Clio 172/182 diferences between Low & High Pressure Turbo conversions

[Kelman70]

I have been looking into carrying out a turbo conversion shortly on either a 172 or 182.

Now i'm looking for someone to clarify a few points for me in relation to low and high pressure conversion differences

I presume low/high pressure is reffering to boost pressure??

a low pressure turbo conversion can be ran on standard internals from what ive read upto around 230bhp
a high pressure turbo conversion would need uprated rods/pistons.

now the confusion comes with some people choosing to change the compression ratio of the engine by increasing the cylinder head size by fitting a 197 one i believe or changing pistons or machining the original head.

my question is when and why is this modification required? does it require to be done as part of any turbo conversion regardless of if its low or high pressure? or just on a high pressure?

Any help would be appreciated, just trying to understand exactly what is required prior to starting

martin

 

[Chi]

Welcome to CS mate, someone will be along shortly...

 

[Chip-mk1]

You only need to lower the compression ratio if you are running higher boost.

Essentially the reason is to lower exhaust gas temperatures and stop the engine melting.

If you have too much cylinder pressure from excess compression/boost you have to r****d ignition timing to avoid detonation, this in turn makes the burn a lot less efficient and increases heat.

Expect to spend a lot of money to turbo a clio well.

10K is a realistic budget for a good high boost conversion.

 

[SharkyUK]

Any help would be appreciated, just trying to understand exactly what is required prior to starting

A healthy / strong engine and deep pockets (especially if going high-boost)...

On a serious note, welcome to the site mate.

 

[Kelman70]

Thanks for the replies guys.

Just trying to get my head around all the different options before i jump in and get cracking

the plan is to purchase a tastefully modded 172 or 182 to run at track days and have a bit of fun whilst buying another engine and building it as i have time, looking to fit a gt2860r turbo as it seems a good all rounder and wouldne be at its max running 250-300 bhp

ideally id be looking at around the 230-250 bhp mark but build the engine so that it could reach the higher bhp if i decide to, which probably will happen!!

Chip-mk1:- are there specific ratios for different turbos or is replaceing the head with a 197 unit or machining the original sufficient. (i presume it depends how much money you want to spend?)

I'll be starting a thread when my project starts and i'm sure i'll have plenty more questions to ask along the way.

Martin

 

[Chip-mk1]

Might be worth you having a look at some of the build threads on here mate.

For 230-250bhp, personally I would fit a megane gasket to lower the CR slightly, and leave it at that, or even leave it totally standard.

The 197 head does lower CR but only by a very small amount, its a much better option though as the inlet gives you so much space at the front for filter changes etc and you can get to the plugs without seperating it.

CR isnt an exact science so no its not a case of a specific turbo will have a specific CR, it depends a lot on how its mapped (big mid range boost means you need much lower CR than big boost only at high rpm).

also if you have a decent equal length tubular manifold made you will get away with higher CR on the same boost/turbo

a few of us with turbo clios are at bedford on 5th July, you could come along and grab some passenger rides in various specs?


gt2860r is a really really good turbo, but I feel will be a bit wasted on the log type manifolds most people run on these cars, will still work but a tubular would be a lot better.


The thing is though, getting the power is one thing, getting the box to stay in one piece is another.

My engine would happily do 500bhp without too many further mods, but I run it at 300 quite happily knowing at least my box has a fighting chance!

 

[Kelman70]

Might be worth you having a look at some of the build threads on here mate.

For 230-250bhp, personally I would fit a megane gasket to lower the CR slightly, and leave it at that, or even leave it totally standard.

The 197 head does lower CR but only by a very small amount, its a much better option though as the inlet gives you so much space at the front for filter changes etc and you can get to the plugs without seperating it.

CR isnt an exact science so no its not a case of a specific turbo will have a specific CR, it depends a lot on how its mapped (big mid range boost means you need much lower CR than big boost only at high rpm).

also if you have a decent equal length tubular manifold made you will get away with higher CR on the same boost/turbo

a few of us with turbo clios are at bedford on 5th July, you could come along and grab some passenger rides in various specs?


gt2860r is a really really good turbo, but I feel will be a bit wasted on the log type manifolds most people run on these cars, will still work but a tubular would be a lot better.


The thing is though, getting the power is one thing, getting the box to stay in one piece is another.

My engine would happily do 500bhp without too many further mods, but I run it at 300 quite happily knowing at least my box has a fighting chance!

