SCCA EMod MGB GT V12 Build

So the last event was a bit of a disaster for me. On the Friday before I was on the dyno to try to get more boost at low rpm because I had been making zero boost below 4000 rpm. During testing, my 69,000 mile fuel pump (the one that is supposed to pump 2500 psi) failed, which would explain why the engine kept running lean. I put another fuel pump on Saturday and came to the Sunday event. During my first run the car felt good at first but quickly started to break up at high rpm and was way down on power. On my 2nd run, it felt like it was running on 3 cylinders and on my 4th run it felt like it was on 2 cylinders and I had to shift to 1st gear where I should have been able to leave it in 2nd. I got it back to Speedworld and performed a compression test and discovered that 2 of the cylinders have only 30 psi compression. I stuck a borescope down there and the video clip of that is included here: https://www.youtube.com/embed/GmpT05JicJ0

Question for you- how much engine data can you record?

Just the generic PID outputs, or can you record some of the GM engine data they can record over the CAN network?

If you can get the expanded list, then record the fuel rail pressure and the desired pressure. That will tell you if you are going way beyond the fuel pump's capability. And if you can stick in a supply fuel pressure sensor- you can figure out exactly where the fuel problem is.

Also- record the a/f that the ECU is getting, and the desired A/F ratio.

(given how we do it, and I assume GM does/did it the same- there's a pretty rich amount of data that can be recorded- but that assumes your tuner can do that)

At this point do we rebuild one or the other bullets or try our luck on another jyard LHU ($$$$$wise)? if it weren't for bad luck you'd have no luck at all.....song in there somewhere

In reply to alfadriver:

After a few pulls on the dyno, we added the desired fuel pressure and actual fuel pressure PID and there was a big difference. Then, while loading a new program, smoke started to pour out off the foam insulation around the fuel pump solenoid. This was the moment that the pump failed. The car wouldn't do anything but idle after that until I put the other pump on. The desired and actual fuel pressure matched so I went to the race event the next day. I think something happened on the dyno that damaged the rings and during the event, silly me, I put extra springs on the wastegate to get more boost down low. These springs worked, I was getting 10 psi at 3000 rpm, but I think the wastegate was too slow to react and I overboosted to 31 psi. It was just a spike, not sustained high boost but it was probably enough to push damaged rings over the edge. I should have played safe but I went for it, lesson learned. The Regal motor (the original one) is being rebuilt with neutral balance shafts and ARP head studs so it will be slightly better than stock. Because of the Variloc diff that I bought, I have to give up on the the fancy pistons and rods for now. I'll keep rpm below 7000 and boost below 30 psi and the Regal motor should hold together.

Neutral balance shafts? Just what it implies?

In reply to 759NRNG:

This explains it: https://zzperformance.com/engine-balance-and-the-balance-shafts/

loosecannon wrote: In reply to alfadriver: After a few pulls on the dyno, we added the desired fuel pressure and actual fuel pressure PID and there was a big difference. Then, while loading a new program, smoke started to pour out off the foam insulation around the fuel pump solenoid. This was the moment that the pump failed.

Do you know how he changed the desired pressure? Smoke tells me that it was way over driven.

Honestly, the table probably didn't need changed- higher desired pressure isn't going to help if the pump is running out of steam- it's flow limited- so once you get past that, nothing is going to help- even higher supply pressure.

So you need to keep track of the desired vs. actual pressure- when the actual starts to fall off the desired- that's all you will get, so no more boost, no more richer, etc. And I mentioned the supply pressure to the pump- more isn't going to help, but too little will. Not sure what GM runs at, but ours are in the 65-80 psi range- to the high pressure pump.

All of the pumps I have worked with are capable of about 400-450 hp worth of flow- at a normal BSFC tuned for raw power. If the cal runs overly rich- that will be reduced.

In reply to alfadriver:

Bad News Racing only tried to alter the tune to compensate for the lean condition at upper RPM, he had no idea that my pump was not putting out the desired pressure until we added that PID to the scanner. You bring up a good point about the electric supply pump, it is good for 100 psi (knocked down to 68 with a regulator) but it might not have the volume I need. However, it was the same pump I was using and got 350 hp/380 ft/lb when I dyno'd last year and my AFR was perfect.

