1800 8v with Nissan pistons.

[bert308]

Having read somewhere about some Nissan pistons suitable for our boxers, I started looking in this catalogue:
http://www.wiseco.com/Catalogs/SportCom ... atalog.pdf
(note Wiseco offers 88 mm forged pistons for our 16v boxers and not really expensive if you search the part nr you'll find USA sellers)
I found suitable pistons page 68, they are for the Nissan KE24DE engine as found in anonymous sedans and pickups that I don't think we appreciate here in Europe, but I think we know the 240SX.
Anyway they are normally 89mm with a compression height 1mm lower than the 1700 boxer 8v pistons. And the piston pin is the exact same 21mm. This is the Wiseco catalogue but I wouldn't want/need forged pistons as they are stronger but not lighter and piston clearance at cold engine needs to be greater and they make more noise then until they reach operating temperature. I searched Nissans forums and standard cast pistons are supposed to be good for 700HP in aftermarket turbo applications. So I looked for a set and found them at ebay, very cheap, here is were I got them from:
http://www.ebay.de/itm/200949279274
Only us$106 for a set with new rings&pins! With shipping and duties they cost me Euro 120 delivered at my door. And I researched the NPR brand, they are good and an OEM supplier, economics of scale probably make the low price possible.
Some pics of the pistons and compared with a 1700 8V boxer piston.

Despite being larger, they are also 40 grams lighter and the pins are 10 grams lighter (bigger inside hole)

Fits an Alfa rod like it belongs there:

So now soon I'll take the pistons and some worn 1700 block to my local machine shop and have them bore the block for the 89mm pistons. With a 1700 crank this will give 1800 cc.
For the brave amongst us, the pistons are also available in 89.5 and 90 mm for the same price, but the general consensus seems to be 89 is the limit for dependable long time use in the Alfa boxer.
Now the compression height is 1mm lower and the chamber in the piston is about the same size as the Alfa piston. I have a very nice set of 1500 105hp "flat" heads (including good fast road C&B) that are flowed and enlarged for 40mm carbs, better in and out channels than the regular 1700 8v heads with chamber in head. The flat heads will more than compensate for the 1mm less compression height from the Nissan pistons, maybe the CR will even be too high, I'll have to measure. Another possibility is use regular 1700 heads that are 1mm (or a bit more) shaved.
So what do you guys think, this should make a very good 8v boxer. I will keep you updated as there is progress but this is a side project without time pressure.

[Veesix75]

Excellent, thanks Bert, interested to see the results.

[vecchioalfa]

This looks very interesting, think I will order a set

[bert308]

What to do about the headgaskets, the regular 1700 ones are 88 mm diameter, too small. I thought to be smart and would get a pair of Nissan gaskets and cut to size, retrim the holes for headbolts etc., but looking at pics they don't have the coolant passage between cylinders. Need to find some car with 89-91mm pistons and same cylinderspacing as the Alfa, difficult... Otherwise order custom gaskets from for example http://www.cometic.com/custom-gaskets.aspx
Copper is also an alternative and can be made at home but I prefer regular MLS gaskets for dependable street use.

[vecchioalfa]

Yes head gaskets could be a problem unless enough of us do this and we could look into a group purchase. As we are only talking about 1mm difference a gasket manufacturer may be able to modify a standard 1.7 head gasket by carefully removing the existing compression ring and fitting a new ring 1mm larger diameter, the compression rings are only crimped on I think but obviously you need the right equipment to do this type of thing

[bert308]

I received a PM from a member, here it is with my reply:

I used standard 16v gaskets in my 1800cc engine.
THe bore of the copper gasket is bigger than the original cylinder bore, somewhere around 88mm. The top of the piston is chamfered, or shaped at the top so that it is not a constant dimeter at the very top (of the piston), there is a step and the crown sits within the overall diameter of the piston. I did a number of dry fits after asking others what they had done when needing head gaskets for 89mm pistons - and they all said the same thing. Use standard gaskets after checking things out.

I hope that helps.

E.

Thanks E. I noticed the pistons are smaller diameter at the top, a used gasket will barely fit over the piston top. But I don't think it's possible to have a machine shop bore the cylinders with a taper at the top, the cylinder will still be 89 mm all the way and part of the gasket will be in the cylinder exposed to the combustion. Maybe there are some brands of gasket that are a bit bigger than the one I have here (Reinz). It is good to hear some used standard gaskets without problem. I will investigate further.
I will post this info in the thread so others can read and offer comments.

