Tuning turbo time!

[Karolis]

One guy here in Italy said me that saw 1.2 16v rods and 1.4 tjet rods, same dimensions, only 2mm more around piston pin. Should be strong.

The 8v rods are even more stronger?

I also checked on fmecat.eu , the crankshaft bearings are the same between all the 1.2 1.4 n/a and tjet, but this doesn't means that crank is the same...

 

[craigb244]

One guy here in Italy said me that saw 1.2 16v rods and 1.4 tjet rods, same dimensions, only 2mm more around piston pin. Should be strong.

The 8v rods are even more stronger?

I also checked on fmecat.eu , the crankshaft bearings are the same between all the 1.2 1.4 n/a and tjet, but this doesn't means that crank is the same...

maybe he compared them to the mk1 rods?
There is a photo of the 8v rods (cast iron) huge things. a mk1 16v rod (which is the newer stronger/lighter powdered metal rods) but for some reason the small end is VERY thin. also the big end it cut rather the cracked like the newer rods are (which makes the big ends really accurate and a lot stronger)


the cranks are all the same from every fire engine (as in bearing sizes and such.... ) as far as i know. but the throw of the crank is different (thats what has increased the capacity mostly from the old 900cc fire engine all the way to the 1.4)

the difference between the 1.4 n/a and the 1.4 t-jet .... according the fiats documents is the t-jet has a forged crank.

anyway I did worry after munkul threw a rod but there could be a lot of reasons for that and I dont think everyone should worry from one persons issue.

munkul had a lot of problems with the rods.

the pistons had a pin that was to large and as such he needed to get the small end machined out. and according to munkul the guy who did them was not every clever.

with that type of rod they only need a surface fracture to cause an issue (the machinist posted them back loose in a box!) also if he machined them without any support on the small end (most would just bolt it flat down on with the bid end) then the machine would put a side load on the rod... something it was NEVER designed to see

 

[Karolis]

Oh yes, I was only making my "mind jobs of theory", I'm not worried about munkul engine explosion.

I just would like to understand what is the better "mix" of parts (like with the Lego games that I grow up with, take three separate kits, mix them and build your own taking better parts from each one ). Now I really can't understand what changes were made to the Fire engines during time, rods pistons head gaskets etc.

I really don't know what comparison was made, because I didn't even saw the pics or numbers.

So, Mk1 and Mk2 rods are different?

About what photo are you talking?

I can't understand which are new ones and old ones from your words...

http://www.autohenter.dk/fiatdir/Tricker/Billede 232.jpg
At left, 16v rods, at the right 8v rod. Right?

https://www.fiatforum.com/attachment.php?attachmentid=59210&d=1236261626
Left 8v, right 16v.

At the first pages you said that the 16v rods are much better, now we're talking about 8v rods are better, or there's something that I don't understand? (sorry, my imperfect english sometimes doesn't helps me with understading and explaining well)

Found also these photos: https://www.fiatforum.com/cinquecento-seicento/180108-turbo-time-40.html?p=2691581

 

[fingers99]

Shorter rods also loose the squish and lead to higher con rod angle which means more force on the rods and higher side loading on the pistons and cylinders.

True -- unless you take up the height with a bigger piston ring land. The side loading shouldn't be a major consideration on an obscenely long stroke engine like the SuperFIRE -- we're only talking of shortening the rods 4mm or so. And by making the piston taller -- and hence re-creating the squish -- we are actually increasing the thrust area.

And I can say that the T-jet uses the same rods as the 1.2/1.4 16v n/a engines

I'm sure FIAT give the material for the 1.2 16v as nodular cast iron, not sintered, in the Panda manual.

But Munkul's unfortunate experience -- and the dialogue with Peter is still on Performance FIAT -- was predicted.

 

[Munkul]

I really dont think it was down to the strength of the conrod. If it was going to fail anywhere due to material/design, it would have cracked further up nearer the little end, which never looked all that strong.

I wish I had been able to strip it down and hopefully gain some more knowlege of the failure, but from what I could see, it had broke right in the middle of the rod. Its just speculation, but I think its more likely that this was a one-off failure. I could be wrong, of course.

The mk2 16v rods are really nicely finished in comparison to the 8v ones, and they have a much more pronounced I section. From Craig's comparison photo I think, given identical materials, I'd still go for the 16v ones!

Of course this is just opinion, only way to really scientifically determine this is to do lengthy and possibly expensive tests...

I think this squish business is WELL overrated. Unless you leave edges of the crown high, and simply dish the centre of the piston out (possibly weakening it too much?) you will never get the squish as well as fiat did from the factory... and FFS its turbo'd, you dont need to worry about fuel efficiency, and as for VE, its MUCH more effective to port the head than to **** about with this squish ********!
Don't figures tell you anything? Decomp plates are widely used in a variety of turbo conversions on different engines throughout the world; they are simple, effective, and are capable of holding decent power. WHEN done properly. Nuff said.

