Audi TT Forum banner
1 - 20 of 28 Posts

·
Registered
Joined
·
1,765 Posts
Discussion Starter · #1 ·
Just trying to see what sort of builds people have done and maybe pick your
"BRAINS" as this is something im eyeing up myself so was considering what
would be a good setup for my needs :) ....

So this is the little bit i know

(For the people who dont know the crank creates a "stroke" is basically how far the pistons travel
up and down the block from the crank rotating)

Stock 1.8t Crank

Stroke 86.4mm

bore sizes for pistons 81mm 81.5mm 82mm 82.5mm 83mm

i think there is a bore size to 83.5 but people seem to go for 82.5mm or 83mm

and its 83mm is what gives a true 1.9ltr bore but allot seem to go with 82.5
not quite sure why ?

2.0t Tfsi crank

will give you a stroke of 92.8mm and combined with 83mm pistons
will give you 2008cc same bore size as the 1.9 stock crank but its the
TFSI crank what increases to the 2ltr because of the longer stroke

So hopefully i got that right ? :lol:

Anyway when it comes to pistons i "hear" lower compression pistons allows
for increased boost and timing but seems a few have opted for higher
compression pistons what may aid quick spool? this is what im after
is to enhance quick spool further with my hybrid at lower rpm so was thinking
83mm bore with higher compression pistons

what setups have you got Any thoughts ?

Sorry if i made a meal out of this question i was bored :lol:
 

·
Registered
Joined
·
1,765 Posts
Discussion Starter · #4 ·
Diveratt said:
Your maths looks right Smithy the only thing you left out was the ££££££ it's going to cost
Very true but if i stayed with stock crank would only need pistons as i got everything else labour
would be the most with engine removal and i can get a good 06a block dirt cheap what i
get built then drop in the garage for the transplant but your right £££ mounting up

V6RUL said:
Maybe increasing the capacity and keeping the stock turbo will give you the quickest spool.
Steve
Hybrid will spool but it seems to out perform the 1.8 at low rpm causing the surge issue
a very nice guy called Dan hybrid builder suggested about increasing bore to help with
this low rpm surge,,, i want boost from 2k rpm to redline with the hybrid :D
and then beef up the top end with nitrous :lol: ok getting carried away :)
 

·
Registered
Joined
·
11,542 Posts
Mine is being built with 92.8 crank and 83mm pistons =2008 cc.

Same crank with the following pistons

81mm=1912
81.5=1936
82=1960
82.5=1984
83=2008
83.5=2032
 

·
Registered
Joined
·
1,765 Posts
Discussion Starter · #6 ·
Matt B said:
Mine is being built with 92.8 crank and 83mm pistons =2008 cc.

Same crank with the following pistons

81mm=1912
81.5=1936
82=1960
82.5=1984
83=2008
83.5=2032
You know what matt i would love to go for TFSI crank but it gets to the point where
do i draw the line with these things you can just keep going and going :lol:

edit
how about 95.5mm 1.9L TDI crankshafts 2067cc of displacement with 83mm bore pistons
mind you dont think thats to straight forward either ...
 

·
Registered
Joined
·
1,656 Posts
The question is what kind of engine you want to build? Lower compression for max power and higher compression for better off boost performance.

Some want to leave the possibility to still make one more bore if something goes wrong and that's why they don't go for the biggest possible right away. Also depends how much power you are going to take from the engine, more power needs more meat in the block walls. Piston availability is also a factor 82.5mm and 83mm are both commons sizes on 1.8T stroker pistons.

Crank with longer stroke brings that grunt to off boost driving that 1.8T is lacking. If you compare 1.8T and 2.0TFSI the most noticeable difference is how much more grunt the 2.0TFSI has close to idle. TFSI technology plays apart surely, but also longer stroke. Same force but 10% longer stroke, gives 10% more torque, well at least in the point where piston is half way on its cycle.

