dropping the compression ratio

[Rich]

c14se, will a c16se head raise or lower the compression? Unsure how i would go about working it out.

Best way of dropping the compression ratio cheaply via a spacer plate?

[comptoncj]

not 100% sure but i think the heads are almost identical and it wouldnt change the compression ratio, somebody correct me if im wrong but i dont think it would. :)

[AlexW]

It would up, slighty anyway iirc.

Lowering is what you would do to turbo somthing. Why? lol

[Rich]

mk3 astra with nice c14se engine for 20quid? lol :)

[Adam]

C16 head would drop the CR as they have deep chambers compared to C14s

[burgo]

would drop it quite significantly

[Rich]

Ideal if i wanted to run a turbo then? Would save spacer plates etc. I got the car today for 20quid, so decided to have a go putting a turbo on it as they can make quite good power and its cheap.

Thinking t25 turbo unless anyone would recommend otherwise? With a rising rate fuel reg and c20xe injectors. just the manifold i need to sort

Found a nova to put in possibly but its a sola so no roof :(

[Tomm]

You an drop your CR in may ways some are practical such as low comp pistons others are not so great like cut pistons and double head gaskets.

Either way once you have dropped your CR your internals are not going to cope with mega boost. I was running my civic with OEM internals at 10PSI relatively ok. i cant remember for sure but i think i was once told, If you are running a standard engine with standard internals you can increase the power by 50% before you hit ****. I don't know what the 1.4 power out put is? lets be kind and say 85bhp you would only in theory be able to take the engine up to about 125ish BHP before the thing shat itself. So you have to ask yourself is it worth all of the agro, sweat tears and arguments turboing the 1.4 when you could drop a N/A in there and get a great deal more power!

you then need to deal with the Oil feed and have your sump modified to take a oil return. Manifolds, injectors, charge coolers, management and so on, Its just a endless ball ache which is bound to go tits up at some point.

Even the best of the best 9k+ engine builds run into agro.

The T25 is a great turbo, i had one on my S13 and it was great, You also have the T28 from the S14 and S14A. The KKK turbos from Vag also turn out some impressive results.

I am sure you know your **** man but i have found unless you have uber deep pockets, loads of time patients and now a lot of people who know their Vauxhalls and their turbos its just a gigantic pain in the ****!

[Stuart]

it 100% depends on the engine as to waht the internals can cope with. Some manufacturers want such a long life from their engines in std form that they can take ooooodles of power (for less time of course).

1.6/1.4 8V low comp gm pistons are near impossible to come by :(

for some reason 38cc is sticking in my mind for the head volume of an early 1.6 8v head

[Rich]

Thanks for your post tomm appreciated. I bought a scrapper from work with a c14se in it for £20. The plan is to mess around with it until it dies pretty much lol Will probably end up seeing what it will take as standard if i dont find a cheap enough head. Not planning on running silly boost probably 10psi and see how that goes.

Thanks stuart will see what the 1400 is when i get the head off. Not that i know how to measure it yet

[Tomm]

no problem mate, i dont mean to come across as patronising at all or nothing. Its just ive been there, tried that an it usually goes tits up!

If the car has cost 20 buck then in my eyes it seems pointless spending 1K plus minimum on boosting it.

1K now may sound a bit OTT but belive me it does all add up, £150-£100 on a decent T25/8 £50 Turbo oil feed, £30 fabrication fees on the manifold, £250+ mapping fees,£100 decomp plate so on so on It does add up.

I mean if you wanted to do it on a mega budget you can run a double head gasket, which will cost like £20, bodge the oil feed and run a ****ty old T3 turbo off of a Derf or something with a uber **** Saab FMIC.

It just wont work very well at all haha! you can just raise the boost until it ****s itself but as i say i ran a safe 10Psi on OEM internals and a 1.3mm apexi HG.

If you want fun cheap and fat fun then try and get your hands on a TDi, Hybrid turbo and a map and you are laughing, a mate of mine as a TDi Leon, running a Hybrid turbo,map and injectors and he let me borrow it the other night, I was majorly impressed, Left a S2 ST for dead!

[burgo]

tomm you seem to be over paying a hell of alot imo. you can get a decent t3 easily for £100, or my mate managed to get a roller bearings t25 size turbo off a 2005 saab for a tenner from a scrappy. can do the oil feed properly for £20. fab fees!!!! what? do it yourself. wont need mapping if you just using fuel pressure to get the right afr's. frost motorsport will set that up for £100. wont need a de-comp plate if you use the 1600 head on the 1400 either.

[jimbob-mcgrew]

i'd say he was prety close on the money there, a new head and a complete turbo setup aint a cheap 5 min job.
not forgetting stuff like water pump, cambelt & tensioner, head bolts, oils, coolants and pipework etc. and like tomm said mapping fee's can be buck, u might find that you have to buy a programmable ecu in order to get it setup if yours cant be re-done. all adds up.
not all of us have our own welders and power tools etc for self fabrication either.

u sure u wanna do this to a 1.4 mate ? probably get much more bang for your buck switching to a 1.6/1.8/2.0 16v for the astra, and it'll be less of a headache too.

[Stuart]

u is text typing ;)

[Rich]

No offence but its not going to cost me anywhere near a grand lol

1600 head isnt going to be alot, i bought the donor car/engine for £20, already found a nova to put it in for £20. Budget is no more than £500

Water pump, old one will do. Cambelt is a few quid. Might buy some new headbolts if im feeling flush lol

Oil and coolant are free from work :p

Rising rate fuel pressure regulator will sort my fuelling out. Will probably get it looked at by a rolling road once its running to make sure its not going to melt but at the moment the plan is to just run it and see if it works.

[Dirtydog1]

1600 se head and managemnt (e16se) standard 1.6 bottom end, t25 turbo, 12 psi boost will give you a very lively little car! sod dropping the copression ratio, those engines are tough as old boots! i wouldnt waste your time with 1.4 though.

you just need to set the timing up so it doesnt pink on boost.

[Tomm]

fair enough, i didnt say it will cost you a grand, i said if you do it properly it will cost you that sort of money.

I wouldnt trust a £10 T3 as far as i could throw it!

[burgo]

well then you clearly have to much money. its not hard to see if a turbo is good or not. just check for how much play there is and look for signs of oil seal leakage. even if you pay £100 to have it rebuilt you basically got a new turbo for £110

[Tomm]

i see your point Burgo dont get me wrong, I am just nt sure how much faith i would put in a ten pound T3!

Would scare the **** outa me!

[Stuart]

to do it 100% properly its going to cost thousands, getting proper pistons made etc etc etc. but this is a budget laugh so meh

[Dirtydog1]

seriously mate, i built a hole engine for less than 500 and it still lives today!
bin the 1.4 get an e16se lump and management! job done.

if you buy a cheap turbo and it blows up, take it off and get a new one......simple. no need to get scared of it. lol