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The General Leif, 142 endurance racer

The difference in cam timing is the blue and green lines, correct?
Yes, but? I also leaned it out a bit. I?m not 100% certain how much the gains/losses are exactly from the timing, the tuning or something else. The last three runs we did pretty close to back to back. I did two pulls at 5 advanced and the first one had better top end than this one past peak hp but the peak (with smoothing turned on, anyway!) and peak torque were less. The only changes between those two last runs were I leaned out everything other than the leaner bump that?s around 13:1 between 4600-4800 or so. I was fighting that lean bump the entire time we were there. I think it has something to do with our injector angle because it hasn?t been there before the last race we did and we changed intakes due to the other one continuing to break.

More info later!
For porting, it's just a 531 with the intake guide boss streamlined and a lot of bowl work. The intake flange side was also straightened out a bit as well. Exhaust is just the usual cleanup with the biggest SSR you can fit.
3-angle valve job, back-cut and narrowed intake valves.

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The chamber got a lot of work, Erland suggested a little less material removal around the exhaust so I'll try that on the next one.
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That flat torque between 2.5k-5.5k :love:

1. Are you running in open loop all the time? (lambda flag off)

2. I see you mentioned 29 degree max ignition timing, but I am curious how (un?) steep the ignition curve is with a hawg engine setup like that.

3. (A generic question) Why do most dyno plots start up there in the rpm? Why isn't a lower start measuring point of 1000 rpm done?
1. Yes, open loop all the time.

2. I’ll have to get on the tuning laptop some day to take a screenshot of the map. It’s not dialed in by any stretch as we never did any real tuning of that map, but it was at least not losing power when we took timing out of it at WOT so we ran with it.

3. Many engines don’t like to run at that low of rpm, and or the tuning isn’t good, or people don’t want to wait that long for the engine to rev up, or that area of the rpm range isn’t relevant, or… haha. I like to start my pulls down lower than many people do, but this current setup does not like WOT at low rpm and will go pig rich with it falling on its face for the most part.

Sorry for the delay!
Ps. We’ve built a new motor and continue to eat camshafts every race. We might finally have a potential solution, but thicker oil and an oil cooler were not it. Maybe knocking the edge off the tops of the shims with Emery cloth is the trick? It’ll be expensive to find out. We may go with a hardened camshaft too, or maybe a shim under bucket setup to get a slightly larger diameter surface for the cam to ride on, or… I don’t know. It’s depressing. The car is a beast though!

We also bought some knock off 48mm ITBs that may go on it one day with modern engine management. We’ll see. I don’t have a lot of time for it at the moment.