OP
2.5 throttle body to 4.0 throttle body
- Thread starter Tinytim14
- Start date
OP
M35A2
TJ Enthusiast
Yep that's her. She's a very fun/great lady. I didn't know she had picked up the nickname Mayhem Marianne though, how fitting lol.
M35A2
TJ Enthusiast
Very cool. She seems like a really good person. Reminds me of my friend who infected me with the Jeep bug.
And I don't know if she actually uses that nickname but that's what they call her on the show. Could just be for "TV effect"
Howdy ya'll. I am not a TJ owner but i feel this is very relevant me. I have a 4cylinder YJ 1995. The engine was just rebuilt with a 505 stroker ( i know how some people feel about trying to add power to a 2.5). My issue is that the guy who rebuild the engine did so for free. I took what he offered and suggested. That is why i have the stroker and not a 4.0 engine( as i would have hoped). Any way I know i have a cold air intake, 4.0 TB but I am sure the TPS is the 2.5. Do i need to change the sensor. I ask because the jeep runs sluggish intermittently, surges at idle, Jerks while accelerating. I don't have CEL and I don't have an OBD 1 to check codes. I am thinking TPS, rejetting, MAP and possibly O2 SENSOR. The only new mods was a 4 inch lift, SYE a CV drive shaft. New winch. I run stock axles and 31 inch tires. I live in Colorado so i know i wont be running marathons on the highway i just want my jeep to run smooth when i drive her.
Sounds like you got too much cam. Pretty much all rookie engine builders try to stuff in a cam that makes "huge" power gains. The problem is those gains are made above 5,000 rpm. And you run a Jeep at under 3,000. My first (car) engine build was a 2.3L in a Ford Mustang. On paper with the super pistons and ultra lumpy cam and 4v carb I should easily double the horsepower. Problem was these parts were ment for the turbo SVO engine and I didn't put a turbo on it. It had a crap idle. And crap acceleration until I got above 3,000 rpm. But after that... holy crap did it move! Just not on the street. In town it was miserable at best. It got sold within a week or two. Back then there was no internet. Just what a magazine article might allude to. Only way to get power from a 4 banger is from better induction.
As for a V8, I still think the old school 350 with a TBI is a really great way to make dependable power. I have yet to embrace all the sensors and missing distributors we have today (although I am aware they are better).
As for a V8, I still think the old school 350 with a TBI is a really great way to make dependable power. I have yet to embrace all the sensors and missing distributors we have today (although I am aware they are better).
Never underestimate the abilities of a stock Jeep.
Nothing wrong with a 4 cylinder Jeep, my daily driver for years was a stock '80 CJ5 with the GM 2.5 4 banger. I drove it everywhere and anywhere I wanted to go just keeping in mind that it wasn't "Super Jeep".
Nothing wrong with a 4 cylinder Jeep, my daily driver for years was a stock '80 CJ5 with the GM 2.5 4 banger. I drove it everywhere and anywhere I wanted to go just keeping in mind that it wasn't "Super Jeep".
I love my 4 banger, the guy who rebuilt the engine is a master mechanic. He did for me as a favor to my father in law. I asked for a little more power to handle the hills we have in colorado for street driving. I know I will never be running marathons. The way it behaves sounds like a TPS. I just want to know does the TPS have to match the throttle body. IE: 4.0 to 4.0.
I swapped in the 4.0 throttle body several years ago and all the threads on this suggest swapping all the sensors, I did.
I know this post is old, I had a 2000 Cherokee with a 2.5 5 speed with 4.10 gears factory. I added a 4.0 throttle body after installing a clay smith 264 duration cam and 24lb accel injectors. Don’t let anyone tell you these engines don’t respond. My 2.5 embarrassed many vehicles and would outrun a stock 4.0. I later rebuilt the engine after running it 150k and ported the head. That made a around another 20hp increase with the rebuild and would bury the speedometer getting on the highway. I traded the Jeep and a built 406sbc for a 52 coupe but the old Jeep has been spotted a few times out since. Not sure what the throttle body would do on a stock engine other than free up some hp. I also had a cat back system and an open element air filter and an msd 6a. Hope this helps someone on another post
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Ok guys...I read all the posts, and I have to basically agree with the what Chris and Jerry posited...
