I often try to answer other people's questions on this forum, but now I would like to ask one of my own. Is there anyone who owns a manual 3.2L X300 and who has a scan tool capable of logging EMS paarmeters from the diagnostic connector. If so I would be very interested if they could measure the engine speed at which the engine speed fuel cut-off operates.

For one of my projects, I am trying to gauge the mamimum safe operating speed of the AJ16 valve train and it must be much higher thatn the fuel cut off speed of a 3.2L engine. The fuel cut off on my 4.0L AJ16 SC engine is set at 5,950rpm, but this value may well be higher on a 3.2L engine due to the shorter stroke of its crankshaft.

 

I cant answer your question Andy, but my 3.2 often revs 500 rpm into the red before it changes up (assuming accuracy of rev counter).
That is with your bracket and 98 octane fuel.

Does the AJ16 have valve overlap? I am wondering if the pistons will smash the valves if the timing chain failed...

 

I have 3.2 manual, running happily with one of your brackets, quite happy to help you out, but unfortunately I haven't got any sort of access to scanning tools... I know you've been speed testing your XJR at the Woodbridge airstrip, and Ipswich is just next to Woodbridge, but not sure how far it is for you!

 

Small world... Even though I live in NZ, my mother-in-law is in Suffolk and I know my way through Ipswich and Woodbridge, whether by A12 or BR

 

AL NZ,
Thanks for the feedback. I wouldn't trust the tacho for an accurate transient measurement. Also from your reply I infer that your car is an auto because you write "when it changes up. The gearbox is set up to change up before the engine hits the rev limiter. It might be possible to run this test if the J-gate was used to hold a lower gear.

Firecrow,
Thanks for the offer, but it was a very long drive for me to get to Woodbridge.

 

Mine's an auto, but I think it'll hit the limiter if held in gear... Anyone like to confirm for absolutely certain that the limiter will indeed operate in that situation, or pay for repairs if it doesn't?!

Silly question perhaps, but is the limiter set to operate differently in neutral?

 

I do know in XK's the limiter doesn't let you rev over 3000 ish rpm in neutral.

 

On the AJ16 engine the rev limiter works the same in neutral and in gear

 

My old 3.2 auto would shift past the redline depending on how the kickdown cable was adjusted. Using manual hold I once reved it to 6K by accident because I entered the chicane at Mallory wrong and missed the chance to shift up at the midpoint. It didn't hit the limiter.
My XJR auto with an electronic box will shift up at the redline even if say 2nd is manually selected and then drop back down as soon as the revs/roadspeed are low enough.
It might be best to ask some of the racers as the modified classes have significant mods which would support higher rpm / peak power.
The standard cams look quite mild. I guess for a high rpm engine you would need more lift, hence more valve acceleration and stronger springs acordingly?
I was at Oulton Park the other weekend watching some Astons racing. There was a DB7 with a Lysholme blower, steel crank, forged pistons and custom exhaust and intercooler. Owner claimed around 570HP, not sure of the rev limit of this build or the diferences in the Aston Head.
There is a nice silver/orange XJS in the race series with tripple webbers on a clean looking AJ16. I saw it beat all but one of the v12s in the top modified class and they make nearly 400HP so It must handle better have a good driver and a decent output, probably involving higher than standard revs.
Whats the plan Andy, sounds good.
John.

 

Hey, if I got myself a cable OBD2 USB for few quid from eBay, I would just need right software for it, am I thinking right? I mean I was planning on getting one anyway, because there are 4 cars in my closest family, 2 of which belong to me.
I've found this but not sure if it's any good, Jag is not listed...

Blue VAG OBD2 OBDII 409.1 KKL USB Cable Car Diagnostic Scanner Software Code UK | eBay

 

If you have an ipad iPhone or android phone you can get a Bluetooth connector and there are plenty of apps that will give all sorts of data including engine codes.

 

nope, I have pooberry... Sorry, I mean Blackberry... and doesn't look like I'll be upgrading any soon with all those car parts on order (not Jag this time)... That's why I'm asking if that sort of cable would be any good...

