New Solution For Mi16 Oil Surge

[findlay 0]

Dazza,

 

In all honesty, your post is where we started with this debate a long time ago however, after much debate, examining head when off and taking practical experience into the equation it is the HEAD where the problem lies.

 

In comparing say, a GTi6 or 206GTi head it is possible to see that, not only has the oil gallery design been radically changed, but the galleries have atually been moved altogether when compared to the alloy Mi head design. The two galleries in the MI head are both small, one IS smaller than the other however and it would seem that, in lay terms, under high lateral G situations the oil in the head sloshes to one side and that single drain simply can't return the volume of oil that the pump can pick up.

 

This creates a situarion where the pump continues to feed oil into the head at a greater rate than it drains from the head until such a point that the level of oil in the sump falls below where the pickup can scavenge from and hey-presto the stop light comes on.

 

Decent Mi cranks are going to become very scarce in a short space of time and this whole debate will become pointless when everyone starts fitting GTi6 lumps instead

 

Hope this helps Dazza.

[Kitsune 0]

How could it be any less effective under heavy braking? If there is more oil above the pickup it has to be better than standard. Also, where can the oil go? Forward, up the long wall? If anything, the most likely point of failure is still a long left hander, when oil has more room to move away from the pickup.

 

I've never seen less than 30psi with the extended pickup, trap door sump, pump baffle, 6.5L design. I suggest you stick some sticky tyres on and try it. Sounds like too much theory and not enough practical to me.

 

 

Dont take it in the wrong way, I did only say might. I'm just gathering information from various sources.

 

And yes at the moment, it is all theory, as I stated, this is for a HNC project of which I'm only weeks into, so everything at the moment is theory. As it happens, I'm very interested in your extended pick up (what is the price to UK?).

 

What baffle design are you using which allows you to use your extended pick up? Is it a 'standard' design or something that you've done yourself?

[findlay 0]

I've had oil surge under heavy braking too but only after a left-right flick chicane and straight into a braking zone...

[Kitsune 0]

I've had oil surge under heavy braking too but only after a left-right flick chicane and straight into a braking zone...

 

 

Using the extended pick-up or not though?

[James_R 3]

I'll be using the extended oil pick up b january, hopig it will make the engine last better this time

Edited November 16, 2006 by James_R

[findlay 0]

Nope, sorry, on a standard Mi...

[sorrentoaddict 1]

Okay,

I assume it is a known fact that in F.I.A. Rallying dry-sumps are not

allowed. Let's see the facts:

The XU9-J4 engine (the alloy MI) is known most as being one

of the most succesful atmo "maxi" engines EVER in rallying, and, as a

Turbocharged version (in 206 and Xsara WRC), as one of the most

succesful engines in WRC ever.

 

Now, the most developed atmo-version of these engine was in the legendary 306 MAXI. These cars ran on sticky "one-stage-soft" 18"

factory-team quality slicks, and had a wheelbase/track and suspension (hence corner speeds on dry tarmac) that were literally MIND-BLOWING.

 

So I guess you will agree that the Peugeot Sport guys DID INDEED solve the "oil starvation issue", inherent on the standard-MI engines.

 

Now, as I have had the chance to personally see a completely dismantled MI-engine, coming out of a EVO-7 306 Maxi (engine originally built by PIPO), I wanted to share the following facts:

 

1) head casting and type is TOTALLY same as on any XU9-J4, i.e. "you-and-me" alloy-MI-16 engine.

2) spray-bars under the pistons were there (of course!!!).

3) conrods were piston located, so, yes, there was a "lot of oil being squirted out the big-ends..."

4) sump was baffled with a complex shape, which is still available to be bought in Peugeot-Sport - nothing TOO exotic.

5) oil pump was changed in the following manner:

- "Gr.A" release spring

- 28 teeth driven gearwheel & longer chain

- small shield on its pick-up - again, nothing too dramatic

6) THE NEWS: ALL the oil galleries in the head were heavily modified

(wouldn't disclose more here), in order to (as the cam followers were mechanic, of course) dispose with the need to gather so much oil in the lifters' "bays", and to make the circulation of the oil MUCH quicker back to

the sump.

 

That's it. No other measures of Lubrication enhancement were taken.

 

And we are talking of engines with a 7,000 - 8,800 rpm operating range,

MASSIVE lateral G-forces, and 13:1 C.R., which in spite of the oil-cooling gives the real-life viscosity of the engine a real tough time.

 

I believe this is enough to illustrate WHERE the inherent lubrication problem of the MI engine indeed is - and, of course, simply fitting mechanic cam followers (besides the other obvious, smaller anti-oil-surge measures to be taken that are valid for ANY race engine, ANY car..) will not cure the problem by itself. One needs to re-work and tap many "spots" within the head casting, in order to render the massive oil galleries inoperable. Then the MI-16 becomes only as oil-surge-prone as the 8v XU is - which is actually very little, and comparable to most other engines when they are modified for competition use.