Loose, read the ZZP on balance shafts, thanks. Those cats seem to be the epicenter for ecotec, hey, have you read their article on the fuel systems for these engines?

In reply to 759NRNG:

No, but I will now

When I started to build Pink Panther 4.0, I did not want a fragile race car so I built a cushion into everything. The frame is a little stiffer than necessary, the axles, radiator and transmission are all a little bigger than required. In the end I was 100 lbs over minimum weight and I'm cool with that because, until this season, the car has been absolutely bulletproof. I think my failures this year have been mostly my fault because I made some changes in order to go quicker. I'm going to get a high volume fuel pump this week because I don't want fuel supply to be a weak link. I think a 450 litre/hour should be enough.

In reply to loosecannon:

Before you buy it, make sure the rated pressure is high enough, too. 6 bar or 90 psi should be good enough.

In reply to alfadriver:

Yes, thanks. I have been looking at Summit Racing, Speedway Motors and Amazon. Got any recommendations for a pump around $200?

No, the only ones I can really suggest is a pump out of a modern SHO... Which I'm pretty sure is more than $200. I'm sure GM has one similar.

Loose, here's the zzperf article https://zzperformance.com/2012/09/ on LNF fueling.

I got my lower control arms and front structure back from powdercoat. I told them I wanted pink and they gave me PINK. It looks really good in person but I need sunglasses. Compare the old to the new. I lost the ability to quickly adjust the inner heim joints but I don't need to do that and the pieces that permit easy adjustment are also the things that bent. [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_9593_zpsp9zvp0kn.jpg.html][/URL]

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In reply to loosecannon:

Nice!

Loose, these new arms are your creation or speedway mtrs?

In reply to 759NRNG:

I built these. Here are pics of them on the jig and test fitting on the car [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_9443_zpscbrcz3st.jpg.html][/URL]

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Mad skills boss, speedway might want to get with you and start a business relationship.

In reply to 759NRNG:

I have been too busy designing and building these kart frames for my business. They are flexible like a real race kart frame but are indestructible like a rental kart frame. They take 30+ hours of welding to build [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_9245_zpsb4rzyv8c.jpg.html][/URL]

I assume this LHU is a cousin to the LNF, correct? What I read from zzprf was that there is a mechanical pump on these engines(LNF) actuated by a lobe on one of the camshafts to support the higher pressure at the fuel rail. Zzprf has developed a cam with increased lift on that lobe to support higher boost pressures for those that do that sort of thing. I know this different cam is probably more than the external pump swap, but it appears to me to be the solution....just sayin'

In reply to 759NRNG:

Yes, the ZZP cam gives around 25% more pumping action to the mechanical pump but I don't need that. I am not running out of pressure because of the mechanical pump. Today I put the Regal engine together (the EBay motor is from a Verano) using studs instead of the TTY bolts. It was time consuming but as easy as putting together a small block chevy. I was able to spin it over by hand pretty easily until I got the head and cam chain on, then there was one spot that was a little too much to spin over by the damper. I checked and re-checked everything, all timing marks were correct and the pistons were all around half way up the bores, so I was mystified. I put a bar on the damper and pushed a little harder and the timing chain made a noise and now it spins over no problem. I figure that one of the many chain guides was not quite seated right, and hope it's nothing else. I did a quick compression test and all cylinders are really good. [URL=http://smg.photobucket.com/user/loosecannon/media/MGB-GT/IMG_9601_zpsfnitntgb.jpg.html][/URL]

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Sorry, I now understand the situation (fuel), it's not pressure but volume that is the culprit.....I'll go back up in the stands and quietly watch.

In reply to 759NRNG:

I'm not sure what the fuel situation was except that the Verano engine was not making the boost of the Regal engine, no surprise because one has 12,000 miles and one has 69,000 miles. We assumed it was a wastegate issue and turned up the boost but maybe it was just a weak fuel pump? We'll never know what caused the Verano engine to fail but I am replacing the fuel pump and regulator because they are a question mark right now. The pump is supposed to have enough volume for 500 hp.