forged pistons and or decomp

18th December 2011, 14:55

bought a boosted car recently, went ver very well indeed!

was tiold the engine (vtr) had forged pistons and rods, breaking the car down today realised theses 2 head gaskets either side of what looks like a decomp plate,

whats the likelyhood of it having the pistons and rods? i think unlikely as the pistons alter the comp dont they alone?

stew

18th December 2011, 15:04

Id say very unlikely its got pistons n rods

Pistons with the right headgasket will be low comp enough

18th December 2011, 15:59

why would the person use 2 HG's and a decomp plate, id find it unlikely that it'll have the pistons could have rods tho only way to find out is to take the sump off

18th December 2011, 16:25

yes true lads,

one thing for sure it went well, very well. the car had been built in 2006 and lasted this long, the charged engine was miles quicker than my vts/cams/bodies!

i have no use for the vtr engine. i may offer it for sale as is, after all its handled power for so long etc, or i can split the engine and take a look to see what its got.

whats it worth as is? mk1 98 vtr engine was running 170atw! 200ish flywheel.

ive also got mf2,dastek, 5th inj, map sensor and some pipework for sale.

18th December 2011, 19:58

dont think many saxos built back then would have been forged, the cost of the conversion alone would have been stupid money back then, ppl used to use decomp regular back then going off other projects ive seen

you got dynos for that too mate ? figures seem quite high for a s/c vtr, most of them ive seen have been about 150-160bhp, just curious seeing as it was stil on mf2

not seen too many s/c vtrs, used to be really common as vts were daft prices back then aswell lol

18th December 2011, 22:25

it could of been forged andrew, mine was forged and had a decomp and that was in 2004

18th December 2011, 22:38

Oh I know Martin, but it's gmc built so I'd have thought John would match the pistons and gasket to the CR, so decomp and 2 gaskets I'd have thought no, but as you said, could still be, won't know without looking tbh

19th December 2011, 01:31

Is it a good idea to run a 2mm decomp with 2x 0.6mm gaskets off of gmc?

19th December 2011, 16:31

It would have to be running 1bar of boost to be significantly quicker than Stew's 'bodied 16v, which makes 150+bhp crank, it'd need to be up in the 170-180 ergion for Stew to say it's 'significantly quicker', so running a bar of boost IMHO giving it 180-200bhp crank

19th December 2011, 17:09

lads i was told the car was running just over 170, i presume atw? as its way quicker than mine, far more than 20brake. previous owner did not have any paperwprk with the car.

and the vtr it came from was a heavy full car with rear brakes binding as it was stood for a long time.

19th December 2011, 17:11

hang on a min there too, we may be talking bhp figures here but its more likely to be the torque thats a lot more than my bodies vts?

19th December 2011, 19:16

I was gonna say as I was reading my way through... Turbo is going to have a load more mid range where you'll feel like it's toasting your N/a engine. Peak power could well be the same, just the turbo has a huge slug of torque below that.

19th December 2011, 19:36

id iexpect a supercharged vtr on 150bhp to piss allover a bodied 16v making 150bhp(just comparsion figures)

the torque will be far greater, and come in much lower down the rev range

more so with a turbo..

19th December 2011, 19:43

This is what pisses me off with people saying "ma car haz 150 hp from ph3'z", or similar. That's great, but there's bugger all torque 2000 rpm below that figure.

19th December 2011, 19:56

thats where turbos rule tbh

could boost a vtr on super low boost, making say 140bhp @fly with a nicely matched turbo for instant spool, if it makes 140bhp under 3k rpm its gonna smoke a 16v on bodies that makes 150+bhp at 6-7k+

its still gonna get more torque all the way through the revs aswell

19th December 2011, 20:08

wont forgies be dished?

19th December 2011, 20:11

yeah if theyre low comp but i dont know if hes splitting the engine to find out

its also possible that its running hi comps with a decomp plate to bring it back into the right CR

19th December 2011, 21:59

My thought tbh, cheap set of used high comps to take the heat, with a decomp to lower cr....

Should split and find out.

