Join Date: Dec 2010
Location: Nashua NH
My Ride: Broken dreams
Engine: An odd mix of 2.2 and 2.5 engines.
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Feedback wanted on a mild 2.5 build
So on the latest chapter of the longest ever 24 hours of lemons build, I'm finally thinking about the engine build. In my garage I have a common block 2.5 turbo I from a 1989 spirit that I'm using as the engine for the BMW project. I would like to build it up slightly so it's making around 200-225hp, but still be reliable. I'm trying to figure out what parts I absolutely should upgrade, and which I can leave alone to get there. I don't want much more power than that because endurance racing is hell on modified engines, and honestly 225hp in an E36 is probably just fine for what we're doing.
Important things about our goals. Endurance racing is crazy hard on engines. We are WOT a lot, for 7.5 - 9.5 hours at a time with only fuel stops as breaks. Heat management and oiling are king. We do not need crazy power, we need safe power that won't be on the ragged edge of failure. I just would like a mild bump from the stock engine.
I wasn't going to change much inside the engine. I know fancy forged pistons are nice, but I was hoping that the regular ones would be ok for such a mild increase. If this is just wishful thinking, let me know, I'll change some budget around.
I do have a bunch of TII rods kicking around, so I can upgrade those.
I will be getting the block and head decked to make sure they're in spec for a cometic MLS head gasket as well as hone the cylinders if needed, and I do have ARP head studs for the engine. It'll get new bearings while it's apart.
Balance shafts are already out and oiling hole plugged.
I have the higher flow oil pump to put in the engine that'd used in previous engines, and I have a large oil cooler off of an FC RX7. No other real changes to the system other than a stainless feed line to the turbo. We tend to run 5W-40 in the race cars.
I'll be using the largest radiator I can stuff into the E36 with a good fan setup. I'll use whatever water pump makes the most sense for my modified belt routing (I have to move the alternator to clear frame rails, it's going roughly where the power steering pump should be with a TON of heat shielding), I have an early and later reverse rotation pump. I have the pieces already for the cylinder 4 mod, which has helped in the past, and I'll be using a 180° thermostat. I do want to upgrade the system to a more modern expansion tank setup, rather than the older overflow design, I just like it better. I think some of the E36 radiators have that built in.
We use a fuel cell with walbro in line pump. I was going to get an adjustable regulator to be safe. All the injectors I have are the TII injectors. not sure yet if these need to be upgraded for the mild power bump.
I've cut open my single piece intake, cut out the runners a bunch, and welded it back up. The throttle body is moving to the other side to make intercooler piping easier when it's in a RWD setup. I was going to upgrade to the V6 throttle body however. The turbo inlet I'll plumb to fresh air somehow with a cone filter.
Not much changing. I might port match the manifold if I feel bored, otherwise 2.5" downpipe and then straight pipe out the back. If I get really bored, I might make my own manifold simply so I can mount the turbo backwards and have the cold side face the front of the motor, it would make pipe routing easier. But that is likely a down the road project.
I have about 4 stock garret turbos sitting with various levels of wear from mostly fine to the nut fell off the cold side and everything is dead. I plan on rebuilding the best one and using that. I would like to keep turbo boost ECU controlled if possible, but I can run a manual controller if needed.
I have an SMEC from my old '89 daytona that's been modded to have the flashable chip in it. I will be adding a wideband and upgrading the MAP sensor and updating the tune to match.
Looking for input on the above for things I should do differently or which parts are good, in order to get to that safe 200-225hp number.
2.2 Turbo RWD Lemons project