I didn't investigate Andy, so it is just 2p's worth, barelyTake it with a pinch of salt.
I was being a cheap skate, using standard pistons and rods at 2 bar of boost. I got a few weeks out of them until one came though the front of the block, the other 3 were bent and probably not far behind.
My plan is the cheap skate one without the piston / block inference problem. Slightly less pressure than you thoughOriginally Posted by Scoff
I didn't investigate Andy, so it is just 2p's worth, barely
I was being a cheap skate, using standard pistons and rods at 2 bar of boost. I got a few weeks out of them until one came though the front of the block, the other 3 were bent and probably not far behind.
What I am ultimately looking for is what enables the meg250 to run more torque and not kill the rods ?
Yes, I wasn't happy about that interface problem, it happened during some late night motorway mapping the night before a big santa pod meeting.
I don't know about the Megane 250 differences sorry. Seems to me that if they're the same rod then they should have much the same limit. Small changes in compression ratio are not going to bother them much.
From what I am discovering the head is worked differently and has more volume. The pistons are different ( same rods ) and VVT.
It drops the CR quite drastically.
Looking into my options
The cylinder head seems to be the same as the 197 clio, with the VVT and cam sensor fitted, but I've never seen the combustion chambers to see if they are the same as the clio or the same as the old 225.
I'm guessing the pistons will have valve cut outs due to the VVT and wilder cams, theres a 250 running a gtx 28 turbo and it's making pretty much the same as I was at 1.2 bar. So I'm guessing the cams aren't a million miles away from a stock set off 182 cams.
If the rods are the same then compression height must be the same, so we can't blame rod ratio. If compression is much lower then maybe that's a factor but I can't see Renault dropping the CR more than a couple of 10ths ?
Does the 250 have the same CNC cut inlets as the 197 Steve ?
Not sure Chris, I'm in the same boat as you and not really had loads to do with them. I'm sure the inlet manifolds were the same though.
Heres a thread on meganesport, theres a photo without the inlet on and they look the same shape as a standard 225
http://www.meganesport.net/community...n-Megane-RS-II
Looks like the 250 is running fuel return, you can see the FPR in the centre of the fuel rail
There might be something in how well the ECU deals with transients, sprung mass flywheels doing weird stuff, traction control putting in crazy torsionals. Or maybe it is just the cylinder pressure (torque) bending them. Either way, they don't look especially stout, not like the midget wrestlers forearms in the GTT.
Ah I see Steve. The 197 has very large inlet ports, 60x32mm with some nice CNC work. bare cast exhaust ports, the same as a 182.
that makes a lot of sense, even my Twingo is like that
Yeah, whilst the 225 heads have that small cut out at the top of the port for the injector angle. They do look big ports on those photos so it could possibly be that they have modified the 197 head?
I know, but believe it or not meg 225's and 230's have the FPR in the tank, with no boost reference. People fit 630cc injectors to compensate for the fuel leaning out when the boost is turned up.that makes a lot of sense, even my Twingo is like that
If I had a meg 230 it'd be fitting a 250 fuel rail and a fuel return.
I remember telling someone to try F7 rods Andy. They're a beefy item and 144mm, so they go right in. He retorted with "I've been told they're made from poor material and I was advised against it". So who knows. That could be good old tuner bull****. What I do know is that I've never seen an F7 rod break. Plenty of them are turbocharged running healthy power. But, thats another 2p, so remember to apply the salt
Those are smaller than 197, but look wider than the 225 so maybe it's a 197 style casting with a different port. The 197 inlet port is a bit serious for a factory turbo.
Yeah that's part of the reason I used a 197 head, in hind sight if I'd of known it would take so long I'd of had the exhaust ports modified.
It's more likely that the F4 part has had a lot more structural analysis to take weight out of it, that may mean that it's a better material, but it might not mean that it's stronger. more lieky they found that they didn't need to be as strong as the F7, so cheapened them. I'd want to do some testing before taking any of this as gospel. They'll be fine in my car, and if not I'll have to build a monster to get the benefit of the stronger partsI remember telling someone to try F7 rods Andy. They're a beefy item and 144mm, so they go right in. He retorted with "I've been told they're made from poor material and I was advised against it". So who knows. That could be good old tuner bull****. What I do know is that I've never seen an F7 rod break. Plenty of them are turbocharged running healthy power. Thats another 2p, so remember to apply the salt
8.7:1 down to 8.4.1
Meg 230 head is 42.4cc , 250 45cc
The 250 doesnt have a return , but does have rising rate. .that makes a lot of sense, even my Twingo is like that
I measured a 197 head at about 45cc I recall, so possibly the 250 and 197 chambers are the same. 8.4:1, thats a low CR for a modern turbo engine!
You recall correctly !
the 172/182 has the same cc as the 225/r26
It looks like an FPR on one of those photos, you sure they don't have a return? if not I wonder if its a fuel rail off something else?
I know the VW 1.8T fuel rail has exactly the same injector spacings as an F4R, it just needs the securing tabs modifying
I just had a squint around the internet, Paul from RS tuning describes a 5 bar regulator in the tank, and a 3 bar on the rail, but with no return. I guess that means the one in the rail is more like the regulator on a gas bottle rather than the pressure release valve we're used to.
There must be a reason for the 5 bar regulator, I suspect the one in the rail requires it to remain stable, so it possibly won't work alone. That, or maybe it's to stop the pump running at it's own full pressure continually, driving hard against the rail regulator (full pressure is max current, so a hard environment for the pump to live, and a waste of power).