 

[woj]

I think this squish business is WELL overrated. Unless you leave edges of the crown high, and simply dish the centre of the piston out (possibly weakening it too much?) you will never get the squish as well as fiat did from the factory... and FFS its turbo'd, you dont need to worry about fuel efficiency, and as for VE, its MUCH more effective to port the head than to **** about with this squish ********!
Don't figures tell you anything? Decomp plates are widely used in a variety of turbo conversions on different engines throughout the world; they are simple, effective, and are capable of holding decent power. WHEN done properly. Nuff said.

I sign under There is one more strong argument - when going the piston way in practice you get a fixed CR for the rest of the life of your engine, when you go decomp plate way you are free to change it once you realise you have too much or too little (not to mention that you can always revert back to n/a if needed, but who would do that )

 

[craigb244]

I think this squish business is WELL overrated. Unless you leave edges of the crown high, and simply dish the centre of the piston out (possibly weakening it too much?) you will never get the squish as well as fiat did from the factory... and FFS its turbo'd, you dont need to worry about fuel efficiency, and as for VE, its MUCH more effective to port the head than to **** about with this squish ********!
Don't figures tell you anything? Decomp plates are widely used in a variety of turbo conversions on different engines throughout the world; they are simple, effective, and are capable of holding decent power. WHEN done properly. Nuff said.

it might be over rated but I did read a lot of in at college and it all made sense to me

the squish on my pistons are exactly as fiat made them.

when I said efficiency I meant combustion efficiency... I couldnt care less about fuel efficiency... its never going to be good lol

The main effect I wanted from the squish is the way it shields the rings from the combustion chamber. practically removing(greatly lowering) the chance of overheating the piston rings or blowing ring lands

this reduces the need for fingers idea of lowering the ring pack which in turn needs shorter rods.... both something that DO have negative effects on other areas.

its all about finding a compromise

But yes I agree about decompression plates being fine (I actually have one ready to use if needed)

 

[fingers99]

Compromise? Hah!

As I see it decompression plates are an effective, cost saving bodge. But they do work pretty well.

I'm still worried by the idea of welding up a piston and then machining it. At best it leaves you with ring lands which are the same size as the factory used for the n/a engine which are less than optimum for a charged one. Remember, the ring lands are crucial for dumping heat out of the piston. At worse, it leaves you with a piston with two or 3 distinct metalurgies, and you may loose much of the tempering in the piston: in places it may be annealed. Try cutting or bending any given aluminium alloy in T6 and T0 states and see the difference!

[Aside] Back in the day, Dave Walker used to buy in forged pistons with the tops unmachined, so he could re-work them to his specs. This looks to be what GC will be doing to Brooky's engine, although he'll send the piston manufacturers his specs. (Dunno what the progress is on that engine.) There's no reason, if your machining skills are up to it, why you shouldn't buy blank, unmachined forgings and do the lot yourself. Way outside my talents, though.[/Aside]

Both ways are superior to simply machining the top of the piston off flat.

In all engines, the rod length (with the bore/stroke ratio taken into account) is important, but important only within certain limits. Consider that the 1242 is essentially a stroked 1108, the 1368 a bored and stroked 1242............

Bell actually cites advantages of a shorter rod in forced induction engines...........

But, to my mind, the most economic compromise is simply to buy a T Jet and bolt it in. That allows some brain space to sort out the torque steer, the anti-lift front end and the traction control...........

 

[craigb244]

the most economic route would be just buy a set of t-jet pistons. there is not much of a t-jet that would fit. by the time you have it so it fits in the cento it may aswell be a normal 1.4 with t-jet pistons.

anyway I don't think our centos will take much more power then I've got at the moment on only 5psi of boost. maybe with slicks and wide tires on a drag strip. but as a useable car.... no chance.

other then maybe anti lift devices (only good for starting really which the centos will never be good at anyway) my car has every suspension mod available and not available. it handles amazingly well but the power can upset things so quickly.

the only thing I am thinking of doing that will let me run more boost without killing the car is to let the ecu take control over boost. and only letting boost go above 5psi when above 3rd gear and more boost at higher rpms.

 

[fingers99]

the most economic route would be just buy a set of t-jet pistons. there is not much of a t-jet that would fit. by the time you have it so it fits in the cento it may aswell be a normal 1.4 with t-jet pistons.

Nah. The Polskis have pretty much proved it can be done "just" by fabricating new manis. Not sure which gearbag they were using, though. The Abarths (and Mito) use a tougher box which is said to be dimensionally larger -- there may be space issues.

other then maybe anti lift devices (only good for starting really which the centos will never be good at anyway) my car has every suspension mod available and not available. it handles amazingly well but the power can upset things so quickly.

I've a hunch that the lift is combined with some pretty unwanted geometry changes and that these are what makes the cars so difficult. I've yet to use a jack and some guages to determine this, but it's certainly what it feels like. Rather than the passive anti-lift stuff the VW folk use, I was thinking of something that stiffened up the dampers (something like the ones with iron filings in them) around the torque spike -- and you could do it at both ends. Other than that, it's down to very serious engine and turbo development to remove the spike.

