Legnum 1.8GDI 4WD Auto is too slow!

[Grinder]

Some of you may remember my main car is a Skyline and my wife drives the Legnum 1.8GDI around with the baby (soon to be babies!) in the back.

Only thing is the other day she took the Skyline out for a night out and she is feeling a bit short changed in the vehicular department.

The Legnum is a big car, and with 4 wheel drive and the automatic, the 130 bhp just doesn't shift too well.

Let me just say this is just thinking out loud at the moment and I'm just wondering if there is an 'easy' way to give the car more poke.

I'm not wanting to squeeze 8 or 10 extra bhp using an after-market air filter or iridium spark plugs...what I am wondering is can I swap in a V6 engine or something without too many problems ?

I don't want to do any cutting or welding, just looking for a straight swap, keeping the existing gearbox & 4WD.

If this is not possible, has anyone considered nitrous in the 1.8 ?

In either case, do the more powerful Legnum models have different suspension or brakes ?

THANKS FOR ANY HELP GUYS - just hoping for some brainstorming at the mo.

[enigma]

Some of you may remember my main car is a Skyline and my wife drives the Legnum 1.8GDI around with the baby (soon to be babies!) in the back.

Only thing is the other day she took the Skyline out for a night out and she is feeling a bit short changed in the vehicular department.

The Legnum is a big car, and with 4 wheel drive and the automatic, the 130 bhp just doesn't shift too well.

Let me just say this is just thinking out loud at the moment and I'm just wondering if there is an 'easy' way to give the car more poke.

I'm not wanting to squeeze 8 or 10 extra bhp using an after-market air filter or iridium spark plugs...what I am wondering is can I swap in a V6 engine or something without too many problems ?

I don't want to do any cutting or welding, just looking for a straight swap, keeping the existing gearbox & 4WD.

If this is not possible, has anyone considered nitrous in the 1.8 ?

In either case, do the more powerful Legnum models have different suspension or brakes ?

THANKS FOR ANY HELP GUYS - just hoping for some brainstorming at the mo.

Nitrous will work well, but it wont be a permanent mod.....just the odd blast here and here! It is huge fun and you could well get 4 mins of grin inducing fun from a bottle (about £40 to refill) Initial cost is low, but insurance and refills will criple you! Best off going for something more traditional or even a turbo kit! :D

[Nick VR4]

I have a feeling the V6 has different mounting points to a V4 ???? could be wrong though :rolleyes:

NOS now thats a point although could get ££££

[Grinder]

Is there a turbo kit for my mota?

Edited to say: other points taken on board - thanks.

[Kenneth]

Is there a turbo kit for my mota?

Edited to say: other points taken on board - thanks.

Maybe... there are 1.8GDIs with turbos out there, but you couldnt do a bolt on kit. The reason is that the Naturally asperated GDI uses a compression ratio of something about 12.5:1

So you would have to do something to reduce that compression befor you force fed the engine.

You could swap with a 1.8turbo, I think they run about 10:1 or something high... GDI is awsomely suited to turbo applications, pity about the hassle with the engines. (they screw up at high mileage and have so much gear on them they arnt worth playing around with... thats my experiance anyways)

You would probably be better just trading in for a 2.5... turbo or non turbo, your choice.

I had a 1.8GDI galant. I loved the shape and looks, but its performance left me less than happy. Had it for 18months, then got a VR4.

[enigma]

Maybe... there are 1.8GDIs with turbos out there, but you couldnt do a bolt on kit. The reason is that the Naturally asperated GDI uses a compression ratio of something about 12.5:1

So you would have to do something to reduce that compression befor you force fed the engine.


You could do a custom turbo kit including lowering the compression for not a huge amount of cash.....but it would be a lot of work...........I would be tempted though! :D

[Kenneth]

You could do a custom turbo kit including lowering the compression for not a huge amount of cash.....but it would be a lot of work...........I would be tempted though! :D

I'm curious as to what parts, configuration etc you think you would need to convert it to a turbo... and what sort of boost you would run.

The reason being is that I have done a lot of research into the GDI engines (I had one that didn't work particularly well and no one could seem to fix it. )
and while I think they would be a cool platform for building a serious performance engine, I don't think you can do so cheaply.

[enigma]

1 secondhand turbo £100
Custom manifold and piping £200
Piggyback ECU £300
Intercooler £50
Intercooler piping £50
Rising rate fuel pressure regulator £80
Thick copper head gasket to lower compression £100

plus a bit of time and patience.

It would have to be fairly low boost like 0.5 bar max but it would make a huge difference!

[Kenneth]

1 secondhand turbo £100
Custom manifold and piping £200
Piggyback ECU £300
Intercooler £50
Intercooler piping £50
Rising rate fuel pressure regulator £80
Thick copper head gasket to lower compression £100

plus a bit of time and patience.

It would have to be fairly low boost like 0.5 bar max but it would make a huge difference!

There are 2 areas where I can see things getting very complicated! well its esentially one area, but 2 parts to it... Fuel delivery.

1) GDI injects (according to mitsubishi documentation) at 50MPa (500bar, 7000 odd PSI) although I have read other documentation that says its old 5MPa, thats still 700PSI.
The GDI engine has 2 fuel pumps, one is mounted on the engine right by the fuel rail (for obvious reasons). The chances of a FPR being of any use are in my opinion non existant.

