28 replies to this topic

[NeilR]

I have recently been gifted my uncles mk1 Ford Capri V6, purchased new by him in 1970. This is the Ford Europe car powered by the British Ford 'Essex' v6. The heron-headed 60 deg V6 was never that much of a performance engine at 140bhp from it's 3000cc. Things like 64mm diameter crank journals do not help and these days it is a bit of an orphan of an engine for parts, which poses a few challenges. Pistons can be bought but unbranded cast pistons to the original design are 640 UK pounds per set and forged pistons are more expensive. Many have resorted to using pistons from different engines and this was a path I have been investigating. The piston options include those from a Buick turbo V6, aftermarket forged pistons for a turbocharged M3 engine - curiously cheaper than the cast Essex pistons. Finally VW Wasserboxer van pistons are also are 94mm in diameter and have the deep dish on the top. Interestingly the latter two options were dismissed buy the engine reconditioner as their 'slipper', short skirt design was deemed unsuitable in a 60deg V6, though the stroke is modest at 72.42 mm (2.85 in) and can potentially increased to 78mm with an offset grind and Chev rods. Personally I did not think the design was a problem, but are there piston design issues I am unaware of in using a piston from a flat4/I6 in a V6?

[kikiturbo2]

I would say, check for valve clearence first.. esp if you take pistons from a 4 valve engine.. As for skirt design I see no problem.

 

BTW, I had that car.. mine was mk2 but also 3litre with ghia equippment and vinyl roof.. great car that wanted to go sideways everywhere..

[carlt]

contact Ric Wood - he's the top guy for all things ford essex v6

http://www.ricwood.com/essexv6.html

[NeilR]

I did contact Ric. His 10:1 pistons are 780UKP + vat.

Piston clearance - the pistons would have to be machined to suit. 200bhp would be the aim.

[Magoo]

To answer the question directly: A V6 has no special needs in piston skirts vs an inline engine. 

Edited by Magoo, 24 October 2015 - 03:30.

[NeilR]

Thank you Magoo, very helpful. The Buick V6 pistons are from a 90deg V6, but I assumed they were virtually identical in design apart from the offset pin. Heron head engines do add that level of difficulty.

[Lee Nicolle]

Have a look at Keith Black pistons or similar. Or even Mahle US. I suspect they will make a decent hyperuetectic piston that will be cheaper than the pommy ones. And probably better too. That engine I feel would bve best served by pistons made for it. Bowl in piston requires a correct bowl. 

For a normal style engine adapting pistons usually works.

not my favourite engine but they can be made to go quite well.

1970,, I feel that still has the 4 cyc diff and gearbox? Be gentle with them. Though any V6 Capri is a nice cruiser at this point in time.

[Catalina Park]

Try Graham Russell in Sydney. If he can't supply pistons he should know someone that can.

[NeilR]

It has the heavy steel cased gearbox and Atlas rear end Lee, so it can take a little more power. They were only made/available in Aust for 3-4  years I think, so the later thicker block and 'd' port heads never made it here. Ric Wood's pistons have a shallower, wider bowl, which also seems in favour with the 4cyl engines too.

[bigleagueslider]

I'd bet that you can get a set of 6 custom pistons from someone like JE for less than the equivalent of 640 pounds UK. If you can provide all the dimensions/tolerances, JE is very good at producing custom pistons quickly and for a reasonable price. Probably cheaper than replacing both pistons and conrods.

[Lee Nicolle]

I'd bet that you can get a set of 6 custom pistons from someone like JE for less than the equivalent of 640 pounds UK. If you can provide all the dimensions/tolerances, JE is very good at producing custom pistons quickly and for a reasonable price. Probably cheaper than replacing both pistons and conrods.

Agreed.

There is/ was a supplier called Specialty pistons in Victoria. They too could make them though in my experience it is cheaper to buy from the US.

[NeilR]

JE pistons have become 30% more expensive in the past 4 months as the AUD dropped against the greenback.

[Lee Nicolle]

JE pistons have become 30% more expensive in the past 4 months as the AUD dropped against the greenback.

Not quite true though there is a fair difference.

You can email JE or whoever, or better call them if you have  suitable phone plan. I suspect still cheaper than UK stuff which to me often seems very expensive.

The problem will be getting a blank with a very thick crown so as to get the 'bowl' IF a Buick turbo piston is close that may resolve the issue as I beleieve they do have a moderate dish. But I doubt that finished piston will suit. Just the blank.

