Cold air intake

[Bibs 11,380]

The TLF discount is being set up as soon as they are back in stock

[mdavies 76]

JAWS, As you have the Sports silencer I used your question as an excuse for a run out. Thanks! And I've made some notes.

Made steady speed runs at 2,000, 2,500 and 3,000 rpm in top gear on flat road/airfield. Ground speeds were correspondingly 55, 69 and 82 mph.

Windows closed but opening made no practical difference as the wind noise increased far more than that of the engine. Sport on/off made no difference and not expected to - it would have been very interesting if it had. (Though with the standard intake the airflow paths do differ with Sport on/off. Note that the Sport effect remains very pronounced with the CAI/Sport silencer though.)

When seeking them it’s not easy to find flat driving surfaces - around me anyway - but gentle inclines made no significant difference.

Finding 1: Provided the throttle and the speed were held steady, in comparison to the tyre and wind noises the engine sound was barely discernable at all rpm between 2K and 3K and not significantly different from that at 1.5K rpm.

Finding 2: In the test speed range, the engine sound is very predominantly affected - and becomes significantly discernable - by throttle increases for any acceleration from a steady speed. That applies over the whole test range.

And practical driving on most roads is not done at steady speeds and throttle openings. Switching from artificial steadyness to normal relaxed driving holding “about” the test speeds brings the engine sound up to being perceptible - equally it disappears entirely on downward inclines.

Now to subjective words! For the test speed range and for “gentle/casual” accelerations and “normal cruising” extra throttle demands, even when the engine sound rose to clearly perceptible above the background, it was not at all of the “CAI sound track in operation” sort. That comes into play on overtaking, for instance, and at “medium” power it is distinctly evident. (I’ve previously mentioned it being a “deeper serious sports car sound” - and at high power it is truly loud.) But in normal driving, cruising along with the ordinary traffic at up to 70 or so, with only gentle speed changes, the CAI sound effect is only a “cleaner” sort of sound. (That’s from my previous posted comments - I can’t actually remember what the ordinary intake sounded like!) And it’s not anything I would describe as a drone. And I find it unobtrusive and entirely acceptible. And if you are thinking of roads predominantly flat, straight and at pretty steady speeds up to 70ish, I really don't think you need worry - but, it's not limo-quiet. And all IMO!

Edited April 1, 2012 by mdavies

[JAWS 423]

Thank you for your findings, much appreciated.

[Justin182 11]

Yeah thanks for that

[Al. 294]

Go on Justin, you know you want one! Then I can listen to it and decide also. I'll let you listen to mine, if you will let me listen to yours!! Mine - after the de-cat kit fitted

[Justin182 11]

Al, was thinking about seeing if the Scottish Guys fancy a Group Buy? See what Radium will do us for say 5 kits?

I'm booked up for a decat aswell

[Khyber73 7]

I might be up for a group buy:-) I'm in Aberdeen:-)

Depends on the discount:-)

I'm booked in for a decat too:-)

[Justin182 11]

Khyber, where about it Aberdeen are you? Still not seen another Evora around!

[Khyber73 7]

I'm down by the beach:-) old city hospital. How about urself?

[Justin182 11]

Ah, my mate lives in Bannermill. I'm just South of Aberdeen nearer Stonehaven

[Khyber73 7]

Good stuff:-) so we going to do a radium cai group buy?:-)

[Justin182 11]

I can try doing it whenever, we just need to get some names together

[koorby 2]

IMHO Lotus should make the Radium CAI a factory installed part for the NA car, it's that essential.

I have the CAI and the Sports Silencer fitted and there is zero difference in ambient cruising noise below 3000rpm versus stock

[mdavies 76]

IMHO Lotus should make the Radium CAI a factory installed part for the NA car, it's that essential.

I have the CAI and the Sports Silencer fitted and there is zero difference in ambient cruising noise below 3000rpm versus stock

John, glad to hear that from someone else too! It's good not to be a sole voice - about both your points! Though I can see that for the CAI, approved dealer fit with some conditions might be more practicable than OEM. A suggestion I've made many times on this and other threads. And with the Sports silencer, IMO people would be queuing for them! (Well, those that want a sports car rather than a GT, anyway.)

[mdavies 76]

Sucking Hot and Cold

A few more comments adding to my previous posts about the CAI performance (November ‘11) and related engine bay and air intake temperatures (“Cool or What”, January ‘12).