Just sticking a 4.0l TB on a 2.5L manifold is pretty much worthless...UNLESS...
1) You hog out the manifold opening to match the Throttle diameter of the 4.0 TB.
If you don't do that, well, you just wasted money for the TB...
Hogging out the manifold is a start...there is a minor increase in torque, but not much.
2) Hot Rodder's credo...More air in = more burnt fuel out...and more power in between.
Get a Cold Air Intake (Air In) and line the supplied barrier with aluminum muffler tape
on the side facing the engine to reflect the heat...it helps a bit...
f.y.i I recorded an intake temp of 178F with an outside air temp of 82F...
Dunno what the Temps would be with a stock manifold.
But HUH?
But at least the airflow is better (sure, the stock intakes "sound" good, what with
the resonators amplifying the sound to give a "whoom" sound, without the power.
But, read on, we are going beyond stock.
Would a Scoop would lower the intake temps, thus denser air into the engine?
Good thought, will look into that.
3) Definitely install proper headers (Banks, AeFe, et.al.) to satisfy the equation (flow in = flow out).
4) Now to the "air in" part:
I have 0.60 shaved heads with oversized valves...
CAVEAT: when you get the milled/O-size heads, replace the valve springs back to stock!
The springs that were supplied with the heads destroyed my lifters and push-rods...
Stock pressure is 140 lbs FULL open...the supplied springs were 140 lb TO open!!
Brought that to the attention of the supplier...and they blamed me for not "soaking"
the hydraulic lifters?! BULL!
HUH...soaking, as in filling the lifters with oil...ya, but dont'cha think the excessive
spring pressure on full open is not a factor???
...good way to destroy the lifters AND the push-rods!
WHICH IT DID...had to do a rebuild...no thanks to the supplier!
5) I installed an aftermarket plug-in module that took into account the mods.
That worked really really well (Jet Performance (www.jetchip.com) ...
At first I used their base 2.5l Stage 1 module...
Smoothens the idle, the mileage improves, and driveability is much better...
The 2.5L stage 2 upgrade is the one to I use, given the mods...
6) Seal all vacuum leaks...that is pretty much a given.
Having done all that, I do have more torque, and there is a hp increase
(hp and torque are related, but not the be all and end all of driveability and good mileage).
The Torque increase is noticeable with normal driving (hoping for best effect on the highway,
with a bit of a headwind bringing my hwy mpg down!)
My city mpg is solid at 16 mpg and will check the hwy mpg this weekend and report.
So...Throttle upgrade for the 2.5L...do the above, and it does work...
Wanna spend the money?
Ya, if you are one of us, who just like to "tweek" what we got, and get
the satisfaction of "I did it...a job well done!"!
But, over all, donch'a know...we doing love it...
It's a Jeep thing!
To the naysayers:
Sure, the ECU will control for optimum, but...
wirh these mods, It will control optimum fuel/air ratios for the denser (higher cfm) air charge,
and relate it all to the closed loop...
Give it more to work with, and you get the optimum
burn for the increased flow in and out...more input fuel/air/higher + compression in = more power out,
Add the performance module to the ECU and "bob's your uncle"
And that should be that...any further mods = money down the drain...
Sorry, but that is the truth...
Just sticking a 4.0l TB on a 2.5L manifold is pretty much worthless...UNLESS...
1) You hog out the manifold opening to match the Throttle diameter of the 4.0 TB.
If you don't do that, well, you just wasted money for the TB...
Hogging out the manifold is a start...there is a minor increase in torque, but not much.
2) Hot Rodder's credo...More air in = more burnt fuel out...and more power in between.
Get a Cold Air Intake (Air In) and line the supplied barrier with aluminum muffler tape
on the side facing the engine to reflect the heat...it helps a bit...
f.y.i I recorded an intake temp of 178F with an outside air temp of 82F...
Dunno what the Temps would be with a stock manifold.
But HUH?
But at least the airflow is better (sure, the stock intakes "sound" good, what with
the resonators amplifying the sound to give a "whoom" sound, without the power.
But, read on, we are going beyond stock.
Would a Scoop would lower the intake temps, thus denser air into the engine?
Good thought, will look into that.
