8v head spacer for turbo

[beavy69]

Anyone know where I can get one?

And if I dont have to get it specially made, what thinknesses do they come in/will I need?; as I am planning to use it to up the cc of my 1.3 for an m-vaux 1.6 8v turbo kit conversion running with an irmcher 1.3 injection system. :thumb:

[Mike]

there about 1.5mm thick IIRC when used on a 1.6 engine with a twin headgasket setup, so would need to be more on a 1.3 engine id imagine??

[Stuart]

imho its got to be better to get a MLS gasket made up with the spacer built in.... any half decent engine builder should be able to do this (or contact steveboyslim on mig/vauxsport, he can guide you better)

since staking a gasket/spacer/gasket can allow mis alignment when torqing up etc.... I simply wouldnt trust that setup. One fire ring is more than enough :D Although I guess you could have the block, spacer plate and head ringed to hold the gaskets better.

[mowgli]

If I understand right, you want to turbo a 1.3

If so, then get some pistons from a mk1 astra 1.3 engine (not the s model)
the engine was produced to run at 2 hp levels.
1.3 60hp 8.2:1 cr
1.3s 75hp 9.2:1 cr

The dish is bigger. to lower the compression level for low quality fuels.

I did once get some 1.2 pistons machined down to lower the cr to make a 1.4 back in the olden days when gm only made them up to 1.3

[beavy69]

So for the combined thickness of the 2nd gasket and spacer:

Area of piston top face: 3.1416 X 10 mm (radius of 1.3 piston) squared = 314.16 mm squared

Increase required: 300 cc = 3000 mm cubed

3000 / 314.16 = 9.549mm (4 sf)

Is that correct? Any ideas?

[beavy69]

Obviously I need lower compression for the turbo but how do I know what cr i need? And if I were to fit the 1.3 astra pistons the head would be different meaning the cr would not neccessarily be the same?

This is why I thought if I space the 1.3 to make it a 1.6 it would have the same cr as a 1.6 for which the mvaux turbo kit is designed, or would the cr still not be the same as I am aware that that is the crucial factor over the amount of CCs?

[Stuart]

why would the haad be different if using the astra pistons???

CR is the important number yes. have a mince about on my sig site with the new and improved compression ratio bit

[Adam]

Fit a 1600 mpi head, that should drop compression a fair wack

[Stuart]

yeah but then his 1.3 injection system wont "fit".... granted it can be sold on since its rare as rocking horse poo.

[craig green]

But they dont sell as such;

I'd just whack in a 2mm laser cut spacer & try it. (between 2 head gaskets). Although its a rough way of doing it, any det will pop the gaskets which is safer than holeing pistons.

Find a laser cutting specialist in Yellow pages (Yell.com) I've used laser profiles in the past, they usually have a minimum order qty & you should get a handfull of spacers for ?30 or so.

[Adam]

yeah but then his 1.3 injection system wont "fit".... granted it can be sold on since its rare as rocking horse poo.
Sell the 1300 stuff, and use standard 1600 system.

[craig green]

Do it ona 1600 anyway. That will be the best result for a smallblock.

2.0 8v even better.

[mowgli]

there is another good reason for the piston swap... the cambelt stuff will fit easier. With a spacer you may need a new, longer belt, also the old piston rings won't seal very well.

[craig green]

The cam belt wont be any shorter, or rather wont have any 'wont reach' issues, how ever the cam timing will suffer by half a tooth or so, so you really need a vernier to get that back on. Head bolts etc will all reach no worries.

I read ages ago about some Toyota pistons that someone used on a 1600SE that dropped the compression nicely for 200 plus bhp.

[mowgli]

I read ages ago about some Toyota pistons that someone used on a 1600SE that dropped the compression nicely for 200 plus bhp.

Look in any good piston catalogue & there is a 1600 gm piston that is a direct fit for a gte/gsi & it comes at 8.2:1 cr. It is an option for countries with low grade fuel.

[Stuart]

the rings wont be damaged at all either, as the pistons will stop at the same point as without the spacer.... its if you stroked it that it would be an issue.

just spacers properly lash up squish and give utter toss burn compared to dropping the CR with pistons, meaning a small drop of power by comparrison

[mowgli]

the rings wont be damaged at all either, as the pistons will stop at the same point as without the spacer.... its if you stroked it that it would be an issue.

just spacers properly lash up squish and give utter toss burn compared to dropping the CR with pistons, meaning a small drop of power by comparrison

My point about the rings is more to do with trying to turbo an engine which to be polite, will have done 100k. the piston ring seal/wear will be quite high, loss of compression & breathing will be very high. for turboing an engine, a bottom end rebuild is a must, & from an engineering point of view, fitting low comp pistons has got to be the best way of doing it.

