Official top speed of Sonic RS

[Dirt55]

Does putting a tune on your car get rid off governor? All the cars here that have reached these speeds, as I recall, have tune? Just playing detective to your idea.

As for the rpm idea. I have had it further to where is does hit a limiter. It was a little past 6500. I think I was doing that in 3rd gear though.

I am not too concerned about going faster than 130 though. I think this car is way more fun zipping through the canyons here.

Sent from my SM-N9005 using Tapatalk

 

[ahtoxa]

I doubt there is a governor per se... I mean it's possible, but I doubt it. Others have posted about reaching speeds of 140+, and we've seen pics of cars on a dyno that were doing in excess of 170. Not that the car will ever reach that speed due to drag, but that means the ECU won't stop it.

I'm guessing what you reached was top allowed RPMs, although that would be a little higher than the 5900 you estimated

Or maybe they decided RS drivers would actually try to drive fast, so they bothered to put a governor on while us lowly LT owners don't need one?

I think there is a governor, at least with the stock tune. I know that aftermarket tunes can remove it. While I don't know for sure with the Sonic, I do know that other manufacturers have a limiter that's set not to exceed the rating of the factory tires they put on that vehicle. In the case of the Sonic, the 15's are rated "H" at 130 mph.

Due to potential legal liability (I'm sure GM is well aware of people modifying cars and especially turbo cards), I doubt GM would let the vehicle exceed the tire ratings.

Now, if the governor was removed via aftermarket tune, then GM can waive all their responsibility at that point.

 

[laborsmith]

RPM seems to be limited particularly in first gear.

I have never seen a post by either Vince (Trifecta Performance) or Brian (VTuners) that indicated the existence of a speed governor.


Laborsmith

 

[ahtoxa]

There's a post in the following link by a member, who claims to have a ticket with Trifecta to remove the governor and they say they will not remove it due to tire rating. True or not, I don't know.

http://www.sonicownersforum.com/forum/bad-news-racing/5306-maximum-speed-2.html

 

[austinw24]

I volunteer to do it again and data log it if Vince agrees to post up some numbers based on what's available with data logging. In particular, rpm, speed, engine load, and whatever anyone else can think of.

 

[Eyeflyistheeye]

I'm really surprised GM limits the car to 130 on "H" rated tires since most manufacturers build in a margin of safety to the ratings of the stock tires versus the theoretical top speed of the car. The Camaro LS has a speed limiter that cuts in at 118 on its "H" rated tires, and the Legacy GT I used to own has a speed limiter that cut in at 150 on tires rated for 168 mph.

I've been 115 in my Sonic and with the dynamics of a tall supermini, I have no desire to go any faster in it.

 

[Dirt55]

Holy sh*t that was a long time at WOT! I'll bet the primary catalyst was HOT!

Maybe I should get rid of it.

 

[ShadowRS]

Surprised the damn thing hit 110.

 

[BSD]

Maybe I should get rid of it.

That sounds like an excellent idea. Did you take a look at MPFab's anaconda? (pun intended - http://www.sonicownersforum.com/for...tion/9798-small-batch-anacondas-ready-go.html) I think it would go nicely with your future magnaflow.

Okay, mayyybe I just want you to get it so I can borrow it and see if it has any more power than my ZZP down/midpipe. :banana:

 

[Dirt55]

Just wanted to through this out there. I didn't create this video to disprove anyone. I merely wanted to see the limits of my car while it is stock.

My goal was to hit redline (6500 rpm's) in 6th gear and see how fast it was going at that point.

Here is the facts. At 131 mph my car experienced a drop in power. Best way to describe it, it was kinda like quick short bursts or sputtering effect. I did not let up on the pedal when I hit 131. It stayed "floored: for a few seconds after I hit 131. I left off just a tad then floored it again. The SECOND time I hit 131, the power started to "sputter" again. After that I came to the conclusion that the Computer, or whatever, was limited my speed. My RPM's were right around 5900. (I am guessing on that one, but did look that the tack just a bit earlier, so this is an educated guess, but I don't think I am far off).

Second fact is that I could have gone faster than 131 if it weren't for this sudden drop in power. I was maintaining descent acceleration before drop. I was actually thinking I could get to at least 135. All this is shown in the video. I did not fake or alter anything. I even had another member BSD in the car with me.

Also Just wanted to add that I have had the engine to redline (6500 rpm's) before in a lower gear. So on this day I filmed and not getting my engine to that speed, I have to conclude that there is a speed limiter on the car.

