Mike from MWMsport RS2 Phase 1

[Laine_16v]

I feel a little bit more reassured due to the chap on here with the red R26 converted clio 197 running 270bhp with... 333ft lb's! Im sure hes on a stock engine (at least i hope he is).

I think its luck of the draw from the view of cast piston quality variations, and the person who's mapping it.

 

[.Stevo.C.]

It's more the rods that are the weak point with F4rt engine hence why I'm getting forged rods fitted to my megane. Paul at rs tuning says the pistons should run 300+ bhp with the right mapping.

 

[Luke.]

I feel a little bit more reassured due to the chap on here with the red R26 converted clio 197 running 270bhp with... 333ft lb's! Im sure hes on a stock engine (at least i hope he is).

I think its luck of the draw from the view of cast piston quality variations, and the person who's mapping it.

Exactly that.. what sort of power are you aiming for?

Sorry for the thread Hi-Jack

 

[Tutuur]

Why not go for F4RT pistons and rods for the power you have they will handle that pretty well? This was the route I was going to go down originally but plans have changed now..

Also F4RT pistons and rods can be picked up quite cheap now a days

Because chip has a lowered compression by fitting the 197 head, thus no other pistons are needed

 

[batesey]

Are F4RT pistons actually stronger than the F4R ones? just out of interest

 

[Tutuur]

If you look in the table 1 page back you'll see the f4r crown is thicker thus stronger.
However the f4r pistons have really deep valve cutouts making the ringland pretty small at that area.

However thinner crown does transfer heat better so based on theory there isn't a reasonable answer i guess

 

[Luke.]

Because chip has a lowered compression by fitting the 197 head, thus no other pistons are needed

For reliablilty over anything else, whilst the bottom end is being rebuilt, tbh. Meg Pistons and forged rods would be a good and cheapish upgrade..

 

[Luke.]

Are F4RT pistons actually stronger than the F4R ones? just out of interest

Rods are the same IIRC, pistons are stronger..

 

[Chip-mk1]

Rods are the same IIRC, pistons are stronger..

Stronger in what way?

Afaik they are both just exactly the same construction piss poor cast rubbish.

 

[Luke.]

They can take more then 250bhp, they can't be that bad if they can run a megane at stage 2 reliably..

 

[DannyR]

Rods are the weak link, they're different between the two.

 

[Tutuur]

Rods are the same afaik.

And Luke, you aren't reading. Chip has lowered cr due to the 197 head. If he fits Meggie pistons the cr will be silly low.
as i said before f4r are beefier anyway so propably 'could' be stronger

 

[neil a]

Im hoping to fit my 197 cams in a few weeks , hopefully to Mikes timing settings will be intresting to see how they work on a ITB car.

 

[Luke.]

Rods are the same afaik.

And Luke, you aren't reading. Chip has lowered cr due to the 197 head. If he fits Meggie pistons the cr will be silly low.
as i said before f4r are beefier anyway so propably 'could' be stronger

I did see that bit. Thought F4R internals were like chocolate??

 

[Tutuur]

Maybe you're confusing it with gearboxes?
They are often called chocolate

Pic's off the 3 F pistons:

As Chip mentioned the casting on F4 pistons are far worse then F7 casting.
That's why i'm going with skimmed f7's for my turbo'ed F7r

 

[Luke.]

No, I just didn't think they could take more then about 240/250bhp..

Glad I've gone for forged now.

What sort of power are you aiming for?? Sounds interesting.

 

[Chip-mk1]

Luke. The f4r pistons aren't weaker than f4rt, the thing that limits their power by comparison is just the cr. lower the cr and they are just as capable.
Mine made 260bhp for 7k miles. Since then I've increased the boost significantly and it's still been fine for the last thousand or so miles and a couple of trackdays. I've two more trackdays this weekend as well.

Only issue mine has is breathing heavy, but that's cause the rings were worn out when it was n/a and mwm and me just wanted to see how far we could push a tired old n/a bottom end.

 

[Tutuur]

How muc boost are you running Chip? And what c/r is it now?

 

[Laine_16v]

My 225 pistons don't have a coated skirt like the one in your picture Tutuur

As above a skimmed F4R piston should technically be able to produce the same power as a F4RT piston providing the same compression ratio and the reduced crown height hasnt affected the strentgh of the piston.

 

[Chip-mk1]

How muc boost are you running Chip? And what c/r is it now?

Its just under 9, and running 20psi peak holding 12 and then tailing off to 10 at the top end (turbo cant flow enough to hold more)


I would strongly advise against large skimming pistons as a method of lowering CR, it will invariably weaken them.

 

[Tutuur]

i know, it's just a try and learn project anyways.

currently driving 10psi on 1mm skimmed w/o squish band skimmed, now going to skimm the squish band aswell so i'll end up around 9:1. piston crown is only .2mm thinner then f4rt pistons afster skimmage.
i'll give it a try

 

[Luke.]

Luke. The f4r pistons aren't weaker than f4rt, the thing that limits their power by comparison is just the cr. lower the cr and they are just as capable.
Mine made 260bhp for 7k miles. Since then I've increased the boost significantly and it's still been fine for the last thousand or so miles and a couple of trackdays. I've two more trackdays this weekend as well.

Only issue mine has is breathing heavy, but that's cause the rings were worn out when it was n/a and mwm and me just wanted to see how far we could push a tired old n/a bottom end.

I stand corrected.. I was going to go down the route of meg internals but decided against that shortly after..

What head gasket are you running? I didn't realise the 197 head changed the CR that much..

