Dyno Test - What's wrong ?

[Cjmartz2k]

Yes, you have both a rev limiter and a speed governor. I think there is a thread somewhere on here about top speeds, and I think your rev limiter is 5k or 5200K, but I think the only way anybody haas found to adjust them is a hypertec programmer.

 

[Panama XJ]

I hope Priandi is OK after the earthquake, send a message to let us know you are OK, good luck

 

[tealcherokee]

theres no reason to change your rev limiter, its theres because of valve float, which happens around 5400 rpm

 

[Cjmartz2k]

It'll float with a stack valvetrain, which I'm not sure if he has. Harmonics is the real reason you can't rev an I6 to high. I think 5500 is the practical limit, but I'll bet Dino will comment.

How close was the earthquake to Jakarta? I hope he is alright also.

 

[tealcherokee]

na, i know someone who started w/ a renix jeep, and so far as the stroker done, extensive head work, hes revving to 7350, hes also trying to get 500whp w/ a blower pushin 8psi

 

[Dr. Dyno]

It'll float with a stack valvetrain, which I'm not sure if he has. Harmonics is the real reason you can't rev an I6 to high. I think 5500 is the practical limit, but I'll bet Dino will comment.

How close was the earthquake to Jakarta? I hope he is alright also.

Me too.
The stock valvetrain is the limiting factor as far as maximum rpm goes and with the stock valve springs, valve float occurs somewhere around 5500rpm so the rev limit is set somewhat lower than that to protect the engine from piston to valve contact.
With stronger valve springs, you could go a bit higher but since the bottom end is cast iron, a stroker is still effectively limited to 5750rpm due to the piston speed.
Most strokers will be producing maximum HP at less than 5000rpm. Given that maximum rpm is usually set about 10% beyond maximum HP rpm, a rev limit of 5500rpm is as much as you're ever going to need.
Priandi's rev limiter seems to be coming in at 4850rpm. With peak HP coming in at less than 4000rpm, it would be pointless to raise it at this stage. As far as fuelling goes, the current set up is right on the money and the stock fuel pump will do fine.

 

[A Satria]

I hope Priandi is OK after the earthquake, send a message to let us know you are OK, good luck

WOW, Thanks for your concern...:worship:

I live in Jakarta (Capital City of Indonesia), and nothing happens in Jakarta at all.
The earthquake happens in Jogyakarta (2 hours flying from Jakarta). I went there on Sunday, and YES, it is a mess !!!
Wish us luck,...

JAKARTA, Indonesia (CNN) -- Emergency food aid arrived Sunday in two hard-hit districts of central Java, about 36 hours after a massive 6.3-magnitude earthquake flattened communities in the heavily populated Indonesian region, killing more than 4,500 people and displacing 200,000 others.

Indonesia sits on the Asia Pacific's so-called "ring of fire," marked by heavy volcanic and tectonic activity. Scientists worried about the impact of the quake on Mount Merapi, which villagers have watched closely in the past few weeks before the quake.

The earthquake is the worst disaster in Indonesia since the December 26, 2004, magnitude-9 earthquake that triggered a tsunami (mostly in Aceh), killing at least 131,029 people in Indonesia alone.
Another earthquake on March 28, 2005 killed about 900 people off the western coast of Sumatra.

 

[A Satria]

Me too.
Most strokers will be producing maximum HP at less than 5000rpm. Given that maximum rpm is usually set about 10% beyond maximum HP rpm, a rev limit of 5500rpm is as much as you're ever going to need.
Priandi's rev limiter seems to be coming in at 4850rpm. With peak HP coming in at less than 4000rpm, it would be pointless to raise it at this stage. As far as fuelling goes, the current set up is right on the money and the stock fuel pump will do fine.

Dr. Dyno,
OK, since my Peak is still below 4850rpm, that means I do not need to worry about max RPM Rev-Limiter YET !!!.
I'll put a temporary Fuel Pressure Gauge to see whether the pressure are within the range during idle, and engine rev.
What should be the fuel pressure ?, I might need to change with the adjustable fuel pressure regulator if the pressure is not stable during the test.

