renault 5 GT TURBO Megajolt????

[mark 5t]

Hello:

I`am thinking of buying a megajolt for my Renault 5 GT TURBO.
the specs of my engine are:
1400cc
4cilinder
uprated turbo running 21,75 PSI boost
uprated head gasket
special low compression pistons
uprated cam
uprated IC
external oil cooler including thermostat
carb from a lancia delta 1600cc turbo twin port (original carb is one port)

i drove with the original compressio pistons the same boost but then my
cilinder liners bursted.
car had mesured om a test bench 162,2 wheel horsepower. and 247Nm.
now I have new ones and low compression pistons.

I`am scared of detonation so I am currently running less boost until I have
another ignition.
the original renault ignition ECU has a nock sensor.
is it possibele to connect this to the megajolt?
this because my electronic knowledge is not so good.
can the megajolt MAP sensor handele mij 21,75 PSI boost?
are ther maps avaylebale for this kind of engine to start with?
and is it difficult to programm the ignitiom myself?

see the link below for my topic in duth on a renault forum.
http://www.renault-tuning.com/viewtopic ... highlight=

greetings and many thanks from holland. Mark.

[brentp]

Hello Mark,

The MAP sensor on-board measures up to 250KPa, which is approximately 21.3 PSI of boost at sea level.

The Megajolt does not have an input directly for a knock sensor. However, it is possible to connect an external knock sensor processor to the AUX input of the Megajolt and have it adjust ignition timing based on the amount of knock.

We are not familiar with the renault knock sensing system; if it is just the sensor then an amplifier/filter circuit would be needed between the sensor and the MJLJ.

This is a discussion/work in progress. Please see the discussion here:
http://www.autosportlabs.org/viewtopic.php?t=1858

The Megajolt has a built-in "soft" rev limiter. An optional rev limiter can be fitted.

See here:
http://www.autosportlabs.com/hard-limit ... -p-35.html

The "factory map" that comes with the unit is a generic "safe" map designed for turbocharged engines. It is the same MAP I use for our turbocharged toyota 4AG motor.

See our other ignition maps here:
http://www.autosportlabs.org/viewforum.php?f=15

there are a number of turbocharged maps for engines that may be similar to yours.

The configuration software offers the ability to interactively tune the controller while the engine is running, using a 3D MAP editor and the data logging capabilities. see:
http://www.autosportlabs.net/MJLJ_V4_Op ... Controller

The best results have been obtained by running the engine on a "rolling road" / Dyno and tuning for the best balance of performance vs. reliability.

Best Regards,

[mark 5t]

ok so i have a problem with the MAP sensor.
it cant handele my boost.
is there another MAP sensor availabale?

[Midas]

ok so i have a problem with the MAP sensor.
it cant handele my boost.
is there another MAP sensor availabale?

Is it possible to reduce the boost a little?

[DannyP]

Maybe this will help?

http://www.cbperformance.com/catalog.asp?ProductID=333

I am not sure of compatibility, but there has to be a sensor that can be made to work. Even if the sensor has to mounted externally, I am sure something could be done to make it handle your level of boost.

[brentp]

Hello,

if the max boost you will ever see is 21.75 PSI, then the included on-board map sensor will work for you, as there is only a 0.45 PSI difference between the maximum the sensor will read and the max boost your turbo will produce.

The reason why it is not a problem because you will probably be setting an ignition advance on the last Load bin of the ignition map for max boost. For example, anything 20+ PSI may be set to 16 degrees BTDC.

Regards,

[mark 5t]

thanks!
boost wil not be reduced but I understand your way of thinking and you have convinced me
that this will work.

maybe in the future the boost will rise up to 26.10 PSI with another turbo than I have a problem I think??


now the only thing I have to sort out is the signal what the original renault
knock sensor sends out to the ECU.

good Forum here with super help!!
greetings mark

[Alex B]

You may be in need of a 3 bar MAP sensor. Take a look at Saabforum.nl in the tuning+turbo section or put in a search for MAP sensor. Converting to a 3 bar MAP sensor has implications on the software side of things. The 5 volts that are normally used for sensing between 0 bar and the maximum pressure the MAP sensor handles is now used over a larger pressure range. Brent, can the MJ software deal with this (I intended to put a question mark here but my keyboard is somehow off key).

Alex

[brentp]

Yes, if you raise boost pressure to 26 PSI it will be better to change the MAP sensor so you can set ignition advance in that range.

On way to do this is to feed the signal from an external MAP sensor into the unit as if it was a throttle position sensor, and calibrate it accordingly. The +5v power supply for the map sensor can be sourced from the MJLJ's VRef output.

[mark 5t]

20 december my car goes on a dyno bench for adjustments and Horse Power measurment.
For this i am going to put my original ignition 3 degr later over the whole range and see what happens than.
if it is not a good result then i am going to think about buying this.

2 things that keep me back are the MAP sensor and the Knock detection.
if this is sorted out good than there is a huge market for selling these things
in the renault 5 GT Turbo world and forums!

[Hiperformance71]

20 december my car goes on a dyno bench for adjustments and Horse Power measurment.
For this i am going to put my original ignition 3 degr later over the whole range and see what happens than.
if it is not a good result then i am going to think about buying this.

2 things that keep me back are the MAP sensor and the Knock detection.
if this is sorted out good than there is a huge market for selling these things
in the renault 5 GT Turbo world and forums!

Hello Mark, Hello to all,

I had installed the MJLJ in 2 R5 GT turbos and i confirm, this is a GOOD UPRGRADE for the little french rocket! The power response if very superior compared to the stock coil unit (wich includes the "ignition ecu" with a pressure sensor but designed for only 0,75 bar of boost). Well, the MJLJ can made a big difference, and not necessary you need a knock sensing, if do you made the ignition map on the dyno, and check the AFR of the engine when is on the dyno, you can made a good job. My installations are fuel injected too, with an old BOSCH system (fiat UNO TURBO) and works very well respect the little carb. With a boost of 1.3-1.4 bars we have reached the 200 hp in an OLD engine without too much compression on the cylinders, the MJLJ was the difference. Sure, if you can measure more pressure, you can go over, but at this point we need to use an external MAP sensor, a 300Kpa unit for example connected in the TPS wiring, then we need to write the configuration of the sensor in the TPS configuration, this is a little tricky but it is possible, but the big, problem, is HOW we recognize the right point of the new boost in the configurator? Is difficult to me to explain, i will try:

Actually, if we use a MAP based MJLJ, we need to configure to use the MAP readings in the sw, it read the absolute pressure from 0 to 255Kpa.
If we use an external MAP connected instead of the TPS, and configure the sistem to the new values in the table (volts-bits) we can only say:

0 Volts = 0 bit = 0 kpa =>visualized in the CONFIGURATOR= 0 kpa
2.5 Volts = 128 bits= 128 kpa =>at this point, using a 300Kpa MAP is say: 150kpa but the sistem display the 128 value.
5.0 Volts = 255 bits= 255 Kpa =>the real pressure is 300kpa but the sw display 255kpa!!

the whole scale is shifted up a bit, for a reasonable use, we have 2 possibilities:

1. Creates your own scale in a table of conversion, and look on it every moment to know the right pressure value and the "vsualized value".
2. If Brent can make a custom version of the sw to display custom values on the 0-255 scale, if we have a value of 255 this means 300kpa in the display. But this is a big upgrade, and i don't think is easy to make.

If you decide to try the MJLJ, i can help you to map the car, i can send to you base maps.


Cheers,