Modern Muscle Performance Ported TB (Beta Test)

I never really thought the power to cost ratio was worth upgrading the throttle body on an NA car. seen too many disappointments on a dyno. unless having a fully modified head with prot and valve work I never recommended it to anyone. Now if it is Boosted where the engine is being force fed air instead of relying on the engine vacuum to suck the air in past and through the throttle body then I have see differences. this also is seen on the engine dyno I posted, on an NA application with stock head the gains are 3-6whp where as the same engines in boosted form gain what you see on the dyno and this is with no fuel/timing/KR adaptation clearing.

When I am boosted I will most likely dyno something like this on my car. Just for the sakes of my own data.

Originally Posted by SH4DY

Gary, when you are openly critical of someone how could you not expect some kind of kick back? And how can you knock this when there is a thread on here about you offering basically the same thing?

I understand what you are saying and I again appogize for coming across as critical of anyone personally. I just see stuff posted that I know from many years of experience, is suspect. As you may have noticed I also post very late at night after a 14 hour work day, so I don't always take a lot of time to consider my wording. With regard to selling the same product, I was aproached by someone here and asked if I was able to bore the T.B.'s, I said I was but that I didn't think there were any gains to be made with a stock engine. I still feel that way and I have never promoted that work here or anywhere else.

selling a product that, according to you, is only beneficial for 600 rpms?

I'm not sure I understand this statement.

I see what you mean, but there's still some variables.

If you increase the efficiency of airflow through a venturi, (Which I believe the TB would qualify as with the modifications discussed) there might be lower flow losses at all valve openings. (I consider the TB plate a valve)

I agree, the TB is a venturi, whether stock or modified. I'm not sure that I understand your valve opening reference. What I was saying is that if you increase the size of an intake valve, it will allow more air into the cylinder on every intake stroke at wide open throttle, regardless of rpm. The airflow through the throttle body is a function of rpm. A hypothetical perfect engine that makes 200hp and consumes X amount of air at 6000 rpm, will make 100hp and consume 1/2 X amount of air at 3000rpm. If the T.B. does not restrict air flow until a .9 X flow rate (5500rpm), then any T.B. related losses will occur above 5500rpm. If you then increase the size of the T.B. until it does not restrict air flow until 1.1 X flow rate (engine requirement at 6600rpm), you will recover the losses from 5500-6000 rpm, but have no effect on flow or hp below 5500 rpm. That is why when I see a dyno graph showing a T.B. mod that makes the same torque increase at 2800rpm as it does at 6000rpm, I become skeptical. I just am not aware of any law of physics that supports that type of flow behavor. I'm also supporting my view with the backing of 15 years of dyno testing all sorts induction system mods.

Consider this as well.... BMW spend millions of dollars on R&D. They developed a very sophisticated variable valve timing system, engine control electronics, DISA system, etc, etc, do you honestly think they left a free 5 hp sitting on the table by under sizing the throttle body. With a drive by wire system, there is zero negative effect and zero additional manufacturing cost to slightly over sizing the throttle body. Again, I am referring to potential gains on a stock or very lightly modified motor. Ported heads, cams and headers are a different story.

After reading my last two post I realize that I speak (type) in straight technical terms that may come across as critical of the person to who's post I am referring to, or even come across as arrogant or preachy. If anyone takes anything I write that way, I am very sorry. I'm just a technical person and I tend to speak that way.

My hope is to be a positive contribution here, not to make enemies.

Thanks,

Gary

Originally Posted by MotorMan

I agree, the TB is a venturi, whether stock or modified. I'm not sure that I understand your valve opening reference. What I was saying is that if you increase the size of an intake valve, it will allow more air into the cylinder on every intake stroke at wide open throttle, regardless of rpm. The airflow through the throttle body is a function of rpm. A hypothetical perfect engine that makes 200hp and consumes X amount of air at 6000 rpm, will make 100hp and consume 1/2 X amount of air at 3000rpm. If the T.B. does not restrict air flow until a .9 X flow rate (5500rpm), then any T.B. related losses will occur above 5500rpm. If you then increase the size of the T.B. until it does not restrict air flow until 1.1 X flow rate (engine requirement at 6600rpm), you will recover the losses from 5500-6000 rpm, but have no effect on flow or hp below 5500 rpm. That is why when I see a dyno graph showing a T.B. mod that makes the same torque increase at 2800rpm as it does at 6000rpm, I become skeptical. I just am not aware of any law of physics that supports that type of flow behavor. I'm also supporting my view with the backing of 15 years of dyno testing all sorts induction system mods.

