Hi All,

I have recently purchased a 95 type RA Jap purely for track use. Blew it's big ends first time out. Have no clue why it did it, ran on V power running a standard Z5 ECU. No major engine mods really to her, mainly suspension. She has an induction kit and a boost controller but only ran at 1.1 bar this time. I did gag her revs though and feel oil was the main problem. I know I should really be getting her checked and mapped if necessary but want to try to understand more about the mechanics of things a little. I've had a second hand lump put in while the old one is fixed, as a spare hopefully.

My plan is this... I am going to fit a knocklink, oil pressure gauge, and oil temp gauge and take her round again but this time take it easy, build it up and watch what's going on. I'm assuming if there is a set up problem I should see excessive knock, temp or pressure probs early enough to stop and get her seen. Now for the questions.

1) Am I mad doing this or do you think this will be safe?

2) I read a lot about what causes big end failure and it's not an exact science, det being a favourite one. Am I correct in assuming that a excessive oil temps and engine temps can cause det alone?

3) What is a high oil temp? What point should I be worried. I plan to run with some top oil in her.

4) What oil pressure should I be worried about at high revs?

5) Do I need to monitor AFR readings? what will this do? Does rich or lean mix cause det?

6) Should I have bought a Golf???????????

Thanks Guys (and Gals)

 

Your main cause of det would be the Jap map that is in the ECU, The STI V2 RA has a chip that can be taken out of the ECU and a map put on it, and is very similar if not the same as the ESL style. I would take the chip out and have a generc 'safe' map put on it for a start (PM me for details if you want) I had this done for a scoob I have.

Secondly, oil starvation won't be doing you any favours, you can either pay 450-500 for a proper sump, or get yours welded up (I can post a pic if you are interested?)

High oil temps depends on what oil you are using (10w/60?)

Should I have bought a Golf??????..... depends on your pocket.

 

I'm no scuby expert (I'm on here to get some info 4 the engine I'm rebuilding) but seems like a logical approach your taking to me.

I would imagine oil starvation would be the most sure-fire way to destroy any bearing, but extreme detonation may be enough to do it, maybe?

Detonation is caused by the compressed mixture self igniting. The higher the pressure and/or temperature in the cylinder, the closer the mixture will get to the flash point where it can detonate. Localised hot spots (eg a part of the piston crown or cylinder head which is not cooled as much as other parts) will bring it on sooner, lean mixtures are much more likely to detonate than rich, and ignition timing is also a significant factor.
Obviously a higher octane fuel has more resistance to detonation.

So yeah, monitoring oil pressure should tell u if oil surge is the problem, and if you can monitor knock and oil temp as well then you should be able to figure out where the problems coming from.

 

Thanks 500.

I'm going to running silkolene pro s next time out, 10/50 I believe. So your saying that an excessive oil temp is in relation to the quality of the oil. I.E. the point at which it loses it's performance? In which case I should check the operating temp for that oil?

As for the sump welding? IA pic would be nice as I have not got a scooby what you mean.

Thanks again

 

I would have thought so, as there are different temp ratings, think it would be related. 120 seems to be around the max temp. if you need to run an oil cooler, DO NOT use a sandwich plate, but the take offs on the pump itself that are blocked off with allen blanks.


Sump is to be welded around the outside and plates welded in. Compare this to your own and you will see what I mean

you may need to wait a min for the pic below ..

 

what's wrong with a sandwich plate? Going directly off the oil pump will cause BIG problems.

 

What probs will it cause Paul, I'm curious as to why Prodrive choose this method.

I was under the impression that sandwich plates ate no good for the subaru's, or is that just for the sensor take-offs?

 

Sorry if i'm being a numpty but what is gained by this mod??

 

If you take the oil feed from the pump, and then back into the other blanking plug on the pump, you will bypass the filter and engine, feeding oil through the cooler and straight back into the sump! To do what prodrive do isn't straight forward, and for the most part not required.

Sandwich plates work fine, but you need to do a proper installation of all aspects of the oil cooler, and there are many ways to do it.

 

looks like a baffled sump, stops the oil sloshing around, these types of sumps are used in all sorts of cars, especially ones which are used for track / dirt racing.

Dave

 

I got my baffled sump from APi...
For alot less than £450-£500...lol
Think it was around the £130 quid mark...

 

Thanks guys,

The sumps are baffled as standard but I can see how improving it may be benefitial. I've got my oil pressure gauge now, so I'll tootle (ish) around and see if I have any pressure probs when hard cornering first before modifying it.

Gary

 

I've had an oil temperature and pressure gauge fitted for over 2 years with the standard sump (I recognise what's been done after looking at mine), including track days and always driven hard. I've never noticed and fluctuation on either gauges during this time apart from the normal (2.5bar-3.5bar when warm on tickover and 7 bar when driving and cold)

If it helps

My 93