drive or drived EA82 turbo ?, GO questions

[steptoe]

If you own, have owned or driven a car with the EA82T , I got a question

When driving my std boost EA82T right foot to the floor turbo in use stuff, I find there is a point about 4500rpm that the power sort of stops coming on and then some.
It is difficult to describe other than when I get to about 4500 feeling the great turbo surge, the power sort of stops, the engine does not die or miss or stumble


When I had a fuel exhaust anal iser hooked up I was too cautious to really try screwing it to see the readings as suspected HVLA over riding suspected weak valve spring was causing a miss immediately after at idle and the power mixtures started to lean out a ratioo or so, waiting for proper tune after new springs
Did/do you normally feel turbo push to redline ?

It did it on petrol and does same on LPG , so two different fuel supply systems

I do have what is thought to be lifter pump over riding a weak valve spring and that fix is awaiting arrival from japan a set of new springs BUT that has been occuring under different op conditions that I can identify with

anyone??

[fredsub]

I recall there was something odd about ~3200rpm or so, so there is this odd bump in the wide open throttle map for the fueling. But you really can't compare because mine was MAP based, not AFM.
Power keeps coming fast till about 5800rpm and maxing the fuel injector times at that point.
Only went to 8psi though.
It used a Microtech Digi2

[Gannon]

The drop in power after 4500rpm is to do with the way the engine breathes, long skinny intake manifold, cam profile, exhaust.

Its a trade-off between low end torque and high end power. The engineers behind the EA82T chose to make torque come on strong and early at 2800rpm in trade for less power up top.

If you want better top end power, get a different cam profile.

I recall there was something odd about ~3200rpm or so, so there is this odd bump in the wide open throttle map for the fueling.

I had that same dip in power at around 3100rpm and it went away when i got my injectors reconditioned. Dunno why.

I suggest you get them reconditioned and see what happens.

[AndrewT]

Sounds like a flat spot, maybe something dirty needing a clean (like injectors etc). Other EA82T owners likely also have this issue but I'd say it's more likely cause their all quite old motors and ancillary parts which need cleaning or reconditioning.

[Subafury]

mine was the same. power didnt go up any more on full boost from about 4500rpm after the initial boost kick.

[fredsub]

I suggest you get them reconditioned and see what happens.

I fairly sure cleaned injectors didn't make any difference. Its probably some quirk of engine dynamics.
Anyway its all history to me now.......

[steptoe]

If I had only been running on wet petrol and not done the injectors, but I have done them (chasing the miss in #2, now believed to be lifter pump/weak valve spring) It happens on both fuels, wetrol and LPG.

I think I found the answer watching the boost gauge instead of the road - just as it (BOG not flat spot) powerbegins the boost needle quivvers at about 6.5 psi and when the flat/bog bit goes and more GO comes on, the boost gauge then reads 8 !

Maybe it is time I learn about after market boost controllers or swap the diaphragm and look at more boost - at same tiem loook at more retard in timing to coincide with extra boost

Now this being non fiddled with i thought would never read 8 psi

I was thinking maybe the factory overboost jigger vacuum cannister mounted wth the boost light jigger on RHS front shock tower was coming in to play but definite it is deactivated as it would only effect fuel supply if running on petrol My current furel supply is LPG fed in at about 100 psi and not ecu intervention

[discopotato03]

I think your gonna find that EA82T's were all about get what torque they had reasonably soon and not too much - front drive wheelspin .
By even 80's stds the manifolds are very crude so they don't breathe in or out very well .
My experience with other 80's OEM turbo engines was that at a certain point in the rev range the manufacturer discovered that the engines detonation threshold went down and they could increase the ignition advance to boost performance .
Also in those crude engine management days the Japs would often make the AFRs go really rich (10-1 AFR) because it was in theory safe from a longevity point of view , also once a gate type AFM is fully open all the computer has to work off is throttle position and RPM signals . Crude but workable .

The std IHI turbo has a tiny turbine housing (had to be that way because of the pea shooter pathetically small header internally) so these engines are going to reach the turbine/housings choke point typically low in the engines rev range .

Chief limitations in an EA82T powered car are 1) exhaust from turbo 2) header 3) turbo 4) injectors 5) inlet manifold 6) low CR and soft cams .

The best ones had the spider inlet manifold , slightly better cams , very slightly better header - called late Vortex AWD turbo .

The "dirty emissions" countries missed out on the down pipe cat as well .

A .

[steptoe]

think I was sleep surfing the other night and bought a cheapo boost control on buy it now ebay. see how 70's technology of Impco and high octane LPG (109 RON) eliminates many posibilities such as injectors, ecu, maps, fuel pump (and causes little problems all on its own )