Throttle Body Size
 

Hi,
I want to install new throttle body and spacer on my 86 gt 5.0L but wasn't sure of the size to use on the stock motor. I have a BBK air induction system on it already. Should i stick with BBK?
Any help and tips is greatly appreciated.

Thanks............Gus thumb:

Hello Gus,
You would probly be good with a 70mm, no sence doing a 65 since you might upgrade in the future and 70mm is really all you need.
Yes my suggestion is to buy the 70mm BBK.
Awesome TB I have the same one and no complaints.

Keith

id get the 75m if i were you i dont know if they have them for 5litres but yes i would go for the bbk ones...

i got the tb and spacer on my car as well sounds great when u hit the gas and i did notice a diffrence as well in the pedals sensitivitythumb: great mod!

On a mostly stock motor I would stick with a 65mm TB, anything larger will just cost you torque.

^I agree 100%, 70 or 75mm are WAY too big! a 60-65mm would work well.

I realize there might be some bottlenecking there, but what if he does other mods in the future? like H/C/I and maybe a turbo / S/Ger then he has to upgrade no?
Just a thought.....

I was going to say 65mm but I thought of future mods...

I still have a 65 on mine with H/C/I and a blower, and it still hauls ass.

Nothing to do with bottlenecking.
It's just that 70mm+is way too big for a stock or mildly modded 5.0. You will lose more than you gain if you put on a TB that big.
Would be like putting on a 4" full exhaust, power will be lost instead of gained. no:
More is not always more.

Good point ;) I never thought of it that way....Must be that saying kicking in (Bigger is always better) wall:
Ill keep that info to pass on to someone else.
Thanks

Thanks everybody for the great advice. Think i'm going with the 65mm.

Thank Again.............Gus

Hope we were all help to all.
Be sure to keep checking in :)

I like Accufab.

^Yes, Accufab makes a great TB, awesome quality.

You match the TB to the intake you are running. It's that simple.

For example, if you are running a stock intake, leave the stock TB on there.

If you are running an intake with a 70mm opening, then you run a 70mm TB and spacer.

There is no such thing as running too large a TB. This has been TESTED by many guys, one of who is Jay Allen, who ran a 90mm on Red Death.

The "myth" about TB size is a carry-over from the days of carburetors, where, if you ran too large a carb, the air velocity wouldn't be adequate enough to keep the fuel suspended and it would puddle in the intake. This used to cause all kinds of drivability issues and often caused the cars to be slower. Guy would stick on a smaller carb like a 650, the car would go faster and thus the other carb was "too big".

EFI is a dry intake system. The only thing you are controlling is air flow. You want as much of that airflow as possible. Making the throttle body an obvious restriction is a BAD idea.

I run a 75mm on my TFS-R and it works beautifully.

Very good point Chris, that almost sounds like common sence goodpost:

It's not a myth at all, it's a fact, an oversized TB will hurt power-I have seen it and done tests myself. So regardless of what Jay Allen did it makes no difference to me and my findings.
You have seen tests on it with different results from the tests I have seen then. Even with a stock intake (with ported inlet), a proper-sized TB can help power and a TB which is oversize will hurt power.

Please come argue that with Jay and the other "go fast" guys then. Seriously. A TB that CORRECTLY matches the intake opening (isn't causing reversion because there's a big-ass lip there because the TB is a bit bigger than the opening it's mating against) is the CORRECT TB for the intake.

The Explorer engine has a 65mm TB on it stock, but power-wise, were basically identical to our antique "HO" engines. Look at the size of the TB's on the Vortec and LSx engines, HUGE.

Unless you've been faster than Jay with similar parts (I know I haven't) then I'm going to take what he, and his decades of experience with this subject (and others like it) over yours. No offence to you, but he actually gets into the topic of flow dynamics and the like.

But if you are confident in your opinion on this, then lets debate it. Come over to SBFTech and we'll have it setup in the Myths and Rumours section and this can be discussed in a logical, and professional fashion.

Not trying to be a dick at ALL, so don't take it that way. I just feel Jay is right on this topic, his logic makes sense, and since you don't agree, I'd like to see this discussed.

EDIT:

I've gone ahead and asked for this topic to be discussed over there. I think this could be a great little debate, so Ponyryd, do you want me to link you to the thread when it's up or?

No thanks, I don't care THAT much about being right, and as I said, I don't care what Jay Allen says, and don't even know who he is.

And no, I will not follow you around the net debating a topic which you have clearly already made your mind up on.

I don't know why you NEED to be right about things and what Jay Allen knows, etc.... but feel free to update the thread on your findings. I'll stick with a 65mm and if others take my advice, that's fine with me.

BTW, I'm quite sure the Explorer V8 had quite a bit more power than a Mustang 5.0, otherwise why would Ford waste all the money on better induction and heads on it? Maybe you're using the wrong specs? the Mustang in '93 made only 205hp compared to a year before when it made 225, due to different measuring standards.

I too am not trying to be disrespectful-so don't take it that way. But I don't live on the internet and have much better things to do with my time.

