AstoN_B

iTrader: (1)

What's the recommended comp ratio for a 1.8 zetec running a t3 on emerald K3 ECU?

I found some pistons which will more or less fit the standard rods, and will lower comp ratio to around 9.0:1 without me having to spend £600

Is this low enough? or am i advised to go for a thicker headgasket too to shave a couple points off?

I know boost usually means lower CR but i know some people run 'high' CR with boost too, which is fine aslong as it's mapped well...

I'm aiming for around 180ish bhp and decent torques/off boost response.

I'll have 3 maps on the fly with the K3.

xr2wishy

iTrader: (2)

you'll be alright on high compression for around 200bhp, getting a 1.6 cvh to that on a non turbo engine only takes around 13psi of boost, my 1.8zvh takes 11psi to get to the same figure but more boost and less compression ratio (can't remember exactly).
use the thickest head gasket you can though. i reckon you'll get to 200bhp off less than 10psi of boost on a high comp 1.8 zetec.
why have three maps? you only need one as the map sensor should sort out fuel at varying boost levels.

tabetha

9:0.1 will be fine at that boost/power.
You don't need all three maps done, as ecu sorts out everything according to how it's driving, but DW charges same price anyway.
It has been useful for a few freinds who have afew track cars each, as it's just unplug from one car plug into another flick the switch, or just plug in resistor connector and job done, so saves a lot of cost.
Don't know where you are going for mapping, but if Emerald themselves all I can say is BOOK IT NOW, cancellation bookings are taking 6 weeks to get a spot!!
01953 889110, it will most likely be Leoni who answers so just ask about booking in and whether they have any cancellation, rare but do happen.
Don't forget to fill up with Shell V power on the way!!
tabetha

AstoN_B

iTrader: (1)

Thanks for the responses, appreciate it.

The use of three maps is primarily so i can play if im honest. The car is my toy, my project. I'd like first map as easy driving, low boost, smooth response, then map 2 to liven things up a bit. Max safe boost, over fuel a little on overrun for pops and noises etc. That kind of thing. All in the name of fun and smiles.

Map 3 i'll use to play with myself, so to speak. Try different things. Learn.

I recall the 1.8 blacktop runs 10.0:1 CR if im not mistaken?

Theoretically speaking, could i use a Bi-metal gasket from Ferriday Engineering in 1.0mm thickness to reduce CR to suitable amount with standard pistons? They quote that a decomp plate is fine to use even with only one headgasket but i'd rather use another route.

I can still find turbo pistons to suit without spending big money on a set. But little machining would be needed to fit Ford conrods.

I plan to have conrods shot peened for peace of mind.

AstoN_B

iTrader: (1)

I'll be running on Tesco 99 most of time, it's cheaper and must be 99Ron if it's named so.

V-Power round here is over priced tbh. If tesco isn't available, i'll use v-power.

However, i'm many months away from being on the road lol.

xr2wishy

iTrader: (2)

in all honesty forget three maps etc, just get one done properly and use an electronic boost controller instead.
a good map should be a 'safe' map anyway, you don't want it too 'safe' as you'll lose economy and power at the same time.
a good mapper will get it as good as it gets with one map.
i've got megasquirt and i'm only doing one map and if i change something, say cam, then i'll sort the map again. no point in switchable unless you plan to move the ecu from car to car.

AstoN_B

iTrader: (1)

like i said, it's my toy. The ecu i'm choosing comes with 3 map function, i'll be using them.

The idea of lower boost for normal driving appeals to me as it puts less stress on the whole engine and drivetrain, and makes for a more sensible relaxed drive. Then when i want, i can have aggresive boost building etc.

The difference is i can have it mapped to drive differently, depending on my mood. If i want half throttle to be half boost, i can, if i want half throttle to build full boost, i can.

It's just a switch away.

