As Silver Streak pointed out, there should be no peak horsepower improvement.

Unlike when swapping to a larger carb, swapping to a larger throttlebody only addresses air metering. Without something to address adding more peak fuel you won't get more hp. At most there may (very slim chance) that you'll get a slight increase in fuel if the O2 tells the computer that your running lean and not even that at WOT(closed loop).

Now if some industrious person can crack the table maps then you can do a lot.

 

I would love to see a before and after dyno test on one of these throttle bodies. Many have done it, and many have claimed massive improvements. None have any documentation of any improvements. SOTP is not a reliable indicator of anything less than a 10% gain.

 

Well, To me I think there's a big difference than putting a bigger throttle body on the 300 and one on the 302. I can definatly tell a difference when I get up in the higher RPM's, and I barely have to touch the gas to get it going now.

The throttle body that's on there now can almost fit over the original throttle body...

Isn't the throttle body's for the 5.0's and 5.8's the same? If so, then why in the heck would they put a smaller throttle body on the 4.9's? Wouldn't it be taking in just as much air as a 5.0? To me there's a difference...It's like night and day, but it might not be much of a gain, I dunno. This has really made me want to do more stuff to the ol' 300 for sure.

Matt

 

Thats what I was afraid of, you both have mass air trucks. I was hoping at least one of you had a SD style motor. But considering how easy and cheap I might try it with my '92.

 

No, Mine's SD. My truck was definatly compensating for something when I put the new TB on (Forgot to mention this) When I first put it on, the truck revved up to about 2K and set there for a little bit, and then idled itself right down like normal. I don't know if it was doing something with the fuel, or what, but it was definatly doing something different.

 

Howdy Silverstreak, I didn't see massive gains at all with this mod due to lack of tuning. Without tuning this is a win some lose some mod. Yeah it picks up alot faster on the low end but on the top end it doesn't seem to pull much harder. I'm talking barely. The true test will be when I hook up my truck to a trailer. Hopefully getting matched intake tubes will help it slightly (and my peace of mind) when it comes time to tune this thing. I wouldn't attempt this mod for anything more than the money i put into it. Maybe 20 bucks with TB and cleaning supplies. lol Cheap thrills man. Now if I could tune this thing i'd see some decent gain... but i've already whined enough about that. I wish there were a dyno close to me... is it even possible to dyno one of these trucks? Don't they have to plug into the computer to figure mixture and timing etc? Or are you just talking about getting straight HP TQ from the rear wheels? If I can't get a full synopsis of my engine on the dyno such as timing and mixture at certain RPM's, I won't even waste the money to dyno it hehehe. How much on average does it cost to take a vehicle to a dyno?

Thanks!

Towmanjbo, my truck is not a mass air. I wish it was!

 

I was just talking to a buddy of mine about it (He drag races some) and there's one around me, but it costs about $300 to do so.

I'd like to change mine over to MAF, but it would be such a pain to do...I really don't want to completly redo all my wiring on my truck.

I've been thinking about adding a chip to it, It showed some dyno results on it (like 20 horsepower) but I don't know if it would make more of a difference since I added the bigger throttle body.

The next steps are adding the chip and then a good exhaust, it should wake this truck up just a little bit.

 

i think the overall effect of adding a larger throttle body to a basically stock engine is this...u are seeing more airflow with less pedal effort. so, at 1/4 throttle with the 351 TB it is like 1/2 throttle with the 300TB...the extra airflow isnt measured so i dont see how it can actually gain any power...ur just letting more air in sooner.

now for someone who has done a cam, headers and maybe head work this may be benefical...i may try this for ****s n giggles...

 

The dyno should have a probe that goes in the exhaust that reads the a/f ratio. Ignition timing you are on your own on for the most part. When tuning timing the most important thing to remember is to keep good records. I start with a baseline and see what it puts down. Then I advance it 2 degrees and go again. Then 2 more and again and so on until it doesn't gain anymore. By keeping a record of where it gained and lost power for each increment of advance you will be able to figure out what adjustments need to be made to the timing curve. So far I haven't seen any improvements over the factory curve other than just advancing it 2-4 degrees.

$300 for dyno time is a good old fashioned *** raping. Around here the going rate is $45 for three pulls plus $5 for each additional pull or you can do an hourly rate which I think is $75/hr.

You aren't going to find anywhere near 20hp with a chip. I would be thoroughly surprised if you got 5. Until you've got some significant mods you can find better ways to spend that money.

 

Thanks for the info guys. Optikal, I think you're right about the bigger throttle body making for the easier to get air in quicker. The more I drive it, it does seem like there's not much of a difference...but it seemed like it at first!

The info I got for the chip was from Jet Performance. They have a dyno sheet of a before and after for a 1994 or 93 F150, which is about the same as mine. They show a 21HP gain, but I also noticed they're revving the motor to 5K too, which I don't EVER do.

I thought of this Throttle body like maybe a K&N filter...do you guys believe in gaining 10-15 some odd horsepower out of those? I know I have alot more potential to get more air into the engine, but like you guys were saying, if the motor doesn't need it, it's not going to give you any more power.

Matt

 

If they revved it to 5k rpm it wasn't stock or even close to it.

10-15 hp is a pipe dream for a K&N system.

 

I thought, wrongly I guess, that in '94 Cali trucks were mass air and '95 and newer they all were. Huh, go figure. Not sure where I heard that, oh well.

 

Close, my research shows that in 95 the California (and maybe New York and Mass) 4.9's got MAF/SFI while the rest of the still and SD/MFI. And that was still EEC-IV. In 96 (the last year of our 300/4.9) MAF/SFI went nationwide but in EEC-V's.

 

what no one on here has realized is. you put on bigger tb's your slowing down the velocity also you will need to add a certain % more fuel to compensate for the bigger tb's . thats the only way your going to make anymore power. I also saw mentioned was loose low end torque. you cannot lose torque and gain hp. you either loose both or you gain both they work together you cant have one or the other.

 

Faststang, I totally agree with you on the larger throttlebody reducing intake velocity and requiring more fuel. I removed my K&N FIPK (also needs more fuel to get any power out of it) and put the old throttlebody back on it.

I'm converting my truck all the way back to stock with the exception of the flowmaster 40 I have on it.

Hotrodding EFI 300's just isn't worth it. Maybe when someone comes out with a fully adjustable EFI for these things i'll give it a try. For now carbed 300's are the only way to go for hotrodding.

Oh yeah, and i'm looking forward to my mileage going up from 11 mpg now that the computer isn't freaking out trying to compensate for all the stupid pipe dream mods I did.

Does anyone know a true way to reset the computer and get it back into learning mode? I know with my Jeep Rubicon I have to take off the positive cable and ground it out totally discharging the system then I have to turn the key a certain amount of times back and forth. Anything like this for the Ford?