Only other upgrades were Exhaust, CAI, MAF, UD pulleys, and tuning the timing and fuel pressure. Gained 30 peak RWHP at 4700 RPM with a 43 RWHP gain at 5100 RPM's .
I always have been told 75MM TB is way too big for a stock engine, but these results seem to disagree.
It may be too big for a stock motor but since you're using the factory spacer plate (I'm assuming you are) and the factory intake manifold, it should balance out considering you are still essentially pushing air through a 60 mm opening.
Put a larger bore spacer and intake on there and then you'll see how it's too much.
Did you have it dynoed?
Its not my car, Here is a link to the article.
Link (http://"http://www.mustang50magazine.com/techarticles/m5lp_0701_1993_ford_mustang_bolt_on_buildup/index.html")
They use a 75MM EGR plate too and grind out the stock intake opening.
WAYYYYYYYYYYYYYYYYYYYYYYY to big for a stock 5.0L.
What would be the benifit????
I think the only reason they saw so much gain was because they did all that other stuff at the same time. Hell, the UD pullies were probably worth 15 hp alone.
I doubt the huge TB helped all that much more.
I agree.The 75 is to big.I would bet if you pulled it off,installed a 60 or 65,it would be the same HP.If you install a larger than stock throttlebody,the hole in the intake needs to be opened as well,otherwise,it's totally defeating the purpose.
Well i don't know you would have to ask them why they did it, but it obviously didn't hurt anything. I don't have any plans to put a 75MM TB on a stock H.O. I just found the article and thought it was interesting.
I will put on a 75MM TB when i install my TFS top end kit though.
I run a 70mm on my supercharged HO and it is plenty good for upto 500hp,stick with a 70mm you don't want to hurt low end torque.
I'm starting to disagree with that old assumption. Read why here: http://sbftech.com/index.php/topic,5732.0.html
More on this here: http://sbftech.com/index.php/topic,6484.0.html
Well before reading Paul's links, If you look at the dyno numbers it didn't hurt the low end torque numbers at all.
I don't understand how it could hurt low end torque anyway.
It will flow more air than necessary but the more air you can get in = more fuel you can add = more power. You cant hurt anything by having too much air in the cylinder. After all the engine is just a big air pump the more air in the more power it will make
it isn't only the AMOUNT of air you can get in, it is also the velocity, and if you hurt the velocity, you WILL lose bottem end torque. Dont belive me? Take a stock output 5.0L and add an open plenum 4bbl carb intake to it. now lets see how much fun it ISN"T cruising around town, with that intake over the stock one. Ask me how I know this.......
True to a certain point. Running big heads with something like 14 pound injectors at stock pressure may be an issue though....
The more air you give it the more fuel it needs.Then you got to get rid of the result.Exhaust.
Not talking about S.O. or carb. I am talking multiport EFI with a stock intake, or any aftermarket EFI intake. Actually if you read the links that Paul posted the next to last post, he put a 80MM TB on a SD engine with absolutely
no problems
http://sbftech.com/index.php?PHPSESSID=8c3450ee5f4bb72343de25286d224756&topic=5732.msg55243#msg55243 (http://"http://sbftech.com/index.php?PHPSESSID=8c3450ee5f4bb72343de25286d224756&topic=5732.msg55243#msg55243")
The exhaust has obviously got to be upgraded. How does a larger TB hurt velocity.(Don't mean to be a dick but I really would like a logical explanation or some sort of proof, I just cant see in my mind how it would hurt the low end. I do have an associate degree in automotive technology and from what i know about EFI, I cant make the connection between a big TB and loss of low end torque. I don't want to start an argument it is just the way my mind works) The numbers are right there in the article they didn't lose any low end torque or power.
Perfect example is 351 clevland 4bbl heads,the ports are huge(almost fist size)and it is dyno proven that down low (unless you have a blower to fill them up) they hurt low end torque big time,ie too much air for too little velocity and compression,the engine cannot suck in enough of the air to need that much flow.
Too warrant a 75mm tb you need alot more intake,head,camshaft and compression.
The engine has no need for that much airflow coming in.
Same applies to exaust going out.
If you stick dual 5" exaust pipes(like a 75mmTB) on a stock 5.0L you will hurt low end torque alot(not enough back pressure).
Your engine has the need to only take in what it can through the duct work it has,too a certain point yes you are right in saying the engine is just a big air pump but it does not just take in more and more air for the more fuel you give it,the other components must match.
If this was the case why not just put a 90mm TB on it and say well if i add 42lb injectors i should make 500hp(more air=more fuel right,wrong),not the way it works.
But hey if ya want to waist your money on a 75mm tb when you don't have the engine to support it be my guest,however you will notice a small loss in low end grunt.
If you want a logical explanation either go back to school or go back to planet vulcan lol,not trying to be a dick.
