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Cold Air Intake PLUS from TDI

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Me too.

I have been holding off on buying a Radium and following this thread with interest in the hope that a newly developed product will be shortly available. More confusion than enlightenment at the minute though.

I'm sure the dyno day be an interesting day for all of you involved. Be sure to post any revelations and your dyno results for us to scrutinise. And don't let the snow put you off, it'll just provide a more interesting drive there and make for a more fun day overall

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My understanding is the only difference is a larger bolt on filter. The increased size means one has to have a modified plate/cover for the Intake. 7-8bhp improvement. I bought a radium and tdi said they'd sell me the filter for 100 pounds.

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Khyber, great! You have the news that I and many were hoping to hear tomorrow at their test day. (Snowed off for most now it seems, certainly me.) I will give them a call in the morning if they are open, to order mine. Glad too that they have made that part of their work clear. I understood that the shape of the intake mouth inside the filter was also improved, but that may be for the other application that I have been mentioning in guarded terms.

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There are two applications to my understanding

1. For the supercharged engine

2. For the n/a

The market is larger for the supercharged engines as there are no n/a exiges:-( I suspect they'll b focusing on intakes for supercharged evoras/exiges.

On a different note...I wish lotus had done the exige v6 in n/a form for about 40 k:-( i think there would have been a market for it

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What you "suspect" re the S engine, for the new Exige at first, may well be the case, I understand. (That could fit with my previous guarded posts!)

Wouldn't it be interesting if Lotus had something for fitting to the Exiges - perhaps those of a particular type - that could be used on S Evoras, as a retrofit? (Track use only? That's what is marked on the Evora Lotus Sport silencer, supplied and dealer fitted on mine from new.)

As you first posted, TDI have now come out with their offering for the NA. Perhaps they feel it is not their place to speak about a "possibility" for the S.

Just spoken with TDI re the NA item. Confirming Khyber’s post above, TDI can immediately supply a filter for the £100 (+VAT, I guess)

Now I have further information that also explains the “need 50 orders” to make it economic, that I posted earlier. TDI have worked on a) the filter and b) the intake tube. 65-70% of the gains come from the filter and the rest from a new tube to replace Radium's. It is the complete combination for optimum performance that would need the 50 orders.

The special filter incorporates a bell mouth to the intake tube, as I previously mentioned. That is important and stems from TDI's work on previous generations of Japanese cars. It gets a lot of air in through a smallish filter. This has to be jointed on to the Radium tube. (Some sort of strap needed, so fitting needs care there.)

The filter itself is foam - max life 10K miles. I would - will - make it 5K.

EDIT: Must add that it is just the foam element that needs to be replaced: £17-95 +VAT.

The +8 bhp from the filter was stated with the caution that it was a single car that was tested. More than ever frustrated that cannot get to TDI today now, as would have had their filter put on mine perhaps, to compare with the standard Radium. (That is just my hope - would have tried to persuade them and believe they would have been amenable if time permitted.)

Must confess to feeling relieved that the thread I kicked off a while ago, and that has raised expectations in several, is coming to reality!

Edited by mdavies
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You may get some additional interest from those in the States by posting on the LotusTalk forum. 

Allan, to be clear, I'm not involved with TDI - just another bloke with an Evora. But if it comes to trying to get say 50 people who would want the TDI full system, that would be a good move. A regular LotusTalk poster who was potentially interested would be the best person to mention it in a post there, rather than a stranger like me. I think TDI themselves would be the best people to collect deposits. First they would need to give an idea of cost if say a batch of 50 was made. My phone contact this morning was on a technical basis. On Monday I'm going to put an order in for the Filter unit and find out exactly what they offer. I'm not sure whether TDI will offer a modified screen or if that's up to the buyer. They are a R&D and design/test operation, producing prototypes, not a manufacturer and retail supplier. Others who may have been at TDI on their dyno day today may well be better informed than me. I'll see what they post over the weekend. I'll pitch in with anything else I learn next week.


Just out of curiosity did the tdi test car have the resonator/3rd cat delete pipe fitted?

Khyber, I didn't ask, I'm afraid. Give them a call! Do you know more about the modified screen to accomodate TDI's larger filter. I do know the Radium one has to be changed, but it wasn't appropriate to get into detail on my call this morning. I expect the Radium outline shape and mounting points are needed, but simply with extra metal for a bend. My thoughts on a DIY job involve just cutting into the Radium screen, some sheet aluminium and pop rivets. My guess is that TDI are not planning to provide one - might be wrong.

Edited by mdavies
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My understanding is they have no plans currently to offer a modified screen:-( I guess one would have to order the filter and fit it to identify how much clearance is needed. Only had my radium a few weeks and sadly driven the car hardly 4 times because the weather is rubbish:-(

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Is it only me who is still confused by all of this......

Are you saying TDI have developed a whole new intake (like Radium) which will cost £100 or

They can edit an existing radium for £100?

Or they're not doing anything at all for NA cars?

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There is now good extra information on the TDI Charity Evora Dyno Day thread from the one bloke (Trevor) to make it there yesterday. Any new readers, perhaps from other forums, take a look at both. I'm even more frustrated at not making it because there would obviously have been enough time for them to compare my Radium CAI with their new £100 one - and I could have told you all!

Not clear on why any remaining confusion.

For the NA only:

a) TDI can and is offering a replacement for the K&N filter supplied by Radium at £100 (+ VAT I guess.) See the posts above for more details, including having to modify the Radium screen. And see the other thread as I've just said.

b) TDI has developed a complete new intake. But to produce it at a sensible price needs circa 50 orders. No current plans. See previous posts and now more on the other thread.

For the S engine:

As far as I'm concerned, all that can be said right now has been said. See the previous posts.

