Advice on fuel mixture please

[SOL_LADY]

Help please!!!

What would be the correct fuel mixture for a Chrysler 75HP-"Two Stroke" Outbord motor???
So far I have been advised four different measurements

Thank you in advance,

Gae

[angler 3.55]

have a look on the side of yr motor and it should say 50:1 or sumthin

[SOL_LADY]

Thanks angler 3.55 I will do that in the morning.

Many thanks

Gae.

dunno bout these old school motors these days maybe better off buying a yammie 4 stroke no oil mixture needed or cheaper option is get a oil injected 2 stroke.


cheers brad

Most Chryslers are at least 25 to 30 years old these days!

Luckily I'm half as old as that again - and can remember the good ol days!

8 pints to a gallon etc - used to be imperial measurements - we learned em at school....along with pounds shillings and pence!Then in 1966, some peon in govt decided to screw with everything and we've been decimal currency & later metric, ever since....but I digress!

When two cycle engines first came out over 50 years ago - they used to run from memory on a pint of engine sump oil (not the later tcw2 or tcw3 tcw = Two Stroke Water-Cooled...specially forumlated oils), to a agllon of gasolene/petrolium distillate.

To add to the confusion tho - there are English "gallons" = 4.45litres and a smaller "US gallon" = 3.84 Litres?

So - mixing 16 fluid ounces (1 pint) of straight 20w30 sump oil with a gallon of gas was a little imprecise depending on which "gallons" measure you used!

The sump oil didn't burn too well and would foul plugs in an hour or so's running and even worse at idle!

When engines evolved and so did fuels technonoly - the TCW 2 oils came out designed with low ash contect to better combust and foul plugs less - they moved to 25:1 fuel / oil ratio...which most likely is what the Chrysler would run best on!

Now that we have even more refined TCW3 generation oils - you can probably get away with running 50:1 blend (Unleaded petrol has less octane rating anyway!) Don't foget a lead additive for the new unleaded fuel for such an old OB - it may require it for upper cylinder lubrication....since it was designed to run on the old leaded "super" grade petrol! The increased lubricicity of the TCW3 over TCW2 is what allows you to probably run TCW3 at half the ratio of the old TCW2 generation oil!

We now have even MORE advanced 2 stroke oils like "synthetic" - that can be run in 2 stroke engines at 100:1 ratio's

Some of the variable computer injected 2 stroke engines (e.g. Etecs) run blends as low as 120:1 during some parts of their rpm range...where its designed, they can get away wth it!

I would think for the Chrysler with the new TCW3 oil - you COULD run OK at 50:1 in the old chrysler - but if you wanted to play SAFE, you could mix the new twc3 oil at 25:1 ratio (sometimes called "double oil" to reflect the ratio some new 50:1 outboards are run in for at breakin period!).

So with TCW 3 oil then mix 25:1 to play safe - or 50:1 if you intend to do a lot of low idle work and can't endure the plug fouling issues!

It's not like the oil ratio is an "exact science" with engines of that particular vintage! Anywhere from 25:1 to 50:1 blend ratio will probably work, using the new TCW3 Generation oils!

Maybe start wth a 25:1 blend.......run it and see how you go...and if plug fouling is an issue - gradually taper back your blend toward 50:1 ratio over successive tanks and see if the plug fouling issue improves, until you find a ahppy medium for the Chrysler!

The biggest problem for you is the lack of super grade fuels the engines designed to run on (98 octane rating)...and the absence of lead in the fuel - you CAn get an additive for unleaded to add both lead for old engines that require it for upper cylinder lubrication, and to increase the octane rating so such high compression engines don't "ping" (pre-ignite just before TDC - Top Dead Centre) of the engine piston stroke due to low octane rating unleaded fuel.

You have to buy this additive from your servo and mix it with the unleaded fuel, on each tankfull.

good luck!

[SOL_LADY]

Thanks for all the advice everyone,I really do appreciate it very,very much

Best to you all

Gae.

[Rossco32]

Originally posted by trouty

The biggest problem for you is the lack of super grade fuels the engines designed to run on (98 octane rating)...and the absence of lead in the fuel - you CAn get an additive for unleaded to add both lead for old engines that require it for upper cylinder lubrication, and to increase the octane rating so such high compression engines don't "ping" (pre-ignite just before TDC - Top Dead Centre) of the engine piston stroke due to low octane rating unleaded fuel.

