8 Throttle Body Intake

[Damien]

The whole thing needs tweaking : )

Can't do any tuning until I work out why the ECU is spitting the dummy.

 

[lowboost]

What kind of wheel hp can you make with ITB's?

 

[Damien]

When I get mine completed and on the dyno I'll let everyone know. I have a "before" dyno sheet so we will be able to compare the differences.

 

[Damien]

I should point out that the main reason why I'm converting to ITB's is for a sharper throttle response. I'm not expecting much increase in peak power but it will help when I fit cams.

 

[ed_ma61]

What kind of wheel hp can you make with ITB's?

itbs are definitely not a peak HP thing

the road is not a dyno - its about 'driving'

 

[rivmasta]

So ITB's improve torque, not necc HP?

 

[Pro]

they will improve outright power compared to a single TB - but you need cams to make the most of them. they will improve airflow - but so much so that the stock cams won't keep up.

so it's like saying icecream (ITBs) is better than a chocolate bar (single TB) (let's just say it is, okay?). but you need a cone (cams) to eat the icecream, don't you?

that said, they will improve your average power and torque by a "noticable" amount.

 

[rivmasta]

sooo... if I have my 4 cones with 232 duration @ .050" and 9.8mm lift I'd be taking good advantage of my iceream scoops?

but to start with we'll still either use two stock chocolate bars, or one 100mm chocolate bar.

 

[ed_ma61]

i wholly disagree.

runner mounted ITBs will not produce greater peak HP than a properly sized plenum mounted single. perhaps comparing itbs to some stock single, yes, but if youre chasing big HP at WOT such as dyno comps (queens) or drag racing, a big single is the way to go

 

[rivmasta]

but for a racecar, where you're after torque as well as HP??? not for a dyno shootout...

 

[Damien]

An advantage of ITB's is that with different length trumpets (assuming you have room) you can tune where in the RPM range the pressure waves are most effective. For a circuit race car you'd probably want that to occur at peak power but for a rally car or road car where you're using a larger RPM range you'd probably want to tune the pressure waves to arrive at peak torque.

 

[rivmasta]

Offroad buggy - all the room I want..

pk tq looks like the go.

Anyone have the dimentions for the rb26 (or is it rb30) ITB's?

 

[ed_ma61]

what would you specifically like me to measure??

 

[rivmasta]

what would you specifically like me to measure??

Cheers ed - ID and any taper, length from end to end not inc any stock trumpets. Thanks.

 

[ed_ma61]

mate,

theres zero taper on the bore, the whole assembly is only 34mm thick

butterflies are 45mm on 90mm centres

overall outside dimensions are about 190mm x 78mm x 34mm

these dimensions include the spring return and linkages mounted on the ends of the alloy body.

see pic earlier in thread

 

[ed_ma61]

Finally got the chance to do a bit of fabrication and assembly work on the manifold plate, throttle bodies and linkages today:

 

[ed_ma61]

QUICKTIME VIDEOS of linkage function 400kb each

note the bloody perfect (!) linkage ratio between the 2 banks...

http://www.v-eight.com/images/Images_Forum/Manifold_Plate/MOV00001.MOV
http://www.v-eight.com/images/Images_Forum/Manifold_Plate/MOV00002.MOV
http://www.v-eight.com/images/Images_Forum/Manifold_Plate/MOV00003.MOV

cheers
ed

 

[Zuffen]

ed,

You would have to be pretty happy with that.

Excellent work.

 

[mycarhasposessedme]

Awesome incredible work.
Top stuff ed.

 

[Damien]

Ed, will you be using stock cams or something a bit more aggressive? I'm having difficulty with sealing against the huge vacuum produced by the stock cams which is resulting in a high idle speed.