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Discussion Starter #21
I finally got around to getting my 2bular exhaust system installed on my Evora. I decided to have VSA Motorsports do the install, rather than do it myself. They have done the installs before, and know the routine, so they could do in a couple days what would take me a week. Thanks to Alan, Sergio, and Stephan for their expertise, and attention to detail !

Aside from some minor adjusting, the system install was straight forward, but time consuming. It took 2 full days, start to finish. Extending the O2 sensor harnesses was easy, but took a long time to figure out the routing and required lengths. The 2 Post Cat sensors, which had to be extended, were lengthened about 3-4 feet, to allow a neat routing along the rear sub frame. They were mounted using adel clamps, screwed into rivnuts placed in holes that were already in the sub frame. See Photos.

The weight difference between the Stock Manifolds-Downtube- Cat and Stock Muffler to the 2bular Headers-Downtube-Metallic Cat and Lotus Sport Muffler was 19.74 lbs., of which 13.5 lbs was the difference in the mufflers.

The sound of the 2bular system and Lotus Sport Muffler is amazing ! It has a soft rumble at idle, and has a full, but not excessively loud tone on easy acceleration. The more throttle you give it, the more robust it gets, and under full acceleration it sounds serious. The good news is that cruising at 70-75 MPH in 5th or 6th gear, at 2,500 RPM, you can barely hear the exhaust note. It is definitely not objectionable for conversation or listening to the radio. However, as soon as you accelerate at all, or load it going up a hill using more throttle, the sound picks up.

I did Dyno runs with the completely stock exhaust just before the install, and will repeat them on the same Dyno with the new exhaust system after a few hundred miles to allow the ECU to adjust. The good news is that it NEVER threw a CEL after the installation. I'll post the before and after Dyno results here, after I get them.
 

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Looking forward to dyno results...how many hours total for the install?
 

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Don, looking good. Very clean install. Congratulations.
 

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Very nice, pretty bits, Don. Plan on doing a dyno?

BTW, your undercarriage is immaculate. I'm jealous :) How do you keep it so clean!?

My car is filthy by comparison.
 

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VSA, what do you charge for such an install job? if the gains are significant, it may be very appealing to others like myself to join in on the mod fun.
 

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Phew! That is one clean car Don! I can see your install guys got the heat-shields exactly right - well done to them. :cool:
Lambda wiring extensions: I have Ray on your side of the pond on the hunt for a supplier for these - hopefully someone who works to the same standard as VSA!
I've e-mailed you some info on the headers.
Our test mule didn't have the Radium intake set-up - didn't want any skewed results. We've since found combining the 2bular headers/downpipes + Radium is a step too far for the ECU - you need an ECU re-flash to get the best from that combo - ah well.
 

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Discussion Starter #31 (Edited)
After driving my Evora for 350 miles, with the 2bular Exhaust system, I did the post installation Dyno runs today.

The graphs below show the Pre vs Post system Dyno results, in the Standard and SAE formats. The Pre was with a completely stock Evora, as delivered. The post is with the 2bular Headers-Downpipe-Metallic Cat and a Lotus Sport Muffler. The only change was the exhaust system, NO CAI, and NO ECU re-flash tune.

The dyno technician said that the drop in HP and torque between 3,200 - 4,300 RPM, in today's Post run, was due to his accelerating it from 2,600 RPM today vs 3,200 RPM last time. Starting at the lower RPM apparently "loads it up" initially.

The Air / Fuel graph shows how rich the stock Pre set up runs, topping out at the maximum 10.0 lambda at 5,900 RPM. On today's Post runs, they could not get the lambda O2 sensor to work, on any of the 3 pulls we did. BTW, ALL of the dyno runs were very consistent on each day's runs, within 1 HP.

The net gains were 13.26 Maximum Wheel HP, and 5.78 Ft Lbs of torque. Using the Standard 263.15 HP, and figuring a 15% drive train loss, that equals 309.6 Engine HP. Even with a low 10% drive train loss, it calculates to 292.4 Engine HP. But more important than the absolute number is the relative gain. The 13.26 Wheel HP gain equals 15.6 Engine HP gain. This is a 5.3% HP gain !

So, if you want more power, along with an amazing exhaust note, go for the complete Header-Downpipe-Metallic Cat System. And, I'm sure there is more HP available with the addition of a CAI and ECU Tune.
 

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Thank you Bobsy - great write up and dyno's. The headers will be my next step - though I am still wanting to see if a true twin setup (no collecting each bank of 3) will be better. Only one way to find out if no one else chimes in with their results lol.
 

