A&Q about Lotus
Q:
Apex, that info is form Komo-tec website
After the way you bash them, it makes me wonder about thier reputability
A:
Very interesting to compare what people think seloc-etalk:
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If youre going to go s/c, go with a positive displacement application. The boost on a centrif. system is not linear. It's exponential relative to the impeller speed, meaning it looks something like what I have posted below. Basically you get hardly any boost down in the low rpms (although you do get drag), and most of your boost/power will be made in the last 1k or so of the rpm band. Its just not a great kit for this motor. A properly matched turbo would walk all over a centrifugal application.
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I'd rather not think of what I post as bashing. I'm presenting my professional opinion in response to theirs. There's been a lot of discussion about this issue among the tuner community. The fact is, supercharging was much easier to get right at one time. But turbos have evolved so much that we've just about abandoned s/c in any application where packaging is not an issue.
I worked a lot with Dinan, and when Steve was working on the forced induction solution for E46 M3's, he went supercharged. His reason was that for the required level of boost, the packaging and installation was simple. He needs to rely on dealer to do installations so that's a big factor.
So I'm not trying to say there's no place for supercharging, I'm just saying that once the development is done, TC is the better engineering solution. And I don't buy people's claims on the superiority of SC.
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Can you put me in touch with your tuner? I'd like to know what he'd done differently. Do you have a non-learning ECU? Have you been able to disconnect the O2 sensors without triggering a code? Or are you using a split-second type 02 controller with the Emanage? We've theorized that might all work, but its easier and we get better results by just piggybacking a standalone.
He'll be in touch.
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Originally Posted by Ginetta
If youre going to go s/c, go with a positive displacement application. The boost on a centrif. system is not linear. It's exponential relative to the impeller speed, meaning it looks something like what I have posted below. Basically you get hardly any boost down in the low rpms (although you do get drag), and most of your boost/power will be made in the last 1k or so of the rpm band. Its just not a great kit for this motor. A properly matched turbo would walk all over a centrifugal application.
I won't argue with your statement. The Rotrex may not be any exception either.
It's drive is a little different though. And it is essenially a small lightweight Holset turbo with a belt drive. Maybe it could spool up quicker than typical belt drive centrifugals. There's a euro outfit developing a transmission drive in conjuctions with Rotrex. I think it's a 2 speed that gets the turbine up to speed quicker. Good things come to he that waits!
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Originally Posted by MikeW
I won't argue with your statement. The Rotrex may not be any exception either.
It's drive is a little different though. And it is essenially a small lightweight Holset turbo with a belt drive. Maybe it could spool up quicker than typical belt drive centrifugals. There's a euro outfit developing a transmission drive in conjuctions with Rotrex. I think it's a 2 speed that gets the turbine up to speed quicker. Good things come to he that waits!
I dont like the centrif. blowers because I had one on a car and it just wasnt my cup of tea. It is a simple solution though, I will give it that. Just not ideal imo I guess. I always thought it would be interesting to overdrive the supercharger and then vent the excess via a wastegate a la a turbo setup, but I never got around to looking into it. You would probably have to spin the s/c out of its efficiency range to make the earlier spool up significant. Either that or use a huge blower which would prob have too much drag.
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Originally Posted by TrackRat5
Originally Posted by apex speed tech
Can you put me in touch with your tuner? I'd like to know what he'd done differently. Do you have a non-learning ECU? Have you been able to disconnect the O2 sensors without triggering a code? Or are you using a split-second type 02 controller with the Emanage? We've theorized that might all work, but its easier and we get better results by just piggybacking a standalone.
He'll be in touch.
