Broken piston after 343k kms(rebuild help)

No its just the opposite

Costa...........more volume = lower cr = more boost........but there's only so far you can go before the start of injection/ignition becomes so finite that the fuel will not combust........this is why i now have my glow plug ignition on a manual switch for really cold conditions for one.

mojogoes said:

Costa...........more volume = lower cr = more boost........but there's only so far you can go before the start of injection/ignition becomes so finite that the fuel will not combust........this is why i now have my glow plug ignition on a manual switch for really cold conditions for one.

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More volume = more volume to compress... so higher CR.
This was what I was thinking...

Also going from 79,5 to 80,5 will lower the CR ?

So more volume same stroke = less CR ?

I have a stock head gasket ... should I change for a thinner one or is lower CR better for my setup?

Regards

afn rods are 159mm long or 144mm?

see rosten rods to use pd150 pistons with wrist pin 26mm an 50,6 crankshaft

a junta de cabeça escolhes quando medires a altura do piston no tdc em relaçao ao bloco se tiveres duvida nisso mandote bonecos para veres que é mais facil

choramix said:

a junta de cabeça escolhes quando medires a altura do piston no tdc em relaçao ao bloco se tiveres duvida nisso mandote bonecos para veres que é mais facil

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O meu mecanico vai manter a stock de 3 moscas.... a minha duvida era se meter uma de 2as moscas tem alguma vantagem para aumentar a compressao.

Cumps

ArturCosta said:

Wow very nice pdf

About the CR... it will become higher since there is more space to fill... isnt it?

Click to expand...

Nop
OEM 19-1 ....now will be something like 17-1 ,I think ...
Is better for higher Hp

Keep on going

ArturCosta said:

O meu mecanico vai manter a stock de 3 moscas.... a minha duvida era se meter uma de 2as moscas tem alguma vantagem para aumentar a compressao.

Cumps

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Não Costa ,é ao contrario...3 moscas é o mais usado já mesmo para baixar as CR´s...Nos gasolinas NA´s é que se comprime !

Ao criares mais volume de combustão vais ter uma taxa menor,é esse mesmo o objectivo
Em medidas OEM 79.5 por ex,já andei com 1mosca e 3 moscas...nota-se mesmo o enxer do plumão na de 3 moscas...ou seja nm´s ao poder

Esses Piston são mesmo pra AFN/AHU ou para outro motor?É que no caso dos 81 da transporter teem que se fazer uma alteração num dos lados da camisa do piston por onde passa o jacto de lubrificação oleo...ou seja teem lados opostos,teem que se abrir novo rasgo no da transporter!


O Choramix é crack...tambem me arranjou uns bonecos para fexar o meu bloco e não so...teve que tambem meter a unha hehehe
Esse motor teem muitas manhas...cuidado!


Comprimentos do JZverde

Silva said:

Nop
OEM 19-1 ....now will be something like 17-1 ,I think ...
Is better for higher Hp

Keep on going

Click to expand...

Please use your brain.. there antoher topic where I must have said more than 10 times how it worked before people were actually understanding it..

Increasing the bore without touchin anything else will INCREASE the compression ratio, but probaly the bowl will have a slightly larger volume..

So where do we "stay"?

Im I raising the CR or lowering?

Silva: O meu mecanico ja montou mtos destes motores , foi mecanico da VW/Audi mto tempo logo n vejo qq problema ,agora ele disse que o CR ia aumentar e n reduzir.

So what is actually the compression ratio? If it is the relation between the air at BDC and TDC then the CR should be the same since at BDC there will be more air but at TDC it will have the same compression and also same bore...

I just think im out of fuzes today lol

Regards

Quote.........

Up to this time, the higher compression rations have been widely used in high speed diesel engines, but a lower compression ratio is demanded to achieve an increase in output with special regard to the stress of structure, engine noise etc. In this paper, some problems arising from the reduction of compression ratio in diesel engine were first described, and the basic data required to derive a low compression ratio in diesel engine were first described, and the periments, it was shown that the most important problems with low compression ratio are the reduction of maximum output and the increase of specific fuel consumption and this depends rather on the increase of cooling loss than on the reduction of theoretical thermal efficiency considering the rate of heat release in cycle. In the engine noise, the lower frequency part of sound pressure was reduced while, on the other hand the higher frequency part increased at a lower compression ratio. Consequently the sound pressure level of the overall range increased. In addition, the higher frequency part seems to be affected by the maximum rate of pressure rise regardless of compression ratio.

You have a tipical way of not answering my questions

I just asked what is CR.

In this engine if you put in 1000cc of air at BDC you will have 51cc at TDC... is this correct?

Rub87 said:

Please use your brain.. there antoher topic where I must have said more than 10 times how it worked before people were actually understanding it..

Increasing the bore without touchin anything else will INCREASE the compression ratio, but probaly the bowl will have a slightly larger volume..

Click to expand...

So what?
Are you god?

I now that,and dont have brain...do you have brain?Good for you Rub lets help Artur to find is Cr´s now! heheheheheheh



Artur encontra o virtual engine calculator na net,é gratis,caso não eu tenho.

