I have bought a plenum off of ChrisP (monkey boy) and plan to finish off polishing it.

 

Now I seem to remember (was it Duffer?) mentioning a TB mod? Can anyone shed somelight on this for me?

I think its the following.

 

The throttle bodies of the Z31 300ZX are larger letting in more air. You replace the stock Z32 ones for Z31 ones.

it could be this http://www.300zxclub.com/showthread.php?s=&threadid=8377

 

I think there is something else to do with modifying the butterfly or something like that ...

 

Read it somewhere

Excellent link there thanks chrisP :bow:

 

Now unless anyone can post up as to why not to do this then I will be modding asap :smash:

Excellent link there thanks chrisP :bow:

 

Now unless anyone can post up as to why not to do this then I will be modding asap :smash:

 

Same here....can anyone convince us why not to do this :D

 

Quality video btw :rofl:

I have pm'd the chapie that posted it as he was online so we'll see if he has any more info/advice since that was posted as it was put up in 2003.

 

just thought id let you know so everyone dont do the same and pee him off :)

 

This looks like a must....roll on the weekend :dance:

Oh that mod?

 

Some Plenums have a screw where the butterflies are stopped. YOu can screw it down to make the butterflies open a little more. Ones that dont have the screw you have to grind away some of the stopper which is preventing it from openeing all the way.

 

Its acutally dubious whether it makes any difference. I had the scew on mine and I dont think it actually did anything to the performance of the car

There is a long discussion about this somewhere......... I will try and find it.

Here - http://www.300zx.co.uk/forums/showthread.php?t=18846&highlight=butterfly

and here - http://www.300zx.co.uk/forums/showthread.php?t=30108&highlight=butterfly

Heheheh, and pictures posted by me. LOL

 

I remember that :D

Right, I've just done the mod. Mine had the big metal stop, instead of the screw. So those with the screw can just adjust it(or remove screw). Those with the metal stop can just bend the tap out of the way of the metal stop. See pic.

 

 

With the aid of my Datascan tool, I noted the before and after reading for the TPS at Full throttle.

 

Before : 4.16v

After : 4.5v

 

I have'nt driven the car yet to tell it if makes any difference to performance.

let us know m8

 

sounds a interesting mod

 

cheap too :)

 

Before : 4.16v

After : 4.5v

.

 

Cool, I did the mod to mine but did a load of other stuff at the same time (chip, boost jets lol), I hadn't seen anyone post a quantified improvement but I guess there it is :)

 

I had the screw iirc, would've been good to adjust it on the rollers and compare the curves.

Right, I've just done the mod. Mine had the big metal stop, instead of the screw. So those with the screw can just adjust it(or remove screw). Those with the metal stop can just bend the tap out of the way of the metal stop. See pic.

 

With the aid of my Datascan tool, I noted the before and after reading for the TPS at Full throttle.

 

Before : 4.16v

After : 4.5v

 

I have'nt driven the car yet to tell it if makes any difference to performance.

 

I have done mine now...

 

Readings on TPS via ConZult :-

 

Before : 4.00v

 

After : 4.36v

 

I took my pipes of and checked the butterflies were opening 100%.

I had to take the bolt and nut off to get the completely open position and the throttle bodys stopped them opening any further.

 

TBH I havnt noticed any difference but then you wont unless you get it on a rolling road as mentioned above.

 

the TwinTurbo.net site have posts on there mentioning that the standard slight angle on the butterflies is set like that as it works better for air flow on standard/stock motors.

 

But i think opening them right up should help in some microscopic way to improve flow on my modded Z due to the increased air flow with the filter and exhaust system.

 

As for the throttle body bore mod where you put the Z31 bodies on....well...this post:-

http://www.twinturbo.net/net/viewmsg.aspx?forum=technical&msg_id=923328&words=butterfly

would suggest that that dont work as they dont fit...Hmmmm..interesting.

 

The only way would be to bore the origionals and fit a larger butterfly.

 

Any more info on any of this anyone? :)

 

CheerZ :duffer:

What about knife-edging the leading (and trailing?) edges of the butterfly?

 

I've got an S13 TB I've done this to, unfitted.

oh...and by the way...

 

exactly how does the TPS alter/effect the settings/running of the car?

This made interesting reading:-

http://www.twinturbo.net/net/viewmsg.aspx?forum=general&msg_id=1244744

They talk about DYNO runs and show a chart.

Its all quite contradictory though as some say theres a loss due to over angle of the butterflies(obviously dont over angle them then....DOH) and others say its better with more air volume intake.

The DYNO charts show slight variation on runs but yet again some peeps say HP will vary inbetween runs anyway and a 6hp flucuation is not unusual and others say it wont.

I think it depends alot on the ambient temperature and air pressure/density.

Some unmodded Zeds who have done DYNO's claim to have more power than others with slight mods.

There Fuel is probably a major factor in this too

 

If you read all the other posts/links below the message it makes very interesting reading.

Bits about the TPS...contradicting results on this too.

digging up an old thread. what are the opinions now on this? good or not worth the hassle?

digging up an old thread. what are the opinions now on this? good or not worth the hassle?

 

No. I've discussed this in more recent posts.

 

The reason became obvious after closer inspection - Basically the throttle valve is deliberately set at this angle because its the same angle as the intake pipes enters the throttle bodies, and therefore the intake air.

 

Changing its angle so the valve is horizontal would actually restrict flow.

I did this mod, then after legrath's advice, which i holy trust and makes sense, i put it back to normal....