Assuming Paul is correct about those pressures, line pressure will limit at under 2 bar boost, not a problem for most. There is nothing to say that the regulator will be able to flow enough for an engine with 2 bar boost, so it may well drop off before that.
For an easy life I'd stay away from this setup until someone has tested it at the kind of power you'd want to run (unless you have the bits sat there, in which case I'd bench test their limits before going anywhere near a car).
I have never had this prob with the T2 or gtt....
I did ask around an email various company's and they said it might of been the discs!
I've still got there here as when the killed the set of discs that was on the car... I bought pads and hc discs from Brembo and just fitted them as a set
tbh I might throw them back in soon as a few of us are planning a weekend of 'playing' and see what they are like with the brembo hc discs but if it stops any quicker than what it does at the moment... my mates 330ci might join forces with my rear bumper as he couldn't stop as quick as me last time we 'played'!!
Maybe I'm just having a brain fart, but that sounds ridiculous?
Surely if it has a a 5 bar reg in tank, then the whole fuel system including the rail will be at a constant 5 bar fuel pressure?
I'm guessing that the ECU must use the MAP sensor to calculate any fluctuations in the fuel pressure to keep the fueling correct.
I know of a meg 250 in France running 380bhp with a hybrid turbo but that one's forged.
I asked the lad if he had pictures of the original pistons and rods but he never replied unfortunately!
I'm very curious myself too even if it's only for the knowledge.
Regarding the f7 vs f4 rods, yes they are way more beefy!
Btw, Andy how is your project doing? You never made a thread on here right? And the one on cs isn't updated for quite a while...
If the regulator is on the inlet to the fuel rail, the fuel rail will be at 3 bar, and everything else will be 5 bar. This assumes that it's a regulator, not the prv that we're used to.
it's stalled, I'll update here when there is more news. In short, getting the gearbox sorted has been a saga, but I have it back now. I'm working outside, and it rains on every free day I get
Is there any possibility that the pads are fake? On the GTT I had cheapo disks, wear wasn't an issue, it only ran for a minute at a timeI have never had this prob with the T2 or gtt....
I did ask around an email various company's and they said it might of been the discs!
I've still got there here as when the killed the set of discs that was on the car... I bought pads and hc discs from Brembo and just fitted them as a set
tbh I might throw them back in soon as a few of us are planning a weekend of 'playing' and see what they are like with the brembo hc discs but if it stops any quicker than what it does at the moment... my mates 330ci might join forces with my rear bumper as he couldn't stop as quick as me last time we 'played'!!
Lol, so many guys called Andy i must have made a mistake.
I meant speedy
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Surely if the line pressure is 5 bar, the rail reg doesn't have anywhere to vent the excess fuel pressure due to not having a return line so it will also hit 5 bar?
Tutuur, it's coming along slow mate. I'm hoping to have it finished by the summer but it's all work dependant. Heres a small pic of what I'm working with
Think about a gas bottle regulator, where does that vent to?
A normal fuel pressure 'regulator' is a PRV, not a regulator.
I see what your saying Andy, I still think its a stupid set up though.
Hhhmmm twinscroll? Gt35?
Exactly my kind of stuff! This is what i want to build in the future!
it does seem an awfully complicated way not to have a return line. But then we're not trying to save pence off the price of building a car.I see what your saying Andy, I still think its a stupid set up though.
It's just a GTX3071R
Obviously a GTX35 will bolt straight on so it's future proof
If i read all the Amreican forums good they say the response of a ts gtx35 is the same as a gtx3071 ss.
The 30 will probably be just as or maybe more responsive than the 2871 because of the t2 iwg housing.
Will be good to see how yours goes as i'm destined to build a ts big turbo f4 in the future!
Ideally I'm trying to replicate the GT28RS response with a stronger top end than the GT2871R, from what I've read regarding twin scroll setup's is they don't look any better on a dyno graph but they give much better road manners and response.
We'll see what its like when I get it finished.
Well i've seen a few evo dyno's and they did spool a bit better than their ss counterparts but as you say the transient is supposed to be out of this world!
Steeve, how are the supply runners to the wastegates fitted? Are they fron a divided collector or branched from a pair of runners? Are the supply runners equal length to each gate? Ive really had to compromise on mine and have one longer than the other. Not sure what real world impact that might have on the control?Tutuur, it's coming along slow mate. I'm hoping to have it finiscollector I'mummer but it's all work dependant. Heres a small pic of what I'm working with
Scoff can some sort of trick boost controller sort any indifference in the wastegate controls?
Now then chubby cheeks I'll what's app you a picture of my manifold.
i wish... bought from tweeks at £130!!Is there any possibility that the pads are fake? On the GTT I had cheapo disks, wear wasn't an issue, it only ran for a minute at a timefrom when I spoke to the guy at the brembo importers he said that from the info he had, the std discs aren't brembo items, and I should use them with HC discs, which I now have... tbh I'll give them ago again soon, but it means swapping them... and its cold and wet and as the car stops at the mo, I' can't be arsed! LOL
Open a project on here mate! I want to see them too
Paul has just made 352bhp on a Meg 250 running stock internals looks to be about 370lb/ft of torque as well.
Upgrades are hybrid turbo, 630cc injectors and a 3" turbo back exhaust.
Not a bad effort
No banana'd rods at that level of torque then?
Re: Engine Dynamics F4R Turbo Conversion
Wow. Did the gearbox last the whole power run?
250 engine with different pistons than that r26 engine. Sarcastic so and soNo banana'd rods at that level of torque then?
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