The Explorer was 210HP and 280lb-ft for the GT40 headed 302. Remember, it's cammed differently from the HO because of it's added weight.

FWIW, Jay Allen is a cam grinder from Michigan. He runs seminars that many members of this board, a well as GTAMC have attended. One of his goals has been trying to dispel rumours, myths and half truths that people have learned from the "Internet Experts" as well as at lot of the "old timer" stuff. I honestly think you might learn something if you came over and actually read some stuff.

I don't NEED to be right about everything. Just, on this topic, I feel I am right, and you are wrong. My reasoning has a lot to do with what I have discussed with Jay, his tests, as well as others, and the results of how my car behaves with the 75mm on it.

There are times when I feel I am right. There are times when I feel I am right and discover I'm wrong. And there are times when I re-read what I said and realize I'm wrong to begin with.

I do kinda "live" on the internet, being a Network Engineer...... Computers ARE my business, so being on one all day......... Anyways, no disrespect taken, but if you don't mind learning stuff, I WOULD appreciate you coming over to SBFTech and listening to what Jay has to say. Chad (from Misener Motorsports) knows Jay quite well, so it's not some random dude on the Internet that nobody has ever met ;)

My buddy schlodes ported a stocker to about 63mm for me - it was on my 86 when I went 13.2@102 with a mostly stock 300,000km stang (gears, pullies, ported stock headers, stock h-pipe run open, and 9 year old at the time mt et streets) - and that was with the E6 heads!

Thanks again, but no thanks.

I'd say that 90% of what I have learned is from doing. I'm sure you'll understand that I'd rather not be taught things I already know and that have worked for me and others 100 times over.

In all honesty, debate is cool and I have no problem with it, but I don't get into heated debates on the net anymore-not worth it at all and nothing ever gets solved.
I even remeber debating with you the differences between import and domestic vehicles, to which I came away thinking you would never own anything but a Ford (or other big 3 vehicle), only to see recently that you are a German vehicle fan...........

Really though, just sit back and think about it, more air=more power right? Well if you can cram in more air, why not do it? A bigger TB will flow more air, plain and simple, even if the Intake is now the restriction, the TB has helped. Like you said though, it needs to match the intake. But it not only should match the intake, but the engine as well-stock engine, best off with close to stock TB.

If you feel you are right, that's fine, but going and posting it up on another board seems like an attempt to further prove how RIGHT you are and how WRONG I am seems excessive to me.

Just look at Scones for example, he ran awesome times with a mostly stock car and a bunch of elbow grease, no hi-po parts, just trial and error attempts on his own.

Yeah, Scones did have great results! I do recall another thread on GTAMC during one of our lovely import debates when I did mention that I liked BMW's as well. I've liked them for a LONG time.... So this isn't anything new :) I just don't like most Asian cars.

FWIW, a pretty cool example of "fast with Junk" was Red Death (brought it up earlier) which was built to prove a point..... Went 11.19 with STOCK GT40 irons, custom cam, Systemax II lower, box upper, 90mm TB and 4.56's. Pretty impressive stuff.

And I agree, our own experiences are often what we gauge future experiences/advice against. Another FWIW, I was told I would have HUGE "tip in" and drivability issues with my 75mm TB. I didn't. The 75 worked perfectly and behaved just like the stocker. I would attribute this to the big-ass intake it's on with a genuine 75mm opening on it (as I'm sure you have experienced, some intakes aren't what they claim to be; 70mm openings being more like 68mm...etc).

To me, there always seems to be something more to learn in this hobby, another trick or tip as to how to improve your performance/reduce your ET and the like. We are never done learning, and while I love the experience of working on my car, if I can improve that experience by following advice given to me by people who have been there, done that 1,000's of times and with EXTREMELY good results, then I will incorporate those things into what I'm doing.

That was my experience with the TB thing. The Internet Experts on the Coral were all saying it was too big. Jay's advice I had read in other threads (back when he still contributed over there) as well as others who genuinely seemed to be "with it", said otherwise. So, I bought the 75mm and it worked fine. But it IS on a big-ass intake.

IMHO, research is a lot more cost effective than trial and error in this hobby ;)

dude, your car did NOT drive like a stocker! Remember when trish used it for a week and would not drive it? she dumped it on me and took my stang. I can tell you it did not drive right, if you tried to cruise with it it would buck like "a wild stallion" you had to be at an idle or always into it to be able to drive it, and 300hp on stock tires is a handfull so she wouldn't drive it.

LOL! Yeah I remember that ;)

The bucking/surging wasn't the TB though, it was the TPS. When I fixed the TPS ground issue, it was fine. It originally didn't do it either, when it was up at DaSilva's being tuned, it was well behaved. It developed that a while later, and was doing it for quite some time until I figured it out. that problem had me freaking baffled for a while............. Anyways, it drove much like a stocker after that, and would start like one too. But when that problem was occurring, yeah, it was a HUGE PITA and pretty much only worked well at idle after it figured itself out, and then at anywhere above 1/4 to 1/2 throttle.

^Yes it is, but not always as effective. "On paper" doesn't always work in the real world.


