mxzxracer16

Hey guys looking for some others readings for comparisons, on my cl65 which has a tune on it on hard pulls from down in the lowend my data logger "dashdaq" I see 37psi it maxs for a split second there and drops to about 35ish then slowly drops on the rest of the pull. Soooo....

-1st questions how much of a range do the MAP sensors have Ive never seen over 37 listed so im thinking thats the end of the range, and also because it feels to me is that once it hits the number "top of its range" that it kicks it into a bit a limp and starts pulling boost back thats why I think im seeing my intial drop as soon as it hits 37.

-2nd So a reading of 37 = 22.7 boost at the intake is anyone else getting this high of a reading?

Any other info from fellow v12tt owners would be greatly appricated. Thanks

radride

I don't know much but I'm pretty sure that at 37 psi those little turbo's, if they even can put out that much, are blowing nothing but hot air.

And to get this straight you are reading the boost pressure at the turbo's or the manifold? Because I am unsure how 37 psi = 22.7 psi at the manifold unless you are implying there is a 15 psi pressure drop across the system which again I am unsure of.

R.K.

Flight Test

I tried to attach an excel file of a datalog run but we are not allowed to attach .xls files. SO.... I made a pdf of just one line at max boost at 17.3 PSI or 221 kilo pascals. This is on a stock 2006 S65.

The boost curve is pretty funny looking on a stock car, it pulls back as the RPM rises. Max boost is around 3K to 4.5K and it starts falling down to about 15PSI at redline. I am guessing that is a product of very tiny turbos, but perhaps it is an engine managment function.

What do the boost curves look like on a tuned car?

I datalog using the Torque APP on a droid phone.

radride

Most stock turbo cars do that. Its all about controlling the wastegate duty cycle but eventually these wastegates on our cars don't have stiff enough springs to overcome the pressure and end up opening anyways.

R.K.

Flight Test

I am guessing that the 37 is the PSIA (Absolute) to find the actual boost you have to subtract the barometric pressure usually 14.7PSI which would make 22.3 PSIG (Gauge) of boost.

I do not have much experience with Dasdaq so that is just a guess. Do you have the units that are attached to the readings?

radride

That makes sense.

R.K.

mxzxracer16

[quote=Flight Test;4781210]I am guessing that the 37 is the PSIA (Absolute) to find the actual boost you have to subtract the barometric pressure usually 14.7PSI which would make 22.3 PSIG (Gauge) of boost.


-Bingo thats exactly why I listed it 37 on dashdaq figures in Stoiciometric "14.7" which = 22.3 in the manifold.

-I hooked up a hand pump on the sensor and 39 is the MAP sensors max on the dashdaq and star, im going to try it on a friends S65 and see if his sensors correlates to mine. But at 22ish under full boost I know I dont want anymore boost on pump fuel and the tune I have.

-Anyways here is the obvious conclusion with the small turbos and wastegate operations as R.K. mentioned bottom line is they need bigger turbos like Speedriven is working on so they can build, hold, and maintain 21-22 psi and these cars will make silly HP and a nice even torque curve. Ive talked with Marcin and cant wait till they have this kit together.

Flightplan ive logger my car stock and tuned the boost log looks pretty much the same just the car tuned boosts higher but the rise and fall across the rpms is almost identical from what Ive seen or at least very close the turbos just can't hang in the higher rpms

saintz

I was thinking the same thing as radride when I first read this. 40 lbs of boost and you're loosing almost half of it through the IC? Do you have a diesel truck motor and a bathtub for an IC?

Makes much more sense now.

That's still a pretty good bit of boost for a stock system. Seems like if the MAP tops out so close to stock boost, that doesn't bode well for tuning. I'm wondering how the aftermarket tunes cope, and if the 65 has a better sensor. Or under WOT does it ignore the MAP and use some other calculation? (Assuming that it is in fact topping out)

2003 S600

Anyone log timing under boost. I am dipping into +1-+3. That is ATDC. Something is pulling timing like crazy. Also some detonation between 15-20 psi boost. Spark plugs? Injectors? What do you think? I peaked at 37 psi absolute which is 22.3 psi boost also.

mxzxracer16

Ill check my timming on the logger tommorow and see if Im getting comparable readings. Also I see you say your car hits 37 on the logger does it only touch it for a second then stedily drop off?

mxzxracer16

As far as the detonation I always feel that with these 275's its the heat coming in the form of boost that causes the detonation.

saintz

Check your IC pump.