534 replies to this topic

[techieboy]

that may explain your orignal problem Matt...

Quite.

[The Batman]

Well
there's no reason why you can't rune the harrop on high comp pistons, absolutely none. It just needs some mapping

when i was rebuilding the engine again, i suggested skimming the head to gain some compression back but apparently when speaking to Jon it was an absolute NO NO!!

[Exmantaa]

Well
there's no reason why you can't rune the harrop on high comp pistons, absolutely none. It just needs some mapping

your main restriction on your engine will now be the SC heat (due to the small pulley); maybe you'll have 290 on the dyno with a 3" exhaust but after a few pulls/laps not sure it will be the same...
Higher comp + smaller pulley is always the smarter way to go

(As a side note, I work a bit on a full race M62 build for a friend, and we did some 170°C expansion tests on the 8.9 Wisecos... when I said Wiseco suggested bore to piston clearance is way too small, I was more than right )

You mean higher compression and a bit larger pulley is the smart way to go...

But reading all your remarks here, why are you then building an M62 build with 8.9 "low" compression?? Or was that just to test the material expansion?

Edited by Exmantaa, 07 October 2009 - 02:57 PM.

[alanoo]

As a side note, I work a bit on a full race M62 build for a friend, and we did some 170°C expansion tests on the 8.9 Wisecos... when I said Wiseco suggested bore to piston clearance is way too small, I was more than right

Okay, do you want to expand on that a little bit? Am just about to take delivery of another set of Wiseco pistons and Eagle rods and will shortly be taking the new cylinder block off for a rebore. I can't afford (mentally or financially) to get it wrong again.

Expansion is measured at 120 µm at 170°C (block at 80°C)

I think the wiseco suggested clearance on the small paper coming with the pistons is 65µm
If you mail them and talk about a track application they will advise you around 95 µm

There's 20 µm of graphite coating by the way too which gets away after a few miles, so a clearance of 100 to 110 µm should be perfect... maybe 90-100 for less extremes applications (not a full track car), less would be bad...

[Crazyfrog (Fab)]

Well
there's no reason why you can't rune the harrop on high comp pistons, absolutely none. It just needs some mapping

when i was rebuilding the engine again, i suggested skimming the head to gain some compression back but apparently when speaking to Jon it was an absolute NO NO!!

so you need to buy a new head i will discard your old one lol

[alanoo]

Well
there's no reason why you can't rune the harrop on high comp pistons, absolutely none. It just needs some mapping

your main restriction on your engine will now be the SC heat (due to the small pulley); maybe you'll have 290 on the dyno with a 3" exhaust but after a few pulls/laps not sure it will be the same...
Higher comp + smaller pulley is always the smarter way to go

(As a side note, I work a bit on a full race M62 build for a friend, and we did some 170°C expansion tests on the 8.9 Wisecos... when I said Wiseco suggested bore to piston clearance is way too small, I was more than right )

You mean higher compression and a bit larger pulley is the smart way to go...

But reading all your remarks here, why are you then building an M62 build with 8.9 "low" compression?? Or was that just to test the material expansion?

Yep larger pulley, smaller boost

Well, this build is limited by the regulations of the trophy he is racing in, aim is only 250 hp. Originally it was one of the 3 firsts Hitec conversions ! (so with the decomp plate), so even 8.9 is still a lot better than with the plate.
Were the cheapest "boost" pistons, and well now that we know the real expansion, shoud have no issue.
We tested it because from various sources we had bad feedbacks about Wisecos expansions, was just to check

[The Batman]

exactly so lower compresssion more boost, higher compression less boost. so if you get low compression pistons then you can get a harrop and increase the boost, however if you get higher compression then get a harrop you will have to limit the boost.... so from that i assume if you want more power then lower compression is the way to go... but if you just want to keep the m62 then higher compression is the way to go, correct?

[techieboy]

As a side note, I work a bit on a full race M62 build for a friend, and we did some 170°C expansion tests on the 8.9 Wisecos... when I said Wiseco suggested bore to piston clearance is way too small, I was more than right

Okay, do you want to expand on that a little bit? Am just about to take delivery of another set of Wiseco pistons and Eagle rods and will shortly be taking the new cylinder block off for a rebore. I can't afford (mentally or financially) to get it wrong again.

Expansion is measured at 120 µm at 170°C (block at 80°C)

I think the wiseco suggested clearance on the small paper coming with the pistons is 65µm
If you mail them and talk about a track application they will advise you around 95 µm

There's 20 µm of graphite coating by the way too which gets away after a few miles, so a clearance of 100 to 110 µm should be perfect... maybe 90-100 for less extremes applications (not a full track car), less would be bad...

All of this sh!t is way over my head but.....

Just checked the spec sheet that come with them and the Wiseco "suggested" clearance 0.0025 Inches (63.5 Microns). So should I be telling the machine shop to do it at something more like 0.0035 Inches (88.900 Microns). Wouldn't that increase the likelihood of higher oil consumption, blow-by, etc? I thought one of the benefits of forged pistons was the metal composition not being as susceptible to thermal expansion as well as being stronger and more resistant to detonation?

Do you reckon that the smaller clearance might have been part of my issue with the original engine, especially the two "polished" sections on each cylinder wall?

