Hi all new to the forums but have been doing research for quite a while. I have learned quite a bit through the various forums such as www.mx6.com www.probetalk.com and this very site. I would like to thank anyone that posts more info to this thread!! I will update all info to this first post to keep things simple to find. I have noticed a general trend that many of us are confused about our motors and what differences there are from year to year, j-spec ect. (I know I was!!) My goal here is to list basic specs for the three KL variations, differences between each one, and clear up common misconceptions in regards to compatibility and benefits of parts between the three. I have found all the information from the above sites and credit should be given to the above forums and their members. That includes members of this forum that add to the thread!! If any corrections or additions need to be made go ahead and let me know! I love to have accurate info and am happy to hear what others have to say.
First off there are three main variations of the KL series motors that we will be working with... the KLDE, KLG4, and KLZE respectively. They are all 2.5L DOHC V-6 with 4 valves per cylinder, and where available in the Mazda 626, Mazda MX-6, Ford Probe, and other cars not sold in the U.S. The KL series was available in 1993 all the way up to 2002 in the U.S. The KL series lived longer outside the states, when/if production quit I am not sure.
KLDE (1993-1997) U.S.
- 164 horse power with 156 ft/lb torque
- Compression ratio of 9.2:1
- 84.5 mm bore, 74.2 mm stroke
- Uses OBD-I through 1995
- 1996-1997 OBD-II
- 220cc Fuel injectors
- A common upgrade is to swap the stock intake manifold with a KLZE manifold. The DE manifold has oval intake runners while the ZE has square runners, so port matching is a must for best results. Also the ZE has no place for an EGR valve so if you live in a state with emissions testing or are annoyed by the CEL being on constantly this may not be the route for you. A good alternative would be to get a KLG4 manifold to swap. With proper porting and knife edging the gains will be about the same, but the runners are the same shape and it has an EGR valve. This makes it a simple swap.
- The DE uses a VAF which can be very restrictive compared to a MAF
- The KLDE uses a distributor cap. This has its ups and downs, but be aware that the distributor is driven by a gear with the cam shaft, so any swaps will need to have this gear. The cam shafts use whats called a Hydraulic Lash Adjuster or HLA for short. The HLA can cause many headaches with the car so be aware if you hear em tapping.
- The DE uses OBD-I and has some ECU upgrade options.
- Generally a KLDE will put out less power than a KLZE running similar components with the same amount of boost
- From what I can gather the recommended boost pressure is about 6psi, although I have heard of a daily driver pushing 15psi for about 7 months on stock internals.
- The KLDE uses better stock retainers than a KLZE
KLG4 (1998-2002) U.S.
- 170 horse power with 163 ft/lb torque
- Compression ratio of 9.5:1
- 84.6 mm bore, 74.2 mm stroke
- Uses OBD-II
- 220cc Injectors
- The KLG4 was introduced in 1998 so needless to say you won't find a stock MX-6 or Probe with one in it.
- The G4 uses an electronic coil pack system instead of a distributor cap.
- The G4 uses better solid lifters as opposed to the HLA system in previous models.
- The G4 uses a MAF sensor for better intake flow and more accurate readings.
- The KLG4 has the lightest crank out of the three variations (I believe about 7 lbs lighter) this reduces rotating mass...its a good thing.
- The G4 is OBD-II only
- Most parts/upgrades for the KLDE will bolt right up to the KLG4
- The power band of the G4 is shifted slightly to the right compared to the DE
- As far as I can find the ECU in the G4 is un-tweakable...
- The KLG4 can handle boost with stock internals best out of the three variations (according to members on the forums anyway) , that is it will be least likely to be damaged due to boost when compared to a DE or ZE with the same pressure under the same conditions...think apples to apples..
I want to start off by saying that there is a lack of concrete information in regards to the KLZE. With that in mind I will present the info that I have found...
- The KLZE is said to have anywhere from 190 horse power all the way up to just over 200 horse power.
- Torque is in the area of 165+ ft/lbs
- Uses more aggressive cams that allow for longer lift durations.
- Has a compression ratio of 10.0:1
- Can be put into any V6 626 with little modification (as long as you use all of your current sensors and ECU)
- Said to be best bang for buck when power is concerned
- Has NO EGR valve so to prevent a CEL the EGR should be left plugged in to vacuum lines and electrical connection...
- Mods to first generation DE ECUs can be made to take further advantage of the cams
- There are two variants available, a straight neck and a curved neck. (Straight neck is usually more spendy but better, curved necks are often used in MX-3s due to smaller engine bay)
- There are curved neck ZEs that have standard compression pistons, and standard compression cams! So be sure to get a look at the stamp on the cams if you are considering a ZE. Thanks to MonoxideChild for the info on that!
- They will produce more power with lower amounts of boost due to the higher compression ratio ( this also makes them run a higher risk of internal damage)
- An after market air intake should be used since the stock DE and G4 intake box will mount up properly. (Not sure if this is fact or fiction since I have not had a ZE)
- In a nutshell the extra power comes from higher compression pistons, different intake manifold, and more aggressive cam shafts.
- KLZE uses the same 220cc fuel injectors as the DE and G4
Intake manifold (use the best one for your application)
Transmissions (any KL, KF, K8, and KJ use the same bell housing! )
Rods pistons bearings ect...
Injectors (Millenia S or JE injectors are a good upgrade @ 280cc and a direct fit)
Some fuzzy areas that I need help clearing up:
I don't know is weather the ZE or the G4 intake manifold flows better. Seems like everyone has their own opinion with no info to back it.... I have come to the general understanding that either will flow better than the stock DE IM... so if you have any info on this lets hear it!!
I know the DE and G4 are non-interference motors. I would assume that the ZE IS an interference motor due to the flat top pistons.... but im not sure.
I can't seem to find if removing/bypassing the EGR valve will result in a power gain or not.... I know it can be done, and there are work arounds for the CEL but I just can't see why people are doing it...
From what ive read, the DE and ZE use distributors and are driven by a cam gear... so that would lead me to believe that you cant swap cams from a DE/ZE into a G4 and vice versa
Thats all I can think of right now, but if anyone has additions feel free to post em up!