Not talking about ports on the heads. The heads have nothing to do with this question. Well i may have to go back to school for the explanation cause you certainly arent giving it. Unfortunatley the school i went to didn't offer performance classes it was all about what was required to become and ASE certified Technician. Not one thing you have said explains how it loses low end torque.
The question was: How does a bigger TB cause a loss of low end torque?
I haven't seen(or heard) anybody say i put a 75MM TB(or 70MM TB for that matter) on and it killed my low end torque. All i have seen is people say: That is too big you will lose low end torque, with no real evidence that I have found. Honestly I would appreciate it if someone could point me in the direction of the evidence that a large TB will cause a loss of torque.
Explain to me how air velocity at the TB has any effect on the air velocity at the lower intake and head intake runners if you are feeding the same cfm in?
from personal experience, me and a buddy use to race almost everynight after work in our stangs, both had the typical cheap bolt ons, (headers, exhaust, pullies CAI, gears, etc.) we use to be side by side with everyshift, the only way either one would win is if the other missed a shift. He put a 70mm TB on and thought he would rock me with it. Didn't work. Taking off I got a car length on him, and pulled on him with everyshift. He would regain the ground at the top end but you could tell he lost something with it.
That was all the proof I needed. and like dominator said, would you put a 5" exhaust on a stock 5.0L? doubt it. And I know you weren't talking about carbs. Fine you want an example of too much air hurting torque? grab yourself a Box style upper plenum and slap that on your stock 5.0L, watch what happens to your power. a 70MM throttle body will not do anything for a stock motor. MAYBE add 2hp on the top end but it will lose on the bottom. Most of the dyno sheets I have seen in the magazines have shown a loss (even if it is very slight) in the bottom of the power band after a big TB swap on a near stock motor, for a small gain in the top end.
1wldbrd:
Just curious did your friend upgrade CAI when he swapped the TB?
As I said, I have no plans of putting a 75MM TB on a stock H.O. I am just trying to learn how the TB would affect the air velocity to cause a loss of low end. It seems that Anderson Ford Motorsports (http://"http://www.andersonfordmotorsport.com/") agree that that there is no effect, though they were planning upgrading the heads,intake,and cam in the near future.
Velocity has everything to do with how a carburetor works and nothing to do with how fuel injection works.
The Venturi (named after a smart old Italian) in the carburetor uses the Bernoulli effect (another smart Italian) to make a carb work.
Pressure changes created by fluids in motion. Air is a fluid in this context.
A bigger hole in the intake will lower the velocity and raise the air pressure in the manifold. Less vacuum. So the air is denser.
K done with this thread,you guys are idiots,who here has a 500hp 5.0L....do i here crickets o yea that's right i do and i know what it takes to make hp.
I'm also a liscensed class A mechanic.
Why do you think nobody with real hp except me has posted in this thread,it's because you won't listen.
Velocity is important in any engine,not just carburated,who the hell told you it wasn't and where do you get your info,are you a tech,didn't think so,why is it that ford 5.0L trucks have longer intake runners,don't know the answer well let me give it too you,it's for more VELOCITY which = more torque duh.
Heads,cams,intakes,tb's,exaust,carbs are all relavent to what you ask but being the retard you are you just don't get it.
Seriously man you need to go back to school as you didn't learn anything about how an engine works!
Last time i'm gonna explain it:
To big of a tb,intake,head,cam or exaust WITHOUT the matching components will hurt low end torque and hp due to lack of velocity and being overly lean,the engine doesn't need the extra air so there for can't use it.
Single plain intakes,to big of a tb or carb,to big of an exaust all these hurt torque if not match with the proper components.
Read up on sites like the corral before you go posting stupidity without listening,god people like you piss me off!!!!
P.S. Air is not a fluid in any context unless it is compressed into liquid oxygen so don't use that one with me as it has no relivents here,the only fluid that goes into your compbustion chamber is fuel.
I am willing to listen.
If anybody else has something to add or something I should read about it I will gladly do so.
75mm tb is too big for what little that motor has done to it. my buddy who builds the quick 8 cars had a guy bring a 91 stang to him. he had trick flow upper and lower, e-303 cam, GT40's with a little port and polish work, and basically just about everything that's listed for that car they tested with, except he had an 80mm TB.
he was having problems with the car and couldn't get it under 14.9 and it was dead slow off the line. my buddy dennis recommended going to a 65 or 70mm throttle body and now the guy is running mid 12's(he did a little more tinkering, but downsizing the throttle body helped big time).
Your ignorance is showing. Look up fluid in your dictionary, assuming you can read a dictionary.
I found some information.
First is the fact the the TB they used in that article(Professional Products) is known to flow less than other 65MM TB. So that could be a reason that it worked well.