^Entirely different topic, but it's still something I don't get.
You would fight tooth-and-nail about how great Ford is and all imports are crap (no matter what real-world evidence I presented stating otherwise), then you like a BM? Kinda hypocritycal IMO.
I guess I'm just saying to have an open mind a little. I too am up for a debate but as I said I don't spend a lot of time on-line, so it's hard to debate like once, twice a day. Plus, when I'm online, I do what I want and don't wanna feel obligated to "check-in" on what people are saying about whatever.
I never liked imports (but didn't hate them) 'till I got in the trade and the quality differences are unbelievable! (IMO). Believe it or not, I was a Chevy guy 'till I bought my first Mustang.................

I had the SAME problem when I put on my 70mm TB on my stocker, so I swapped it back but the problem stayed even with the stocker.....(Ended up being TB Gasket LOL) gotta love un-metered air.

I no were your coming from I am in the same situation.....i've owned AT LEAST 30-40 vehicles since I was 15, Im now 27 all of them being Chevy's.
My first ford was my Mercury Goes Fast, I bought it for a winter beater.
Then I bought my Mustang.
I think I will stick with GM's other cars over Ford's, like seriously look at the Focus base model and then look at the cavalier way better design.
Thats just me.
I use to hate Honda's, but when your up in the city like Toronto/Hamilton you better have a fast car, and you better be ready cause the Honda's are fast for what they are :)

I can see were PonyRyd is coming from, It would be like the same thing putting a Fully Ported aluminum lower intake manifold on stock heads (Well not that extreme) but there will be a resistance.
Or like putting a fully ported upper and lower together and not port matching the gasket, so theres going to be a slight "piss poor flow"
UNLESS you port the opening on the stock upper, I don't think I can agree with you sorry Chris, maybe Im getting the wrong picture. wall:

Post the link to the thread Chris I myself would like to look this up.
run:

Keith, I said match the TB size to the opening on the intake, which is exactly what you are saying. My intake has a 75mm opening, so I run a 75mm TB. If your intake has a smaller TB opening, don't run a TB that is bigger than the opening (unless you port it out to accommodate the larger TB) because that will cause reversion. We are on the same page here. And when the current topic over on SBFTech (347 vs 331) is finished, I hope Jay will make this the next one, and, as promised, I will link it here. Should be a neat topic, and I'd like to see other people's views on it.

LOL! I see you've met engineers before :) This is VERY true, not everything on paper works better. That's typically why I look for info that there is actual proof of it being done, and done with great success first.




It's not hypocritical, I feel the Japanese, and many other Asian car manufacturers rip off other people's engineering. The Germans have been very much the pioneers in MANY different areas, including cars. And it's not necessarily the cars behind it, but much of the attitude associated with many people in that circle I guess. Calling Japanese cars "high tech" because of various technologies that they will attribute to Japanese invention, but in fact were invented decades earlier by other manufacturers.

A couple of examples:

Variable Valve Timing. Invented by a German engineer, originally used on steam engines.

Electronic Fuel Injection. Ford used EFI (and SEFI) long before Honda did, as did I believe GM.

Overhead cams. Ford was using these in the 60's. The DOHC Indy Cammer is one example, as is the 427 SOHC.

I guess in retrospect, it's not the cars I hate per se, you cannot really, with any respect to sanity, hate an inanimate object. It's more the attitude of those who own them (and yes, I am generalizing, obvious an 80 year old lady who loves her civic isn't wielding an attitude).

Most technology is borrowed in one way, shape or form. Ford didn't invent the automobile, they didn't invent overhead cams, and they definitely didn't invent fuel injection. But Ford was making cars when Mr. Honda was still a child. Hell, if I remember correctly (and I might be wrong) but Ford was using overhead cams when Honda was still making motorcycles and cars weren't even considered yet!

But you talk to any Ricer and the Japanese invented EVERYTHING and anything domestic is super low-tech and WAY behind in EVERY WAY. Meanwhile, they could be driving a mid 80's carbureted prelude......

Is this helping, or am I just making things more baffling in regards to how I think?

Not that hard to believe, many people start off with a Chev. My first car was a '74 Cutlass Supreme, closely followed by an '86 Olds Custom Cruiser Wagon. My grandfather bitched my father out for buying a GM (my mom's dad) and told him to go buy himself a Lincoln. He did. it's the one I have now. It outlasted the Wagon by almost a decade thus far........ And that's all my dad will own now. My grandfather on the other hand, an Engineer for GE, was an absolute Ford NUT, often retrofitting his wooden boats with Ford powerplants. We hung out often :)

^Well, I agree with you there, but many (myself included) people like the cars for the simple fact that they like them. I like the way they drive, handle, hold resale, etc.....I am not a "ricer" though, and I don't think they are responsible for inventing anything outstanding.
That can be said for anyone really, Ford guys, SRT-4 guys, Jap guys, Euro guys, etc....they all seem to think they're the best no matter what-this is the wrong way to think IMO.
Plain and simple, I like many, many cars and never limit myself to a certain region or manufacturer for what I like and may buy. In the end I guess I'll buy what's right at the time.