20th December 2011, 07:43

Was this the silver vtr that was on pistonheads for sale up near Glasgow? If so I hope you cut a good deal with the lad since it had been for sale on and off for a year

20th December 2011, 10:03

I did well thanks

20th December 2011, 10:04

Quote:

Originally Posted by Dboyvts

Was this the silver vtr that was on pistonheads for sale up near Glasgow? If so I hope you cut a good deal with the lad since it had been for sale on and off for a year

yes it is. from near lanark i'm sure. my mate was thinking of buying it to put the engine in his gti

20th December 2011, 10:09

vtr +1bar s/c will be around 170bhp --but will feel more as it gives the bhp over a wide range and at lower rpm than a 16v.
I still see no reason for running decomp plates as you can use multiple MLS gaskets with no problems at all + its cheaper .
just go round h/bolts 3 times with ten minutes between when checking inital torque up of 20nm,s - before you do the angular torque of 260 degrees-you can go to 270 with no problem --thats the setting for the diesel version --so well within normal tolerances
-.
I just don,t like the decomps as there is no REAL sealing going on
--with mls gaskets they have a viton coating ,so provided block + head faces are CLEAN+ DRY the viton will bond everything together

"wellseal" which is what you should use with decomps to the block was made really to seal liners that move about all the time,thats why it does not set --not so with a cast block ,its also not cheap stuff
I cannot imagine why this car was lowered so much .other than it did not have any mods to igntion curve --which on a s/c car is no where near as critical as a turbo due to the way the boost comes on and you cannot have same boost at low rpms as you can with a turbo--hence comp ratio does not need to be as low

20th December 2011, 17:29

i will take a few pictures of the block and show what i can see at the weekend

there is a bronze like coloured thick gasket between two mls gaskets.

20th December 2011, 18:08

Sounds like a copper or brass decomp, were quite common before price of metal rocketed, copper more common, ferridays used to sell the copper ones iirc

20th December 2011, 18:36

Im going to shine a light down the plug holes. Wonder if i can see non standard pistons. Other than that will be up for sale.

20th December 2011, 20:06

If you think you'll use it, get yourself a borescope off eBay, can get th for about 30 quid, don't get one of the USB ones they're huge an useless, quite handy to have and always usefull for checking engine damage without removing heads etc,

20th December 2011, 20:12

ive heard of them never seen them

20th December 2011, 20:31

something like this one would be ideal...this is a usb one, but not as bad as some of them and is pretty cheap
http://www.ebay.co.uk/itm/Mini-Endos...ht_3798wt_1037

looks like the lcd screened ones are about £50 now

20th December 2011, 21:53

Quote:

Originally Posted by blackie_2k5

Sounds like a copper or brass decomp, were quite common before price of metal rocketed, copper more common, ferridays used to sell the copper ones iirc

mine was the 1st ferriday TU one and its copper (thats why im using it instead of a head gasket on the 16v head) so if its a ferriday one it would have to of been built after 2004

20th December 2011, 22:27

Was built 06 mate, I think

20th December 2011, 22:38

What size/model charger dose it have. The pics I seen did not show an oil tank for the charger so I was thinking it was quite an old kit.

21st December 2011, 07:26

3074 it has an oil tank for charger and cooler

21st December 2011, 20:31

bore-scopes are very useful bits of equipment. If working alot on engines (diagnosing faults) then there almost essential. I use on almost every week at work

21st December 2011, 20:39

i used to work as a builder before i got a lazy mans job

used to use one regular for checking cavity walls etc, testing concrete and stuff, conpany had one that cost a small fortune, can lend that whenever so ive never needed to buy one, but they are really good items to have

22nd December 2011, 19:48

just had an idea to get an estimate on power...

the charger pully on the rotorex c3074 is 75mm. i do have a spare 80mm pully.

what boost are these expected to give?

25th December 2011, 11:05

what i think may be a decomp?

25th December 2011, 12:00

Does look like decomp to me

25th December 2011, 20:04

was looking at this earlier but couldnt make it out on phone

does look like a decomp & MLS

25th December 2011, 20:15

Yeah its the 1st one ive seen in the flesh. Kind of obvious as the heads higher than normal off the block.

25th December 2011, 20:31

if you look round the back of the block...it should probably stick out fruther then the gasket should, id pretty much 100% say thats a decomp and mls..but itll give you further proof without splitting the lump

25th December 2011, 21:33

id like to find if it had forged omega pistons as i was told when i bought it, ill take a look down the plug holes if i can.

whats it worth with the pistons and with just a decomp?

i am confident it has them tho as it was built in 2006 and i have seen its done 13k since charger and rebuld was done.

