• Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

differences between normal 4.0 and high output 4.0

the major one is the engine control system, the H.O. head is differant, the ports are slightly differant, tb is differant, coolant system is differant. fuel system is differant at the fuel rail... etc etc...

its differant. but not tooo differant. whatcha got in mind?
 
xcm said:
the major one is the engine control system, the H.O. head is differant, the ports are slightly differant, tb is differant, coolant system is differant. fuel system is differant at the fuel rail... etc etc...

its differant. but not tooo differant. whatcha got in mind?
Click to expand...

87-90 4.0 with Renix (Renault-Bendix) engine management.

91-01 are H.O. engines--HP was increased, cam was changed, pretty much everything xcm posted above.

However, the closed cooling system for the 4.0 was 87-91, and the fuel rail was essentially the same 87-95, 96 a bastard year, 97-01 essentially the same, so these two system aren't quite a Renix/H.O. differences.
 
blazinjames said:
I currently drive a 95 XJ and Im planning on buying a engine to rebuild im just wondering if I need to buy a highout put engine or just a regular one
Click to expand...

any 91-95 will bolt in without swappin any sensors, a 96-99 would work except theres no 2nd coolant senso on the back on the head, and all sensores will have to be swapped over aswell as dist. and coil
 
joe_peters said:
the fuel rail was essentially the same 87-95, 96 a bastard year, 97-01 essentially the same, so these two system aren't quite a Renix/H.O. differences.
Click to expand...

i beg to differ, my 1990 xj has a differant fuel rail than a 92 mj... injectors are also slightly differant... maybe they do the same thing theoretically, but the parts arent the same...
 
I just put a ho 4.0 from a 94 grand cherokee in my 89 renix. And it was my first motor swap, and I was amazed at how easy it was. So don't worry about swapping a few sensors, its easy. Good luck.
 
joe_peters said:
87-90 4.0 with Renix (Renault-Bendix) engine management.

91-01 are H.O. engines--HP was increased, cam was changed, pretty much everything xcm posted above.

However, the closed cooling system for the 4.0 was 87-91, and the fuel rail was essentially the same 87-95, 96 a bastard year, 97-01 essentially the same, so these two system aren't quite a Renix/H.O. differences.
Click to expand...
Not sure, maybe closed cooling system was a mid year split, but my 91 has an open cooling system and was completely stock when I bought it.

ROBZ95Xj said:
any 91-95 will bolt in without swappin any sensors, a 96-99 would work except theres no 2nd coolant senso on the back on the head, and all sensores will have to be swapped over aswell as dist. and coil
Click to expand...
I *think* my 96 has a second CTS on the back of the head, will have to check. Would look at my FSM but I was an idiot and put it in my storage unit when I moved :(
 
joe_peters said:
However, the closed cooling system for the 4.0 was 87-91, and the fuel rail was essentially the same 87-95, 96 a bastard year, 97-01 essentially the same, so these two system aren't quite a Renix/H.O. differences.
Click to expand...

Incorrect, the closed cooling system ended in 1990, not '91.
 
xcm said:
i beg to differ, my 1990 xj has a differant fuel rail than a 92 mj... injectors are also slightly differant... maybe they do the same thing theoretically, but the parts arent the same...
Click to expand...

Ill agree.

Renix had the pressure line enter at the front of the rail, and return was at the rear of the rail.

91-95 had the same fuel line, both pressure and return were at the front of the rail.

96+ was single, returnless line.
 
Yep... heat soak / vapor lock.

Very rare to have it be an issue on anything except a 2000 or a 2001 though, due to the pre-cats added just below the manifold and injectors (this can be solved by adding a timer that keeps the e-fan on for a few minutes after you shut the vehicle down.) It does pop up occasionally on older XJs though.

Oh and the fuel pressure regulator is either inside the tank (96) or on top of the tank (97+) with the returnless system.
 
kastein said:
Yep... heat soak / vapor lock.

Very rare to have it be an issue on anything except a 2000 or a 2001 though, due to the pre-cats added just below the manifold and injectors (this can be solved by adding a timer that keeps the e-fan on for a few minutes after you shut the vehicle down.) It does pop up occasionally on older XJs though.

Oh and the fuel pressure regulator is either inside the tank (96) or on top of the tank (97+) with the returnless system.
Click to expand...

I wouldn't consider that a huge downside. Sucks when it does happen, but it doesn't hurt anything. Chrysler has a sleeve you put on the fuel line to help prevent this problem.
 
xcm said:
i beg to differ, my 1990 xj has a differant fuel rail than a 92 mj... injectors are also slightly differant... maybe they do the same thing theoretically, but the parts arent the same...
Click to expand...

Yes, the parts are not the same, they are essentially the same as in pressure regulator on the rail, with a vacuum port, pressures are 31 with vacuum, 39 without vacuum, fuel return line from the regulator to the fuel tank, and the rails can be swapped between a Renix and a 91-95 H.O., takes barbed fittings, hose clamps, and rubber FI fuel line, less than $15 in parts, and the injectors are 19 psi and can be swapped, but why anyone would want to use older injectors on a newer engine I don't know. As I posted, essentially the same and not a Renix/91-95 H.O. major change.
 
kastein said:
Not sure, maybe closed cooling system was a mid year split, but my 91 has an open cooling system and was completely stock when I bought it.
Click to expand...

I believe you are correct, part year changeover, but I can't access my parts catalogs (main notebook is down), anyway, If my memory hasn't left me completely to make sure you got an open-system radiator for a 91 you were better off ordering for a 92+ XJ.
 
kastein said:
Yep... heat soak / vapor lock.

Very rare to have it be an issue on anything except a 2000 or a 2001 though, due to the pre-cats added just below the manifold and injectors (this can be solved by adding a timer that keeps the e-fan on for a few minutes after you shut the vehicle down.) It does pop up occasionally on older XJs though.

Oh and the fuel pressure regulator is either inside the tank (96) or on top of the tank (97+) with the returnless system.
Click to expand...

The TSB on heat soak actually covers all 4.0s 99-04, it was/is that much of a problem.
 
You must log in or register to reply here.

Similar threads

S
All D30 lockers the same?
Replies
9
Views
471
RCP Phx
R
4
Timing gear?
Replies
3
Views
101
4x4JeePmaNthINg
4
Z
RENIX fuel delivery questions
Replies
4
Views
338
Ecomike
Ecomike
F
Up to '98, '99-'00, & '01 Alternators; Differences
Replies
1
Views
1K
75SV1
7
XJJeeper59
99 XJ ECU Swap Question?
Replies
2
Views
2K
XJJeeper59
XJJeeper59
Back
Top