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Discussion Starter #1 (Edited)
Don't Change Your Supercharger Pulley!

It was one of the early small pulley adapter along with Dave and Darksol... I'll just speak for myself here and say that I was also claiming that I didn't have any issues with the small pulleys and the Katana flash tune. That *was* true... The Katana is a great flash, no doubt... However, DO NOT CHANGE AWAY FROM THE STOCK 3.4 INCH PULLEY or you will eventually be sorry.

I was running a 3.2" pulley, as was darksol, and Dave was running 3.1". None of us have blown engines, BUT....

I started detecting some ping on my tune. WOT seemed OK, but in the middle of the band I could hear the ping. It was faint, but there. Most wouldn't notice it. I pulled the plugs, whispered to them, and saw the peppering---> piston spatter!:eek: Indeed my Katana learned its way lean. Dave did a dyno, as seen in the EFI Experience thread and found the Katana has learned its way grossly lean.

Icing on the cake... This past weekend, darksol and I were tracking at the PCA event. I was getting about 12 mpg and going through about 1/4ish tank of gas per run___ at the track and running hard. Darksol got, get this___ 22mpg!-eek- That's 22 shades of lean all day with 13.5AFRs at WOT on the straights and 14s otherwise... Again, his Katana was also running fine at first, but learned its way lean....waaaaaaay lean, even more-so than mine did...

That's 3 for 3 folks. If you're running a smaller pulley, you had best look at EFI or be prepared for an engine. Otherwise, PLEASE drop back down to a 3.4" pulley and just be happy... I BET this applies to the S cars as well... CX can probably chime in with more experience on them as I don't have one...

I've mentioned in several threads about the error in my ways regarding these pulleys, but I thought it worth its own thread so that others can avoid a popped motor...

I obviously still run the 3.2" pulley but went with EFI to get the job done...

Happy Motoring,

Phil
 

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00 MRS - 2ZZ NA
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And so the prophet charlie was right...

As for intakes on a NA or supercharged car leaning out the engine to destruction... :rolleyes:
 

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Discussion Starter #4
And so the prophet charlie was right...

Indeed.


As it turns out, when it comes to the Lotus ECU, charlie does know what he's talking about:rolleyes:rotfl:D

Never doubted you CX, just needed to see for myself;)

Best,

Phil
 

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Yeah go figure.

So I top off the tank when I get to the track - about 4.1 gallons of 100 octane ($7.35 a gallon!)

I run one 20 minute session. Still 6 bars.
2nd session 5 bars
3rd session 4 bars
4th session 3 bars
127.4 track miles.

I drive home 82.3 miles and the light just comes on as I pull uphill in my driveway (1 bar).

I'm at 1/6 bar right now after driving to/from Phil's tonight.

It's insane!
 

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2008 Lotus Exige-S 240
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For us noobies - so simply stated, with stock electronics you can not get a reflash that is tuned/made for a car running higher than stock boost?

What about if you used mechanical means to increase fuel pressure as boost increased? Back in the 'old days' we used FMUs to do that... basically fuel pressure regulators that increased fuel pressure at a known rate as manifold pressure increased.

Turbophil, your homepage links have more info on it? I couldn't find anything about it.
 

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I was getting about 12 mpg and going through about 1/4ish tank of gas per run___ at the track and running hard. Darksol got, get this___ 22mpg!-eek- That's 22 shades of lean all day with 13.5AFRs at WOT on the straights and 14s otherwise... Phil
For pit stop strategy I figure on 7.25 MPG with my 240 Cup car.-poke-
 

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Discussion Starter #8 (Edited)
As it currently stands there are no flashes that I know of which are designed to run with a smaller pulley... You can play with the fuel pressure all you want (will require a different fuel rail and PR with return line to do that) but the eCU will still eventually lean the mix back. remember it ultimately controls injector pulse width....

There are some fine tunes available that will allow NA cars to convert to Forced induction and run pretty good... conservative and good... There's tunes that allow the OEM S cars to get some better performance as well (Gotham tune in particular).
However, If you want that extra 30hp or so that you can get out of a hotair FI car, you have to go to standalone at the present time. The engines and setups vary enough from car to car that Charlie likely has to leave that much room in the tune... His self control to not "overtune" a car must be pretty darn good... as what works on one car in the peak of the envelope will not work on another...

Sorry about not having the info on my website... I need to revise, edit, and add a bunch of items to the tech library. THose are better winter projects though:rolleyes:

Just to be super clear here... I'm not saying there's anything wrong with the Katana tune or kit, whatever. It's great. Just don't mess with the pulley. The tune is designed for a 3.4" pulley and the stock air box. Make sure you have those two items in place and enjoy it!:up:

I'm quite confident that Fred doesn't recommend deviating from the the stock pulley or airbox either for the same reasons...

Best,

Phil

For us noobies - so simply stated, with stock electronics you can not get a reflash that is tuned/made for a car running higher than stock boost?

What about if you used mechanical means to increase fuel pressure as boost increased? Back in the 'old days' we used FMUs to do that... basically fuel pressure regulators that increased fuel pressure at a known rate as manifold pressure increased.

Turbophil, your homepage links have more info on it? I couldn't find anything about it.
 

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For us noobies - so simply stated, with stock electronics you can not get a reflash that is tuned/made for a car running higher than stock boost?
I'm sure Charliex could custom tune anything. But the STANDARD tunes he offers are set up for a particular configuration.

xtn
 

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yep just basically saying what i've said all along, don't change them, in winter it'll seem ok, but as soon as the hot weather hits.

we are planning on doing smalley pulley tunes at some point, or i can do a custom tune for you for a lot less than a standalone.
 

