Building an engine, what base?

[Martin.]

So when Mike fitted my ARP rod bolts he advised me that my big end bearings were really worn. I didn't take any action there an then because I was off the the ring that weekend.

Now the winter is on it's way I'm planning on sorting something out for the engine. Either rebuilding what I have currently or starting a slow build on the side. Really not sure what route to take just yet as I'm unsure of any differences or costs.

If I was to go down the route of building up an engine slowly on the side, what would be the best base to start from??

Any old scrap engine and replace/refresh everything so it's all mint. Or get a second hand 172 cup engine and go from there with the same plans?

172 cup engines seem to be strong to start with from what I've read, or will that not make any difference if I'm getting one built up to new from a scrap one anyway??

Basically if I'm going to be doing this I don't want to have to do it again! So buying any old second hand engine and whacking it it hoping for the best is not an option at the minute.

I don't think I want any high comp pistons or any forged parts, that would be too much expense for what I'm after. Especially if something goes wrong and these need to be replaced!

So I'm thinking just a standard ish engine with some reliability parts. Big chunky bearings, ARP rod bolts, one piece valves and anything else similar etc.

I've already got 438s to use and Jenvery ITBs now. Although I am considering selling the 438s and changing to something more suited like 421s whilst I'm at it...

Again, if I'm doing this I don't want to have to do it again, not for a long time at least lol.

So does anyone have any suggestions or opinions to offer?

My main question is what are the pros and cons for rebuilding/refreshing my current engine compared to getting a donor engine and doing it on the side?

Also, if I did get a donor engine for work, what would be the best base to start from?

Cheers.

 

[mantis946]

What sort of budget would you be looking at ? I've recently started doing the same and once you tot up the cost of all the part's it's not cheap even all standard !

Engine dynamics do a few DIY rebuild kit's
http://www.engine-dynamics.com/DIYEngineBuildKits/cid297/DIYEngineBuildKits.asp

 

[Headline Sport]

Hi

With these kits, if you are going to the effort to put in new rings/piston/bearings... would you have to factor in a cylinder rebore and crank regrind?

Thx

 

[Martin.]

What sort of budget would you be looking at ? I've recently started doing the same and once you tot up the cost of all the part's it's not cheap even all standard !

Engine dynamics do a few DIY rebuild kit's
http://www.engine-dynamics.com/DIYEngineBuildKits/cid297/DIYEngineBuildKits.asp

Yeah I did take a look at their builds, one or two of the options do tickle my fancy, they are VERY well priced too. They're just a bit too far from me, I mean it is do able, it's just a long way. It is an option though. Might call Andy at some point and discuss a build price for what I want.

Hi

With these kits, if you are going to the effort to put in new rings/piston/bearings... would you have to factor in a cylinder rebore and crank regrind?

Thx

I will probably be getting a crank regrind yeah. Thought I mentioned it but must have removed that sentence when I was editing it. Unless another good second hand crank seems a better option.

Didn't think about a cylinder rebore though, wouldn't that require different sized pistons?

 

[Chip-mk1]

I dont believe the cup engines have any advantage.

Personally I would avoid reground cranks, better to just find a good nick standard one as you take the surface hardening off when you grind them and end up on thicker bearings.

Im a firm believer in building an engine from the best condition donor possible, a couple hundred quid extra to start with good condition parts in the first place seems like money well spent to me to avoid having to do things like grinding a crank etc, and especially if you are going to be re-ringing on original pistons, why start with more worn bores than you have to?

 

[Ph1 Tom]

What management have you got?

 

[Martin.]

Yeah I get your point Chip-mk1. Finding a good donor engine is also very hard in the first place though isn't it, no idea what condition it's in until it's actually taken apart. Could end up paying top money for a 'good' engine to find out it's just as worn as mine if not more. If that makes sense..

I didn't know there was any problem with getting a crank re ground though?

 

[Martin.]

What management have you got?

OMEX 600

 

[Martin.]

What's the Benefit of forged pistons? Lighter and stronger?

 

[SharkyUK]

What's the Benefit of forged pistons? Lighter and stronger?

Forged pistons are often heavier and denser (than cast pistons) but can be run harder as they are more tolerant to extreme heat, pressure and detonation. Generally, they are more durable and stronger due to the way in which they are manufactured. I also believe they are easier to work with and customise for high-performance applications.

Of course, there are also cons as well as pros.

(I'm no expert, this is my understanding having done a bit of reading about them before going forged with my engine build). /disclaimer

 

[Martin.]

