Lowering CR on factory computer

[stidnam]

Just a quickie can I safely adapt the ecu, sensors, and injectors off a 3sgte with 9.0:1 CR onto a 3sgte with 8.8:1 CR or will there be issues? The only things that will be different are the CR of the pistons, the intake manifold being somewhat smaller and the turbo manifold being different.

I can't see that there would be an issue but it pays to double check these things.

[jonathan yee]

are you wanting to put the stock ecu from a gen2 to gen3?(gen2 has 9:1, gen3 8.8:!) BAD idea

people often upgrade the ecu's to the next gen, ie gen1 upgrade to gen2 and gen2 go to gen3 but never back the other way.


there are a few on the mr2 forums with gen2 motors running gen3 ecu's and sensors with sucsess.

you'd be stup[id to fit a gen2 ecu to a gen3, gen3 ecu is much better, doesnt require the ghey AFM and has high fuel cut and boost maps to 18psi.

[stidnam]

Nope the plan is to use Caldina ecu on a gen2 3sge with gen2 3sgte rods & pistons. The bastion of all truth (wikipedia) gives the gen2 3sgte as 8.8:1 and the caldina 3sgte as 9.0:1

[oldcorollas]

unless cams are wildly different, shoudl work to a fair degree...
0.2CR is pretty small in the scheme of things,and the ECU's are tuned safe.. so 0.2CR less would be saferer

heck, cars work with mechanical advance dizzies and carbies...

[jonathan yee]

ah, damn your right. sorry, gen3 has 8.5. got myself all confused. gen1 has 8.5 and gen2 8.8.

in that case you should be fine. if people run gen3 8.5cr ecu's on gen2 8.8 then i don't see why gen4 9:1 won't work.

so your building/have a gen2 NA with turbo rods and pistons. nice long torque manifold. i wanted to do this with a 5s bottom end and small t28 turbo for bottom end, thought it'd make an awesome daily/motokhana machine(in an sw20)

[RONA]

You planning on running a Caldina head/COP, CAS setup too otherwise I can't see it working too well. The pinout is completely different to the Gen 3/2 ecus. Steve is running his Caldina with an ST205 bottom end so lower comp and hasn't had any issues.

[3sgte]

Injector resistance and flow rate is the same?

(Or are you using all the gen4 hardware?)
What are you doing for the oil pump/head? (Where the crank sensor/cam sensor are located?)

[jonathan yee]

ah, yeh. you won't be able to retro fit the crank or cam angle sensors required to run the gen4 ecu. you need the late model 5s oil pump and either modify or use the gen4 intake cam and somehow fit the CAS into the side of the head which i don't see you doin.

the gen4 inj's would prob fit the gen2 NA head, both top feed inj's.

running gen3 ecu would be easier. only need the MAT, IAT, IGN module, a 3bar MAP sensor, some 550 topfeed low imp inj's.

how you gonna trigger ACIS?

[stidnam]

Well the plan is bit interesting and I'm sure you'll say why but meh like all great projects you build round what you have. The plan as I mentioned is to fit ALL the caldina electical stuff over (that means injectors, coils, sensors etc). I am the pricing sensors, injectors etc to complete the setup. The position for the crank sensor on the 5sfe oil pump is different to the caldina which is at the 6 oclock position but I have a plan to fix that. Was going to go megaquirt with what I have but decided that I can't be bothered tuning it and by the time I've bought the megasquirt and wideband it is likely to be just as cheap to get the factory gear.

Sensors shouldn't be an issue to fit up expect for the cam sensor. I've looked in the head and there isn't enough space to bore a hole in the side of the head and fit the sensor and trigger arm so the plan is to usethe shaft of the dissy and make a slimline housing to fit the trigger arm and sensor.

Wont need to trigger ACIS as I wont be using the gen2 3sge manifold. Instead I have a rwd 3sfe intake manifold which will fit with an adapter plate which shouldn't be too hard to make.

[oldcorollas]

bah,. go the megasquirt

[jonathan yee]

still be easier yet to fit gen3 ecu i reckon or is dizzy too close to firewall? caldina ecu has rev limits quite low from memory.....

[RONA]

Caldina rev limiter is 7000rpm.

[stidnam]

I already have a spare caldina ecu so going to st205 ecu would mean I'd need to buy it as opposed to free. I was seriously tempted to go megasquirt and almost bought one this week but considering that this setup is going to be used in a rally basher I don't have the time or motivation to tune it if I can just fit factory stuff and then go for a slide. It's also unregistered so I couldn't exactly hit the roads and spend time doing the tune.

I'm going to fit gen1 3sge cam covers to the head so I think the caldina coils will look quite neat inbetween the cam covers.

[oldcorollas]

yeah, stock sounds easier for that can't be that hard to sort out the rpm pickups

[beerhead]

CR won't be a problem, the ecu uses VE tables so more vacuum, more fuel before the motor is boosting.

You need a late 5SFE/3SFE oil pump, caldina or beams crank pulley with machined trigger teeth (FE has 1 extra cam gear tooth and will run out of phase) The only tricky sensor to replicate is the CAM reset trigger, as the head doesn't have the sensor built in. Have a look at my 3SGE build thread and you'll see how I made a cam reset trigger in the top of the cam cover. It might work ok if you could just wire the dizzy's cam reset trigger to the ecu I guess.

I'd personally buy an ST205 ECU, sell the caldina one and save your troubles. By the time you buy all the bits to make the caldina ecu work you'll end up spending more than what the ECU that will just work without any headaches goes for. I tried for over a year to get a second hand crank trigger pulley to suit my motor, and never found one, leaving a brand new Toyota one for $200 as the only option, which is what I sold my ST205 JDM ecu for last year...