[PGA2B]

Ok, guys. I have been searching and I have developed a theory on what "The Wall" we are seeing could be.

Our MAP Sensors top out at 200kpa. So roughly 15psi of boost since you have to subtract 1bar. They are part number# 12580698. Here is a data sheet on it http://www.powerandsignal.com/docs/Products/09350899.pdf.

So my theory is that "The Wall" we are seeing is because the guys running higher boost have maxed out the MAP sensor and thus not getting the full potential of the extra boost because the ECM can't handle the algorithms because they have fallen off the MAP table. So it is only calculating off the max values of the tables instead of taking into consideration the higher MAP kPa values and calculating off those. Thus not reaching full potential. Could this also be part of the heat issues?

Thoughts??

 

[TimmyC]

Most of the fueling and spark is handled through the MAF table so I don't think a maxed MAP is causing any issues.

The air getting hot is the wall. Ryan posted that his IAT2s were over 250 degrees without meth and 170 with! That is the problem and it is not going away.

E85 would make a big difference I bet.

 

[1madstsv]

Do note that the 250 was when my pump was not working. Most runs ended in the 160-175 range but still to hot for it being 35 out and IAT were 37-45. For me it was the heat it cooled off and power went up. New FMHE and big coolant tank first. then try the 8gpm pump. Then re dyno and go to the track and brake. That's how I see it going. Ryan

 

[Guest]

went to summit, now have 8 gpm intercooler pump, new heat exchanger, new front mount intercooler, and bigger intercooler reservoir.

hope to install next week.

 

[1madstsv]

550hp stsv you do know that any thing in the front of the car is just a heat exchanger right. The intercooler on are cars is bilt in to the supercharger. So you are just dubbling up on different types of the same thing. But glade to see every one is trying different things. I'm going to stay with the stock 5.5 gpm bosh pump for now after days and sleepless nights of research. I think any up grades are better than stock. I found a used 04 cobra heat exchanger to play with and the eBay one that just came in the eBay one is a lot biger. I think my eBay h/e and a one gal holding tank will be as good as it gets for my car. I have been on cobra forms and ford gt forms and on ls1tech /zr1 and most run the biggest h/e they can fit and a big coolant tank. So that's what I'm going to try. Ryan

 

[PGA2B]

Most of the fueling and spark is handled through the MAF table so I don't think a maxed MAP is causing any issues.

I got an interesting response from the HP Tuner forum:

you have no fuel control over 15 psi with that map sensor.

Here is what I posted to get responses:

Lets say that your MAP can handle 15psi but you are actually running 18psi. What would the ramifications be? Could that limit power output?


In reading everything I could find including re-reading Greg Banish's book on tuning and I was seeing that several calculations are based on the MAP reading for forced induction cars including fueling. The response I got from the HP Tuner forum supports my findings. Doesn't make it gospel but sure tends to support my theory. I am hoping to get more responses today as I posted that thread late last night. I am waiting for the big guns that tune for a living to chime in over there.

So if the MAP is wrong or maxed out the rest of the calculations based on that faulty reading are wrong also....... I also found that with key on and engine off your MAP reading should be 100kPa which is atmosphere or 0psi. My reading is 98kPa and my boost gauge is reading -.30. I am in the process of recalibrating my MAP sensor. It appears that GM put "Blanket" values in the table which I can understand because they can not test every car coming off the line and that is SOP for ECM programming. Thus why tuning makes a difference.

Now to clear any confusion, this does not effect anyone who is not overboosting...... The factory values for the MAP sensor are close enough not to make a big difference.

Since I will be overboosting this is why I am going down this road.

 

[Guest]

550hp stsv you do know that any thing in the front of the car is just a heat exchanger right. The intercooler on are cars is bilt in to the supercharger. So you are just dubbling up on different types of the same thing.

Right I understand. But can I not go from heat exchanger to additional reservoir to front mount intercooler? Im trying to get as much fluid and cooling as I can, since the IAT2s are so high. Im also looking into a super chiller. Let me know.

 

[PGA2B]

A quote direct from Greg Banish himself.....

Yes, if you are planning to regularly exceed the measured range of the sensor it's time to pick a new sensor that doesn't get maxed out. Otherwise, the PCM will calculate airflow as if you're only at the lower boost reading. This can lead to a lean fuel delivery, underestimated torque number for transmission control, over-aggressive spark, and a few other quirks.

That's good enough for me.

So Coach, Giz, Ryan, Tim and anyone else looking to Overboost- Time to find at least a 2.5 bar or 3 bar MAP Sensor that will fit.

A 2.5 bar will be good to 22.5psi.

For anyone who does not know who Greg Banish is please Google him. It is WELL worth the time.

