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I've been on this forum for a few years... so I finally thought I should start a build thread for my car. I'm going to do this a bit differently because my car isn't the standard MT.net build and plus we do things differently down here in Australia. As such I'm going to start at present and work my way backwards. There is heaps of odd and custom parts on my car, mostly made by myself so I'll try and show some of the stuff I've learned over the last few years.
What started off as a 1989 Eunos Roadster B-spec daily has evolved into a full track car. I'm currently running:
Built 1994 BP race engine - 13.5:1 compression, E85, oversized valves, ported head, skunk2 intake manifold, s90 throttle body, EWP. (approx 200whp N/A)
Drivetrain - 949 twin, 5 speed close ratio dogbox, 4.78 torsen diff
Exhaust - 4:1 custom headers, 3" straight through pipe with a Magnaflow muffler
Chassis - fully caged, AST dual adjustable shocks, 10" 6ULs with 245 Hoosiers, 3D printed rear wing, front splitter, dual master brake pedals with balance bar
Electronics - Haltech PS1000, Race Capture Pro, Nexus 7 display
Here is a video from last weekend. This was the first time I've driven with the dog box installed and beat my PB from last year by 0.6 seconds. I have just rebuilt my engine so this was 'run in' with a limited revs of around 8300 rpm instead of 8800. I'll up the revs after I've checked oil and lifter tolerances. This engine makes all of it's power from 7000-8500 so the aim is to keep it in that window for as long as possible, hence the close ratio box and 4.78 diff. At 6500 I'm down to around 170whp and 6000 150whp and at anything below 4500 the car hardly runs.
Lets start off with a few car shots. The body is fairly standard, with only a few modifications such as the full cage, flares, and a bumper cut. I've removed all the bumper supports and lightened the doors but I still run what looks like a full interior, with carpet, standard dash and center console, however it's all just a shell. I like to keep the car functional but tidy and as light as possible.
My future plans for the car is a tubular front end, flat bottom and diffuser. Other than that it will mostly stay as is.
My engine is fairly similar. It's a combination of function and need. I only run it if I have to, and it's as small as it can be.
The engine block is fairly straight forward... a 1.8 BP bored out to 84mm. I'm running a stock crank (although I have a lightened crank to go into it), Crower rods, 10.5:1 Wiseco pistons, MBSP, DIY sump baffle, Oil pump with no pressure regulator (external Peterson regulator instead), no oil squirters, and a cut down stock harmonic balancer.
The block itself has also been tidied up on the inside the promote some better oil drainage and the coolant passages internally have been grouted up to the bottom of the water pump hole. I also run a blank off plate for the EWP.
The head is where all the magic happens. In order to get big power out of a BP you basically need to shoot for high compression, big cams and allow it to breathe. By doing so you move the powerband upwards so you also need to build it for high revs. To up the compression the head has been decked around 2.5mm. This raises the compression to somewhere around 13.5:1. This amount of decking causes a few major issues, the first being to offset the timing and it makes it hard to run the required belt tension. I get around this with adjustable cam gears and my billet water pump blanking plate has the idler moved in a few mm. The second issue is that the valves become interference so you have to machine out the valve reliefs on the pistons.
I'm running high lift, high duration cams which are custom grinds. They are somewhere around the 310 duration mark with 11mm lift. This results in a massive overlap making idling atrocious, however once it hits 4500 rpm, the engine quietens down and starts to purr.
This head was first built 12 years ago before oversized valves were available and used to run stock RB26 intakes and custom exhaust valves. I have just rebuilt it due and I'm now running Supertech Nissan RB26 intake valves (approx 1.65mm oversize) and on the exhaust I'm running Supertech Mazda +1mm inconel valves. These valves are interference to each other so I need to be careful when turning the cams and setting timing not to hit the piston or the other valve.
The head itself has been professionally ported, but I've done some additional work on it too. I've cleaned out all the casting burrs, unshrouded the valves and cleaned up the combustion chamber. The valves seats have a 4 angle cut blended into the chamber and port and all the ports have all been smoothed out and opened wider with a lot of work to the short radius etc.
All up the combination of parts in the head are obviously working well. This engine is producing over 180whp from 6750 through to 8500 rpm which is impressive for the BP-05 head.