I've just done some workings out, if i use an 81mm piston, with a 1mm Bi-metal gasket like Ferriday's, it'll drop comp ratio to 9.2:1. Thats if the other pistons have the same deck height. I'll assume they'll be lower decked since they're from a production turbo car. So i should be ok with around 0.6mm gasket?

xr2wishy

iTrader: (2)

/\ well i disagree with the above, but it's your project.
you don't need to go lower compression, more power comes from higher compression, but puts more strain on the componants.
i don't really understand the last statement about the pistons should be the same, don't do calculations on erroneous information, get the componants and do proper tests.
and as for 'other' pistons, what pistons, where is the pin in relation to the piston and does is actually fit or does it need rod work to get it to fit, i.e. in the case of the XE pistons on zetec rods.
IMO 9.2:1 is a little high for a turbo and would not run more than say 7psi of boost, as i would imagine there would be loads of stress on the rods for sure, more compression means less margin for error on fueling and timing, which is why we all know we lower compression ratio.

AstoN_B

iTrader: (1)

If i'd won the lottery, i'd buy forged bits, but i dont want to spend more on the engine than i planned for the whole car. I can't warrant big money when not going for big power.

I've spoken to an engine builder who supplies new standard pistons for all cars and he's checked some diagrams.

He gave me a list of 12 engine numbers from which i can use the pistons. They are 81mm bore, and all have a 19mm pin.

He then gave me a list of 12 engine numbers where i can get 20mm pin pistons, identical to the ones above apart from pin size.

He told me that either would lower CR to aroun 9:1 but the 19mm pin would be easiest to fit, and stronger since i wouldn't need to machine the pin bigger in the rod. I can only be more sure once i've bought an engine and given him exact measurements he asks for.

If they drop it to 9.2:1 and with a thicker gasket at 1mm that drops it to 8.5:1

How much boost am i likely to run on a t3 at 8.5:1

Am i right in thinking to get a bigger exh housing to flow more at same boost?

AstoN_B

iTrader: (1)

I've read that zetec rods are ok for circa 250bhp if they're shot peened, which i intened to do if it's true. I thought it was the pistons which didn't allow for the boost, but if i used pistons from a standard production turbo car then they'd withstand similar boost to the car they came from/were designed for?

xr2wishy

iTrader: (2)

you don't need a bigger exhaust housing to run more boost, the standard t3 is ok for 12-14psi of boost, not great over that though.
a bigger exhaust housing can be used for more peak power, but at a sacrifice of spooling revs.
i'm a few miles from you and run a 1.8zvh (CR 8.0 IIRC), can't remember pistons though.
and i run a cossie 4wd turbo usign cossie housing and modified down pipe, running on megasquirt and at 10psi it's an animal, 14psi it's spinning t1-r's in third on a dieselling gears form a fiesta 1600, my engine builder built a few in the past and ran around 20psi in them, he doens't really do much these days as he's semi retired now.

xr2wishy

iTrader: (2)

in regard to rods, i've heard stories where they've been used at over 300bhp, it's revs that kill rods not so much the power.

Chip

iTrader: (3)

Yes, most rod failures are rpm related, although that doesnt mean that they cant fail from pressure too, but generally on road fuel you wont be able to generate enough cylinder pressure to break a rod on the power stroke.

AstoN_B

iTrader: (1)

Well i've got a T3 on it's way as we speak, ebay bargain, probs need a rebuild but being described as working order at £40 its 'under budget' lol.

I'll stick with 1.8 blacktop, and use the pistons i had in mind permitting they'll fit the rods without major headache. Then a nice thick gasket to drop to around 8.5:1 in total.

I'll not be running massive boost all time but i'll shot peen rods anyway. Minor headwork should keep flow going too.

Chip

iTrader: (3)

RST T3?
cossie one?
R21?
Metro T3?

Or other?


Very different turbos all with same name!

AstoN_B

iTrader: (1)

Lol good point, it's an Escort RST T3.

tabetha

Normally the fuel cut is enabled on the overun, but on your "play" map just disable it, so the injectors still fire, I have a 10mm hole in my lambda bung to let air in, and the bangs when hitting the hard cut 4500rpm are ace, the soft cut I set at 4200rpm.
I tapped a thread in the hole so that I can insert a bolt for the mot, ie so there's no leak to fail the car.
Best of luck with it anyway.
tabetha

AstoN_B

iTrader: (1)

what are those soft and hard cuts for? overrun? or like launch limiters?

I like the ideas though

It's all about fun.