Why did Nissan put a huge throttle body on the VH45?

[tmorgan4]

The more research I do about engine performance in general, the more the VH interests me. Nissan obviously spent a lot of time and money designing the engine to very high standards. One thing that I've been curious about lately is why Nissan used such a huge (90mm) throttle body on such a "tame" engine. I constantly see people buying these Q45 throttle bodies to put on high horsepower engines (making much more power than a stock VH) and many of which don't even end up in Nissans. It appears to be a common swap in high power Supras. I know the forced induction on many of these cars comes into play, but it just seems crazy that a 90mm throttle body was used on an engine making 340hp and the guy who welded my oil pan just built a 1400hp engine using a 100mm throttle body.

What's the advantage? People talk of losing drive ability on an engine by going to too big of a TB, yet this is non-existent on the VH.

[gs14racer]

Actually the vh's tapers down to 80mm at the butterfly. Just throwing that out there sorry.

[XJared]

big throttle chambers dont kill drivability if the manifold is designed correctly....

[Carl H]

^ tru.but also consider the size of the engine...an sr spining at 5krpm is not the same as a vh spinning at 5k rpm.like everthing of the era i think nissan wanted to make sure that it would function properly even if it was outside of its 'design limits' for induction...i mean after all if the stock maf can read 400+whp then what else did they do?

[WizardBlack]

^ tru.but also consider the size of the engine...an sr spining at 5krpm is not the same as a vh spinning at 5k rpm.like everthing of the era i think nissan wanted to make sure that it would function properly even if it was outside of its 'design limits' for induction...i mean after all if the stock maf can read 400+whp then what else did they do?

The engine was clearly built for endurance racing from top to bottom, IMHO. I have been taking one apart this last week, read the SAE paper (which doesn't cover half of it), etc. I want to see what one of these will do at 30 psi and 8krpm with built internals. I've no doubt the block and crank will hold whatever you throw at it.

The throttle is designed to allow for an intake size that doesn't require the air tract to taper up excessively as the air flows into the intake manifold.