Second i found an article about choosing TB size (http://"http://www.accufabracing.com/article%203.htm").
as I said, it may not effect it as bad with EFI but it STILL LOSES TORQUE. And explain why we would need to upgrade the CAI when we both had them, re-read the mods I listed for the cars.
do it to your car and tell us what happens. I know I wont be surprised by your results.
More like YOUR ignorance is showing by thinking velocity has no affect on an EFI motor. go a head waste your money on a box style upper plenum for a stock 5.0L and TELL ME velocity DOESN"T affect an EFI. Try digging in to a car and gain some experience with air velocity before you comment like that.
WHAT !??? It will lower the velocity AND air pressure, NOT raise it.
Exactly! That's why you dont want to go bolting a RPM 2 or Systemax intake on a stock or mild engine combo. You'll kill your torque. A mild engine with a ported stocker will run all over the big stuff (on the same engine) up to 4K or so RPMs.
I know intake manifolds have a huge effect but I'm not sure how much difference there would be using a 65mm TB as opposed to a 75mm on a stock or GT40 style intake. Probably not much... That being said I think I'll hang onto my 65mm TB for a while.
I haven't read the rest of this thread but I think I might now.
Alrighty, I guess I'll jump in this now.
Well after reading the whole thread I started thinking about how EFI works as opposed to a carb. I think the main thing to remember is that the same rules don’t apply because a carb meters fuel based on the venturi effect. Too much carb kills torque because the lower air velocity is inefficient in mixing the gasoline with the air. Plus the intake, even in dual plane form, has relatively short runners and the fuel has to be kept in suspension through the intake so air velocity through the carb is critical.
A fuel injected manifold separates air intake and fuel metering functions so the same rules don’t apply to a certain extent. Air velocity is and always will be the major factor in torque production. However, in an EFI application plenum volume, intake runner volume and length are the 3 primary factors that dictate torque production. The EFI intake works on the prinl of ram effect. When the intake valve opens while the piston is traveling down to the bottom of the bore the column of air in the intake runner along with air in the plenum is pulled through the head and into the cylinder. If the air in the intake runners is lazy (I.e. runner volume too big) you can’t pack as much into the cylinder at low engine speed thereby killing torque.
The way I see it is that the TB is the doorway leading to the plenum chamber. It’s the plenum chamber that feeds the intake runners. If your intake runners are properly sized it shouldn’t matter how much air is being allowed into the plenum by the TB. Why… because intake runner volume is what will ultimately dictate how much air and at what velocity it can be rammed into the cylinder.
Now with all that being said if you were to choose a throttle body based on the CFM requirements of an engine at say 6000 RPM a 5.0 would only need roughly 530 CFM based on the Accufab chart. If a 65mm TB is rated at 664 CFM wouldn’t that make it way too big for a 5.0? But in reality we know that a 65mm TB is worth more power than a 50mm TB without sacrificing torque down low.
IMO, the long runner Ford EFI intake design is the reason that proper TB sizing isn’t all that critical. Super ford mag did a dyno series a few years ago where they added one mod at a time and I’m sure they played around with TB sizes. I’ll have to see if I can dig that up.
I was waiting for someone to comment on the over-rating of the PP throttle body...also, it's not as if a TB alone gave the power...that MAF/filter/CAI from Anderson is KNOWN for being excellent at making more power on just about any N/A combo along with his tuning skills. The TB alone was only worth a few horsepower if you break it down.
Next, scientifically speaking, air IS considered a fluid due to the way it flows.
Loss of low end torque comes from a lack in either exhaust gas velocity or intake velocity(weather it's heads or intake), increasing the T/B size will NOT have a negative effect on low end....BECAUSE you are NOT changing the size or length of the intake runners or the intake ports in the heads....yes, you may have to optimize fuel pressure/timing and often times even upgrade the MAF meter.
Velocity depends on a few things...the cross-sectional area of the port or runner, the length of the port or runner, the shape of the port or runner, and valve sizing...NONE of those characteristics change when installing a larger throttle body...it's almost like saying a CAI will reduce low end torque.
Dominator, forced induction and N/A combo's are like apples to oranges when it comes to throttle body and intake manifold selection...a 70MM t/b will flow more CFM on a power adder combo than a N/A combo every time...WHY? Because on an N/A combination, you only have 14.7lbs of atmospheric pressure(@ sea level) acting upon the t/b and intake...in a forced induction set up, you not only have that same 14.7lbs, but you also figure that you're forcing extra air in via s/c or turbo...with 10lbs of boost, it's like having 24.7lbs total pressure...I'm not saying a 10lb s/c kit will give you a 24-25lb boost reading because gauges aren't calibrated that way.
