I agree completely, the in flowing air is going to deflect off of the smaller diameter intake inlet and cause unwanted resistance. When I posted before, I meant to say that as well. I just meant that if you have the 70mm opening, you should/could run a 70mm TB.YEAHLOH95 said:my only ? why put a 75mm throttle body on a intake with only 65mm? opening? if you anything about flow you would understand why this is bad, it may not hurt power output that much but a 65 would make the same power .its called an sudden contraction and it hurts air flow ...
5spd GT said:Right.
Interesting, I swore a diesel had an intake tube track?
Well you better hope that engine can withstand to be revving to 6,250 bouncing off the limiter. It would not run fine.
A bigger straw has a more dispersed area of incoming (blowing) air. A smaller straw (throttle body) has a more concentrated hit of air. Make sense? Sure it controls it but not as concentrated.
You will lose velocity (concentration) and that is key for overall driveability. A 75mm TB will give you a goosy feeling (especially in the lower gears). Some like it, some don't. I'm sure your AFW makes up for that off idle...
A 75mm TB does have an effect on incoming air. Many more cc's of air come thru
273's wont' effect driveability. It is a set gear ratio that doesn't vary. Your AFW, tune, TB could very well be those effects.
a50sn95 said:As long as you can TUNE for the additional AIR, it makes NO difference, in my opinion.
That's why there are settings for TB Airflow, Neutral Idle Airflow, and so in in your EEC. Change anything in the intake tract, and those numbers need to be changed.
You'll noticed that I've already mentioned that when I said what I said...
a50sn95 said:My only issue is to make sure to rev it high enough to get the car rolling. If I don't, it'll stall. That's due to the gears and flywheel.
a50sn95 said:What's an AFW? You mean flywheel?
a50sn95 said:A diesel will have a tube from an air cleaner to the throttle opening, but there is no throttle body. Engine speed is controlled by fuel. It'll run the same with out the tube. (Think OLD John Deere Johnny Popper, not a Modern electronic diesel.)
a50sn95 said:As long as you can TUNE for the additional AIR, it makes NO difference, in my opinion.
That's why there are settings for TB Airflow, Neutral Idle Airflow, and so in in your EEC. Change anything in the intake tract, and those numbers need to be changed.
You'll noticed that I've already mentioned that when I said what I said...
5spd GT said:You can dremel out the intake opening a bit but it still can only breathe as good as the upper intake initial trac.
5spd GT said:That is due to your flywheel, not your stock gears than came from the factory. It didn't have the problem before. Don't blame it on the gears.
5spd GT said:So your talking "old school" when we are talking the new age It's like comparing TB's too carbs
5spd GT said:Your engine can only support so much air, so their is a limit on both sides of the fence that you can tune for.
5spd GT said:Not everyone has the funds or availability to tune everytime they do a mod.
a50sn95 said:EXACTLY! By putting the 75mm on there, now it's NOT the restriction anymore, something else is. The heads or the intake or the MAF or the intake tube or the air filter, etc.... So on a stock engine you MAY get more air, but it really depends. So, then, how can it really matter if the TB is 5 or 15 mm bigger? The engine is STILL drawing through a straw.
I'm just saying, why put a 65 on there if you are going to keep adding mods? You'll be replacing it again, and my OPINION is that they'll work the same.
a50sn95 said:It's not really a blame thing. I don't view this as a BIG issue. It just needs a few extra hundred RPM...
So you don't think a set of 3.73's would make it a little easier to pull away from a stoplight.....?
a50sn95 said:Hmm TB's and carbs don't compare, and I didn't SAY they do. I was comparing a fuel injected engine to a fuel injected engine. Diesels don't use TB's to control rpm. Gasoline engines do.
Ayway the ORIGINAL point was that a gas eninge could or could not run without a TB. I say it would (assuming you could get it started). It would be no different the HAVING a TB at WOT.
a50sn95 said:I don't know what you mean here. Say your engine needs 43 kg/hr of air to run at 2500 rom (making up these numbers). So with a 60 mm tb you have to crack open the TB, say 20 percent to get this. So now you put a 75mm TB on it. All I see is that you now only have to open it 15 percent.
So like I said, the ONLY time it matters is WOT, and the transition to WOT, which I say can be adjusted in the tune.
a50sn95 said:I use a Tweecer R/T. Only costs me a little time to change my tune. AND I can DATALOG the results to make sure I understand what I just did.
