9 degree 665, Q16 at 32*

quote:

Originally posted by sr4440:
What A/f ratio are you running?

The reason I ask is I have had maybe a dozen people come in with a known good methanol combination, we run it, get dyno numbers, find out they are running a rich A/F ratio. Then pull a bunch of timing, start leaning the engine out until it stops making HP, then add timing back in until it stops making HP. Always end up with less timing and more HP. Usually add a little more fuel just for the engine to not be as weather sensitive.
But your engine may be different, I don't believe I have done a 9* head engine.

Here's something fun Google "At stoichiometric air/fuel ratio which fuel burns faster gas or methanol."

My afr's are 5.0-5.2 at the hit, leaning to about 5.6ish on the top end. Car kept picking up and it's happy spot was at 38*. I've ran it at 32, 34, and 36, and all were slower. The afr's I run are also it's happy spot. If I lean it, it will slow. If I richen it, it will slow. So it's pretty well tuned where it's at. My chambers are softened, 7* cut.

Depends on combustion chamber configuration, base compression ratio, fuel, stroke/bore combo, weather.

Looks like it's a 605 with conventional heads. I'm assuming 4.5" stroke 4.6XX bore.

On my combos (598, 4.5" stroke 4.600" bore, conventional head, methanol/MFI, similar cam) I've run anywhere from 32 to 37. 33/34 was best when the weather was good, but when weather got bad it seemed to want a little more timing 35/36 is where I landed in the nasty hot months in south louisiana (humid, sunny, hot 95+ degrees). Not sure.

Similar experience to what someone else posted on the dyno with a conventional headed motors injected/methanol, lower timing and leaner fuel mixes made the most power. Usually picked timing up 1 degree and fattened up a tad to cover a wider range of weather days. I also stuck one in the car with the same best power tune from the dyno (33 degrees/lean) and made the fastest passes but that was on excellent weather and track day.

20 Degree motor on methanol only liked 32 degrees and only 1 pill in the injection (fater than conventional motors i've had), anything outside of that and it was slow. Same thing on the dyno.

quote:

Originally posted by Alaskaracer:


My afr's are 5.0-5.2 at the hit, leaning to about 5.6ish on the top end. Car kept picking up and it's happy spot was at 38*. I've ran it at 32, 34, and 36, and all were slower. The afr's I run are also it's happy spot. If I lean it, it will slow. If I richen it, it will slow. So it's pretty well tuned where it's at. My chambers are softened, 7* cut.

I don't drought you. I have had some BBC that just like timing, I just go where the data tells me.

588. Injected alcohol. Crank trigger but I run at altitude. Timing is locked at 37 but I also use a start retard to crank the engine over. Never had it on a dyno but it runs well.

SR440,

Interesting read on fuel burn rates, Ironic I guess is word looking for, Faster burn rate fuel seem to require more timing but at same time lot more fuel for faster burning. Firing off sooner when burns faster just sounds backwards. Alky and gas are lil difference tomonmg wise with 6.--:1 and 13.--:1, But throw nitro in mix and looking at 1.5 or 2: 1. Nitro needs lot more timming. I mean 55* to60* is a mid range for injected nitro at 95%. A timing that wouild knock bearing out oif alky motor. This with 12 to 13.5:1 compression.Yet nitro is faster burning fuel? Love it when you bring the science of the tech to the conversation.

Now I can work on how all applies or dioes not with much larger chamber like a Hemi. Yea I know could have built BBC and skipped this part but where is the fun in that.

This message has been edited. Last edited by: wideopen231,

quote:

Originally posted by wideopen231:
SR440,

Interesting read on fuel burn rates, Ironic I guess is word looking for, Faster burn rate fuel seem to require more timing but at same time lot more fuel for faster burning. Firing off sooner when burns faster just sounds backwards. Alky and gas are lil difference tomonmg wise with 6.--:1 and 13.--:1, But throw nitro in mix and looking at 1.5 or 2: 1. Nitro needs lot more timming. I mean 55* to60* is a mid range for injected nitro at 95%. A timing that wouild knock bearing out oif alky motor. This with 12 to 13.5:1 compression.Yet nitro is faster burning fuel? Love it when you bring the science of the tech to the conversation.

Now I can work on how all applies or dioes not with much larger chamber like a Hemi. Yea I know could have built BBC and skipped this part but where is the fun in that.

Nitro is a SLOWER burning fuel so it requires more timing but it is Detonation prone. Toluene mixed with Nitro can help some with detonation.

quote:

Originally posted by Curly1:

quote:

Originally posted by wideopen231:
SR440,

Interesting read on fuel burn rates, Ironic I guess is word looking for, Faster burn rate fuel seem to require more timing but at same time lot more fuel for faster burning. Firing off sooner when burns faster just sounds backwards. Alky and gas are lil difference tomonmg wise with 6.--:1 and 13.--:1, But throw nitro in mix and looking at 1.5 or 2: 1. Nitro needs lot more timming. I mean 55* to60* is a mid range for injected nitro at 95%. A timing that wouild knock bearing out oif alky motor. This with 12 to 13.5:1 compression.Yet nitro is faster burning fuel? Love it when you bring the science of the tech to the conversation.

Now I can work on how all applies or dioes not with much larger chamber like a Hemi. Yea I know could have built BBC and skipped this part but where is the fun in that.

Nitro is a SLOWER burning fuel so it requires more timing but it is Detonation prone. Toluene mixed with Nitro can help some with detonation.

well no ****. If read article the way it states it sounds just oppisite.Not really as to nitro but as to AFR. W Since notro is about 3 of alky since contians good amount of oxygen in the fuel itself.Which was point of post.
Not saying have more nitro,experiance than everyone here , but betting more than most here. Do not need lesson in how it burns or why needs more lead. just pointing out that article states A/F ratio as part of it and burn rate and understand whast it means but the wording just makes seem otherwise. IMO Have two gallong toruene in building get it from Sherwin Willaims paint store. Not legal in comp. at NHRA eventd.

This message has been edited. Last edited by: wideopen231,