Camshaft specifications AJ-V8 4.0L & 4.2L
 

Just trying to get a list together of the camshaft specs from the 4.0L and 4.2L AJ-V8

Primarily to understand the difference that the VVT makes, but also to understand what gains are possible.

The supercharged 4.0L engines did not have VVT, but the naturally aspirated versions did.

The supercharged 4.2L engines also did not have VVT, but in 2006MY this changed and the VVT was added.

Only the intake cam is variable. The exhaust cam is fixed on the S/C and N/A engines regardless if VVT or not.

The intake and exhaust cams on the non-VVT S/C are specific to that engine. The intake cam and exhaust cams on the VVT S/C and N/A are the same.

There was some differences in the variable duration depending on the model engine. AJ26 = 27º, AJ27 = 47º, AJ33/34 = ??º

The lift and duration of the different cams is not published anywhere I could find, but Count Iblis did mention something

Actually the AJ26 used a 240 period profile. On the AJ27 it was shortened to 230 intake period. The new VVT system allowed this. The AJ33 went back UP in period to 240 to compensate for the ports...

Retrofitting VVT to a non-VVT engine appears to be a massive undertaking, changing the camshafts is not as bad.

In order to get a custom cam ground, we would need to know what the existing cam specs are.

So if anyone knows the specs of each variation of camshaft, please post it up here.

My other thought, is to use the VVT cams without VVT. The exhaust cam is fixed anyhow. The intake cam could be timed to make the most improvement where you want it.

In my case I have more than enough low-mid range power, if the cam timing could open up more top end, even at the expense of low-mid range power, i'd be up for it.

Obviously we are limited to the model-specific cams, AJ26, AJ27 and AJ33/34, no mixing & matching.

For the 4.0, see pp 25 of the engine repair course manual for duration and overlap
angles. The lift would have to be worked out using a dial indicator and crank angle
gauge.

The Land Rover manuals are much more detailed and may have the information
you want.

You might also consider the VVT cams, sans VVT.

Sean did this for Stu on a NA 4.0L and it resulted in more power.

Ah ha! Also found some specs in the PDF file of the X350 workshop manual.

Here is the section from the AJ26 Engine Repair Course

Attachment 110203

And regarding the 4.2L

VVT (4.2L N/A)
Camshaft Lobe Lift intake 8.50mm
Camshaft Lobe Lift exhaust 8.50mm

Non-VVT (4.2L S/C)
Camshaft Lobe Lift intake 9.00mm
Camshaft Lobe Lift exhaust 8.10mm

But can't find a similar picture or info regarding the duration

Maybe this helps.

Well yeah, that helps a lot! :)

You already did a lot of research on this XJR-99? What are your findings?

That was posted orginally by Count Iblis, so thanks for him. I have followed mostly Avos with my new cam profiles.

Cool. Found that thread here https://www.jaguarforums.com/forum/x...2/#post1113989

Cambo,

I think the biggest reason our cars feel lacking in the upper rpm range is the Eaton. Our high rpm intake temps are very very high. For efficiency reasons the supercharged cars have 0 valve overlap (IVO 5 degreees ATDC, EVC at 0 degrees TDC) and i don't think extending the duration would yield much improvement. Exhaust pressure will be traped in the cyclinder head when the IVO, combine this with Very high intake temps and you loose alot of top end. if i am remembering correctly Count Ibus posted on his website the x308 had a exhaust back pressure of 750mbr and the x350 was about 850. I think reducing the exhaust back pressure might help the cars feel better at higher rpm's, by reducing pressure trapped in the cylinder. the more restrictive the exhaust the bigger the effect as Rpm increases on the system. Our exhausts are great for low to mid rpm but suffer at the top end. I am not an engine engineer so i wont take it personally if i am 100% wrong!

The dyno for the buckethead headers a while back sorta supports my idea. No headers starts to go flat over 4250Rmp post 37.

https://www.jaguarforums.com/forum/s...q-80696/page2/

Or look at the Twin screw cars: way lower high end intake temps and gobs of upper end.

Interestingly I have just measured my exhaust back pressure, and gave about 620 mbar. This was measured after the cats but I am using sport ones so better flow. It will be hard to compare probably as the position where you measure and how has an influence on the reading, but I have to say its way lower then expected as I still use the stock exhaust with the so called restrictive squashed over axle pipes.

Avos,

Thank you for posting your back pressure #'s. from what you and other have posted i dont think the cat back exhaust is a big drawback on our cars. I think most of the pressure is from the manifolds and cats themselves. Removing the cats or replacing the cats with high flow has the advantage of removing restriction while not altering pipe diameter keeping exhaust velocity high.

In a typical motor extending exhaust usually means extending overlap. we dont want any overlap and extending exhaust duration further before BDC would cut into the power stroke. I think this may be way in the cylinder head thread linked by Cambo, Count promoted steeper ramp profiles for better lift during duration. Interesting how the latter v8's (xj33) have an even shorter exhaust cam duration most likely reducing timing before BDC (better exhaust ports too?).

You are one of the few people on the forums that has changed your cams and most likely has a much much better idea of compromise then my speculation. i see the Heaton as a much bigger draw back at high rpm then our cams are.

