Toad's Lifeline - Saxo Cup front suspension purchased!

[KamRacing]

I guess the thing to do is work out where the oil is being used. Its probably something like the piston rings. I dont know a lot about these as I dont build engines but some are going to be better than others and some will cope better with high piston velocity. I cannot see masses of oil being lost through the valves

[Lewisimo]

Also I had to replace the plugs on my engine too - apparently it used to go through plugs a fair bit when Bic had it too. That may be due to the fact it runs so rich though (atm). Don't fret brother, wait until it breaks then worry!

[Toad]

Originally Posted by Lewisimo

My assumption would be that super high revving engines simply burn more oil due to how hard they are driven. What oil you using mate out of interest? I know Bic's first engine (180bhp back in the day) drank oil towards the end of it's life. I'm pretty certain his second one (my one) now used a reasonable amount of oil too. To be honest as long as it's just using oil and nothing fucking up I wouldn't worry about it too much! If it breaks just go back to pug1off! What did he say about it?

As Ryan said, a few of the previous longman engines 'burned' a lot of oil but I don't think widders had problems with his as far as I know. They built loads of rally cars engines for cars in Ireland so that business wouldn't come on the back of bad workmanship. Also the touring car heads were all done by Longmans too (the pug one's etc). I would really put it down to the fact the engine is working a lot harder than normal therefore the oil is being put through the paces to a higher degree. I would ask Sandy for a definitive answer, although as usual i'm sure it could be a million things! When mine is working i'll let you know how it goes on oil!
Try millers stuff, it's not cheap but it's designed for these high revving engines - i'll check what i've got in mine and let you know mate.

Matt seems to think it's OK. He just makes up excuses, lol. He said it's because of the gearbox keeping it in high revs, and they naturally drink oil. He's got a turbo 205, and he said he had to take a 5ltr can of oil to the Ring due to it drinking oil. He just said it's normal.

So at the moment, the concers are:

- Oil consumption
- Sooty sparkplug in #2 cylinder
- Oil smelling strongly of fuel
- Very low compression in all 4 cylinders

But it's driving great.

[Toad]

Originally Posted by KamRacing

I guess the thing to do is work out where the oil is being used. Its probably something like the piston rings. I dont know a lot about these as I dont build engines but some are going to be better than others and some will cope better with high piston velocity. I cannot see masses of oil being lost through the valves

The machining they have done is second to none. The equipment used is amazingly precise, so it seems unlikely that would be to blame. Remember the first engine I took to Matt? It was from Adamhighfield, and Matt thought it was a disgerace, and showed me just how bad the work was on it. So i'm possitive Matt knows what's required for a proper engine build. I'm still thinking dodgy injector in #2 cylinder.

I'm hopefully going to visit AlexR this weekend, as he'll help me diagnose any shizzle.

[KamRacing]

if the oil is smelling of oil then there could be an issue here.
It sounds like bore wash.
if the piston rings are fine then the next culprit is usually too high pressure fuel regulator. What are you running on this engine?? This could explain running rich too.. something certainly worth sorting!

[Toad]

If the fuel pressure regulator was too high, wouldn't that make the overall AFR obviously rich? The FPR wouldn't effect just one cylinder, so it might be a sticky injector in #2 cylinder, as this cylinder is obviously running rich due to the sooty sparkplug. I don't think the FPR has been changed from standard.

[KamRacing]

its just one scenario of many, though if you have just testing the fuel mix then its unlikely, as well as unlikely to be a sticking injector or something like that - its worth eliminating as parts can fail..... With the low compression personally I'd be looking at the rings. High compression can cause fuel to mix with the oil from blow by due to poor ring seal. What were used in your engine? OE? Are these up to the job. Were they bedded in right? have you changed your oil since running in? How quickly is the petrol getting in to the sump? Lots of questions to start to get answers for to eliminate and move on to other scenarios
Ask around a few engine builders on what they use for high compression engines...

Kev

[Lewisimo]

My oil smells of fuel too but it's running way too rich which is causing that. I will get it remapped when it's done.
As Kam said, too much fuel pressure or not mapped correctly! Check the injectors too I guess?

