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NA Mazda KL-DE (2.5L V6)

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Hi guys,

The project I initially joined HPA for is a '95 Mazda 323f (Lantis, or Astina depending on where you live) which initially had a 2.0 V6. So far, it got swapped by its previous owner with a KLDE (Mazda MX6 engine, same layout but in a 2.5L flavor and with a different intake, ecu, etc), had Mazdaspeed 6 front brakes fitted on it and was then left undone before I owned it. My goal initially was to turbocharge the engine to have a kind-of low-cost street build but after I managed to participate to amateur-level hillclimb events and discovered an amazing build on a BMW E28, I decided to go for an NA build that could race on these kind of events given the car is pretty lightweight (1.3t stock) and the engine could get good power from its displacement. This is my first project also, so please note I certainly lack knowledge and experience on the topic.

I'm starting out by working on a second engine I bought for the build so I have one I can work on and keep the car running, also I'm good having an option in case of emergency if one of them fails. For the moment what I'm doing is fitting an MS3 kit for then replacing ignition cables with VAG COPs (Audi R8 ones are around 30 bucks here so it's a good price-to-quality ratio) directly and replacing the stock ignition distributor with a handmade slot to fit a basic Bosch camshaft position sensor (Originally the ECU is triggering fire using a hall sensor at the crankshaft instead of the camshaft, but that leaves me unable to trigger the Coil-on-Plugs). Of course a custom wiring harness comes behind but I need a guess on how would you build it when it comes to replacing a stock one. I don't know if I should only patch the parts to discard the distributor connectors or replace it entirely given the wiring harness that got installed on the engine isn't quite good looking (lack of sheathing + main of my failures already was radiating heat from the engine block causing some electrical failures...).

If the custom ECU and wiring gets into place, I'm thinking of going on ITBs since people keep on praising the throttle response gain on NA preps (tbh, I would at least do it for the sound haha). I met with one of the guys at the local race events where we managed to discuss about how to feed cold air to the intake (if going on ITBs) given the engine bay heat gets quite hot, we wanted to try to make a prototype hood scoop since this is what we thought would be the solution for this but I'm no aerodynamics expert so if you guys have some experience on it, I'll gladly follow your feedbacks.

My plan after is to get the block at a machine shop to enhance oil supply through the engine. Most of the street builds I saw on this engine did just fine shimming the oil pump, but when disassembling the engine I could think of some parts where the oil flow could get improved (although this have to be doubled check at the machine shop, not that I want to weaken the engine structure...).

Once machined out, I will have to choose between 10.2:1 and 11.5:1 Wiseco pistons with forged rods. I think of 11.5:1 being okay if I think of the engine running on E85 but the stock fuel components aren't too fit for a 100% E85 build but I seek for advises over here because I completely lack experience as it's my first build. I also thought about water/meth injection as a not-too-far-in-the-future upgrade to come afterwards, but hell if I know how would I inject it on ITBs. My only two hints were I saw were this video on a BM: https://youtu.be/EyPrYBbUB3w?t=18 and Andre's post on Facebook's HPA page about the 155 DTM and the top-down injection.

This is the only points I've thought on tuning my car right about now. I think it will cost me a lot of time and money before I'll get to a full E85 map with COPs and ITB already so I didn't think anything about the "after" except for water/meth. I've added quite a few pictures attached of the project and the engine, hopefully this will come together but glad to introduce this project to you guys!

Kind Regards,


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Hello interesting build you are doing well the coils can be run in wasted spark with just the crank trigger but I would carry on and make the cam trigger to get the benefits of sequential the oiling system will need a good upgrade with a bigger well thought of pan, the factory oil pans surge pretty bad

Regards Ross

Hi Ross,

Thanks a lot for your answer! I'm still new to oil lubrication systems despite having learnt here about dry sump systems, are there other cheaper systems to consider to ensure a "good enough" flow or should I invest in a really good dry sump system ?



You can go for a fully baffled sump and possibly an oil pressure accumulator (eg moroso or accusump).

They are NOT as good as dry sump for a number of reasons, but for most people just going road/track day/drag they will usually be good enough.



I'll be taking advantage of the second block being disassembled to change the sump, this way it will get easier for me to modify it. Do you recommend having an electronic control on the oil pressure accumulator ? I don't get why you would need one atm... Thanks for the input anyway!

I once forgot to turn the accusump on. Ran the bearings. Another £3.5K rebuild. Whilst you can argue about the reliability of electric solenoids, on balance I think it would be safer to have electronic control...via the ignition switch.

It doesn't matter how good a baffled sump is, they still have limitations. Most people won't hit these and will be fine. However if you have an exceptionally fast cornering car on the wrong type of circuit you may still suffer oil surge. An oil pressure accumulator offers extra insurance.

In my case the situation was made worse by an engine design that dumped oil from the sump to the head around right hand bends, and then stopped the oil getting back down to the sump when it was up there.

One side benefit of an oil pressure accumulator, you can use it to pre oil the engine before start up. Particularly useful on a race car that sits around unstarted for months at a time.

I understand, thanks for the input again sir. I was totally unaware about the fact you could pre-oil the engine with it, I used to remove the fuel pump fuse and turn the key for some seconds for the engine to get its level of oil before starting the car.

Will definitely think about it then !

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