IS250 S/C installed
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Driver
Joined: Oct 2007
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From: Greece
IS250 S/C installed
I finally installed the LMS kit.
It's working very good and smoothly.
No problems at idle and no stalling at all.
Noticeable difference in all rpm range.
I had only the time for a quick ride after install but noticed that the motor revs a lot quicker. I reached 250 km/h very easy.
AFR PLX gauge shows 12.5 to 13.5 at WOT which means that the mixture is reach and safe enough.
C2 Procharger and Synapse bov sound great.
Synapse works like a charm.
It was a direct bolt on with a small issue on compressor's intake pipe (small gap between compressor and engines headers).
I'll get it to dyno asap to see the results.
It's working very good and smoothly.
No problems at idle and no stalling at all.
Noticeable difference in all rpm range.
I had only the time for a quick ride after install but noticed that the motor revs a lot quicker. I reached 250 km/h very easy.
AFR PLX gauge shows 12.5 to 13.5 at WOT which means that the mixture is reach and safe enough.
C2 Procharger and Synapse bov sound great.
Synapse works like a charm.
It was a direct bolt on with a small issue on compressor's intake pipe (small gap between compressor and engines headers).
I'll get it to dyno asap to see the results.
Last edited by pepos; Oct 3, 2010 at 03:28 PM.
That's pretty lean for a boosted application from my understanding...I know the 2JZ folks shoot for AFRs in the 11s generally at WOT... Maybe one of the few LMS-boosted 350 guys can chime in though as I suppose the readings on a DI motor might look different for some odd reason.
Last edited by Kurtz; Oct 3, 2010 at 08:36 PM.
Thread Starter
Driver
Joined: Oct 2007
Posts: 191
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From: Greece
That's pretty lean for a boosted application from my understanding...I know the 2JZ folks shoot for AFRs in the 11s generally at WOT... Maybe one of the few LMS-boosted 350 guys can chime in though as I suppose the readings on a DI motor might look different for some odd reason.
I use sensors from PLX Devices which are quite accurate i think.
If the 350 guys can hepl it would be great.
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Where did you get 13.2-13.8 as a target? As I say that's very lean compared to most target AFRs I'm familiar with on boosted cars for WOT, but it's certainly possible the ISx50 engines are ok running quite a bit leaner than many others even boosted.
Thread Starter
Driver
Joined: Oct 2007
Posts: 191
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From: Greece
I don't doubt the accuracy of your 13.5 reading, I was doubting the safety of 13.5 as a reading.
Where did you get 13.2-13.8 as a target? As I say that's very lean compared to most target AFRs I'm familiar with on boosted cars for WOT, but it's certainly possible the ISx50 engines are ok running quite a bit leaner than many others even boosted.
Where did you get 13.2-13.8 as a target? As I say that's very lean compared to most target AFRs I'm familiar with on boosted cars for WOT, but it's certainly possible the ISx50 engines are ok running quite a bit leaner than many others even boosted.
I installed PLX DM-100 OBDII along with 2 AFR sensor modules one for each bank a week before the S/C.
13.2-13.8 is the range the car was working at WOT that week (atmospheric).
Today i took the car for trip to a city 200 miles from home.
On return the ECU corrected again and worked between 11.5-13 at WOT.
On city traffic boosted or not the ECU works near stoichometric 14.7-15.2
At idle 14.7-14.9
λ (lamda) value on both banks 1.00-1.01 at idle, 1.09-1.14 at WOT.
AIT at WOT is 54 degrees Celcius with an ambient of 27 degrees Celcius.
On city traffic AIT is 31 degrees Celcius.
EGT at WOT 890 degrees Celcius boosted or not.
Boost reading at WOT 0.38 bar.
So it means that if the car works 13.2-13.8 normal, there should be no problem to work 13 boosted.
Up to now the car works fine. So i beleive these readings are within safety limits.
I think that Steve from LMS was correct when he said that as long as you keep it up to 5 -5.5 psi with the intercooler on and running on premium, the ECU can handle the extra fuel needed.
It's very fun to drive the car.
Especially at high revs 4500 and above the car is something else.
I always use premium gas.
The kit was installed in a friend's garage and not in a shop.
I will probably dyno the car tomorrow.
Last edited by pepos; Oct 4, 2010 at 10:02 AM.