The specialist places use basic blanks for most applications for pistons, rods, valves and many other similar parts.

Bear in mind too that you may be able to get a smaller piston than the accepted 020 030 etc piston if your block is good providing there is a suitable ring available. The less you bore those blocks I have been told the better amd most Aussie cars have used water in them for decades and the blocks regularly fail. Sonic testing while great measures rust as wall! Worse, rust seems to find casting pinholes and flaws and make them holes.

Thought,,, try Bo Seton, he is still building engines. He knows a thing or two about those engines!

[Kelpiecross]

I suspect the only really safe solution to the piston problem is to pay the price for the genuine article - especially if you are spending a lot of money on the rest of the engine and the car. 

[carlt]

http://www.burtonpow...-19298-020.html

 

as in the post above,  power costs $ 

by the time you have machined the non std pistons to fit - whats the saving - unless you can get cheap non std forged ones

[MatsNorway]

I was hoping for a discussion about the rod length vs crank trow and piston skirt length in relation to that..

[bigleagueslider]

The piston skirt should clear the counterweight swing about BDC.

[Lee Nicolle]

I was hoping for a discussion about the rod length vs crank trow and piston skirt length in relation to that..

That is such a can of worms. What Neil wants is good std replacement components. Anything else is full custom and with bowl in piston possible custom castings/ forgings too.

 

Though rule of thumb, long rods make torque and often mid range power too. But the pistons generally wear out faster.

Interestingly long rods are often said to have unfavorable  rod ratios.

I guess the favorable ones come out of  theoretical book. So much for theory,, though for a passenger car hack engine it probably is correct.

[kikiturbo2]

why would long rods wear out pistons faster?

[NeilR]

Actually what I want is a piston that will work well and save money e.g. if the VW pistons worked then there would be a $650 saving...nothing to sneeze at! Std production in a 10:1 CR would be nice though.

[MatsNorway]

Lee: so the extra mass of the rod eats up any gains from the reduced angle then?

[Lee Nicolle]

Reputedly more side loadings, Not quite sure why as the 'angles' are in effect better. Probably because the piston is parked TDC for longer.Building more pressure. The same at BDC too ofcourse though no real load there.   I do know that it does happen. I do know that is makes torque on a race engine.

[Lee Nicolle]

About a minutes research. KB Silvolite. PN 3182HC. Retail $264.14.

tech@uempistons.com

[gruntguru]

Nice find Lee but wrong engine. V6 Capri was 3.6876" bore.

[Kelpiecross]

I have read for years about the effect of short or long rods on the power/torque of an engine  -  just what is the amount of difference in actual numbers  between short/long rods on the same engine?    

[NeilR]

Thanks Lee, but as noted wrong Ford V6 Essex.

[Greg Locock]

Kelpiecross- that's a great question. Gut feel - a very small difference in torque at a given speed, with the advantage to the longer rod, due to less sidethrust at the piston, offset in extreme cases by the increased mass of the conrod.

 

Here's a paper on a .closely related subject https://www.google.c...9543,bs.1,d.dGo

 

but I couldn't find anything serious (as opposed to hotrodder gossip)  on your actual question. I dare say a good engine modelling program would be handy at this point.

[Lee Nicolle]

Thanks Lee, but as noted wrong Ford V6 Essex.

Oops, I just saw 3L V6. How dare Ford make more than one. 

Had a long time engine builder here today and I mentioned this and he said buy the correct pistons, any piston, even a turbo piston will not have enough strength in the crown.

He said the same as me, KB or JE for reasonably priced custom pistons, or try the specialists.

Capri Components [Lawrie Nelson ] would be worth  try too.

[Lee Nicolle]

I have read for years about the effect of short or long rods on the power/torque of an engine  -  just what is the amount of difference in actual numbers  between short/long rods on the same engine?    

Every engine is different. HP figures will often be the same, torque will be more.

Decades of production based race engines tell the story. Amazing how .300 thou of rod length helps [Chev 5.7 v 6"]

Read Smokey Yunicks thoughts on the subject. Among many other US and Euro engine builders.

Often the biggest problem is the piston, 347 Ford [and others] have the pin behind the oil rings. That with 5.4 rods. That alone is not ideal, though for that engine [289/302 base] they are very torquey.