The Only 3300 lb. Buick V6 in the 8s using...

[Alky V6]

Fryguy. Have you ever used nitrous to spool a turbo? It's all right if the answer is no. A lot of guys don't use nitrous.

 

[Fryguy]

Fryguy. Have you ever used nitrous to spool a turbo? It's all right if the answer is no. A lot of guys don't use nitrous.

The answer is no. I have not. I think nitrous is really cool, but I'm really not that smart of a guy, and my race car is complicated enough as it is. I can barely remember to turn the boost controller on, so I prefer to choose a turbocharger/engine/converter combination that will work properly for the speed I want to run.

 

[turbobitt]

These turbo discussions remind me a lot of camshaft discussions, as we all try to tailor the correct map for a specific application. But then variable valve timing was introduced, and then perfected, changing how we look at camshaft specifications entirely. The same can be said with turbo chargers of course, but has anyone here actually played with a variable turbine geometry turbo like a Holset found on a diesel...?

I done a lot of dyno work with the Holeset VGT. All on diesel stuff. And iteresting this to note that the Engineer I was working with said that there was a 60 HP difference between a low and high effieciency turbo.

Also, at the time I was working with them, they were using titanium compressors. This was not for a flow advantage like most would think. The gains with titanium were due to the fact that they can run this in overspeed conditions without overstressing the compressor.

There are other things to consider with VGT's. They were at the time a popular solution for emissions. This was because they cold control backpressure to some degree and promote EGR flow.

Allan G.

 

[Alky V6]

Fryguy.
edit: You answered it. Good.
Next question.
Given the option of two single turbos and absolutely no concern with how you were going to have to get it spooled up, which would you pick? One that gave you 76% eff. throughout the run, or 65% eff. throughout the run?

 

[Fryguy]

Fryguy.
edit: You answered it. Good.
Next question.
Given the option of two single turbos and absolutely no concern with how you were going to have to get it spooled up, which would you pick? One that gave you 76% eff. throughout the run, or 65% eff. throughout the run?

That's not really how I build cars. I always pick the number I want to run first, then figure out how much power/rpm I will need to run that number. Then I pick the turbo/engine that will make the necessary power/rpm.

I normally build some amount of "scale-ability" into the combination so that I can step up if necessary, but I've been playing with cars for many years and doing it this way seems to make the most sense for me.

 

[Alky V6]

That's not really how I build cars. I always pick the number I want to run first, then figure out how much power/rpm I will need to run that number. Then I pick the turbo/engine that will make the necessary power/rpm.

I normally build some amount of "scale-ability" into the combination so that I can step up if necessary, but I've been playing with cars for many years and doing it this way seems to make the most sense for me.

Just pretend for the moment that every other factor had been worked out and the only decision you had left in front of you was the two efficiencies. Which one would you pick. Absolutely no concern with how you were going to have to spool it up. Simple question.

 

[turbobitt]

Fryguy.
edit: You answered it. Good.
Next question.
Given the option of two single turbos and absolutely no concern with how you were going to have to get it spooled up, which would you pick? One that gave you 76% eff. throughout the run, or 65% eff. throughout the run?

My opinion, 65% would be my pick(for kill setting). This is because you may be running into the surge limit in some of the RPM band. To stay out of surge and maximize the turbo, the right side of the map is where it at. Another way to look at this is when set on kill, you would be at 65%. I would think not to many run there often.

Think about worse case. Regardless of nitrous, you would like to spool as fast as possible and have it somewhat fun to drive, that is if you chose to street drive the car. With good intercooler and running meth, I would think you can give up a lot of that efficiency. If this was the highest pressure ratio you decided to run than I would go smaller. If you decide to push it further than your selection may not be that far off.

Allan G.

 

[Fryguy]

Just pretend for a moment that every other factor had been worked out and the only decision you had left in front of you was the two efficiencies. Which one would you pick. Absolutely no concern with how you were going to have to spool it up. Simple question.

It's a simple question, but a stupid one. I always choose the parts to make the car run the number I need to run, period.

