Why is my SD so FAST? - Page 3 - PeachParts Mercedes-Benz Forum

TwitchKitty · #31 06-01-2006, 11:01 PM

Occasionally a stock engine will perform far better than it was designed to. I have seen mediocre little *****box cars that would peel the tread off of tires and lame little motorcycles that would dump you on your back.

I got my hands on a couple examples and checked the tuning, etc to see if I could duplicate the performance with another example of the same vehicle, couldn't. I really would love to know why but some engines are much snappier than others that are supposed to be identical.

The example in this thread seems extreme but over the years I have learned to almost never say that anything is impossible when I haven't witnessed it personally.

sixto · #32 06-01-2006, 11:21 PM

I'm not so sure about G-tech accuracy. Folks I know who've tried to be scientific in comparing G-tech results to track and dyno results consistently showed that G-tech results are optimistic. But a G-tech is a heck of a lot cheaper and easier than a full-on tuning regimen. At boost level A the G-tech says 10 seconds, at boost level B the G-tech says 9 seconds. The difference tells me more than the absolute numbers.

The 10 second SD or 9 second SDL or 28 mpg 500SEL claims are difficult for me to believe. I'm not saying you're wrong, I'm saying I put stock in brainful of data that suggests these claims are beyond what I consider to be an acceptable range of variance. Are there anomalies out there? No doubt. What I have to decide is whether the anomaly is your car's state of tune or your methods. I don't have enough information to make a call.

Sixto

sixto · #33 06-01-2006, 11:26 PM

No, no, no, Hattie. The R in RIV is reference. It's just convenient to have the IP timing lug point towards the hole at 14-15 ATDC. Start of delivery is a set number of degrees from RIV so it's an acceptable way to set IP timing. Start of delivery is usually in the 24-27 BTDC range. It has to be BTDC or the fuel squirt will come too late in the power stroke for there to be a power stroke.

Sixto

pmckechnie · #34 06-02-2006, 07:28 AM

Sixto,
I sometimes feel sorry for these people that can only say "impossible","your lying", "can't be", etc. In how many cases does it happen that if they has said "I don't understand how that can be, could you tell me more?" If they would they may learn something from others that have spent a lifetime learning things. I have been working on cars for about 50 years now, and I believe I have learned at least something. My 500SEL has gotten 28.9 average mileage going from NC to Flordia. This was 99.9% hiway, cruse set at 80 most of the time, with extensive tuning for MPG only. It had a very poor idle, and little low speed power. It ran like gang busters above about 50. 0 to 60 was probably 15 sec which is terrible for a 500SEL. I sense have tuned it back for overall drivablity and it is a joy to drive. Same trip to Fl after seting it back to (Normal) got 22.1 which is still good in my opion.
If people would just listen to others and ask how, they may learn something useful.
When I was 16 my Father was probably the dumbest man I knew. When I was 50 he knew more than i will ever know. When he passed away, he was the smartest man ever. Actually, he was always the smartest man ever and over those many years one thing he taught me was "listen, you may learn something" and he was right as usual.
Now if there is anyone that would like to know how to get 29+ MPG from a 500SEL or probably most any car, let me know and maybe I will give away some of the knowledge I have gained over the years. But if you say "Stop lying" or something to that effect, forget it.

tangofox007 · #35 06-02-2006, 11:32 AM

Quote:

Originally Posted by Hatterasguy

As far as I can tell, those numbers are the start of delivery, thats what the RIV light indicates.

Does it make any sense at all that the start of delivery would vary by 39 degrees (24 degrees BTDC - 15 degrees ATDC), depending on the timing method being employed?

I suspect that a compression engine would be a little hard to start with the start of delivery occuring at 15 degrees ATDC!!!

vstech · #36 06-02-2006, 03:24 PM

Quote:

Originally Posted by Hatterasguy

125hp is 125hp, simply no way around that. Of course cars are not like computers and results may vary. Now if he said 11 seconds and his fuel and boost were turned up, maybe timing played with a bit, then I'd beleive it.

Your SDL is not stock, so of course that changes things. Plus 603's are up 25hp on the 617's, assuming everything is stock.

For example their is an argument that if you retard IP timing to 14ATDC on a 603 you might gain a bit. Mine is at 15ATDC, may or maynot knock another degree off that, I'll let the TC break in first.

So lets do this for this hot SD. What is your turbo putting out? What is the IP timing? What is the cam to crank timing? I am also assuming that your injectors have been checked and are in proper order. Valves adjusted goes without saying. What about the ALDA? Is the cap still on it or has it been played with? Can you get it on a dyno for some numbers?

Now most 617's I see have original injectors, never touched, timing never checked, ect. They are out of tune and tired, period.

I have not done much performance wise to the car at all. I have not even adjusted the valves since I got the car 5 years ago, but it has not been driven at all except for the last 3 months. and since then, all I have done is clean it up and work on the electrical parts that don't work.

I read several posts that said to do a 0-60 and when I did I was amazed, so I have done it a couple more times and unless I am a complete idiot with a stopwatch...(it is possible

) the worst time I have gotten is 10.14, I still have not gotten the GPS set up to verify the speedo, but traffic and other cars I have driven in make me think the speedo is pretty close.

My reason for the post is not to brag on how fast my car is, but to see if there is something to worry about, or if I should be checking the vehicle over for ailen technology.
the only thing unusuall is the overboost disconnected. I looked at the IP and there are scribe marks on the block and the IP, so it probably has had the timing set. but not by me. I know personally the PO and it was a large woman in her 50's so I doubt perfomance enhancing has been done to this car. She is wealthy, and it was serviced regurly by a local indy, so possibly the indy modified the turbo wastegate and alda to give her more gasser like performance. it does not smoke or burn oil. there are drip marks where ever I park the car. when I punch the go pedal for the test, the engine actually roars and everything shakes as it pulls through the first two gears. 60 comes up well before 4th gear. also, several posts say you will not hear the turbo whine while driving the car. my car has a noticable turbo whine on the freeway, but then again, I drive with my windows down... is it normal to be able to hear the turbo whine?
John

pj67coll · #37 06-02-2006, 03:27 PM

Maybe a free flow exhaust has been installed at some time?