 

Hi John,
You asked - What was the plan?

I've taken a std AJ16 cylinder head and had larger valve seats cut into the std intake inserts. The throat of the inserts was also bored out in proportion to the increase in inner seat diameter. The inlet ports were then hand fettled and polished, with the guides pressed out. This process removed the mismatch between the cast shape of the inlet port and the machining of the throat which exists on the std cylinder head. The inner corner radius of the port was maximised to increase the flow coefficient. The exhaust ports were also hand fettled and polished. The std machining was retained on the exhuast seat because the thorat machining cleans up the cast surface of the port properly, unlike on the intake side.

I then designed some new larger diameter intake valves to match the new seat machining. The flow coefficients of both intake and exhaust ports were much imporved in flow bench testing performed before and after the modifications. Intake flow icreased by 15% at max std lift. To fully capitalise on these changes it would be desirable to tune the engine to produce peak power at a higher engine speed. This would result in longer period cams, which in turn would allow max lift to be increased. The resulting engine would be ideal well-suited to competition in the Jaguar race series.

Since the 3.2L engine has a shorter stroke than the 4.0L engine it was possible that the max engine speed was set higher than the 5,950rpm of the 4.0L supercharged engine. I can't rember now, as it was 19 years ago when I worked on these engines I think all AJ16 engines had the same cam profiles, just different timing , in the case of the supercharged version. If the 3.2L engine had a higher max engine speed this would indicate a safe upper speed limit in terms of valvetrain dynamcis for the std valvetrain.

You're right the cams are quite mild as they have 240deg periods, from top of ramps. This is because the engines wer tuned to produce high torque rather than peak power at high speeds, which would not be in keeping with the character of the cars.

Hope that you have found this info of interest.

 

Andy,
Sorry for not getting back to you sooner - I'll endeavour to remember to test it this evening on my way home!

A new upgraded head to your specs will be adequate payment...

Jon


Looks like it would do the job to me - but I don't know anything about the software you'd use with it on a Windows PC. I also have a cheap BT one & various android apps - that combo works well with my car.

 

Hi Ziggy,
Don't bother testing the engine speed limiter in your own car. In the end I took apart an old 3.2L Uk spec ECU that I had in stock for reprogramming. I removed the EPROMs and uploaded the data to my PC with an EPROM programmer. I then matched the addresses to another software levels for which I new the addresses of the engine speed fuel cut off. It turns out that the steady state engine speed fuel cut off on a 3.2L engine is actually 5,800rpm and the transient limit is 5,950rpm. So it isn't any higher than a 4.0L supercharged engine after all.

Well it wasn't the answer I was hoping for, but at least now I know the software address for the rev limiter in 3.2L UK spec ECUs that were built around wk35 in 1996.

Thanks to everyone who tried to help answer my question.

 

I am not sure but as a guess in standard form the valves would bounce before the bottom end gives up. Although I guess you don't want to risk the new head. The racing Aston had aftermarket rods, perhaps just a set of rods and bolts would be suficient on a short stroke. If the spec of the standard TWR Aston version could be found it could give a good starting point. I guess this engine is to be naturaly asperated, are you going racing?

 

Hi John,
Crankshaft torsional vibration was always the concern at high engine speeds with the 4.0L engine. These problems would initially maifest themselves as overheating and damage to the torsional vibration damper. The shorter stroke 3.2L crank was no doubt stiffer and therefore less inclined to suffer from torsional vibration problems. I'm sure it would be possibel to engineer lighter pistons and rods. This would in turn allow the counterweights on the crankshaft to be reduced and with it the inertia. This would increase its naturaly frequencey. However, these are all very expensive changes. I'm tryin to avoid the need for changes to the bottom end.

I have no plans personally to go racing. I'm just trying to make my cylinder head changes available to anyone else who might want to exploit the benefits for racng.

 

Andy, you're AJ16 GOD!!!

 

what kind of high speeds are we talking about and doesnt the damper take care of this problem?

 

The engine speed fuel cut off is set at 5,950rpm so the crankshaft torsional vibration damper only has to control torsional vibration up to this speed.