For the X-351 S/C have we decided on the best performance mods? I guess I'll dual mine out and add a smaller S/C pully and a tune, and I'm thinking about exhaust cut-outs as well.
Am I missing anything except maybe an exhaust crossover? I know there are a few companies who do tunes on our rides, but I'm outside of Houston and don't see any of our preferred vendors doing business here. I've thought about the email or mail order option but I'd sure like someone to put the car on the dyno and tweak the numbers in person. I could use ya'll help please.
Thanks,
Bill

 

Eurocharged in Houston can help you out. Btw...if you're going for big horsepower the exhaust needs to be a priority. The stock system is way too small and its the reason for that raspy sound you hear at higher RPM's. If you're shooting for 600HP+ the exhaust needs to step up to 3". I plan to build a custom 3" myself with 200 cell converters, X-pipe, and will open up the stock mufflers to increase the pipe size to 3". Plan to add cut-outs when I wanna get really nasty. I'm also going to use water/meth injection and bypass the stock PCV system. This engine is capable of handling 700HP+ with stock internals. The only big question mark will be how long the stock transmission can handle it before failing.

 

Awesome! Thanks for the information! 3" it is!!

Bill

 

What engine do you have?
I have an XJR with the 5.0 V-8. I am doing a lower pulley instead of the upper. Since you need smaller and smaller upper pulleys to get more boost you have less belt wrap and can slip easier.

With a lower pulley it has to be larger so you are increasing belt wrap and torque capacity.
But these DI engines really respond to a tune so that's your best value for sure.

I am adding a larger inter cooler and an up-rated IC pump. Still data logging so I can tell if I have gained anything.

No one has done the Meth injection so please post back how you plumbed it in and what gains you got.
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Thanks Clubairth1. I'll start my research.

 

If you plan to to go with water/meth there won't be a need to upgrade to a larger intercooler. The pump upgrade is a good idea either way. There's no "plumbing" to really deal with. Punch a hole right at the intake junction in front of the throttle body and thread in the injector. Mount the tank, pump and run the line to the injector. Punch a hole in the SC lid for a boost sensor and run the line to the controller. With water/meth gains are what you want them to be. If I want 30HP then I dial it in. If I want 100HP I dial it in. The other key factor is who writes the tune and how conservative or aggressive you want it to be with/without meth. I'm going to run two different meth maps. One for daily driving and one for the track.

On a side note...I discovered that the SC intercooler is tied into the engine cooling system. That is absolutely the dumbest thing Jag did to these cars. You're now forcing your SC cooling system temp to equal the engine cooling system temp and you're saturating the intake air charge with heat which we all know is a HUGE no no. Timing is being pulled just driving in normal traffic. I'm going to separate my system, just like GM, Ford and Dodge do, which will radically drop the SC and IAT1 temps. Only need to plug the outlet on the radiator and then I will run the intercooler top inlet to its own expansion tank. With that done the SC temps will tremendously drop and the water/meth will have a much greater affect.

 

What is your end goal for the car? How much HP do you plan to push it to?

 

It's my daily driver so 600 at the rear wheels is fine. Just need to spank the little punks in the Mustang GTs.

 

clubairth1 what are you using for data logging? What's the preferred logging app or method for Jags? This is my first Jag and I've decided to go ahead and get the SDD software and cable to make some programming changes but need to get a good data logger so I can verify tuning changes and monitor IAT's.

 

Be careful...there's an awful lot of really hot sleeper Mustangs out there. And their cars are a whole lot lighter than yours. But you'll definitely kill the stock GT's. With your HP goals you'll definitely need to go with a lower pulley upgrade as clubairth1 stated. Then use the upper pulley to fine tune depending on what the tuner needs to get you to the HP level you're looking for. Upgrade your intercooler pump like previously stated and separate the SC cooling system from the engine cooling system. That alone will gain some HP back just from the stock ECU not having to pull timing due to the intake air charge being much cooler. Upgrade your exhaust to a 3" system. Consider a water/meth or nitrous system.

 

The IC system is separate from the cooling system. They only share a common vent point. Very little fluid is exchanged between the systems. Only for filling and normal thermal expansion. That's why we have an IC pump. Without it no circulation in the IC system. The engine water pump does not circulate fluid in the IC at all.
Here is what Jaguar has in the shop manual.



This is the same setup as my 2005 S Type R had. The temperatures of the coolant is very different between the two systems. But as you sit in traffic it all gets hotter and hotter.
I am a bit unsure about installing the up-rated IC pump as after reading there is some question as to the need for it? You must let the coolant stay in the IC long enough for the heat transfer to occur. Pump too fast and your just circulating hot water. Again without doing some measurements we just don't know.

