't having the issue. Maybe it's the weather in your area or maybe you just aren't driving hard enough at the track?

I don't get why people think I made a big mistake one way or another. If you read about superchargers on these forums all you hear is complete praise aside from the fact that you void your engine/power train warranty. I was well aware of potential heat soak of a non-intercooled kit at the track. I did my research. In fact, I stated before I even purchased the kit that I would be happy if I had more power on the street and stock power at the track. I want my car to run safely and that's exactly what it did.

I got a good deal on the kit and put a good 10k miles with the supercharger on the car. I loved it on the street, but didn't care for it at the track. I learned a lot from the experience. Now I get to sell my kit to someone looking to give it a shot for a good deal as well. I'm 100% glad that I got to experience my car with a supercharger and I'm also 100% happy that it's off the car now. I'm not a fanboy and I'm not jumping on any bandwagons on this forum. I like experiencing and learning about things for myself.

I get what you are saying and frankly I would have never done a supercharger myself if I was looking for primarily a daily driven track car. Just given that you had the 535 kit already, I recommended something (water/meth kit) that could have given your full power back on the track. Maybe you wouldn't have improved your track times with the the water/meth kit initially but it would seem illogical that you couldn't turn a better track time eventually with possibly 50-75 more HP.

[Porschefile]

Running 25% faster through the slowest portion of the track was not solely a mechanical thing resulting from the supercharger removal. You could have gone just as quick through the slowest corner with the blower, so the data is flawed. My guess is that you felt more comfortable in the slow section with less torque, but you can't blame the car for that. I agree power mods are overrated on track, but you can't say that it is slower just because one driver on one track was slower.

Good times though.

[Bubbles]

Thanks for sharing. Interesting result.

[klammer]

Thanks OP for sharing and some interesting discussions on here. I can't imagine more power making one slower, but could see it making ME slower. I mean, it's a pretty powerful car as is, i'd rather get a square setup instead of the SC which would probably have the same effect for me I'm just too afraid of the reliability factor as I think I push my car about as far as she'll go... Good thread

[radiantm3]

Originally Posted by klammer

Thanks OP for sharing and some interesting discussions on here. I can't imagine more power making one slower, but could see it making ME slower. I mean, it's a pretty powerful car as is, i'd rather get a square setup instead of the SC which would probably have the same effect for me I'm just too afraid of the reliability factor as I think I push my car about as far as she'll go... Good thread

What kind of camber are you running? I don't think I'd benefit from a square setup (aside from being able to rotate tires). My suspension is set up fairly aggressive for a dual purpose car and I have very little understeer issues. Right now it's super neutral and I can get it to oversteer at will.

[klammer]

Think I'm about -2.2 or so. Just have the Dinan fixed plates. Been running a 265/295 stagger for a bit (over 50 days) and think the square setup would have as much of a change on driving dynamics as a 575 or higher kit with my stagger. I'm carefully trying to sway the law of avg's in my favor (as the days rack up and this is my wifes DD) by doing things like that to keep a somewhat safer car on track rather than set absolute fastest times at this point, hence streets over R-comps, the stagger, suspension setup, etc. These are some of the ways I balance the risk at the track and one of those is going NA over FI. I know it may just be placebo, but in case y'all didn't know, the placebo effect is real.... At least for me

[arter]

Okay, I will pop in with a " I am, happy with my VT1-535 on the tracK".

I am running 10 - 15 mph faster on straights with the S/C and overall a couple of seconds faster on the same tracks than when I was just NA.
Ran the first year with the car NA ( 14 days)and then last year SC'ed ( 16 days).

Added the M24 oil cooler so my engine temperatures with the SC are actually running 20 F cooler at the end of track days than when I was NA.
I can't get the oil over 245 now ( first year often hit 270F and got the temp light several times). Same track, same summer temps...

Inter coolers cool the charge air, but are usually placed in a position where they block the flow to the radiator. So the engine doesn't necessarily run cooler. I agree that the inter cooler will produce more power of course....

Now I also run in the North East, but it has been in the mid 80's many days and I haven't had an over-heating problem.


I hit 160 mph on the back straight of VIR with the 535, so I don't think I need more power, just to become a better driver.

[Richard@M-World]

I had the chance to look at Mark's Solo DL data... as well as work with a few customers with supercharged M3s.

I think everyone can agree that a supercharged car undoubtedly offers more performance. But whether this performance is readily accessible can vary depending on the driver.

When it comes to power, more is better . However, sometimes having too much power makes a car harder to drive, hindering the achievable lap time.

"Power is nothing without control." -Pirelli

[joe@trinityautosport]

OP thanks for sharing! Great times! 6/29/12 @ Laguna Seca I did the same time 1:44.5 NA and I'm hoping to go back this year and see what I can do with the VF20 kit

[bigjae1976]

A couple of things.

First, hardware. Supercharges add weight over and in front of the front axle. So the balance of the car changes. Not a big deal on the street but it does make a difference on the track.

My stock M3 will pull redline in 100 degree temps. I can't imagine how the engine is NOT pulling timing after about 10 minutes in the first session and not badly heatsoaked by the end of the day, intercooled or not. Case in point with my FI'd 330. My fastest lap in my 330 is consistently the first session of the day. I feel a HUGE difference in power when it starts mid 50's in the morning and gets to the mid 70's. I'm talking about probably a 10%-20% difference in some cases.

