5 replies to this topic

[ozz1]

I’m having an ex 70s miglia engine rebuilt - balanced crank and rods, powermax d-tops, 649 cam, single dcoe 45, modified 202 head. The ring lands on the powermax’s have worn beyond usable means so I need a quality race piston that can take 12:1 cr and withstand a sustained 8,500 rpm. Reluctant to spend £500 on a set of omegas I've found these:

 

Calver http://www.calverst....lat-top-0-040”/

Retromini http://www.retromini...products_id=449

 

 The Calver piston and the Retromini piston- the only difference being the Calvers are cast whereas the Retrominis are ‘squeeze-cast’, am I splitting hairs over whether its squeeze cast or not? Calver has been using the same piston for 15 years successfully. Retrominis, I’m not sure…

Both are silicone rich, Calvers on average have 1/4thou difference between the largest-smallest piston, Retrominis; 1/2thou (bore will be matched to the piston anyway).

Any advice and real world experience greatly appreciated. I’m tempted to go with with Calvers based on the fact they have a good reputation and wouldn’t use the same piston for 15 years if they werent any good (and they're 100 quid cheaper).

 

Cheers, Oscar

 

 

 

[Spider]

Calver's pistons are just re-boxed (and high priced!) Hypertecs. They are a good piston, I've been using them for a number of years now, very happy with them.

 

<Edit: Looking at those from Retrominis, they are also Hypertecs.>`

Edited by Moke Spider, 31 May 2016 - 01:01 PM.

[ozz1]

Calver's pistons are just re-boxed (and high priced!) Hypertecs. They are a good piston, I've been using them for a number of years now, very happy with them.

 

<Edit: Looking at those from Retrominis, they are also Hypertecs.>`

I rang up Calver earlier and he said the hypertecs were a copy and that the ones from Retromini were different and that he hadn't seen them before.He was surprised they were squeeze cast as its an expensive process close to forging. Have you used them on a modified engine? Do the ring lands wear quickly? On the face of it the ones from Retromini sound better but I think i'll let reputation decide this one. Thanks for getting in touch

[Gr4h4m]

I have run the calver pistons, which I was told by Graham Russel they are the same as his. they have been given some serious abuse in my supercharged engine. I run mine with Ptfe buttons, I would suggest you would too if your hitting those rpm's?

GR gave me his word if I melted a set he would give me another free, even if I got them from calver! I took him on his word and handed the cash over, he said he's used them at 10:1 on a supercharged engine and they have survived.

I guess it's always a gamble when the engine is pushed hard.

[OzOAP]

Save up for a bit longer and get the Omegas. I've used loads in Mini 7's, rally and fast road 998's and even in a supercharged 850. Nice thin rings, proper wire circlips. No problem with high compression and revs.
202 head? Miglias would have run pocketed block with 940 casting.

Edited by OzOAP, 31 May 2016 - 08:35 PM.

[Spider]

 

Calver's pistons are just re-boxed (and high priced!) Hypertecs. They are a good piston, I've been using them for a number of years now, very happy with them.

 

<Edit: Looking at those from Retrominis, they are also Hypertecs.>`

 

I rang up Calver earlier and he said the hypertecs were a copy

 

Funny, since Hypertecs have been around for some years before Calver's popped up. A couple of years back a mate had a set of GRs pistons analysed (which are the same ones Calver's selling) and found them to be the same piston.

 

I would guess Claver would say that the Hypertecs are a copy as he'd be loosing out on his mark up. These pistons in a Hypertec Box, retail here for less than 50% the price of Calver / GR Boxed item, so would Hypertec be loosing money on each set they sold?

 

By the way, Hypertecs are made by Rightway in Taiwan.

 

I've used them (from a Hypertec Box!) and found them surprisingly good. These are what I use in most builds I do.