right guys who knows what is actually done to a scooby oil pump to modify it when shops sell them as a modified pump what is done. i know its somthing to do with the relief valve as it sticks but what does this cause when it does and what other mods are done if any to the pump. more pressure ?????

 

I dont know the answer but its a good question and one I would also like to know.

 

the pumps are modified but not upgraded pressure wise..............

generally they are de-burred and cleaned up internally and have a 1-piece smooth relief valve fitted rather than the ridged std item

alyn

 

when the relief valve sticks you will lose oil pressure resulting in the dreaded big end knock. severe engine damage basically!!!!!!!!

 

Ours are painted crackle red

David APi

Agents for:
Simtek, the most exciting new Ecu for years
Buddy Club exhausts
Scoobysportexhausts
Eibach suspension
AP Racing brakes and clutches
And of course; the well known APi Performance Exedy organic clutch and modified oil pump.

www.apiengines.com

01926 614333

 

Seriously though :

We strip them and de-burr all surfaces, micro polish all working surfaces, adjust relief valve pressure spring to a standardised setting for oil pressure.

Mostly we use the 10mm pump later cars have a 12mm pump for the added load of the AVics oil pressure related variable valve timing.

Then:

We paint them crackle red Makes it easier to know who has one.

Never had a problem with one after that treatment

Some of the modified ones from the USA are the old 9mm pump which is WRONG

David

PS Group buy anyone ??

 

David, I take it you modify the v.1/2 92-96 EJ20G pumps too? Do you have any 'off the shelf' available for purchase? How much?

 

We sell at £125.00 + VAT outright or we do them at £75.00 + VAT exchange for another 10mm pump.

You can tell what you have now, because the casting shows a small 9 or 10 or 12 on the outer face [ oil seal side ] to the left, at the top of the pump, up by the fixing for the crank angle sensor.

If you send me back a 9mm against a 10 mm exchange - there will be a £50.00 surcharge.

David APi

 

David, just wondering you guys build a lot of engines and see a lot of blown engines im sure, do you think the realese bearing sticking is a bit of a myth and more likely down to a lose screw on the backing plate or other issues maybe ?

Would it be likely that the debre from the failure is jaming the relief valve rather then the relief valve causing the failure ?

Renno

 

Renno, The de-burring is the secret. The valve sticks, if it is going to at all, because of the rough finish everywhere.

Usually it is the debris that makes it stick, rather than the valve sticking that causes the debris.

IE - the big end failure is not caused by a dodgy pump, more usually det - overloading the upper big end shell, which fails and then spins around inside the rod. Remember, that by the time you hear the noise, the bearing has been failing. The noise is after it has failed - too late to save anything.

That is where the debris comes from.

Det can be created by several problems on a Subaru and in the case of the boxer engine it is a killer. Most other engines of our experience resist rather better.

Regular det culprits are:

Low fuel level in the tank, causing air in the fuel lines and interrupted supply.
Poor fuel Octane.
Failed maf
High intake air temp
High water temp

David APi

 

thanks for this info david i will bear that in mine when i need a pump for an engine im building at the mo so out of the 2 pumps 10 or 12 mm is the 12 mm better does it pump more oil and at a higher press ??? also have you got a tel number i can call you on for when i want to order a pump cheers jamie

 

It's under 'Location' above his Scooby avatar

 

The 12 mm has a greater flow to cope with the extra demands of the Avics But is not strictly necessary on a non Avics engine. The 12mm are also dearer, as we have no stock of them in our exchange system, other than a brand new one as an outright sale.

Stick with 10mm - it will be fine.

01926 614522 or 333

David

 

I have a scooby Avatar ? is that good? can it be tuned? how many miles per gallon does it do ?

Signed; old fart technophobe.........

 

David, do you know of a scientific reason/s why the flat-4's engine is so intolerant of det , compared to other configurations e.g. typically, in-line-4 turbo motors? Do they have really weak OEM big end bearing shells, or something ?

Aside from preventing the things you've listed, and fitting an uprated oil pump, is there anything else that can be done to the engine to alleviate/significantly delay big end bearings failing due to det?

 

<<< LOL, your Scooby avatar is your one of these..

 

Broadly anything that is interfering with the fuel quality. Breathing oil fumes makes for 2 stroke fuel - so breathe out to fresh air.

Original OEM crank bearings are selectively sized and matched at first build by Fuji. That is what the letters stamped/etched on the crank webs mean. BUT you cannot buy selective bearings from Fuji - even in Japan. None of us out here in tuning world can match a bearing to the crank like Fuji do, at first build. So we generally use original selective bearings that come with a new short motor, if we are building that way.

After that, we use tri-metal race bearings which are much more durable and will withstand a good amount of distress.

Obviously we set the bearing clearances with 'plastigauge' on the big ends. Mains you have to take pot luck, as it involves machining the block to do anything about a bad reading. By pot luck, l mean that we get them within approved tolerance, perhaps not as perfect as Fuji - but certainly not wrong.

As for why a boxer is more prone to det than a conventional upright engine I have no concrete idea that I'd express on here.

David

 

Just to add to this, my big end failure story was pretty much what David said. A big bout of detonation around the rev limit, a quiet knock started getting louder, then oil pressure dropped drastically.

