Ellie RX Turbos engines , the differences .

[discopotato03]

I bought my 86 L Series RX Turbo sedan a few years back from a fella in Melbourne and it was complete and in std original form .

I had an idea that this engine was pretty tired because of its indicated 250K and a lack of turbo oomph .
I had the engine compression tested and the variation was marked ie from 80 to 120 psi so basically worn out .
I made the decision to get a second hand engine and have it rebuilt , had to use this car as a daily driver to keep the K's off the Skyline .
Usually if I'm having an engine rebuilt I search to find out which was the highest performance locally available version of that engine because factory engineering is hard to beat as a base line .
As luck would have it one of the boys on the Brindabella Motorsport Club (BMSC) tipped me off that Paul from Subawreck in Adelaide had just received a damaged 1987 Vortex AWD Spider turbo car , the second one he'd had in 8 yrs so a rare find .
A quick phone call secured the engine gearbox and all auxiliaries and I arranged to have it freighted to Stewart Wilkins Motorsport at Mulgrave in NSW .
It was by pure chance that I already had a complete spider manifold transported to me from Canberra , people there are rallying an RX Turbo and had found an imported spider turbo EA82T engine . They found out that these inlet manifolds are not homologated in L RX's so couldn't use it . Owed me 250 so I sad yep bring it up to Sydney .
Just previous to this Gareth to the West of Melbourne (original CrossBred owner) told me he had a bare spider manifold and said if I paid the freight I could have it . What would you do ? This was the first one of these manifolds I had and you pretty soon work out that without fuel rails injectors regs etc they aren't much good . Then came the second complete one from Canberra and last the 3rd one on the complete Vortex engine .

Ok , the engine was striped down and found to be in very good condition because it had been rebuilt once previously . Pistons and bores were real good as was the crankshaft journals and oil pump internals .
Brand new genuine rings were sourced from Japan and good bearing shells were available locally as was the water pump .
I decided to get the piston crowns ceramic coated because these engines don't have piston oil squirters and pistons cop a hard time temp wise in turbo engines .

Gareth also had miraculously a pair of EA82T heads that were not cracked between the valve seats and these are the only ones he and I have ever seen that weren't cracked . I had AJ port these heads with most of the work going into the exhaust ports , some inlet smoothing as well .
Std Vortex cams are 14-56 56-14 which equates to 252 deg duration and 28 degrees of overlap . I looked in my Factory WSM to see if there was anything better and it turns out that the later MPFI NA cams are 16-60 60-16 meaning 256 degrees duration and 32 degrees of overlap . I though it's not a lot more buy hey it's a factory developed profile so guaranteed to fit and operate the valve train reliably .
The rot set in a little bit because the engine builder made a typo on the compression ratio calcs and said it would be 8.6 to 1 which is about what I wanted . I found this out after the engine was assembled and it was not an economic option to pull it down again . I'm going to have to live with ~ 8.1 to 1 , still better than the std 7.7 so a small gain .

Lastly the heavy std flywheel was turned to lighten it and I reckoned it was still too heavy so it went back a second time to have extra material milled off it as well . Be careful if you do this because in my case the timing marks were machined away which is a PITA . Luckily Spider Vortex engines have a scale plate that bolts on the water pump and can reference off the crank pulley .

The water pump is a bit different from the one that came out of this Vortex engine , it has pressed steel vanes which are larger than the originals and a lower number of blades .

As explained in a previous thread my Spider manifold had an aluminium adapter made and welded to the spiders plenum so it would mount a std 86 RX Turbos throttlebody and throttle position switch unit . The Vortex one is all the wrong way round and opens in the opposite direction , its TPS is unique and doesn't work properly with the 85-86 cars computer . Four plug ECU type TPS's don't have the open throttle contacts only the idle position ones . I think mine is the only 3 plug ECU spider system in existence with a 3 plug ECU type throttlebody and injection system . Had this car been a later 4 ECU plug system we would have used the spiders std throttlebody and TPS because its electrically compatible . Our mods were far simpler than converting to the later EFI system .

When the rebuilt engine went it one my Vortex headers went in with it but only because it was the best one of the three condition wise , I don't think there is any performance difference here .