 

[coach123]

So my theory is that "The Wall" we are seeing is because the guys running higher boost have maxed out the MAP sensor and thus not getting the full potential of the extra boost because the ECM can't handle the algorithms because they have fallen off the MAP table. So it is only calculating off the max values of the tables instead of taking into consideration the higher MAP kPa values and calculating off those. Thus not reaching full potential. Could this also be part of the heat issues?

Great theory.. Please continue researching this more. I started to look into this very same thing when I was getting my car tuned after the upgrades. I think there are a few items besides high IAT2's that are preventing us from getting the power we should be getting (for those that are overboosted). I begin this same search after reading Cobalt SS forums as well as some old HPtuners forums. I have to be honest and say that I don't know enough about tuning cars to dive into this realm so I only assumed that when my car was tuned this issue didn't come up. I have always questioned whether the MAP sensor was affecting something since several Cobalt SS owners had to switch sensors after overboosting. Keep up the good work and let us know if you find something definitive.

 

[TimmyC]

The AFR would go lean on the dyno if the MAP was screwing things up. The proper MAP sensor should be used but it is not the cause of any problems. Above 4000 rpm all of the fueling is based off the MAF sensor. Spark is based off airmass and rpm. Again, not affected by the MAP sensor.

Research into why we're not making more power is good. This is a dead end.

I'd like to see some pulls on E85 or E98.

 

[PGA2B]

The AFR would go lean on the dyno if the MAP was screwing things up. The proper MAP sensor should be used but it is not the cause of any problems. Above 4000 rpm all of the fueling is based off the MAF sensor. Spark is based off airmass and rpm. Again, not affected by the MAP sensor.

Research into why we're not making more power is good. This is a dead end.

So you are claiming to know more than Greg Banish? Let me refresh your memory:


Greg Banish is a mechanical engineer and motorsports enthusiast who works as an OEM calibrator by day and professional engine tuner in his spare time. After studying for a bachelor’s degree in Mechanical Engineering at GMI Engineering & Management Institute (Kettering University), he wrote his thesis on vehicle instrumentation and measurement.

Putting this education to practical use, he founded his own performance shop outside of Detroit and has served local enthusiasts, shops, automotive companies and OEMs. Greg spent three years working for General Motors as the hybrid powertrain calibration engineer responsible for the Chevrolet Volt fuel economy and emissions. Now he works for Power-Tec Engineering as the senior engineer for supercharger systems.

This is the guy who did the calibration for fuel economy and emmissions for the Chevy Volt, Teaches a Tuning class, and has published books on tuning???? REALLY????? What are YOUR credentials and how many tuning books have YOU written.

Please:thehand:

 

[TimmyC]

Maybe you should ask him for tuning tips instead of me then.

 

[PGA2B]

Maybe you should ask him for tuning tips instead of me then.

I have. How do you think I got a response from him?

If you look at the tuning interactions you and I have had I suggested things to you that I was trying and asked for your opinion and bounched ideas off you. If that is asking for tips then I guess I am juilty. I have also sought out professioinal tuners on the HP Tuners forum for guidance and advice. That is the mark of someone who wants to learn. I have never claimed to be an expert and I am far from it. Since you have an STS-V I include you in what I try. We are in unchartered territory here so if we don't exchange ideas, what we are doing, and what is working then nobody benefits. I thought this was what the forum is all about? If you don't want me to share with you what I am doing then just say so.

If that is the best you can come up with then go play with your turbo.......

 

[TimmyC]

I'm getting tired of being belittled by you on the forum here. I've provided correct info about the MAP sensor and its effect on the car but all I get in response is a sarcastic reply. None of the stuff Greg said could happen is happening. That doesn't mean he is wrong or I am smarter than him, it just means that the info does not apply in this case. We can measure both the fuel and the spark. Those are the only things the computer has control over that affect max power. Going lean? No. Over aggressive spark? No. Neither is the problem. The things he referenced are driveability issues, not max power issues.

I am going to go play with my turbo right now because I have found "The Wall" and its name is "Crappy Supercharger."

 

[PGA2B]

I'm getting tired of being belittled by you on the forum here.

Really?? That is truly the pot calling the kettle black. You come into every thread I start and nearly every post I make and tell me I'm wrong, it can't work like that, the air getting hot is the wall. This is a dead end or some other comment and you say I belittle you?

Your posts come off like you are a god and know everything, and everyone else is wrong and not even open to other opinions and views. I'm not the only member that feels this way.

This thread we a THEORY. You posted your opinion and belief and I gave information from an Industry expert and you basically said he was wrong too and you know how it works. Have you checked your MAP against atmosphere? If so what is your MAP reading at key on engine off? I posted my reading and it was NOT calibrated correct. If that sensor is not correct then every other reading based on it is also incorrect. Plain and simple. If you max out that sensor then you are going to have issues with other tables because you've went off the grid..... I was just saying that this may be part of the issue.

