djb383

Talk about a tight wad.....here's your chance to be "da man".....pony up, prove 'em wrong, we'll all benefit. JPM's advise/info was free.

Did the Daimler dudes design a '99+ intake for a '99+ XJ or a '98 down XJ?

Programbo

"Daimler dudes?" No the guys in the garage who produce the JP rag are "dudes". The guys who work at Daimler AG are automotive engineers. They designed it for the XJ 4.0L engine. Besides I have the feeling you wouldn't believe the results even if I did do the swap and run a dyno and see a HP increase. Not sure why I think that just a feeling I have.

djb383

....but what year(s) XJ did those dudes design/make the intake for.....'99+ or '98-????

I have a feeling if u prove the JPM myth busting results wrong, u could sell those few '99+ intakes u have for a premium.....heck I might even be interested in one. I have no reason to disbelieve your results and no reason to believe u would try to deceive me or the other forum members.

Just keep it simple......a '99+ intake on a bone stock '98- 4.0L.

All I'm saying is, JPM post their dyno results after swaping nothing more than the intake manifold on a stock 4.0L motor. The only other dyno results we have are in the link u post and those results are on a highly modified 4.0L motor (big time apples oranges). After those 2 dyno test results (one intake only swap and one intake on a highly modified motor swap), all we have is opinions.

Have any of the engineers at Daimler or Edelbrock said/claimed/proved what a '99+ 4.0L intake will do on a stock '98- 4.0L?

We have tons of motor oil myths out there......would it be totally impossible that there could be a intake manifold myth as well?

JeepCoMJ

You are arguing using incorrect theory.

Fact. Increasing intake volume will increase fuel atomization and thus combustion ability.

Fact. Doing so will necessitate an appropriate increase in fuel delivery directly relative to the change in hp/torque curve.

Fact. Doing so also will increase necessity to increase exhaust flow. Not necessarily size, but flow. I.e. nicer headers.

Myth. Cone filters without shielding count as cold air, and will result in any improvement.
Myth. Throttle body spacers work on mpfi. They dont. They work on preatomized fuel delivery systems. I.e. tbi, carb. Reasons are logically that minute increases in incoming airflow will result in increase in power. The 99+ manifold increases volume x2.

Myth. More power = less economy.
Fact. Power to weight dictates economy, to a point. Too much will guzzle fuel. There are always limits.

djb383

The only thing I'm arguing with/questioning, is yours and others opinions. We all have a right to argue with/question anyones opinion, no? If u post an opinion, post your data to back it up and the source of your data.

I would argue with/question JPM's post IF......it was their opinion and no data to back their opinion up.....but since their dyno test results was of a apples to apples intake swap only on a bone stock 4.0L and the results they post was based on dyno tests/results data, not opinion, I'm hesitant to rush out and buy a '99+ intake and install it on our '98 XJ.

From JPM's "Myth Busting" article:

'99-Up Horseshoe Intake
Myth: According to that great wealth of information that is never wrong, the Internet says you'll get a 5-30hp gain thanks to the '99-up 4.0L's swooped, equal length runners and larger plenum volume.
Our Thoughts: While a free-flow intake manifold can deliver more power, it's only going to allow as much air to flow as the cylinder head and camshaft will call for. Upping the intake runner volume too much will cause the intake charge to lose velocity, killing low- and mid-speed power and torque. On a '98-earlier engine running a stock camshaft and unported cylinder head, it's wasted effort.
Claimed Gains: 5-30hp
Actual Gains: 5hp loss on Trasborg's '98 XJ (Project Mileage Master)

Do u not understand the Kings English as to what apples to apples means, what bone stock unmodified means, what dyno results/tests means, what theory means? I'm beggin' for someone to do the exact same intake manifold swap test that JPM did and prove, with valid data, that JPM is wrong. So far the only thing proven is JPM's dyno results showing a 5 hp drop......................and that people have opinions.

This is getting old.

junglejuice

Hi all, I'm new on here but have been on Ausjeepoffroad since '03 and have been tinkering with my Xj since I bought it in '03.

A little about my 4.0 litre, it's a 95 sport which made it an OBD1, when it was stock standard, I mean tyres, suspension, everything even while empty I used to get noticable pinging on a warm day on even the slightest incline so I started looking into this, if I ran on premium fuel it was fine but here in Australia premium fuel is not available everywhere especially in the outback.
First up was a TBS, yes I have read all about how they don't work and are a waste of time an money, I made my own out of 28mm thick Ralloy so it cost me nothing except time, pinging gone after this was fitted, despite the "internet facts" stating that these DON'T work.
After about a month the pinging returned but at a reduced level.
I then fitted a snorkel and found zero difference in every way.
I then swapped in a machined throttle body, it was fre and I have access to a lathe so why not? No noticable change in any way.
I then fitted a set of extractors with 2.5" muffler and cat with 2.25" tailpipe, sounded better and maybe slightly improved performance but the pinging issue remained.
I replaced the O2 sensor, no change.
Same with plugs, leads, cap, rotor, filters, no change still pinging.
I also removed the engine fan and fitted twin electric units.
As I had a big trip planned towing a 1000kg camper trailer with no premium fuel available I had to get this sorted so I fitted the 99 intake despite reading the JP magazine article.

FIXED!!!!!

This I know is anecdotal and others are allowed to disagree but I KNOW it worked on mine, I was able to tow my trailer in the heat with the Xj fully loaded on standard fuel running 30" tyres still stock gearing and never suffered any pinging at all, the performance was like it used to be when running on premium fuel which it could never get previously on standard fuel.

I later found that the OBD1 engine was down on compression so I don't know how much this affected the results I saw but the FACT remains that the TBS and 99 intake fixed my issue, I don't need a dyno to know this.
I have since fitted an OBD2 engine from a Zg and there is a difference between the two variants of 4.0 litre engines between OBD1 and OBD2 in regards to head design and cam profiles as well as a different torque curve, OBD1 peaks at 3950rpm while OBD2 peaks at 3000rpm.
I have also acheived my best ever fuel economy (dead empty car) with the OBD1 engine with the above mods and regeared to 3.73 (from 3.55) and the stock 225/75/15 tyres 10.1 litres per 100 kilometres (US23mpg, 28mpg) which I couldn't get near previously.
I have now swapped the entire wiring loom for the car over to an OBD2 loom along with the PCM and sensors etc and noticed better performance and better real world fuel consumption since the swap but this is using the stock 96 manifold etc as I wanted to get to know the OBD2 characteristics before trying the mods again but still running the same exhaust and snorkel.








Cheers, JJ

salad

I'm impressed with and inspect your work but dude, a stock engine pinging on regular fuel means something is seriously wrong...

odgreen

Lean ping..... lets try to fix it with a bunch of random ****! But never suspect the injectors....... lol fail

junglejuice

Those injectors were still in the car until I swapped over to OBD2 and never gave any issues so if it were the injectors swapping the manifold wouldn't have fixed it would it??????????