 

 

Cheers

 

 

AG

[welshpug 1,677]

finally someone who's seen a works engine

 

 

(one small error there though, all Turbocharged engines in WRC PSA's were based on the Iron Block XU8, even though the capacity changed to 1998cc)

[sorrentoaddict 1]

welshpug, thanks, you're right - when I said "based", I meant that

the head design in general was basically XU9-J4, as obviously the

head galleries core design are to be blamed for the lack of "plug'n'play"

race applicability of this engine as a std. one (oil surge etc..)

[cybernck 403 1 Cars]

off topic alert!

 

good to have you back on here Alex!

 

where have you been to?!

[Mandic 0]

I second that, good to have You back!

 

But then again, fitting Xu10 sump + spacer gives extra capacity which substitutes that lost in the head, and all the other mentioned components can be found in S16 engine (trap door, chain gurad, pump trap door, different gearing, ...)

 

So if one has no need to change to solid lifters this is a way to go and I believe petert has proven it.

 

Cheers

 

Ziga

[welshpug 1,677]

I see what you're saying Mandic, but why spend this money when the cause and cure is known?

 

I suppose not everyone wants to rebuild their engine before driving it and would rather wait till it dies first

[DrSarty 100 1 Cars]

My word, what a thread! Fascinating read. Respect to those immensly knowledgable Aussies and Balkaneese(?) out there.

 

DrS

 

P.S. PeterT - could be your sump mods for me next then. Seems you have the answer and proof.

[sorrentoaddict 1]

honestly, I have very little time to be online lately.

But this is the best forum on the planet, so who could

EVER leave ??

[sorrentoaddict 1]

would add this, too: the piston-located conrods obviously "own" a big share

of the overall oil-flow/pressure-demand on these engines. That is why it is NOT a myth that on newly (and PROPERLY) rebuilt MI-engines (but ONLY ONLY ONLY if the crank is in very good nick), the chances of a massive oil-surge are somewhat smaller, and more rarely pronounced (if compared to a "tired" engine, where at least the big-end bearings are already "loose" so to speak for any serious (read trackday) motorsport use).

 

if any of you out there still wonder why piston-located conrods are actually better, there are 2 main reasons:

 

1. Less lateral friction of the conrod vs. other parts, as the surface of the small-end of the rod is (obviously) smaller than the big-end.

 

2. (MUCH MORE VITAL in race engines) This solution results in a total "isolation" of the conrods from the longitudinal movement of the crankshaft (crank is moving back-and-forth under gearchanges - due to heavy "racing" pressureplates, bulky transmissions, slick tires, LSD and other "longitudinal-shock-inducing" environment).

This prevents the conrods from slight but important vibrations at high RPM, where the piston is already too strained by itself "rocking" against the cylinder walls, and not to mention how bad it is for the pistons to additionally "burden" them by an occasional (e.g. on gearchange at 9,000rpm) "shatter" at a direction which is 90-degrees to their normal "rocking"...

 

Some engines even employ fully-floating conrods, i.e. the conrod is "unlocated" (dislocated? ). The benefit of this is an even bigger saving in internal friction, i.e. more transient response.

 

That is why reverting to crank-located conrods is totally retrograde technically speaking, and increases the reliability risks (mostly piston-related) at high RPM, when the car is used in serious conditions (slicks, strong clutches, straight-cut gearboxes, LSDs, and the like..)

[James_m 0]

I still think external drains from the head to sump is probably the most practical solution. I wish id have looked into it more, but my engine is finished now so i cant be bothered to take it apart again. I think it was livelee who posted a video up of a 309 on track with the extended pump pick and trapdoor sump and whilst it certainly helped and was probably now good enough for a road car, the pressure still dropped worryingly at times. Anyone know of anyone who has actually tried the external drain mod?

[philfingers 5]

I wonder if you could set up some kind of U tube arrangement my modifying a sump plug. This would give the level of the oil in the sump visible through the wall of a clear plastic tube. Obviously the car could do with being up on stands. Make sure the sump is full to the top of the dipstick, then run the engine, vary the speed and see if the level in the tube drops. Obviously the problem here is you can't drive the car so can't see the effect cornering has on the oil level. Use an old sump plug and it's easy to put back to standard.

Does a dry sump solve all the problems? If it does all well and good but there's the extra cost and weight and really with all the extra weight is it any better than a GTi6, probably not, the only benefit is that you can distribute the weight a bit better.

I'm considering building another 205/309 road rally car and using an Mi as rules now allow this but the more I read the more I'd stick with my trusty 8v.

[Kitsune 0]

Anyone know of anyone who has actually tried the external drain mod?

 

I'd love to know this too as it's still my HNC project. I'm still working on other areas of the project though so haven't got into the finer detail. It's also something I am seriously thinking about as my engine is still out of the car, just depends on what I can find out about this mod.

 

I would love to know where best placed the drain should be (cambelt end/dizzy end/both/middle and where on the head?) and possibly what diameter pipe to use. Also, is a small scavenge pump worth fitting? I've stil not managed to get a head which I can use to chop up but that's my own fault at the moment.

