what makes the 4.0 to be considered "high output"?
06-16-2012, 05:01 PM
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what makes the 4.0 to be considered "high output"?
I've got a 1988 xj with the 4.0, but it's not the HO. I've been considering just building it up, but not quite sure what the differences are in parts. I've heard just bigger injectors and a new fuel rail. Anything else?
06-16-2012, 06:19 PM
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Year: 92
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Engine: 4.0
Originally Posted by Greddy777
I've got a 1988 xj with the 4.0, but it's not the HO. I've been considering just building it up, but not quite sure what the differences are in parts. I've heard just bigger injectors and a new fuel rail. Anything else?
06-16-2012, 10:50 PM
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Year: 1990
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HO has different intake ports which help it make a whole 8 more horsepower at higher RPM. Along with that, the HO has a better exhaust manifold which helps with higher RPM power. Add to that the HO has a 58mm throttle body compared to the Renix's 52mm throttle body which contributes to the whopping 8 horsepower gain.
That said, the HO has no more torque than the Renix. You can get a 60mm throttle body from www.strokedjeep.com and be bigger than an HO. Add a header or just eliminate the "crush" in your exhaust downpipe and you're right there. the HO is not magic by any means and was pretty much a marketing ploy by Chrysler.
That said, the HO has no more torque than the Renix. You can get a 60mm throttle body from www.strokedjeep.com and be bigger than an HO. Add a header or just eliminate the "crush" in your exhaust downpipe and you're right there. the HO is not magic by any means and was pretty much a marketing ploy by Chrysler.
06-16-2012, 11:51 PM
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HO has different intake ports which help it make a whole 8 more horsepower at higher RPM. Along with that, the HO has a better exhaust manifold which helps with higher RPM power. Add to that the HO has a 58mm throttle body compared to the Renix's 52mm throttle body which contributes to the whopping 8 horsepower gain.
That said, the HO has no more torque than the Renix. You can get a 60mm throttle body from www.strokedjeep.com and be bigger than an HO. Add a header or just eliminate the "crush" in your exhaust downpipe and you're right there. the HO is not magic by any means and was pretty much a marketing ploy by Chrysler.
That said, the HO has no more torque than the Renix. You can get a 60mm throttle body from www.strokedjeep.com and be bigger than an HO. Add a header or just eliminate the "crush" in your exhaust downpipe and you're right there. the HO is not magic by any means and was pretty much a marketing ploy by Chrysler.
06-17-2012, 12:15 AM
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Originally Posted by cruiser54
HO has different intake ports which help it make a whole 8 more horsepower at higher RPM. Along with that, the HO has a better exhaust manifold which helps with higher RPM power. Add to that the HO has a 58mm throttle body compared to the Renix's 52mm throttle body which contributes to the whopping 8 horsepower gain.
That said, the HO has no more torque than the Renix. You can get a 60mm throttle body from www.strokedjeep.com and be bigger than an HO. Add a header or just eliminate the "crush" in your exhaust downpipe and you're right there. the HO is not magic by any means and was pretty much a marketing ploy by Chrysler.
That said, the HO has no more torque than the Renix. You can get a 60mm throttle body from www.strokedjeep.com and be bigger than an HO. Add a header or just eliminate the "crush" in your exhaust downpipe and you're right there. the HO is not magic by any means and was pretty much a marketing ploy by Chrysler.
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06-17-2012, 07:03 AM
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06-17-2012, 01:52 PM
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Year: 1999
Model: Cherokee
Engine: 4.0L
The 1987 RENIX 4.0 made 173 hp (129 kW) and 220 lb·ft (300 N·m). In 1988, the 4.0 received higher flowing fuel injectors, raising output to 177 hp (132 kW) and 224 lb·ft (304 N·m)
In 1991, a Chrysler fuel injection system replaced the RENIX system, and the intake ports were raised approximately .125 in (3.2 mm) for a better entry radius. Chrysler also enlarged the throttle body and redesigned the intake and exhaust manifolds for more efficiency, and the fuel injectors were once again replaced with higher flowing units. Camshaft timing was also changed. The net result was an engine that made 190 hp (140 kW) and 225 lb·ft (305 N·m).
Output:
1987-90: 177 hp (132 kW) at 4500 rpm with 224 lb·ft (304 N·m) at 2500 rpm. 1991-95: 190 hp (142 kW) at 4750 rpm with 225 lb·ft (305 N·m) at 4000 rpm. 1996-01: 190 hp (142 kW) at 4600 rpm with 225 lb·ft (305 N·m) at 3000 rpm. 2001-06: 190 hp (142 kW) at 4600 rpm with 235 lb·ft (319 N·m) at 3200 rpm
In 1991, a Chrysler fuel injection system replaced the RENIX system, and the intake ports were raised approximately .125 in (3.2 mm) for a better entry radius. Chrysler also enlarged the throttle body and redesigned the intake and exhaust manifolds for more efficiency, and the fuel injectors were once again replaced with higher flowing units. Camshaft timing was also changed. The net result was an engine that made 190 hp (140 kW) and 225 lb·ft (305 N·m).