[Stuart]

well yeah there is that too :D

[beavy69]

So I could get some new astra pistons and the compression ratio would drop, but will it be by the amount I need do you know mowgli? Im looking for about 8:5:1 for a turbo is that right?

Am I looking for an exact figure or will the amount that they lower it by be "good enough"?

If I can definatly use them that would make sense hassle wise plus I could app some ARP bolts at the same time.

[Stuart]

CR depends on where in the rev range youre going to be sticking the boost in at..... if its going to add boost "after" peak torque of the N/A version (lets say for eample you currently make peak torque at 2500rpm) then you dont need to lower the Cr so much as the dynamic CR drops off after peak torque.

if you are putting it in early with a fast spooling turbo then you will need to either drop the boost or drop the cr a bit more.

Most turbo builds thesedays tend to be around 8-10:1.... so any milde drop is good.

have you worked out youre current CR? (dont go by the book number lol)

[beavy69]

Well peak power atm is at 4500-5000 rpm but thats with a kent AST2 but apparently I should use the OEM cam for turbo?

I wouldnt have thought there would be that much lag with a T2 on a 1.3/4 but I've very little experiance with engine managment and was just going to use the "special AMRP" (or whatever it is) that mvaux supply so not really sure when boost would come in??

[Adam]

Yeah, standard cam, if on a budget.
Or a custom grind suitable for a turbo.

You want to reduce overlap if using forced injection, a ast2 has quite a bit of overlap, so is no ideal and will loose power over a standard cam in your situation.

T2 should be ideal.
The dual rate regulator works by increasing fuel pressure under boost(it has a vacuum line attached to it)
Then when not on boost the standard management will fuel it.

[beavy69]

AAAAAARHH! WHERE HAS THE MVAUX WEBSITE GONE :(

What about blagging the pistons from my 1.2 - I believe that makes it a 1.4/5??

[Stuart]

an overbore will increase the CR...unless the pistons have the CR dropped.

[beavy69]

oh yeah course, bigger volume but same squish

[Stuart]

;)

[scottc1088]

iv got a spacer plate for a 1.6 if its any good. its 1.5mm iirc

[novacraig]

i no mate i want to know where the mvaux website gone

[beavy69]

Im not sure about the piston sizes scott for fitment of a 1.6 spacer, any ideas anyone? How much would you want for it posted?

novacraig, im hoping its just site repairs as opposed to something gastly and horrible like bankruptsy lol

[novacraig]

beavy69 i no i mate because i am thinking about turboing a gsi or a gte lump i dunno yet but it is like i am goin to run low compression piston so i can hopefully run more bhp threw the engine. my aim is to run about 220bhp i no it will be hard but fun

[beavy69]

might want to look at a t25 for yourself then rather than the standard t2

[scottc1088]

make me a offer if interested in the plate

[novacraig]

i no mate i was looking at gettin a t25 hybrid turbo if so but if i get the kit then just sell the turbo they give me init or just get part of the kit. has anyone heard anything about why we cant get on to mvaux

[Stuart]

get on the garret site and look at compressor maps (and read about them on vauxsport... ie how to use a compressor map)

oh and stop fcuking text typing (KNOW rather than no etc)

[novacraig]

sorry about that stuart and what kind of set up would i need to run that kind of bhp because i no you are very good with car and what is best for them

[Stuart]

try searching for turbo.. see what gets thrown up in terms of 1600 etc.

rather than hijacking this thread (oh and pelase no need for a new thread about 1.6 turbos lol)

[novacraig]

no i aint hijacking the thread well i thought people like you could just help out but hay i thought wrong and i was i am sorry beavy69 if i did hijack thread but i thought why it was up i would ask

[Stuart]

talk about take it totally the wrong way....... there are several threads that cover lots of peoples opinions/suggestions for a turbo build, you just need to look for them


http://www.pngclub.com/forum/search.php?searchid=228255

as an exmaple of lots of threads (look for the ones in mechanical.. mainly. but the SR build by green someone or other is good too)