[AlexR]

Widders didn't have oil consumption problems because his pistons were original factory ones Whereas dodsons etc had high comps, hence the quality of boring/honing/pistons/rings and break in period were different to standard causing high consumption.

QEP engines and josh' engine don't use large quantities of oil with high comps so that says soemthing to you?

The 708 vs std consumption is the stem seals and extra blow by.

[Lewisimo]

Originally Posted by Ryan

Dans engine wasnt built by colin, it was built by longmans which pug performance were customers from.

On the ring trip alex came back saying it was drinking oil for fun. Dan beadles engine iirc was no where near as bad.

So did widders' car use oil as well?

[Lewisimo]

Originally Posted by AlexR

Widders didn't have oil consumption problems because his pistons were original factory ones Whereas dodsons etc had high comps, hence the quality of boring/honing/pistons/rings and break in period were different to standard causing high consumption.

QEP engines and josh' engine don't use large quantities of oil with high comps so that says soemthing to you?

The 708 vs std consumption is the stem seals and extra blow by.

So what are we saying then brother?

[AlexR]

That the engines that consume oil have a problem with the piston ring seal. This could be caused by many things, most of which are mentioned in my post. I could expand but i'm packing to go home for christmas so no time lol

[Toad]

The pistons are Wossner, and the rings came with them.

As I'm going to Northampton Motorsport soon'ish, I'll leave things as is for now. Hopefully we'll get an idea of what's going on then.

I'm keeping a close eye on mileage Vs oil consumption now, so I can get some accuarate readings. The oil has been changed twice since the build, and had lot's of top-ups.

Going back to the sooty sparkplug... If all the cylinders are showing the same compression, it would seem unlikely that the rings on that particular piston are to blame. Surely the only other explanation is the injector?

[Lewisimo]

Here we go mate - some useful knowledge from Sandy. Remember it's all his OPINION and he's not making judgement about anyones work, it's purely for information purposes! I think mine will use oil as much as your so don't fret too much mate...

This is a very difficult thing for me to reply to, without casting doubt over people's standards.

Speaking from experience, if any engine is using more than a litre every thousand miles during general use, it needs attention IMO. Race engines running at continuous high rpm may well use more by virtue of the pressure differences and velocities involved at those times, but only when running hard.

Something that's become very apparent to me over the last few years I've been involved with race engines professionally, is the standards of engine preparation, component precision, mapping and indeed the way the engines are treated, varies over an uncomfortable range and some of the well known companies have disappointed me; they say you should never meet your heroes and I know what they mean.

I had a very uncomfortable situation last year, when a well known 205 owner asked me to review his engine and solve a few issues he had with it, principally oil leaks and the power delivery. Once I had it apart, I found a raft of issues that made me wince and I wrote a detailed email to him, with pictures, measurements and solutions to explain and justify the work I felt was needed, he forwarded it to the firm that did the work!! The moral is, please accept or ignore the following as you wish, comment by all means, but if you choose to convey any of it elsewhere, please understand that I am generalising and not pointing at anyone in particular.

The principal cause of oil consumption is likely to be piston/ring/bore related. Either by the side effects of crankcase pressure or by poor oil control. These problems relate to the seal that the pistons and rings can effect against the bore. The main factors are:

Piston to bore clearance: As Phillip's mentioned, forged pistons tend to expand more, both due to their structure and often being run harder than original types. So more initial clearance tends to be needed to allow for that. There is a tendency by many to play safe and machine more clearance than is needed, maybe in the belief that it's more reliable (!!!), or it means less friction and hence better power ("a loose engine is a quick engine" (!!!!)), or often simply because they don't have the skill or equipment to make precise clearances and so can't risk it.

Piston quality: All forged pistons are not equal and over time I've evolved a short list of piston makes I will use and it excludes some well known ones. Not because they affect power necessarily, but simply because I cannot achieve the quality I want with the standard they are made to. The material is a factor but the main issue is shape and finish. Pistons are not round in section, they are barrel shaped and oval to account for the thermal and stress expansion. Some makes have these qualities much better worked out than others. A piston designed successfully in this respect will seal and control the oil noticeably better hot and cold. There are further shape related issues that aren't directly related to this topic.

