thanks cambo , were looking forward to hearing all about it .
hope it all goes well for you . and therefore us too .

 

The tank is nearly complete ! just the right angle hose tails to weald on i wanted to dummy fit the tank and mount it first to make sure the pipes faced the right way . here is a link to some pics of the tank going in .

https://www.jaguarforums.com/forum/s...7/#post1532583

 

Just purchased a used throttle body off Ebay for $55 including shipping for my 2005 XJR.

Looks in as new condition. I have purchased a number of items on Ebay for my XJR that are listed as "best offer" and have generally put in a very low ball offer (1/3rd to 1/2 of asking price).. Almost 100% those offers are accepted and so far I have not been disappointed with the product.


Anyway to my main point here. Where is the best place to get it bored out? I see info on Maxbore are they the best game in town?

Pressed in my new rear SC needle bearings yesterday evening.

 

The throttle body I purchased will NOT fit MY 2005 XJR even tho MY was supposed to be compatible.

So now I have an excellent used TB for a 2006/7 XJR that I cannot use.

I have fully assembled my SC with the new rear needle bearings and when I take the original out will have my original TB bored out by Maxbore I think.

That will be in a while as I am going over the pond for several weeks soon.

 

Any chance you could post a pic of the one you bought in the slim chance it's compatible with the STR?

 

Three pics

 

Is the problem the bolt pattern or the plug?

You can convert the plug to suit the earlier TB wiring
The older one has the motor and position sensor on separate plugs
The newer one these these combined

Cheers
34by151

 

I have the earlier two plug version. Bolt pattern is the same.

 

Oops, well yes that throttle body you have is for a 2006MY onward engine.

Because there were a huge number of changes to the electronics and software for 2006MY, basically the whole car go an electronic overhaul.

I'm not aware of anyone who has tried changing the plugs on the connectors to get an old throttle onto a new one.

I can imagine the TPS ranges will be very different between the older and newer ones.

As you know these engine management systems are very sensitive to the TPS signals, you could try to be a pioneer but I don't think it's worth the bother, better off finding a correct throttle body.

I actually have a spare here but the TPS on it is no good, if you could find one of those new "aftermarket" TPS' then it might be of some use to you...

 

I agree with you Cambo.
I will simply have my original TB bored out when I swap my two super chargers.

 

I would think a bored throttle body will yield negligible power gains...

 

On its own or with a faster spinning SC and stage one air intake?

Several people on this forum swear by it.

I am not looking for top end gains more mid range.

 

Gotcha. Any threads on the TB? I think the key to all of the performance mods, hi flo cats 1.7 pulley, intake, TB, etc. for instance is getting a proper tune for your particular set of mods to maximize them, which is difficult with our cars...AFRs must be monitored. When you balance the AFRs with timing advance that's where your power throughout the powerband will be maximized...An example would be a properly tuned R on race fuel in bone stock form would more than likely out perform an R with the mods mentioned above with no tune...

 

Yes I suspect you are correct viper1996.

The TB info is scattered across multiple threads, just like a lot of information in this forum. A couple of people, in particular, who I will not mention because that would not be fair on my part.

Also other forums where there seems to be a lot more information however most without actual dyno before and after data.

Also when you look at the 2005 XJR intake system no matter what you do to increase airflow you still have the "bottle neck" with the inlet on the actual super charger itself which can only be "ported" slightly.

I would be seriously interested if an "ECU tune" became available.

 

i doubt very much that a bone stock 4.2sc in any of the R range on race fuel would be faster than or come close to being as quick as a free flow moded 4.2sc on say 95ron.
i use dinolishios APP to gauge hp . and every mod so far has shown up as an increase .
sure most of the mods helped only with mid range . but they all complement each other in the end . and defiantly add to peak hp, just not much
the caldoofy/quickets peplica alone was 9hp .
and remember these cars are self learning . no matter what we do to lean these things out it will end up around 14.7:1-15:1 AFR any way . so the more air you give it the more fuel it will give itself with in reason . and in turn more power this has already been proven by many with these cars.
i agree however max boring the TB is subjective. and can only change/help at WOT.
as it basically will think the throttle is slightly more open than it actually is at any thing less than WOT .
and it will continue to try running at 14.7:1 AFR there fore no gain until WOT is achieved. and thats only if the ecm will compensate for the added air flow .
and also as long as the heaton or the intake elbow is not the next bottle neck .

 

My 2 cents from everything I have read about TB porting on roots style superchargers like our Eaton, and from the comments of a forum member who did this mod on his pulley/exhaust/intake STR is that it has a negligible difference if any. For some reason, on TVS and TS systems, ported TBs with a bigger MAF give a good increase in power, but when the mod was done on an Eaton on exactly the same car it has made no difference. It's probable that this is because of the design of the inlet and the 90 degree bend at the TB which is the real bottleneck. If you look at avos' TS kit he's redesigned the whole intake to flow better. Imo a redesigned inlet with a ported TB would give nice gains on an Eaton.

 

Dont forget that the "self learning" is all controlled by a program/code. If you modify that code to act in a different way things will change. I am thinking about the very rich fuel mixture at higher revs as well as advancing the timing.

I have come to the conclusion that I will not modify my TB. I have already done porting myself to smooth out slight obstructions in the casting of the elbow etc.

 

Well I am going to chime in at this point, my x358 with my 80mm stage 1 intake, k+n filter, wot flap mod, full 2.5 inch exhaust with x pipe and 200 cell sport cats running royal purple xpr oil on 120,000 miles is running 462HP peaking at 650Nm torque. Rolling road print out below conducted on a dyno dynamics rolling road by a well respected tuning company Motor sport Developments in Blackpool, England.

 

Nice , that puts that thread to bed then . That's a very respectable number !
I'm intrigued though , you don't mention a pully upgrade ? Does it have one ?

 

No it doesn't!!!

Caldoofy has an X358...

The engine in his car has variable valve timing. His ECU is also the later version Pan-Pag Denso ECU which is the same one used on the XF SV8 and the X150 XKR.

The engine and engine management system in his car is already capable of much more power than the early AJ33S in our 2003-2005 XJR's and STR's.

The VVT is actually a major contributor to MORE POWER especially in the top end >5000rpm.

The early non-VVT cars had quite a compromise in the cam specs to reach emissons targets and driveability requirements i.e. a really fat mid-range with heaps of torque.

We have been looking into the cams as part of the bigger picture and it seems for the 2003-2005 cars they are the bottleneck, at least one of the major contributors.

Some testing on a later car by manipulating the VVT operation did prove this, by fixing the intake cam to the same timing spec as the non-VVT engine there was a considerable loss of power in the top end.

The plan at the moment is to make a test of retarding the intake cam on a non-VVT engine to a similar position of the VVT engine at higher rpm, and see if this is resulting in more power in the top end (what we expect).

However it's also expected that there would be a loss of torque in the low-mid range (not a great tragedy, there is plenty of low-end power, we can afford to lose a little) BUT it could also mean that the engine is harder to start with the intake cam in that position.

Hopefully there are some results to talk about in the coming weeks.

Have not forgotten about the tune either, but it seems that the tune itself is not enough to get around these mechanical restrictions of the engine, so it's probably a case of cams adjustment + tune to get some decent results.

The other option is to fit the VVT cams and VVT system but it's a big job and not really cost effective. Ditto for new cams (ala Aston Martin grind) so hopefully just this minor adjustment to the timing will do it.