hey guys i found a guy who makes custom EFI ITB's so im wondering what size should i get, i plan to get toda b's in the future...

toda headers are like 45mm ID from the engine block, so i was thinking maybe 45mm ITB's sound logical or should i get something bigger 50mm(lose lower end torque?)

i also plan to do a P&P in the future as well

thx in advance guys just looking for some opinion

btw i've searched and most ppl use NON EFI ITB's so maybe the ID size may vary?

 

If you leave the compression alone, 46-48mm would be ideal. If you plan on raising compression to the mid 11' or higher, 50mm would be better.

As for cam size vs ITB size, rule of thumb is always overcam ITB's. ITB's scavange the air so well that large duration, high lift cams can provide a very broad powerband, even with ITB sizes in the mid 40's.

Question though, EFI ITB's in my mind represent fuel injected throttlebodies, aka ITB's. non-EFI ITB's would be non fuel injected throttlebodies, aka carburetors, right?

 

TWM's are better.

 

yeah that's correct i thought that with EFI ITB's it could also be tuned for daily driving when i need it, thx alot for your input!

just another question would anyone know what size's are the holes in the engine block that connect to the intake manifold and headers?

just thinking there is probably not much point getting larger ITB size's ie 50mm if they do not match up with the engine block unless i port and polish, same goes for the headers... or am i totally wrong?

thx again in advance

 

TWN sound good but i live in australia and they may prove to cost more, plus the warranty would be easier to come by if i get the locally made ones.

i got quoted aus$800 - $1000 a pair custom made, and they are EFI

are TWN EFI?

 

doesn't any one know the hole size's of the engine block to the intake manifold and exhaust manifold?

if i had the tools i would unbolt them and measure them myself

thx in advance

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ITSUKA &raquo;</TD></TR><TR><TD CLASS="quote">doesn't any one know the hole size's of the engine block to the intake manifold and exhaust manifold?</TD></TR></TABLE>

The ports on the cylinder head are not circular, so they do not have a consistent diameter like the runners on ITB's, so comparing the size is moot at best.

Your theory is a little crooked. The reason ports and runners taper is to increase velocity. When air travels from big to small, it gains velocity, aka power.

 

oh thx for pointing that out!

call me a noob but i guess i just learnt something!

so how does exhaust outlet work? triangular as well?