I'm not doing anything different than I normally do with other high compression turbo cars, such as 350Zs (400hp+), S2000s (400hp+) etc. I'm modifying the output injector pulse width against the manifold pressure. Same for timing. The ECU is a standard ECU with multiple fuel trim zones. The map is modified for the injectors with accurate size and lag times and some compensation for different flow rates at different pulse widths. O2 sensors are all in and working fine completely stock. Driving around, all long and short term fuel trims are around 0 naturally because we took the time to figure out exactly what is needed. It took about 400 miles of driving to get everything dialled in correctly in closed loop. The lotus ECU also does closed loop stiocheometric fuel control up to around 4000 rpm at wide open throttle so basically you need to supply the ECU a modulated voltage to simulate 14.7:1 AFR during boost conditions. It must be modulated because if you are a little off the fuel trim will start to swing in one specific direction undoing all your hard work. On top of that we set the EU up to control the VVTL solenoid which requires some EU jumper changes and a small circuit to handle the solenoid and VVTL oil pressure switch. That's about it for now.... Coming up will be a custom made free flowing exhaust and cam phasing control to unlock the horsepower at high rpm (for those following the other thread)
Of course we are not cheap, but we do a thorough job and customers have to be prepared that things may take some time and accept that they are trying to make the engine do something it was never designed to do. We work on a private contract basis so it's not your average tuner 'shop' etc. it is by appointment and agreement only.
Finally, I own my own dynapack dynamometer so every cell of the maps is tuned specifically
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Originally Posted by Ginetta
If youre going to go s/c, go with a positive displacement application. The boost on a centrif. system is not linear. It's exponential relative to the impeller speed, meaning it looks something like what I have posted below. Basically you get hardly any boost down in the low rpms (although you do get drag), and most of your boost/power will be made in the last 1k or so of the rpm band. Its just not a great kit for this motor. A properly matched turbo would walk all over a centrifugal application.
Page 2 has dyno graph. Although it does look exponential, its still pretty linear. And torque curve is not that much different from eatom blower, which is perfectly flat.
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Originally Posted by Ginetta
I dont like the centrif. blowers because I had one on a car and it just wasnt my cup of tea.
What would you say you didnt like about centrifugal comparig to other s/ces?
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Originally Posted by apex speed tech
I'd rather not think of what I post as bashing. I'm presenting my professional opinion in response to theirs. There's been a lot of discussion about this issue among the tuner community. The fact is, supercharging was much easier to get right at one time. But turbos have evolved so much that we've just about abandoned s/c in any application where packaging is not an issue.
It was a joke
You see, my main concern is not with lag or quality of the kit, but with ecu and tuning.
Ive searched this forums all over, but no-one can give me the answer i want.
1. FF is using piggy back. They had problems with idle and stalling initially and ecu adaptation. Now those few people who use it, say the problems have been resolved. I called FF and they say no problems. But i presonally cant see how a piggyback can manage to give correct cammands to full ecu at all rpms and all throttle positions.
On the other hand, if i choose to put stand alone, its either 6k, which is pathertic, or do a map myself, which very risky, since there are not that many great specialists in Moscow and they can mess up.
I assume fine tuning the map for local conditions can be done in and avaragrely good tuner shop?
2. Dyno graph. Dyno graph given here was faulty. Ive done a search for dynos and they all seemed to actually be very nice! but they all showed max power around 245-250 bhp. In threads they didnt mention (or i didnt find) if it was at wheels or with programmed loss. If it was at wheels, it seems a bit too much, if loss is accounted for, it looks too little.
Also, in this thread with a/f ration:
Fulel ratio at low rpms seems very lean!
All this + as far as i understand two kits have poped during early days, makes me very worried about turbo!!!
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at this point all i have to say is that i'd take a FF275 kit, but considering you're in russia which is a bit tentative place to have a unique system, and which has the most insanely hot girls per capita than i've ever seen in my entire life, and i've been lots of places, i'd say stick with NA and spend the money on GIRLS GIRLS GIRLS!
After my trip to St. Petersburgh, it's almost entirely depressing going out in San Francisco. It's like a baren waste land out here. See... we need FI to make up for boring women (present company excluded). You shouldn't even be thinking about this! You're just spoiled! Shame on you!