Ring quality and shape: The rings are the only real "contact" between the piston and the bore, or they should be!! They need to accurately match the bore shape, the end gaps need to be tight enough to seal well, but must not risk end to end contact and the rings must have the correct amount of "radial tension" to push them out against the bore. Material is again important, but the majority of available rings these days are of good material quality. One of the biggies on this is if the rings are matched to the bore size, some makes use round sized rings (ie 80mm rather than 79.5mm or 79.7mm) gapped down to size to reduce sourcing and stocking range and hence costs. This practice requires more careful running in, because the fitted ring will not have the correct shape or radial tension pattern, the applied pressure will not be equalised, so it make wear unevenly over time. Rings ground to the bore size will run in quicker and last better, but it can be difficult to get information on what is supplied. The end gaps need to be radially correctly and set correctly to provide a suitable seal. It's not unknown either for rings to be upside down, but that's a rare school boy error. Rings can also easily be damaged as they are fitted to the piston or as the piston is fitted to the bore.

Bore preparation: The majority method is to bore the cylinder very slightly undersize and then hone with a 3-leg hone in a drill to the final size/finish with the block open and at room temperature. You can achieve a high level of precision with this method, but it takes great and rare skill. It's easier to get a high level of consistent precision finishing using a suitable range of stone grades in a CNC honing machine. Not many have access to such equipment. The hone angle, stone grade and alignment can dramatically affect the running in process and subsequent durability. Some blocks will also require careful clamping, with a deck plate to replicate the stress distortion a bolted down head applies, experience will tell how important or effective that is; some builders will even go to the trouble of heating the block to operating temperature. Bore alignment with the crankshaft can also be critical, if there's a continuous side load on the piston, wear will be accelerated.

Mapping/fuel set up: If the mixture drawn into the engine has an ideal air-fuel ratio
and is burnt at the right time, then deposits will be minimal (which affects performance over time) and unburnt fuel will be less likely to pollute the oil. But that relies on a number of things, mapping alone cannot cover it, the quality of the mixture and burn relies just as much on the inlet design, injector type/size/position, ecu operating precision, cam profiles/timing/valve sizes, porting, exhaust design and spark plug choice. So how well thought out, tested and set up the whole package is needs to be taken into account. If deposits build up, the engine will go out of tune and it simply gets worse, unburnt fuel washes the bores and can reduce the effectiveness of the oil.

Lastly, the engine will need to be warmed up properly before hard use (luggin around at low revs is as bad as over-revving), have due care paid to operating temperature and be protected from damage by ingesting anything other than fuel and air!

If can conquer all the above, any modern engine can have good sealing resulting in low blow by and low oil consumption. Running in periods can be shortened massively and durabilty can also be extended usefully. But it doesn't come easily and with pressure on costs often prevalent, quality can suffer. Sometimes though, it can simply be down to not knowing any better.

[unreal106]

very vvery wise opinion there some food for thought! advice like this is hard to come by and needs to be taken imo

[raunchz]

Good read - thanks for posting that Lewis

[Toad]

Thanks for all the info Lewis, i really appreciate it. Give my thanks to Sandy too. Wouldn't mind asking him about the sooty sparkplug would ya?

Like I've been saying, I'll keep a close eye on the oil consumption. As Sandy stated, if it's more than 1ltr per 1000 miles, then there's a problem.

[LEE_VTR1]

sandy is a legend end off. I love reading his posts on rallye reg tbh you can learn alot just from reading his posts

[raunchz]

Originally Posted by LEE_VTR1

sandy is a legend end off. I love reading his posts on rallye reg tbh you can learn alot just from reading his posts

Agree'd ^ ^ !

[Lewisimo]

I personally think he knows more about these engines now than pretty much anyone else!

No worries toad - I will try and find out about the sooty spark plugs