Throttle body selection

Gary57 · Post by **Gary57** » Sat Jan 26, 2008 3:23 pm

So this spare CA18DET I have doesn't have a throttle body.

On this motor I am looking for lots of low down toque and very fast throttle response, from idle I want to rev fast and smooth kinda like a bike or race motor.

I have been looking at a throttle body for the motor but am not sure which to go for. Do I try fit the stock one back or do I try get something bigger. Will going bigger effect the low speed cylinder filling, bigger bore slower speeds?? What is the size of the stock TB?? Are those universal 70mm throttle bodies any good??

I know individual throttle bodies would be answer but this head is 8 port so that is out of the question, well unless someone wants to swap for a 4 port

.

Phinx I know you have done your throttle body so please post you findings.

Gary57 · Post by **Gary57** » Mon Jan 28, 2008 2:15 pm

So no one has any ifo on fitting a bigger TB and what effects it would have??

Phinx · Post by **Phinx** » Mon Jan 28, 2008 4:51 pm

SR20 60mm ported TB
---------------------------

The car jerks at low throttle positions when cold. Will only get worse as the size increases

Small increase on high end revving, Throttle becomes very sensitive

It is a real mission to get the TPS hooked up correctly on the low port SR20 TB..

P.S - Stock 54mm

veecee · Post by **veecee** » Mon Jan 28, 2008 5:18 pm

you can do throttle bodies on an 8 port.

you just keep the piece with the butterflys. on one side its 4 port and on the other side its 8 port. so its like an adapter built for you by nissan!

then you just need something that will allow you to put throttles on!

also bike throttle bodies are a freely available and common upgrade. the suzuki gsxr has 4X45mm throttles. very nice. and they're mounted with rubber couplings. hmmm... makes life easier too.

Gary57 · Post by **Gary57** » Tue Jan 29, 2008 8:31 am

So it is a bugger to drive with in traffic??

VC I think I am looking for a 4 port again.

veecee · Post by **veecee** » Tue Jan 29, 2008 7:55 pm

listen to me...

there is nothing wrong with an 8 port motor!

its like saying the murcielago is no good because it has 30 odd horsepower less than the murcielago superleggerra!

mounting throttles on a 4 port motor would be just as much of a task as mounting them on an 8 port motor!

i think you're splitting hairs (and ports!) for nothing!

Gary57 · Post by **Gary57** » Wed Jan 30, 2008 8:13 am

My problem is the that the 8 port head will flow less at high rpm and boost than the 4 port will:

The area of the 8 ports are smaller than the 4.
There is a greater friction area on the 8 port than the 4 port, with respect to how much it will flow.
8 port with butterflies is great for a laggy turbo, helps it get into boost.

Doctor G · Post by **Doctor G** » Wed Jan 30, 2008 8:43 am

Can you not change the 8 port to be a 4 port by removing the material between the ports?

Gary57 · Post by **Gary57** » Wed Jan 30, 2008 8:45 am

I suppose you could but what I mission.

I will keep the 8 port head, maybe swap someone for a 4 port if they are looking for more low down torque.

Doctor G · Post by **Doctor G** » Wed Jan 30, 2008 9:13 am

Or get 8 x 38mm ITBs in a custom plenum

Gary57 · Post by **Gary57** » Wed Jan 30, 2008 9:16 am

Or get 8 x 38mm ITBs in a custom plenum

Where am I going to get those from??

Gary57 · Post by **Gary57** » Wed Jan 30, 2008 11:46 am

This is beautiful, check this link.

http://forums.nicoclub.com/zerothread/226207

veecee · Post by **veecee** » Wed Jan 30, 2008 8:54 pm

yeah - i've seen that before - it is lekka!!!

but you see the bit that has been left on the engine. the bit that holds the fuel rail??? the bit that the throttles bolt onto??? the bit that would hold the 4 butterflies in the 8 port head???

thats the bit i was talking about!

so if you keep the 8 port head - you're going to lose what... 10 horsepower???

veecee · Post by **veecee** » Wed Jan 30, 2008 8:55 pm

the plug on that first cylinder interests me. it almost looks like my xtrail coil-on-plugs!

Gary57 · Post by **Gary57** » Thu Jan 31, 2008 8:16 am

But the thing is to do all that work to find out I am making less power than I am now?? Is it worth the risk??