I think its a good guess that your DME is dumping fuel and pulling timing to save the engine because you have some detonation from heatsoak. Forget AFRs, they can be misleading. I'd log timing, fuel trims, and knock sensors. I've been doing a lot of research and learned quite a bit about FI and tuning with the recent maladies with my 330. Typically, what most companies do is add fuel and pull timing when the knock sensors detect detonation. Basically relying on the engine's DME to save your engine. When you add MORE fuel, you compound the issue. To a point, the unburnt fuel in the combustion chamber can be cooled by the "cool" spots (anything metal -cylinder walls, piston head, etc). So it gets expelled through the exhaust. You run into problems when the unburnt fuel is suspended in free air away from the cool spots. It heats up and detonates. Knock sensors go off. DME adds more fuel. More unburnt fuel is suspended in free air away from the cool spots. It heats up and detonates. Knock sensors go off. DME adds more fuel. More unburnt fuel is suspended in free air away from the cool spots. All the while, your AFRs will read rich and "safe".

In your case, the engine is still within a good spec for the piston to valve clearance which goes a long way to prevent detonation but its still not good to rely on knock sensors...if that's what is happening. In my case my engine builder sucked. There was too much clearance between the piston head and valves because they used a ghetto ass thicker head gasket. So my car was leaning on the knock sensors by the 3rd session, felt totally gutless by the 4th session. This increased the harmonics in the rotating assembly which vibrated my VAC oil pump shaft loose in 5 months.

I'm willing to bet that's what is going on inside of your engine at the track. If you did a post track dyno, I'd bet that you are below stock power levels.

[SP33DRCR]

Hey Mark, impressive lap times indeed. I was actually at Laguna that day as well--in the green run group. My best was a 1:47.9, tho it was only my third day driving that track. Hopefully I'll join you down in the 44's before too long

In terms of this thread, I think that bigjae may be on the right path. If you were to have dyno'd the engine with the bolt-on SC, you likely would have found that you are actually not getting much additional power in a track setting (compared to, for example, street driving situation, which is a lot different). The data you provided actually confirms this. If you were getting, say, net 100hp more with the supercharger at the track, your speed down the two straights would be higher--a lot higher. That's just simple math. But it isn't. (I agree that track surface conditions and ambient temperature/humidity may play a role, but it would be small and thus inconsequential.)

I know nothing about the particular supercharger you used, or what other mods were done to accomodate the supercharger. But I think the conclusion here is that the supercharger, as installed, wasn't designed/setup for track use. Sounds like the basic issue is heat. Running with it on your car at a track when it is not performing optimally could slow you down. It is adding a 40lb lump at pretty bad location (up high, and in front of the front wheels), it will drag on the engine just like running the A/C, and it could affect the stock throttle responsiveness (which is one of the great attributes of the car), & etc. That may actually explain why your lowest low speed is actually with the supercharger on the car.

So I guess I don't find the results to be all that shocking--I'd sort of expect it.

[llis]

Just curious, how much weight does the SC add? With that added weight up front, how much is your corner balance affected? I would imagine adding weight under the hood would exacerbate understeer -- could that have been a contributor to the slower corners? Wouldn't adding that weight require some front-end suspension adjustments?

[radiantm3]

Originally Posted by llis

Just curious, how much weight does the SC add? With that added weight up front, how much is your corner balance affected? I would imagine adding weight under the hood would exacerbate understeer -- could that have been a contributor to the slower corners? Wouldn't adding that weight require some front-end suspension adjustments?

I've heard 40lbs? But I don't have under steer issues and I'm corner balanced if that makes any difference.

[Longboarder]

Originally Posted by SP33DRCR

If you were getting, say, net 100hp more with the supercharger at the track, your speed down the two straights would be higher--a lot higher. That's just simple math. But it isn't. (I agree that track surface conditions and ambient temperature/humidity may play a role, but it would be small and thus inconsequential.)

I know nothing about the particular supercharger you used, or what other mods were done to accomodate the supercharger. But I think the conclusion here is that the supercharger, as installed, wasn't designed/setup for track use. Sounds like the basic issue is heat. Running with it on your car at a track when it is not performing optimally could slow you down. It is adding a 40lb lump at pretty bad location (up high, and in front of the front wheels), it will drag on the engine just like running the A/C, and it could affect the stock throttle responsiveness (which is one of the great attributes of the car), & etc. That may actually explain why your lowest low speed is actually with the supercharger on the car.

So I guess I don't find the results to be all that shocking--I'd sort of expect it.

Agreed.

This is why the VT2 (intercooled kit) would be much more beneficial because no matter if it's lap 1 or lap 40, you are running cool and timing is not being pulled (at least with my experience in analyzing my VBox data for 2 different track days).

I understand what radiantm3 is saying regarding the FMIC (component of the air to water system) in the VT2 that partially blocks the oil cooler but I'm actually seeing cooler oil temps on the track compared to the street given the constant airflow in a track situation...but I haven't tracked in the summer yet.