Hey everybody!
After a year... here's a major update to this build. I do apologize to everybody who was following this thread, about the lack of updates. Like I mentioned to Ralph in the above post, things have been a little crazy in the last year, but it is a good crazy
KMS647 is...... finished! Well beside the ever ending tinkering and modifications that we car owners subject ourselves to, haha. It has been an absolute joy to drive, especially this spring/summer season. I "finished" it in April of this year. It has a couple thousand miles on it right now (the mileage on the gauge shows 19,000 but I'll get to that later). The only issues right now, knock on wood, are the cold starts, which I'll explain.
So, let's go back to a year ago. I had the car aligned, it responded well to the alignment and was driving great, except for the engine issues... A quick recap on the engine issues. We were using the FAST EZ-EFI system, with a set of TWM stacks. That system works great when using their carb style throttle bodies, with a typical intake. In that set up, there is enough length in the intake and runners that the air/fuel charge is uniform, and the sensors see a nice uniform charge (I put together an LS1 with that EZ set up, with 2 throttle bodies, for a buddy in France, and that thing runs very, very well). The issues we had were at low rpms. Off throttle, to about 1700-1800 rpms, the car surges a lot, missed, and ran very rough, to the point of being very hard (and annoying) to drive. That was very discouraging, and puzzling to us. The mixture would go rich then lean then rich, and keep going like that, producing that roughness. After playing with it for a couple of months, and talking to FAST (unfortunately who were not helpful), Barry, the engine builder who owns Survival Motorsports, suggested we bring the car to his shop in Detroit to trouble shoot it. He believed it was an issue with the engine needing a more steady load on a dyno, so it can learn and adjust it self....
So in Oct of last year we put the car in a trailer (Thanks Hal!) and put it on the dyno.
From 1900 rpm to redline it ran really well, and we could see the system "learn" and adjust itself, pretty neat. The lower end rpms were still causing issues. In these last few months of troubleshooting, I started to hypothesize (with the input of my "porsche engine genius" friend at Perfect Power) that the stacks were causing the issues, along with that system. Off throttle, when the butterflies open, it produces a lot of turbulent air into the cylinders. The EZ system reacted too quickly and not well to that massive amount of turbulent air that it could not keep up with the O2 readings. That brought on the rapid correction of lean to rich to lean and so on. These stacks are like 8 huge throttle bodies, so the amount of air coming in is massive. That is why the EZ system works well with a typical intake, but not well with stacks. After we confirmed that with Barry on the dyno, we decided to go to the FAST XFI system, so we could manually fix the low rpm issues.
Btw, the low rpm issues were not detected on the engine dyno because most dyno don't operate in that low range, so Barry could have not predicted that issue. I was there at the dyno and also thought it was very well tuned. Lesson learned.
It took a bit of time to get the XFI system. After that I proceeded to lighten up the complicated harness. There were a lot of features we weren't going to use so I too, them out to make the harness cleaner. I took my time with that because I really didn't want to screw something up on the harness!
After ripping out all of the EZ harness, I installed the XFI harness. It wasn't too hard but just took time, and by then it was winter, and cold. I made a special mounting plate for the larger ecu box, so I wouldn't have to drill another set of holes in the firewall! (pics will be posted later, there are on my camera)
While talking to some XFI owners, we decided to get a dual sync distributor from Fast, so we can get sequential firing from the more powerful XFI system. The EZ uses a bank to bank firing (all injectors on one bank fire at once). That makes for a more efficient engine. Here is the distributor. Very cool unit.
Installed. You can see some white moisture spots on the aluminum pieces. We had a freak warm day in Chicago this winter where the temp shot up to 60 degrees. My garage which was at 30 degrees, didn't like the warm humid air coming in and everything, I mean everything, was covered in condensation. I had never seen that before. I couldn't dry the Kirkham's engine in time to prevent these little corrosion spots. Took me a while to get rid of these later!
After installing everything, and waiting for the weather to warm up enough to drive, we tuned the car. I did a lot of it myself but it was pretty time consuming and a steep learning curve. I was making progress but still couldn't get everything right. I probably could have done the whole thing but it would have taking me a long time. I gave the car to my friend a Perfect Power, who, with the help of a very knowledgeable EFI guy, tuned the car very well. It runs great. We still need to put the car on a chassis dyno for the WOT tuning. It was mostly tuned for drivability. The only issue we have, and that we can't figure out, is cold starting. During a cold start, you have to crank the car over 6-8 revolutions before it coughs to life... Very annoying. I have cranked the fuel enrichment for cold starting but nothing.... Hot starting only needs one revolution. I wish that XFI system had a pre-squirt option when you turn the keep on, like the EZ system did. That is one thing I really want to fix.
It has been great to drive! The stiff steering issues are mostly due to the teflon bushings used in the Kirkham steering assembly, and are said to get better with a couple thousand miles. It has gotten better I'm happy to report. *There is an issue with the speedometer as it shows 180 mph (pegged) when you drive, and now shows 19,000 miles, haha. I'm going to send the gauge back this winter. Other winter projects are to move the pedals right a bit. I don't like the pedal position, and it is unsafe in my opinion. A tonneau cover will be installed hopefully too.
That's all I can remember for now... Now for the glamour shots below.....
Arnaud -