- Peter.

vstech · #38 06-02-2006, 03:33 PM

Quote:

Originally Posted by pj67coll

Maybe a free flow exhaust has been installed at some time?

- Peter.

the exaust looks basically stock to me.
and also, everything I have read about a free exaust or straight pipe even, says there will be no noticeable power changes from exaust. POSSIBLY slight turbo spool time reduction.
John

bbeardb · #39 06-02-2006, 03:37 PM

Quote:

Originally Posted by vstech

My reason for the post is not to brag on how fast my car is, but to see if there is something to worry about, or if I should be checking the vehicle over for ailen technology.

You should, I would. You have a kick ass car. Maybe speedo error, but even still, it'll probably be around 12 (I'm guessing.)

Let us know when you find that alien technology, that would be cooler than the sub ten 0-60.

Hatterasguy · #40 06-02-2006, 05:42 PM

Quote:

Originally Posted by tangofox007

Does it make any sense at all that the start of delivery would vary by 39 degrees (24 degrees BTDC - 15 degrees ATDC), depending on the timing method being employed?

I suspect that a compression engine would be a little hard to start with the start of delivery occuring at 15 degrees ATDC!!!

Yep your right, I was tired last night.

I am not saying anyone is lieing or anything like that. All I am saying is lets try to figure out why such a car got extremly abnormal numbers. It would be interesting to find out why.

t walgamuth · #41 06-02-2006, 08:49 PM

Quote:

Originally Posted by pmckechnie

Sixto,
I sometimes feel sorry for these people that can only say "impossible","your lying", "can't be", etc. In how many cases does it happen that if they has said "I don't understand how that can be, could you tell me more?" If they would they may learn something from others that have spent a lifetime learning things. I have been working on cars for about 50 years now, and I believe I have learned at least something. My 500SEL has gotten 28.9 average mileage going from NC to Flordia. This was 99.9% hiway, cruse set at 80 most of the time, with extensive tuning for MPG only. It had a very poor idle, and little low speed power. It ran like gang busters above about 50. 0 to 60 was probably 15 sec which is terrible for a 500SEL. I sense have tuned it back for overall drivablity and it is a joy to drive. Same trip to Fl after seting it back to (Normal) got 22.1 which is still good in my opion.
If people would just listen to others and ask how, they may learn something useful.
When I was 16 my Father was probably the dumbest man I knew. When I was 50 he knew more than i will ever know. When he passed away, he was the smartest man ever. Actually, he was always the smartest man ever and over those many years one thing he taught me was "listen, you may learn something" and he was right as usual.
Now if there is anyone that would like to know how to get 29+ MPG from a 500SEL or probably most any car, let me know and maybe I will give away some of the knowledge I have gained over the years. But if you say "Stop lying" or something to that effect, forget it.

does the sharing involve the exchange of money?

tom w

pmckechnie · #42 06-03-2006, 02:07 PM

Yes, if the person wanting me to share the information is one of the ones that said I was lying, etc. If it is someone who has an open mind and would just like to learn something that may or may not be of any value, then the sharing will be gladly given.
Which side of the fence are you on?

sixto · #43 06-03-2006, 02:18 PM

I wonder if the advantage of cars that do better than spec has to do with shifting. I never timed the SDL but it felt quicker without the engaging the kickdown switch. It revved a couple hundred rpm higher with kickdown but then lingered against the governor wasting precious time.

It doesn't seem like John, MBeige and DslBnz row through the gears manually to achieve their times so maybe it's more the transmission's state of tune than the engine's. Thoughts?

Sixto

DslBnz · #44 06-03-2006, 02:42 PM

Quote:

Originally Posted by sixto

I wonder if the advantage of cars that do better than spec has to do with shifting. I never timed the SDL but it felt quicker without the engaging the kickdown switch. It revved a couple hundred rpm higher with kickdown but then lingered against the governor wasting precious time.

It doesn't seem like John, MBeige and DslBnz row through the gears manually to achieve their times so maybe it's more the transmission's state of tune than the engine's. Thoughts?

Sixto

First off,
My SDL is not stock. I've already stated that.

Cheating acceleration times by altering transmission vacuum pressure to boost performance does NOT count, IMHO. It shouldn't. You most certainly CAN achieve better results by using that method (gaining more power to the wheels for a brief amount of time during gear changes), but at what cost? I'd rather have a transmission that lasted longer than 10K miles, given the fact that, AFAIK, its original. I keep my modulator setting as harsh as possible (to a bearable limit).

WOT, past kickdown is the proper way for maximum performance. A 603 should NEVER bog down before it shifts into a higher gear. That only happens usually when you're running up against the governor (appx 5K + rpm). The power delivery curve should be linear at all times.

Hatterasguy · #45 06-03-2006, 06:37 PM

With a 617 you might gain a bit by short shifting it, they seem to max out power wise right around 4k. Someone needs to run a bunch of zero to 60 times and see what doing that does.

But not so with a 603, rev that sucker as high as possible, they make all their power from 3k-4,800.

You may gain a bit if you adjusted the tranny so it bangs from gear to gear, ie no slip. Like "race" mode in a modern computer controlled tranny. But usualy with an auto the best way to launch is to power brake a bit and just floor it. If you have a lot of power, like an E55 for example, the traction control should launch you.