My CN Exige S went to the Dyno again today to see what [color:#3333FF] difference[/color] fitting a 2Bular 4-1 + decat+ trackday chambered silencer has made against the standard Lotus manifold + cat + Lotus stage 3.
There have been [color:#FF0000] NO[/color] other changes to the car and the same Dyno was used.
The only variable is the atmospheric conditions (which were not favourable today … high humidity 80%) As such these figures are very conservative.
Results :
A [color:#33CC00] gain[/color] of 9.7 BHP Power
A [color:#33CC00] gain[/color] of 11.3 Lbft of Torque
The mixture was slightly [color:#FF0000]Rich [/color] ending up at 12
Sitting in the reinforced viewing room,the noise at 8800 rpm was [color:#3333FF] the best engine sound I have ever heard[/color] outside of F1…Seriously on another level. A truly wonderful howl… proper race car.
Yes what a day, Johns results were fantastic! and I think the AFR at WOT settled a little argument.
I had a cracking day and learned alot about what not to do when going on a dyno This ment I did not get the result I really wanted as I managed to get my intercooler completely heat soked (yes I know) before the power run…
I opted to go first, my thoughts were that as the car had been driven and the engine was warm my IC was still cool due to the fact it had been moving. I thought if I had had to warm it back up standing the IC would heat soke quicker… not the case.
Problem is that due to being driven the engine bay is still warm and the the car goes straight inside where it is warmer and more humid (today at least) so the heat very quickly gets into the IC, as the dyna pack is a hub dyno it takes time to remove the wheels and rig her up and by this point I quickly realised my IC was getting pretty hot.
John brought a leaf blower that we thought would help but as I was the first to test it I only realised while blowing it on the IC it was blowing hot air
So I had to do the run with a totally heat soked IC
Leson two was that if given the option tell them to rev it all the way… they asked and I bottled it so my first power run ended up at 8200RPM, this was my best at 267.2bhp.
By the second run power was dropping away quicker than a libyan dictator down to 263bhp.
I think this pretty much shows how much the ECU retards the engine when it gets badly heat soked.
The intercooler was as hot before the first power run as I have ever felt it, that was after a heavy track session on a hot day at anglesey. When I drove it home I gave it the beans but it always remains very cool to the touch.
So what I have taken away is that I am happy my car is good for the mid 270’s when not heat soked and even in its worst case its making good 260’s
We found with John and Marks car that they stayed nice and cool outside but the engines heated very quickly as they had not been driven that long before, there IC’s were much cooler before the runs and that seemed to make all of the difference.
Marks car was only converted last week and has the CN’s 260, TRD airbox and a 2bular GT3. Other than that its stock. His result???
297bhp!!!
Work that out. I cried into my chips.
Same dyno, same day, same correction
So there you have it, don’t go first, don’t use a leaf blower and do rev it all of the way
Oh my AFR was 12.5 with the larini silenced de cat but I don’t think that will be lasting very long. The proof of the pudding is in the eating and Johns car made 10bhp and more torque all the way through and does not need a re map. And Marks car is just a freak of nature
Hey all, interesting numbers indeed. Increased power was a question I asked Matthew at Silverstone Lotus today (nice guy by the way, very helpful) The big Fox advised me to fit Jim’s manifold, and complete exhaust system from the off, so I went for it…today I collected her, and wow does she moan! I had the lot fitted during the 1000 mile service to save on costs.
My observations are that the throttle is now really smooth and responsive. I have the 260 RGB and have made no other mods. The ECU I guess is re-mapping itself? I get the occasional pop as I quickly come down through the gears quickly, a little over-run i guess. My understanding is the RGB has different injectors and fuel pump, easily allowing for the 2ubular mod.
one other observation… she seems to rev higher, meaning rapid gear change through 3 thru 6. (and I mean quick!) Maybe a different gear ratio needed? does anyone know if the 260 Cup has different ratio’s?
just thought of other things i should tell you guys, not sure it makes any difference though, but I’m running cooler… due to crumbling discs (in my spine) I have had a soft top fitted to the lady, (enabling me to get in and out more easily)… my engine running temp is normally around 89 degrees, today post new exhaust system I’m running 86 degrees? Today was not particularly different to previous running days? I guess the exhaust gases are just exiting quicker through Jim’s system, thus less heat soak? I’m guessing here!
This ment I did not get the result I really wanted as I managed to get my intercooler completely heat soked (yes I know) before the power run…
