Hello everyone,

Just had some thoughts about my project vert. I am debating on doing a bigger port job on it and if I go that route I will most likely end up 'squirting it.

I have worked with MS before on a test engine with no load, we never tuned the spark tables, only got them to theoretical values. I have been wondering what is involved in tuning the spark table, on a dyno of course. From what I know so far, you want to adjust it until you see peak horsepower for the adjustment, if you add more advance and see it drop, you back off to the point where you got the max HP. And I would assume you just keep going at it for different loads and RPMs correct?

Now, I am assuming before you get to this, you would want your engine running reasonable AFR's. Would you adjust fuel at all on the dyno once you have it dialed in to your target afr's and you are adjusting the timing table? Also, do you guys do changes of timing in a range of cells or just single cells?

I have access to a dyno which I can probably use unlimited times at my university.

This is just some things I am curious about while I day-dream warmer days

I appreciate all the feedback, I don't mean to steal your knowledge of tuning, just want to get a better idea of the way it's done. Thanks.

 

Your idea of tuning timing is basically correct. Max advance should usually occur at peak torque.

You will have to make minor AFR corrections as you change timing...as the engine starts to make power power, more fuel will be required.

Don't go crazy in boost. You can certainly make some power but the benefit is outweighed by the risk. Be at 15 degrees once you get to about 6-8 PSI, then go down to 10 in a linear way from 8 - 15 PSI and stay at 10 thereafter. Some may disagree with this but this is what I do all the time and have never blown an engine and always made good power.

Split should start around 15 degrees at light load, go to zero by atmospheric and then be at 15 degrees again under boost.

To tune timing properly you need an EGT gauge. As EGTs start to rise, you are giving it too much advance.

 

I have never tuned my car on a dyno or with an EGT gauge, but I've read a lot about timing and feel I have a pretty good grasp on it. I have used some timing maps from this forum on my RTEK successfully and from what I undestand they are pretty safe/conservative. I know in my sig my car is on a dyno, but I was just baselining HP at stock boost 7.5psi (223hp, 191 tq) at a dyno day at Forged Performance here in Portland, OR.

I agree with Aaron here, but most of what I've read suggest 15 degrees at 15 psi at peak torque and taper up from there. But, he's right on with the split and the comment about timing under boost. EGT's can also rise if its too retarded as well. (I don't know about porting and how that might affect timing, I am running stock ports) If your running pump gas the timing should stay conservative, but with race gas and/or aux injection you can advance it some (?degrees?), not sure how big the results vs. risk from advancing it though.

In this post, Arghx has answered some of my questions about tuning Timing.
https://www.rx7club.com/showpost.php...2&postcount=19

I hate this mentality. Your not stealing anything. Like us newb tuners are going to go out and start trying to steal a professional's business. Yea right. IMO, There's 2 type of people, the ones who will pay someone to tune/build their car and those who won't let anyone work on their car or have no other choice but to do it themselves.

Give a man a fish he can feed himself for a day. Teach a man to fish and he can feed himself for a lifetime.

Good luck, I hope we get some more good timing information here.

Some other good threads...

https://www.rx7club.com/rtek-forum-168/timing-spreadsheet-879376/

https://www.rx7club.com/rtek-forum-168/new-boost-based-timing-maps-885556/

 

Wow... Thanks for the replies Aaron & Nick. I have been reading your posts and also the links you provided, the funny thing is I didn't find anything when I searched here but I guess the information is there.

I just want to add a few more links for future searchers:

https://www.rx7club.com/single-turbo-faq-122/advancing-timing-high-rpm-101226/
https://www.rx7club.com/single-turbo-faq-122/how-many-run-no-split-timing-325400/

Lots of information like I said, it pretty much covers most of my questions. I might be tuning the engine N/A at first until I have time to toss in the slug once I graduate in the fall. I just want to get everything together once it gets warmer.

Another thing I just remembered. What would safe EGT's be on a rotary engine when tuning? What would be not safe? And as you adjust timing, you guys say watch for the EGT's, will there be a point where it just jumps up and I can say thats not safe and back of, or is it gradual?

I might come back to this thread later too once I get to that the stage and have more questions....

 

EGTs vary wildly based on where the sensor is. But under load, you shouldn't be seeing much over 1700 degrees on a NA, less on a turbo car. However you will have to determine this for yourself.