Data logging is recording some sensors as you drive so you can play them back to see what's actually going on. Right now I want to know if I am approaching heat soak. So I need to see what IAT (Inlet Air Temperatures) the car produces when under boost. Note be SURE and monitor the right sensor! All boosted cars will have at least 2. We want the one AFTER the SC. In most software this is labeled as IAT2. If the car is not going into heat soak then a larger IC and pump are wasted money. Or more importantly you can run more boost because you have not hit heat soak yet!!

Also I have only seen a max of 11.5 psi boost on my 2014 XJR. Jaguar claims 13-14 psi stock. So am I having a bypass problem or just not spinning the SC fast enough? Plus after the pulley install do I actually get any increase in boost? The car has a number of ways of reducing boost and power if we get outside it's comfort zone. But the car is so powerful and builds speed so fast I can only get a few seconds of full power before I am out of road! If I go back to the Texas mile I will record some runs. That's the only place I have ever been able to keep my foot on the floor for an extended time period.

The XJR has a pretty nice sound stock so I am leaving the exhaust alone. Not very big gains have been seen on other cars. Probably the 200 cell cats will give you the biggest increase.

Read the F-Type and XF forums as those guys are much more into mods. We have several F-Types running in the 10's which is pretty damn quick for a street car!
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Newtons 3rd law...for every action there's an equal and opposite reaction. Connecting the two systems will make them equalize. So the supercharger cooling system is running much hotter than it needs to and is saturating the SC with heat. That's why you don't see other systems on the market from other manufacturers doing this. Its also unnecessarily pressurizing the system. In the Ford, Dodge and GM communities we found out over a decade ago that the factory SC cooling pumps are moving waaaaaaayy too slow and actually saturating the SC with heat. I can post links to numerous different sites where data was collected and it was proven time and time again that upgraded coolant pumped tremendously dropped the temps. Weapon X is one that did massive amount of research and it was determined that we needed to upgrade the SC pump in our 2009 ZR1's from the factory 7gpm pump to a 55 gpm pump. The law of thermal dynamics tells us that we have to move the fluid faster or else we saturate the SC with heat. No it doesn't prohibit heat transfer and in fact does the opposite. There of course is the law of diminishing returns that you have to find out for each system.

I'm well aware of what data logging is and the dynamics of supercharged systems. I've built 5 FI cars/trucks making close to 1000hp and now my new Jag will be the 6th. You want to monitor IAT1 AND IAT2. Without knowing both you have no idea of how efficient your cooling system is working or whether any modifications had an affect or not.. Some of the modern cars are now monitoring a 3rd IAT as well. And you're correct, if you're not going into heat soak then there would be no need for upgraded intercoolers and pumps. However, ALL factory SC systems heat soak especially when you take them to the track because they're built and tuned for emissions standards not performance standards. Jag isn't any different. What I was asking you is if there was a preferred data logger for Jags. I'm not aware if Jag has some "hidden" data on the CANBus and didn't want to invest in a logger that wouldn't be able to see what I need to see.

If you're only seeing 11.5psi of boost then you need to readjust your bypass actuator. We had this problem with the Vettes, Camaros and CTSV's. Some of them weren't properly set from the factory and some actually went out of adjustment over time because the diaphragm gets weak. The ECU can/will also pull timing and crack the bypass valve open if its seeing IAT's too high as well as other parameters. Installing upgraded pulleys is useless unless you have it tuned. The factory ECU is programmed to pull timing and boost above XYZ. You need a tune to adjust that parameter or else the time and money was wasted install pulleys because it wont be allowed to make any more boost than what the ECU wants it to.

The exhaust on these cars are killing them. They're chocked down and way too small for the amount of power they're making and the exhaust flow needed. No different that every other factory performance car out there due to emissions and CAFE standards but for some reason Jag decided to go even smaller. You don't see 5.0L Mustangs with 2.25" restrictions for a reason. If you wanna make more power you have to let it breath. You want your EGT's reduced as much as you possibly can or else you start to anneal the valves as well as retain heat. When you're looking to make "high" HP a larger free flowing exhaust is a requirement else bad things start to happen and head gaskets go flying. No different than every other performance car out there. The law of physics is what it is.