So having still having descent engine power at 130 then a sudden drop at 131, I highly doubt the "drag" on my car is so precise that 1 mph more would cause my car to not be able accelerate any more. If I still could feel the power and it just could not go any faster, then I would believe the "drag" theory.

Eventually I will get a tune, when I do, I will try this again and see if possible to go faster.

Again not trying to disprove what other people believe, my video is posted, as Ripley would say...Believe it or not!

 

[laborsmith]

Chevy says the turbocharged Sonic's speed is drag limited. Chevy is not shy about stating when there is another form of speed governing, so in this situation I go with Chevy.

That does not mean anything in your post is wrong, other than your conclusion. But nothing in your post leads me to believe Chevy is wrong. It seems to me that road conditions, wind speed and direction will have as great an effect on vehicle top speed as the gearing and the power.

But I am a social worker not an engineer so perhaps the forum engineers can shed some light.


Laborsmith

 

[Dirt55]

Well I think we can both agree to disagree. If, as I approached my max speed, I could feel the power getting less and less at a constant rate equivalent to my rate of gaining speed, then I would totally believe that my top speed was drag limited to 131 mph. BUT it wasn't, I felt a sudden drop in power--you do not feel sudden drops like that due to wind resistance unless you were driving into a tornado. It was a calm day, hence why it took me so long to do this, I was waiting for weather conditions to be good.

Furthermore, if it was drag limited, it would be possible to hit 132-133 if the wind just changed slightly. However, Two times I tried were exactly the same. The power drop precisely at the same time. If I was truly at the drag limit, it would have been reach at a slightly different speed- who knows, I could have encountered a slight cross wind. But by the fact that the power dropped precisely at that same point both times, it would conclude that a constant variable like the wind was not a factor.

Plus look at the video, I was relaxed, driving with one hand. The car was handling that speed with ease. It did not act like it was on the verge of losing control at all. It was holding the road very well. If I were at the drag limit, the car would have felt unstable and swirly on the road.

I could tell at 130 that I still had enough power to go faster, it was not reaching its breaking point naturally.

I have already proved Chevy wrong as they have stated top speed is 125, and I just proved that wrong by going faster than that. But if you want to go ahead and just believe whatever Chevy/people tell you without getting proof or finding out for yourself- more power to ya.

But I like I said, I created this so I could see for myself what the limit was, and I found it.

 

[Dirt55]

Well I just posted this to show everyone what the RS could do stock, not to be belittled and told I have no clue about what is going on with my own car while I am driving it.

This will probably stop me from posting further things I find out while I am over here and have access to road with unlimited speeds. I don't feel like being ridiculed for sharing things that I feel will help out with knowledge about these cars. It is people like this, that I am sure cause others to hesitate to share what they know if fear of being mocked.

 

[laborsmith]

Well . . . excuse me for offending any sensibilities. Not a first for me and likely not a last.


Laborsmith

 

[ScarabEpic22]

Too bad you cant turn the speed limiter off and see if it reacts the same way, I know exactly what you are describing. I havent had a need or reason to go that fast in my Sonic yet, but in my other GM vehicles thats what the speed limiter felt like (none except my Sonic have limiters anymore). The ECM is either pulling spark, shutting fuel off, or closing the throttle depending on which method GM went with for these engines.

Ive mentioned it in other threads, but the stock tune (manual trans) has the speed limiter set to use the CAN/GMLAN as it's source. I.e. the ECM doesnt have final say over the speed limiter, another module (EBCM probably) has the limiter. Easiest way to set the limiter is to change the source to ECM and set it how you want in HPTuners/EFILive.

 

[angus]

Well I just posted this to show everyone what the RS could do stock, not to be belittled and told I have no clue about what is going on with my own car while I am driving it.

This will probably stop me from posting further things I find out while I am over here and have access to road with unlimited speeds. I don't feel like being ridiculed for sharing things that I feel will help out with knowledge about these cars. It is people like this, that I am sure cause others to hesitate to share what they know if fear of being mocked.

Don't let the vocal minority dissuade you, most of us enjoy your post. This is the internet, and everything thing posted is subject to ridicule. I got lambasted on here for posting my bike rack, but what I found funny my biggest critics have never seen or used a rack like mine, yet they thought they knew everything and even though I have used the rack for over a year they totally tried discount my review.

So just keep on keeping on, enjoy your car, enjoy the Autobahn ( I know I would) and look forward to reading more of your adventures.....