So the order was: detonation shock transferred down rods > shells wrecked > debris circulated through the oil pump > debris jammed relief plunger > further damage > rods rattling up and down with pistons hitting combustion chambers > knackered engine.

Lastly, I looked into the question of what is modified in a modified oil pump and asked everyone I could find who actually made them. They all have similar mods of cleaning/deburring and doing something with the relief valve plunger - some replace with smooth, some round off the sharp edges, some shim the spring, or any combination of these operations.

 

Cheers for the heads up re the bearing info - very interesting. Are you saying that the next best bearings are your tri-metal jobs... or that they are even better than FHI's application?


Out of interest, do you know, therefore, if other manufacturers' 'boxers' e.g Porsche's venerable flat-6 (or even Ferrari's Testarossa/512TR/512TM flat-12! lol), suffer det-related big-end problems?

 

Can you recall the exact situation you were in when your det happened etc.? Or do you reckon it happened over time without your knowledge?

Were you not running a mappable ECU at the time? What mods did you have, etc, etc.?

 

Yes I can recall it very clearly - it was on a rolling road run and hit the limiter pretty violently with a lot of big knock spikes beforehand (yes it was mapped, and had never had det problems before, although it was running on 95 octane fuel with a load of octane booster in it, instead of the V-Power it had been mapped on). It was perfectly fine until then anyway. Immediately after the run it seemed OK, on the way home I started hearing a light rattle which gradually got worse and seemed to appear at certain mid revs, eventually becoming a loud rattle all the time. When I stripped the engine, there was swarf everywhere, the shells were ploughed right down to the backing layer, the crank journals were ruined, one chamber had the marks of the piston crown stamped into it where it had hit repeatedly. The piston could be rattled up and down by hand. Nice.

IMHO it was detonation rather than oil pump failure that was the primary cause of the big end knackering. The oil pump failure just made things that were already bad, worse. There WAS swarf in the relief valve, but remember the oil pressure only dropped, and temp rose, way after the first light rattles were heard. For a while all gauges were fine.

 

someone say group buy?

 

So, because there's a 'reason for everything', do you put it down to the 95 RON + octane booster cocktail not getting anywhere near the mapped V-Power's RON level of 98.6 and - coupled with the arduous rr conditions - this then brought on the devastating detonation?

 

If detonation is the biggest demon, would a knocklink or the likes be the answer and if all was well there, along with fitting a modified oil pump, should leave you with a long lasting engine or is that being a bit niave?

 

Tri-metal crank bearings are stronger than OE. But cannot easily be fitted to the crank with such close tolerances as the manufacturer [ Fuji Heavy ] can. Nothing in the afterworld can measure as closely.

6 and 2 x 3's in my opinion.

'kin rolling roads, great for diagnosis, but a very definite engine breaker in my opinion. I hate 'em. AND I was trained on them by Hartridge Clayton waaaaaaay back in the 70's, so I have a valid opinion.

You can make them say what you want them to say - good or bad...........

It is very dangerous to run a car [ Subaru more so ] hard on any other fuel than what it has been mapped for. regular + booster will not be the same ron value as V Power.

Knocklink and oil pressure are the only two extra dials you will ever find in my car. [ right now I don't have either ] Both GOOD things.

I have no knowledge or opinion about any other flat type engine.

David

 

Cheers David, awesome knowledge form 'The Deity', lol.

I agree with the dials for a turbo car - monitoring for 'knock' and 'oil pressure' are your lifelines.

David, I have an Apexi PFC mapped at 1.1bar on Esso Supreme 97 RON... but always use V-Power, as a way to definitely try to keep det bay, should things go awry...

...Now on the Commander, you can monitor knock and it records an arbitrary figure for it on the fly. So far, I've never seen it go beyond 30+ (aside form misfiring on the limiter)... I don't suppose you know what sort of figure will show if the motor is definitely detting its head off (excuse the pun)?

 

To the best of my knowledge, the A'pexi knock thing is not necessarily det but a monitoring of all engine [ + engine bay ? ] noise. It is an arbitrary figure per car and just because yours shows 30 and your mate's shows 76 does not mean that one is right and one is wrong it is just the differing noise levels between two cars. Wired in correctly an A'Pexi will flash the check engine light when detting is apparent, regardless of the reading on the hand commander.

Unfortunately, unless it has been turned off or set high it will also flash the cel for over reading on injector duty or boost regulator duty [spikes ] etc., etc.

I am sure that an A'pexi expert [ certainly not me, in that case ] will put us, me, you, straight.

David

 

Yes David, I have all 3 CEL parameters 'turned on' to monitor i.e. knock, inj duty... and, I think, airflow voltage is the other one.

I've never noticed the CEL flash rapidly for knock [GOOD!], but have seen it stay on momentarily at near the redline in either 4th or 5th - I think this is my std 380cc injectors ever so briefly maxing out (I think JGM Simon said he set it to flash when at 100% duty, rather than the default 98%).

 

Thanks David for your input, excellent info.

 

The Apexi knock reading is off factory knock sensor signal, so 'normal' knock varies from one car to another. I would expect that the bad fuel and harsh running conditions did my engine in. However, I made the decision to run it on there, and I have to face the consequences. It's just one of those things unfortunately.