Forged Pistons turbo

Level 2 User Joined: 22 Jan 2006 Posts: 55

I'm carrying out a turbo conversion using a T25 turbo as im only looking for gains of around 180-200bhp. I am aware however that i could probably run this sort of power on standard internals however to future proof it im looking to low compression the engine.

My question is, which size pistons do i need? The engine block is completely standard and no modifications have been made to the crank or bores. Its running on standard size bearings also. k-tec and wossner offer 3 different sizes, which ones do i need? Idealy i wanna run pistons of comp ratio 9.0:1 as i was told once that 7.5:0 would be pointless with the set up im going for. the piston sizes are as follow:

K-tec: 82.7mm, 83mm, 83.5mm

Wossner: 82mm, 82.5, 83mm at a comp ratio of 8.0:1

Which ones would fit a standard bore?

cheers

Forum Moderator Joined: 18 Feb 2004 Posts: 7432

82.0mm is standard bore for the F7P. Not that big a deal to have it bored out slightly bigger for any of the others though. Will give you a nice new surface for the new rings too.

Retroholic Joined: 23 Dec 2005 Posts: 3315

8.5:1

http://www.iapel.com/main_en_productos_renault.asp

speak to them Thumbs Up!

also slight rebore will be worth while as it will be the best snug fit

Level 2 User Joined: 22 Jan 2006 Posts: 55

Thanks for the links but the amercians are selling pistons are silly prices. U've jus gota give them the specs u want.

http://search.stores.ebay.com/9-0-1-pistons_W0QQcatrefZC6QQfromZR10QQfsooZ1QQfsopZ1QQftrtZ1QQftrvZ1QQsacatZQ2d1QQsaprchiZQQsaprcloZQQsatitleZ9Q2e0Q3a1Q20pistonsQQsbrexpZWD1SQQsifZ1QQsofpZ4QQssPageNameZWD1S

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

why go lowe comp? best way to ruin a good engine I suppose

Level 2 User Joined: 22 Jan 2006 Posts: 55

For gains of 180-200bhp u think i should leave the standard internals then?

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

standard CR less than 5 psi boost, great response and economy

or drop the CR, boost 10 + psi, poor economy, response and no low speed torque

Level 2 User Joined: 22 Jan 2006 Posts: 55

I like the sound of the first option of 5psi boost, as long as it gets me 180-190bhp and saves me having to rip out the old pistons and new rings, headbolts, gasket kit upper and lower, i had fitted a few weeks ago.

This is prob a silly Qn but where is the boost pressure adjusted from? i have nooooooo idea. I knew nothing bout these cars before i started using this site im still learning so bare with me.

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

boosts adjusted at the wastegate.

Boost pressure can be measured at the compressor outlet, induction pipework or the best place which is the inlet manifold.

10 PSI at the tubrbop may only be 5PSi at the inlet manifold due to pressure drops

Level 2 User Joined: 22 Jan 2006 Posts: 55

Ok thanks for the advice. I'll ask nearer the time once ive got all my bits ready for more advice. just waiting for the fastchip ECU and map sensor to arrive. still need to tby the turbo exhaust manifold and downpipe.

Retroholic Joined: 12 Feb 2004 Posts: 5685

5psi on standard CR makes for a very nice car providing you've decent intercooling

Level 2 User Joined: 22 Jan 2006 Posts: 55

Chet ur purple turbo is wat made me decide to convert my car once i watched ur video, but that thing looks like its running some high boost and the sound of that turbo was awsome.

I've got a lil problem, ive changed all the discs, pads, orignial suspension all round, wishbones, track rod ends, bushes and top mounts to standard spec. They've only been in there for a week would i need to change anything again to run a low boost conversion?

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

Level 2 User Joined: 22 Jan 2006 Posts: 55

Faaaaaaaaaaaaaaaaaaaaaaaaaaantasic!

hey, you think its worth buying this oil cooler?

http://cgi.ebay.co.uk/13-ROW-OIL-COOLER-KIT-5-18-19-21-GT-TURBO-CLIO-16V-172_W0QQitemZ150034947394QQihZ005QQcategoryZ10410QQrdZ1QQcmdZViewItem