VR4 engine strength?

[evonut270]

how strong is the stock vr4 lump in terms of max boost/torque/power output.?

[Turbo_Steve]

Sorry dude, but you're going to need to do a lot of reading to find that one out.

Nobody seems to have destroyed their rings with boost yet (and some are running a GT35R or a pair of TD05s)

Turbos are the limitation, not the engine on the std car..as are the injectors.


Torque seems to be limited by the drivetrain - It's an Evo 4 rear diff and all that entails.
The autobox will take a lot of abuse, it seems, if correctly serviced.


And, if you're an uber-mapper, then you could remap the TCU and make a lot of money of everyone desperate for more fuel economy and better power delivery, especially in Tip.



Can you post up some specs on your E2, please......trying to select components for my build.

[bradc]

There are 3 cars around the 400-450hp range on stock internals, mine included with no problems at all.

[djb160]

RUn a search for users "Valmes" and "Gowf" I think they've run the most high powered engines off the top of my head.

[evonut270]

Sorry dude, but you're going to need to do a lot of reading to find that one out.

Nobody seems to have destroyed their rings with boost yet (and some are running a GT35R or a pair of TD05s)

Turbos are the limitation, not the engine on the std car..as are the injectors.


Torque seems to be limited by the drivetrain - It's an Evo 4 rear diff and all that entails.
The autobox will take a lot of abuse, it seems, if correctly serviced.


And, if you're an uber-mapper, then you could remap the TCU and make a lot of money of everyone desperate for more fuel economy and better power delivery, especially in Tip.



Can you post up some specs on your E2, please......trying to select components for my build.
Hi steve, ok I gather the engine is pretty strong by all accounts I just wanted to see how far some have pushed on stock internal. As for the evo4 rear diff it seems to manage abuse quite well having seen quite a few taking well over 400/400.as for mapping yeah I have heard they are quite thirsty pretty similar to evos in that respect iv mapped alot of evos now and some are getting 270-300 miles to a tank on the motorway. Iv not had the chance to map a legnum or vr4 yet but from what I've seen fuel and ignition tables have alot of room for Adjustment. So what boost do most run the stock td03s at?

[aboo]

With what I'v seen on here 1bar is about the max before we start getting fuel cut.

[evonut270]

With what I'v seen on here 1bar is about the max before we start getting fuel cut.
So is that the limiting factor with most legnum/vr4s is the mapping?If so with some help I can read some ecus to get definition files made up so I can get these things tuned

[aboo]

Seems to be.

[Nick Mann]

The first limit is fuel cut, IMO. Once you get round that, turbos and injectors will stop power before the engine itself has issues. I have heard of a few engines with bottom end bearing issues, but I think two of those were running stock power. The only catastrophic engine failures I know of after significant tuning also included another eyebrow raising factor - NOS/FCD/Raised rev limit etc.

My car is running 367 lb/ft and I have killed 2 auto boxes and one rear diff so far. Driveline can potentially start showing issues IMO.

If someone could offer mapping of the stock ECU to raise fuel cut and better control AFRs, it could open up the 350/375 bhp territory quite quickly I think. Supporting mods could be as small as a fuel pump/fpr plus exhaust. The auto box might struggle with this more than the manuals - it seems a few people have had torque converter slippage in the low 300's.

[evonut270]

The first limit is fuel cut, IMO. Once you get round that, turbos and injectors will stop power before the engine itself has issues. I have heard of a few engines with bottom end bearing issues, but I think two of those were running stock power. The only catastrophic engine failures I know of after significant tuning also included another eyebrow raising factor - NOS/FCD/Raised rev limit etc.

My car is running 367 lb/ft and I have killed 2 auto boxes and one rear diff so far. Driveline can potentially start showing issues IMO.

If someone could offer mapping of the stock ECU to raise fuel cut and better control AFRs, it could open up the 350/375 bhp territory quite quickly I think. Supporting mods could be as small as a fuel pump/fpr plus exhaust. The auto box might struggle with this more than the manuals - it seems a few people have had torque converter slippage in the low 300's.first off ill need some rom images from diffferent models with the 7202 and 7203 processors to work with i only have 4 maybe 5 at the moment but the more i get the easier it will be to offer mapping.

[Turbo_Steve]

The map is the first limit, then the turbos, then the injectors.


Evo 4 diffs at 400/400 just don't last that long if you like to launch - neither do VR4s.

And if you think the Evos are thirsty, then you are going to get a real shock with the VR4s.

My Evo was pushing 315bhp or so, and driven hard would return 15mpg or so. Driven gently it'd return 30mpg.

Driven (very) gently, my VR4 will return as much as 24mpg. Driven hard it's 15mpg all the way. It's making less than 300bhp.

So there is scope for leaning out the open loop fuel maps, as well as trimming the timing. I've also been looking at TPS delta enrichment and seen that some gains could be made there by maining a slightly richer map at intermediate load points (i.e. as the turbos start to spool) and reducing TPS enrichment. It's not dreadful, but it seems to think that every time you touch the acclerator, you're going to make epic amounts of boost. It's not enough to bog the car, but enough to dull the response a little and to use a lot of fuel.

