Hi all. I am considering buying an 1 1/2" splash fed phoenix crank and rods. I have had a mildly tuned engine write itself off with a cracked con rod. It lasted several years. This will be my first attempt at building an engine which is why I don't want to go pressure fed. I simply want a fast road car that can be taken out on track also.
My questions are: have all flywheels got the same bore?
Will an oversized oil pump give enough pressure for the shell bearings?
Anyone have experience with such a bottom end? John
I am using an 1-1/8" splash feed Phoenix crank in a lightly tuned engine. I have every faith in it being more than adequate for whatever I am likely to do. I would think a 1-5/16 Phoenix would stand plenty of tuning. The lower rotating mass seems to me to be an advantage. The weak point is probably the connecting rods. Lighter pistons would help them.
I don't know about flywheels for 1-1/2" cranks, but the flywheel for 1-5/16" crank has a larger bore than 1-1/8".
I don't think the oil pump size affects big-end oil pressure. This is generated almost entirely by centrifugal force. An oversize pump will generate more flow. How much of this extra flow makes it to the big ends is difficult to guess. I suspect most gets flung about inside the crankcase.
The Phoenix cranks have an improved design of oil trough in the webs. This will give improved pressure at the bearings.
My thinking largely lines up with Jim's.
Inch & 5/16 Phoenix crank will surely do the business for you.
To go to Inch & 1/2 you really need to be pressure fed, then you could have a great set up, but all sorts of issues (mainly to do with cost) to deal with.
I would strongly suggest getting the crank and flywheel dynamically balanced, Phoenix are supposed to be but never had one that is.
Thanks for the quick replies. It as the con rod (which was cracked tested before the build) that gave away on my last engine. Not the standard crank. And I did touch 6000rpm at times. Financially I a pushing the boat out to buy the 11/2" Crank simply because I can get the phoenix rods. Another plus is the fact that tk they have shell bearings which can simply be torqued as I have little experience of working with white metal. And to be honest I don't know of anyone over here that does. So the postage costs of getting items home and back for testing and metaling would add up too.
I can speak from experience on this subject, I fitted an 1 1/2" splash fed Phoenix 25 years ago, I have throughly thrashed the engine ever since, regularly exceeding 6000rpm. It has had several rebuilds during this time and I replaced the shells once as a precaution, (not regrinding the journals). I made modifications to the oil pickup throughs deepening them and putting a radius on the entrance to the oil way, I believe great care is needed when alining the oil jets, simply pointing in the right direction is not good enough, I set up a reservoir around the oil pump and spin it with an electric drill. The standard overside oil pump appears more than up to the task, ensure that you radius the entry of the oil pick up. Restrict the size of the oil ways to the cam shaft and fit sealing rings around the out side of the bearings, it is amazing how much oil leaks here. Containing the oil in the sump is important as well, a windage tray and sump baffle are worthwhile modifications. I have built splash fed 1 1/2" engines for friends in this manner as well, again with no issues after many hard miles. If you can afford the rods as well as the crank then go for it, be meticulous in your build and you will have a very robust engine.
As long as you don't mind extremely regular oil changes you will not need a filter, and lets be honest for most of us the days of running a seven on the smell of an oily rag are over, so the cost of an oil change is of little consequence. My Nippy runs a pressure fed crank without filter and I have had no problems. In my opinion retro fitting a bypass filter on an already running engine is not really worth the bother, however if I am building an engine for competition or where original appearance is not an issue I modify the galleries and install a full flow filter.
I can see the sense in installing a large crank with shelled rods as it can be cheaper than a new 1/8" or 5/16" and then having to re-metal the rods. Even the best re-metallers' products can have problems which can be eliminated by having replaceable shells.
You may care to consider the crank and rods supplied by John Barlow. The finished crank is better balanced than a Phoenix and there is a cost benefit.
However, as Nick says, always dynamically balance the crank and flywheel assy. and ensure the weights of the rods / piston assemblies are the same.
You will need a larger bore flywheel for the two larger cranks than for the 1/8".
