Starting a thread to record progress on my build and to help anyone trying to also do a big turbo build in the future. I am starting from essentially a stock car with the goal to eventually make somewhere in the 500whp range which was initially never my intention. My 2008 MCS was killed when the vacuum pump seized up coming off the highway resulting in the cam sprocket bolt being sheared off the exhaust camshaft and dropping its timing chain into the engine while it was running. After I let the car sit for a while I had to decide between getting rid of it or fixing it so I pulled the engine to see how bad the damage was, luckily there was no damage to any pistons or the cylinder walls and only two bent valves. I opted to get a new head for the car from a junkyard to be on the safe side and provide some spare parts for the future just in case any of the valve guides had been damaged. Since I had the motor out and the head off I decided to clean it up and replace some valve seals and upgrade to supertech springs. I then also decided I might as well throw in some forged rods and pistons in case in the future I wanted to run a hybrid turbo. Somehow I fell down the rabbit hole of "while I'm in there" and ended up with a CSS'd block, CP 9.5:1 pistons, K1 rods, a ported head, Supertech valve springs, ARP main and head studs, and a bunch of other goodies. At that point putting a hybrid turbo on the car just didn't make sense and so I've begun the process of making up a manifold myself to run a larger Borg Warner turbo as well as cobbling together a pretty serious meth injection system since the HPFP is so limited. I'm still acquiring parts and have a lot to go still so this won't be the fastest build since I'm basically starting from scratch and have been using the lessons learned by other members to hopefully put together a very solid engine and make as few mistakes as possible. Also doing this all in my driveway and need the weather to get a little warmer up here in the north east, but the goal is to have the motor back in by the summer.

 

This is exciting.

 

Before selecting the turbo, be sure you understand how the "A/R" rating affects performance. Since "turbo lag" usually gets worse as turbo wheel size increases, performance increase will also shift towards higher RPM's, making the choice of A/R even more important. You need to decide where in the RPM range you want the turbo to be most effective, and select the A/R accordingly. Most big turbo manufacturers have good explanations on the different characteristics, just gotta root around their web site to find them.

Have fun with a manifold design --- choice of material and turbo location are probably the most critical factors. There's not a lot of working space either. Sounds like you're on the right track --- learn from the mistakes of others. Keep us posted ---

 

I’ve built some other turbocharged engines in the past (mainly Honda’s) so I have a good grasp on all the lingo and what the A/R means for them. Since there’s not a ton of information out there or lots of big turbo mini builds I will most likely purchase two exhaust housings with different A/Rs that I think will work and try them both in the dyno to see what works best. I’ll most likely go with a 0.83 and something close to a .63 to see if the smaller housing still has enough flow, I feel that with our low rev limit due to the oil pump the smaller will work best. As for the manifold my plan is to use some 304 stainless 1.25” tubing to keep the exhaust velocity high and get the turbo spooled as early as possible. I have some ideas/tricks I’d like to try as well for this car to see what works once I start getting it tuned. On a side note I haven’t yet started the exhaust either and was hoping to squeeze in some 3.5” tubing, do you think this is a possibility? AC system has obviously been scrapped already to make room.

 

I’ve been looking at BMW N54 high pressure fuel pumps as they are extremely similar to the Mini N14 HPFPs. Finally decided to take the plunge and bought one to pull apart to see if it could be made to work and measured it in comparison to the stock N14 pump. Internally the two pumps seem almost identical with the BMW pump having one additional bellow/piston combo and all of which are the same size as the N14. From what I have found online these BMW pumps are good for somewhere around 400whp on E30 give or take a bit and spin roughly 1/3 of the crankshaft speed. Going off the camshaft would get it spinning at half the speed of the engine and would yield a little more flow out of it with it being a positive displacement pump, spinning it a little faster is not a concern since the BMW folks are over driving these with planetary gear sets to 3-4 times the orginal speed.

Comparing the dimensions of the pumps the part that interfaces with the camshaft is identical in shape and size with the main differences being that the N14 pumps stack up height is about 2mm more than the N54 pump. Sitting the N54 pump flush in the head and it makes good contact with the camshaft however it does not sit as deep. I was hoping to machine the face down and create a bracket however after pulling it apart the housing is not thick enough to take off 2mm. In tearing it apart I realized that the piece that interfaces with the intake camshaft can just be unscrewed so I’ve designed up a new one in CAD that will be 2mm taller to mate better with the camshaft. I’ll also make up a bracket to adapt it to the head which should be fairly simple and straight forward.

The temperature compensator and control solenoid are identical to the stock N14 pump and can be swapped around so I’m confident the ECU will be able to operate the N54 pumps solenoid. I’ve managed to source an adapter for the low pressure feed side of the N54 pump from the UK to convert it from the unusual M14x1.50 metric 60 degree tube to a 5/16 quick connect that the stock feed line uses (although I may change the whole line from the pump to a -8AN). I’m fortunate to have a great local company that can make any custom lines you could think of that will make a short hose to adapt the N54 pump to the mini fuel rail. Just need to get some quotes for machining the camshaft interface and source another good N54 HPFP and hopefully I’ll have a good solution to our lacking HPFP.



Comparison of the back of the pumps, N14 on the right and N54 on the left



N54 fuel pump from the side showing it’s interface to the N54 vacuum pump which is the same design as the N14

N14 HPFP camshaft interface

Internals of the two pumps, N14 on the left and N54 on the right

 

I like learning more about these little cars, and I’m interested to see if you can get that fuel pump working