You have to buy this additive from your servo and mix it with the unleaded fuel, on each tankfull.

good luck!

Super was actually 94 (RON) or 92 OCTANE.... The only 98 OCTANE fuel is avgas ~ specifically 98 (110 RON) Low Lead.

BP and Shell both produce (BP Ultimate 98 or Shell optimax) but they are both 98 RESEARCH OCTANE NUMBER (RON) fuels that are really 95 OCTANE fuels

RON numbers and Octane numbers are different measurements of the fuels anti detonation properties and nothing else.....

Fuel companies here switch from Octane to RON with the advent of Unleaded fuel, They did not make it public knowlege at the time....... BUGGERS!!

All standard (NON EFI, DFI) outbords have low compression around 7- 8.5 :1 and will run on 85 octane (89 RON regular unleaded) Just fine with out modification.

2 strokes don't have valves thus do not require valve lubricant additives...... upper cyl lube? the oil in the fuel does that like it always has in any 2 stroke.....

And any octane booster you use will be a $25 waste of money in an outboard!.....

Wouldn't the person that sold it to you know the fuel mix?

[Angel]

Hey Rosco, is there any advantage gained from running premium ie BP ultimate or is it not worth it?

[Timmah]

chase444,

the best thing to do mate is just buy some top quality oil and go by that mixture. Cos different oil qualitys are designed for diiferent mixtures. I sell stihl equipment and we use oil made by castrol which has been designed for these machines but some other oils are design for 25:1 and so on.

Cheers
Tim

[Noddy]

Chase run it at 50:1, I have a 30 year Johnson that I run at that mixture and have never had a problem with it. Works out to 200mL of oil to 10L. I stuffed up my mixtures once and run about 30L of fuel through it at 100:1 and it still didn't seize. I use BP Ultimate 98 and Shell Nautilus Marine 2 stroke oil. I use the BP 98 as it burns alot cleaner and prevents any carbon build up un the piston. I also run my cars on 98 or Shell premium for the same reason, I also get better milage from these fuels.

[Rossco32]

Originally posted by Angel
Hey Rosco, is there any advantage gained from running premium ie BP ultimate or is it not worth it?

First off BP ULTIMATE IS NOT PREMIUM UNLEADED (PULP)
pulp is 95 ron, ultimate is 98 RON, just 3 ron points HIGHER than PREMIUM unleaded.

No there is no performance difference in non EFI motors.... 2 stroke Outboards don't run high enough compression to gain power from it's 3 point higher RON rating.

BP ultimate does contain better fuel stabilisers and detergents than premium though..... but not enough to warrant an extra 12 cents per litre.....

If we were talking turbo EFI engines (cars) then YES ultimate is just that..... I ran a daily driven 440 hp 13b turbo mazda rotary for 3 years on Ultimate..... I love the stuff.

Just a waste of $$$ if you motor isn't tuned for it (unless it is self tuning i.e. Injected and O2 sensed).

Also it DOES NOT burn cleaner than pulp unless your engine is tuned for it's higher RON numbers (AND NO! no manufacturer tunes standard cars for 98 ron fuels), That means if you've chipped or boosted your car then yes ultimate can be a standard diet for your car, boat, bike etc.

But for a standard modern engine tuned for 91 ron ( read ALL general productuion engines - Except high performance engines ie STI Subaru, Skyline, XR6 turbo, BMW M3, M5 or M6 etc) you are just wasting your money as your engine cannot utilise the octane advantage of the fuel........ You might have a slightly cleaner FUEL SYSTEM after 100,000 kays but that's about it.

I currently drive an 89 Bmw 535i manual (160 kw standard and designed for 91 octane fuel from the factory)..... I have a european tuning 'chip' (from Dinan) installed in it tuned for europe's 95 octane fuel giving 185 kw........ On our 95 RON PULP it pings it head off on ultimate 98 it doesn't.....
I emailed Dinan to find out why and was told our 98 RON fuel is the same as their 95 OCTANE and our 95 RON(pulp) is actually 91 octane....

