Picking a New Full Race Stall Speed

[BadAssGN]

Cal, have you ever tuned without using a dyno?

Cal has Tuned a car from the other side of the country while sitting on a toilet
in a hotel room :biggrin:


Is there any particular reason you don't feel some of these guys are credible enough to listen to?

is it more gratifying to work all this out on your own?

 

[Alky V6]

Cal has Tuned a car from the other side of the country while sitting on a toilet
in a hotel room :biggrin:


Is there any particular reason you don't feel some of these guys are credible enough to listen to?

is it more gratifying to work all this out on your own?

It's not that I don't feel they're credible. It's just that if I ask for advice, and get it, then I will process it and decide whether or not I will use it. I'm smart enough myself to decide whether I can use the advice or not, and when I might use it, if I do.

On the other hand, if someone is trying to jam advice down my throat in an insulting and demeaning manner, especially if I didn't ask for it, then I certainly will be majorly turned off to that sort of person, and would rather figure things out for myself, which I'm more than capable of doing.

When I was playing with the T76 combination, if I had listened to the experts about the TC before I had finished my plan to maximize the tune on the engine first, I would have ended up needlessly replacing a TC that would have ended up working just fine.
How could they be experts on an engine combination that they had never dealt with before? When they started giving advice for a TC on an engine combination no one has ever dealt with before, and before it was even tuned in yet, that was a major red flag to me that they were a little too anxious with their advice, to put it politely.

But you're right, too. I do find it more rewarding when I go through the learning process myself and come up with the answer on my own. And those that manage to politely contribute help along the journey are greatly appreciated and graciously thanked.

 

[HighPSI]

Cal has Tuned a car from the other side of the country while sitting on a toilet
in a hotel room :biggrin:

LOL!! There is quite a bit of truth to that :redface:

I misunderstood the purpose of these threads. If this is more of an "info-mercial" and you aren't really wanting any help then I will kindly step aside.

 

[johnplogii]

Cal has Tuned a car from the other side of the country while sitting on a toilet
in a hotel room :biggrin:

Now that's funny!

Don, I know you made the converter work with the old t76 & it worked pretty well, but are you convinced that it would not have done any better with another converter? Most people are probably looking at the nitrous as a band-aid, which it is if you are not spraying it while going down the track. The old combo could possibly have been made to work properly without any nitrous, with the right converter. I take it you just like being different & WANT to use the nitrous?

 

[Dusty Bradford]

2 hours of dyno time is comparable to a full track day for me. I understand the difference in fuel regarding the tuning aspect, as I am undergoing the same process. I agree with your TC tuning concept but common sense and 2nd hand experience usually wins. I went to Dusty for a convertor for my new combo and without making a single run I'm betting it's too loose. Since my motor is based around a high velocity/low rpm exhaust design it currently flashes to 5000rpm in 3/10's of a second with zero boost. I'm hoping it has good coupling characteristics at a higher rpm(7500max)bute'll see. In the mean time I will test and determine what's needed but at least I'll have a good baseline and send the PTC convertor back for the free re-stall if needed.
BTW, at 2850 my 76gtq maxed out at 780rwhp. After installing the 47/88 I only picked 2/10's in the 1/8mi but the fuel map only changed in the 3500 -5000rpm area.

This is the V8? If it's flashing to 5000 rpm without nitrous and your not seeing any boost it does sound too loose. But it sounds awkwardly loose like there is a fluid issue.

Are you using any sort of variable stall? To be that loose it sounds like the converter is either not getting enough fluid or is blowing it out to easily?

I'm trying to remember if your using a powerglide. If so, are you running a ringless input shaft?

 

[Dusty Bradford]

.

When I was playing with the T76 combination, if I had listened to the experts about the TC before I had finished my plan to maximize the tune on the engine first, I would have ended up needlessly replacing a TC that would have ended up working just fine.

