Stock VE/WM air intake

Also wondering about this as I am trying to keep the stock airbox look of my WM Caprice but up the flow-rate for a dyno tune coming up. I've noticed the VF GTS uses a similar style setup (ignoring the fact it is charged) but I can't see where it draws the air from in the bottom half of the box.

 

just cut the bottom half of the cold air box off... worked on the rice burners..

 

The stock intake location for a CAI is not that bad with a bigger air box and smoother bends, plenty of dragsters in the US in the 10s with a RotoFab, which is not Over the Radiator (OTR), similar to growler, similar to walkinshaw, but apparently better.

 

I'm sure G8 owners and the RotoFab marketing team could explain better, but yeah pipe, velocity stack, massive air box and surface area from what I can tell. The fact that the bulk of the unit doesn't sit over and right in front of the radiator means there is less intake air temperature variance and cooler mean temperature stop / start.

 

You aren't too keen on OTR intakes are you?

I've seen the Rotofab ones online and contacted them - cost was (from memory) about $515AUD delivered, or if I was to buy 10 it would be $313AUD plus delivery- the latter is in case anyone is interested.

Cheers!

 

Haha! Nah my OTR is fine for what it is, just irks me with RON98 sitting in traffic with IATs 70º+ or when ambient is subzero / frosty or when it really pisses down rain, or I drive into a swarm of insects!!

 

Elaborate please sir!

I'm curious as they seem to be polar opposites from manufacturers claimed power gains.

E.g. - Rotofab enclosed air box w/ pod filter - 11rwhp
- Ramjet OTR - 32rwhp

 

Interesting, I might go with the VCM pipe for the time being and see how it goes. If I need to 'update' my airbox config down the track then I will do that next.

 

OK, you asked me to elaborate... No, to clarify, an OTR wins marginally in regard to some criteria in physics, but not overall with regard to thermodynamics and street predicability/risk. OTR has potential for colder air, on-the-move, responding to relatively cool conditions in the first place. Plus having a short and direct tract it has less MAP pressure drop at WOT so is well suited to higher rpm and presumably higher CFM*.
However measuring the effectiveness of anything when screaming its tits off under controlled conditions is hardly the best practical yardstick when 99.9% of the time you use less than 30% of the engine's horsepower (HP=TORQUE X RPM / 5252). Any power gains near max rpm is an entirely impractical and quite useless pursuit – an overly stressed, academic point of contention in a street car, especially with gains of less than 20rwhp – is just MANG, doesn't really matter!

What matters is how reliably your car delivers usable torque at much lower rpm without fuss, as the VE/VF weighs best part of two tonnes, so it's mainly torque (and power say 4000 - 5300 rpm) is what makes country roads and highway on-ramps fun without wringing its neck. What the dyno 'puter says the power calculation is, beyond tuning purposes, is immaterial and typically erroneous. EG. my car used to make good horsepower at high RPM. Now makes 10% less power but is a second quicker 0-100kph. All that's to say that although an OTR is good for slightly more power at ridiculously high RPM you can't feel it or hardly use it. The trade-off is as the above post - greater exposure to the elements and greater IAT variance in your tune. Tuners don't sit for hours on end calibrating optimum performance with IATs wandering 30º-70º-45º, no.

Even if IAT on the dyno was typical like 35º-40º the actual output at the wheels would be crap on 98RON, the figure you get on a graph is a guess as to what the torque x rpm / 5252 would be if the conditions were totally different (Detroit), like at 15º and zero humidity. So while the calculated result looks good on paper, practically the car is a gutless dog at wandering / high IATs. That's where predictability of factors such as IAT, Mass, humidity, turbulence, etc., come into play with a more controlled induction tract like alternatives using the original location. Also less exposure to risk through less exposure to the elements.

Greater predictability and validity comes with flex fuel, as IAT vs knock is not affected much below 130º. For practical, reliable performance up to 50% ethanol will deliver more repeatable actual performance on the street in areas that count (not a graph on a piece of paper) predominantly from greater torque at lower RPM. Similarly an upgraded CAI in the original location would reduce traditional tuning sensitivity on 98RON and add to actual overall performance predictability.

*Complete system intake flow @ 28 inches for an L77 with bolt-ons (255rwkw) is 202 CFM, which is to underline that in practical performance terms there are more significant considerations and challenges than measured air flow (CFM) through a huge plastic trumpet before the throttle body.

 

PIR4TE all I can say is thankyou thankyou thankyou, if even 30% of the posts on this forum were as good as yours the flow of information would be huge. You have absolutely confirmed what I was hoping to read!

 

Thanks for the detail! It makes sense, and particularly considering my driving is mainly is the 1800-2800RPM range, I don't think I would really benefit from an OTR. Looks like Rotofab is the way to go!

 

So do they fit aussie VEs/VF
Besides the US can you buy them here?

 

Here yous go.

 

Cheers PIR4TE

 

Bugger they don`t import V6 ones

 

Group Buy

Looking into group buy, compatibility, shipping specs, MAF and velocity stack options etc. Waiting on some info today and will whip up a form for expressions of interest shortly.