Here is my dyno a few years ago. It's been tweaked a bit more since then, upping the revs and better intake flow. (note this is power at the hubs not at the flywheel)
I'll cover some of the other bits like cooling setup, intake, exhaust next week.
Impressive work. How long do you expect it to last between rebuilds? I know the stresses must be enormous at those RPMs for a BP.
I run it for a season between rebuilds. I compete in time attack sprints so at most I would only do 500km a year at arund 10hours run time. Mostly its just to freshen up bearings and check everything but last rebuild was a complete rebuild after floating some valves at the last few events.
The main reason for the short rebuild time is to monitor the big end bearings. This engine has spun a big end bearing around 18 months ago when I was running the car with the 3D printed rear wing for the first time and it developed an audible whine. Pulling into the pits 1/3rd of a lap later and it was obvious a bearing had gone. This was the damage:
I believe the issue with high RPM engines on the track is that the oil accumulates up in the head and you loose a lot of oil volume in the sump. If you are braking at high G's the oil moves forwards away from the pickup to the front of the pan and the pickup takes a couple of gulps of air. This air then travels through the oil lines and hits the block right when you are back on full power. In my logs I could see two dips in oil pressure under hard braking that I think represents that 'slosh'. Adding the sump baffle has fixed that oil dip even when hitting over 2G's under brakes. I also run a bit more oil in the sump.
On the last build, after adding the sump baffle the bearings still looked great so I think the issue is now resolved.
I've been thinking of dry sumping the engine at some point which will fix any oiling issue and pull a vacuum on the crankcase. I could make my own billet sump easy enough and I was thinking I could even add an integrated crank girdle. That might be a project for later this year.
Accusump only masks the issue though. If the pickup is sucking air, there is immediate loss of pressure in the oiling system which the accusump would fix, but this pressure loss is right when you are braking and not under load. The issue I see is when that air travels through the oil cooler and lines and then hits the engine 3-4 seconds later when the engine is on full song.
If an oil pickup on a track car is sucking air it's always a bad bad thing.
Thats only on the back... I don't actually need them and don't run them on short trips, but only longer trips on bumpy roads I like them to hold the back of the car from skipping side to side. The front wheels are strapped down to the trailer with ****** straps over and around the wheel.
I run an extra quart on the track to help allay starvation and hopefully add some thermal capacity to the oil. You said you are running more oil too. I know it reduces the crankcase air volume and can probably increase windage and blowby. Have you seen evidence of this in your experience? I haven't but mine's not spinning as fast as yours.
I run an extra quart on the track to help allay starvation and hopefully add some thermal capacity to the oil. You said you are running more oil too. I know it reduces the crankcase air volume and can probably increase windage and blowby. Have you seen evidence of this in your experience? I haven't but mine's not spinning as fast as yours.
Last time I had the sump off I meant to measure and mark on the dipstick where the bottom of the MBSP sits but I forgot about it. My oil level sits around 4-5mm obove the full line but I think that is still below the MBSP.
When on track I haven't noticed any performance difference but I think the extra oil just is sitting up in the head when I'mI'm pushing hard. I am finding it harder to start and before my last rebuild I was getting more blowby but that could be lots of different things.
Accusump only masks the issue though. If the pickup is sucking air, there is immediate loss of pressure in the oiling system which the accusump would fix, but this pressure loss is right when you are braking and not under load. The issue I see is when that air travels through the oil cooler and lines and then hits the engine 3-4 seconds later when the engine is on full song.
If an oil pickup on a track car is sucking air it's always a bad bad thing.
I have an accusump on my car, but no data or lap times to quantify it helping anything (but lots of high RPM, high power usage and no bottom end failure in 2 years so far). I will say it's heavy, and I think on my next motor I'm going to focus on getting the oil to flow back to the block better and a better sump baffling. That would be a lighter and simpler solution, the accusump was expensive and heavy when filled with oil and plumbed into the engine. Although starting the car with oil pressure every time is pretty sweet. Maybe do an electric oil priming pump, as that is easy and cheap and weighs maybe 1 lb. The accusump is probably 15lb for comparison.
I don't like the extra complexity and weight of the accusump and I don't like adding moving parts that can fail.... I currently don't run a thermostat or oil squirters for the same reasons. It would be nice to be able to pressurise the system when cold cranking the engine, but other than that I don't think it really helps the main issue of sucking air into the oil. My only real issue now is the risk of a factory oil pump gear blowing itself to smithereens... In Australia there are lots of MX5 racecars running external Peterson oil pressure relief valves. It's a practice that started with a few top engine builders and has been adopted by others. Not only does it give far better oil pressure control, but it supposedly stops the chattering and backpressure within the oil pump at high revs which is the reason for the shattering of the gears.