Don, I don't remember much about the T76 deal but I have a question. When you say "maximize the engine tune" are you talking about the timing and a/f ratio's during spool-up? Or did you just keep spraying it with more nitrous until it worked?

If a converter goes from way too tight to "working just fine" the tune would have had to be really far off in left field initially. I can't see you missing the tune that far. To me maximizing the tune deals with getting the right timing and fuel requirements in the engine to deliver the most torque which will increase the stall rpm as much as possible.

 

[Chevota]

This is the V8? If it's flashing to 5000 rpm without nitrous and your not seeing any boost it does sound too loose. But it sounds awkwardly loose like there is a fluid issue.

Are you using any sort of variable stall? To be that loose it sounds like the converter is either not getting enough fluid or is blowing it out to easily?

I'm trying to remember if your using a powerglide. If so, are you running a ringless input shaft?

523ci V8. I didn't get a v6 convertor did I?? Fluid is full. No variable stall. Yes, powerglide with a ringless input shaft. NO nitrous.

 

[Dusty Bradford]

523ci V8. I didn't get a v6 convertor did I?? Fluid is full. No variable stall. Yes, powerglide with a ringless input shaft. NO nitrous.

Does your transmission have the bushing in the stator support tube around the input shaft? If not, you need it. That is what keeps the fluid from blowing out of the converter under load when running some of the ringless shafts.

 

[Alky V6]

Now that's funny!

Don, I know you made the converter work with the old t76 & it worked pretty well, but are you convinced that it would not have done any better with another converter? Most people are probably looking at the nitrous as a band-aid, which it is if you are not spraying it while going down the track. The old combo could possibly have been made to work properly without any nitrous, with the right converter. I take it you just like being different & WANT to use the nitrous?

BINGO!!! Hand this man a prize! Finally. A sign that someone is actually reading my posts.

As I've explained throughout this thread and throughout this site in other threads, NITROUS OXIDE INJECTION was always part of the plan for this project from the very beginning.

In fact, the first two criteria that was decided on at the very start of this project was that I would be burning methanol and using nitrous/methanol to help spool up a turbo.

THOSE WERE THE VERY FIRST ITEMS ON THE LIST OF SPECIFICATIONS FOR THIS PROJECT!

Please people, burn this post into your heads and maybe,... JUST MAYBE then you might start to understand the whole purpose of this project.

When did I start posting here on this project? The late 1990s? And finally, someone is just starting to understand. Try to imagine my extreme frustration having to put up with everyone's criticizms of what I was doing all these years.

The famous criticizm: If you just use the right TC, you might not need the nitrous at all.

Good Grief. How many times has that been posted. You guys just don't get it. Nitrous and methanol is the foundation of this project. Get over it. I'm not trying to get rid of the nitrous. I'm searching for a combination where nitrous is an important part of the combination.

 

[Alky V6]

Don, I don't remember much about the T76 deal but I have a question. When you say "maximize the engine tune" are you talking about the timing and a/f ratio's during spool-up? Or did you just keep spraying it with more nitrous until it worked?

If a converter goes from way too tight to "working just fine" the tune would have had to be really far off in left field initially. I can't see you missing the tune that far. To me maximizing the tune deals with getting the right timing and fuel requirements in the engine to deliver the most torque which will increase the stall rpm as much as possible.

With the T76 combination, the tuning issues that I was dealing with that finally came into focus on Sunday of the 2007 WCN, was the timing of the nitrous injection, how long to have it on before the release of the transbrake and how long to keep it on, and the timing of the introduction of the aux fueling system. The nitrous shot size that I had happened to choose at the beginning of tuning that configuration happened to be the right shot size for that particular T76/TC combination. That shot size was worked out in a sim.
With the new turbo, the sim showed that the combination would really like a 400hp shot. Interesting, because presently the shot size is up to a 364 and I'm preparing to step up to a 393hp shot. The higher stall TC became necessary because the shot size was getting too large for a 3900 rpm stall speed. Too much charge collecting in the cylinder for that engine speed. That's another story.

