So as everyone knows, I am running the MS standalone and just replaced my clutch. In my head, I predicted that I might see more boost than previously because the clutch is no longer letting go (it used to let go nearly completely) and thus the motor is loaded more and will make more boost, in theory - I think this true because my only perceptible "clutch slip" was when the revs would go up as if I were in neutral - but surely the clutch slips in a "less dramatic" manner and one would not quite tell. Well - I think this is absolutely the case. I was going through the toll booth onto the PA TPK and I rocketed first and second gear and heard my wastegate (dumping to atmosphere) louder than I have ever heard it before. I wasn't much concerned until it missed under boost (afrs were healthy though!) and I obviously let off.

So I boosted it up high like that several more times, missing consistently as the wastegate went full-open. Took it easy (sorta) the rest of the ride to school and attributed my misfire under boost to fouled plugs. Got home, processed the datalogs and noticed that yes, in fact, my MAP sensor is reading higher than previously - used to read a max of 166 kPA and now reads a max of 171 kPA (or 10.2 psi, 9.5 psi formerly). Interesting, I know. So then it dawned on me, I have over-boost protection enabled - when MS sees > 172 kPA it cuts spark. That would explain my miss and the huge fireballs I was blowing until I let off. What I think is happening is I am getting slightly more creep (8.7 or 9 psi spring in wastegate) than previously because of proper traction in the drivetrain and the car was cutting spark under boost.

Even though the datalog shows 171 kPA and not 172 (the cut point) I bet it cuts right before the desired value - I moved it up to 175 kPA (10.8 psi) and am going to see what happens tomorrow or the next day. But shit, with this new clutch, first and second gear spin very, very easily compared to previously!

Interesting. I wonder if this will fix it. How long until you dyno it? Everyone's waiting you know.:buttrock

your so patient. My anxious ass would be running back out to my car to see if i fixed the problem. So, im gunna go ahead and assume your not running any kind of boost controller besides waistegate spring??

Careful with the manifold and shooting fireballs. I've seen them crack from heat like that.

Interesting. I wonder if this will fix it. How long until you dyno it? Everyone's waiting you know.:buttrock

X2....:buttrock

Careful with the manifold and shooting fireballs. I've seen them crack from heat like that.

Thanks yeah this is not the first fireball episode heh. When I was open downpipe this puppy would light the highway up. Manifold seems to be just fine. I'd rather burn the fuel in the motor than in the pipes haha.

This should fix it - its very wet today and I don't think I can get on it without it being very dangerous (it was hairy last night in the foggy/misty weather). I have to run errands later today, I may get on it in 2nd/3rd gear and see what happens.

I am in no rush to dyno it really, I know you guys are dying to know, I am too, but I don't want to waste money or damage the car - I am going to continue on the street until it feels perfect.

your so patient. My anxious ass would be running back out to my car to see if i fixed the problem. So, im gunna go ahead and assume your not running any kind of boost controller besides waistegate spring??

No controllers - just spring. I don't like the complexity of a controller. Of course when I get the other motor done I will use one, but I'll be going manual controller because I like the ease.

Patience is what keeps the car on the road :)

Fireballs are neat, but need to be lit closer to the exhaust tip, like running a shift activated sparkplug/coil diverter, BOV line entering exhaust near the tip of an overrich ehaust charge, Spitting fireballs when shifting gears :evil2 Muhahaha ! Part of my evil plan to dominate the road.
Grat job on tuning can't wait to what cause such a thing.
MS rocks :buttrock

No controllers - just spring. I don't like the complexity of a controller. Of course when I get the other motor done I will use one, but I'll be going manual controller because I like the ease.

Patience is what keeps the car on the road :)
+1 on the manual....thats the same route im going, 20 bucks and nice easy set up :)

Speaking of getting manifolds hot... my stock ECU would do an ign. cut as a speed limiter(about 120ish mph). On the track everybody said they could see a solid 3 ft flame coming out of the tailpipe when hitting it. Apparently it got things hot, as it turned the stock cast iron manifold, turbine, and half the turbine outlet a weird orange/rust color then it faded into the normal carbon. It wasn't MMT residue, as I had never run any MMT on the car. I think it just got things "really hot" and toasted the carbon off the walls.

Thank goodness for sodium filled exhaust valves eh? heheh

Any knock sensing that could retard timing ? Or very conservative ign values retard rise EGT a lot. Flames are from the ign cut and back on, I guess the injectors keep firing when the limiter hits, then the next ignited burn fire the whole exhaust or it simply burns without spark because of a red hot something in the exhaust.
Gotta love Na valves and/or ceramic coated ones.

turbo boost is very load sensetive. The more load on the engine, the faster and more boost that can be had. Auto tranny cars will generally make boost faster due to the extra load created by the drivetrain. You'll also find on the street or dyno that you'll make more boost in the higher gears than lower gears for the same reason, load.

