Jim Hill at ProFlow Design has bored out my 92 SE throttle body. It's nowq 2mm larger, tapered, new butterfly and shaft, and matches up with the plenum intake. When I took it off there was a 1/16" (2mm?) black ring around the TB face that distinctly defined how much smaller the TB was. I used these guys for my Honda S2000 and there was a noticable difference on throttle response. I install it in the Max this Tues (31st). I'm a jerk I originally wrote the 24th.

SEE PICS further down.

Price was $160. including shipping back Priority Mail. I sent it in FedEx.

If you're interested contact Jim at proflowdesign@hotmail.com

web site is, http://www.proflowdesign.com/

 

performance-wise of course.

I am thinking about doing this soon, but am trying to research it a bit more. how many mm is the TB stock?

 

The stock TB is 62mm and mine is bored out to 64mm. More air generally means more power. I know you will have sharper throttle response. If you have a cold air intake, then that would match very well with this TB.

 

I have a spare TB, intake plenum and manifold so I decided to bore out the TB. I sent my spare TB completely disassembled, plate and shaft removed to ASP Racing. They bored out as much as, shipped my TB back with a new throttle plate then I re-assembled it. It cost me about $125. I have yet to install the TB because I'm trying to decide what I'm going to do with my plenum and manifold. (port match/polish, extrude hone, etc) The new plates measured 3/16" larger than the original, not too sure what that equals in mm. Check my homepage for under engine mods for pics.

 

I've done Extrude Hone on another car. I would port and polish if I did it again (and also do the cylinder heads). Extrudehoning simply reams out the existing passage as it smooths and polishes, whereas porting straightens and/or carves out walls to maximize air flow. It might come down to your budget - do what you can afford.

I would, however, Extrudehone an exhaust manifold, but not the Max's. It's too short and stubby from a cost/performance point of view IMO.

 

When ever Extrude Hone "usually" mentioned on this board there's a negative post about it, due to some of the SC 4th gen guys who have done it will little to no HP gains. I thought Ext Hne enlarged the passages along with smoothing it. I'm kinda concern with the plenum deep contours, whereas the puddy from the Ext Hne process will get deep inside. What other car did you do the process on? I realize that good flow lies within the head also, but at this point I'm only into bolt-on can't have any down-time. Besides all these mods I'm doing will help on my next project, 510 with a VG30E (when ever that begins) Would you happen to know of a web-site with complete detail on port/polishing and possible a porting kit. I know there's a process to porting/polishing, but I'm strickly a DIY's. Ones budget usually constitute their available mods, how true. Another member tried hand porting the 4th gen exh manifold and he gained about 1-2 hp. Which leaves me to wonder how efficient the OEM intake and exhaust system is with our Maximas, gotta be pretty efficient form the factory. MIKE

 

Porting and polishing is not a DIY job, it's more of a "science" performed by an experienced speed shop with a flow bench (to check how well they are doing). The ExHone job will cost about $550 and yes, it will get into the crannies. I suppose it depends on how bad the original casting turned out.

I did it on a Honda S2000. I bought a spare intake and sent it out. Taking off the stock was a ***** and it turned out to look pretty good inside. I learned that this engine is not the highest output per liter for nothing! 120 HP per liter.

 

I've called a few shops around the area lately because I'm going to be buting a used engine and doing a "mild" rebuild on it.. port/polish the heads, and bore out the intake manifold a bit also. TB will probably go with it too, but I don't know if $125 is worth it just for the TB. possibly with the rest of the flow-work that I'm doing it'll make a difference.
62 to 64mm is about 10% more area, which is quite a bit to be opening up- so that SHOULD mean more power.

As for costs on port/polish, most shops around here do a "street port" starting at around $250 (more aggressive at $400 and up), plus you'll have to have a valve job for about $140.

so for $400-750, you can have a set of rebuilt heads that should flow pretty damn good.

 

instead of porting the TB why not just swap it out with a 240sx 89ka24e soch engine TB, it bigger than the max and it A popular conversions for the z31

 

I'm game for at least trying it...

which years, tranny options should I look at?
Obviously I'll need one with cruise, but what about pre 9/88/ post 9/88 and auto/manual?

there's 4 different ones listed with cruise for that particular year.

thanks.

 

Matt...we're talking TBs here.

Anyway, this is one beautiful mod. Great punch from 3500-5500 rpms. Passing is a joy. I can't wait to see what my Y pipe will add!

BEFORE

They bored out the black ring.