 

[NR552]

Before any further back and forth banter, I respect that the deed was done. Truly, 131 is hailing the mail in such a small car. Also, GM doesn't speed limit vehicles, they DO though limit RPM in certain gears (6500 RPM 1, 2, 3, 4, 5, 5900 RPM 6th) sorta thing. It's done for many vehicles that way. So technically it's not a speed limiter, it's an RPM limiter. I had this happen in a Dodge Dakota (112-113 MPH in OD, stock programming)... It lost power exactly as the 131 mph Sonic run. In that Dakota, you could bypass the stock limiter by turning the ignition key (it won't engage the starter, but it did drop all speed sensors/RPM would drop to ZERO)... and you left the key forward (start) during this time frame. If you let the key return to run, the engine would misfire/die until below about 110. Later, with a custom program I was never able to get the limiter (because it was pushed out to 199 mph). I was RPM limited (6000 rpm, in OD) at 156 MPH (+- 3-4 mph due to GPS accuracy). Needless to say, the video proved 131, and that's plenty for ANYONE.

 

[Dirt55]

If that is true, then it would be right. I was right around 5900 rpms, give or take, when I hit 131. I was hoping my gps would have shown up better to see what it said my speed was. The cutting of power did feel awfully close to when you just press on the gas in neutral and let the governor kick in at redline.

What was irritating me was people calling me a liar, saying I doctored the video, being told I didn't know what I was talking about. What happened on the video had nothing to do with "drag limited". You don't feel a lose in power from that.

But if the car is rpm limited at 5900, then it makes perfect sense. But next question-- why is it limited at 5900 when red line is 6500?

Sent from my SM-N9005 using Tapatalk

 

[sx sonic]

I really don't think anyone is calling you a liar. We're all trying to figure out what's going on with the limiter.

In all of my runs (stock=127, 129, 127.. tuned=137, 145, 140) it felt like I couldn't go any faster. There was no loss in power, just an end to speed increases. Which would be the drag limit, which essentially means the engine does not have enough power to overcome wind resistance. Also the car will not handle any differently at the drag limit than it would 10 mph slower or 5 mph faster, It's easy to think that at 1st because of the terminology but remember all it really means is you need moar power to go moar faster.

Now you've added 2 variables that could very well be the reason you feel a drop in power instead of a lack of speed increase. You're going 2 mph faster than me when I was stock so there could be a speed limiter that you reached and I didn't. You're also in 6th and at higher RPM than I was with the LT. As another poster commented there could be an RPM limiter that you hit.

I've heard it mentioned that there's a "soft RPM limiter" that changes spark and/or fueling a bit before the normal rev limiter is hit, slowing the rev increases down by reducing power. I'm not sure how true that is but I do recall the stock tune revving slower from 6k to 6.5k rpm than it did from 5.5k to 6k. It's possible that's what you felt.


Need more testing

 

[Dirt55]

well apparently there is a post that was removed.

Anyway, yes, I know what it feels like when a car just doesn't have enough power to just go faster. Plus I know what it feels like when the engine just suddenly loses power. The case here is the engine just suddenly lost power. I don't get why this is so hard for people to believe? It's on film, I didn't fake it.
I guess the only thing I could do more for people to believe me is film my foot on the gas the pedal to prove I wasn't letting off the gas.

Only reason know I might think it might be rpm limited is the post a few posts up that states in 6th gear, the car is rpm limited at 5900. That never crossed my mind cause I didn't think there would be an rpm limiter that would kick in before redline.

I have also been in cars when reaching the threash hold of what it can do aerodynamically. You do feel it starting to lose control a little cause the wind is actually pushing it. Hence why sport cars have a fin that helps keep the rear tires pushed down at higher speeds. Anyway, while doing this, I could feel that that car had more power left to get it to go faster, not much more, but more. but I will say this again, there was a drop in power, like something that was taking power away, not slightly, but a lot.

But yes I was being told those things about lying, faking etc.., in this thread and others. Someone deleted their posts in between mine.

I guess the only way to prove this is by getting more HP without doing a tune. Trying it again, and seeing if the engine cuts out again at 131 mph, (or 5900 rpm's in 6th gear) or whatever. But I have a feeling if I did all that, people will give me **** for whatever I post too.

I wasn't trying to prove anybody wrong or anything, just wanted to see what the car could do and thought I would film it to give others on here more of an insight about the car. Share the knowledge, not be belittled by saying I don't know what I am talking about.