One of the cars featured in the Street Turbocharging book is a Mk1 MR2 with the formerly supercharged (JDM) 1600 engine fitted with a T25. Compare the torque curve to that the Cento tubs put out.............

 

[craigb244]

Nah. The Polskis have pretty much proved it can be done "just" by fabricating new manis. Not sure which gearbag they were using, though. The Abarths (and Mito) use a tougher box which is said to be dimensionally larger -- there may be space issues.


I've a hunch that the lift is combined with some pretty unwanted geometry changes and that these are what makes the cars so difficult. I've yet to use a jack and some guages to determine this, but it's certainly what it feels like.

the engine also has so big bits on the cambox and cam... bit like the 1,4 NA
also the oil pump/oil cooler won't fit so will need changing to a normal 16v one and your own oil cooler setup


explain this hunch! I did the tracking on my car with a proper computer controlled laser alignment system at my dads work... when the car was lifted nothing happened to the tracking that was out of the normal at all. if you tell me what to look for I can get any details you need down to a micro degree lol well next time I do the tracking anyway

 

[fingers99]

Camber and castor changes, methinks. I'm sure he of the V70 (can't remember his name) actually had pretty significant suspension changes, like moving the pick ups. I'll do a search (anything to keep me out of the cold, working on the P100...............)

 

[fingers99]

Ah, StoneNewt. Duty calls. I may be gone for some time.................

 

[woj]

also the oil pump/oil cooler won't fit so will need changing to a normal 16v one and your own oil cooler setup

My argument is probably not fully valid here, because Seis have considerable more space than Cinqs. But, at least two of the t-jet projects in PL (both Seis) kept the t-jet oil cooling equipment. One more that is on the way will keep it too. Not easy though, needs a bit of trickery, putting the rad forward a bit, etc.

I am most certain of one thing: if I ever am going to do another small Fiat project, it is going to be on the t-jet base. I am in progress of learning things I need to learn and collecting pictures.

Craig, you also mentioned t-jet docs you cannot share. Is that a pdf file called training manual something that was once downloadable from a website in Austria?

 

[craigb244]

My argument is probably not fully valid here, because Seis have considerable more space than Cinqs. But, at least two of the t-jet projects in PL (both Seis) kept the t-jet oil cooling equipment. One more that is on the way will keep it too. Not easy though, needs a bit of trickery, putting the rad forward a bit, etc.

I am most certain of one thing: if I ever am going to do another small Fiat project, it is going to be on the t-jet base. I am in progress of learning things I need to learn and collecting pictures.

Craig, you also mentioned t-jet docs you cannot share. Is that a pdf file called training manual something that was once downloadable from a website in Austria?

I think the cooler (at least for me) would require the turbo to be off-set towards the gearbox a bit (not a problem really as the manifold will be custom anyway) ALSO I think there might be a bit of a clearance issue with the wheel if you use wide enough tires.

not sure on the documents. I was given them

 

[fingers99]

ALSO I think there might be a bit of a clearance issue with the wheel if you use wide enough tires.

Tyre and T Jet box may be an issue. But it seems there are bellhousings available to use the n/a gearbag instead.

 

[craigb244]

I was talking about the oil cooler

Anyway....
Had a bit of an issue.... last few days my car was smelling fumey inside and slowly getting worse.

turned out the drain i hit it town pulled the section apart under the car (need to go back to where i had the exhaust made and have it extended a little as ii cant get it all fitted together perfect due to position changes with the new engine)

BUT also had a leak where the core fits into the turbine housing! (bottom of the turbo was black with soot )

simple fix i thought.... removed the 4 10mm bolts holding the core to the housing and reseat it all...

if only! 2 of the bolts snapped off instantly! Bugger! (no idea why! they have only been there a few weeks!)

that meant removing the whole turbo from the manifold (not easy)

luckily i managed to build some weld up on the bolts that that luckily had snapped flush and not inside the holes and remove the remains.

also found the reason it never seated.... a TINY blob of steel (most likely from weld) has wedged itself into the corner of the grove where the turbo core seals on housing (there is no o-ring or anything just two flat surfaces)
this held apart at the bottom allowing exhaust gasses to leak.

No damage done... just turned a hour job into a 8hour job (checked and the turbine has never contacting the housing)

Good thing is now the boost comes in even smoother and starts about 500rpm lower.
and a strange buzzing sound when letting off the throttle after been on boost has vanished

Yippy

 

[fingers99]

Ah well, one step backwards, two steps forwards.

Wonder if the bolts just lost temper (or even became embrittled) due to the heat? Can't think of a solution, though.

 

[craigb244]

mmmm maybe but they are originals so surely designed to take the heat... (and this is a petrol turbo not a diesel)

I think it could of been that they have been under extra stress from the flat surfaces not sitting on each other. maybe allowing the core to "rock" on the housing. the two that snapped where both on the same side.

they really dont hold much. only tiny little 10mm bolts with a very short thread

 

[blu73]

surely with the heat going through them they could've bent ever so slightly. Meh its fixed now

Also, here is a major difference between you and me, if that happened to me i would have spat my dummy out and left it for the day lol