RussC

Yeah I have always made boost sooner/more in 3/4/5 vs 1/2 and understand that - I suppose my clutch slipping was only providing enough load to make 166 kPA and now that its rock solid its making 171+ kPA.

Shouldn't you be easier on your new clutch? Give it time to break-in before you thrash it.

Shouldn't you be easier on your new clutch? Give it time to break-in before you thrash it.

Been about 200 miles now. I am not thrashing it - for the most part just going WOT. That's fine, what I guess you should be careful of is hard engagement between gears - but for the most part I am nice to it between gears. I think I have about 200 miles on it and it feels great. Spinning 3rd gear a little on these tires this afternoon.

I am in no rush to dyno it really, I know you guys are dying to know, I am too, but I don't want to waste money or damage the car - I am going to continue on the street until it feels perfect.

You really should dyno tune it using their wideband, it's safer for you and the engine. You will end up breaking something or hurting the engine before you hit the dyno trying to tune it for max power, plus it's a bitch driving and trying to tune on the laptop at the same time, i've had a few close calls with tree's and canals @ 100+mph:eyecrazy

You really should dyno tune it using their wideband, it's safer for you and the engine. You will end up breaking something or hurting the engine before you hit the dyno trying to tune it for max power, plus it's a bitch driving and trying to tune on the laptop at the same time, i've had a few close calls with tree's and canals @ 100+mph:eyecrazy

I am not trying to tune it for max power - I am tuning where it runs and feels right - no hesitation or misfires etc. I don't tune the laptop at the same time - I run it rich, I datalog, I come back, pull some fuel, rinse, repeat...:)

Feels like it is pulling great - CerealKilla and another friend just went out with me on the roads to take it for a spin - pulls real real hard. To bad its damp out, traction into 2nd and 3rd is a little awkward.

If you are losing traction in 3rd gear with that heavy of a vehicle when it is dry, you are doing well so far. Keep it up and get that MBC quick!

If you are losing traction in 3rd gear with that heavy of a vehicle when it is dry, you are doing well so far. Keep it up and get that MBC quick!

weight hurts traction. You get proportionally more inertia to accelerate than you do grip from increased normal force.

Spinning tires is also usually more a function of instantaneous torque load than the total value. That and bad tires make spinning easier too. :)

My traction issues went away in my 5 series when I made more power more smoothly. ;)

You really should dyno tune it using their wideband, it's safer for you and the engine. You will end up breaking something or hurting the engine before you hit the dyno trying to tune it for max power, plus it's a bitch driving and trying to tune on the laptop at the same time, i've had a few close calls with tree's and canals @ 100+mph:eyecrazy

Dont worry he really seem to know what he's doing. Besides dyno tune is soo expensive, I will not use it, I rather buy some more goodies with the extra cash. Shure thing dyno tuning is great when you can afford it.

weight hurts traction. You get proportionally more inertia to accelerate than you do grip from increased normal force.

Spinning tires is also usually more a function of instantaneous torque load than the total value. That and bad tires make spinning easier too. :)

My traction issues went away in my 5 series when I made more power more smoothly. ;)
Great point Mike. It is so relevant. I should have asked what tires he is using and the amount of tread. Even more important, without knowing the power curve due to the amount of timing at this rpm point or lack of at that rpm point, I have no idea how hard his turbo comes in at and that is huge. Vader M3(Pablo) and I have discussed this in the past on this board. That is one reason I really liked the GT30R because it hit full boost quick but the actual power delivery was so smooth!

I am on typical all-season 205/65/15's with like 90% tread. They're just continentals, they're for the winter months. The car doesn't struggle much to break free but we've had foggy weather for the last 3 days I want to try driving in total total dry.

Dont worry he really seem to know what he's doing. Besides dyno tune is soo expensive, I will not use it, I rather buy some more goodies with the extra cash. Shure thing dyno tuning is great when you can afford it.
Going to the dyno is either as a fast(er) way to tune, an easier way to hold load at a certain point, or a way to get a pretty graph. An accurate vehicle weight and vehicle drag data combined with a flat road and vehicle speed being measured at a very quick interval can provide a very accurate *dyno* like plot. That is usually enough for tuning purposes and could provide some fairly accurate numbers for the people on this board too.

change in speed over change in time is accleration. and F = M * A. The drag side of things is a little more involved, but still not too difficult. But we'd have torque at the rear wheels at many points, needing only RPM to correlate that to HP... and *pretty* curves.

Hell, I wouldn't be suprised if there was a plugin for MS that takes a log and turns it into plots by now.