25th December 2011, 21:44

id be really surprised if it had low comps and a decomp tbh mate, it has been done before as posted in this thread...but on a s/c you dont have to lower the CR as much as a turbo anyway... so itd probs be very low CR

as for value its hard to say...without an engine spec you know nothing...aswell as were talking an engine that was allegedly built a while back, you can see its only done X amount of miles since build...but thats only what the clocks tell you, could have had 5 sets of clocks in since and alot of miles.... with little history this puts ppl off

if its decomp only engine its worth about as much as second hand decomp really, as before you know so little about it...aswell as what CR its even running, so id imagine it would put alot of ppl off again and be really hard to sell as a whole, probs about £100max to someone whos loking to budget boost super cheap.... a new decomp can be got for not much more but youve got top end rebuild parts on aswell...

its a tough one really mate

25th December 2011, 22:04

ive got mot milage proof

engine is still in i guess i could do a compression test?

i can honestly say it went very well, didnt smoke under any conditions and started/idled well and strong from cold. i have some footage of it running etc... better than nothing at all i suppose.

25th December 2011, 22:06

mot papers from 2005 for every year may i add.

25th December 2011, 22:14

but is it the same engine, if its supposed to have low comps then its quite possibley not

more investigation needed mate, see if you can find someone with a borescope..

cant remember if you can see the back of the pistons on these via taking the sump off or not..sould be another option..just cant remember if you can see them properly or at all with just the sump off..

25th December 2011, 23:22

Could he not do a 'feel' check by placing a screw driver down the spark hole and feel for the lip you get on lo-comps?

26th December 2011, 04:34

Quote:

Originally Posted by Barry123

Could he not do a 'feel' check by placing a screw driver down the spark hole and feel for the lip you get on lo-comps?

Would be too tight to do that.

Just pull the head off - any buyer would replace the cambelt anyway. Plus definitely knowing its got forgies turns a 50quid engine into a 300+ engine

26th December 2011, 09:00

True

26th December 2011, 09:46

Quote:

Originally Posted by sexy_gt

id like to find if it had forged omega pistons as i was told when i bought it, ill take a look down the plug holes if i can.

whats it worth with the pistons and with just a decomp?

i am confident it has them tho as it was built in 2006 and i have seen its done 13k since charger and rebuld was done.

two ballons + goldfish
.
why would you fit forged pistons+rods
+then they go and fit decomp plate + a very thick gasket.
its worth same or less than a std 1.6 8 valve that no one can hear running --as you have ripped all the bits off it.
If you really thought it had them then you would be lifting the head and just fitting your 16v head to that block + the s/c job done
I certainly would not buy it without seeing the head off ,as not only will you see how good the engine is ,but you will see if the pistons are omega,so common sense says lift the lid and have a look

26th December 2011, 10:27

Quote:

Originally Posted by axsaxoman

two ballons + goldfish
.
why would you fit forged pistons+rods
+then they go and fit decomp plate + a very thick gasket.
its worth same or less than a std 1.6 8 valve that no one can hear running --as you have ripped all the bits off it.
If you really thought it had them then you would be lifting the head and just fitting your 16v head to that block + the s/c job done
I certainly would not buy it without seeing the head off ,as not only will you see how good the engine is ,but you will see if the pistons are omega,so common sense says lift the lid and have a look

wasnt aware of the decomp when i bought it or you can fit 16v head on an 8v just like that?

if thats the case then ill have head off and see for myself and if its as simple as you say then ill fit a 16v head. providing the right pistons are there.

26th December 2011, 17:24

the only thing that needs doing to fit a 16v head on an 8v block is the extra drilling for the cambelt guide pulley

27th December 2011, 15:02

liftted the head off today

OMEGA 78.5

Looks like thers been a plug tip or something lost in the middle two bores at some point.

piston on the right looks like its been very hot at some point!

when i turned the head over i found the plug for the piston above had melted most of the tip and was only in by 2-3 threads. it has been working its way loose.

heres the head... looks like standard valves to me.

must say the throttle body and inlet ports was super clean, almost polished they are that shiney!

the gasket that had some of us fooled

its a millen brand (something like that)

no seperate decomp just a very thick part.

clutch had seen better days

if the pistons are in there then i dont see why the rods wont.

27th December 2011, 16:52

if you whip the sump off you can tell by the look of the rods what they are

pistons have seen better days and thats not the 1st helix ive seen shit itself

27th December 2011, 18:30

Is good that it had pistons in there - looks like it could do with a good mapping to be fair as that piston on the right doesnt look ideal !!

27th December 2011, 18:42

Wahey, score tbh mate, fuck me that clutch is nailed, was it drivable like that?