 

[Coops Mk1]

how come the peak to held boost is so big? 20 down to 12 seems mad to me, or is it mapped to do that?

 

[Chip-mk1]

I stand corrected.. I was going to go down the route of meg internals but decided against that shortly after..

What head gasket are you running? I didn't realise the 197 head changed the CR that much..

Its on a f4rt head gasket.

 

[Chip-mk1]

how come the peak to held boost is so big? 20 down to 12 seems mad to me, or is it mapped to do that?

Its drives nicely like that, the boost peaks to 20/21psi but then rapidly drops to 12 and holds there, gives you a nice initial punch as you floor it but not so much so that it spins the wheels or anything like that, its actually mapped so that its deliberately a little lazy at 20/21psi so that it doesnt make too much torque briefly while seeing that boost, but it means that the turbo spools quite quickly and then as the revs increase its already pulling hard.

 

[Coops Mk1]

is that achieved with a variable boost controller then?

 

[Gray]

The F4RT and F4R use the same rods.

Different pistons, but they are the same materials / construction method.

The rods are the limiting factor... They bend with too much torque or the rod bolts have let go (from what I have seen).

My r26 has been running 302bhp / 312ft.lb on a standard bottom end, with ARP rod bolts for the last 20k with no issues at all.

 

[Chip-mk1]

is that achieved with a variable boost controller then?

No I have done it mechanically, by using a manual boost controller to set the held figure and using pipe lengths to tune the overboost.

At some point I will put it on an electronic solenoid, just havent got round to it yet, and TBH not much point while I have the current turbo and internals, as I wouldnt want it any different to this at the moment anyway, but if I go forged and a bigger turbo later on it would be useful then.

 

[Dan@SJM]

I think i have a spare N75 lying around here if you want to use that chip.

 

[Chip-mk1]

As I said mate, no point me changing it for now, its pretty much perfect for what I want currently, thanks for the offer though mate.

 

[Laine_16v]

Gray lovely output that! exactly what im after.

 

[Dan@SJM]

I just meant as on when you wanted to use it. I doubt I'll be using an N75 for the control of the holset.

 

[Chip-mk1]

Ok mate, thanks, perhaps we could swap it for that combe session you are having off me

 

[Dan@SJM]

sounds like a plan mate.

 

[.Stevo.C.]

The F4RT and F4R use the same rods.

Different pistons, but they are the same materials / construction method.

The rods are the limiting factor... They bend with too much torque or the rod bolts have let go (from what I have seen).

My r26 has been running 302bhp / 312ft.lb on a standard bottom end, with ARP rod bolts for the last 20k with no issues at all.

Hydrid turbo gray? And is that with a decat?

 

[Gray]

Hydrid turbo gray? And is that with a decat?

Yes and yes

Hybrid turbo
Turbo back 2.75" exhaust
630cc Siemens Deka injectors
forge intercooler
forge actuator
forge re-circ valve
forge boost pipes / hoses
ARP rod bolts

It goes really, really well... Mid range pull is brilliant and it puts the power down so easily.

I would love more, but the next step would be a forged engine.

 

[.Stevo.C.]

Yes and yes

Hybrid turbo
Turbo back 2.75" exhaust
630cc Siemens Deka injectors
forge intercooler
forge actuator
forge re-circ valve
forge boost pipes / hoses
ARP rod bolts

It goes really, really well... Mid range pull is brilliant and it puts the power down so easily.

I would love more, but the next step would be a forged engine.

Only thing I'm missing from that list is the turbo, decat, uprated injectors & rod bolts lol.

I'm booked in at rs tuning to have Manley rods & arp bolts fitted in October then I'll probs go down the Siemens injectors with an Itg kit and another map. How loud is your exhaust with the decat?. My cup is running 270 bhp & 285 lbft and puts the power down really well too but I'm always craving more power. I think I would be happy with 300/300 perfect figures for the road.

 

[Gray]

Only thing I'm missing from that list is the turbo, decat, uprated injectors & rod bolts lol.

I'm booked in at rs tuning to have Manley rods & arp bolts fitted in October then I'll probs go down the Siemens injectors with an Itg kit and another map. How loud is your exhaust with the decat?. My cup is running 270 bhp & 285 lbft and puts the power down really well too but I'm always craving more power. I think I would be happy with 300/300 perfect figures for the road.

How come you are having rods fitted, but not pistons / bottom end build?

I don't think the standard pistons will go much more than 320bhp~?!

You'll need larger cc injectors and a revised intake for anything over 285bhp..

Sorry for the thread hijack, OP

 

[.Stevo.C.]

How come you are having rods fitted, but not pistons / bottom end build?

I don't think the standard pistons will go much more than 320bhp~?!

You'll need larger cc injectors and a
revised intake for anything over 285bhp..

Sorry for the thread hijack, OP

Because I can't justify the 4k+ price for a fully forged engine and I won't be going anywhere over 300 bhp so the rods and bolts will do me fine especially at the price paul is doing them for.

Yeah seen on meganesport that the standard injectors are on there limit on stage 2 so uprated injectors and an Itg induction kit are on the cards.

 

[Chip-mk1]

Because I can't justify the 4k+ price for a fully forged engine and I won't be going anywhere over 300 bhp so the rods and bolts will do me fine especially at the price paul is doing them for.

Yeah seen on meganesport that the standard injectors are on there limit on stage 2 so uprated injectors and an Itg induction kit are on the cards.

Just to drop in some forged standard sized pistons and new rings on a honed set of bores would probably only add 500 quid to the bill.