5spd GT said:If your computer literate and have extra money running around. You could save that $800 bucks and by something that is more needed than using it on a simple h/c/i car for example. House payment maybe
5spd GT said:Well if you have a big insert of air from a throttle body. The merging of air will have to come from more of an extreme angle. More turbulence and uncontrolled/unconcentrated flow. That is my opinion.
5spd GT said:You were saying (and I can quote) that your takeoff problems were due to your flywheel and gears.
Yes, the gears will help. When did I say it wouldn't. Obviously the problem is the AFW because the gears worked fine from the factory and before the AFW. Easy figuring...
5spd GT said:You said: Think OLD John Deere Johnny Popper, not a Modern electronic diesel.
You were talking about "old" and then saying don't talk about the "modern". So why are you using an "old john deere johnny popper" when we are talking about "modern" EFI throttle bodies. What's your point? Engines act differently and have different internals and uses/needs. Why compare?
5spd GT said:Not everyone has the money, funds, avalability, time, to tune their car.
Yep, and the less crack you have to give the more goosy the engine can get in the lower rpms. Since the tps factors into the ECC the tuning factor needs to be addressed if applicable.
5spd GT said:If your computer literate and have extra money running around. You could save that $800 bucks and by something that is more needed than using it on a simple h/c/i car for example. House payment maybe
YEAHLOH95 said:my post wasn't dirrected towards anyone just wantedf to make a point . i'm just not on the bigger is better band wagon . i'm only running a 70 mm on my car til i switch to a fox set up then i'm not sure on the size i'll use maybe a 65mm???.
final5-0 said:Would you please confirm my understanding of what you were saying above
I think you were trying to get across the smallest part in the air path is gonna determine airflow
OR
That smallest part is where the greatest restriction is gonna be.
Sooooooooo
Say you got a
80mm maf
75mm tb
70mm elbow
75mm intake opening
The larger tb & intake opening is doing you no good due to the smaller elbow.
Do I have a correct understanding here
Grady
a50sn95 said:Ok, you can have your opinion.
a50sn95 said:Yes, my takeoff problems are due to the combination of a light flywheel and 2.73 gears. I don't know why we are arguing over this.
a50sn95 said:Again, the point was that an injected engine would run without a TB.
a50sn95 said:Oh well, if you WANT to play with these engines, sooner or later you're gonna need a tune.
a50sn95 said:Again, it's your opinion. 800.00 would even come close to my house payment.
a50sn95 said:Anyway, this is getting tiresome. I don't think you are right. Others have said they've done it, and it didn't seem to bother their cars. You don't think I'm right. I'm getting tired of "discussing" it.
It's far from the original post, anyway...
You can make the last post so :Teh-Win:
Stang95fyvo said:Someone mentioned above that if you increase the opening size then you are getting into a more turbulent flow and that the air will be less concentrated.
Actually it is quite the opposite. If you increase the velocity, the flow becomes turbulent, and this is due to the density, velocity, diameter of the pipe and the viscosity of the air. I am a Mechanical Engineering student and was actually just in a course regarding fluidic flow.
So in order to keep the flow laminar and more concentrated, one would want to increase the throttle body size and slow down the air movement. However the part about a sudden contraction IS correct. A sudden contraction will cause less flow. So I would agree that if you have a 70mm opening, get a 70mm TB. And the same for a 75 mm opening and TB.
final5-0 said:Would you please confirm my understanding of what you were saying above
I think you were trying to get across the smallest part in the air path is gonna determine airflow
OR
That smallest part is where the greatest restriction is gonna be.
Sooooooooo
Say you got a
80mm maf
75mm tb
70mm elbow
75mm intake opening
The larger tb & intake opening is doing you no good due to the smaller elbow.
Do I have a correct understanding here
Grady
5spd GT said:So if we want to get less concentration (more turbulence) let's port the lower intake "long and wide" and the intake side of the heads and install some bigger valves. Let's see if we lose any driving characteristics (showing a bit more extreme case to example how concentration/velocity is important).
If you enter to much dispersed air you lose velocity/concentration and under WOT (until the engine catches up with the incoming air) your going to lose a torque response, more so in the lower rpm powerband IMO.