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What have people been experiencing w/ the Exige S and smaller pulley?

3,400 miles on my Exige S w/ 3.1" pulley and rls Intercooler, everything seems fine (pulled plugs too)... still being cautious. Ran in all altitudes (up to Estes park) and temperatures up to 90 F, no issues.

(Nervously watching my wideband, of course).

As a data point, 3.1" on the '07 Exige S is about a 6/10 psi increase when combined w/ the rls Intercooler. Rembmer that the stock pulley on the Exige S is 3.228" so 3.1" isn't a big change.
 

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Math doesn't change so the reasons this happens don't change either (which is why we have math so we can do away with believing it when you see it ;) ) , so its the same effect but how much is dependant on the size of the pulley swap, time , temperature etc.

The S is set fairly lean to start off with so you're playing with fire.

If its not a big enough change to effect the boost, then there isn't much point changing it either.
 

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Math doesn't change so the reasons this happens don't change either (which is why we have math so we can do away with believing it when you see it ;) ) , so its the same effect but how much is dependant on the size of the pulley swap, time , temperature etc.

The S is set fairly lean to start off with so you're playing with fire.

If its not a big enough change to effect the boost, then there isn't much point changing it either.

So that's how math works.

Exige S: stock 3.228" pulley to 3.1" pulley, circumference changes from 10.14" to 9.74", or a 3.9% increase in pulley speed.

Katana: stock 3.4" pulley to 3.2" pulley, circumference changes from 10.68" to 10.05", or a 5.8% increase in pulley speed.

Is it possible that w/ the Katana tune, the injectors are already near clipping, and that adding the smaller pulley makes the injectors run out of juice (no pun intended) before the ECU can get enough fuel through the injectors to make up for the increased airflow?

I'd like to test the Gotham w/ the Exige S / really light stuff Intercooler / 3.1" pulley, let me know if you want to want to participate.
 

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As I recall, the Katana does not have an intercooler. You will see very high intake air temperatures which are probably causing the detonation.

Perhaps this is why the Exige S w/ intercooler isn't experiencing the same?
 

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So that's how math works.

Exige S: stock 3.228" pulley to 3.1" pulley, circumference changes from 10.14" to 9.74", or a 3.9% increase in pulley speed.

Katana: stock 3.4" pulley to 3.2" pulley, circumference changes from 10.68" to 10.05", or a 5.8% increase in pulley speed.

Is it possible that w/ the Katana tune, the injectors are already near clipping, and that adding the smaller pulley makes the injectors run out of juice (no pun intended) before the ECU can get enough fuel through the injectors to make up for the increased airflow?

I'd like to test the Gotham w/ the Exige S / really light stuff Intercooler / 3.1" pulley, let me know if you want to want to participate.
The math quote was for phil.

The injectors aren't maxxed out on the katana, plenty of room left as we run much higher HP/TQ cars on the same ones and as far as i know phils still running that size but he's corrected the AF for that pulley.

alter one side of the equation, change the ratio, all we're seeing here is real world proof of the math, just think about what it is that you want to achieve, rationalisation of something already done or some other goal, or proof of whats really happening.


what causes the detonation is incorrect AF ratios, not the lack of an intercooler.
 

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Discussion Starter #17 (Edited)
T-

About 1,500 miles. A good chunk of those miles were during the cooler months. I probably had 2,000 on the 3.2 before I concretely decided that I had a lean condition. The problem was that I was only look at WOT AFRs. As it turns out, I was mainly pinging in the mid range part of the band where the highest pressures are. Darksol and Dave are jsut plain lean everywhere in the band now but don't seem to have as loud of a ping... 'er they don't hear the ping anyway... They certainly have a couple K miles on their tunes as well...

The katana kits are running 440cc injectors that can make way more power than what a 3.2 pulley can blow the air for, so we know it's not an injector issue. There's plenty of injector to spare at the 240-250whp figure, as the 440s are only running about 75% duty cycle at that level with the stock FP and pump, Sir Wallace is correct- it's all in the math;)

In the end, I'm happier with the standalone, but it sure isn't right for everyone. But the point of the thread is that changing anything on the intake side of the engine can be *potentially* dangerous for a learning ECU that's not tuned for those intake changes...

Best,

Phil
 

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Discussion Starter #18
The math quote was for phil.
Ya, Ya, I caught that. What do you know-poke-rotfl :D ;) You have to understand, I'm really close to Missouri, where the state slogan is the "Show Me State."

Cheers,

-P
 

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we are planning on doing smalley pulley tunes at some point, or i can do a custom tune for you for a lot less than a standalone.
Cool. Was also hoping my 240's larger injectors (true?) would help with this as well (able to provide better atomization while delivering more fuel)?

For other cars (most of my experience is 'old school') I am just accustomed to being able to add a little boost when the car comes with a stock turbo/supercharger. I was suprised to read that the ECU on the Exige might be unable to do that, esp when it can handle going from N/A to blower car using the same electronics (w/new tune).

So, hopefully one day I will take the step and call up Charlie - up the boost a few lbs, and reflash my ECU with a 'more boost' tune to make it all 'OK'. Ugh, I am already :drool:.
 

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What about if you used mechanical means to increase fuel pressure as boost increased? Back in the 'old days' we used FMUs to do that... basically fuel pressure regulators that increased fuel pressure at a known rate as manifold pressure increased.
Not on the stock lotus fuel system. It's a returnless system. That is one of the changes I am making to mine. Converting to a return system and adding a 1:1 regulator
 
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