I have 95.5mm crank from those more "powerful" 1.9 TDI engines, combined with 83mm pistons it will give 2.067L engine capacity. Crank has quite much extra beef, so if I ever use it I will first take it to machine shop for balancing and lightening. Will definitely use close to stock compression.

Just remember that all that power needs to fit out from this hole :wink:

 

·
Registered
Joined
·
11,542 Posts
nate42 said:
The question is what kind of engine you want to build? Lower compression for max power and higher compression for better off boost performance.

Some want to leave the possibility to still make one more bore if something goes wrong and that's why they don't go for the biggest possible right away. Also depends how much power you are going to take from the engine, more power needs more meat in the block walls. Piston availability is also a factor 82.5mm and 83mm are both commons sizes on 1.8T stroker pistons.

Crank with longer stroke brings that grunt to off boost driving that 1.8T is lacking. If you compare 1.8T and 2.0TFSI the most noticeable difference is how much more grunt the 2.0TFSI has close to idle. TFSI technology plays apart surely, but also longer stroke. Same force but 10% longer stroke, gives 10% more torque, well at least in the point where piston is half way on its cycle.

I have 95.5mm crank from those more "powerful" 1.9 TDI engines, combined with 83mm pistons it will give 2.067L engine capacity. Crank has quite much extra beef, so if I ever use it I will first take it to machine shop for balancing and lightening. Will definitely use close to stock compression.
Nice post Nate - I am looking forward to 2 litre spool :)

nate42 said:
Just remember that all that power needs to fit out from this hole :w

My hole is a bit bigger than that :)
 

·
Registered
Joined
·
1,765 Posts
Discussion Starter · #14 ·
Matt B said:
TT SMITHY said:
Matt do you know why people generally opt for 82.5 instead of 83-mm on stock crank ?
Not really sure mate but something to do with what pistons are avaliable and what you are aiming for.
Ok thanks matt :)

nate42 said:
Just remember that all that power needs to fit out from this hole :wink:
good point :lol: by the way great post :D
 

·
Registered
Joined
·
1,656 Posts
Matt B said:
Nice post Nate - I am looking forward to 2 litre spool :)
You had GT2871R right? I'm sure you won't be disappointed with the extra engine capacity as that turbo has a reputations of being a bit tricky with the spool on 1.8T as compressor size is quite big compared to turbine side. Looking forward to your results. Let's hope it will spool early and quick + pull all the way to limiter :evil: :evil:
 

·
Registered
Joined
·
11,542 Posts
nate42 said:
Matt B said:
Nice post Nate - I am looking forward to 2 litre spool :)
You had GT2871R right? I'm sure you won't be disappointed with the extra engine capacity as that turbo has a reputations of being a bit tricky with the spool on 1.8T as compressor size is quite big compared to turbine side. Looking forward to your results. Let's hope it will spool early and quick + pull all the way to limiter :evil: :evil:
Yep, 2871r with the 0.86 AR housing as well. Going 2 litre and large port at the same time with SEM inlet mani - hopefully quick spool and no surging - fingers crossed :)
 

·
Registered
Joined
·
3,425 Posts
TT SMITHY said:
Matt do you know why people generally opt for 82.5 instead of 83-mm on stock crank ?
The reason is that it gives you some room for an extra rebore if it's needed in the future - variety of reasons could cause this as you could imagine

If you have a 83 or 83.5 bore and then go for mega power the bore will wear at an alarming rate, as well as increasing the chance of something letting go. But in this event the block is scrap - if you stick with 82.5mm bore there is a chance of final rebore to 83.5mm

If you went to the max capacity seems the little K04 wouldn't cope :?
 

·
Registered
Joined
·
351 Posts
Hi Smithy

If you need some pistons I have a brand new set of J.E pistons 82.5 for sale let me know if your interested.. Great post by the way u'll love going 2ltr with the right turbo and manifold combination u can make a seriously quick car

Neil
 
1 - 20 of 28 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top