MADJAK's NA8 - 200+HP N/A

[speed]

Wish I could see the video but fir some reason they're not visible in tapatalk

[madjak]

looks and sounds awesome! I've never been to Collie, but that looks like crushed limestone beside the track? I imagine the dust cloud would become reasonably epic in the event of a proper 'off'

I just googled Collie lap records - 51.93 is a very good time

It's a mixture of crushed limestone and pea gravel which always ends up on the apexes. I've been off once in the wet and the mess it causes on the car is a good incentive to stay on the track.

I should be able to get into the 50s with new tyres. The guys in the outright under 2L class are doing 49s which is crazy fast but they are fully lightened race cars on slicks.

[madjak]

Sump Baffle

Earlier in the year, when running my car on the track, I noticed a severe oil dip under hard braking. Looking at my logs I was achieving over 1.25G under brakes and during the initial brake application the oil pressure would dip for a split second then come back up and possibility do it again if the brake application was long enough. My guess is that the oil in the pan sloshing forwards back and forwards again with the pickup sucking air each time.

This oil dip probably isn't that nasty under most scenarios, unless you do a mechanical over rev or blip the throttle whilst the oil is in this low pressure dip which just so happens to be how I tend to drive (preferably not the over-rev part). The response on the US forums is that this is standard with any high G braking and OEM sump and to just ignore it given that bearing failures aren't commonplace. For me, this wasn't good enough, as and dip in oil pressure due to the sump means the pickup is sucking air. This means those bubbles run through the entire system then back into the engine probably when it's at full song. I've already done a bearing in this engine at Collie when I was testing my rear wing pulling higher G's than normal. At times I'm hitting 8500 rpm which is far more than the US guys rev to and this alone puts massive loads on the big end bearings. If there are any air bubbles or loss of pressure at these points then the bearing surfaces will be seeing wear. Not only that, but I'm often hitting the brakes after sustained revs at 8500, which means there could be a very large amount of oil sitting in the head and the sump may be lower than it should be. One solution recommended was to install an Accusump, however I don't see this helping to stop the air bubbles at all, instead just keeping the oil pressure high.

There are lots of sump baffles with gated hinges etc, but my whole philosophy of keeping everything as simple as possible won out and I wend with just a simple flat aluminium plate that seals tightly on all sides and especially the front edge so that the oil is held captive. Testing last weekend showed this solution to work very well with no oil pressure dips in the logs whatsoever. When installed I put a small bead of silicon along the leading edge so that the sump is sealed. This will keep the oil captive regardless of the braking G forces.

here is my cardboard template:


and installed in the sump:



I have a CAD profile of the sump, so if anyone wants a plate cut, I can do it in my next waterjet run and post if over. Not only does it work extremely well, it's lighter than the stock baffle that it replaces! Bonus.

[madjak]

I was able to spend a few hours in the workshop tonight so I started cutting down my spare crank. It's easiest to do a rough cut with a hacksaw first to remove the bulk material and then trim down the last few mm on the mill.



The crank then gets mounted up in the mill using the main end bolt and three flywheel bolts to locate the crank on my target angle. Its held nice and firmly on the bed with some 8mm steel angles.



I'm using a big cutter which takes off the metal fairly easily. I get around 1mm off each pass do I can rip it down fairly rapidly.



The finish is pretty nice. I'll use a flapper disc to round all the edges so there is nothing sharp.



Thats basically half of the crank done. I'll do the other side next week and then take it to my father in law's workshop to lathe some small knife edges on it.

[madjak]

Still milling my crank... 4 nights so far but its nearly done. I picked up a small alternator from a suzuki wrecker for $40. Looks really good and is nice and small. Its slightly less grunt at 50 amp. It even has a 4 rib pulley... anyone needing a pulley to mount a NA6 alternator on a NA8 should visit a Suzuki wrecker as the pulley on this will bolt onto the smaller v belt alternator.



My plan is to mount it on the hot side so I can clear some space on the drivers side with the added bonus of moving some weight to the passenger side.

I'm going to be moving to a EWP and will be making a billet plate to replace the water pump. This plate will have a mount point for the alternator adjuster.

[madjak]

Crank milling is complete. That took off 1.8kg of metal mostly off the outer edges. The next stage is knife edging on a lathe which should take off another kg or so. I also pulled out the ball bearings blocking the oil journal. Man there is some bad junk behind them!

[oztrackdays]

Won't taking Mass out of the Crank reduce torque/power actually delivered from the engine.

I get that it will spin quicker and higher.

I thought the holy grail is the power band underneath the curve.

[madjak]

I'm not sure where this theory that lightened cranks / flywheels effect torque. I don't think it's true. They certainly effect driveability at low revs though and the chance of stalling.

My intake, cams etc are all designed for max power at 8000 rpm. I also run a 6-speed box with a 4.78 rear diff so my gears are close together so that rev drop between gears is minimal. If I'm below 6000 rpm it's either a warm up or cool down lap, or it's raining and I'm trying to limit torque for traction. Area under the curve means very little in that case as it's more about total power.

This whole area under the curve thing is overstated. For a street car, yes its brilliant and a good gauge of a fast car. For a race car it's the wrong metric to look at. You ideally want a flat torque curve and maximum power over the used rev range and as far up revs as possible. Everywhere else is unimportant.

The mass of the crank / flywheel / drivetrain / wheels affect the acceleration of the vehicle an order of magnitude more than static mass. That's a big generalisation but it's kind of true... except that how much the mass increase / loss affects acceleration depends on how far out it is from it's rotating mass (ie Moment of Inertia). Mass in the engine is especially important as it can be accelerating far faster than the drivetrain which is geared. So a drop of 1.8kg from a crank, it's equal to dropping 18kgish from the car in terms of straight line acceleration.

The other benefit to less crank mass is that it lets the engine drop or increase speed quicker, which helps greatly when changing gears rapidly.

[madjak]

I made a couple of 8mm ally tow hooks for the rear. They are designed for a cut bumper and lift the tow point loopup a fair bit to hide them a little. In order to fit them I need to trim the little bend flange on the back tow point mounts with a cutoff disk.



Waterjet cut then chamfered with a router. They were cheap, are nice and light and should be strong enough.

[beavis]

It's a shame you're not in Melbourne, as I'd like to know how you get small run things like this waterjet cut cheaply.
Something like that for would cost me about $50.

[madjak]

Minimum order is $80, so i waited until I had a few things to cut. I also find waterjet cutting is cheaper than CNC by a decent amount.

[madjak]

Here is a photo of the two custom tow points with the cut rear bumper:





If anyone wants one shout out and I can add it to my next CNC order.

[madjak]

Billet Fuel Rail

Since installing my Skunk2 Ultra Street intake manifold I've never like the placement of the inlet and outlet pipes on the stock fuel rail. I've been meaning on purchasing a high flow rail but they are all fairly pricey from overseas. I've also had issues with the Xspurt fuel injectors not quite sitting right with the stock rail so I figured I'd make my custom rail.



I made the holes where the stock plastic spacers sit nice and snug so that they don't fall out when installing the rail (a pet hate of mine). I kept these spacers as I think they act as an insulator to stop the fuel rail picking up heat from the head.



This is a test fit on a spare head. All works as it's supposed to. I added two 1/8npt ports up on top for a sensor or pressure gauge for when I'm dynoing. I'll blank these off with plugs for typical use.

[mx5002]

Fuel rail looks great!

[Zabinskii]

soooo, wanna make another fuel rail ;)