I have had a look at some of the turbo project threads but most seem to be from years ago, running old technology, i understand that the conversion has not changed mechnanically but the mapping etc must have moved on a bit. also there isnt much detials on the cr's etc as most threads have been done by a tuner.

when you say tubular manifold how does this fit in? i presume the turbo is relocated elsewhere to allow the fitment of it?

​martin

 

[Chip-mk1]

Old technology in what way?

tubular manifold will vary where it sits the turbo depending on your requirements.

​Mine is just under 9.5:1 cr and works well.

 

[Chip-mk1]

http://www.cliosport.net/forum/showthread.php?672154-Clio-172-197-forged-turbo-engine-build

 

[Cupman29]

I'm building a similar high boost engine you're after using a gt2860rs and a fuly forged bottom end and some other trick parts. Might give you some ideas.

http://www.cliosport.net/forum/show...d-track-toy!/page19&highlight=172+boosted+cup

 

[Kelman70]

Old technology in what way?

tubular manifold will vary where it sits the turbo depending on your requirements.

​Mine is just under 9.5:1 cr and works well.

Old Tech as in engine control ecu's etc. I should have searched boosted clio and not turbo clio!

martin

 

[Chip-mk1]

TBH there arent many ECU's on the market that are genuinely new tech at the moment. But as you arent going to want to run torque predictive routines etc on a clio turbo anyway realistically, it doesnt really matter.

A good quality ECU from half a dozen years ago like an Autronic Sm4 for example will do everything you are realistically going to need.

Likewise with turbo technology, you dont need the latest borg warner EFR turbo just to do a really mundane 150-200bhp per litre, a traditional plain bearing turbo is pefectly capable of doing that without being excessively laggy anyway.

And through FWD unless you are into drag racing on massive slicks there isnt much point having any more than that.

 

[Kelman70]

TBH there arent many ECU's on the market that are genuinely new tech at the moment. But as you arent going to want to run torque predictive routines etc on a clio turbo anyway realistically, it doesnt really matter.

A good quality ECU from half a dozen years ago like an Autronic Sm4 for example will do everything you are realistically going to need.

Likewise with turbo technology, you dont need the latest borg warner EFR turbo just to do a really mundane 150-200bhp per litre, a traditional plain bearing turbo is pefectly capable of doing that without being excessively laggy anyway.

And through FWD unless you are into drag racing on massive slicks there isnt much point having any more than that.

Had a look at the autronic last night and also the link g4 storm, both seem very good. thats a long way away yet though.

When you speak about tubular manifolds does anyone manufacture these to buy? or is it a custom job?

Martin

 

[len_beach]

The option of a Megane engine and box always gets rejected but why?

Engine and box from an R26 £2.5k say
Customs shafts I can have done for £500
ECU say £1k
A bit of tweaking to get up to 275ish say £1k

So that's £5k total. Why is turboing a Clio engine better?

 

[batesey]

I plan on putting megane rods in and lowering the CR by using an engine dynamics head gasket, Scoff took a standard bottom end with a decomp plate to 450bhp so im pretty confident the standard engine/pistons is strong enough for 260ish reliably with a lower CR?

 

[Chip-mk1]

The option of a Megane engine and box always gets rejected but why?

Engine and box from an R26 £2.5k say
Customs shafts I can have done for £500
ECU say £1k
A bit of tweaking to get up to 275ish say £1k

So that's £5k total. Why is turboing a Clio engine better?

Becuase for decent power the megane engine needs to be pulled apart and rebuilt with forged rods and pistons anyway, the manifold needs to go in the bin, the turbo needs to go in the bin, so you end up with nothing left from it thats actually worth having.
If all you ever wanted was moderate power though (and TBH I would say that more than 300 is of little real use unless you are into drag racing) then it would be ok, but you do realise that to most people the prospect of chopping about the chassis and making their own engine mounts etc is a pretty terrifying one too?

And if you are going to start that sort of fab work, then why not put a proper engine and box in like a Honda engine or a Mitsubishi engine instead of spending 5K plus massive amounts of labour just to fit an engine and box that arent actually very good anyway?

 

[Chip-mk1]

I plan on putting megane rods in and lowering the CR by using an engine dynamics head gasket, Scoff took a standard bottom end with a decomp plate to 450bhp so im pretty confident the standard engine/pistons is strong enough for 260ish reliably with a lower CR?

For 260bhp from a clio engine all you need is a thicker head gasket, nothing else at all internally.

Mine did 10,000 problem free miles like that and that was a right snotty old engine to begin with. (mine used a 197 head and slightly thicker gasket but the same can be achieved with a 172 head and even thicker gasket as MWM have done them that way too)

That was 260bhp/250lbft and drove lovely.