Intake sounds like an F35!

[fourpot]

Hi all,

I have a 4.6 stroker (Clegg engine kit) which is running well after 20,000 miles. It's in a 1998 XJ, using a 1999 intake manifold and a BBK 62mm throttle body. I have a 'cold air' system with a big K+N on it and just a plain tube to the throttle body. I used the same intake and throttle set-up when the engine was just a stock 4.0.

The intake makes a really really loud sucking sound (like suck air through your teeth really hard). It does this with the filter and tubing on, or the same with just the bare throttle body. Apart from the extra cubes, the only other real difference that might increase intake suck is a stage 1 cam. Everything else is as it was as a 4.0.

Performance is good - both power and economy.

Is this normal for a stroker upgrade, that the engine sucks that much more air in from an extra 600cc? Is it being strangled?