3) Definitely install proper headers (Banks, AeFe, et.al.) to satisfy the equation (flow in = flow out).
4) Now to the "air in" part:
I have 0.60 shaved heads with oversized valves...
CAVEAT: when you get the milled/O-size heads, replace the valve springs back to stock!
The springs that were supplied with the heads destroyed my lifters and push-rods...
Stock pressure is 140 lbs FULL open...the supplied springs were 140 lb TO open!!
Brought that to the attention of the supplier...and they blamed me for not "soaking"
the hydraulic lifters?! BULL!
HUH...soaking, as in filling the lifters with oil...ya, but dont'cha think the excessive
spring pressure on full open is not a factor???
...good way to destroy the lifters AND the push-rods!
WHICH IT DID...had to do a rebuild...no thanks to the supplier!
5) I installed an aftermarket plug-in module that took into account the mods.
That worked really really well (Jet Performance (www.jetchip.com) ...
At first I used their base 2.5l Stage 1 module...
Smoothens the idle, the mileage improves, and driveability is much better...
The 2.5L stage 2 upgrade is the one to I use, given the mods...
6) Seal all vacuum leaks...that is pretty much a given.
Having done all that, I do have more torque, and there is a hp increase
(hp and torque are related, but not the be all and end all of driveability and good mileage).
The Torque increase is noticeable with normal driving (hoping for best effect on the highway,
with a bit of a headwind bringing my hwy mpg down!)
My city mpg is solid at 16 mpg and will check the hwy mpg this weekend and report.
So...Throttle upgrade for the 2.5L...do the above, and it does work...
Wanna spend the money?
Ya, if you are one of us, who just like to "tweek" what we got, and get
the satisfaction of "I did it...a job well done!"!
But, over all, donch'a know...we doing love it...
It's a Jeep thing!
To the naysayers:
Sure, the ECU will control for optimum, but...
wirh these mods, It will control optimum fuel/air ratios for the denser (higher cfm) air charge,
and relate it all to the closed loop...
Give it more to work with, and you get the optimum
burn for the increased flow in and out...more input fuel/air/higher + compression in = more power out,
Add the performance module to the ECU and "bob's your uncle"
And that should be that...any further mods = money down the drain...
Sorry, but that is the truth...
If you want more power, you have to open up the entire pathway. Slapping a bigger throttle body or an air intake on is effectively useless.
It's pretty simple if you think about it.
Of course if you do that, you also need to tune it, because adding more air also usually means adding more fuel.
It's pretty simple if you think about it.
Of course if you do that, you also need to tune it, because adding more air also usually means adding more fuel.
The stock filter flows more than the engine needs. Switching to a CAI will just give you poor filtration and gunk up your newly ported intake.
Hi All...
Well, yes, as Chris said, just tossing a 4.0L TB on a 2.5L manifold does nothing except lighten one's wallet.
In my thread, I described the mods that were necessary to complete the job...But I am re-threading (?!)
to clarify my process.
As an aside...the $$$ is high, and while my 4-popper was running fine
(although I did add Banks headers early on), I put off the mods until I needed a rebuild
(AFTER 168,000 MILES!)...then the $$ becomes more rational, considering the $$ of the overhaul, the extras are a smaller increase percentage of the $$ outlay
That was my chance...So, my plan came into effect...
My install process:
1) Ported Heads shaved 0.60" with O/Sized Valves.
CAUTION...The supplier of the shaved & ported & o/size valve
heads included unsuitable valve springs installed...
Stock springs are 140 lb max at TDC
Theirs were 140lb TO OPEN!
needless to say, my lifters & pushrods were destroyed.
And they claim it was my fault for not "soaking" the lifters?
Bull...just take a look at the resulting TDC spring pressure, for pete's sake!
btw...not the first time I did an overhaul...that excuse was B.S.
That being said, the heads were beautiful!
2) Hog out the opening to match the 4.0L TB (I bored mine to match the Gasket @ 62mm)
3) Four-hole injectors (from a Ford Bronco).
(4-hole gives finer atomization of the fuel, and, yes, although the ECU keeps the
Fuel/Air ratio at optimum (after the fact), the better automization means more vapourization,
which means more complete burning within the cycle (I got better gas mileage).