Thanks,


-Andhi-

 

[A Satria]

As of Monday,

1. Cherokee FRONT Coil Spring and Shocks will be replaced with WALKER EVANS Dual Coils Coil-Over Shocks - Adjustable, with remote reservoir Set-up, 8" inch travel
2. Cherokee REAR Leaf Spring and Shocks will be replaced with WALKER EVANS Dual Coils Coil-Over Shocks - Adjustable, with remote reservoir Set-up, 10" inch travel
3. Coil Over Shocks - Walker Evans Products
4. Coils - King Springs
5. It will takes approx 2 weeks of cutting, welding, etc

XJ will be lowered :

1. Front 1-5 to max 2inch
2. Rear 2-3 inch
3. Again, it all depends on what can be done during the modifications.

 

[tealcherokee]

glad your ok

the coil overs look cool, way too much travel though, with my jeep lowered 2" i have 1" down to the bumpstops (oil pan is like 1.5" down) and 2" up travel when the coils will unseat, so i have 3" of travel, id look into something with less travel.

Ill try to remember to get you some axle to body measurements so you can see if the coils are going to fit

 

[A Satria]

Coil Over Shocks, Walker Evans Shocks

glad your ok

the coil overs look cool, way too much travel though, with my jeep lowered 2" i have 1" down to the bumpstops (oil pan is like 1.5" down) and 2" up travel when the coils will unseat, so i have 3" of travel, id look into something with less travel.

Ill try to remember to get you some axle to body measurements so you can see if the coils are going to fit

OK. GOT YOUR POINT....
So, you have 3 inch of total travel...

I confirmed to use 6 or 8 inch total travel all around.

• Compression from Ride Height to Full Compression 2 inch (i'll cut the bump stop)

• Rest of travel will be used for up travel (6 inch or so) - depends on shocks !!

• The reason for 6 inch
  • I'll have the car for DUAL Purpose Street Show.
  • On Saturday, it will ride on 20 inch wheel and lowered 1-2 inch from standard Height, then
  • On Sunday, it will ride on 15" Bead-Lock Walker Evans Wheel on BFG, and Raised 2" from Standard Height. The car will be placed on FULL ARTICULATION to show the benefits of coil-over applications.
  • The "JIP" magazine in indonesia will write-up a cover about this car along with the Thread discussion.

• It will use 2 6-inch coils (for dual rate set-up). The top coil (primary coil) will be very soft and the lower coil (secondary coil) will be stiff. using this combination I am expecting the shocks shaft to have 2,5 inch of area for compression with the secondary coils as the ONLY coils used for the remaining 2,5 of compression stroke.

• The top (primary coils) will be used mostly for up-travel and/or during full axle articulation, and the first 6 inch of travel from extended lenght to ride height lenght.

• The rear need a STIFFER SWAY-BAR during On-Road to eliminate Body Roll (mainly due to lenght of extended shocks up-travel lenght, Dual Coils lenght uncompressed, etc)

• I'll post updates, such as ;
  • the weight of XJ on each wheel foot print area, total front weight, corner weight, rear weight, etc.
  • Combination of dual coils (top and lower) which include each coil spring lenght, each coil spring rate, combined dual coils spring rate, as well as Rebound rate and Compression rate for the shocks itself.

• It will be on JIP (indonesian) Cover Magazine with title "City Slicker"
  • The first STREET DRIVEABLE Cherokee with
    • All Coil-Over Set-Up
    • Moderate Engine Modifications for on-road, Off-Road
    • Clean/ all Leather Interior
    • Clean Paint
    • Moderate Exterior modifications
    • "SLEEPER" look, with performance underneath

• (admin or moderator), would it be ok if I put LOGO on the XJ during Photo Session ?
• Guys, I'll be putting your names on the side Rear Windows also, would it be OK ?

 

[Dr. Dyno]

Dr. Dyno,
OK, since my Peak is still below 4850rpm, that means I do not need to worry about max RPM Rev-Limiter YET !!!.
I'll put a temporary Fuel Pressure Gauge to see whether the pressure are within the range during idle, and engine rev.
What should be the fuel pressure ?, I might need to change with the adjustable fuel pressure regulator if the pressure is not stable during the test.

