TeamSwift

I didn't know where to post this question but this seems like a good place for it. What's the maximum you can bore out your Maf, throttle body and intake manifold too. On the cylinder head side I'll bore out the runners to match the ports on the head, but I need help with boring out the rest.

_________________
I miss Jomo BRING JOMO BACK


http://sierraclub.com/exxposeexxon

I bored my im out to 60mm, but i look back, and know I should have done it less then that. I lost too much down low to make it worthwhile. It made a huge difference either way.

the stock MAF can be bored out to 48.5mm, possibly to 49mm, but there isn't much material there.

I know Adam/bibbear posted the bore out sizes somewhere on the old forum but I can't find them now

_________________
I miss Jomo BRING JOMO BACK


http://sierraclub.com/exxposeexxon

49 is about max....

_________________
Tony

Proud owner of :

1970 AMC AMX
1989 Suzuki Swift GTi (gone, my baby is gone )
1993 T-Bird

Hey Marcin max bore on the maf is 49mm. You can get one off a 240sx it's 50mm. You just need to cut out a groove for the electronics and maybe tap out one new screw hole (depending on how anal you are about fit. The screws don't quite line up but will work). REAL easy to do. I'm going to take it to a machine shop and see what the max it can be bored to as it is physically bigger than our maf.

_________________
"the Dali Lama told me that on my death bed I would regain total consciousness.....so I've got that going for me"

here's some info from some messages i sent recently, feel free to add pictures/info/corrections ..

like any engine modifications, increased power comes from modifying other parts to make use of the extra air available from a larger tb, things like a larger maf, headers, exhaust, etc...

well the parts of the nissan throttle body that you need to re-machine to make it work are really basic ..
the rod coming out of the nissan tb for the tps needs to have an arm welded/attached to it & the hole in the throttle plate needs to be closed, or you could just replace the plate altogether .. it also looks good to machine off the extra stuff on top of the tb like the coolant pipes.
it's pretty basic, & the 50 & 55mm tb's are quite common @ the wreckers, i've found a few myself already, there are also the fabled 60mm tb's from the sr20 engines. some things to look for when you're going through the wreckers, the tb's that can be modified have the bolts for the tps located vertically, rather then at an angle and they of course only have the one throttle plate.
daleyson has modified a number of them & had them for sale in the past, he's the first source i can think of for these.

i posted a few comparison pictures in the technical album (taken from gticouples website, more available there)

well since the engine runs on both tps & the mass airflow sensor, there's not really any issue once you have the tps adjusted, although it supposedly really helps to have toms chip installed to let you tune the engine properly ..

machining out the intake is actually just a matter of taking a sanding or abrasive bit on a dremel to open it up a bit more, takes only a few minutes, & the bolt patter is identical, no changes there, however you may need longer bolts or studs to mount it.

On the old forum, Jarda mentions needing to use a link AFM to ensure the mixture is not too rich after installing a bigger bore MAF. What is he referring to and what exactly do I need to do?

"I tested the MAF on my turbo setup and it worked OK. However, as with any aftermarket or modified MAF, a link AFM is an absolute must as it will allow you to tune the a/f mixture. Otherwise it will run too rich at idle and run like shit untill you reach 2500 rpm." - Jardamuth from the Buy/Sell post for his 50 mm Hitachi MAF

Has everyone that's bored their MAFs done this?

i doubt hardly anyone has actually done it properly & used a piggyback system.
the bigger you go, the more exaggerated the effect is going to be. one of the things you can, or have to do, is enlarge either the sampling hole, or the escape hole(s), this lets you "tune" the maf to match the stock readings @ a certain rpm, it's the same sort of theory behind jetting a carb.
ray/ssgt92 is a good person to ask, he's been swapping between his stock 45, bored 49, & modified 60mm .. the 60mm definately bogs a lot off the line, probably because it's running so rich.

