FrontEngineDragsters.Org Forum
Technical => Spud Miller's Cave => Topic started by: alkyal on February 23, 2016, 03:40:34 PM
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Does anyone here have real experience with the change-over from straight Methanol to M-5. Jet changes[ with a carb] and timing changes. Do you need a gear change to keep the engine loaded, like on real Nitro.
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I tried it for several runs with an injected SBC. I didn't see much of a change. The stuff won't pass fuel check. I would buy the least expensive alky and add nitro to taste. A 10% blend will show real results.
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I have tried it quite a bit in my injected BBC. We were trying to pick up a little time and decided to try it and it worked pretty good in my car. What we found, at least with my car, is that the tuning changes really made a difference compared to straight methanol. We did need to fatten it up a little.
Drawback of course is the cost.
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I have not tried the M5 but I have had good success with adding a few percent of Nitro. On my motor on the dyno we tried a 20% mixture with 1 quart of Toluene added. If you are under say 12.5 compression you may not need Toluene or if you are running light load like 5% or so. My motor is 14.5 and it needs the toluene to prevent detonation.
Now with that said up to 20% nitro on my motor (your mileage may vary) I did not need to add any timing or fuel and when we tried fattening it up or adding timing it made it worse. Just adding 3% nitro will pick it up about .06. I usually run 2-5% to get it right on the 5.00 index I run. Does not take much. Hope this helps.
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From a known good, working methanol tuneup, M-5 requires about 7% richer in a supercharged application and about 5% for naturally aspirated. Make your carb jet area that much BIGGER and things should be pretty close. Injected guys would make their bypass area that much SMALLER.
No need for gears or anything drastic.
Spud
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I have used it and picked up about .06 . I richened mine 10 percent and it was too much .It really smells bad !
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Tried it out last Sat. Richened it 6% Believe the engine was lean with the original jet as the 6% still showed slight lean. With the jet change, the engine really picked up. Turned 300 more RPMs with the same gear. Bottom line-It was fast for 7 laps-Then pushed out the head gasket. Believe the problem may be too much C/R [over 14.25 to 1] 38-39 degrees timing, but most of all NOT enough Cam Duration. Will rethink the cam before next time out. Also had Ratio rockers [Stock 1 to 1 These were 1.3 to 1 ratio] Not much block or head damage done. It did let out a shower of Sparks. A little show for the Peanut Gallery! Thanks for All your info and input. Al
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Tried it out last Sat. Richened it 6% Believe the engine was lean with the original jet as the 6% still showed slight lean. With the jet change, the engine really picked up. Turned 300 more RPMs with the same gear. Bottom line-It was fast for 7 laps-Then pushed out the head gasket. Believe the problem may be too much C/R [over 14.25 to 1] 38-39 degrees timing, but most of all NOT enough Cam Duration. Will rethink the cam before next time out. Also had Ratio rockers [Stock 1 to 1 These were 1.3 to 1 ratio] Not much block or head damage done. It did let out a shower of Sparks. A little show for the Peanut Gallery! Thanks for All your info and input. Al
I think you need to put it on the dyno. You may find out you are running way too much timing. I started out running 38* and even tried 41* but when I put it on the dyno we learned it did not need that much timing and now run 28*! Yes 28* and it is easier on motor and runs better. My compression is 14.5 with Enderle injection and AFR 235 heads. Much safer to tune on dyno and you can get the fuel mixture perfect in just a few pulls.
Also on the head gaskets I lost a head gasket a few years ago and found some of the head bolts were not as tight as they should have been. I now believe in re torqueing the heads after a few heat cycles and have not had a problem since.