Likewise, many people are running VTA dump valves. This causes the standard over-fuelling problems (bogging, possible flamage, hesitations) as well as using a significant amount more fuel: 2 - 3 mpg!

From the little research myself and a few others (Kev, Miller) have done, the TCU leaves HUGE scope for improvement - to the best of my knowledge the VR4 was the first adopter of the INVECSII gearbox, and as such has a seperate TCU (unlike later Mitsis which seem to integrate gearbox control into the ECU).

The contrast in behaviour is marked: whilst the later mechanicals appear to be almost identical, the later models using this gearbox returned significantly improved mpg, less transmission loss and usually more positive shifts (at least in tip).

However, Kev (steelie) is the only person to have opened the TCU for a look at the processor, and it's a 7201, which we don't believe is programmable in situ.

[Nick Mann]

I'm interested in learning more about flashing of the ECU. I have a late 98 car with a plastic cased ecu - so I think it will be the 7202 ECU. If I ever work out what I need to communicate properly, I'll download the base image before messing. TBH, the only messing I'd do to start with is raising fuel cut - that's limiting my boost at the moment.

[evonut270]

I'm interested in learning more about flashing of the ECU. I have a late 98 car with a plastic cased ecu - so I think it will be the 7202 ECU. If I ever work out what I need to communicate properly, I'll download the base image before messing. TBH, the only messing I'd do to start with is raising fuel cut - that's limiting my boost at the moment.Contact GBenterprises(grant) he is from your neck of he woods tell him I sent you. He can supply the cable if you want to buy it or I you speak nicely to him he may read it for you. Be sure and check the ecu board for the processor type before trying a read

[evonut270]

The map is the first limit, then the turbos, then the injectors.


Evo 4 diffs at 400/400 just don't last that long if you like to launch - neither do VR4s.

And if you think the Evos are thirsty, then you are going to get a real shock with the VR4s.

My Evo was pushing 315bhp or so, and driven hard would return 15mpg or so. Driven gently it'd return 30mpg.

Driven (very) gently, my VR4 will return as much as 24mpg. Driven hard it's 15mpg all the way. It's making less than 300bhp.

So there is scope for leaning out the open loop fuel maps, as well as trimming the timing. I've also been looking at TPS delta enrichment and seen that some gains could be made there by maining a slightly richer map at intermediate load points (i.e. as the turbos start to spool) and reducing TPS enrichment. It's not dreadful, but it seems to think that every time you touch the acclerator, you're going to make epic amounts of boost. It's not enough to bog the car, but enough to dull the response a little and to use a lot of fuel.

Likewise, many people are running VTA dump valves. This causes the standard over-fuelling problems (bogging, possible flamage, hesitations) as well as using a significant amount more fuel: 2 - 3 mpg!

From the little research myself and a few others (Kev, Miller) have done, the TCU leaves HUGE scope for improvement - to the best of my knowledge the VR4 was the first adopter of the INVECSII gearbox, and as such has a seperate TCU (unlike later Mitsis which seem to integrate gearbox control into the ECU).

The contrast in behaviour is marked: whilst the later mechanicals appear to be almost identical, the later models using this gearbox returned significantly improved mpg, less transmission loss and usually more positive shifts (at least in tip).

However, Kev (steelie) is the only person to have opened the TCU for a look at the processor, and it's a 7201, which we don't believe is programmable in situ.Afaik I don't know of any dissassembly work being carried out on the trans ecu but I will dig around to find out more. Getting the open loop crossover points adjusted is a very good way of making the car more mpg friendly. I'm looking for more of the crossover points at the minute. Is here anywhere that has ecuflash XMLs available for the legnums/galants

[Kenneth]

Has anyone started the VR-4 engine ECU disassembly? If so, I would be very interested in either helping out, or finding out the correct disassembly steps. In the mean time, I guess ill try work them out myself :P

As for limiting factors, we have had evidence of the standard fuel pump starting to cause lean running at just over 190kW (all wheels), which I have also managed with a standard ECU but with an aftermarket fuel pump.
I would put it out there that you want to change the fuel pump #1, then mapping.

[Kenneth]

Though in saying that, I am sure you can get some good improvements below 190kW, but if you are planning on tuning to above that, fuel pump is critical

[Nutter_John]

When I was doing the 7201 tuning last month we had to pull one off the dyno cos the fuel pump was not pushing enough so deffo agree the fuel pump is number one mod

[aboo]

I found this out yesterday at the RR. I'm going to have to change the pump as my car was running lean at the end of the graph.

[evonut270]

Has anyone started the VR-4 engine ECU disassembly? If so, I would be very interested in either helping out, or finding out the correct disassembly steps. In the mean time, I guess ill try work them out myself :P

As for limiting factors, we have had evidence of the standard fuel pump starting to cause lean running at just over 190kW (all wheels), which I have also managed with a standard ECU but with an aftermarket fuel pump.
I would put it out there that you want to change the fuel pump #1, then mapping.yes there is a fair bit of dissassembly done already

[Kenneth]

Never mind, looks like I found it using the internet search thinggy :P /haz