What models/years Nissans used the 52mm? I'm going to a junkyard later this week and would like to see if I can find one. I have a 98 with the SOHC 1.3 16v and I'm wondering if you think the ECM can handle the increase in air mixture? I have my concerns, but its probably worth a try as it shouldn't be very costly to do. Thanks this is good info you posted here.

i don't think this mod will work on a sohc engine, take a look at your existing throttle body. many of the sohc engines are carburated or use a single tbi unit, the intake is completely different from that of the dohc engine.
i'm no nissan expert, so i just search for them by popping every hood @ the pick-e-part, they're quite easy to spot visually.
daleyson would be the best person to talk to that i can think of.

we didn't do this

yes, but you also take advice from jomo, 'nuff said

HAHAHAHA...so true.

A little education is in order here. The '98 to '01 G13B SOHC engine has a throttle body just like the DOHC G13B does. Have a look at my 2000 G13B 16v SOHC.

Adam is machining me a Nissan 54mm TB for my engine. An adapter plate has to be made to run my stock IAS and the bolt pattern on the Nissan TB will be slightly changed to fit my intake studs, but it will work and it will work well. Note the large smooth tubular runners on the intake.

Later,
Mike

hey very cool, thanks mike !
so '98 was the change-over year ?
anyone have a picture of the earlier ones ?
and before anyone asks, adam=bigbearzuke (our webstore guy)

Yep, Adam the daddy Webstore guru. He is Da Man of TB's and pulleys of course. The earlier '97 and older look just like the TB injection on a 1-liter G10 engine. Those are the pathetic keep 'em for the grocery store visit cars. The new '98-'01 G13B has an awesome tubular intake and 16 valves that are actually larger in diameter than the stock DOHC GT valves. Lots of potential with the new motor even though it is missing a cam.

Mike

fair enough but he did my conversion as well as others without any tps issues he just put it on backwards the arm fits perfectly im just curious

do you have any pictures ? because the nissan tb's use a very different linkage here. i know this first hand & without some sort of proof, this is the same bogus rumour propagating we had to deal w/ jomo for.
or is jomo free again & @ your workplace using your login again ?

i'm sure we can take care of that...

you can clearly see how the nissan TPS arm needs to be modified (modified on left, stock on right), these are also the 2 most common to find nissan tb's in NA, the giant 60mm SR20 TB is exceptionally rare. surface area of the openings vs. stock 50mm is about a 20+% increase over the stock 45mm & the 55 is about 40+% increase, & the volume of airflow goes up exponentially

i have 2 of the 50mm's that i'm sending to daley for modification, he'd be the one to talk to if you want one already done.

*now the images should be viewable*
This is good info. I'm in the process of doing a swap to the 54mm TB, and have a few questions. Hopefully, these images will post (they're in the album here):
[
http://www.teamswift.net/album_page.php?pic_id=680
4. Whats happens to this line? Do you cap one end?
Thanks for any help-
Brett

well, I'm half way into the TB swap. I have a 98 1.3 16V SOHC, and I'm swaping to the 55mm Nissan TB. Ran into a snag last night thought. the stock TB has a sensor on the underside of it. there is a coolant line and an air bypass for the TB there. What is this sensor? there is no where to mod the nissan to work like this. Hopefully someone who has done this can help. maybe there is a way to fake this sensor out, but first I need to know what it is sensing. Also there is a small machined hole in the Nissan's throttle plate, Should this be plugged? I was wondering because the Nissan doesn't have a little bypass around the throttle plate like the stock one has. Thanks for any help you can give-

Hey. I noticed that machined hole in mine too. I'm going to keep the hole in mine, and run the car when the engine is done. If it presents a problem, I'll plug it. Where in the Detroit area are you from? Good to see a local guy on here. We'll have to go cruising sometime.

when u put a bigger tb do u have to bore out the actual intake manifold to make the hole on that physically bigger to make this little coversion work how it should. or do u just bolt the other tb and boom u get more airflow??