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531 mods for currently NA auto

J

jjona5

Member
Joined
Nov 15, 2017
Location
Houston
What would you guys recommend for a currently NA auto 1990 240. I got a good deal on the 531 and plan on taking it to the machine shop. I might switch out the aw70 later on for a 350z six speed(waiting to hear some feedback) but as for now I'm not doing anything to the transmission. What do you recommend for the head gasket and final CC for the combustion chamber? Cam for now? I was thinking an A cam since it is still an Auto. I'm not looking for a race car, just a little more pep. I've read a lot about people increasing the valve size for the exhaust but that is more for turbo cars and I'm not quite ready for that yet, I want to find a big rod squirter block first.
 
A or B cam and a chipped ezk will help. That along with an exhaust is a good upgrade for more pep with an auto. An adjustable cam gear will help you tune the powerband a little. If you want to keep things minimal for now that should do it.
 
Simon has chips for ezk. sbabbs is his user. You can modify your ezk for the wasted spark and add the daughter board so you can chip it. Or find one with the daughter board so the only mod you would need is the wasted spark.
 
Don’t use a 531 on an auto equipped car with any of the factory camshafts. In an auto and with any factory camshaft, a 530 will be more efficient and produce more power/torque in a usable powerband than the 531.
 
hessam69 said:
KLR do you know why this is so?
Click to expand...

He is suggesting this because of the larger port size which would have slower air velocity and not be as efficient in the operating range of an automatic with a M cam for example. The power potential of the 531 is kind of wasted on a stockish engine.
 
I wonder why then my 1994 940GLE with B230FB (531 head and VX3 cam) came with an automatic, I guess that's why it has a 4.10:1 rear axle.

Also why the B234s have the same axle ratio.

The larger combustion chambers would also contribute. 9.3:1 VS 9.8:1 for the 530
 
hessam69 said:
I wonder why then my 1994 940GLE with B230FB (531 head and VX3 cam) came with an automatic, I guess that's why it has a 4.10:1 rear axle.

Also why the B234s have the same axle ratio.

The larger combustion chambers would also contribute. 9.3:1 VS 9.8:1 for the 530
Click to expand...

We never got that engine and driveline combo in the US. For sure it is more higher rpm oriented with the 4.10 rear axle. We did get the 16v automatics with the 4.10 though.

That B230FB probably has a better spark map in the ezk for higher rpm power. It made a big difference when I changed to a chipped ezk. Especially 3k rpms and up.
 
Didn't they come in autos overseas from the factory? Turns out I can get that modded ezk chip. I thought they came with A cams. That said I am piecing together my manual swap little by little.

Is this correct? 530=51.7cc 531=53.7cc I might just get the head shaved slightly or run a sightly thinner gasket.
 
I don't know for sure, but it's very possible they did. Increasing your compression always helps. A thinner headgasket is a must for better efficiency with higher compression at the same time. Shaving the head in addition could be even better depending on your camshaft choice.

My point is that putting a larger lift camshaft in the head will make better use of the flow benefits a 531 head provides.

If you race a stock 530 equipped car with an A/VX3 or similar stock camshaft in an automatic against a stock 531 equipped car with the same camshaft, the 530 equipped car will win due to better torque at low rpm.

Raising the compression helps improve torque, but doesn't get rid of the fact that the 531 has less port velocity at low rpm.
 
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