Consider this as well.... BMW spend millions of dollars on R&D. They developed a very sophisticated variable valve timing system, engine control electronics, DISA system, etc, etc, do you honestly think they left a free 5 hp sitting on the table by under sizing the throttle body. With a drive by wire system, there is zero negative effect and zero additional manufacturing cost to slightly over sizing the throttle body. Again, I am referring to potential gains on a stock or very lightly modified motor. Ported heads, cams and headers are a different story.

He is very much right, throttle body size requirement is directly related to a single cylinder's mixture volume multiplied by RPM. The intake in our cars acts as a sort of buffered system for airflow. This means that until demands of all cylinders (raised by spinning at higher RPM) exceed the supply of air in the intake you won't see a gain from a bigger throttle body. The place where I still think they could be beneficial is where rev limits are raised or in the case of the m54b30 manifold swap on M52tus where engineers may have not have originally needed or wanted a larger throttle body to decrease velocity in a system already bottle-necked by the intake.

Gary,

I understand your example, but I believe there are too many dynamic situations within the discussed engine to totally agree in theory.

I've never played with the M54B30 throttle body....after being around Le Mans cars with 38mm restrictor plates...I kind of started looking elseware for power gains on my own projects.

Anyone that's spent considerable time on either an engine or chassis dyne will know the scope of variability that can occur. As a result, I'm skeptical of my own testing numbers....instead choosing to view the dyno as a design tool rather than a true measurement device.

I'm not knocking the product being discussed.....just sharing my point of view on the variability of testing and how engine theory doesn't always explain everything.

Gary, I get it that you are a technical guy but you can't say something doesn't work because the math doesn't support it. If that were true bench racing is all that there would be... I think PIE330 and I are on the same page about engines being too dynamic with too many variables to leave it strictly up to calculations.
The 600 rpm comment was in response to your saying the additional airflow would only be beneficial in the top 10% of the rpm range.
Look, this isn't going to be settled on an internet forum. I'm hoping some people will give one of these a shot and we can get some more results to compare.
And again, like I said earlier the part throttle changes (where most of the meat is taken away in the porting) in drivability and power really are impressive. I spend most of my driving time under 4k and half throttle and that's where I can tell the biggest improvement.

It certainly is going to feel better at lower revs since essentially your getting wider openings faster. That's one part of bigger throttle bodies that is well documented. I also agree with the notion that given wide variables in engines especially when an engine is no longer stock, it becomes hard to say what a throttle body will do unless we know all the variables. Again, Motorman is right though, it comes down to the volume of air going into one of the cylinders multiplied by rpm. That will give your air requirement. The problem for us is determining this volume without very specialized tools and knowledge and it is here where a larger tb may become a worthwhile change to try on a modified engine. I do think it's safe to assume the stock throttle body size is large enough on any modern stock engine. As mentioned, the manufacturers have no reason to leave such easy power on the table. However it is in their best interest to not exceed the requirement for throttle body size on the stock engine by much for improved drive-ability.

In the end, I think what's being argued here (or at least what keeps being protested) is the concept of engineering by formula/science and the concept of engineering by trial and error given the premise that we can't possibly know every possible outcome. I don't think anyone here would suggest to use one method exclusive of the other.

For people who wonder what size is the Stock and MaxBore TB...

Stock butterfly 67.5mm
Maxbore butterfly 72.1mm

-Trip

I'd be very interested in seeing the MAF readings before and after throughout the entire powerband before any additional tuning takes place.

it is worth remembering that an engine is not a steady flow system, the closing and opening of the valves, motion of the piston, exhaust function etc etc create pressure waves in the system. The throttle body and tubing leading to the plenum can affect these waves and the important parameters are length and diameter change these waves and hence cylinder filling. This is without even considering flow. This is why too large of a throttle can reduce power in certain parts of the rev band and increase it at others.

Originally Posted by smooth1

I'd be very interested in seeing the MAF readings before and after throughout the entire powerband before any additional tuning takes place.

I too would have liked to seen this. You would be amazed at what you can see by looking at raw MAF data. Some times the gains or losses are too small to see but it is good data to look at if you have the means.

Originally Posted by F1004fun

I too would have liked to seen this. You would be amazed at what you can see by looking at raw MAF data. Some times the gains or losses are too small to see but it is good data to look at if you have the means.

Ya, it'd be very good data to see. You can see the VE curve of the engine and you'll know whether or not changing the TB effected that positively or negatively.