ATMO to Turbo

Hi all,

I'm pretty much new to these forums having finally taken the plunge with GTA ownership, lots of questions and need many answers.

Some of the EX 5 GT owners will probably remember me from the RTOC, owned the 11K mile 5 GT Turbo, which I sold a year and a half a go.

I've just bought an '88 ATMO which is in fantastic condition, ideally I would have preferred a turbo and went to look at a few, but unfortunately I couldn't find one in the condition I wanted, so I've settled for the ATMO and would ike to make this go like the clappers.

I would really like to rid the engine bay of the odd fire engine and install an even fire turbo motor, the problem seems to be finding a Z7U in the first place!

Is the R25 Turbo engine identical to the GTA Turbo engine in every way?, are the inlet and exhaust manifolds the same?

Do you know if the ports on the Z7X engine will allow the GTA's exhaust and inlet manifolds to bolt up without modification?

Thanks chaps

Check out the engine section under tuning and styling before you go any further. Steve's put together a list of possibilities all of which have been tried or are under development -

2.5 turbo.
2.5 twin turbo.
12v 3 litre.
12v 3 litre turbo (A610 engine)
24v 3 litre.
4 cyl (21 turbo) 2 litre.

Both the 3 litre options have been looked at for supercharging too. Steve can tell you more.

Dave G is assembling a 2.5 twin turbo and 21 turbo engine car and also has the ex PeterG 2.5 turbo with standalone ECU. Tony runs a large turbo, standalone and chargecooler on his A610 (ish) engined GTA and AlpineRob has a 12v normally asp 3litre that's almost finished. In between you've all sorts of variations on the standard turbo engine that people have made.

How deep are your pockets and what exactly are you looking for and why?

Thanks for the reply mate!

I'm not looking for silly BHP figures, just a nice reponsive car with a good useable power band and enough shove in the back to keep me interested everytime I drive it. The ATMO goes OK, but I must confess to being a bit of a turbo junkie.

My last ride was a 3SGTE powered MK1 MR2 with 260BHP, so I'm pretty well accustomed to quick motors.

We're talking about a long term project here, but I would like to set the right foundations for everything else to follow. That's why I liked the idea of running a low pressure turbo set up on the Z7X.

I always say this but I do like atmos, and they can go a fair bit quicker for hardly any money. In comparison, even a boosted turbo will have trouble holding onto an atmo unless you are at speeds over 100mph, and not heat soaked by then...

BTW, Z7X cant use the Z7U inlet manifold, has to use a 610 manifold if you want to keep the turbo at the back of the engine.

As you say mate, it is a fun car that can be driven quickly down a nice B Road, but it's just lacking in the shove in the back "Torque" department that makes a turbo set up so addictive.

I think the problem is that once you've been spoiled by turbo power nothing else will give the same buzz! Unless we're talking chevrolet LS series V8's of course

Just got back from a 12 month stint in OZ, and was fortunate enough to have a drive in an LS2 engined Monaro...Plenty of poke, and what a noise!! Gotta love aussie muscle cars!

Just throw in a Z7U then, far easier, spec the right turbo, chargecooler, ecu and injectors, and exhaust and you'll have all the punch you need. Ive just sold two good complete Z7U lumps, though if circumstances change the better one of the two may be up for sale again...

BTW, Z7X cant use the Z7U inlet manifold, has to use a 610 manifold if you want to keep the turbo at the back of the engine.

Thanks David, I suppose A610 manioflds on the open market are like hens teeth?

So in theory could you mix and match heads with bottom ends? Z7U heads with Z7X bottom end to allow the use of Z7U manifolds?

Or in your opinion is it easier just to swap a Z7U from an R25 and do the usual tuning mods?

Beat me to it mate!

Let me know if circumstances change RE: the motor

BTW, Z7X cant use the Z7U inlet manifold, has to use a 610 manifold if you want to keep the turbo at the back of the engine.

Thanks David, I suppose A610 manioflds on the open market are like hens teeth?

So in theory could you mix and match heads with bottom ends? Z7U heads with Z7X bottom end to allow the use of Z7U manifolds?

Or in your opinion is it easier just to swap a Z7U from an R25 and do the usual tuning mods?

Look at my post above..

You 'could' mix and match, but custom gaskets would be required, , the Z7U heads and cams aren't very good for flow (hence you need a lot of boost - which you don't want to do as its raised compression), so yes, start with a Z7U for less hassle and spend the money and time on the parts that matter,

TURBO,

just because I have one and it's great in my mind.
In standard trim, my Gtech accelerometer reported a 0-60 time of 6.18 which is pretty good for a 20 year old car. Since then it has had the boost derestricted, charge cooler fitted and a free flow exhaust fitted. Must be well under 6 seonds by now, but will be verified some time soon.

I think the problem is that once you've been spoiled by turbo power nothing else will give the same buzz!

I think you might be very surprised if you went out in a truly sorted Atmo. I had the pleasure to go out in AlpineRob's before he blew it up and it was a rip snorting ride which dyno'd at 160 at the wheels. He was running triple webers and a free-flow exhaust. (And its failure was not the fault of engine or driver).

Don't get me wrong - I'm in your camp - love a nice turbo motor and am building one for my DeLorean, but at the same time, I prefer the sound and feel of the odd fires. They have a lower engine note and a more instant, responsive grunt than even the NA 3 litre even fires (and I've owned several 12v's and a good condition 24v).

The work involved in converting Rob's to EFI turned up a few annoyances, so I reckon going turbo on the same car would be a lot harder and more expensive than just buying a GTA turbo to start with.

Have a play with what you've got, and test drive a turbo before making up your mind. I think you'll be surprised.

[BIG_MVS]

TURBO - They are far more fun to drive.

If I was using one every day though I would probably go for the ATMO. I have had both and although the ATMO was not running spot on, it just never had that kick in the back that a Turbo car gives you.

Surprised you didn't find a decent Turbo as there are a few in the classifieds section on the website.....

Atmo ...............As a daily driver

Yep, definitely some nice turbo's out there, and I believe I've viewed and test driven the best of the bunch. Went to look at one yesterday in black with 50K on the clock, which was in OK condition...Not as good as I was expecting for the money. Went to look at a blue one with 90K on the clock last week, which was again in good nick, but really looked it's age.

The ATMO i'm buying has done 32K and is mint...It's the only way I can describe it...The interior is seriously like new, if ever there was a timewarp ATMO this is it!

And as I said to my Dad, it's easy to make a car go fast...Just takes money and a bit of know how, but to restore a car to this level of condition would be a nigh on impossible task, mainly due to the fact that most of the parts needed simply will not be available at any price.

OK, there's always the argument that if it's that mint then it should be left original, but sod the purists! It's mint becuase that's the way I like my cars...I also like them to go like the proverbial off a shovel, so a performance hike is inevitable!