[junior]

Hi Bert 308.

Your info and pictures have been most helpful as struggling to make decisions with my engine.

The original advert is sold out but E bay no's 151171854584 and 191156654195 are very similar and a good price.

http://www.ebay.co.uk/itm/151171854584? ... EBIDX%3AIT

http://www.ebay.co.uk/itm/220426320325? ... EBIDX%3AIT

Hope the links work .

Has anyone got any further with fitting these pistons and overcoming the gasket problems ? Thanks Junior

[AlfaCorseChris]

This is great news actually !!!

Brilliant find ! Love it !!!

What I would like to see though, is if we could find matching piston rods from another/more powerful engine, that would fit the boxer blocks without issues on the crank

Anyone got anything in mind ?

[PETROLHEAD]

You don't want much do you Chris? lol!

[bert308]

I think our boxers have short rods in order to not make the engine too wide. But they are strong enough as there is never a problem with them? There is a Chinese supplier of H-beam rods and they make them for a lot of applications. Don't be put off by the Chinese origin of the rods, I have a set for my Lancia 16v turbo engine (meant for the Montecarlo) and quality is superb (ok, by just looking at them) but there are no complaints found on the web and they are sold everywhere in large numbers, I only paid 200 euro + shipping form Germany. They seem to have a fairly standardized production process and seem to make rods in any size just by entering the numbers in their machining, but non offered for the Alfa boxer though. Not sure if they would make a batch for a group buy if we specify length and big and small end diameter...
Link to these rods (but found them for less elsewhere) www.ebay.de/itm/181043038744
Didn't realize this thread is that old already but just past week I dismantled a 16v block and it is ready to take to the machine shop, together with a pair of heads that I put new valve guides in and have new valves for. I will let them, besides boring the block, surface the block and heads to have a clean base for maybe copper head gaskets, or I will try regular 87mm gaskets first.
I'll use a 16v block because of the oil sprayers in the main bearings. Also the 16v has a bigger oil pump and hardened crankshaft, though that could be transferred into an 8v block.

[junior]

Hi.

Did not realise they had a larger pump.

Do you know yet exactly what your going to bore the block out too ? Would be very interested in your decision.

I am having a 8v done but rather concerned at boring out too much and cracking the block under use.

I believe it was often a problem in the day and these parts are sadly not improving as time goes on.

Thanks

[PETROLHEAD]

you should be quite safe taking a 1712 block to 1800, and a tad more (89mm Pistons)

its when you start to stretch above 89mm that the block cylinder walls can come into question, so if done correctly, you should be good to go.

[Johnboy]

Yeah 89mm Pistons are the way forward

[bert308]

I once drilled holes in an old block to check cylinder wall thickness here and there and thinnest I could find was 5.5 mm. It will be 4.5 once bored. That was a 1700 block. I also measured an 1.5 block and wall thickness was also 5.5 mm! Different casting. That is why boring an 84mm block to 87mm to use 1.7 pistons would work but not such a good idea.
Final bore size? I will take the block and pistons to the machine shop and tell them the Alfa manual says 0.03-0.05 mm piston-cylinder clearance and let them handle it.

[PETROLHEAD]

Thats the way!

because you're using a different brand of piston and rings though, i would take the rings in aswell to progressively check ring gap as you get close to the piston clearance tolerance range

[junior]

That all sounds very reassuring. Thank you chaps much appreciated.

[Jan Sud DK]

Hi all , what about the bottum end of the piston , its much wider than the original ?? (Berts pic 3 from the top) are you sure that it wont be a problem ? And why is the Alfa piston shaped like that then ...

[adsblacksud]

Off topic but do any of you catalogue demons know if there a similarly low priced version suitable for a 16v?

Not that I'm going to look at it now (too close to getting the sud finished with its existing engine) but I have a spare 16 valver that apparently has been "worked on" that I'd like to have a play with next winter.

Thanks

Adam

[bert308]

What do you guys think of these? I already have a set of this brand for a Lancia and quality looks perfect and i couldn't find complaints about them on the net.
http://www.maxspeedingrods.com/nissan-c ... onrod.html
Sud rods are 129mm so these would suit the Nissan pistons with 1 mm lower compression height perfectly as they are 130,2 mm long! Big end is 53mm as compared to the Alfa 54 mm but the crank is also 50 mm so you would also have to use the thinner 1.5mm Nissan bearings instead of the 2.0mm Alfa. Only need to find out if the big end width fits our cranks?