Just because I like to experiment I was thinking of building a DIY dry sump setup. What I'd would be a two part billet sump, the first section would replace the MBSP and would bolt to the block and pickup the main bearing caps. I'm not sure if 6061 would be high enough grade, but it depends on how thick that bridge over the main caps. I could embed a 4140 flat plate to act as the bridge too if I think it needs more strength. Then there would be a bottom plate that has two oil pickups in the center for the dry sump scavenging. I'd run inline filters into the dry sump pump then off to a oil swirl pot. I'd also have to make a front plate to blank off and seal the crank and I could also scavenge directly from the head too. My issues with it is that it adds more plumbing and belts which goes against my own design criteria of keeping it simple. Overall it would be a bit of an undertaking but it satisfies my needs to engineer stuff and might even net me a bit more power by pulling a vacuum on the crank case.
I have considered building a similar piece to tie the bottom together, but I would personally use steel if I built one. Steel would be stiffer, stronger, and expand/contract more similar to the block vs aluminum.
I don't run a drysump for the reasons you mention, it's a lot of stuff and a belt failure or loose fitting could be really bad. I drive my car on the street so put more hours/miles on a motor which could lead to a failure from use. On the oil pump, yeah only for use for startup, it would do pretty much nothing compared to the main oil pump once running.
The harmonic damper on my engine is looking a bit damaged with the rubber starting to show some cracks. Its done some hard work and is now over 20 years old.
I have cut down a spare stock damper to the same sizing as the one on the engine. Basically I just mounted it in the lathe squared it up with a dial gauge and sliced off the outer pulley with a cuttoff disc. I then smoothed the cut surface with a flapper wheel. Its hard to lathe as the outer ring is mounted on rubber so it will chatter when cutting. It's also hardened so its tough to get through in the first place.
So I was looking at an old oil pump. And figured this would be the best place to post. Because I don't remember where else we talked about the external bypass valve.
But this is the outlet of the oil pump to the block. And right behind it is a threaded plug. Couldn't you theoretically put an adapter fitting in that threaded plug, run it to the external pressure valve, and then dump back to the pan?
Would that achieve the same result as adding it inline somewhere?
So I was looking at an old oil pump. And figured this would be the best place to post. Because I don't remember where else we talked about the external bypass valve.
But this is the outlet of the oil pump to the block. And right behind it is a threaded plug. Couldn't you theoretically put an adapter fitting in that threaded plug, run it to the external pressure valve, and then dump back to the pan?
Would that achieve the same result as adding it inline somewhere?
The external Peterson valves we all use take a high pressure feed from the engine and split it off into a oil feed at the required pressure and then the excess is diverted back to the sump. Given you need to feed it back in to the block anyway you may as well use a standard sandwich plate to pick up the in and out from the engine in one place.
I suppose you could take the feed directly from the pump via that threaded hole too. It might even be better as there is probably less resistance running through a single line than routing through the block to the stock filter location and then through an AN line. Not that resistance on the high pressure line is an issue but it might make the pump less stressed.
Here are some pics of my solid engine brace. Not so easy for you FI guys to fit but I have heaps of room on this side of the bay. My engine moves around a lot even with the erothane engine mounts and I don't have massive clearance between the chassis rail and the TPS.
A solid mount helps also massively with shifting accuracies which is critical for me now I'm running a dog box. One missed shift from the stock 2nd to 5th gear will be 3rd to 1st due to the dog box gear locations. This would be disasterous as there is no clutch and the dogs will be in.
The issues with doing this is the transfer of all engine vibration to the chassis. I've had a few things vibrate off my car including the clutch master cap, my tps and parts of my dash. I'm going to start loctiting everything.
The aluminum tube is very light because there is not much left. I've drilled and tapped each end then flattened and slotted the rest. Of course the grams I've saved are totally outweighted by the heavy oversided rod ends but it was fun machining it and it adds some bling to the engine bay.
I need to make a nicer bracket to bolt it to the engine.
03-20-2017, 04:58 AM
MadJak's Not-so-stock NA6
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