The part that was the most tricky was the rpm/map range where the nitrous was turning off and the aux fueling system was turning on. Timing that so that the two systems didn't disrupt each other was the final key to making it all work.

I was dealing with tuning issues that no one on this site could have helped me with. Not even Cal.

After that was straightened out, I was finally able to get a clean pass that allowed me to properly assess the TC that I was using.

Dusty. Can you please do me a favor and educate these people as to the advantages of using nitrous to help spool a relatively large turbo, and how that would affect the choice of the converter, and how efficient the choice might be over me eliminating the nitrous and going with a looser TC to make up for the loss of the nitrous. All with using the same relatively large turbo and the other engine specification choices I've made with this engine.
It's becoming obvious to me that some of these people either don't trust anything I say, think I'm a complete nut, or they're incapable of understanding the tuning and configuration concept that involves nitrous oxide injection to help spool a turbo. And, I'm using the word tuning in the previous sentence to encompass the whole powertrain, not just timing and a/f ratios.

 

[Dusty Bradford]

With the T76 combination, the tuning issues that I was dealing with that finally came into focus on Sunday of the 2007 WCN, was the timing of the nitrous injection, how long to have it on before the release of the transbrake and how long to keep it on, and the timing of the introduction of the aux fueling system.

The part that was the most tricky was the rpm/map range where the nitrous was turning off and the aux fueling system was turning on. Timing that so that the two systems didn't disrupt each other was the final key to making it all work.

After that was straightened out, I was finally able to get a clean pass that allowed me to properly assess the TC that I was using.

Dusty. Can you please do me a favor and educate these people as to the advantages of using nitrous to help spool a relatively large turbo, and how that would affect the choice of the converter, and how efficient the choice might be over me eliminating the nitrous and going with a looser TC to make up for the loss of the nitrous. All with using the same relatively large turbo and the other engine specification choices I've made with this engine.

You have alot going on before ever launching the car. No doubt a converter which was looser down low would have helped you get a handle on the tune quicker. You do have a tuning headache so it's obvious why it takes days of trying different things to get it working properly. When you throw in the extra fuel system needed for methanol it does become difficult to time everything just right to get a smooth transition. Where as a normal combination would take 2-3 transbrake pulls to get dialed in, yours takes days.

So when your talking about maximizing your engine tune, your talking about getting everything timed right to get a smooth transition. When we talk about maximizing an engine tune it's about getting the proper a/f ratio and timing map to generate the highest stall possible to lower spool time. It's much easier for us "cookie cutter" guys because we have less to deal with. I can usually tell if a converter is too tight by the 1st attempt to get on the 2 step. I have tested a couple where I made 2-3 attempts to get on the 2 step and then pulled the converter out right away.

 

[Alky V6]

You have alot going on before ever launching the car. No doubt a converter which was looser down low would have helped you get a handle on the tune quicker. You do have a tuning headache so it's obvious why it takes days of trying different things to get it working properly. When you throw in the extra fuel system needed for methanol it does become difficult to time everything just right to get a smooth transition. Where as a normal combination would take 2-3 transbrake pulls to get dialed in, yours takes days.

So when your talking about maximizing your engine tune, your talking about getting everything timed right to get a smooth transition. When we talk about maximizing an engine tune it's about getting the proper a/f ratio and timing map to generate the highest stall possible to lower spool time. It's much easier for us "cookie cutter" guys because we have less to deal with. I can usually tell if a converter is too tight by the 1st attempt to get on the 2 step. I have tested a couple where I made 2-3 attempts to get on the 2 step and then pulled the converter out right away.