I’ve speculated that the surprisingly large CAI performance improvement comes from three separate beneficial effects: less restriction to airflow, the pumping effect of the resonance of the tuned inlet pipe length and the provison of cooler intake air. (A clue on that in the name, I suppose!)

I’m now prompted by a 5th March post on Lotus Talk reporting a dynamometer test of the CAI giving a measured gain of +13 bhp on an otherwise standard NA Evora. That is in contrast to the +21.5 bhp stated by Radium that roughly corresponds to the actual road performance gain I measured. Radium and the +13 bhp test car had different exhausts - and probably much else. It is possible that a free-flowing exhaust is important to getting more from the CAI but I’m not aware of anything that has been investigated about that. This is about other things.

One thing I’m noting is that the GTN Motorsport brochure lists the Engine Louvre plastic cover (replaces the standard rear glass) as for: “...weight saving and improved heat dissipation from the engine bay”. And I’m coupling that with hearing from a project to increase the power of the NA Evora (not Radium related) the comment that: “Just getting the engine bay cool gave 5 bhp.”

I’m interested particularly in whether that +13bhp dyno test effectively provided for a key aspect of the CAI operation - getting near to ambient temperature air to the CAI intake filter area. (I assume Radium had this well managed!) Presumably the usual big fan was positioned at the front of the car, but that alone is unlikely to replicate the airflow through the inlet grill to the CAI that would be given by a moving car, including the assistance given by the other grills and the body shape perhaps drawing in air. But whatever was or wasn’t done, the following may be relevant - and I found it interesting anyway!

My Cool or What? measurements found that the CAI accessed air at only a very few degrees above ambient when the engine bay temperature at the end nearest the CAI was around 27 C at medium cruising speeds and with more power, rose to 35 C. Also, with the car stationary and the hot engine turned off, the temperature at the CAI intake point behind its screen rose towards the engine bay temperature over a few minutes. (Details in the C or W post.) For an engine running at power on a dyno with the car stationary, that effect would be likely to be greater.

I understand that engine power varies with the square root of the Absolute air temperature. (As well as pressure, humidity etc. and formal measurements are converted to standardised values. ) For example, comparing an ambient of 15C at the CAI intake with an engine bay temperature of 30C, both typical of what I measured for a moving car, gives a power reduction at 30C to 97.5% of the 15C level. 276bhp would reduce to 269bhp. That 7 bhp is probably a greater temperature differential than applies in normal operation between a standard and CAI Evora because the standard inlet picks up near one end of the engine bay. However Radium went to the trouble of a screen and named their device a “CAI” - presumably after some research! And above I’ve noted the “5bhp from a cool engine bay” statement.

PS1: Bearing in mind all the uncertainties I’ve mentioned: 13+7=20. (Proves nothing - I just mention it!)

PS2: Re the engine grill, I recently enquired of Lotus whether it could be sold separately, e.g to those already having the Sport exhaust. I was told it is priced at 395 + VAT and very likely could be. The next day I was informed that fitting it involved cutting out the window glass and bonding in the grill - so that’s a no for me anyway!

Edited April 9, 2012 by mdavies

[Bibs 11,380]

http://www.thelotusforums.com/forums/topic/50371-sale-lotus-evora-cold-air-intake-from-radium-engineering

Discount details for full forum members, thanks Radium

[Myfavedave 2]

Hi Bibs, that link doesn't work for me..

[Bibs 11,380]

You need to be a full forum member to access the discounts section.

[Myfavedave 2]

I see.. how much is the discount?

[Bibs 11,380]

8%.

Think not what the forum can do you for...

[Myfavedave 2]

[RJB 114]

Arrived, fitted, tested, Wow! What a great upgrade but be warned, the sound under hard acceleration from 3000rpm is dangerously addictive!

[Bibs 11,380]

Did you get the FFM discount?

[RJB 114]

Sadly no - I ordered back in February but they were out of stock. Still well worth the moderate expense and curious how large (and heavy?) the stock intake system is.

Edited April 18, 2012 by RJB

[mdavies 76]

Arrived, fitted, tested, Wow! What a great upgrade but be warned, the sound under hard acceleration from 3000rpm is dangerously addictive!

Great isn't it! But a key question: which exhaust do you have? Sure I'm not the only one awaiting a report from somebody with a standard exhaust.