2) The GDI has 3 injection modes, ultra lean, mixed mode and superior output.
ultra lean runs something like 40:1 AFR, and injects in the late stages of the compression stroke. If you were to supply extra fuel that the ECU didnt know about, you could cause detonation.

mixed mode injects a squirt in the induction stroke. this is used to cool the intake charge and cylinder, but isnt enough to ignite easily. the rest is injected under compression. Again if you play with the fuel, you are asking for trouble

Superior output injects on the induction stroke, like a conventional engine. This mode is used above a certian RPM and under high load (or above 120KM/h )

So if you did manage to supply the extra fuel, you have to deal with the fuel supply under all these conditions without destroying the engine. and dont forget that the ECU switches between modes whenever it feels its the right thing to do.

Now if you had a programmable ECU, you would be able to inject in superior output mode all the time, and you could probably get away without any extra fuel requirements as the GDI injectors can deliver a lot of fuel at low duty cycles. so long as your ECU doesnt mind having a max duty cycle of 50%. and even at 50% you are still injecting under compression.

of course, you could just get a computer out a 1.8GDI turbo, but there is probably other gear you need, which probably wont be cheap.

For the risk and hassle involved, I feel it would be easier to eithier get a bigger car or just replace the engine.


I dont want to sound like I am saying it cant be done, I would love the opportunity to mess about with a GDI engine... I just dont think you can do it cheaply. You wouldn't want it to be in the car you rely on for transport eithier.

[Grinder]

This is all good stuff.

Kenneth, on medium duty I'm burning fuel just to cool the cyclinder & charge - yikes - no wonder it uses so much fuel. Sounds like water injection would have achieved that for less money.

Its certainly got me thinking about the performance of the car. I was driving it today, and its actually not too bad higher up the revs. It might just be cheapest option is to thrash the beast until it dies :D As long as I get 3 years out of it, it will have paid for itself.

(stupid FM radio has stopped working - now thats another subject!)

[enigma]

There is nothing that says you cant run an extra injector! But to be honest if the fuel delivery pressure is that high the amount of control that the ECU has must be phenomenal! So it must therefore be controlable. I still dont think getting an extra 50BHP would be hard.

[enigma]

Looks like you can get a factory bolt on kit from Canada!

Turbo (http://forums.evolutionm.net/showthread.php?t=93701&page=3)

[Grinder]

Wow what a breakthrough - nice one BDA.

I might have to post on there and get a part number - I know its a long-shot but you never know.

CA$5200 is £2500 - not exactly cheap but costs nothing to enquire :-D .

[Grinder]

Just looking on the Japanese website where I bought it, and it might be cheaper to bring over a Viento V6 or VR4. See below nice 1997 V6 going for half-million Yen - about £2500, but after import costs about £5000 probably.

[Kenneth]

Looks like you can get a factory bolt on kit from Canada!

Turbo (http://forums.evolutionm.net/showthread.php?t=93701&page=3)

you mean this?

"just to let you know you can order a factory installed and warrentied turbo kit from mitsubithi, it is around 6500 CDN installed 5200 CDN UNinstalled.... comes with ECU, INjectors, everyhting runs 6psi."

It's about what I would expect... mitsi just give you the things they put on the turbo 1.8 GDI. Not what I would call cheap though.

The ECU is the important part.

I had thought of adding an aditional injector, but you would have to ensure that it only fired (and the turbo spooled) when you were running in superior output mode, otherwise you would interfere with the methods it uses to control detonation. Not worth the risk IMO.

Grinder:
The fuel consumption problem is not caused by that... there are a combination of things, one is probably the fuel quality. Something to do with the sulfer content.
My 1.8 GDI was doing max 8.5Km/L. which its utter crap for a 1.8.

The mixed mode (light duty) squirts a small amount of petrol in the induction stroke, to cool the charge and cylinder. it then injects the rest on the compression stroke.
If you ask me, thats pretty damn good injection control.

despite injecting twice for one cycle, it still runs about 20:1 AFR!
This is the reason for the initial squirt, cool things enough to run a higher AFR.
it also uses a lot of EGR to keep things cool... but I wont go into that here.

[Archie]

Just found this thread and I'm interested in the whole GDI thing. Why is it so bad? Why did Mitsubishi think it would be a good idea. And now Porsche have it right? What have they done differently?

All questions for lazy days

[bradc]

Lots of cars have direct injection now, but Mitsi were the first to really do it. My 98 GDI that I bought in 03 was a very nice car and I had exceptional fuel economy from it on 98 octane.

The main problem is that over here most people run 91 octane in them which they simply aren't designed for. As part of the design they run a large amount of EGR which cokes up the intake manifold, throttle, and performance suffers greatly.

A 1.8 GDI engine in good condition is a perfectly fine engine that gets exceptional fuel economy, around 7L/100km is acheivable and on the early 1.8's they make 110kw which isn't bad at all from a 1.8 n/a. They make around 100nm of torque per litre which is still quite good too. The rev to 7000rpm and are quite smooth the whole way up to the limit.

The 2.4 GDI's are something I'm less fond of. They only rev to 6000rpm and make a huge amount of noise and vibration above about 4000rpm. They produce a reasonable level of torque down low, but you won't want to rev them above 4000rpm for very long at all! A good one will get 8l/100km, but they often do a lot worse than that. They also require 98 octane.

Compared to the V6 2.5 I would take the V6 every day. You will use slightly more petrol compared to a good 2.4, but you only need to use 91 octane and the V6 simply just works. They always just work and never have any problems! They also make about 10kw more and rev happily all the way to 7000rpm.

You can also get the V6's with a manual gearbox, which is something you just can't get on a 2.4 JDM. In the european market you can get manual 2.4's though.

The only possible reason why you may consider a 2.4 gdi over the v6 2.5 is that the auto ones came with a 5 speed box, whereas the v6 only came with a 4 speed with widely spaced ratios which is a bit unfortunate.