You need to do a reality check Tim.

 

[1madstsv]

I talked to my tuner to day abought this he said my map is 250kpa so it is a 2.5 bar. Also I talked to the Company I got my meth kit from and they said that the way I have it to come on it would half to be at least a 2.5 bar or 3 to work. I could not remember so I called to get experts say on it. My tuner and the owner of the meth company both think it was the heat that was my number one hold up. So in a few week I will re dyno and try some new tricks and hope for greatness. Ryan

 

[TimmyC]

Really?? That is truly the pot calling the kettle black. You come into every thread I start and nearly every post I make and tell me I'm wrong, it can't work like that, the air getting hot is the wall. This is a dead end or some other comment and you say I belittle you?

Your posts come off like you are a god and know everything, and everyone else is wrong and not even open to other opinions and views. I'm not the only member that feels this way.

This thread we a THEORY. You posted your opinion and belief and I gave information from an Industry expert and you basically said he was wrong too and you know how it works. Have you checked your MAP against atmosphere? If so what is your MAP reading at key on engine off? I posted my reading and it was NOT calibrated correct. If that sensor is not correct then every other reading based on it is also incorrect. Plain and simple. If you max out that sensor then you are going to have issues with other tables because you've went off the grid..... I was just saying that this may be part of the issue.

You need to do a reality check Tim.

I do come off like a dick on the internet. I'm not like that in real life. It may seem like I'm singling you out but there are not many people on here discussing things. I will try to be more tactful.

My statements about the MAP issue stand however. I do not think you'll find them to be untrue.

Here's my thinking on the problem people are having at the 440-450 range: We can see fueling through a wideband gauge; we can see timing on logs; and we can see air temp on logs. Air temps are increasing rapidly with any departure from stock boost levels. I believe this is the problem people are having. Poor intake manifold integration into the blower case and a marginal intercooler add to it. The air is getting hotter and the convoluted intake tract is compounding the problem. Any overdrive, either a pulley or the Snakebite conversion, increases the load on the crank as well. Two of the three people here with Snakebite conversions have had their balancer bolts back out. Our balancers are not keyed to the crank and the extra drag from the overdrive is causing them to slip and the bolts to back out. I think people don't want to hear that the blower is the problem because it is the most expensive thing that could be a restriction. This is my theory. In my mind, it is the only thing that makes sense. If anyone proposes a different idea that makes more sense, I'll be the first one to jump on board.

 

[The Raven]

I'm going to have to agree that the hot air problem is probably what we should address first. A good friend of mine has an 03 Cobra and is experiencing the exact same problems that we are. His dyno graph looks exactly like TimmyC's. Boost is consistent, AFR is in the proper range for the entire run, but despite gains all the way up to 4000rpm, torque and resulting HP gains go flat above 4000rpm. He said he hit 460rwhp with just a pulley, intake, and exhaust. Since then he has gone even bigger with several more mods (including another step in pulley size), and has gained a mere 7lbft's, and actually lost HP. Clearly heat is his problem also. The only caveat is that he never logged air temps so I can't really say where he's at and compare it to our hot blowers. We're going to work on that.

When I get to this project this summer on my car, unless you guys have made some breakthroughs, i'm going to do an intake and pulley, tune and dyno (and log air temps of course), then try cooling upgrades one at a time. This seems to me like our most cost effective option.

Though i'm not targeting 500whp+. If I can get to 440-450whp, i'm very happy. Regardless, if we don't have better data by that time, i'll at least be able to provide proof on the effects of expanded charge cooling.

 

[PGA2B]

I talked to my tuner to day abought this he said my map is 250kpa so it is a 2.5 bar. Ryan

Are they sure because this thread says it is a 2 bar and confirmed by Delphi and all the informaiton I could find shows it is a 2 bar. There seems to be quite a lot of confusion about it. If it is a 2.5 bar then I am completely off the mark and unless we get over 22psi then the factory is good. But as I said the info I found showed we have a 2 bar and only good to 15psi which you overboosted guys are exceeding. It will be interesting to see how the heat reduction mods do for you. It will also be interesting to see if heat is the only hurdle we have.

Here is the thread.

http://www.ls1tech.com/forums/force...phi-confirms-cobalt-sensor-12580698-2bar.html

 

[TimmyC]

It looks like Jamie is right about the MAP being 2 bar. Engine Diagnostics-Airflow shows that the stock MAP sensor is 200kpa. Upgrading to a 2.5 or 3 bar MAP looks easy if someone wants to try it.