4) AeF Headers to replace the cracked ( poor things, after 6 years of service in our Cold Canadian Winters,
90 miles north of Fargo, Minn) Banks Headers. (They were on sale)...
5) Yella Terra Rockers...(every bit helps, besides, this was a "candy" purchase that I wanted, so there!)
6) "Cold Air" Intake...It looks good, but there are problems...
It ain't cold air!...even with putting silver reflective tape on the blocking panel side facing the Engine,
in hopes of reflecting some of the heat.
I measured (contact mount Type T Thermocouple ) the temperature of the intake pipe half-way, and found
that the temperatures were only a few (ignorable) degrees from the MIT Sensor...
Bottom line...needs temperature-related isolation mods; Don't expect a beneficial denser (cooler)
air charge with a basic "cold air intake" system
Sure it looks cool, all chrome & stuff, and sounds cool, but a disappointment as installed.
So...Did it all work?
Actually, yes...BUT, I will set up a Dyno test later this month and report back...
That will give us real numbers to compare...
Well, yes, as Chris said, just tossing a 4.0L TB on a 2.5L manifold does nothing except lighten one's wallet.
In my thread, I described the mods that were necessary to complete the job...But I am re-threading (?!)
to clarify my process.
As an aside...the $$$ is high, and while my 4-popper was running fine
(although I did add Banks headers early on), I put off the mods until I needed a rebuild
(AFTER 168,000 MILES!)...then the $$ becomes more rational, considering the $$ of the overhaul, the extras are a smaller increase percentage of the $$ outlay
That was my chance...So, my plan came into effect...
My install process:
1) Ported Heads shaved 0.60" with O/Sized Valves.
CAUTION...The supplier of the shaved & ported & o/size valve
heads included unsuitable valve springs installed...
Stock springs are 140 lb max at TDC
Theirs were 140lb TO OPEN!
needless to say, my lifters & pushrods were destroyed.
And they claim it was my fault for not "soaking" the lifters?
Bull...just take a look at the resulting TDC spring pressure, for pete's sake!
btw...not the first time I did an overhaul...that excuse was B.S.
That being said, the heads were beautiful!
2) Hog out the opening to match the 4.0L TB (I bored mine to match the Gasket @ 62mm)
3) Four-hole injectors (from a Ford Bronco).
(4-hole gives finer atomization of the fuel, and, yes, although the ECU keeps the
Fuel/Air ratio at optimum (after the fact), the better automization means more vapourization,
which means more complete burning within the cycle (I got better gas mileage).
4) AeF Headers to replace the cracked ( poor things, after 6 years of service in our Cold Canadian Winters,
90 miles north of Fargo, Minn) Banks Headers. (They were on sale)...
5) Yella Terra Rockers...(every bit helps, besides, this was a "candy" purchase that I wanted, so there!)
6) "Cold Air" Intake...It looks good, but there are problems...
It ain't cold air!...even with putting silver reflective tape on the blocking panel side facing the Engine,
in hopes of reflecting some of the heat.
I measured (contact mount Type T Thermocouple ) the temperature of the intake pipe half-way, and found
that the temperatures were only a few (ignorable) degrees from the MIT Sensor...
Bottom line...needs temperature-related isolation mods; Don't expect a beneficial denser (cooler)
air charge with a basic "cold air intake" system
Sure it looks cool, all chrome & stuff, and sounds cool, but a disappointment as installed.
So...Did it all work?
Actually, yes...BUT, I will set up a Dyno test later this month and report back...
That will give us real numbers to compare...
I am looking forward to seeing what your numbers are. Too bad you do not have before numbers.
I bought my jeep to tinker with it. I personally do not want to do a full blown V8 motor swap. I like driving it to much to keep it down for a few months. So to me, if you get more out of the angry squirrel, more power to you but keep us posted please!
I just want to keep up with traffic, up hill, with the A/C on, LOL. I am not that far away from it.
I bought my jeep to tinker with it. I personally do not want to do a full blown V8 motor swap. I like driving it to much to keep it down for a few months. So to me, if you get more out of the angry squirrel, more power to you but keep us posted please!
I just want to keep up with traffic, up hill, with the A/C on, LOL. I am not that far away from it.