Thanks,

-Andhi-

Since yours is a '97, the fuel pressure should be ~49psi and remain stable. If the fuel pressure starts to drop at higher revs (unlikely), you'll need to upgrade the fuel pump. An adjustable regulator won't do you any good so don't waste your money on it. If you need to change the fuelling at any rpm point, you have the Unichip to do that for you.

 

[streetpirate]

best i can remember the nasty harmonic in 4.0's is at 6250rpm

 

[tealcherokee]

xj's wont hit above 5500 ish with out stiffer valve springs......

 

[A Satria]

best i can remember the nasty harmonic in 4.0's is at 6250rpm

How's your project XJ coming up ?

 

[streetpirate]

mmm good. money ran out, not hungry just broke. suspensions all done exept for sway bar bushings, rough over speed bumps but goes arond city block corners at 45, and theres a 6 mile section of 25 mph corners that i can take without going under 60, but i havent pushed it yet, been wet out.
i have this concern that it may need more power.

 

[A Satria]

Hi all,

Sorry that the ENGINE MODIFICATIONS has to wait for another weeks or so.
At the moment I am doing a major modifications on Suspension.
Next week it should be FINISHED and will be ALL Coil-Over SHocks.....

Detail discussion thread on
http://www.naxja.org/forum/showthread.php?t=87268​

 

[A Satria]

fbthrottlebodies[/size].com ]

Your Dyno thread was very interesting!
Our experience (F&B) is that the Mopar ECU runs on the rich side under almost all conditions within +/- 30% of "nominal".
For example: a stock 5.9l rated at 245 hp can be modified with additional air flow /Volumetric efficiency items like camshaft, big valve/port heads, high flow short runner intakes and high flow throttle bodies to make about 400hp on the stock PCM and injectors.
After that it is best to get a reprogrammed PCM or interceptor type system to deal with the larger injectors required at that output level.

The Jeep 4.0 is similar in that the stock PCM/injector combination is very capable of about 20-30% increase in VE without reprogramming or increasing injector size/inlet pressure.
By adding stroke to your motor you have potentially increased the VE by 12% or so. This is well within the stock injector pulse width /duty cycle capabilities as driven by the stock PCM.
Addition of a high flow exhaust, cold air intake, reground high lift cam and or ratio rockers will increase the VE another 10% or so, pushing you into the need for an intercept system if the Jeep is to be driven really hard!
The addition of our high flow throtlebody will definitly help with your VE problem.

But I think you are running too much Injector pulse width if the +46% is real! Pull the fuel back and watch the HP/torque increase! to run our 66mm TB you will need to port your intake manifold inlet to 66mm.
Shoot for 14.6:1 A/F ratios under light load and about 13.2:1 under full load!

We can definitly ship to Jakarta. Our factory direct pricing is USD $365.00 + $33.75 shipping via USPS Global Express 3 day. We can take moneyorders by mail (address: F&B Performance, 406 N. Cedros, Solana Beach CA 92075 USA) , or Paypal payments to account: <A href="mailto:[email protected]">[email protected]

We do not accept credit cards, however our distributor <A href="http://www.hesco.com/" target=_blank>www.hesco.com does!

Please feel free to email with any other questions.

Thank You,
Bruce K Bridges (www.fbthrottlebodies.com)

1. Such a responsive response from the company. :thumbup: :thumbup:
2. Should I get the 66mm or just go direct to the 68mm ?
3. Should I pull the A/F ratio back to get 14.6:1 A/F ratios under light load and about 13.2:1 under full load! ?

 

[Dr. Dyno]

1. Should I get the 66mm or just go direct to the 68mm ?
2. Should I pull the A/F ratio back to get 14.6:1 A/F ratios under light load and about 13.2:1 under full load! ?

Go direct to the 68mm and enlarge the intake manifold plenum opening to match.
As far A/F ratios go, the answer is yes. The engine makes the most power when the A/F ratio is around 13:1, while it gives the best fuel economy and emissions under light load when the A/F ratio is a stoichiometric 14.7:1, so the answer to the question is yes.

 

[5-90]

Since this thread has been resurrected, let's note a point of historical fact here...

Interesting, no? For devotees of trivia, I seem to want to recall a turbocharged Cummins six running at the Brickyard years ago as well... Did well in qualifying, but DNF, as I recall.

5-90