Definitely been super hot but doesn't seem to have caused tooo much damage, get the pistons cleaned up and do some more investigation

Id really recommend a rebuild on that to be safe mate, looks like its had some serious abuse

That's the thing with pictures you jus can't always get a clear image, but least you have answers now

Edit- that's also a downside to mf2, you can never be sure the fuel mix is dividing to each cylinder in equal portions, so you can never be sure your getting good afr's across the bores 100% of the time

27th December 2011, 18:53

that piston thats scabby is the one where the spark plug was about 10mm recessed into the head, not above the piston like it should be.

they do look like they have been to hell and back lol.

can we agree that the dents on the two middle piston heads are from a plug tip not the results of det?

also i should check spark plug grade.

the sump has to come off as ive a baffle to fit

27th December 2011, 19:07

are you planning on running them pistons ?

27th December 2011, 19:13

yes i am

27th December 2011, 19:15

You lucky thing! Stripping an engine to find out it HAS got a forged bottom end!
Lucky thing lol

27th December 2011, 19:16

Quote:

Originally Posted by Beaniemoo

You lucky thing! Stripping an engine to find out it HAS got a forged bottom end!
Lucky thing lol

it was sold as a forged engine tho.

27th December 2011, 19:17

So was mine lol

27th December 2011, 19:24

Quote:

Originally Posted by Beaniemoo

So was mine lol

yeah i see what happened, unlucky.

28th December 2011, 09:41

Those pistons look haggared. The dents in the top of the are a perfect spot for det to occur from due to them being hot.

Cant really see from the pistons too well, but the edges of the pistons look nackered too around the crown and around the piston recess. Wear/chips off the edges of pistons are a common sight with an engine which has been knocking before. As the shockwave caused by uncontrolled combustion reflects back off the cylinder wall, so the edge of the piston receives double the amount of shock as the other areas of the piston.

If I saw them in an engine I was having built I would instruct they be used as paperweights.

28th December 2011, 09:58

pistons look like old damage --just too lean --maybe been stripped before and cleaned up+ new rings .
If engine was running fine and no heavy breathing ,then don,t strip it .
the pistons are really buggered ,so no point ,if they are happy now just run them --nothing to loose .
If they were damaged + not cleaned up there would be marks on the bores now
there must be at least vts rods in it as the vtr rods are not fully floating .
run it til it blows --maybe with correct fuelling it will stay together--make it plenty rich --this is presuming that it was NOT breathing before you stripped it and as there is no signs of fresh oil on top of pistons it would look like it wasn,t running that bad.--maybe just wrong plugs fitted which burn,t the tips off and started the problem

the clutch --just plain worn out --check the splines(look very worn) and the fingers have probably gone due to wrong release brg fitted --or maybe just not up to the power it had in the first place --bin it and start again

28th December 2011, 15:55

i plan to use bottom end as it is + i must fit a baffle. i think i need to fit a vts sump as there is a sensor in it.

can i do that?

also head gasket, are vtr and vts the same? as im using vtr bottom end and vts head...

it was running well, there was no oil on top of pistons, just some black deposits. little bit sticky but not thick. not quite dry and carbon like.

im not asking this to run megga power just 1 bar from a c3074. as it was before but with 16v head.

clutch/ yeah ive budgeted for a new one.

28th December 2011, 19:42

WOW- they look alot worse on laptop then they did on my phone lol, looks like a few of them have suffered some meliting/det at some point

i retract my previous statement about a rebuild, it wouldnt be worth the money it would cost you for one of them to shatter or crack, i bet youll still get a fair few miles out of it before it gives way..

however if it has got rods in...it may be worth you splitting it to rebild another lump with the rods as theyll probs end up fucked if/when it does burst

so would save you buying more for a new engine???

28th December 2011, 19:49

Im running this till she pops. Ill build a new one then.

Its going to be interesting how it lasts with a proper good map.

28th December 2011, 20:01

get it mapped rich like john said, should help it run a little bit cooler

i think itll probs last a fair bi tbh mate, if its been running well like that then it should get a few more miles in before it pops

probs wouldnt last very long if it was turbo like.. but being s/charged will help a bit

28th December 2011, 20:05

Quote:

Originally Posted by blackie_2k5

get it mapped rich like john said, should help it run a little bit cooler

just dont have a bonnet on, itll be alright

28th December 2011, 20:06

Quote:

Originally Posted by Dean-VTR

just dont have a bonnet on, itll be alright

external cooling is good....internal cooling is better