Confusing HUH!?!


Rossco

[madsurfe]

Don't foget a lead additive for the new unleaded fuel for such an old OB - it may require it for upper cylinder lubrication....since it was designed to run on the old leaded "super" grade petrol!

Trouty

2 strokes were tuned to run on Standard as it was known in the old days and there are no upper cylinder lubrication requirements in a 2 stroke. Upper cylinder lubrication is only a problem for pre 1986 4 stroke auto engines or old small ancillary motors that don't have hardened valve seats.

This is not personal and I would like to see you take some of it on board.

When it comes to outboard engineering you should sit back and learn instead of gobbing off because your lack of understanding can cause real harm in the advice you give.

You did yourself no favours bashing ETECs or any other injected 2 stroke so have a look at page 7 of this pdf. A well known WA company helped develop the injection systems for BRP, Mercury and Tohatsu.

http://www.orbeng.com.au/orbital/abo...df/engserv.pdf



Rosco clarifies all the relevant points especially considering the difference between RON and Octane ratings. Well done on the explanation.

Noddy is spot on regarding 50:1 and back in the early eighties I used to water ski behind a Chrysler 140 that we ran hard all day on 50:1. Only problem we had with it was coil related and eventually my uncle traded it on a Merc 135 and god that motor sounds great. He still has it!

You can get manuals from this American website

http://www.marineengine.com/manuals/chrysler_outboards/

All I will say is this. (And likely it's a lot more than I should!)

The beauty of the internet is that you have the ability with google search engines etc to discern from any replies you get - what action to take - which parts of who's advice to acept.

At the end of the day - you accept the personal responsibility for what action you take.

Etecs suck and awlays will!

I am 100% sure that you will NOT cause ANY damage to a 75 Chrysler if you run the new TCW 3 oils with unleaded petrol and a lead replacement additive, at either 25:1 or 50:1 ratio as I advised!

In that respect there is absolutely NOTHING whatesoever wrong with my advice insofar as it may damage the engine - so I stand by what I've written and you are 100% wrontg and an idiot into the bargain for suggesting so!.

I will never fail to give advice if I think my considerable experience and qualifications enable me to do so - and I will never try to stop anyone else from giving their own advice (including yourself no matter how self deluded it may be!).

Let the readers decide Mad Surfe. That is their prerogative!

All your reponse tells me is that your too imature to be able to cope in the real world where not everyone listens to ONLY your sage advice - if you are so insecure in yourself - you will one day perhaps grow up enough to realise that - in trying to tear somone else down to your size - publicly, it doesn't increase your own stature at all!

Frankly I don't like ya much at all, but tolerate you because your young and don't know any better manners most likely....so this occasion, Ill let it pass - but it's getting old - so why not go find someone else to tear down to your own size!

I am too old a dog to be taught new tricks by a pup such as yourself.

When you have the experience to back your keyboard skills, then come speak to me - otherwise just give me a wide berth and we'll get along just fine!

I will never type - whatever it is you want me too - in order to keep you happy - to me your still just wet behind the ears - fulla piss n vinegar - and thats a sign of immaturity - perhaps grow up a little and realise - the whole worlds full a assholes and opinions and we all have one of each - nuthing you say will stop me expressing my opinion if I feel I can help - and theres definitely nothing in any of my advice that might harm anyones engine so back off coz your making a fool of yourself with claims you cannot support for purely ego reasons!!!

Builfd a bridge and get over it Mad surfe as Foghorn Leghorn would say - this kids about as sharp as a bowlin ball! Ya startin to bug me kid - ya ain't no chicken hawk and i ain't no chicken!

Got the message?

Cheers!

[madsurfe]

In that respect there is absolutely NOTHING whatesoever wrong with my advice insofar as it may damage the engine - so I stand by what I've written and you are 100% wrontg and an idiot into the bargain for suggesting so!.

thanks for that

Let the readers decide Mad Surfe. That is their prerogative!

np's

I am too old a dog to be taught new tricks by a pup such as yourself.

np's but you must be thinking of someone else cos' I remember imperial currency well and didn't use a calculator at high school but rather a slide rule.

thanks for the reply