Tuning turbo time!

[Todger182]

Nope, they were 1.4 pistons.

They are bigger than the 1.2 ones are we measured them a while back just to see how much of a difference in size there was. Very little .

Also one thing that was interesting was the amount of dish on the 1.4 pistons, they have a much bigger dish than the 1.2 pistons aswell so the power purely comes from the stroke. Compression on the 1.4 engine must be very low .

Thanks

X

 

[whitz]

Nope, they were 1.4 pistons.

They are bigger than the 1.2 ones are we measured them a while back just to see how much of a difference in size there was. Very little .

Also one thing that was interesting was the amount of dish on the 1.4 pistons, they have a much bigger dish than the 1.2 pistons aswell so the power purely comes from the stroke. Compression on the 1.4 engine must be very low .

Thanks

X

1.2 16v CR is 10.8:1
1.4 16v CR is 11.1:1

Ash

 

[Todger182]

I stand corrected, the fiat 1.4 comression is higher than the pugeot 1.4, and also higher than a VW 1.4.

Still though, the piston has a rather large dish, but may be generic so that they can be adapted for the tjets.

Thanks

X

 

[Munkul]

remember its about the ratio of swept volume to combustion chamber volume, so if fiat made the head chambers the same volume as the 1.2 then the pistons would have to be lower like you say they are, to keep the CR from being too high

 

[craigb244]

Rods, not pistons. And then (talking of engine builders in general, no-one in particular), it'd depend how much of the engine you were building. Reputation means an aweful lot if that's all that puts the food on the table.

Todg, I'm pretty sure those pistons were 1.2 ones -- the ones that cracked due to det (we think)?

At the end of the day I'd like a Cinq tub that can fight duels with 7 series BMWs, win, and not leave oil over their windscreen............

sorry I ment rods.

I spoke to todger about them cracked pistons. iirc it was hydro locked by extreme over fueling caused by learning how to use mega squirt the hard way lol

 

[fingers99]

I think hydrolocking would bend rods. At the time, we diagnosed det. BWTH. Kris didn't wreck 2 sets of pistons, did he?

 

[randomizered]

I only killed one engine, a 1.4. The 1.2 was fine and was sold. When I killed the 1.4, I had it rehoned, put in brand new fiat pistons and rings, and built it back up. It blew a bit of oil, so i replaced the whole engine.

Todger now has that block and has had it checked out again. The builder said it was just the rings not bedding in :bang:

The 1.4 pistons that went, I'm pretty sure it was det that dit it, not hydrolocking. That engine went through LOADS and LOADS of abuse though before giving up. I ran advance up to 40 degrees on cruise, I leaned out to 17-18 afr at points, I ran up to 7,600 rpm and took it there often trying fuel cut and spark cut rev limits. I gave it a lot of stick and it took a long time to blow. WHen it did it was mighty impressive I knew it would at some point as I wsa experimenting a lot.

I personally think the piston on most of the fire series is the weakest point, but thats personal opinion with no real basis.

Each to their own, do it on the cheap, or do an expensive job. We can still all be friends

 

[Todger182]

Only thing that was worn in on that engine was the big end bearings, which are due for renewal .

Those pistons were FUBAR .

Thanks

X

 

[Munkul]

Interesting

Kris yours was just n/a though wasnt it? So you wouldnt be putting the same compression forces on the rods as turboing would, just more force from inertia from the higher rev limit? Guess the rev limit also helped the big ends away as well?

 

[randomizered]

Cheers for the name edit

Yeh, N/A. I imagine turbo forces overall would be a lot greater then N/A. When det occurs you get about 20X chamber pressure, so that would have sent a lot of energy elsewhere (apart from the lands lol).

Who's bent a rod in a fire engine? I seen some coupe's throw rods, but not many of ours, seems more often pistons and gaskets regardless of the application.

 

[Munkul]

I know a few Kris's and Cristian's, for some reason I thought I remembered you being a Cristian its far too late lol

Aye strangely enough although the rods are supposed to be weak, Ive never heard of one bending yet... suppose theres always a first though

 

[Westwood172]

How hard would it be to turbo the 1.6 sporting? And donu know where I can find replacment engine

 

[fingers99]

The 1.6 Sporting? The Punto engine? No real point in doing that to a Cento.

 

[fingers99]

Each to their own, do it on the cheap, or do an expensive job. We can still all be friends

Amen to that!

 

[craigb244]

Fingers.... I think I have found the weak rods you talk about!

mk1 punto 16valve has rods which are normal cast jobbies with normal cut big ends.
BUT they are much much thiner then the 8valve rods. they dont have much of a H pattern either (unlike the new 16valve rods which are very "curvy")

the gudgeon pin is the same size as the 8valve rods.

the piston looks a bit rougher around the edges compared to the modern pistons.

looks to me like fiat built these 16v engines to a budget as i guess the 16valve in the mk1s where still in prototype/trial stages.

if anyone is interested illl take photos and weights.


oh and one more thing i should mention. I think the 8valves changed their gudgeon pin sizes at some stage to the same as the 16valve.
I just took a 8valve piston off its rod and found them to be the same... cant recall what engine it was from.
But i know for a fact the 8valve rods I took apart in the past to balance them had a pin that was about 1mm smaller

 

[randomizered]

Photo's are always interesting, so if you get chance I'll be interested

 

[craigb244]

Notice that the old 16valve rod has the sides of the small end flattened. very strange and looks like a huge weak point to me.

 

[randomizered]

Very interesting, cheers

 

[fingers99]

Late 16v rods would make an interesting comparison.

 

[craigb244]

the left rods are the late rods. I have 3sets from all different years and they have all been the same so bet even the latest have the same rods.

only the first 16valves with the sump that is the same as the 1.2 8valve have the normal cut but thin rods