mk4 astra project

voszi · 23-11-2008, 11:10

hi everyone!

first of all, sorry for my so-bad english!

i'm from hungary. i have an astra mk4 gsi (honestly 'astra opc'), bought in 2005 from germany. i killed the engine in a year before, with installing some mods (stage-3 map + hws). shouldn't have done that.

so i started to rebuild my astra. i got some useful help from migweb in a past, and
i would like to get more help and advices from experts, because in hungary there are lots of mouth-experts, as my engine shows...

the astra is my everyday car, but i have a corsa vxr, and a frontera c20ne, so i won't go to the wall, if car should stand a month or so.

the specs of my car right now:

z20let block, re-bored to 86.50, and oil spray nozzles installed
z20let cylinderhead, with no modifications
z20let throttle body
z20let oil pump, with no modifications
wössner low comp pistons
steel rods
arp bolts everywhere
2*z20let headgasket
gema adjustable fuel pressure regulator
glyco bearings everywhere
balancer shaft deletion kit
470ccm bosch injectors
large FMIC with ss 2,5" pipework and end-up pipe connecting to the throttle body
walbro 255lph fuel pump
chris astley motorsport 5,8kg flywheel
sachs performance sintered clutch
quaife lsd for f23srt
vxr turbocharger
pre-cat pipe
3" exhaust system
large MAF
82 degrees thermostate
fuel pressure, oil pressure, oil temp, wbo2 (afr + lambda), egt, turbo boost pressure sensors
custom ecu program for motronic 1.5.5, 240+whp, and 220whp@4300rpm

voszi · 23-11-2008, 11:14

some pictures:

we made the fmic system:

**Lugy** · 23-11-2008, 11:18

Nice. That should be real fun when it's running

voszi · 23-11-2008, 11:22

the killed piston (no. 1 - not no. 3):

under the reconstruction:

so much things made my friend - c20let expert (as hungarian as can be)

voszi · 23-11-2008, 11:23

Quote:

Originally Posted by Lugy

Nice. That should be real fun when it's running

thanks!

it's running over 8 months, and i have made almost 25kmiles from this setup.

voszi · 23-11-2008, 11:27

i had no problems with the bottom-end things, but precat pipe doesn't like the heat:

and the f23srt syncro rings failed a bit:

voszi · 23-11-2008, 11:32

so i would like to change the system for the next level: 350whp the target.

i know it is so much, but i have seen cars here from this level.

i bought:

630ccm siemens injectors
VEMS standalone ecu, for full programming (VEMS hungarian brand, using in the USA for drag cars)
FSE power boost valve

and other small parts, for upgrading

voszi · 23-11-2008, 11:37

next step is a turbochager with manifolds. i would like to buy some bb charger.

so my question is, what would be the good choice for me?

an outer wastegated turbine like gt2876r
or an inner wastegated turbine like gt3071r

and can someone advice me a good manifold passed for the turbine and z20let?

i heard the nissan manifold (sr20det if i remember good), and i have seen some manifolds for gt2871r. can it be used for gt2876r? and for gt3071r?

regrads,
voszi

voszi · 24-11-2008, 07:59

yesterday i have read this forum and others for a day, to get more information of proper turbocharging of the zlet. so i made a plan for gt3071r-700382-3 model, which is with the modified gt30 turbine and t25 style turbine housing.

my k04 vxr turbocharger loads 1.5bar from 3000 rpm, and it is that we can produce 220bhp@4300rpm. so i want to keep this attribute as far as it can. gt3071r seems good for this purpose.

the plan:

- the maximum rev limit remains 7200 as now it is. i have balanced the system at a good named mechanic, but in hungary i don't think there are so good balancing systems and persons who can balance it well the crank and the others together. maybe if we have no problems, it will be lift to 7500 rpm.
- so at 7200rpm we should poke about 2bar (29psi) boost pressure, if we want to reach 450bhp.

i made some rpm points, added target boost pressures, and calculated the amount of mass air flow from the assumption of 150degF IAT & 94% VE. then calculated the maximum bhp from the assumption of 0.79lambda (11.6AFR) and a 0.53 BSFC. I think that assumptions are conservative enough.

so the result is the following:

2 bar slightly enough @7200rpm revmax. but the gt3071r turbocharger works every rpm range far away from surge line.

i think i should buy this one.

voszi · 25-11-2008, 19:14

today i have bought a new 350kPa MAP sensor, and have spoken with the dealer of s.p.a. vents, then i visited the exhaust-man

to thinking a bit about the new ss downpipe. he told me, 40mm bored pipes for a cylinder outlet will be enough for 450hp. i think it should be little bit larger...

voszi · 06-12-2008, 08:40

last week i bought 630mm siemens deca injectors. i have seen the partial ended downpipe. egr bunged. pics soon.

Corsa_shep · 06-12-2008, 14:59

Internal wastegate gt28r is best for your car I think

I am currently looking to do the same conversion on my MK4 so let me know if you find someone selling manifold at a decent price

voszi · 12-12-2008, 23:39

i make my own manifold. mk4 has a so small place in its front, and i think, it is better to make custom pipework to fit properly.

the nissan sr20det downpipe maybe good for you! here's a piece from ebay/USA, only for $300:

Product Info:

Item Title
NISSAN SILVIA SR20DET S14 S15 Exhaust Manifold

Application
NISSAN SR20DET PS13, S14, S15 Silvia

TYPE
4-2

Material
Stainless SUS304 / 2mm thickness

Pipe Diameter
42.7mm

Product Situation
Brand New

Net Weight
3.3 kg (genuine cast 6.8kg)

Warranty
One year / 20,000 km

you can buy a cheeper items for $150, but they aren't polished.

voszi · 04-01-2009, 11:59

it was a small accident in 23.12.08, a mum with a suzuki did not gave me my right of way, and my rear undercarriage deformated a bit (the body remains undamaged). must be change the whole undercarriage.

another bad news, that i wrecked the third f23srt synchro ring. (2nd gear, of course).

so i rearranged my plans, and started the definitve project of rebuilding.

i bought garrett gt3076r

and started the f23srt gearbox reconstruction for asynchronous system. in hungary there are three astra opc (naturally aspirated all of them) in the rally group "N", with this gearbox system.

***Andy_L*** · 05-01-2009, 16:07

English is good! Better than many on here

Project is very interesting

NexiaTurbo · 05-01-2009, 19:44

nice project, i have a daewoo nexia (opel kadett or astra mk2) and i get 300bhp with smal block 1.5L, so u can get 350bwp with your 2.0L engine easy!!!!!!!!!!!!!!!!!

voszi · 06-01-2009, 08:38

thank you! i would like to make the first hungarian 500bhp opel (vauxhall) astra.

there is a 'drag' daewoo nexia in hungary i know, it makes 12.98sec @ quartermile.