You generally want to run richer on boost than you do NA.
http://www.turbobygarrett.com/turbob...tech102.html#e
A supercharger would have the same general principles applied to it though, in that you want to run richer on boost than you do NA.
6 psi might well be little enough boost to get away with it safely though.
Most boosted guys worrying about keeping AFRs in the 11-ish range are running, let's just say, a lot more than 6 psi
http://www.turbobygarrett.com/turbob...tech102.html#e
Generally, normally-aspirated spark-ignition (SI) gasoline engines produce maximum power just slightly rich of stoichiometric. However, in practice it is kept between 12:1 and 13:1 in order to keep exhaust gas temperatures in check and to account for variances in fuel quality. This is a realistic full-load AFR on a normally-aspirated engine but can be dangerously lean with a highly-boosted engine.
Let's take a closer look. As the air-fuel mixture is ignited by the spark plug, a flame front propagates from the spark plug. The now-burning mixture raises the cylinder pressure and temperature, peaking at some point in the combustion process.
The turbocharger increases the density of the air resulting in a denser mixture. The denser mixture raises the peak cylinder pressure, therefore increasing the probability of knock. As the AFR is leaned out, the temperature of the burning gases increases, which also increases the probability of knock. This is why it is imperative to run richer AFR on a boosted engine at full load. Doing so will reduce the likelihood of knock, and will also keep temperatures under control.
Let's take a closer look. As the air-fuel mixture is ignited by the spark plug, a flame front propagates from the spark plug. The now-burning mixture raises the cylinder pressure and temperature, peaking at some point in the combustion process.
The turbocharger increases the density of the air resulting in a denser mixture. The denser mixture raises the peak cylinder pressure, therefore increasing the probability of knock. As the AFR is leaned out, the temperature of the burning gases increases, which also increases the probability of knock. This is why it is imperative to run richer AFR on a boosted engine at full load. Doing so will reduce the likelihood of knock, and will also keep temperatures under control.
A supercharger would have the same general principles applied to it though, in that you want to run richer on boost than you do NA.
6 psi might well be little enough boost to get away with it safely though.
Most boosted guys worrying about keeping AFRs in the 11-ish range are running, let's just say, a lot more than 6 psi
Thread Starter
Driver
Joined: Oct 2007
Posts: 191
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From: Greece
Totally agree Kurtz
But you want to be at 11-ish if you are boosted beyond 7-8 psi which is still not high boost.
On Honda Type-R with a compression ratio of the engine at 11:1 the JS Racing bolt on S/C kit which comes with a remapped ecu works at 5 psi and target AFR at 12.8.
Also the factor of bad quality gas is something that car makers take seriously and that's why the tune their ecu's to run reach as the article you attached says.
With a 100 octane residue free gasoline the perfect combustion should be at 14.7:1 according to theory.
And that's why the ecu tries to keep it at 14.7 when there is not load in the engine in order to reduce consumption.
I beleive that LEXUS mechanics have done a great job in the 4GR-FSE engine and they have given to it a 15 to 20% flexibility of AFR through the ecu.
I beleive that Steve found out this factor on his R&D and calculated that the ecu could easally handle 5 psi of boost.
In fact that's what i see for two days now.
The ecu constantly corrects the AFR and now targets for richer mixture.
Nice Japaneese software.
But you want to be at 11-ish if you are boosted beyond 7-8 psi which is still not high boost.
On Honda Type-R with a compression ratio of the engine at 11:1 the JS Racing bolt on S/C kit which comes with a remapped ecu works at 5 psi and target AFR at 12.8.
Also the factor of bad quality gas is something that car makers take seriously and that's why the tune their ecu's to run reach as the article you attached says.
With a 100 octane residue free gasoline the perfect combustion should be at 14.7:1 according to theory.
And that's why the ecu tries to keep it at 14.7 when there is not load in the engine in order to reduce consumption.
I beleive that LEXUS mechanics have done a great job in the 4GR-FSE engine and they have given to it a 15 to 20% flexibility of AFR through the ecu.
I beleive that Steve found out this factor on his R&D and calculated that the ecu could easally handle 5 psi of boost.
In fact that's what i see for two days now.
The ecu constantly corrects the AFR and now targets for richer mixture.
Nice Japaneese software.
Last edited by pepos; Oct 4, 2010 at 11:01 AM.
