Too lazy to go figure it out real quick, haha. I haven't actually hit the rev limiter on the car, in all the time I've driven it. I also don't think I want to do it too badly considering the stories I've heard about transfer cases. But, I'm interested. Anyone know what it is exactly? 7,000? 7,500? It have one? Lol.

 

Xtyper, yes, there is a rev limiter (pretty much every newer car has one unless been specifically deleted by an aftermarket company). If I remember right, it is set to 6500 RPM. Granted, may be 7,000. If you look on your tach, you will see where there is an orange area and then a red area. Where the red and orange meet, that is the rev limiter number.

 

I haven't hit the rev limiter but I get up to 6,500 rpms in 3rd gear going up a hill here in town every now and again when the coast is clear. You want to have good oil to do this.

At 6500 the dark red starts on the rpm gauge, then at 7000 the dial is bright red.

I think the second IMT valve on the intake opens up only after 6000 rpm, not sure. My thinking is to get the engine making all it's horsepower, open it up once in a while to blow the soot out, and so that valve doesn't get stuck.

 

Patterson, a valve should open up the same amount whether the engine is at 500 RPM or 7000 RPM. If there is a difference, then you have a problem. Normally this occurs at high RPMs where the valve starts to experience valve float and the valve stem starts leaving the camshaft and it starts getting hit like a baseball and the shock of this causes the valve to go just a little further than it normally would.

 

Thermo / Patterson: I believe Thermo is talking about intake & exhaust valves & Patterson is talking about IMT valves.


Patterson: IMT valves (Intake Manifold Tuning valves) adjust airflow in the intake manifold. At high RPM / high airflow, they ensure sufficient air is diverted to the #5 & #6 cylinders, closest to the air intake. At low RPM / low air flow, they ensure sufficient air is supplied to the #1 & #2 cylinders, furthest from the air intake. I don't know what exactly defines "high" vs. "low" RPM, but I seriously doubt 6500 RPM is needed for the IMT valves to function.

 

I think you're talking about the cylinder valves. I was talking about the IMT (intake manifold tuning) valves. They are more like a 2" diameter, butterfly valve, 2 of them on the passenger side of the intake manifold.

 

dwclapp, thanks for the explanation on the function IMTs. I was just throwing out something I heard, that is one of them opens at 6K rpms. It's just an excuse to race up that hill once in a while

That said, I keep it to 6500 rpms or 6700-ish, but I don't think I actually want to hit the rev limiter. A friend of mine has an '02 Ford Focus and he hits it pretty often, it's set to 7000 rpms. I think it's a 4 cylinder Duratec.

 

Patterson, doing a little bit of research, you are not too far off. With the IMT valves, the upper one (known as the #1 IMT valve) opens in the range of 3,000-6,000 RPM (ECU determines when it should open based on need for optimizing torque output). The lower IMT valve (known as #2) opens between 5,000-6,000 RPM (again, based on optimizing torque output).

This is coming straight from a Jaguar Workshop manual that I have. I know on my car, I can feel the upper IMT valve open at 4,000 RPM every time. Granted, normally when I am getting hard on the gas, I am shooting the RPMs up there pretty well for a nice acceleration. I can't say that I have ever felt the second IMT valve open.

 

Yeah, I know most newer cars have it (well, not even 'newer'), unless removed. I was just wondering where it was. Because I'm pretty sure I've been in the high 6's without hitting it. I used to listen to music more often while driving. I know some cars have dangerously high rev limiters. And knowing my X-Type, I'd rather be sure than to find out it was at 8,000... even if I beat on it like a douchebag, haha. Thanks for the help.

 

Its around 7k, could be 6800 or 6900, I'm not exactly sure but I've seen my needle get really close to 7k before I shift when really getting on it, and not hit the limiter.

 

Yeah, the rev limiter bounces at about 7,000 RPM's I would just do it in neutral to avoid hurting the transfer case. I'm barely ever near 7,000 (mostly 6,000-6,500 max). Lucky for me, gas was cheaper in the US for a few seasons, haha. Then again, 93 octane is never really 'cheap' here.

