alrite i did some research and i couldnt find much info bout this. i jus get info about type r motors that have them 98spec and up and 96-97 have the 4.4.... i hear 2 stories out there that the 1 to 3 gears are basically the same but the 4th and 5th or diff.... then i hear other story sayin that they are really diff like nite and day...and some pople say theres no diff at all...well i have a jdm gsr with a 96-97 type r tranny 4.4 fd and lsd with basic bolts ons and intake mani..i wanna keep this all motor.... no boost in the future...prolly jus some interanl work.... i wanna switch the fd to 4.78 for better 1/4 mile times and acelleration... u think its worth it or should i jus keep the 4.4fd... i dont drive on the freeways as much so it wont matter bout that... if so id get the 5th gear of a gsr for 97.21 from acura dealership to put on it if i hated the rpms on the freeway.... well i was thinkin bout gettin the type r fd from hmo for 410 shipped....well if anyone got any input on this or has done a jdm gsr w 4.78 fd please let me kno pros and cons would be sweet

 

You can use the 4.7 and since your in there swap to the ls 5th for gas mileage or switch to the gsr 5th instead of the itr 5th. Will give you a better cruising gear for the highway with the ls but if you did the gsr 5th you gain some beter mpg on the highway without 5th being to short.

But its your call.

 

Lower RPM does not mean better economy.

JDM 98+ ITR uses a 4.785 FD with GSR 4/5 gears. Pre 98 JDM ITR uses the same ratios as the B18C5/B16A2.

Depends on your plans for the engine, if you are going to keep it bolt on or even cam'd 1.8 then a 4.785 or 4.928 FD will work well depending on your tire size and RPM. If you are going to build it or go 1.9-2.0, then I would go with a close gear set.

 

my plans is N/A and jus cammed.. nothin to big or serious... my tire size is 205/50/15


are you sure the 4.785 has gsr 4th and 5th gears???

 

What is your fuel cut set at?

Yes, I'm sure.

 

8400.... are u sure cuz in my buddy gsr at 80mph he sittin at 4k on the freeway.. and my buddy got a 98spec 4.7 fd on his b16 and at 80mph he at 5k?

 

Different tire sizes or speedometer is off. B16 5th and 4.7 is not 5k at 80 on common 23's.

 

hmmmm i seen on some threads that with this tranny on diff motors they still sit at 5k in 5th at 80? the fd should change that so i kinda belive it

 

Engine doesn't matter. Gear ratio, final drive ratio, and tire size dictate the RPM for any given speed.

 

so should i jus leave mine how it is then and not get the 4.7 fd?

 

i compared the 96-97 typer r 4.4 fd to the 98spec 4.78 fd and i put the tires the same and everythin annd the mph is diff..... so was i rite... i should sit at 5k at 80 with the 4.78 fd.. cuz rite now wit the 4.4 fd i sit at 4k at 80




http://www.fatboyraceworks.com/gears...raph&Compare=1

 

B16 5th, 4.785 FD, and 23's = 4,700 RPM at 80mph.

 

close to 5k lol

 

Do you mean its not the ONLY thing in better fuel economy?

 

troof

 

No. Higher RPM should net you better economy if you keep your foot out of it.

 

explain, bc at higher rpm's your engine is obviously working harder thus burning more fuel

 

im confused too lol

 

for real, but i love to learn though

 

Well i think what he's trying to say is higher rpm up till a certain point where you're just barely touching the throttle to keep the car cruising (obviously you can't be barely touching the throttle to keep the car crusing at 6000rpm)

At that point you're not burning much fuel but you're going much faster, thus more mileage for the same amount of fuel.

Don't know if i make sense but i do get better mileage driving at 3500rpm on the freeways compared to 3000rpm haha so i was figuring out too

 

think about load on the motor also

 

Correct. Lower gearing means less throttle needed to keep the car moving. Less throttle means less fuel, means higher economy.

 

i agree, but i beleive in lower gear your ecu still makes more gas available, just like if you use cruise control you use less gas, because your ecu isnt expecting the chances of you flooring it, so i think it still oversprays in lower gear

 

The ECU calculated fuel based off load. Its dictated by the MAP sensor (load). Less load at higher rpm to cruise then there is at lower rpm to cruise. Plain and simple.