RX7 engine life and rebuild costs ?

But surely turbos are separate from the main engine?

I'm not familiar with rotary engines. What parts require replacement at overhaul time? In the same way as the basics would be a rebore and new pistons and a crank grind and new bearings on a conventional unit - as a minimum?

Reply to
Dave Plowman (News)
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Cylinders?

Reply to
Ian Dalziel

Ok, 'combustion spaces'.

Reply to
:::Jerry::::

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Timo Geusch" saying something like:

I'll be getting acquainted sometime soon with the mad world of whizzy bits in the RX lump I have. Rather, its successor - I plan to rebuild a

13b lump to higher output than standard and then slot that in to replace the 12a engine I currently have.

That was the plan, until I found that seal kits alone were around the

750 pound mark. Bugger that.
Reply to
Grimly Curmudgeon

Try saying "swept volume." It's the difference between the maximum and minimum volume in the combustion chamber. In a rotary, you could argue that there are three pistons working the same combustion chamber and so the swept volume (i.e. cc) is one third of the equivalent piston engine. IIRC, the Inland Revenue knocked that one on the head

25 years or more ago.
Reply to
Dean Dark

Well, didn't they reshaped the ports to help with rotor tip wear which meant they work well with turbos? Rather than the turbos being the issue? There were lots of NA RX7's and RX3's and they all needed the same sorted of maintenance schedules.

Reply to
Sleeker GT Phwoar

correct

Are you talking about rotary or reciprocating engines, seeing that both have a 'swept volume'?...

Reply to
:::Jerry::::

Precisely. I was just bringing up the old argument about whether or not to multiply a rotary's swept volume by three to determine its capacity.

Reply to
Dean Dark

In message , Dean Dark writes

Yup, and the reduced road tax for small engines doesn't apply to rotaries. Shame really, the irony of getting cheap tax for running an "environmentally friendly" RX-7 would be delicious.

Reply to
Steve Walker

You can't even spell the word.

OK, dwell is important, and it's particularly awkward for an engine with separated ignition systems. Dwell variation between them gives rise to timing jitter and dwell is always more significant on an all-mechanical system, rather than even one with a simple amplifier

But why does that improve _reliability_ in a Wankel ?

Reply to
Andy Dingley

Yes, but my point was that you can't really compare this type car with a run-of-the mill Beemer.

If you're lucky and the rotors aren't damaged in any way, you're looking at seals (lots of), potentially rotor housings if the surfaces are damaged, plus some machining of the sideplates if necessary.

Plus of course the tip seals, which aren't exactly cheap and can cost up to a grand, depending on the spec you want.

Reply to
Timo Geusch

Sorry, I should have been clearer - the turbos are harder on the engine and do shorten its life, especially if some kack-handed "tuning" has been involved.

The older NA RX-7s did last longer than the turbo'd ones for exactly that reason, and that was before Mazda squeezed between 250-280PS out of essentially the same engine.

Reply to
Timo Geusch

Ouch.

Reply to
Dave Plowman (News)

FMR !

So how much (roughly) is the raw cost of a "seals, gaskets and consumables" package for a minimal rebuild ?

Reply to
Andy Dingley

Not sure about the gaskets, but a basic set of rotor tips is considerably cheaper - I'd still budget something around 750quid for the parts at least, and that's only if it doesn't need anything else.

Oh, and unless you fancy disconnecting and correctly reconnecting an insane number of vaccuum tubes I'd farm out the job...

Reply to
Timo Geusch

Only a fool would even consider a minimal rebuild....

Reply to
:::Jerry::::

The purpose is to give a baseline of the costs.

This "3k rebuild" figure sounds expensive to me. Now if that's an ultimate rebuild but a workable one can be done for 1k, then that's quite a different picture to if the simplest possible rebuild costs 2k5 anyway.

But then you just post to provoke arguments, not to communicate, don't you.

Reply to
Andy Dingley

Fair enough. But in many cases, the life shorting is down to people not knowing about the proper way to shut down a turbo car properly, particularly an older one, and as you say, "tuning".

Reply to
Sleeker GT Phwoar

I thought I knew about cars until I had a turbo CA20 engine. Shutting down procedure was not detailed ANYWHERE in the car's documentation, or in Haynes manuals covering the Nissan Bluebird which also uses that engine. So why? Do the manufacturers think it will be ignored, or are they looking forward to the replacement charges?

Reply to
Andy Luckman (AJL Electronics)

So what you really need to know is the cost of parts @ the MRR price, plus the average time a rebuild takes in the hands of someone who knows what they are doing, you can then decide if the quote have is expensive or not (bearing in mind that labour costs will be different depending were you are located).

No, as I said, only a fool would consider a minimal rebuild. You could spend 1k on a rebuild and then find the whole lot goes 'bang' again due to something you cheap-skated on, result is that you end up spending 3k anyway on top of the 1k you wasted...

Reply to
:::Jerry::::

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