Jump to content

Welcome to the brand new 205GTIDrivers.com website! We hope you'll enjoy it! Read the full notice here.

Sign in to follow this  
Andy M1tchell

Is It Possible To Run An Mi16 Oe Bottom End With An 8v Head

Recommended Posts

Andy M1tchell

Hi

 

As a bottom end performance upgrade for my 205 8v turbo is it possible to run an oe mi16 bottom end with the 8v head from my 8v turbo engine.

Reason being that the mi16 bottom end can withstand higher rpm, has thicker liners, and a stronger crank. I know that both bottom ends are vertually the same although the mi16 pistons have cut outs for 4 valves where as the 8valve pistons have cut outs for 2 valves. So swap the mi16 pistons for 8valve forged pistons.

I thought this could be a lot less hassle free than rebuilding an 8v bottom end to a higher spec! also i have seen a recently rebuilt mi16 bottom end for a decent price

Share this post


Link to post
Share on other sites
bensonmi
Hi

 

As a bottom end performance upgrade for my 205 8v turbo is it possible to run an oe mi16 bottom end with the 8v head from my 8v turbo engine.

Reason being that the mi16 bottom end can withstand higher rpm, has thicker liners, and a stronger crank. I know that both bottom ends are vertually the same although the mi16 pistons have cut outs for 4 valves where as the 8valve pistons have cut outs for 2 valves. So swap the mi16 pistons for 8valve forged pistons.

I thought this could be a lot less hassle free than rebuilding an 8v bottom end to a higher spec! also i have seen a recently rebuilt mi16 bottom end for a decent price

 

dont know from experience but just been reading on the rally forum about a 8v using mi bottom end,wast turbo tho,he used diesal bearings for strength and it reved to 8500 rpm reliably he said.

Share this post


Link to post
Share on other sites
Andy M1tchell
dont know from experience but just been reading on the rally forum about a 8v using mi bottom end,wast turbo tho,he used diesal bearings for strength and it reved to 8500 rpm reliably he said.

 

 

 

Hi ok thanx for your help I think it is possible just never heard of it done before have you? I am sure both 8v and mi16 bottom ends are the same except for the different crank, thicker liners and the pistons I thought why bother rebuilding an 8v bottom end using mi16 components I may as well use an mi16 bottom end and just change the pistons for 8valve forged items

Edited by Andy M1tchell

Share this post


Link to post
Share on other sites
bensonmi
Hi ok thanx for your help I think it is possible just never heard of it done before have you? I am sure both 8v and mi16 bottom ends are the same except for the different crank, thicker liners and the pistons I thought why bother rebuilding an 8v bottom end using mi16 components I may as well use an mi16 bottom end and just change the pistons for 8valve forged items

 

i wanted to do it before but mi head on turbo block,think thats been done before

Share this post


Link to post
Share on other sites
welshpug

you'll need 8v rods too, they're wider than the Mi ones and fit onto the gudgeon pin differently.

 

codswallop about diesel bearings being stronger, they're the same material, BUT available in thicker sizes to allow for a heavier crank grind.

 

 

is your 8v turbo engine a TT one or an iron block 2.0, or a hybrid like Henry yorke's?

Share this post


Link to post
Share on other sites
Andy M1tchell
you'll need 8v rods too, they're wider than the Mi ones and fit onto the gudgeon pin differently.

 

codswallop about diesel bearings being stronger, they're the same material, BUT available in thicker sizes to allow for a heavier crank grind.

 

 

is your 8v turbo engine a TT one or an iron block 2.0, or a hybrid like Henry yorke's?

 

 

 

Hi thanks agin for your kind help - no its not a 2 litre cast block it is the 1905 aluminium block. Has henry yourke still got that 205 cti built by darren at spoox? I have been outta this scene for the past 4yrs since i gave up on my last 205 turbo and bought a boring diesel van for work

Share this post


Link to post
Share on other sites
Miles

You need as you;ve said some low compression pistons the 16v ones are far too high,

Again a common mith is the 16v liner's being stronger, They have extra rib's for cooling mainly, the thinest part of the liner is between them and 8 & 16v are both the same here and are the weakest point on both.

As WP has said the bearing's are either Alloy or Lead/cooper based, the lead/cooper ones cannot be made in europe AFAIK but can be imported from down under which I do, you'll see lot's of companies say Group N or Competition bearing's which 99% of the time are just std items.

 

But you can use either 8v or 16v blocks and cranks, liner's etc in any combo, just the rod's and pistions you need to check and minor mod's on the blocks to fit the engine mount's and cam belt tensioner's

 

Henry's car has been fixed since it's trip to Spox as there was quite a long list of problems with it.

Share this post


Link to post
Share on other sites
Andy M1tchell

Henry's car has been fixed since it's trip to Spox as there was quite a long list of problems with it.

 

 

Yeh i remeber hearing all about it many years ago at the time about the same time as i had my 205 tt built by 205 parts. I remember henry putting that picture of a skip over the picture of his car loved every minute of it because I had fell out with darren but time has moved on

Share this post


Link to post
Share on other sites
tony perks

Think that was my post on the rally forum, and the TD bearings we use are Lead indium bearings which are a more durable material than the standard XU ones which are now only Steel alloy, the reason we use TD bearings is on the mains that feed the big ends you use a bearing with the groove on the top and bottom, which gives constant oil feed to the big ends, which with a plain bearing fitten to the block the ends only get supplied every half revolution, some say this is sufficient but personally I'd rather not take a chance. As for using grooved bearings all roung some people also say a plain bearing has better load bearing capability( same as for the MG Metro turbo Blocks), but as thay are only used on the 2 journals, we have had no Failiures yet on any engine we have built using this combination using up to 8500rpm.

 

And as Miles has said the bearings we use are from Austrailia, and they also do a range of proper race type bearings with out the soft lead shiney flashing, I have used these on EVO and EJ20 engines but they need carefull running in and are very critiacal in the bearing/ journal clearances.

Share this post


Link to post
Share on other sites
Sign in to follow this  

×