Topic: Any dyno'd 4bangers yet?

[bigchelis]

I just purchased my first Wrangler: a 97 TJ with 4in superlift kit, 33's w/alloy crome wheels, 4:88 gears, automatic lockers, and already I installed the air raid cold air intake along with the spacer.
Next,
1. 4.0 tb
2. tauras electric fan
3. full exaust

Has anyone dynod their rig to get a true meassure of hp, tq increase.  After all this work if I get 20hp I would be happy.

Example my 01 cobra dynod 271 stock, but catback with x-pipe it went up to 292hp at the wheels. 

I was wondering if anyone has actually proven Hp increases, even if they are at WOT which likely no one drives a jeep that way anyway.

Thanks,

[jcsanders79]

I have the same set up 97 with 33's, 4.88's and everything you plan to do plus a chip and don't know if I would claim 20 HP?  It helped but who knows what the actual horse power is, doesn't really matter.  It will go off road though.  Your still not going to be happy with off the line power, especially if your other vehicle is a Cobra.

[jfrabat]

This is from JP Magazine...

[bigchelis]

Thank you all for the info!  If power will not improve much, how about the power curb?

Also, I know from going through 3 stroker cobra engines, 3 full exaust combos, and 3 cam options on my cobra that although HP and TQ may not increase you can effectively change the power curb. 

ex: One of my cobra engines went from 300hp at 5k rpm and peaked out at 6700rpm at 368hp, but upon cam and exaust change I lost considerable HP.  I got 300Hp at 3k rpm and peaked at 6100rpm at 345hp.  Huge difference in street driving.  The car felt extremely quicker and I was incredibly pleased. 

Consequently; I want to know if anyone has altered the power curb, im sure if you could increase the low rpm power the everyday street driving would be amazing.  I woud welcome the loss of high end power for added power low in the rpm curb anyday, especially on my Jeep.

[Jeffy]

The problem I've run into is that when you start tweaking the power band, you end up either adding more horse power to the top end at the cost of having less torque down low.  The opposite is also true.  I've had more torque down low at the cost of more top end horses.  Currently, the engine runs out of torque around 4000rpm.  I did have it where I could rev to 5000rpm freely but that was at a cost of low end torque.  Under 40mph, my Jeep is pretty peppy if you keep the RPM's up even with 35's and only 4.56's.

I'd say short of going even lower in gears, a Turbo would be the next best thing.  Small things like an electric fan, exhausts etc. will help you fine tune the powerband but it won't make up for any big differences.  Proper gearing is very important on a 4banger.  I should be running 5.38's or 5.89's with my tires.

[Clem]

... Proper gearing is very important on a 4banger.  I should be running 5.38's or 5.89's with my tires.

 I run 4.88's and 35's for a bit. It was barely adequate. I have driven a TJ with 5.38's and 35's. I did alright. I love the 5.89 and 35 combo in my YJ!

I am not really a HP or torque junkie because I have a minimum of 3,600 HP to play with at work. I can drag close to a million lbs at 80 mph all day long... 16 cylinders just make everything else seem weak. 

[jrollings]

will 4.56s be adequate for running 33's or should i go to 4.88s ??

[Jeffy]

will 4.56s be adequate for running 33's or should i go to 4.88s ??

I'd run no less then 4.88's if you're even going to go with a gear change.  The difference between 4.11 and 4.56's isn't that much.  Still even 4.88's are just adequate.  They'll make a big difference if you're used to 4.11's and 33's though.

[jrollings]

i have 3:73 right now. so should i still go ahead and go 4.88 then?

[Jeffy]

i have 3:73 right now. so should i still go ahead and go 4.88 then?

You have an auto?  I'd probably still go with 4.88's, if ti was me.  For 33's you'd be about stock and then some by going with 5.13's on a manual.  Since you don't have a OD gear, you'll want to be slightly higher if you do a lot of freeways.

[95yjman]

heh..I have 4:10s and 31s..oh ya all factory gearing.   I could use a little more power when I'm 5th, most of the time have to downshift into 4th on a windy day.

[jrollings]

so im confused u think i should go with the 4.88s but if i do alot of drivin of the freeway i should go with 4.56? yea its an auto, it sucks 

[Jeffy]

so im confused u think i should go with the 4.88s but if i do alot of drivin of the freeway i should go with 4.56? yea its an auto, it sucks 

http://4bangerjp.com/forums/index.php?topic=173

[Rob the plumber]

5.38 gears? Can you even cruise down the highway with those? I have 35's and stock 3.73's and I turn around 2600 rpm at 70 mph.

[aw12345]

33" tires, 4.56 gears equals 3000 rpm at 70mph is a nice gearing to me