Great point Mike. It is so relevant. I should have asked what tires he is using and the amount of tread. Even more important, without knowing the power curve due to the amount of timing at this rpm point or lack of at that rpm point, I have no idea how hard his turbo comes in at and that is huge. Vader M3(Pablo) and I have discussed this in the past on this board. That is one reason I really liked the GT30R because it hit full boost quick but the actual power delivery was so smooth!
I miss having extreme control over the turbo in that regard. Its easier to do it with technology than just a standard ECU and conventional turbo. Takes a lot of data (TIT, TOT, pressure in both locations as well, turbo RPM, engine RPM, wheel speed for each of the rear wheels, vehicle speed, and gear) but the end result is amazing. If you can bring things online in an extremely smooth manner, grip is a lot less of an issue. If you can have the torque curve follow the grip of the tire... :D

Well most BMW's have a front/rear weight ratio of 50/50, if the torque is applied smoothly, a good amount of weight is transfered on the rear wheels (more like 25/75 depending of the powerplant), planting them solid on the pavement, if the torque comes all at once the weight on the drive wheels remain the same and since traction is broken, not much acceleration, so weight transfer happens, etc.. One shure thing the tires quality play a premium role is the equation.

Going to the dyno is either as a fast(er) way to tune, an easier way to hold load at a certain point, or a way to get a pretty graph. An accurate vehicle weight and vehicle drag data combined with a flat road and vehicle speed being measured at a very quick interval can provide a very accurate *dyno* like plot. That is usually enough for tuning purposes and could provide some fairly accurate numbers for the people on this board too.

change in speed over change in time is accleration. and F = M * A. The drag side of things is a little more involved, but still not too difficult. But we'd have torque at the rear wheels at many points, needing only RPM to correlate that to HP... and *pretty* curves.

Hell, I wouldn't be suprised if there was a plugin for MS that takes a log and turns it into plots by now.

Can't say it's wrong. But I definitely ain't there yet. There is no dynos in a 60 miles radius from where I live. I was planning on using megatune and hold the load with the brakes to get it to read and efficiently tune all the RPM/load using a wideband O2 sensor. I think that ultra magaquirt will have a wideband O2 sensor controller, it should be out when I'm done with the block (witch I'm still shopping lol)

Well most BMW's have a front/rear weight ratio of 50/50, if the torque is applied smoothly, a good amount of weight is transfered on the rear wheels (more like 25/75 depending of the powerplant), planting them solid on the pavement, if the torque comes all at once the weight on the drive wheels remain the same and since traction is broken, not much acceleration, so weight transfer happens, etc.. One shure thing the tires quality play a premium role is the equation.

Its more appropriately called load transfer instead of weight transfer, but I'm sure you get the concept. Those numbers sound way off though.

Load transfer is a function of CG height, acceleration, and wheelbase.

so lets say we start with 50/50 weight distribution on a 3500 lb vehicle. Front sees 3500/2=1750, rear sees 1750 as well.

Lets assume a CG height of 18 inches. (which sounds like a reasonable assumption to me for an E34.) The wheel base is about 108 inches.
I don't see his car pulling 1G of acceleration, probably closer to 0.6 or so, but we'll use 1G as an extreme example.

so we have 1G * 18 inches / 108 inches. = 1 x 18/108 = 0.1666
so a ~16.6% shift in load.
16.67% x 1750 = ~291
so the front loses 291 lbs lf load and the rear gains it.

1459 front, 2041 rear
which is ~41.6% front, ~58.3% rear
a far cry from 25/75

Yes I exaggerated a bit with my 25/75 but from my calculations is close to 33/66. The only little mistake you made was that with 108 inches you set the center of gravity over the front wheel. 1 G (damn big turbo lol) 18 inches above would set the COG 18 inches back 72" from the front and 36" from the back. witch set 33 %/66 % weight ratio.
I guess the truth lies somewhere between the two of us ;)

108" is the couple that the torque of the accelerating Cg has to act upon, so looking over techno's calcs I'd say he's right. If it were a huge difference at just 1G of accel, then things like big Top Fuel dragsters would probably run more weight up front so as to not flip over on accel.

Yes I exaggerated a bit with my 25/75 but from my calculations is close to 33/66. The only little mistake you made was that with 108 inches you set the center of gravity over the front wheel. 1 G (damn big turbo lol) 18 inches above would set the COG 18 inches back 72" from the front and 36" from the back. witch set 33 %/66 % weight ratio.
I guess the truth lies somewhere between the two of us ;)

:confused how did I set the CG over the front wheels? Load transfer is always described as:
(aceleration x mass x CG height) / (base distance)
For cornering, this is : (aceleration x mass x CG height) / (track width)
and for acceleration this is : (aceleration x mass x CG height) / (wheelbase)

That gives a load transfer number that can be added or subtracted from the respective end of the car.