I also believe a standard pump is adequate.
shouldnt be a price difference, or at least they should cost the same to make. or did when i last had them made.
do ask if they are actually 45 degree, rather than 43 degree (renault). there is a difference were they will hit the crankcase.
which suggests the actual advantage of useing 45 degree rods.
1 5/16 45 degree should drop down the bore. you may find the 1 1/2 being larger may not fit down the bore.
personally if you dont already have your crank and rods yet, and dont mind which company supplies. i would put an order in with both john, and pheonix at the same time. with the agreement you can cancel the order if neccassaty.
ive found over the years, cranks are one of those items that never fit there expected manufacturers dates.
no point in putting an order in with one, to find the other produces in 2 months. and you are left waiting 12 months for your order.
pheonix are quoting me july for mt next order. which means ill be expecting them around october time.
i beleive pheonix are putting there prices up by another £50 plus VAT this year.
John, one upgrade I would recommend not just to you, but to all with splash feed lube.engines, is the modification of doubling up of the feed jets as in the "Austin Seven Companion" page 251-254. I run a relatively standard RP, but carried out this conversion about six years ago when I refurbished the motor. I use a standard oil pump but still have 4 b on the gauge when cruising. Jet adjustment is a bit messy but worth the time cleaning up the floor and changing the overalls .
Hi Peter, I understand the thinking and have no doubt four jetting works but my question to you is it really necessary, and on what basis. I and many others race engines with two jet lubrication and have never encountered problems, the only time two jet lubrication has failed in a situation which I have been able to investigate the cause can be attributed to some other failing then the number of jets. Sorry to rain on your parade, and it may be that you know something I do not, but with modern oils and meticulous builds I can see no reason to add the complication.
Gentlemen,it is only a suggestion,I am a belt and braces man myself,as far as KISS is concerned I totally agree,but the mod is a simple one which increases the potential supply for virtually no cost, I used copper brake piping and a brake pipe three way adapter from the old biscuit tin supply.Time for mod I can't recall but was only a few hours. I'm happy knowing oil is splashing around merrily in the crankcase, No oil leaks and low consumption, you pays yer money and takes yer choice.
There are some who go to the complications of pressure feeding the crank and that is far more expensive than doubling up on the oil jets. If A7's can be raced reliably with 2 splash feed jets where is the logic for pressure feeding? I have done four engines with 4 jet lube for road cars, 2 with bored out pumps. The main thing for me is it costs nowt, only my time and it might be better than 2 jets. I know this is all old stuff but is there any evidence of the superiority for pressure feeding?
I believe the bad reputation for 1 1/2'' splash fed cranks in racing largely came about during the 1950's because of failures with jet fed Nippy big ends. However if you examine a Nippy crank you will see that the oil pickups and drillings are so poor it is little wonder they ran ends, I personally don't believe it has anything to do with just having two jets. I can only speak from experience, and mine is that with a Phoenix crank 2 jets are entirely adequate for 6000 rpm racing in a well prepared seven engine, and certainly more that adequate for a road car. I am sure someone will come along shortly and provide us with all sorts of theoretical calculations as to why pressurisation is desirable, but the proof is in the pudding as they say not the cook book. Obviously if you wish to go down the 4 jet route it is your personal choice and unlikely to do any harm, I am just saying that I do not believe it entirely necessary, particularly on a road car, and that I spend my time focusing on other details.
Totally agree Ian. I have to say I have never run a big end on a splash fed engine and I've given them more stick than most.
What is not generally understood is the actual mechanics? of big end lubrication. The oil from the jet, or pressure supplied oil is not what creates oil pressure in the bearing - that is done by the relative movement between the crank pin and con rod. This is of the order of several hundred if not thousands of lbs per sq inch. As long as there's an adequate oil supply the bearing will create its own pressure. In the case of an oil jet it's easy to see that is what happens. With pressure feed, you need about 10psi to overcome the centrifugal forces acting on the oil in the crank oil ways. If the pressure is t high enough you can stall the oil flow and still show pressure on the gauge. That's why you need pressure, otherwise just volume would suffice.
Apr 22, 2017 - 8:57PM
Re: Crank advice
Correction That 10psi should read 10psi per 1000 revs.