O melhor a aplicar é mesmo Oleo pra dentro da camara com o Piston no TDC,teem que ser muito minusionso,tens de ter uma seringa graduada e saber quando esta preenchida a camara para retirares o oleo e depois sabes quandos cc de oleo levou.
A seguir vem a conta caso percises ajuda ou resolves no programa ou fazes a formula,que suponho que deves saber quais os valores necessarios para alcansar o valor final!

Em relação ao teu mecanico dizer que o cr ia aumentar....ou existe falta de comunicação ou ele é um ganda maluco lol no bom sentido

lolo alargando o cilindro nao vai aumentar a taxa de compressao

mas se ha duvidas faz pela formula de calculo da taxa de compressao que nao te falha

o silva ja me tirou as palavras

o silva ganda maluco hehe

e isso so da com a junta e a cabeça apertada.
p.s boa sorte ai com a a4

ja reparei q espetaste a caixa ajm que te tinha falado na altura

choramix said:

e isso so da com a junta e a cabeça apertada.
p.s boa sorte ai com a a4

ja reparei q espetaste a caixa ajm que te tinha falado na altura

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Sim , acabei por esconher a caixa muitio pela info que me tinhas dado , pq
resconstruir n tava a dar e apareceu esta cm pai 30mil kms ou menos e pronto foi logo

About the CR , it will become lower I understand but it will be a very small difference I guess.
The engine will go from 1986 to 1920cc... same stroke but more bore.

Well, I also mailed a company to ceramic coat my exhaust manifold... Im getting tempted to do it

Hope to have more news about the cam tomorrow.

Regards,

No I'm not god, only for the girls I am, lol :// I wish

So I was saying, if you increase bore without increasing bowl volume you CR will raise , think about it, at TDC the volume in the bowl is the same as in BDC, but the volume in the the cilinder is at TDC ~0 while at BDC you have ~0.1l more due the increased bore..

if you read on from post 81 here you'll see why I told this.. didn't want to run into the same discussion again http://forums.tdiclub.com/showthread.php?t=219187&page=6&highlight=bowl

Ok lets end this discussion now:

This are all example values...
79,5cilinder= 474cc (at BDC)
79,5cilinder= 24,3cc (at TDC) thats 19,5:1 CR

80,5cilinder= 480,5cc (at BDC)
80,5cilinder= 24,6cc (at TDC) that would make 19,5:1 CR.. but it will have more CCs at TDC since it has more at BDC and stroke is the same.

So lets imagine 25cc at TDC that will make a CR of 19,2:1 so here the lower theory is correct.

Lets now add the bowl to the math:
Bowl= 20cc
79,5cilinder= 494cc (at BDC)
79,5cilinder= 25,3cc (at TDC) thats 19,5:1 CR

Bowl = 20cc
80,5cilinder= 500,5cc (at BDC)
80,5cilinder= 25,6cc (at TDC) that would make 19,5:1 CR

Now the bowl is giving 20cc more to both but the CR will also be lower.

By this math the cilinder head has 1,225mm more less... so in my case the CR will be nearlly the same!

Can anyone help with the math? Have I got anything wrong?

Lets move on...

Im thinking on installing a TDI130 intake manifold. Is it any better?
I looks like its bigger then mine.

Regards

Still your maths are off.. where did your bowl volume go at tdc? if you want it easy to understand, imagine the ideal situtation were squish volume is zero, than it's easy to understand that increasing the bore while keeping the bowl unchanged wil increase CR..

I don't say it will increase in your case, but I just want to say clearly that increasing the bore alone will not drop the CR..

and yes, the PD130/150 intake is a good upgrade over stock, I experienced a good noticeable drop in soot output when changing the crappy stock intake to an intake with decent plenum volume and equal flow distribution...

Rebuild finally started!

The pistons where installed yesterday... havent seen it yet but hope on monday have more info.

Cam hope it arrives this week...

Take some pic's Costa while its all apart........did you have the head skimmed just as a precaution.

mojogoes said:

Take some pic's Costa while its all apart........did you have the head skimmed just as a precaution.

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Yes the head will be skimmed as far as I know.. althought it was ok it ran 343kms ... it was "closed" for 12years

I did not take fotos of it all apart... the old parts. But I will take of it beeing rebuild... I really love the look of the pistons before they get full of diesel

Pop tested at 230/310bars ... very nice diesel injection shop I found, for 60€ installed the nozzles and tuned both pressures

Now only the Cam missing... engine will probably have fotos of it today.

Regards

So the block arrived yesterday ... here are some pics of the parts ready.

Block , now a 1,925TDI



The head , no porting made yet.



Here are the rods ready too



Sad that the cam is missing or it was going to be put together this weekend.

Regards

When you get it back together, try to keep the engine speed down if you can. That will put a lot less stress on all your rotating parts.

Redputter said:

When you get it back together, try to keep the engine speed down if you can. That will put a lot less stress on all your rotating parts.

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The engine will run at idle for 1day more less... then I will be gentle in the first 500kms of the engine

From what I have gathered thats absolutely the wrong way to brake it in. You should avoid idling it and stress it some when driving. No full throttle to the 250kmh stressing but some decent load on it with different revs.

BTW. some say that using good synthetic oil during the brake in period is a bad thing because its too slippy and the parts dont settle in that fast with it.

Take the car out for a spin and just drive it around like a granny until its wormed up and then give it a few blasts here and there.