 

There seems to be different stories about Longmans doing this conversion and (from this thread or similar) and also pug sport themselves doing this. Going through some old threads on here it seems there are a few people 'that know people' that have done it, but with no more info over and above that.

 

If anyone does have any more info, I would love to know.

[crf450 0 1 Cars]

would add this, too: the piston-located conrods obviously "own" a big share

of the overall oil-flow/pressure-demand on these engines. That is why it is NOT a myth that on newly (and PROPERLY) rebuilt MI-engines (but ONLY ONLY ONLY if the crank is in very good nick), the chances of a massive oil-surge are somewhat smaller, and more rarely pronounced (if compared to a "tired" engine, where at least the big-end bearings are already "loose" so to speak for any serious (read trackday) motorsport use).

 

if any of you out there still wonder why piston-located conrods are actually better, there are 2 main reasons:

 

1. Less lateral friction of the conrod vs. other parts, as the surface of the small-end of the rod is (obviously) smaller than the big-end.

 

2. (MUCH MORE VITAL in race engines) This solution results in a total "isolation" of the conrods from the longitudinal movement of the crankshaft (crank is moving back-and-forth under gearchanges - due to heavy "racing" pressureplates, bulky transmissions, slick tires, LSD and other "longitudinal-shock-inducing" environment).

This prevents the conrods from slight but important vibrations at high RPM, where the piston is already too strained by itself "rocking" against the cylinder walls, and not to mention how bad it is for the pistons to additionally "burden" them by an occasional (e.g. on gearchange at 9,000rpm) "shatter" at a direction which is 90-degrees to their normal "rocking"...

 

Some engines even employ fully-floating conrods, i.e. the conrod is "unlocated" (dislocated? ). The benefit of this is an even bigger saving in internal friction, i.e. more transient response.

 

That is why reverting to crank-located conrods is totally retrograde technically speaking, and increases the reliability risks (mostly piston-related) at high RPM, when the car is used in serious conditions (slicks, strong clutches, straight-cut gearboxes, LSDs, and the like..)

 

This is the opposite to what I was lead to believe by the bloke that developed the late MI (S16) 405 works touring car engines in the late 80's, he was horrified when he realized that I'd ordered my rods off Arrow to be made piston located. I am very surprised the S16 maxi engine had piston located rods,could you be mistaken? I thought that Peugeot reverted back to crank located rods on all XU engines after problems with the Mi.

Does anyone know which modern engines run piston located rods?

[sorrentoaddict 1]

No, I am not mistaken, the rods in this very engine were

not crank-located.

 

Touring-car engines might be a different issue compared

to rally-engines, as the latter ones are meant to "survive"

2-3 days (sometimes as much as 300 very hard S.S. km

with 600-800 "normal" km in between them) without rebuilds.

 

And crank-located conrods can only be bad for reliability,

due to transferring various "shocks" to the piston groups'

planes of motion.

 

Yet, on 200km-or-less-betw.-rebuilds BTCC engines, this can

of course be tested & compensated with piston design,

tolerances etc., so Longman might have used crank-located

rods indeed.

 

IMO, it is just a different "big picture" on the overall engine-concept

issues, that a professional high-budget race-engine builder carries

in his head - as opposed to most of us guys here who are almost always working within a reasonable budget, and most definitely without the extensive car-industry support these guys often enjoy.

[Sam 4]

Some time ago I spoke to a local enginetuner about the problem. He's not Peugeot-specifik and I got the understanding that in general it's quite common to drill and plumb externally.

So maybe it's common with DOHC design that oil gets trapped in the head!?

 

Yep RB26DETT for example.

 

Sorry to bring this up I was looking for info on solid lifters...

[Rik 0]

To further Alex's post on the fact that the head was heavily modified so the oil return was quicker....

 

Making the assumption here that the same amount of oil enters the head with a normal capacity sump compared to the extra capacity sump as in peters set-up.

 

I believe peter taylor's setup does all of the gearing, group a spring etc) apart from the above head oil gallery modifications, but i beleive to combat this petert has made the sump and pick-up deeper - thus allowing more oil in the sump.

 

therefore...

 

IF theres oil going into the head and not coming back quick enough - all is ok cause there is extra oil there i the first place due to the increased capacity.

 

Rik

 

P.S Kitsune - you dont HAVE to finish the HNC project.... so long as you do what you can and conclude what you havent. I got a merit - just exaggerate everything

Edited May 15, 2007 by Rik

[veloce200 3]

I've mentioned this a few times - no one seems to have tried it - electric scavenge pump.... from head to sump - m5 bmw has 4 of them!

[Ryan 99]

I've mentioned this a few times - no one seems to have tried it - electric scavenge pump.... from head to sump - m5 bmw has 4 of them!

 

Is that only the newest M5 (the E60) or did the E39 have them too?

[Batfink 201]

I've mentioned this a few times - no one seems to have tried it - electric scavenge pump.... from head to sump - m5 bmw has 4 of them!

 

I'm going to fit one to mine