62mm throttlebody idle problems

[Dino Dino Bambino]

You have that dead backwards.

I was referring to the fact that the FRPP intake manifold would only be used with a centrifugal supercharger or a turbo if you wanted to add forced induction to a previously N/A build that already included the aforementioned manifold.
As for the TB size in such a forced induction set up, I agree that it's less critical than in a draw through supercharger set up.

 

[Granatelli]

Thanks for educating us on a few points.
According to my calculations, a 281ci engine requires 528cfm of airflow at 6500rpm and 100% VE. The stock dual 55mm TB flows 953cfm @ 28inH2O pressure drop, while the FRPP dual 62mm unit flows 1306cfm. Both seemingly flow much more air than the engine needs at 6500rpm. The difference is that the 62mm unit can flow the required 528cfm at a lower pressure drop:

55mm TB: 528cfm @ 8.6inH2O
62mm TB: 528cfm @ 4.6inH2O

Basically you don't need to suck as hard through a bigger straw to draw air at the same rate. However in most circumstances, the stock TB is already a big enough straw to begin with.

RESPECT.

When you say a 281 ci engine requires 528 cfm - What 281? Engine HP is normally measured in lbs of air not CFM when calculating airflow to HP requirements. However 28" H2O pressure drop is terrible. RIGHT.
a 3v 281 found in a 05 and up Mustang moves 1800 lbs of air to make 300hp or 480 cfm using your theoretical math. At 528 cfm of air movements or 1980 lbs, the motor would be making 330hp

Either way. The better the TB flow with the least pressure drop across the TB will be better. We can go around and around on the subject - at the end of the day going from the twin 55mm to twin 62mm will result in an increase in airflow and an increase in airflow is an increase in HP - Be it 3hp or 8hp

 

[Dino Dino Bambino]

OK, 528cfm of air is equivalent to 39.6lb of air per minute in a 281ci engine revving at 6500rpm and with a 100% VE.
In reality the VE will be more like 85% so that's 33.7lb of air per minute or 2022lb of air per hour. Assuming a 13:1 WOT air-fuel ratio, that's 156lb/hr of fuel or 19.5lb/hr of fuel per injector (81% duty cycle for stock 24lb injectors).
That 156lb/hr of fuel is good for 346hp at a BSFC of 0.45, and the stock injectors would max out at 427hp (~375rwhp). The stock throttle body would be flowing ~450cfm of air (85% of 528) and require a pressure drop of only 6.2 inH2O to do so.
Upgrading the heads, cams, intake manifold, and throttle body will increase the VE and reduce the BSFC. This allows the engine to ingest a higher volume of air-fuel mixture at any given rpm, and produce more HP per lb of fuel used.

 

[Pentalab]

I just happened to have a large sized (now empty) pepsi from Mc Donalds...with straw. Pinching my nose, I can suck easier than I can blow..... go figure. That was sucking as hard as I could, vs blowing into straw as hard as I could. And yes, the container had been tossed into trash before the..'test'.

Looking at past postings on S197 and other forums, going back to spring of 2011, plane jane 4.6L cars, with minimal mods ( mufflers / tires/ wheels/ K+N filter) going from oem twin 55mm tb... to FRPP twin 62mm TB was a wasted effort. And minimal gains if a PD blower was used....like 3-7 hp.
LT's and hi-flow cats do make a big difference with a twin 55mm tb. Ok, then install the twin 62mm, then it all comes together. The twin 62 tb works.... used in conjunction with other mods. IMO, the twin 62 tb should be towards the bottom of the overall mod list. For folks with NA 4.6 engs, the money spent on a FRPP twin 62mm, is better spent elsewhere.

 

[PonyBoy]

To the experts out there and gratefully piggybacking onto this discussion, I bought a Ford Performance mono-blade TB and a adaptor plate for my 2010 4.6L. Probably a waste of time and money according to what I'm reading, but here is everything being done to the car right now:
High flow cats
X-pipes
BBK ceramic shorties
BBK fuel rails
Performance fuel pump
Ford Performance composite intake manifold
STS Twin turbos
Custom tune

Drivetrain and suspension all upgraded as well.

Opinions? Thoughts? Recommendations?

Thanks,
Ed

 

[PonyBoy]

MAF as well!

 

[Granatelli]

This is getting funny

The guy just wanted to know how to make it TB work. I think we need a new thread

if a 281ci engine is making 281+ hp (over 1hp per cubic inch) its more than 85% efficient

Mono blades make great TOP END power. Everyone says they lag down low . Long story as to why - lets get a new thread - ill explain

 

[Pentalab]

This is getting funny

The guy just wanted to know how to make it TB work. I think we need a new thread

if a 281ci engine is making 281+ hp (over 1hp per cubic inch) its more than 85% efficient

Mono blades make great TOP END power. Everyone says they lag down low . Long story as to why - lets get a new thread - ill explain

Have fun trying to get a mono blade to idle properly. MB's are best suited for the strip.
2011+ cars, in NA format, with LT's, will do 447 rwhp with a manual tranny. That's like 508 crank hp. How eff is that ?

Yeah, start a new thread.... "TB theory explained in detail".... or....." the hidden truth about TB's ". "TB secrets revealed"

 

[Granatelli]

Have fun trying to get a mono blade to idle properly. MB's are best suited for the strip.
2011+ cars, in NA format, with LT's, will do 447 rwhp with a manual tranny. That's like 508 crank hp. How eff is that ?

Yeah, start a new thread.... "TB theory explained in detail".... or....." the hidden truth about TB's ". "TB secrets revealed"

Spot on

Answer - 1.68 hp pr cubic inch

 

[Dino Dino Bambino]

if a 281ci engine is making 281+ hp (over 1hp per cubic inch) its more than 85% efficient

Spot on

Answer - 1.68 hp pr cubic inch

Does that make the modified Coyote 5.0 more than 140% efficient?

The monoblade TB is the best for outright power at WOT but is difficult to modulate at small throttle openings, and that's why many complain of idle and drivability issues. While a tune might alleviate them, many prefer to sacrifice a little HP for better drivability by going with a twin blade unit.

 

[GlassTop09]

Back on topic.......

As far as using the BBK 1763 62mm TB, BBK doesn’t give any instructions to do what I’m about to suggest, but I would also use some white lithium grease specially designed for use on plastic gearing to help prevent gear drag/bind. When I installed my BBK unit I noted a slight drag in gearing when butterflies were moved just off the TPS stop so I got some of this grease & lubed up all the gearing in my BBK unit before final assembly to address this. My 62mm TB has been working smooth as silk since....just over 1 yr of service.

Something else to consider if experiencing a sticking TB.....

Hope this helps