See, here's the problem I have with everyone. Early on in the T76 tuning, I recognized where the stall speed was with the TC. Yes, it was very low for the needs of a T76,... WITHOUT NITROUS. But, I was still able to envision the potential for that TC with that combination even before I had finished the tuning and activation timing of all the systems I was dealing with. I was not so quick to pull the trigger on that TC. I had no test results that showed me what the engine was even capable of doing up to that point. As I've harped about earlier in this thread, if the engine performance is a known concrete variable, it is much easier to judge the TC choice from a simple stall test. If you are dealing with a totally new type of engine and systems combination, how can you possibly hope to know what TC will finally be needed? Easy answer, YOU CAN'T POSSIBLY KNOW! Not until the complete engine performance is a known variable.
Dusty. If you had been with me where the tune of my T76 setup was at a point that allowed me to stall the TC, but the rest of the performace of the engine was unclear, what would you have thought about that TC choice? Would you have pulled the trigger on it right there and then? Even before the rest of the performance of the engine was still unknown?
Imagine being able to see the potential of a combination and having people hound on you that the TC choice was all wrong.

 

[it's just a six]

In general,I thought certain turbochargers need a certain amount of stall no matter how a engine runs,good,great, or bad,it still needs a minimal ammount of stall.

Trim wheel size,engine size,A/R on the turbine housing,all have to be taken into consideration,& will need a certain stall for a given spec on a turbo.

Wonder if that makes sense?

 

[Dusty Bradford]

Dusty. Can you please do me a favor and educate these people as to the advantages of using nitrous to help spool a relatively large turbo, and how that would affect the choice of the converter, and how efficient the choice might be over me eliminating the nitrous and going with a looser TC to make up for the loss of the nitrous. All with using the same relatively large turbo and the other engine specification choices I've made with this engine.
It's becoming obvious to me that some of these people either don't trust anything I say, think I'm a complete nut, or they're incapable of understanding the tuning and configuration concept that involves nitrous oxide injection to help spool a turbo. And, I'm using the word tuning in the previous sentence to encompass the whole powertrain, not just timing and a/f ratios.

To put it simply, building a converter for a car with nitrous assist is much easier. You don't have to focus on balancing spooling vs efficieny but just focus in on efficiency and rpm drop.

I do feel I could have put something together for the T76 combo that would performed just as well without nitrous. With the new combo, it's impossible.

To get more in depth, you have to look at ci, power output and shift rpm. For a car such as yours with a 7500 rpm shift point I think a really loose 9.5 based on our TSO style converter would be best. They lock up really well at lower rpms and and are as loose down low as you can find. When looking at another small motor, large turbo set-up with a high shift rpm I would choose something different. Take Titan's drag radial Supra for instance, they are shifting at 8500+ so I would use a 10" core based on a nitrous converter. The 10" core tends to be tighter down low but the nitrous makes up for that, the other tendency of the 10" converter is less rpm drop at the gear change. This would keep the small motor more into it's power range.

 

[Alky V6]

You're right Dusty. Dealing with a high stall TC makes building a fuel map much, much easier. Less area in the fuel map will be passed over by the operating range of the engine. If the hope is to make the fuel table tuning as quick and simple as possible, then the higher the stall the better. As stall speed is increased, less of the fuel map will ultimately need focused attention. This makes the job of the person building the fuel map sooo much easier. Of course, you don't want to go higher with the stall speed than the combination calls for. That just introduces more slippage and waste of energy.

Now, let's pretend for a moment that you're paying attention to what "I" am trying to accomplish. I want to build as complete of a dialed in fuel map as possible. That takes priority to adjusting the stall. Not that adjusting the stall might become the focus later on down the road, but with the fuel table still being worked on, the priority is to build as complete of a fuel table as possible for open loop operation and for simple research into the affects on the fuel table by an uncommonly large turbo cam and intake and exhaust manifold tuning. Remember, this is a learning and research project.