[PETROLHEAD]

This sounds like an incredible plan bert,

excellent homework, and thank you for sharing it all, marvellous!


as for the rods, like you, i've only found good things to read, but i don't know anyone personally using them right now to speak too.

quality appears very good, and if they are up to the claimed spec, arp bolts etc, i can't imagine there being any problem, but put together the reality that they are a new H beam, not a 30 year old stock item, and i think that's probably enough! lol!


Keep it coming Bert, its all good.

Have you considered what compression this set up will result with?

[bert308]

Hmmm, I would have ordered a set of these but the Nissan rods seem to have a 26.8 mm wide big end, Alfa only 24 mm so these rods would have to be machined down including the bearings something I wouldn't attempt with my trustful grinder and it's all I have. It maybe can be made to work but I hope someone else is braver and orders a set and I will watch how it goes

[bert308]

Handy rod catalogue with all data here, also available as excel file:
http://pauter.com/parts/technical/conne ... d-catalog/

[junior]

Hi In case anyone else is trying this tactic. Keith of K& N is working on my engine and has tried to fit the nissan pistons after boring the block and skimming it, sadly they CLASH when the opposing pistons are at their lowest.

So a lot of money spent, but no result ! Could take material of the bottom of the pistons, but would end up very close to the gudgeon pin.

Gutted.

[PETROLHEAD]

Hi In case anyone else is trying this tactic. Keith of K& N is working on my engine and has tried to fit the nissan pistons after boring the block and skimming it, sadly they CLASH when the opposing pistons are at their lowest.

So a lot of money spent, but no result ! Could take material of the bottom of the pistons, but would end up very close to the gudgeon pin.

Gutted.

That has been the issue with other sources of pistons before, and as you've found, the only method of curing it is to remove the skirt right up to the pin and clip area.

It can be done, but it gets scarily close to safety concerns as i understand it.

Unfortunately, once you've added a load of costly engineering into it, it can start to resemble the sort of prices for a set of Forged pistons made to fit our engines, and a whole lot quicker.


just how close would they have to go?

[junior]

Oh, I was not aware of that.

Not sure how much lee way there is exactly as the phone call was at a bad time but will catch up with Keith on monday and find out.

He does not feel happy about it as there would be so little left. much as you describe I guess.

Not sure what to do now. Thanks for your comments though.

[PETROLHEAD]

Like i said, it can be done, and from what i gather, it was rather scary to look at, and quite expensive to have done correctly and then rebalanced of course, but i believe it was done and ran successfully in the end.


Keith, if it hasn't already, would do well to discuss it with Tom, BLS.

[sudboy1490]

I did wonder if there might be some big clearance issues with these nissan pistons Junior. There's a whole world of difference in the back of the nissan ones when you look at them compared to the standard alfa ones. I even had problems with some 80mm pistons i bought for my 1.3 rebuild a couple of years ago. As they weren't original alfa or i guess a reputable make it turned out that there was too much metal inside the piston which meant there wasn't enough clearance in the back of the piston to clear the opposing big end bolt when the pistons were at the bottom of the stroke. Unfortunately the original engine builder hadn't realised and it had to be stripped again this year and some metal removed from the inside of the pistons to give the clearance needed.

Fortunately it was only a few mm's that needed to be removed and not a whole lot like these nissan's are going to need. Shame though, it would have been a fantastic cheap alternative to forged pistons!

col

[junior]

Well that has answered my next question and Keith has been talking to Tom so It is one route I could take.

In fact it seems the only route having gone this far. I do not fancy buying yet another engine.

Thanks again.

And thanks Sudboy, your now making me look at the photo's in a new light. Will let all know how I get on.

[junior]

Hi Has anyone got any further down this line for using these pistons or similar. I have been trying other routes, having pistons made for the block I have, but badly stalled now.
Any thoughts appreciated.

[bert308]

I never realised the extra skirt on the Nissan pistons could be a problem, attached is a pic of the conflict. I guess the pistons should be modified to be like the Alfa pistons.
I also ordered a set of the Max Speeding Rods for the old Datsun Bluebird 1.8 as mentioned earlier, they were suddenly on their site for only $169 so I ordered but then they didn't want to sell for that price and had to pay $239. They will need narrowing on the big end side though. I will take the whole lot to the machine shop soon.