Without doubt the Eaton is the limiting factor on these engines. The exhaust maybe not so much, but definitely the cats.

I was interested in the camshaft specs for a number of reasons, and not limited to just the supercharged cars. We put a N/A 4.2L on the dyno recently, which had 100 cell cats, and a full exhaust, which also prompted the question about cams holding it back in the top end.

Broadly speaking, one engine that is broadly "similar" to our AJ-V8 is the Toyota/Lexus 1UZ-FE, a 4.0L, quad-cam V8. and there is quite an aftermarket following for that motor.

And there is some interesting information about the camshaft specs that are used on that engine, also for supercharged applications, you can see them here:

https://www.camshaftshop.com/products.php?categoryid=69

The specs for the supercharged engines are much higher lift and duration.

Yes I know that the cylinder head design also has an influence on the camshaft specs, so you can't just take the specs from one engine and apply them to another, but it's just to give an example.

When you look at the AJ-V8 specs and compare to the 1UZ Kelford ones, the Jag specs look very tame...

Engine builders in this country have a fairly simple formula for getting power. Big cams, ported heads, big valves. Why doesn't this "work" for the AJ-V8? Actually who's really done this with our engines?

There are more than half dozen of running engines or active projects which have other than stock cams. Most of them powered by TS. Exact cam values are very often the most protected secret in any modified engines - go and ask anything else from a drag racer and you get proper answer, but ask his cam values... :) In generally you can control intake side much by increasing boost but at exhaust side supercharged engine likes high lift, which can be close to the intake cam values. AJ SC engines have quite shy cam values, especially 4.2 with 220degrees/8.1mm ex cam. This way you get very nice idle, strong low rpms and low emissions 400hp engine. If your goal is 700hp, that's really a restrictive point. But....SC issue comes always first. Way before any cam change. Eaton is always Heaton. TS powered, quite high mileage 4.0 engine with stock MAF and TB = quite low boost, has made basically same dyno numbers as overspinned Eaton based, fully rebuild 4.4 ( yes, 4.4 ) engine with ported heads, quite agrressive cams, headers, bigger MAF + TB and aftermarket ECU.

Stock pistons, specially the 4.2 style, have limitations for the cam lifts. BIG cams need deeper valve pockets for safe operation than there are on the stock pistons.

would more exhaust cam duration Before BDC help reduce back pressure and allow for a slightly better reeving SC engine? I would love to know the cam spec's for your GT3 heads! The SC kelford cam Cambo linked (gotta love the 6 bolt mains of the uZ1) had overlap, i am unclear if overlap is a better compromise for high RPM then earlier EVO BBDC. Overlap would also reduce (eliminate?) the internal EGR with zero overlap. Either change would be a reduction in low end torque and most likely an increase in emissions. I would be very curious what the heads like as a more mild street cam.

5.0 AJ133 cam specs:


Intake valve lift: 5.5-10,53mm .
5.5mm from idle to 2800-4825rpm - load dependent. Outside this area 10,53mm ( Camshaft Profile Switching }
Exahust valve lift: 9.53mm


Intake duration can be altered by 62 degrees and exhaust by 50 degrees.
Variable Camshaft Timing VCT

I would be interested to know the actual timing info at full load from the 5.0 SC cars.

I see that with the IDS you can measure the VCT settings, so it would be great if someone could do this measurement!

The exhaust cam has 9.36mm lift - not 9.53mm.

From the lifts you've given me (They INCLUDE the ramps BTW) I can tell you what the durations are. When I started work on the AJ133- we were using different- shorter duration cams and a CPS system. The lifts you quoted indicate what they settled with after I left.


The 10.53 mm lift intake cam (with CPS) is a flat tappet 250 duration cam (measured top of ramps)




The 9.36mm lift exhaust cam is a 250 duration also (non CPS) for the exhaust.

One of the things we've looked at for the AJ33S was the possibility of retarding the intake cam somewhat, maybe 20deg or so. Sure it would be at the expense of low-mid range power but frankly there's plenty of that, it's at the high revs where it runs out of puff.

Some testing on an AJ40 (X150 XKR) by changing the VVT operation in the tune showed that this should bring some gains in an AJ33S which has no VVT, in essence we put the intake cam in the same position that a VVT AJ34S / AJ40 would be in the upper rev range. With the cams "locked" in the tune on the AJ40 it was still pretty good in the low-mid range, but still made the better top end power.

Your thoughts on this idea Count? Just looking to squeeze whatever we can out of the AJ33S (non-VVT) in the 03-05 XJR and STR...

https://cimg0.ibsrv.net/gimg/www.jag...ff7b86ff37.jpg



Cambo, I don't recall what the profile used was on the AJ40 (AJV8 SC with VVT). It had VVT so the fully retarded position (no oil pressure) was probably around 140 +.


On the fixed valve timing AJ34 SC we did full VCT sweeps however away from the 120 IMOP we arrived at.


20 degrees is way too retarded- you'll lose power.


I dug up some dyno runs of 120 MOP (stock set up), 125 MOP and 130 MOP.



The 125 MOP isn't even worth doing- the gains would vary depending on tolerances of the car and you'd be lucky to notice it.