Have searched for about a week and am not seeing any conversation or interest in supercharging a naturally aspirated V8 in the X350 / X358 body, either on this site or across the web. If there are any conversations, will appreciate a pointer. Apologies in advance if I am simply not entering the correct search terms to find any existing threads.

Am here to learn and will appreciate insight on a SC conversion or whether there are too many things to touch which make the project highly complex. So far, available information is making this look like a straight-forward event providing I can get all the parts.

Reason for looking into supercharging the NA V8 is that I am currently shopping for a X350 and ability to add charge air will open up my search to include NA engines if this is workable. Yes, I get it that the XJR and a very few other variants have the SC which might make for better economic decisions, but their numbers are also small compared to what is commonly available for sale.

From what limited technical information I am seeing, cannot tell whether the NA and SC engines are different enough to prevent easy addition of a supercharger. The only mechanical variances I am finding via the web and here in the DIY / Maintenance section are different compression ratios and the NA engines were first to get variable valve timing where SC engines got it in 2006. Yes, there are a few other minor differences like crankcase venting, but that seems like small stuff.

The main diver for focusing on adding charged air is that I have learned enough about vehicle engineering to know that starting in the 1990's, engineering was integrated with the accountants to start streamlining parts to lower costs. Definitely not looking to insult any accountant or engineer, and at the same time it did have an impact on vehicle design. With that, it will not completely surprise me if the only real physical differences in the NA and SC engines are a thicker head gasket, possibly different fuel injectors, and maybe stiffer valve springs.



What am missing?

 

https://www.jaguarforums.com/forum/x...ersion-137951/

https://www.jaguarforums.com/forum/x...rger-xj8-8872/

From what I'm seeing in those, the engine (and i think the transmission as well) is substantially different; different heads (which probably gives the different compression ratio,) different electronics, yada yada yada. In all of those threads, the advice is to buy the supercharged car if you want on. It's not a bolt-on conversion at all.

 

Personally I wouldnt do it and I have done a lot of tuning, engine swaps etc
In the x350 the differences are a lot between the n/a and supercharged versions and the price difference between them dont add up to the coversion cost.
Of course you can supercharge the n/a motor, but when you can get an already supercharged version with stronger gearbox, bigger brakes from factory, why not start with that.
Instead of converting a n/a car you can concentrate on getting big numer out of the xjr/super v8 and the total cost will probably be lower.

 

Appreciate the quick responses.

The referenced threads do not directly help as they are for the the X351 and X308, respectively. Am guessing that the presumption is that this was discussed on other engines and dismissed. The conversations do answer the question of whether this was discussed though

QuattroFrank, goal is not to get even bigger numbers out of the supercharged engine, but rather to bring the NA V8 up to the SC level. Based on the statements, it is looking like the only real way add SC is an engine and transmission transplant. Things like brakes are wear items and time will help with making reasons to replace those parts to the SC variant.



Really wish that there was more commonly available and searchable technical detail available on these vehicles without having to get paid subscriptions to servicing systems. Even the wiki site is very thin on specifications which not surprisingly is showing that there are apparently significant gaps in information.

Thanks!

 

The X351 is minimally different from the X350. As far as supercharging, everything in there applies.

What it comes down to is that if you want a supercharged Jag, buy it that way.

 

It seems like you are willing to do research and get your hands greasy to get what you want. If you are patient you will inevitably find an SC in need of work, especially a head gasket replacement. You will find that they sell for quite cheap. Even if you don't want to take a risk on an engine with a blown head gasket (as these may have a warped deck to go along with it) you can, at least in the current environment, source an SC engine to swap into it for $2000 or less.

Right at this point in time, these cars get totalled or forsaken for the most minor damage or repair needs, making finding a good project car fairly easy. I don't think this will be the case in a few years, so you are getting in while there are still some good opportunities. I chose a car that was cosmetically, nearly perfect, but had a lot of little electrical and mechanical issues that collectively overwhelmed the PO, so he sold it to me for cheap. Deals are out there to be had, but you might want to consider expanding your search to find exactly what you want. For example, there is beautiful one in Detroit for $3000 (don't know about the corrosion) that needs a head gasket, there is a pretty nice one in Sacramento for ~$8000, and one in Phoenix for $7500 that is a worthy contender. This is just a snapshot from today, but you will find even better prices if you spend time doing research. Personally, if I get an SC, it will be a Super V8.

I agree with @quattrofrank and @wfooshee to get the SC from the start. There are too many differences between the cars. Doing the Brembo brake upgrade (which I will do, at some point) will typically start at $400 for the calipers and maybe even the rotors. You will then need the front knuckles and rear parking brakes (usually rarer and sometimes more expensive than the set of brakes). For me, I went with an NA version because I wanted the better fuel economy, but I definitely prefer all of the other aspects of the SC cars. For this reason, I even bypassed an XJR that was only $1500 more (with less miles) than what I paid for my NA, but I was quite tempted!

 

Nightmare times ten...

 

Please post back your progress as it will very interesting to the rest of us.
Any possible candidates yet?

Oh by the way. Accounts have run over Engineers since the beginning of time. They have to because the product has to made/sold at a profit or the company will go bankrupt regardless of the quality of the product. I take it you have never worked in a manufacturing environment as an Engineer or an Accountant?
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I'll answer this simply... forget it!

 

Ok, got-it that the conversion is more work than what the lack of commonly available information implies. Might help if there was a sticky to run-down the differences in the underlying components to help others in the future. Just a thought

Correct, do not mind getting involved in a renovation / repair project. Rather fun going about it that way as it gives a great opportunity to reverse engineer things. And in turn it makes future maintenance easier.


Am actually looking for ready-to run candidates. Do not mind paying over the blue-book numbers as long as the seller is able to justify the asking price. Seems that there are two varieties of cars in the marketplace at the moment with some at reasonable prices based on collision history, or people pricing their vehicle like it is the diamond on the heap. Sure, the SC is rare, but it is still a depreciating vehicle and not a Picasso. One ad I found was the diamond type where the seller is asking for a lot of money, yet the ad is 6 months old. Some people do not get-it that things like not knowing the transmission fluid or coolant change histories are probably worse for the vehicle's value than a repaired door.


I have actually worked in both environments. Know accountants better, and can keep-up with the engineers too. Accountants can come up with some bizarre logic at times as they tend to lose sight of the big picture and focus on the numbers. Once had a licensed CPA external auditor from one of the big houses (not some small local firm) ask me to prove an ending G/L balance of 0.00 when the starting balance was 0.00, additions were 0.00, and deletions were 0.00. That was an interesting conversation I also know, and have worked with, plenty of engineers whom are tired of having to develop it twice because they were not allowed to build it correctly the first time.