Jeep Throttle body discussion (moved from a 'For Sale' thread)

[Milner]

I will have some pics up tonight, just did not have time after i got home last night.
As for 5 horse power....Statisically, that is near meaningless....you'll notice more difference if you tires were 5lbs low.

As mentioned, I would suspect there would be more difference on a built/stroked motor. But on a stock motor, those high paid DC engineers seem to know what they are doing.

THANKS Wayne, Mike, and Heath!!!!
If you want to Dyno your rig, give Heath a call.

Wayne and Mike the RME Myth Busters!:greg:

 

[waynehartwig]

Wayne and Mike the RME Myth Busters!:greg:

 

[MRJ]

I'll get the charts scanned in today so we can get them posted.

OK for more info. Keep in mind the numbers we have are not accurate for peak hp for this motor. If your thinking to yourself that Jeep claims 190 hp from the 4.0, that is at the flywheel. These tests were run on a loaded dyno for rear wheel hp. Heath had to fudge the vehicle weight numbers to get it to test. Wayne's Jeep couldn't quite pull the load that was being applied. It might be the 35" tires and 4.10 gears in Wayne's Rubicon. Heath told me a stock Mustang was not able to do it either. We also ran into the stock Jeep speed limiter in the ECU. At approximately 85 the engine would cut out to limit speed. We had to run this test in 3rd gear to avoid this.

Now for people who say this test isn't correct then. We were not attempting to find peak hp for the Jeep. We were just trying to prove the actual difference in the various throttle bodies that are available.

My thoughts on these results are, if your running a stroker motor or have head work and exhaust work done it will help to some extent. I do not believe that the Jeep ECU is magic like others and can adjust enough for these applications. I believe you would need to modify the air/fuel map via a chip or reprogram of the ECU. Edge products has done there system right in my mind. They offer a bored throttle body but it comes with a programmer to adjust to make the larger power gains they claim. I also like how companies like AEM, and Edge print dyno charts to prove the results. If you are interested in the Edge system give Heath a call at the number I listed below. He is an Edge dealer.

In all I had a great time last night meeting Marc and Wayne to get this done. This was the first time I have personally witnessed a dyno test. It was crazy hearing the 35" Baja Claws running at 4500 rpm on four steel rollers.

I want to thank Heath and his shop "Modular Madness West", for the use of their dyno. If you have a performance motor and need some work done please give Heath a call. He has built some crazy fast Mustangs for himself and customers. He just finished a twin turbo Cobra that puts out 600+ hp at 8 pounds of boost. He can be reached at 561-0963.

I also want to thank Wayne for the use of his Jeep Rubicon to run the tests, and Marc for coming over to take photos and write this up.

 

[Jay5.9L]

That's some good info. Any ideas what would happen with a hi-flow intake? It sounds like you would buy the TB for throttle responce more than a power gain. So for most of us trail riders and rock crawl its probably not the first mod on the list.

 

[MRJ]

That's some good info. Any ideas what would happen with a hi-flow intake? It sounds like you would buy the TB for throttle responce more than a power gain. So for most of us trail riders and rock crawl its probably not the first mod on the list.

For the record, Wayne's Rubicon has a drop in K & N airfilter and a catback exhaust.

 

[JoeT]

Hey Mike, I'll come get that TB after 5 today. It's amazing what one post around here can start. Not meaning that in bad way.

 

[Bone Down]

this is the kind of tech write ups I like to see.
this has value beyond measure as this will help defeat the marketing hype.

I have thought about this mod for a very long time, but never made the plunge due to a lack of presented back up data.

100 - 300+ dollars for 5 HP and 6 ft lbs torque I will put my money into other mods.

I think I could add 5 pounds of air to my tires and feel as much of a difference as this mod.

Thanks to all involved for helping the little guy (the consumer).

 

[Tacoma]

sooooo..


no testing spacers eh? heheh

 

[waynehartwig]

sooooo..


no testing spacers eh? heheh

Nope... Nobody ponied one up! And none of us wanted to drive to Ogden...

 

[waynehartwig]

For the record, Wayne's Rubicon has a drop in K & N airfilter and a catback exhaust.

Well, technically speaking, there is no exhaust past the cat to be part of a cat back system.

My entire exhaust consists of a stock header with the 2 pre cats in place. Then I moved my cat forward about 12" to get more room to put a turn down right after the muffler. After the cat, I have a highflow muffler (about 6" long and 4" in diameter) with a turn down right after the muffler/crossmember. So nothing turning, twisting, bending over the axle and around the gas tank.... Good or bad, this is what I have to clear my triangulated rear suspension.

 

[Badcop]

Nope... Nobody ponied one up! And none of us wanted to drive to Ogden...

oh yes you did just to see my smiling face

One question about all of this...

Was a stock gearing/tire size used or was the tire to axle gear uneven? 116 hp seems alot low for a stock 4.0?

 

[waynehartwig]

oh yes you did just to see my smiling face

One question about all of this...

Was a stock gearing/tire size used or was the tire to axle gear uneven? 116 hp seems alot low for a stock 4.0?

Gearing, tire size, fuel type, etc. weren't factors. Like was said, we weren't going for max power, we just wanted to see the power difference of each TB.

But I have 35" tires and 4.10 gears on my Rubicon.... I've thought abot going 4.88's or 5.13's, but I don't want to lose my fuel economy on the highway.

 

[AINT SKEERED]

Well, technically speaking, there is no exhaust past the cat to be part of a cat back system.