AFTER

 

Here are my before and after pics

BEFORE




AFTER

 

[QUOTE]Originally posted by Matt93SE
I'm game for at least trying it...

which years, tranny options should I look at?
Obviously I'll need one with cruise, but what about pre 9/88/ post 9/88 and auto/manual?

there's 4 different ones listed with cruise for that particular year.

thanks. [/QUOTE

matt you would have to stick with 89-90 with cruise, here is a little right up for ya:
The throttle body(ies) on any car is how the amount of air entering the engine is controlled. Simply a tube with a butterfly valve in the center that rotates to adjust the flow rate of air into your engine. Throttle bodies take their name from the thermodynamic principle that they work on.... you guessed it, the throttling process. A throttling process is defined as the flow of a fluid through a relatively high restriction into a region of lower pressure with enthalpy remaining constant throughout the process. By replacing your throttle body with one that has a greater flow rate, one of the most restrictive parts of your intake system can be removed. Gude sells a modified Nissan throttle body for a few hundred dollars, or you can go the Nissan route with a throttle body from an 89-90 240sx ka24e sohc engine with cruise control. At a local junkyard, expect this to cost anywhere from a few dollars up to $100. The going rate here is $50 even. If you got the above throttle body, it is a direct bolt in installation. If not you will have to modify something to make it work. Note that the diameter of the intake manifold(collecter as some prefer to call it, the uper 1/2 of the manifold) is slightly smaller than the mating surface on the 240sx throttle body. You should port the manifold to match the throttle body. Simply finger tighten the throttle body onto the manifold and scribe a circle matching the outlet of the throttle body onto the manifold. Remove the throttle body and gring away at the manifold until you have removed enough material so that the mating surfaces of the throttle body and manifold match. Grind about 2-3 inches into the manifold, gradually reducing the amount of material removed so that the transition is nice and smooth. Make sure you stuffed a rag into the manifold to prevent metal shavings from falling into the engine if you did this with the manifold installed! DOH!



--------------------------------------------------------------------------------

 

Candiman

(Is your name Sammy Davis Jr?);-)

Was your original tapered? It looks like it wasn't kept on the rebore. This might explain the higher cost of mine vs. yours.

 

Candiman

(Is your name Sammy Davis Jr?);-)

Was your original tapered? It looks like it wasn't kept on the rebore. This might explain the higher cost of mine vs. yours.

 

Yes, I know that. there was another post above that suggested using a throttle body from an 89-90 240SX. I check the salvage yard, and there are SIX throttle bodies for the 89 alone, depending on transmission options.
this MIGHT be a considerably cheaper if I can find a 240SX TB for cheaper than I can have the OEM one bored out.


The other stuff I was talking about was basically to improve breathing in general. there was mention of that earlier in the post too, and I got a little carried away by that.

 

I couldn't get these shots on my earlier post.

BEFORE



AFTER
Notice they can only bore to the small pin

 

Just ordered a 240SX TB. $48 after shipping. I'll see what happens when I install it next weekend.

 

Wait, the 240sx TB is bigger than the Maxima?

 

But I'm sure you did a little research before hand, which 240 TB did you order? (eng/trans/cruise/etc) And I have to agee with Jeff on this one, hard to believe the 2.40L TB larger than the 3.0L V6, but I guess those engineers figured out the engines volumetric efficiency. Then again the Ford 5.0L TB not much bigger than the Max

 

Turns out someone was giving poor information above...
the 240SX TB is larger than the Z31 and 2nd gen Maxima TB, but NOT larger than the VE's TB.
the only one larger than the VEs is the Q45 TB, which is 67mm if I remember correctly.

these #s are from Nismo87se, who's studied this stuff considerably.
so obviously I just made a $50 mistake. oh well. **** happens. possibly I can hawk it off to a junkyard or a 240 owner or something.

 

know the dimensions of the 89-94 VG TB, since its a dual inlet how much could each be bored out?? I know the LT1/TPI guys have aftermarket units bored to 52mm and 58mm, any chances of doing this to a TB off a VG Maxima??(although I'm sure it proably is possible, any insight)

 

Sure, it's possible. Kaleb and I have both done it on our VGs. a few others I know have tried it. it's good for a few HP.

 

Duh! I thought I was going crazy.

 

All you have to do is post on the www.z31.com board that you have a 240sx TB for sale. There seems to be a shortage of the TB's according to the members. This would be a nice way to get your money back or make alittle more .

 

Thanks bud. I'll do that whenever I get it in the mail and clean it up a little.