So, with that primary goal in mind, and having just changed the turbo to a larger turbo, would you suggest taking the opportunity to adjust and study the fuel map with the new turbo and keeping the old TC until the fuel map is dialed, maybe providing more insight into the combination, and then, having a more concrete idea of how changing the TC stall has affected the past work on a dialed in fuel map? Treat this as a college experiment. You're studying the affects of different changes to the engine configuration on a dialed in fuel map.

Remember what I said about basic troubleshooting and tuning procedures 101? One change at a time? I wanted to thoroughly study the affects of one change to the engine configuration, before I decided on the next change, or task.

 

[Dusty Bradford]

Dusty. If you had been with me where the tune of my T76 setup was at a point that allowed me to stall the TC, but the rest of the performace of the engine was unclear, what would you have thought about that TC choice? Would you have pulled the trigger on it right there and then? Even before the rest of the performance of the engine was still unknown?
Imagine being able to see the potential of a combination and having people hound on you that the TC choice was all wrong.

I'd would have liked to know the spec's of your current converter to work from. If you could have provided me with the core size, stator design and pump fin angle info I could have told you if it would be close to working or if something entirely different is needed. I'd have an idea of what would be needed to get a 224ci to spool a T76 and shift at 7500 rpm. To get an idea of what an engine is capable of I have to ask what the goals are and depend on an honest answer. If you would have told me 9.0's I would use that info to determine what the engine is capable of and use experience to determine if the bottom stall is adequate for a 76mm. Sometimes I know owner's expectations are a little high:biggrin: but this is how I anticipate how much efficiency is needed to get the job done.

 

[Alky V6]

To put it simply, building a converter for a car with nitrous assist is much easier. You don't have to focus on balancing spooling vs efficieny but just focus in on efficiency and rpm drop.

I do feel I could have put something together for the T76 combo that would performed just as well without nitrous. With the new combo, it's impossible.

To get more in depth, you have to look at ci, power output and shift rpm. For a car such as yours with a 7500 rpm shift point I think a really loose 9.5 based on our TSO style converter would be best. They lock up really well at lower rpms and and are as loose down low as you can find. When looking at another small motor, large turbo set-up with a high shift rpm I would choose something different. Take Titan's drag radial Supra for instance, they are shifting at 8500+ so I would use a 10" core based on a nitrous converter. The 10" core tends to be tighter down low but the nitrous makes up for that, the other tendency of the 10" converter is less rpm drop at the gear change. This would keep the small motor more into it's power range.

So you're saying that if you had seen the initial stall tests with the T76 combination, and knowing nitrous was involved, and not knowing what the rest of the engine performance was going to be, you don't know what you would have thought. It's OK. Who could have known with such a different combination.

 

[Alky V6]

In general,I thought certain turbochargers need a certain amount of stall no matter how a engine runs,good,great, or bad,it still needs a minimal ammount of stall.

Trim wheel size,engine size,A/R on the turbine housing,all have to be taken into consideration,& will need a certain stall for a given spec on a turbo.

Wonder if that makes sense?

Dusty. Would you like to answer this one where nitrous is involved?

 

[it's just a six]

Dusty. Would you like to answer this one where nitrous is involved?

I know you need less stall when nitrous is involved.

Never mind.

 

[Alky V6]

I'd would have liked to know the spec's of your current converter to work from. If you could have provided me with the core size, stator design and pump fin angle info I could have told you if it would be close to working or if something entirely different is needed. I'd have an idea of what would be needed to get a 224ci to spool a T76 and shift at 7500 rpm. To get an idea of what an engine is capable of I have to ask what the goals are and depend on an honest answer. If you would have told me 9.0's I would use that info to determine what the engine is capable of and use experience to determine if the bottom stall is adequate for a 76mm. Sometimes I know owner's expectations are a little high:biggrin: but this is how I anticipate how much efficiency is needed to get the job done.

But what if the final performance of the engine is unclear? This is a combination that no one has ever dealt with. What would you think then? Would you really start changing around TCs where the tune was only to the point of achieving a clean stall test?