MADJAK's NA8 - 200+HP N/A

madjak · Postby **madjak** » Wed Sep 30, 2015 9:07 pm

Can I just unplug it to test? Does it add any internal resistance?

Magpie · Postby **Magpie** » Wed Sep 30, 2015 9:18 pm

Yes provided the booster is vented to atmosphere.

Ice88 · Postby **Ice88** » Thu Oct 01, 2015 9:33 am

What's your target idle? Could always increase it to create a more stable vacuum

sailaholic · Postby **sailaholic** » Thu Oct 01, 2015 9:34 am

Just remove the line from the booster to your manifold and block the manifold end. That will be the same as a booster delete.

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madjak · Postby **madjak** » Tue Oct 06, 2015 5:43 pm

This isn't what I was planning:

The damage isn't that bad with only very minor scoring to the crank and rod. There is a heated area on the rod which I'm a bit concerned about but the machine shop will have a look at it. It looks like the bearing spun initially, jammed up and then got hammered by the rod. The bottom bearing looks ok except it's been flattened and widened, whilst the top has been hammered so much that the bearing is being forced out of the sides of the rod.

I did a nice quick lap during practice whilst testing my 3D printed wing and no brake booster. It was 2 seconds quicker than my previous best time which on a 50 second track is fairly impressive. When I backed off I felt some resistance in the engine and a heard slight whine, and by the time I slowed down and pulled into the pits I could hear a tick. Stupid thing is that the TPS had died earlier in the day, the little screw holding on the to lever to trigger the TPS broke off. My engine logging is triggered by the TPS so i have no logs of the run that caused the problem, so I have no idea of it was oil pressure or not that caused the issue.

Initially we weren't sure if it was a bearing or not, as the tick sounded like it was coming from the head. I thought I'd bent a valve or something so we ran the engine in the pits to try and determine the issue. Probably made the bearing a bit worse but it wouldn't have gotten hot at least.

The crank and rods have been sent off to be checked and machined. I'll strip the entire engine and do the complete rebuilt I was planning next month. Now I just need to source some ACL bearings of the right size so I can get it all back together for the Nationals.

In terms of braking, running boosterless was much better. The load I had to apply initially to the brakes was definitely increased but the feel and linearity of the brakes was very much improved. With the booster it's like you get a high initial bite, and then have to push hard to get past the first hump. Without the booster it felt far more consistent with a more linear relationship between pedal pressure and braking. I will be removing the booster whilst the engine is out of the car.

The rear wing balanced out the car beautifully. I could hit the the big left and right sweepers at a much higher speed with the car feeling much more stable through the corner. The wing wobbles a little so I'll have to make up some stronger supports.

As a whole, I'm much happier with the car's performance, but of course spinning a bearing and sitting out of a weekend's racing was a bummer. At least I get to play with the insides of the engine, and maybe tidy up my engine bay a little.

Magpie · Postby **Magpie** » Tue Oct 06, 2015 6:07 pm

Sad news, but it was not a catastrophic failure. Good luck with the rebuild.

madjak · Postby **madjak** » Wed Oct 07, 2015 2:13 pm

Unfortunately the machine shop says the crank requires a grind... problem is it's already at 0.5 bearings. I have a spare crank but it also has done a big end. I'd prefer to work up a new stock crank that hasn't already been machined so PM me if you know where one is!

zossy1 · Postby **zossy1** » Wed Oct 07, 2015 3:12 pm

Bugger.

How many hours on the engine?

madjak · Postby **madjak** » Wed Oct 07, 2015 5:43 pm

I picked this engine up second hand from QLD, so I'm not sure on the hours it had done previously. I know it was run at Bathurst which would have been pretty hard on it and then had been sitting around for a few years. Myself I've done approx 20 hours maximum.

Looking at the logs and the failure, I suspect a few issues may have reduced the bearing life. When I first installed the engine it took a while to get oil pressure. It was just cranking but still the bearings were probably dry and it might have damaged the surface a little.

Secondly, I've been very hard on the engine, with a couple of mis-shifts before I installed the MR short shifter and a couple of over-revs in downshifts. I was planning a full rebuild at the end of this season anyway. I guess this just brings it forward a little.

The machine shop is doing a hone on the bore, and is going to clean up the rod. The crank that was in the engine was already at max grind so I've purchased a another crank from Automotive Plus (thanks guys). I've got new rings already on the way from the US and I've managed to source some ACL bearings of the right size in Aus. Other than that it will be all back together and ready to go again in a few weeks... hopefully!

I'm going to clean out the oil lines, pull the cams and check the head surfaces. There is no powdered bearing surface in the oil, only flakes in the sump. I'll have a look in the oil filter and see whats in it, but I don't think anything has gone through the rest of the oiling system.

I think I might up the oil pressure a bit and also start doing some oil testing.

Magpie · Postby **Magpie** » Wed Oct 07, 2015 7:53 pm

Think about doing some oil sampling when you get the engine back together, this will help build a history on what is going on inside.

madjak · Postby **madjak** » Wed Oct 07, 2015 8:28 pm

Most definitively... I think a 3 monthly oil analysis will be required from now on.

The effort to simply source the bearings and rings makes this an exercise I don't want to do very often! All up it's not going to cost much more than a standard refresh but it's timing isn't the best, with only 5 weeks to the Hillclimb Championships!

Magpie · Postby **Magpie** » Wed Oct 07, 2015 8:33 pm

You need to do the oil sampling EVERY change. Once you get some history on the oil then you can decide when to do the changes. Many years ago I was working on a mine site where they setup an oil sampling lab at the workshop and it is amazing what it can tell you. Plus, at least for mining extending oil life is an incentive plus being able to 'see' potential failure before it happens allows components to be changed out or even left in for longer.

bruce · Postby **bruce** » Wed Oct 07, 2015 9:24 pm

Your thread title should now read '0+HP N/A'

madjak · Postby **madjak** » Wed Oct 07, 2015 11:06 pm

Its just a rebuild... will be back up and running again in 3 weeks. I'm actually looking forward to putting it all back together. I've been dying to pull it down and play with all the cool bits!

sailaholic · Postby **sailaholic** » Thu Oct 08, 2015 8:54 am

You should read the thread here about oil or read this link (same content) http://www.bobistheoilguy.com/motor-oil-101/

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