Edited by mdavies
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I don't mind posting on LotusTalk. I was just waiting for the information to develop a little bit. And, I'd like to get to a real computer vs an iPad. So, Radium is claiming 21 hp while, if my understanding is correct, TDI is claiming 7hp which I suspect more consistent with what a CAI would generate. I suspect the 21hp gains was really do to running the engine too lean. I'm still not liking my Radium on the lower end. Feels a little unstable at times.

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Does anybody know if Radium themselves are working on an improved product - their website doesn't have any new info on it.

- Or do they think that it is optimised as is?


Anybody Stateside in touch with them?

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Hi guys..


I have tried to keep in touch with TDI about this, this is what they have to say:


"Hi Ryan, there has not been any movement on the intake front quite yet
although we are getting very regular enquires, our aim was to chat with the
guys coming to the dyno day and try to find someone willing to volunteer their
Evora for us to do some final development on but that obviously didn’t happen
thanks to all the snow. The good news for you is that anything on  the
intake system which benefits the NA Evora will benefit your SC model to a far
greater extent."


Kind Regards


Sam Borgman

Technical Director

Edited by rlongthorn
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I recently made an offer of limited use of mine but it was not adequate for TDI's need. Not sure how they would relate development on an S to an NA intake and vice versa, though purely in airflow terms I guess they are the same.

Apart from duration, I would want good visibility of the stress on the engine during their tests, which was an important part of the reason I structured my offer in the way I did.

Who has a company Evora, lease car or similar?!

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Thanks for the link. Do you think the filter looks a little small? I like the way it hooks up to the original intake scoop.



FWIW- It's the same box we run on the Elise that makes over 400 *wheel* horsepower... No problem feeding the 400 crank horsepower Evora;) We did pick up power on the dyno going back to back over the stock air box with (that as equipped with a new KN filter).


The filter we used actually has more surface area than the radium cone KN part, for a point of reference...


I've posted a little more information on the setup on that LT post. 


We've data logged and data logged on the street and our load cell dyno. It took several iterations to get everything happy...Green light for the S cars. Most likely the same  for NA cars, but need to verify. Will have that data some time in near future...





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BOE Fabrications (U.S. distributor for the KoldFire tune) will be coming out with a CAI as well:




That is interesting. I see that the filter looks symmetrical, with a straight path back to the airflow metering and so may be more desirable on that score, and on surface area, than the Radium version, which some people have reported as giving results that depend on the rotational orientation of the K&N filter. (That K&N filter has also been measured as giving a greater pressure drop than desirable - I presume at high flow rates.) 


However I raise a big question mark about where the Koldfire filter is picking up its air.


As far as I can see - and possibly there is some ducting that is not clear from that photo - it is from within the engine bay!  There is no screen that separates the pick-up zone from the engine bay and also constrains the air that comes in through the body grill to flowing around the filter before it bypasses the screen into the engine bay. (As for the Radium.)  My measurements (See Cool or What on the original CAI thread, circa Nov 2011) showed the big difference in temperature between the bay and the Radium air pick-up zone, with the Radium zone pretty close to ambient.  (Provided the car was moving to give natural airflow - important re putting the Radum CAI on a dyno, when a strong feed of air to the intake grill should be ensured.)


The Evora does have a hot engine bay.  Apart from my measurements, I can quote someone working on increasing the NA power: "We got 5 bhp just from leaving the engine hatch open!"


So, however good the Koldfire intake, I ask whether it ensures that ambient air is accessed. (A CAI, or just an AI !)

Edited by mdavies
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Hi Mel. This was recently posted by Turbo Phil on Lotus Talk. #1 may address your question regarding engine heat:

Hi guys,

Not quite ready for primetime, but shouldn't be far...

The goal here was to create an intake that doesn't need tuning (works with stock Lotus tunes and aftermarket tunes), retains the direct "ram air" effect from the body duct on the car, add a little potential for power, make service easier, drop some weight, and make for a better audible note from the intake path. I think we did that with this setup

Couple notes that make it different from current offerings:

1) Lotus did a nice job of giving us a hole in the body work that was designed for feeding outside air to the intake. We retained use of this and have aircraft ducting going from the bodywork air intake scoop to the new filter box. There is no need for a new heat barrier or wall to be inserted in the engine bay.

2) The filter is foam and enclosed in an intake "box", rather than cloth weave in the open engine bay. This has several benefits. Foam breathes better for longer, filters better, and the enclosed box helps to introduce air uniformly to the filter aiding in laminar flow to the MAF sensor, while protecting the filter from damage. It also allows for a tiny bit of that ram air effect (albeit, surely not much)...

3) MAF housing design is much different and is designed to work with stock Lotus programming. We've tested another design out there that wasn't designed with adequate attention to how sensitive this MAF sensor is to air flow. The stock box has no air straightener, the air enters the MAF tube while taking a 90 degree turn, there's a diffuser on the box, etc... bottom line, it' not a simple task to recreate this path to achieve the *needed* MAF values to ensure the car will run correctly at all throttle openings and load levels. If the MAF value is manipulated too far down (such as the case with another aftermarket intake), the engine will be throwing artificially high timing and lower amounts of fuel at the motor. Great for making power in the absence of safety and control of the ECU, but that's surely not the correct way to get power...

This MAF flow design oversight has been a particularly large issue when combined with all cars and tuning, IPS cars, and S cars. There are also issues with "lazy throttle tip-in" and lack of "crispness" in the driving experience. When designing Julian's setup, we built several MAF tubes of various diameters for the car with different internal air "aids" within those tubes to finally get the right combination that produced the correct MAF response in all load sites in the map, made the right power, has exceptionally eager throttle tip-in, etc. It sounds SOOOO awesome as well. The air scoop is just behind the driver's side window on the body work, and OMG, it sounds cool!



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