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That is very impresive Bobsy! Thanks for sharing and going to all the work to install and test.

I am not wanting to go that far for a Exhaust mod for my Lotus , but I am interested in the Radium CAI with the Sector 111 pipe. See image below, and if anyone here has done this combination, I would appreciate your thoghts.
 

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Interesting.
Seems the Radium CAI and Exhaust are giving similar numbers as the header & exhaust without CAI? This being based on other numbers seen.
RAMTIN did the all of the above solution, correct? CAI, Header, Exhaust and tune correct?
What are the pros and cons of more airflow in v more airflow out?

I had the pipe and CAI. Effect of pipe is minimal. Slightly richer sound and maybe 1-2 hp max. I went straight to exhaust while car was apart. Just had to...
 

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Don, Nice results and thank you for sharing the information. Not only are the peaks higher but the curves are both smoother and fuller, i.e. the torque and power increase is almost constant from 4700 rpm up so it is something useable through a full gear acceleration, not just a “peak” number.

So in sum -20 lbs and plus 5% power!
 

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Discussion Starter #36
I am not wanting to go that far for a Exhaust mod for my Lotus , but I am interested in the Radium CAI with the Sector 111 pipe. See image below, and if anyone here has done this combination, I would appreciate your thoughts.

If you do the CAI and the "Decat" pipe, Please do before and after dyno runs, on the SAME Dyno, so we can get an accurate measure of real gains.
 

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Discussion Starter #37
Don, Nice results and thank you for sharing the information. Not only are the peaks higher but the curves are both smoother and fuller, i.e. the torque and power increase is almost constant from 4700 rpm up so it is something useable through a full gear acceleration, not just a “peak” number.

So in sum -20 lbs and plus 5% power!
Julian,
You make an excellent observation that the HP and Torque gains are CONSTANT from 4,500 RPM to 7,200 RPM. So, you feel it through the range, not just at a peak spot. Although the 13.26 Wheel HP gain is not as much as I anticipated, it feels like more.
 

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I will be doing my pre and post install dyno runs in December with an install of headers and Hi flow Cat w or w/o rececpt ofg my 2ubular downpipe. Will be somewhat different as post will be with a Koldfire/Komo-Tec tune.

PS Don, my muffler looks much better under your skirts than in my box.
 

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. . . I am interested in the Radium CAI with the Sector 111 pipe. See image below, and if anyone here has done this combination, I would appreciate your thoghts.
I have the Radium CAI, decat pipe, and Kold-fire tune. My best estimation (based upon a Dyno Dynamics "heartbreaker" dyno) is that I'm putting out ~310-320BHP. The Radium needs no further praise. The decat pipe, while probably not adding much in the way of HP, does increase the sound slightly, add a bit of that wonderful unburned hydrocarbon smell, and most importantly add a few minor pops and crackles on deceleration. The Radium/decat combo you're considering is so (relatively) cheap, you can't go wrong. Personally I want to get those primary cats out of there too, but that's considerably more difficult/expensive than removing the third cat.
 

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I have just had the Radium CAI and Larini 3rd cat replacement pipe done. It sounds great when pressing on and as quiet as stock when on the motorway in the 'region' of 70mph.

Sadly I did not do a power run before I got it fitted, but I am giving and demo to a friend with an NA in the same town as me. His is bone stock, so I will see if he would like to try a shoot out on a local dyno. Watch this space.

I was also very lucky to get a ride in Don's car when I was in San Diego last week. (Thanks for being such a great host BTW!). I can confirm that it sounds absolutely fantastic, really ballsy when pressing on and not massively loud when cruising but certainly louder than stock. I think for Don and the bulk of Evora owners who use it as a special occasion car - it is perfect.

For me tho' the 2bular+lotus sports back box is a little too loud during cruising as I use mine every day and rack up about 1000 miles a month, so I think my approach - for more power when the warranty (or Lotus) runs out, will be to go with the 2bular manifolds/headers, down pipe and sports cat and stay with the stock Lotus back box. That is, unless the rumoured valved exhaust option for pre 2012 NA cars appears from Lotus-Janspeed - I saw the prototype at the Goodwood festival of speed on the Janspeed stand this summer and it looked great!

Exhausts are tricky things and very much down to personal taste! I think I want my cake and to eat it - very quiet cruising - rorty when pressing on and power gains, all at the same time. When it comes to exhausts I recommend hearing one in person if you can!
 
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