I wish i could find a decent mechanic for my G500 (which are common cars in russia, especially for the mafia) and you wish you could get local service on some FI. Wanna trade places? How about a visitor? My biggest gripe in St. Pete's was not knowing anyone.
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Hey Val,
I don't know if you ran across this thread, it contains some interesting info and comparisons:
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Girls is good, but right now im not in need of any additional supply
Would really appreciate if someone would answer my two questions from above post especially from forced fed.
Originally Posted by Val
1. FF is using piggy back. They had problems with idle and stalling initially and ecu adaptation. Now those few people who use it, say the problems have been resolved. I called FF and they say no problems. But i presonally cant see how a piggyback can manage to give correct cammands to full ecu at all rpms and all throttle positions.
On the other hand, if i choose to put stand alone, its either 6k, which is pathertic, or do a map myself, which very risky, since there are not that many great specialists in Moscow and they can mess up.
I assume fine tuning the map for local conditions can be done in and avaragrely good tuner shop?
2. Dyno graph. Dyno graph given here was faulty. Ive done a search for dynos and they all seemed to actually be very nice! but they all showed max power around 245-250 bhp. In threads they didnt mention (or i didnt find) if it was at wheels or with programmed loss. If it was at wheels, it seems a bit too much, if loss is accounted for, it looks too little.
Also, in this thread with a/f ration:
Fulel ratio at low rpms seems very lean!
All this + as far as i understand two kits have poped during early days, makes me very worried about turbo!!!
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Actually, im quite surprised that forcedfed ignores this thread all together. Not that they were very friendly when i called them either.....
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There seems to be quite a bit of info to tap into with this community. Good for us.
I can't claim to be a tuner or as expert as many others on this thread. I do have some experience with dealing with the particulars of owning / modding / tracking a turbocharged vehicle at altitude (which presents its own unique issues).
Anyway, my $0.02, and IMO...
1) I personally wouldn't turbocharge a motor that wasn't designed for the purpose from the outset. I don't care how good you are and how much money you've got, your ability to out-integrate Porsche, Audi, BMW (the 335i is sublime), Bentley (the Continental powerplant is beyond sublime), and all of the other manufacturers of turbocharged vehicles is a pipe-dream at best (although the Chevy Sprint Turbo could have used some help ). "Good Enough" is largely self-defined however, and YMMV. So, if you've done it and you're happy... good on you.
1a) I would add a supercharger though.
2) I believe Dinan moved from turbocharging to supercharging based on the fact that engine internals (i.e. lower CR pistons, oil squirters, etc.) didn't need to be done as it related to supercharging.
3) While additional power / top-end would be nice, IMO our motors need more torque / low-end, at least at the track. If you want to go fast on the street, get an AMG 55 or 63.
4) Anyone considering forced induction should at the very least read Corky Bell's Maximum Boost and Supercharged. Pretty terrific reads IMO.
5) Centrigugal blowers (i.e. belt driven superchargers) = the worst of both worlds.
6) I wish Lotus would have dropped something a little bigger (2.0 liter Honda motor?) in our cars. All I want is 225 (ok, maybe 250) naturally aspirated horsepower. Sigh.
Do check out Corky Bell's books though.
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Val,
You shouldn't be afraid of doing your own map. It isn't that hard with a standalone if you can be meticulous about it.
It's not rocket science, it's just incremental trial and error. The best way to do it is to install the standalone and larger injectors first and have it run your n/a engine. You'll learn how to get things done without worrying about boost. Once you're confident, slap the turbo on and you already have half of the tuning done.
Apparently, the only knock on the cheaper Hydra is that the software sucks. $6k for an ecu is just plain silly (unless you have money to burn). Perhaps wait for Apex to come up with their ecu solution.
Frank,
Re: point #2, There's no difference as far as internals go between turbo and s/c. Boost is boost. You can have a 4psi turbo just as easily as you can have a 4psi s/c. The load on the engine is actually a bit lower with the turbo (no belt).