Am I the only one...

[Sigmaproject]

Am I the only one still running the old carby turbo setup ?? I cannot remember the last time someone even mentioned the factory turbo setup. I guess that guys that have restored factory turbo sedans have gone to ground ..and only surface for a cruise or a Sunday drive. I use my as my daily driver and it is still running like a well oiled machine ( touch wood)

[Scorpma82]

Yeah not too sure why people dont have this setup all that much anymore.....I'm guessing it's just old technology being replaced by a more effecient setup.

Kinda like replacing your DVD player with a Blu-Ray player really.....

I'm guessing us guys (since the parts are so plentiful, common and cheap) just prefer to go the whole hog and wire up the EFI with it i'm guessing.


None the less, it's great to see your car and (more specifically) turbo setup still going strong and used the way the factory had intended on

[Sigmaproject]

Of course you are right. I have EFI in the pipeline..but only if I am forced to if I every get knocked back for rego (hasnt happened yet)
Just loved the challenge of getting the profile of the needle spot on. Carby's are great fun to fiddle with.

[geezer101]

The GH Sigma turbo set up is solid. Guys don't understand the CD175 carby and think that it's junk or something but they work brilliantly with this draw through turbo set up. And they are capable of making sooo much more power if you know what you're doing with it. The factory carby can support over 20 psi boost when you get it right without fear of destroying something. There aren't a lot of GH turbo's around as they've been either killed or junked for parts, but there are still some really good examples left.

[Sigmaproject]

Spot on..The needle can be profiled for whatever you want to do. I was running 18lb at one stage and the thing would actual scream out to 6500rpm in third. I soon got over that, because I could just see the motor..gearbox..or diff letting go and leaving me stranded in the middle of nowhere..Lol Now I am back to stock boost and a nice conservative needle that gives good economy, but still fun to drive.
You would not believe the stock of spare parts I bought about 10 years ago so I would have spares to fix things that wear out or break. I have not needed any of them.

[MadMuz]

The only thing that could be perceived as 'wrong' with the old style draw thru turbo, is that the turbo is pressurising a perfect concoction of air and fuel, which gets more flammable/volatile as the pressure builds, this is why a waste gate that dumps into the exhaust beyond the turbo (down stream) so if the engine backfires and ignites the incoming charge in the manifold, the resulting explosion has somewhere to go, rather than blowing the manifold (usually rubber connection) off the engine. I prefer draw thru to blow thru, as with blow thru, any leaks in the carby gaskets or butterfly shaft bushes can result in an under bonnet fire.... any pressure will find weaknesses in carby design or faults.

Draw thru is great. not as efficient as efi.... and the biggest bummer is you don't get the ffttt-fffttt-ffttttt when you back off

[Sigmaproject]

Having the fuel/air mixture compressed by a hot turbo compressor does seem to be playing with fire..but it works quite well.
No intercoolers or blow off valve allowed..but that is part of the stealth appeal

[Turbo047]

No Sigmaproject you are not the only one.

I'm still running the standard'ish draw through set up on my 81 Turbo. Just fine tuning after an engine rebuild at the moment. I've just fitted some flat top pistons (only because I ordered dished from the US and they gave me flats) but it was a good thing cause it's never gone better as a driver. Before it was ALL or NOTHING. Now it's quite good off boost, and still goes like a rocket. I had an issue with fuel starvation when I was running an electric fuel pump but I've change back to a mechanical pump and it's all good.

I've notice you are running ALOT of crankcase ventilation. Where you having any problems there. My Turbo is pretty old and it's a little smoky until it heats up.

If I could remember how to attach a photo I would.

[Sigmaproject]

Thats great to hear. Keep the draw thru flag flying. I had a fuel pressure problem as well with my electric fuel pump. But mine was too much pressure.

The crankcase ventilation..now that another story. When I first had the motor rebuilt to take the turbo, I removed the oil filler cap one day and though it had a bit too much crank pressure. I told the engine builder about it..and he said rip the engine out and I will have a look. So I did. Then he rang me and said there is nothing wrong with it..put it back in. So I did. Then he said if I was worried about it put another vent from the rocker cover to the air filter housing..so I did.

Runs great..good on fuel (I had a A/F ratio gauge on the dash for a couple of months until I got the carby needle profiled to give all of the right readings)

[Turbo047]

I'm going to try to add a photo of my engine bay.

[URL=http://s1156.photobucket.com/user/ ... .jpg[/img]/url]

Looks like it may have worked.

That photo was a little while ago. It now has a factory air cleaner, turbo blanket and a VT commonwhore master cylinder. I'll take another photo soon

[Sigmaproject]

That looks so neat. When I look at my engine bay I wonder where I went wrong

Is that a Magna dizzy you have installed..without vacuum advance connected ?

[tubby]

or one off a gn

[Turbo047]

Tubby nice pick up!

Yes it is a GN Dissy. I'm running a MSD 6 BTM. Just like a 6A but with boost retard. Best thing the engine ever got. It took a while to work out that it runs like shit with ANY mechanical OR vacuum advance. But after I locked the mechanical and disconnected the vacuum advance she runs great. The MSD gives you a dial in the cab that lets you dial from 3 to 0 degrees of retard per pound of boost. So if I can't get 98 octane I can just dial in more retard. It works really well. Base advance without any mechanical or vacuum is 35 BTDC. It doesn't like any less than that.

[Sigmaproject]

I sent my stock dizzy to some place in Victoria to be re-graphed and the boost retard canister fitted. When it came back the instructions with it said to set it at 10 btdc. (factory is 20btdc) I fiddled with it for a while and for me the best idle and and general performance with 15lb boost was around 15 btdc. Now that I am back to stock boost I could probably give it a bit more advance..but if it aint broke -dont fix it.

That dizzy canister is different to my GN canister. My December 1985 model was one of the last leaded petrol models made. With the introduction of unleaded and catalytic converters must have came the duel diaphragm dizzy.

[Sigmaproject]

Tubby nice pick up!

Yes it is a GN Dissy. I'm running a MSD 6 BTM. Just like a 6A but with boost retard. Best thing the engine ever got. It took a while to work out that it runs like shit with ANY mechanical OR vacuum advance. But after I locked the mechanical and disconnected the vacuum advance she runs great. The MSD gives you a dial in the cab that lets you dial from 3 to 0 degrees of retard per pound of boost. So if I can't get 98 octane I can just dial in more retard. It works really well. Base advance without any mechanical or vacuum is 35 BTDC. It doesn't like any less than that.

I bought a MSD 6 BTM about 5 years ago and could never get the car to run. The thing just would not fire up. I followed the instructions..and had dozens of attempts. But no go. I must still have it here somewhere..but who knows where.

[Sigmaproject]

Found it in the cupboard..The fact that I could not get something as simple as this to fire up is part of the reason I have not attempted an efi conversion.

[geezer101]

There has been a lot of counterfeit MSD gear popping up on the various internet vending sites. It's hard to spot the difference between the genuine article and the shite. Besides, neanderthal tech is easy to fault diagnose, easy to set up and easy to fix. Old school for the win!

[2Lgalant]

I'm going factory setup on my new gh can i use standard dizzy for now till I get another one re graphed?