Cheers mate. What about price difference? If one melts how much to replace etc?

 

[...]

how much is a short engine for these from renault ,

what i used to do with zetec engines was buy a short block and work from there with a head that was going to be ported and uprated etc , so top end was bespoke and bottom end stock then modded .

 

[Chip-mk1]

Not sure if renault will sell bottom end only, but its around 2.5K for a new bare engine (ie no manifolds or anything)

 

[Chip-mk1]

Forged pistons are often heavier and denser (than cast pistons) but can be run harder as they are more tolerant to extreme heat, pressure and detonation. Generally, they are more durable and stronger due to the way in which they are manufactured. I also believe they are easier to work with and customise for high-performance applications.

Of course, there are also cons as well as pros.

(I'm no expert, this is my understanding having done a bit of reading about them before going forged with my engine build). /disclaimer

Actually in terms of heat, the melting point isnt generally any higher on forged, hence if you go lean you can still melt the pistons more or less as easily (they actually conduct slightly better from being denser so can slightly better send heat down into the oil, but it really is a small effect).

They are MUCH stronger though, and wont fall apart on the ringlands from a tiny bit of detonation or just from fatigue like the standard ones can.

Downside is they wont cover as many miles as they expand more so have to be installed looser.


So think of them as suitable for heavy short term use, as opposed to light long term use.

 

[...]

ford was about 1700 at the time for a full engine , but a short block could be had for £500 new , obviously you will realise why the top end was pointless to have new although i did on a later one but that was down to a totalling of the engine (nowadays i always wire lock oil filters on !!)

 

[Martin.]

Downside is they wont cover as many miles as they expand more so have to be installed looser.

So think of them as suitable for heavy short term use, as opposed to light long term use.

Not for me then I don't think. I'd ideally like a reliable engine that'll happily last me a fair few years.

The thought of getting rebuilds puts me off because I can't do it myself.

 

[The Fatty]

sounds like a sensible build. I would go with arp bolts and one piece valves personally. You can get a good OE secondhand crank, so provided your bores are ok on the existent engine, I guess the real question is 'do you want to be driving the car whilst you work on the engine'? if not, then use yours.

 

[Martin.]

sounds like a sensible build. I would go with arp bolts and one piece valves personally. You can get a good OE secondhand crank, so provided your bores are ok on the existent engine, I guess the real question is 'do you want to be driving the car whilst you work on the engine'? if not, then use yours.

Yeah ARP rod bolts and valves are already a must.

I don't use the car on the road and have access to another car so doing the work to my current lump is no problem at all.

With a second hand crank though, what stops me buying it and then finding out it's actually worse than mine lol!?

 

[bozothenutter]

Actually in terms of heat, the melting point isnt generally any higher on forged, hence if you go lean you can still melt the pistons more or less as easily (they actually conduct slightly better from being denser so can slightly better send heat down into the oil, but it really is a small effect).

They are MUCH stronger though, and wont fall apart on the ringlands from a tiny bit of detonation or just from fatigue like the standard ones can.

Downside is they wont cover as many miles as they expand more so have to be installed looser.


So think of them as suitable for heavy short term use, as opposed to light long term use.

is there an option to go non forged but just better quality?

 

[Chip-mk1]

is there an option to go non forged but just better quality?

Im not aware of an off the shelf option for the 172, you could get some good quality pressure cast ones from someone like Mahle, but you'd probably need to buy 10,000 or so for them to be sensibly priced.
Forged though are cheap and cheerful to make in small numbers.

 

[The Fatty]

With a second hand crank though, what stops me buying it and then finding out it's actually worse than mine lol!?

check it first? or buy it from someone reputable on here?

 

[Chip-mk1]

Not for me then I don't think. I'd ideally like a reliable engine that'll happily last me a fair few years.

The thought of getting rebuilds puts me off because I can't do it myself.

Trouble is the standard ones are such poor quality that if you get unlucky they could fail on the ringlands almost straight away on a tuned engine if there is an airpocket in the wrong place (the standards are full of them as they are such cheap litter)

 

[Martin.]

Trouble is the standard ones are such poor quality that if you get unlucky they could fail on the ringlands almost straight away on a tuned engine if there is an airpocket in the wrong place (the standards are full of them as they are such cheap litter)

Arghhhhhh things are never easy for me lol!!

How much do forged pistons cost roughly? How much life would you expect to get out of them? If I could get three years of trackdays without any problems then I guess it's an option.

Never heard about any problems with the standard ones before, thought these engines were meant to be bullet proof lol.