I guess the exhaust behind the turbo is not really an engine mod but mine is all 2.25" with a rather large 3" bore cat behind a 3" swivel joint . We only used this size cat and joint because they were what we had at the time . The dump pipe has a conical flare from 2.25-3" (dump to front half of swivel) and same in reverse from the rear of the 3" cat to the 2.25 tail pipe . Behind the cat is a 2.25 strait through resonator and there is an oval muffler down the back with a perforated straight through gentle "S" shaped pipe through it . Very quiet and non restrictive .

Next on the to do list is a TWE type header pipe though with more appropriate sized tubes . The pending turbocharger is a hybrid and started out as a Garrett ball bearing GT2554R , I don't like the turbine or housing in these so I had GCG Turbos in Sydney swap in the higher performance GT28 NS111 76 trim turbine which is lighter/larger trim/more performance oriented .
These turbos usually don't come with a high temp iron alloy turbine housing so mine is getting the better material spec version with the extra cast in vane which blocks exhaust gas exiting the waste gates hole blasting sideways into the turbine outlets gas stream .

What I hoped to achieve out of all this is small improvements in most areas and the sum of which should make a vast improvement over a Factory L Series EA82T engine . The costs are way beyond what simply throwing an EJ20 turbo engine into it would have been but I would have had to rebuild that anyway . I always wanted my car to remain essentially an L Series platform which means having an EA82T engine in it .
The last expensive mod to this car engine wise would be a ViPEC V44 engine management system which is streets ahead of any L or classic Impreza IMO . When it allows you to use larger injectors and throw off the primitive mechanically driven distributor type ignition system you can truly tune to what parameters the engine likes best .
When it can have two sets of maps and the secondary one tuned to E85 ethanol based fuels , flick the changeover switch and pour in E85 , masses of advanced timing and almost no detonation rapidly close the gap between the humble EA82T and a std EJ20T engine . If it adds up to say 170+ horsepower in a 1060 Kg car then bouncing std Rex's should be easy , particularly if they are unsuspecting . If the E85 keeps the detonation at bay then don't need real high boost or intercooling either .

In time , A .

Nearly forgot , my RX has closer shorter gearing than standard and AWD so no lack of traction or falling off the boost curve between gears .

[Gannon]

So thats the story... very interesting.

Did you end up changing the profile of the cams i sent you, or are you using them as is?

Did you get that PM i sent you regarding intercooling?

As for engine management.... with the factory 3 plug ECU,.. its 'on boost' fuel maps are designed around volumetric efficiency and RPM only (because the AFM is ignored once the half throttle switch makes contact) . That means if you increase VE, you could run lean.

I have no hard evidence that the above is true, but from what i researched before i installed my EA82T, all the little bits of info indicated in this direction.Thats why i went for the 4 plug.

I am aware that lots of people have increased boost on 3plug systems with no ill effects, but this is because the factory tune is very rich, so you may be fine,... why you may even gain some power from the leaner mixtures

Keep us updated

[discopotato03]

No they were run as they came because they were in 95% new condition .

No that's not strictly speaking true about the open throttle switch and the vane air flow meter .
The twin throttle switches tell the computer three things , throttle closed , light load/cruise ie both switches open , high load via the second switch closed .

The airflow meter won't fully open unless under load reasonably high in the engines rev range . They can be fully opened before full load and maximum revs because the throttle is fully open and the engine speed signal from the distributor is increasing so the computer does know whats going on .
In that dirty era most turbo engines were set to run filthy rich like about 10 to1 AFR at full boost for reliability reasons , no one worried about fuel consumption when the foot was buried .

Another thing to remember is that an engines highest volumetric efficiency is at its torque peak and that's never at maximum revs - in a production car .

The old 3 plug system is crude but it can be played with to a degree , you cant really advance or retard a crank angle sensor /distributor without screwing up other things .

You also can't without spending money alter the MAF meter signals to add or remove fuel . With the vane one you simply remove the black plastic cover and relocate the nylon gear which alters the "clock springs" preload so the vane moves slightly more or less freely . Nothing like full programmable engine management but a few basic options .