 

The reason I do redlines up a hill is to have a load on the engine while at hi rpms. I don't think this hurts the TC because the car already has momentum and speed, so I'm not really punishing the TC like a hard launch or a burn out attempt would.

Without a load on the engine, say in neutral, I don't think it's a good idea to redline. Chances for floated valves and other hazards increase. The engine is made to spin fast, but it also needs to do something with all that power. It needs resistance.

 

During some of my more spirited drives I don't shift until close to 7k since the car needs all its power to maintain momentum in the next gear, since its under powered. So far my TC is fine, and I just drove it another 2000 miles across the country over the weekend. I'm now at 193k miles. I'm not saying beat on yours like I do mine, since its my car to beat on, and mine to fix. So far it has taken my style of driving. I dont launch hard though, and would never try to do a burnout in an awd car. I also shift smoothly, heal toe downshifting, but that's more about keeping the car balanced than saving the TC. Plus, I don't mind breaking my tc if I'm honest since that means I get to change to a VC case. I guess I'm a bad example of what most people should do with these cars haha.

 

You drove your Jag across country? Where did you go? You should have stopped in Phoenix AZ, Ha ha, I'm a good host!

I hear you on the attention to shifting. You can make the 2.5L/5 speed Jag X scoot pretty good, but you have to hit about 6000 rpms in every gear and shift fast and precisely, and drop that clutch like it's hot.

What do you mean by heal toe shifting? The momentum from the previous gear sets up the next one for continued acceleration. If you want to race this car, it's all about technique, and, in my opinion, air mods to the engine/exhaust. You can also drop weight. I removed the spare tire and jack from the trunk. I figure that I get a flat about once every three years.

I plan to eject the stock front seats and the associated heavy electric motors soon. I mentioned to you that I'm looking for light weight race seats.

Drivetrain wise, one could replace the flywheel with a lightweight carbon composite version.

After you've added some extra air pick up to the motor, and maybe use the right octane gas, your only choice for higher acceleration is to drop weight. If I've forgotten about an organic speed mod that's not about dropping weight, please remind me my brothers.

What is a VC transfer case?

 

I can attest that Patterson is a good host. We have met up when I was spending some training days in Phoenix. Now to see if I can get another trip down that way......... He he he he.

 

I drove it from FL to NM last year and again this year. I'm in new Mexico now actually, and staying for at least a year. When I said heal toe shifting I meant when downshifting, matching rev's while braking and downshifting. There is a track about 3 hours from here that does "run what you bring" time attack track day events for under 100 bucks a day so i'm going to be overhauling the driveline and brakes and getting some time on a track. Wheel bearings and whatnot. Hopefully a big brake kit. New axles and a rebuilt TC. Oh and by VC case I mean the viscous transfer case from the early 04 and older X types. I dont have traction control so I want to swap out the open differential type transfer case for the viscous case since they do a better job of distribution of power without the computer aids. I recently finished my intake and battery relocation to the trunk, and I'm running a battery that's only 15.5lbs. I suppose my seats are a bit lighter than stock, but like you I want some more proper light weight race seats up front. The light weight fly wheel is on my wish list for sure, the stock one is so heavy. Good for slow parking lot creeping not so great for aggressive driving. I really want to build a better shifter too, the stock one, even with the short throw kit I have, is sloppy and still to far for my liking. Its too low as well. I'm going to leave the engine for last, and I'm at 193k so I'd like to get to 200k on the original engine and trans before I swap or rebuild the engine.

 

Anytime Thermo, we'll hit up the legendary El Charro restaurant again.

 

Our 2.5 Liter engine may be underpowered for the car, but here is a 2.4 liter engine with 500 HP. Only the displacement is the same, but hey, design a better TC and have an AWD Jaguar monster.

https://www.yahoo.com/autos/rezvani-...590700762.html

 

Looking at some code; appears to be 6500 out of gear, 6850 in gear.

 

Makes sense that there are two values for the rev limiter. In 3rd or 4th gear I'm willing to go as high as about 6750, but need room/no one on the road. Right there I'm getting about all the HP she's got.

A friend of mine took his X to top speed. I guess that looks something like 5th gear at 6800 rpms.

https://www.jaguarforums.com/forum/x...p-speed-70215/