10lbs through a 90mm t/b and a box style intake will blow away a combination with the same boost but stock t/b and intake WHILE UNDER BOOST....HOWEVER, you would subsequently need to change pulleys to get the same pressure acting on the combination with the larger t/b and intake. INTAKE VELOCITY IS COMPLETELY IRRELEVANT ON A FORCED INDUCTION SET-UP, WHILE UNDER BOOST . This is because you have something creating a much more powerful velocity for you.
Guys who cry about losses after large t/b's are usually the ones who add ONLY the t/b and egr spacer and do nothing about MAF meters, fuel pressure, and timing.
1WLD BRD- you make a very valid point in the fact that a box intake will kill low end torque on a stock motor, but we are NOT comparing intakes here...another apples to oranges situation.
Dogcharmer- Nice response!
I AM NOT TRYING TO BURN ANYONE DOWN IN THIS POST, I AM TRYING TO CLEAR THINGS UP SO PLEASE DON'T GET PISSED AT ME IF YOU DON'T LIKE WHAT WAS SAID.
-Don
I understend that, but he was saying intake velocity HAS NO affect on an EFI motor. I stated that to prove a point. If intake velocity has no affect, we would all be running a box style intake. ;)
And yeah good points both you guys. but look at the dyno charts they show in magazines, in alot of them, they do lose some lower end after a big tb swap. I dunno, :dunno: I still say a 75mm TB on a stock HO is like a 4" exhaust on the same car. Doesn't make any sense.
Guess I'll post my perspective as someone who has upgraded to a 65mm, then a 75mm and now an 85mm TB.
1) The size of the TB has little to no relationship to low-end torque on a long-runner tuned-port EFI vehicle.
2) If you do see a bog with a larger TB, it is due to the fact that the EFI computer uses rate of change of TB to add fuel during tip-ins. Imagine how much more air an 85mm TB can let in at 10 degrees tip-in versus a 60mm TB. Believe me, I have had the most issues tuning around this "lean out at tip-in" problem (S/C notwithstanding).
3) At the 330 RWHP level, Kenne Bell only got 4 HP switching from a 65mm TB to a 75mm TB ( http://www.kennebell.net/techinfo/ford-techinfo/blowzilla-flowzilla.pdf ). This is in-line with what you might expect on the typical 250-300 RWHP street engine where you would expect almost NO gain switching from a 65mm TB to a 75mm TB.
Interesting point... I would think that going a little lean on tip in would actually help on a naturally aspirated combo.
BTW, aren't you using a TwEECer. If so how's that going? I'm thinking about going that route when I get N2O and bigger injectors.
The TwEECer has somewhat of a learning curve, but once you are "hooked into" the lingo and realize the power at your fingertips, you will be very happy :o). There is also additional tuning software that this fellow http://webpages.charter.net/eecbuttstuffyzer/ wrote that helps buttstuffyze datalogs and makes recommendations for changes (EEC buttstuffyzer). He also just recently released a new program called Bin Editor that will let you burn tunes through the TwEECer and datalog on a different tab!! It basically replaces CalEdit and Calcon - the two programs that come with the TwEECer for programming and datalogging respectively. The cool thing is that it lets you change ECU paramaters that aren't even visible in the TwEECer software. There are more advantages, but you would just think I am talking jibberish at this point.
TwEECer + wideband O2 + EEC buttstuffyzer + getting help at http://eectuning.org/forums/ = a good tune :D
I dont know if you are referring to something i said or not but I was trying to get an explanation of HOW the TB affects the velocity so i could understand how it would cause a loss of low end.
This last page has been very informative so thank you to all of you.
I would like to expand my knowledge of performance engines. Anybody know of a good book on engine performance?
There are a couple of books specific to the Fox Mustang (applies equally to Cougars & Birds) and the 5L engine that I found very useful when I was just starting out:
"How to Build & Modify Ford Fuel-Injected 5.0-Liter V-8 Engines" by Tom Wilson
&
"Mustang Performance Handbook" by William R. Mathis
Both of these books cover the popular mods from a complete engine rebuild to just bolt-on items. The latter book also covers drivetrain mods including transmission & rear-end. The info is slightly dated, but still very useful - especially for a beginner.
BTW, if anyone wants to experiment to see the effects of switching to a 75mm TB, I have an Accufab 75mm TB and EGR spacer that I don't need any more - I'd sell it to anyone who's interested...
How much? I dont know if i would put it on stock but i would certainly use it when i put the TFS kit on.
No I was refering to softtouch's comment.
I have both those books too. As he said, good information though somewhat dated. My wife stole them on me though, as she bought, and is building a T-top '84-85 Capri. (cant remember the year)
Yeah how much for the TB and spacer?
If velocity didn't matter then why would Ford have designed an 18" ish runner?
I found this to interesting info about intake runners.
http://auto.howstuffworks.com/question517.htm