[NickB787]

As a side note, I work a bit on a full race M62 build for a friend, and we did some 170°C expansion tests on the 8.9 Wisecos... when I said Wiseco suggested bore to piston clearance is way too small, I was more than right

Okay, do you want to expand on that a little bit? Am just about to take delivery of another set of Wiseco pistons and Eagle rods and will shortly be taking the new cylinder block off for a rebore. I can't afford (mentally or financially) to get it wrong again.

Expansion is measured at 120 µm at 170°C (block at 80°C)

I think the wiseco suggested clearance on the small paper coming with the pistons is 65µm
If you mail them and talk about a track application they will advise you around 95 µm

There's 20 µm of graphite coating by the way too which gets away after a few miles, so a clearance of 100 to 110 µm should be perfect... maybe 90-100 for less extremes applications (not a full track car), less would be bad...

All of this sh!t is way over my head but.....

Just checked the spec sheet that come with them and the Wiseco "suggested" clearance 0.0025 Inches (63.5 Microns). So should I be telling the machine shop to do it at something more like 0.0035 Inches (88.900 Microns). Wouldn't that increase the likelihood of higher oil consumption, blow-by, etc? I thought one of the benefits of forged pistons was the metal composition not being as susceptible to thermal expansion as well as being stronger and more resistant to detonation?

Do you reckon that the smaller clearance might have been part of my issue with the original engine, especially the two "polished" sections on each cylinder wall?

I don't know what clearance they used when Courtenays got mine rebored but maybe worth a call?

[alanoo]

All of this sh!t is way over my head but.....

Just checked the spec sheet that come with them and the Wiseco "suggested" clearance 0.0025 Inches (63.5 Microns). So should I be telling the machine shop to do it at something more like 0.0035 Inches (88.900 Microns). Wouldn't that increase the likelihood of higher oil consumption, blow-by, etc? I thought one of the benefits of forged pistons was the metal composition not being as susceptible to thermal expansion as well as being stronger and more resistant to detonation?

Do you reckon that the smaller clearance might have been part of my issue with the original engine, especially the two "polished" sections on each cylinder wall?

not necessarily massively increased blow by/oil if the ring end gaps are done correctly (but always higher than with stock pistons).
Main "risk" is piston slap why low temperatures

Lot stronger and more resistant to detonation but expands a lot more.
Well not exactly true, yes the 2618 alloy expands lot more than other ones (very low silicon %), but the design is much more important than the material choice and that's why Wisecos are worse than other ones.
For example, Diamonds are 4032, which expands less + are better designed so you could use a smaller bore to piston clearance and that with the lower expansion will lead to smaller oil consumption

[Exmantaa]

not necessarily massively increased blow by/oil if the ring end gaps are done correctly (but always higher than with stock pistons).
Main "risk" is piston slap why low temperatures

Lot stronger and more resistant to detonation but expands a lot more.
Well not exactly true, yes the 2618 alloy expands lot more than other ones (very low silicon %), but the design is much more important than the material choice and that's why Wisecos are worse than other ones.
For example, Diamonds are 4032, which expands less + are better designed so you could use a smaller bore to piston clearance and that with the lower expansion will lead to smaller oil consumption

Thxs for the info. Diamonds "9.5-ish" it will be then for me.

[mandarinvx]

(note to next SC guys : Diamond racing have some very nice 9.5:1 pistons for the 2.2... forget Wisecos !)

Do you know if they are still trading? It looks as though their website hasn't been updated for a few years, and the contact number given is dead I've tried emailing just in case

[mandarinvx]

I've found the catalogue page but neither of the numbers at the top of the catalogue seem to work Anyhoo:  Pistons.jpg   95.25KB   6 downloads So they are standard size 86mm, does this mean that new liners need to be fitted (as advised on Allecotec when using stock sizes) or will they be ok as a direct replacement without having to remove the block

[Crazyfrog (Fab)]

need to put a stop on tuning all those shiny parts

[alanoo]

I've found the catalogue page but neither of the numbers at the top of the catalogue seem to work


Anyhoo:

 Pistons.jpg   95.25KB   6 downloads


So they are standard size 86mm, does this mean that new liners need to be fitted (as advised on Allecotec when using stock sizes) or will they be ok as a direct replacement without having to remove the block

normally available at 86.50 too for the same price + other CR

Don't know if they are still trading or not in fact, but didn't read anything saying that... don't know

Otherwise Wossner in germany have experience with pistons for our engines, more expensive but much better quality

[mandarinvx]

need to put a stop on tuning all those shiny parts

One day I may actually get round to fitting them

[mandarinvx]

normally available at 86.50 too for the same price + other CR

Don't know if they are still trading or not in fact, but didn't read anything saying that... don't know

Otherwise Wossner in germany have experience with pistons for our engines, more expensive but much better quality

To put it a slightly different way ()

Is there any way to fit replacement pistons / rings without removing the entire engine and sending away for machining, whilst retaining reliability / performance

[techieboy]

When I was looking at the Diamond pistons a month or so back, I was going to get them through this lot along with a couple of other bits. Decided not to as the pistons alone came to the same amount as the Wiseco/Eagle combination from allecotec.

[Exmantaa]

As these seem to be made for the 2.0LSJ's rods, do they actually fit our 2,2 + eagle rods?

[alanoo]

The .787 pin one is normally the good one