I'm so in for 14-15 lbs on my system.

Cannot wait to see the upside of a better cam.

It's approximately multiplicative. Say your cam gives you a 20% boost in power, and your turbo 100%, the overall gain is roughly 140%.

Quote:

I reckon the stock inlet will hold you back on any gains from the cam - that's downright unnatural pressure differential!

I assume these figures are at the engine?

You might have to go into business on your 71 series boxes to A banger conversions mate! lol With the cost of A series 5spds, it might even be viable?

So I guess the original build thread is a bit out of date now. As you seem to be not doing this to sell a kit, can we assume that the final product will end up as a DIY build thread and everyone will be driving 120kw a12 turbos?
Any chance of you producing a manifold at least? Out of the whole build, this is probably the most difficult part.
A step by step thread on the final product (as per the original thread) would be very useful.
Thanks for the effort, I am sure everyone appreciates your time and effort here as much as I do.
JD

Harry, these figures are ATW(hubs) but without a gearbox. so its an engine test frame that bolts to a H165 diff via a tail shaft. Yeah, that inlet manifold wont helping things much with the big cam!

I put the 260@.050 cam in yesterday. I didn't do the springs as I wanted to run the cam in on the standard ones first.

I ran the engine at 2-3000 Rpm for about 20 mins to run the cam in before starting to push it.

I backed the gate back to 15Psi to start to get the fueling and timing where it needed to be. I had to remove fuel to 4K and ad fuel past 5500. This meant it must have been shifting more air past 5500Rpm. I set the rev limit to 6500. Encouraging signs..

Then went to 18Psi and bumped the rpm limit to 7200. timing at 24Deg, then 26, then 28. Power and torque increasing each time timing was added.
Unfortunately on the 28 deg, 18Psi run it lifted the head again and pushed a bit of water out of the radiator. I didn't try to do any more after that. I would have loved to get it back up to the 24Psi that I tested the old cam too, but looks like It will need studs for that(or at least retension the head!!lol).

Did some digging back through the logs to find an 18 PSI run at 28Deg with the old cam for comparison. Here are the differences.

STD cam, 176Nm at 5600(228Kpa) and 107Kw at 6300(222Kpa)

Big cam, 170Nm at 6300(222Kpa) and 120Kw at 7200(222Kpa), power still climbing set rpm limit.

I was hoping that it might come on earlier with the fresh intake charge being blown through into the exhaust manifold on overlap( a bit like antilag). This happened on the race car with this same cam but didn't on this engine. Could be the tuned manifolds or hotter exhaust being the difference.

If I was to make a recommendation based on the testing so far, It would be to use the standard cam and smaller turbo(R32-33) if building it for the street with these manifolds. The cost in later boost wouldn't be worth the extra power going to the larger R34 turbo on the street. The other advantage is you can use the smaller 880 cc injector located in the manifold, use unleaded and still make good power(around 80kw at 12Psi). This also allows intercooling.

I have been impressed at how much power the STD A12 head will make. I do think its good for 140+Kw with a cam and springs and the larger R34 BB turbo. I'd also recommend a new inlet manifold with four injectors pointing into cleaned up ports and head studs. Be good for someone that wanted to take it to the track etc, but would also need a gearbox upgrade.

You don't mess around! When you said big cam, you meant BIG cam! lol
Very interesting thread mate - great stuff!

Having played around with mild, low boost carby turbo A12s years ago, the basic setup's power is no surprise to me, but the bigger boost E85 numbers are mind boggling on a stock A12 small port head and that puny manifold! Unreal :)

JD, the build thread is all still relevant. I just put the big injector in front of the compressor when I switched to E85 to help with its vaporization. I wouldn't put the injector there normally. If someone wants to use E85 I would say that port injection would be necessary, or at least highly recommended.

Regarding the Exhaust manifolds, I could do them but on these conditions... I would only do them the same as what's on this engine and to suit a RHD 1200 with Skyline turbos(T28 flange w drilled holes as studs are in the turbine housing). I then know they will fit without modification to the crankcase breather pipe or inlet manifold. There is also good access for a dump pipe as the turbo sits at a 15 degree angle. The waste gate actuator mount will have to be modified by the end user. The cost would be $450. Plus shipping. No discounts for higher numbers.
I'm sorry if you think this is expensive, but they take a long time to make.

I'm not sure it they will fit other turbos, LHD or datto 1000's..



Harry, just read your comment. I'm blown away too. With the cost of oval port heads being $300+ and harder to find. Its great to see good power can be made without them. I might make a better inlet manifold to suit the A12 head to see if it helps much.

edited:
Ive always been a believer in the round port head especially the M30
and H10 heads which is what I remember as the better chambered round ports.
If the manifolding say something like the Rowland manifold can be made
to fit it will suit the ex. mani sykine has offered for 450 which is
a very reasonable price considering the quality and time.
This is definitely with a good box a real competitor to later engines.

Have you been able to determine if it will fit a 1200 Sedan/Coupe?

The early engines have more room after the motor mount. The newer engines have the mount 35 mm further back

Late 1200 block

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  19179 early A12 block.jpg (28.21 KB)

Thanks for the pics DD, yes it will fit the early blocks. I'm not sure about LHD though. I should be able to work that out with some careful measuring.