My entire exhaust consists of a stock header with the 2 pre cats in place. Then I moved my cat forward about 12" to get more room to put a turn down right after the muffler. After the cat, I have a highflow muffler (about 6" long and 4" in diameter) with a turn down right after the muffler/crossmember. So nothing turning, twisting, bending over the axle and around the gas tank.... Good or bad, this is what I have to clear my triangulated rear suspension.

What is the legality of this? I know it wont pass inspection but past that Im not sure. I ask because my exhaust is comprised of essentially the same parts.

 

[waynehartwig]

What is the legality of this? I know it wont pass inspection but past that Im not sure. I ask because my exhaust is comprised of essentially the same parts.

As far as I know it's not illegal, but it won't pass inspection. Exhaust has to exit past the body. I figure when the time comes, I'll make it so I can slip on a tail pipe to pass inspection and then take it off and put the turn down back on. They want the exhaust to exit past the body so idiots don't kill themselves with exhaust fumes. I'm not dumb enough to sit there with the windows up and idle for several hours....

 

[AINT SKEERED]

As far as I know it's not illegal, but it won't pass inspection. Exhaust has to exit past the body. I figure when the time comes, I'll make it so I can slip on a tail pipe to pass inspection and then take it off and put the turn down back on. They want the exhaust to exit past the body so idiots don't kill themselves with exhaust fumes. I'm not dumb enough to sit there with the windows up and idle for several hours....

Cool thanks.

 

[XJEEPER]

Gearing, tire size, fuel type, etc. weren't factors. Like was said, we weren't going for max power, we just wanted to see the power difference of each TB.

But I have 35" tires and 4.10 gears on my Rubicon.... I've thought abot going 4.88's or 5.13's, but I don't want to lose my fuel economy on the highway.

Nice read and great tech....as for bucking up for a 62mm TB, I'm still living in the $10.00 per HP formula from my SB Chevy days......

As for the fear of lower MPG with lower gears on your rig.....I've proven this theory bunk time and again. Simply put, I (as well as many others) gained 3 mpg freeway switching to 4:56 gears over 4:10's on my tired 89 XJ 4.0 with 285/75/16's (33x11). I should have gone to 4:88's because it will need to drop out of OD on the big hills due to it's tired state (200K miles). A 4.0 motor has no problem running on the freeway all day long at 2800 rpms, and as your dyno test proves, this is smack dab in the middle of the power range. This means that you will need/use less fuel to move said rig down the road at that RPM. You will feel the difference in your seat and see it at the pump.

In the FWIW column, regearing a rig to match stock gearing is a huge waste of time and hard earned money. Stock gearing is for stock vehicles, not a box shaped rig that is lifted higher into the air (creating a higher drag coefficient), running tires 5 sizes over stock (added weight and rolling resistance) plus the added calories of body armor, bumpers, winch, spare axles, full size spare, etc.

Not taking any shots at you Wayne, just wanted to address the topic of gearing vs. HP vs MPG.........too much pizza for dinner left me in the hijacking mood, you're now free to move about the cabin.

 

[mbryson]

Nice read and great tech....as for bucking up for a 62mm TB, I'm still living in the $10.00 per HP formula from my SB Chevy days......

As for the fear of lower MPG with lower gears on your rig.....I've proven this theory bunk time and again. Simply put, I (as well as many others) gained 3 mpg freeway switching to 4:56 gears over 4:10's on my tired 89 XJ 4.0 with 285/75/16's (33x11). I should have gone to 4:88's because it will need to drop out of OD on the big hills due to it's tired state (200K miles). A 4.0 motor has no problem running on the freeway all day long at 2800 rpms, and as your dyno test proves, this is smack dab in the middle of the power range. This means that you will need/use less fuel to move said rig down the road at that RPM. You will feel the difference in your seat and see it at the pump......

I got TERRIBLE mileage on my 4.0L with the 35" and 4.88's. I was speed limited to about 65 mph or the mileage would fall into the single digits.

 

[XJEEPER]

I got TERRIBLE mileage on my 4.0L with the 35" and 4.88's. I was speed limited to about 65 mph or the mileage would fall into the single digits.

Anomoly? Poor compression? Big Oil conspiracy?

I could still pull down 16-17 mpg with my setup cruising at 75 mph, 13-14 in town, with a 200k+ tired old Renix motor. BTW, what mileage did you get with 33's and 4:88's?

 

[waynehartwig]

Currently with 4.10's, 35's, AC going and at ~75 mph, I get about 17 mpg.

Last year around this time, I pulled my jet boat up to Boise at ~65 mph at 14 mpg.... 4th gear most of the way.

 

[mbryson]

Anomoly? Poor compression? Big Oil conspiracy?

I could still pull down 16-17 mpg with my setup cruising at 75 mph, 13-14 in town, with a 200k+ tired old Renix motor. BTW, what mileage did you get with 33's and 4:88's?

Never had 33" and 4.88. I had 32", 33" and 35" (for a couple weeks and a trip to Moab) with 4.10 {D30/D35). 4.88 were always with the 35" (D30/D44). I did get 18-19ish with the 32"/4.10, 16-17ish with 33" and 14-15 if I kept the RPM down (below 2700ish?). If it was higher RPM than that it would hit single digit mileage.

I towed my tent trailer with all the above setups. I could still run the canyons pretty good, power wise with whatever (the 4.10/35" kinda sucked, though, and I KNEW I was REALLY pressing my luck with the D35 then). If I still had the XJ, I'd have swapped to 4.56 and the 35" tires to drive it on the road, but there were a few 'issues' coming and I knew it (so did the buyer).