Personally I won't increase the boost with a std VF2/VF4 turbo because they are too small to start with . That waste gate valve is really puny .
Such a pity we didn't get the USDM VF11 turbo , basically VF10 hot side and like a VF2/VF4 cold side in a slightly larger comp trim . Your TF035 was virtually a more modern version of that .

A .

Update ? Sniffing around for high impedance hose barb injectors of about 370cc flow rating . Most are peak and hold or low impedance types so have to see if the Vipec dealers can supply a V44 computer system with drivers to run them .
Actually I have 370cc FJ20ET injectors buried somewhere so could luck out there . Std EA82T are around 225cc aren't they ?

[Gannon]

I thought they were only 185cc when i had mine reconditioned.

[discopotato03]

Gannon the Americans at USMB have tested XT4 EA82T injectors and seem to reckon that they measure 225cc though don't know at what pressure .

The $64 question is do 3 ECU plug EA82T's use high impedance injectors and 4ECU plug ones low impedance ones ?
I seem to remember the late system having an injector dropping resistor and the earlier one not . It makes me wonder if adding the resistor means I can use low impedance squirters which would be good because larger direct fit ones are easier to get than high impedance ones .

Cheers Adrian .

[Gannon]

A quick search and came up with ...
185CC at 36 PSI, 100% duty cycle
245CC at 45 PSI, 100% duty cycle.

I didnt know there was a difference between 3 and 4 plug injectors. Maybe the 3 plug ecu has the resistors built into the ecu?

Easy way would be to test them with a multi-meter.

[discopotato03]

The original Vortex injectors were tested this evening and came to 2.8 - 2.9 ohm . The only 3 ECU plug ones I have are in my engine and didn't want to remove the %^&$ clip to test one in the dark . Will do so at first op .

Cheers Adrian .

[steptoe]

sort of believe injectors are the same as I think some of my motors have been 4 plug with 3 plug dizzy fitted injectors not swapped over. Not sure why you are after bigger injector supply as you have not really done much to require more fuel there have you?

[discopotato03]

Sorry , missed that last post .

Steptoe when you make more torque and you can maintain it further up the engines rev range you need more fuel .
In std form EA82's choke on their std exhaust and turbine housing , I reckon that's why they struggle to the red line at full throttle in the upper gears .

The middle 80's was the dark ages with factory EFI and for computer/injector driver reasons they usually only used enough injector to reliably get the job done for the std power output .

Once you change to sequentially fired injection the injectors only get one opportunity per two revolution cycle (four stroke cycle is two crank revolutions or 720 degrees) so they have to inject enough fuel for each cylinder to achieve its peak power potential .
With batch fire injection the injectors all fire twice per cycle or once every revolution with total disregard of whether the inlet valves are open or closed . So because the injectors get two bites at the cherry they don't need to be so big .
EA82 MPFI systems I believe do two plus two batch fire which is why the injector wires from each bank (head) join into one in the loom and branch back into two before entering the computer box .
Also with sequential injection you need a reference pulse once per 720 degree cycle so the system can time the injector (usually to close) at the most opportune time in the cycle . The reference pulse normally comes from a cam angle sensor (CAS) because cams turn at half crank speed meaning for every complete revolution of the camshaft the crank turns twice .
Distributors have to turn at half crank revs as well so they generally have 2 to 1 reduction gearing driven off the crankshaft or 1 to 1 gearing off the camshaft because its turning at the required speed anyway - EA82's are like this .

For anyone wanting to use aftermarket engine management computers the later EA82 optical CAS/distributor is a god send , very simple system requiring two photo diodes and pickups and a transister (high speed switch) to control the coil .
Computers with enough processing power (speed) can read the 360 outer slots in the disc for very accurate detection of engine acceleration/deceleration and the four inner slots tell the computer in order which is the next cylinder to approach top dead center on its compression stroke .

Anyway the bottom line is that I have 370cc hose tail injectors from my old Nissan FJ20 (2L) turbo engine and it used an almost identical CAS distributor system and sequential injection to develop ~ 205 Hp in 1984 . They were a twin cam 16 valve engine with big ports and valves and very easy to get 400 out of with a larger turbo and injectors .

Cheers A .