LPG Turbo and Other Questions

[GJTurbo]

Hi guys

So my project at the moment is a straight gas turbo 4G54, im just wondering if theres any people on here that have gone down this route and might be willing to share some tips? ill be using a late model magna head, flat tops (looking into 202 pistons), tr/s manifold with a gas research throttle body and twin b2 converters, (im not sure if i should have a single tank modified with dual lines or since ill be removing the fuel tank try fit an lpg tank under the car and one in the boot?) mabye try to find some stainless steel injectors and a high pressure water pump to use the injector bosses for water injection, or just tap threads in the bosses and use aquamist injectors, compression should be 9.2:1 and 20psi boost will be the starting point, ill be getting ARP head studs and im trying to find a supplier of copper head gaskets and bronze valve guides. does anybody know if those stainless steel oversize valves are still available?

For ignition im thinking an MSD DIS-4, but from what ive read i still need an ecu to run it to actually program an igniton map or it will just run whatever timing the dizzy is set to, so can anyone recommend me a good ignition only ecu that will let me run sequential ignition with 4 coils? also does anyone know wheres the best place to get a cam from? i do plan on ringing around a few places but it would be nice to have the rundown on what is available, and what the maximum you can regrind a stock cam is.

Turbo is a t70-to4z on a factory turbo manifold with a 25mm spacer and 2.5" straight through exhaust, i dont have a factory wastegate so im not sure if i want to make an adaptor to a 38mm tial style flange or block it off and weld a flange on the turbine housing, does anybody know of a wastegate available with a 75mm v-band flange? OR does anyone here know how to do the maths to calculate what psi that turbo would be pushing on a 4G54 at 7000rpm with no wastegate?

oh well id better get to bed, i hope you guys have some good ideas for me

[cheaterparts]

Hi guys
compression should be 9.2:1 and 20psi boost will be the starting point, ill be getting ARP head studs and im trying to find a supplier of copper head gaskets and bronze valve guides. does anybody know if those stainless steel oversize valves are still available?

For ignition im thinking an MSD DIS-4, but from what ive read i still need an ecu to run it to actually program an igniton map or it will just run whatever timing the dizzy is set to, so can anyone recommend me a good ignition only ecu that will let me run sequential ignition with 4 coils? also does anyone know wheres the best place to get a cam from? i do plan on ringing around a few places but it would be nice to have the rundown on what is available, and what the maximum you can regrind a stock cam is.

Piston height for 202 piston will be wrong for a 2.6 crank and will hit the head - they will stick about 4 -4.5 mm above the block at tdc

you would be smarter to just get a set of flat top pistons ether forged or good hyper pistons
copper head gasket try Ridgecreast engineering ( they have a web site so google them )
as for cams we had a 31/79 cam ground on a billet that worked quite good in a turbo app it was just a 35/75 grind that had the lobe centres moved from 110 deg to 114 deg - my cam guy has pilled the pin these days which is a pain but there are others out there again google may be your frend searching for cam gurus

[Billsy]

i Tig welded a 40mm pipe over the factory wastegate location and bolted a tial gate onto that.
and its easy to machine off at a later date

that lost the benefit of twin scroll as its a gap for the gasses to mix, but i wasnt running a twinscroll turbo either. so it didnt matter

[GJTurbo]

Piston height for 202 piston will be wrong for a 2.6 crank and will hit the head - they will stick about 4 -4.5 mm above the block at tdc

you would be smarter to just get a set of flat top pistons ether forged or good hyper pistons

i was thinking of using a 4G52 crank, then hopefully theyll sit flush with the block?. and 202 hypers seem to be cheaper and more readily available than astron pistons.

if im going to be reboring for the 202 pistons anyway do you have any experience with offset bores? im trying to find as much hidden power as i can. would it be possible to start with a 4g52 block and bore it out to 4g54 spec with the bores offset to the left 2mm or so?

[cheaterparts]

i was thinking of using a 4G52 crank, then hopefully theyll sit flush with the block?. and 202 hypers seem to be cheaper and more readily available than astron pistons.

if im going to be reboring for the 202 pistons anyway do you have any experience with offset bores? im trying to find as much hidden power as i can. would it be possible to start with a 4g52 block and bore it out to 4g54 spec with the bores offset to the left 2mm or so?

why go to a 4g52 crank unless you had to -- heres the first piece to find hidden horsepower -- a bigger motor makes more power
stay with the 2.6 crank
off set bore are you trying to unmask the inlet valve ? if so I wouldn't bother any gain you make would be off set by an unstable bore ( not enough meat in the bore for that )
you would prob find it easier to move the head across a bit but you would need to do a few runs on a flow bench to see if there were any gains
by moving the head on the bore

[GJTurbo]

yea i was always a firm believer in theres no replacement for displacement but ive heard that the 2.4 destroker makes more power over 7000rpm, and using the g54 rods you end up with a better rod ratio

my understanding on offsetting the bores is you get more leverage on the crank at the moment of ignition (ie: instead of the piston and rod being dead vertical above the crank relying on the inertia of the flywheel to pull it all around they are actually pushing the crank) but you raise an interesting point about uncovering the inlet valve, which is a good idea but abit futile seeing as i still havent been able to source any oversize valves.

oh well, im gunna go pour myself another scotch, someone better have some good ideas for me before i get back

[GJTurbo]

i suppose if i got custom forged pistons made up i could just have the gudgeon pins offset 2mm, which would have the same effect on rod angles as offsetting the bores

[cheaterparts]

ive heard that the 2.4 destroker makes more power over 7000

Why ?

my understanding on offsetting the bores is you get more leverage on the crank at the moment of ignition (ie: instead of the piston and rod being dead vertical above the crank relying on the inertia of the flywheel to pull it all around they are actually pushing the crank)

if it was the case why do you think that all engines are made with the bores on the centreline of the crank - are all engine engineers wrong

but you raise an interesting point about uncovering the inlet valve, which is a good idea but abit futile seeing as i still havent been able to source any oversize valves.

it's not uncommon in some engines to do this holden 6s it helped to get the valves more centrol in the bore - I dout there would be great gains in the hemi set up on the astron

what do you mean you haven't been able to source OS valves - where is the problem