Hi All,

This may seem odd but there is a fellow who mounted the AJ27 supercharger system to his BMW 540i by way of custom made brackets. I have been on this site for days and researching a lot. I have no hands on experience with superchargers and jags but I am thinking to run the supercharger set up on my 540i. I know there is a clear improvement with the gen 5 blower in the 4.2 jags but is there any advantage to using the rest of the system such as intercoolers etc. Basically, the BMW set up uses the jags injectors and full supercharger set up including intercoolers. After reading Adam's 4.0 to 4.2 swap I read about all the differences between the heads and the intercoolers being mounted 7mm further back but I couldn't see any images to see where the physical differences were. Given I would need to piece all the parts for my bmw I was thinking the cheapest and easiest way is to just get the full 4.2 supercharger assembly off a wrecked car to reap the advantages of the updated blower but the adapter kit that has been made is for the 4.0 set up so I don't want to mess about with that. Ideally if I could get a gen 5 supercharger and the rest of the bits from the 4.0 set up it would be best. So, just wondering if those with experience in the differences can tell me what i'm in for. attached are pics of the bmw set up.

 

The basic idea is you want cool charge (air+fuel) in the cylinders and lots of it. The SC does the last bit but makes it hot. The ICs are to get heat out.

(Many cars, such as my STR, then have a 2nd IAT to let the PCM know the outcome and thus how to tweak timing.)

I'm surprised the BMW is happy being modded like that but if it is then great. I guess (!) it does not have an IAT2 which may mean it gets the timing somewhat wrong. Also, you're upping the compression when the SC is active. Don't be shocked if the engine is damaged.

 

In sort the difference is that the port locations are different on the heads, so the 4.2 intercooler runners would not line up with the adapters made for a 4.0.

However, if your interest in the 4.2 is only because of the Gen 5 Eaton, those are physically the same and can be interchanged between a 4.0 and 4.2. In theory you could source a supercharger from a 4.2 and everything else from a 4.0.

 

thank you. this is exactly what i wanted to confirm about the brackets. I was also searching and didn't find any info on why the whole intercooler and intake manifold changed on the 4.2 engine. I know there was some tech that was flawed and didn't make it into production that caused the differences in the head etc but I haven't found anything on the merits of the rest of the updated system. Would be nice to read something on that if anyone could point me in the right direction.

 

I have not seen a direct discussion about why things changed, but in the XJR 550 and Cam Spec threads there is some commentary by Count Iblis, who worked on the project.

They are rather long threads, but interesting if you have some time and want to learn about these engines.

 

The 4.0L and 4.2L heads have the same inlet ports spacing.
I am pretty sure the inlet ports on the 4.2 heads are offset farther back on the heads (7mm?) (I believe this is one of the reasons the Count indicated they messed up on the 4.2L head inlet port design. Comments Count?)
(See attached head images.)

I attached images of the older XK8 Supercharger assy and the newer STR.
The main difference is how the air is fed into the intercoolers. Back versus side.

As far as I know, no one has proven that the newer design flows better than the old design.

You could go with the older back fed design and as already stated, use a newer generation M112.

 

A little more details. 4.2 head inlet ports (RH head measured) sit 15mm farther back from the front of the engine block. As you can see in the last post the inlet ports are not centered to the valves. (4.0 head inlet ports appear to be centered, as well as Aston Martin heads.)

One other thing that may be different is the spacing of the intercooler outlet ports to the injector adapter manifolds. As you can see in the attached image, the head ports are all 98mm apart, but the intercooler ports are not spaced evenly. I don't have 4.0 intercoolers to be able to measure and compare to.

 

Cool project!

Is this for the E34 M60 4.0L or the E39 M62 4.4L ?

If it works on the M62 then I reckon the Range Rover guys would be very interested in this!

 

It's been said that the older design actually flows more but the newer design flows more equally among the runners.

 

Hello fellow enthusiast so I have the 4.0 supercharger setup on my m62tu 7 series I'm running really lean but I need the ANY AT ALL injector data say flow rate injector dead time is crucial thanks in advance

 

Do you mean the specifications for the AJ27 4.0 supercharged fuel injectors? If I recall correctly...., they are 360cc injectors at about 45 psi pressure differential. I have no information on dead time.