Output:
1987-90: 177 hp (132 kW) at 4500 rpm with 224 lb·ft (304 N·m) at 2500 rpm. 1991-95: 190 hp (142 kW) at 4750 rpm with 225 lb·ft (305 N·m) at 4000 rpm. 1996-01: 190 hp (142 kW) at 4600 rpm with 225 lb·ft (305 N·m) at 3000 rpm. 2001-06: 190 hp (142 kW) at 4600 rpm with 235 lb·ft (319 N·m) at 3200 rpm
06-17-2012, 02:14 PM
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Year: 1990
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1987 was 173, 88 was 177, 89 and 90 were 182.
Difference in power was ECU programming.
Difference in power was ECU programming.
06-22-2012, 02:44 AM
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Well the 91-96 HO motors (stock) put out the most horse power over any other motor, by 13-17 more horse power and 1-5 more FPT. IMO any kind of free power gain is a good thing.
http://en.wikipedia.org/wiki/Jeep_Cherokee_(XJ)
Lets face it, the newer the motor the better the technologies. I do understand that there are issues when they changed things, like the heads and what not but,....
Lets think about it, a small block Chevy with a Carb or the same with fuel injection. Which would you take? Now a person that thinks power is all you need and the abillity to tune would say carb. However a person with some sort of common sence would say fuel injection because you can get power as well as economy out of it. Fuel injection triumphs everytime.
Now I dont have a Renix system and am not sure if tuning capabilitys are higher but I will say that indubitaly a stock HO system is better.
06-22-2012, 04:54 AM
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Year: 1990
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Originally Posted by Outlaw Star
Well said! H.O.: Highly Overrated. Nothing wrong with a Renix at all.
06-22-2012, 08:05 AM
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Originally Posted by ColoradoCorey
Well the 91-96 HO motors (stock) put out the most horse power over any other motor, by 13-17 more horse power and 1-5 more FPT. IMO any kind of free power gain is a good thing.
http://en.wikipedia.org/wiki/Jeep_Cherokee_(XJ)
Lets face it, the newer the motor the better the technologies. I do understand that there are issues when they changed things, like the heads and what not but,....
Lets think about it, a small block Chevy with a Carb or the same with fuel injection. Which would you take? Now a person that thinks power is all you need and the abillity to tune would say carb. However a person with some sort of common sence would say fuel injection because you can get power as well as economy out of it. Fuel injection triumphs everytime.
Now I dont have a Renix system and am not sure if tuning capabilitys are higher but I will say that indubitaly a stock HO system is better.
06-22-2012, 08:05 AM
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Year: 1990
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Well the 91-96 HO motors (stock) put out the most horse power over any other motor, by 13-17 more horse power and 1-5 more FPT. IMO any kind of free power gain is a good thing.
http://en.wikipedia.org/wiki/Jeep_Cherokee_(XJ)
Lets face it, the newer the motor the better the technologies. I do understand that there are issues when they changed things, like the heads and what not but,....
Lets think about it, a small block Chevy with a Carb or the same with fuel injection. Which would you take? Now a person that thinks power is all you need and the abillity to tune would say carb. However a person with some sort of common sence would say fuel injection because you can get power as well as economy out of it. Fuel injection triumphs everytime.
Now I dont have a Renix system and am not sure if tuning capabilitys are higher but I will say that indubitaly a stock HO system is better.
http://en.wikipedia.org/wiki/Jeep_Cherokee_(XJ)
Lets face it, the newer the motor the better the technologies. I do understand that there are issues when they changed things, like the heads and what not but,....
Lets think about it, a small block Chevy with a Carb or the same with fuel injection. Which would you take? Now a person that thinks power is all you need and the abillity to tune would say carb. However a person with some sort of common sence would say fuel injection because you can get power as well as economy out of it. Fuel injection triumphs everytime.
Now I dont have a Renix system and am not sure if tuning capabilitys are higher but I will say that indubitaly a stock HO system is better.
Having had both, driven both, had 13 Comanches with 4.0s, and worked as a Service Manager and Shop Forum at a Jeep dealer from 1980 to 1992, I can tell ya there's a max of 8 horsepower difference between the
Renix and HO.
The HO gained it's 8 horsepower by a combination of 3 things: improved intake ports, a 58mm throttle body versus a 52mm throttle body and a redesigned and improved header.
Take a Renix and add a true 60mm throttle body which bolts right on, an APN header or the like, and it will run as good or better than an HO.