 

[Alky V6]

That's not really how I build cars. I always pick the number I want to run first, then figure out how much power/rpm I will need to run that number. Then I pick the turbo/engine that will make the necessary power/rpm.

I normally build some amount of "scale-ability" into the combination so that I can step up if necessary, but I've been playing with cars for many years and doing it this way seems to make the most sense for me.

We'll talk about scalability with my combination in a moment.

 

[Alky V6]

It's a simple question, but a stupid one. I always choose the parts to make the car run the number I need to run, period.

A stupid question? So you totally ignore efficiency? Maybe I was wrong. Maybe you don't know how to read compressor maps.

 

[Alky V6]

My opinion, 65% would be my pick(for kill setting). This is because you may be running into the surge limit in some of the RPM band. To stay out of surge and maximize the turbo, the right side of the map is where it at. Another way to look at this is when set on kill, you would be at 65%. I would think not to many run there often.

Think about worse case. Regardless of nitrous, you would like to spool as fast as possible and have it somewhat fun to drive, that is if you chose to street drive the car. With good intercooler and running meth, I would think you can give up a lot of that efficiency. If this was the highest pressure ratio you decided to run than I would go smaller. If you decide to push it further than your selection may not be that far off.

Allan G.

This starts to run into the scalability, as fryguy put it, of my combination.
Before picking out a turbo, I agree it's very important to look at the compressor map from all possible operating conditions. But did you really study the comp map I posted? Look at the surge line. It's pretty unique for a 91mm turbo. Tell me what you think.

 

[Fryguy]

A stupid question? So you totally ignore efficiency? Maybe I was wrong. Maybe you don't know how to read compressor maps.

If we were discussing this in person, I could try to speak very slowly. With this being the Internet, I'm hoping you can just re-read what I type if you can't understand it

 

[Alky V6]

Here's the comp map again.

 

[Alky V6]

If we were discussing this in person, I could try to speak very slowly. With this being the Internet, I'm hoping you can just re-read what I type if you can't understand it

I understand that you can't answer simple questions very well.

 

[Alky V6]

How much horsepower would it take my car (3290 lbs) to go 6.80 in the 1/8 mile? Can anyone help me with this?

 

[Alky V6]

680 rwhp? Close enough.
That would be 800 bhp assuming 15% drivetrain loss.
My car did 6.80 at 8 psi boost. NO SURGE!!! That would be about 1.5-1.6 PR on the comp map.
Airflow would be a minimum of 80 lbs/min through the compressor.
Please take the time to map that point on the compressor map I just posted.

What is the efficiency?
Where is the surge line in relation to the point you just mapped?

 

[Dusty Bradford]

I race plenty of V8s during my testing at the track. They know they're in for a whoopin' when I come up against them. No rules.

I remember beating plenty of them with a 10.80 daily driver too. What does that have anything to do with this discussion. You should try a heads up class that has no rules and see how you fair. The record for a 6 cylinder with a 91mm on nitrous and 10.5's is probably 7.30. No rules.

 

[Alky V6]

Let's say I was off in my rwhp guess. Let's say it's only 600 BHP
That would be a minimum of 60 lbs/min of airflow through the compressor.

Please take the time to map that point.

What is the efficiency?
How close is it to the surge line?

 

[Alky V6]

I remember beating plenty of them with a 10.80 daily driver too. What does that have anything to do with this discussion. You should try a heads up class that has no rules and see how you fair. The record for a 6 cylinder with a 91mm on nitrous and 10.5's is probably 7.30. No rules.

Dusty,... Let me ask you this question. What does class racing have anything to do with this thread?

 

[Alky V6]

Now. Take that estimated 1180 bhp at a PR of 3.0.
180 lbs/min minimum at 3.0 PR. Please take the time to map that point out.
What is the efficiency?
Draw a line from the first point we mapped out through this point and onward to the 4.0 PR row. What is the efficiency at this point?
Now come straight down to find the lbs/min for this new 4.0 PR point. What is the lbs/min for the 4.0 PR point?
Now that is the definition of scalability.