For my initial build my plan is to separate the two cooling systems and speed up the flow through the SC, build a 3" exhaust with 200 cell CATS removing the resonators and forward silencer, swap lower pulley to add 3.5lbs of boost, then spray 100hp worth of water/meth. I expect to see 700+hp if all goes well and then will start playing with the upper pulley and tuning as needed. The great thing about DI engines is that the ECU will automatically compensate for reduced intake temps by not only adding back the timing that was lost due to higher temps but it will even "advance" timing as long as there's no knock. Its almost as if DI engine tuning was designed for water/meth. Yeah I know...not true but its one heckuva benefit. This engine was extensively tested to 800HP so stock internals will be fine. My only question is whether the transmission will hold up or need to be built up.

I see you're in Houston...I am as well. Although I travel a lot so I'm not home most of the year. I'm a road racer and drag racer but always wanted to try my hand at doing the Texas Mile. The car definitely has to be built and tuned differently but given what I'm going to do to the car and the affects of water/meth with DI I'm thinking it should make a good top speed pass without having to do all the typical "mile run" mods. Maybe we should get together sometime and you can educate me on mile runs.

 

On a side note...something that puzzles me is why Jag, Rover and BMW run excessively high cooling system pressures. This is one of the major causes of the serious cooling system failures as well as using nylon parts. Outside of quick warm up times and trying to help control emissions there is no reason whatsoever to run 30psi in a cooling system. You're engine is going to suffer a catastrophic failure long before it could ever reach a 300*F boiling point. Reducing the system pressure to 120kPa or 140kPa will reap great rewards.

 

Quote: Connecting the two systems will make them equalize. So the supercharger cooling system is running much hotter than it needs to and is saturating the SC with heat.

I don’t know anything about these mods, so feel free to flame me for that. But I do know fluid dynamics pretty well. Depending on the size of the connection between the two systems and the type of flow at the intersection, there could be negligible heat transfer between the two systems over reasonable time frames or very significant heat transfer. The setup matters greatly.

To really know for sure, I would love to hear measurements of the temperatures for both stock cooling systems in our car and how that compares to equitable stock systems with them separated. Thanks.

 

The cooling system on these cars is pressurized to 30psi. The coolant pump for the SC intercooler system is a fluid mover and not a pressure pump. Both systems are connected so there is "communication" between the two. The 200*F+ engine coolant is going to saturate the colder SC intercooler coolant due to temperature AND pressure differential. This is why you don't see other manufacturers doing this. Now on a short drive after a cold start this will pretty much be a null effect. But once the engine is at operating temperature and you shut the car down there is now direct radiant heat transfer taking place and the SC coolant is saturating/equalizing. And the longer you drive the more the equalization takes place. They did this primarily to remove a maintenance item from their checklist. Having both systems connected and utilizing the same coolant keeps them from having to deal with two separate cooling systems on service visits. But its not ideal for performance. Once I start my build I'll do some data logging and provide info. I'll also show the performance advantages of water/meth on a completely stock car and a modded car. DI engines are the perfect platform for water/meth injection. With that being said, there's a possibility in the future that I may completely remove the SC cooling system and intercoolers but that will be determined by how well the transmission is able to handle all the added torque. Btw...I'm a Petroleum Engineer so I deal with fluid dynamics everyday as well.

 

If the loop is closed (which it is) then the pressure between the two systems will equalize and there will be no pressure-based fluid transfer between the two loops.

I’m sure there is SOME heat transfer, but if the system is as described above it also seems strange to put it on two pumps and have a small interconnect only to allow complete heat transfer. They must have been at least trying to mitigate this issue, no? I really think a measurement of the temperature difference between the two systems is the only way to know for sure. I don’t know if there are loggers that can generate this data on our stock system though.

 

The water pump is supplying the volume and pressure while the SC pump is acting as a lower pressure lift pump. Even in a closed loop system one will win over the other. Convection and radiation are very real. Newton wasn't wrong. Logging the two wouldn't be too difficult but I'm not going to do it since I already know the outcome. This issue has already been dealt with many times over in other communities. I'm looking forward to the fun I'm about to have since this is my first Cat. I've gotten bored with the same ole modding of my GM cars/trucks and needed a change. Tally ho!!

 

I am also a scientist and therefore a data junkie. If I figure out how to do the measurements, I’ll report back with my findings. In the meantime, best of luck with the mods. I look forward to hearing how fast you get her going.

 

Kindred souls. You and I need to go have a beer sometime. BTW...you could install in-line coolant temp probes on the radiator inlet port and the SC cooler outlet port and then use analog gauges for a quick and cheap method.

 

Mercedes used a similar cooling system on their 55k engines. When I split mine and upgraded the SC pump, I only saw temp drops of less than 10* F compared to stock. They would both heat soak after 1 WOT blast. In FL heat anyway.

I think meth is the best solution.