Hi guys, wondering if I could get away with this:
408 or 416 inch small block
undecided on heads yet
.036" quench
10:1 comp ression
34~35 degree total timing
honest 400~450 hp (crankshaft)- not desktop dyno
and still be happy on 87 octane pump gas?
Thanks for any input!!

this may not be the most educated answer, but when i ran my 340 (.040 over, mild cam, and slightly ported heads) i always ran super (91 octain) cause it didnt seem to like regular 87. now i have almost completed my 416 stroker build, and i will only be running super.

I'm curious to see the replies on this one. I'm a fan of daily running on the lowest grade (cost) fuel, and racing on the highest pump grade. Most engine builders I've talked to question why anyone would build a motor like that. My answer is that I've watched the octane rating drop thoughout the years and the price of fuel go up. Not everyone builds a race engine, but most tend to race the engine they build.

I built an 87 octane RB that is alot like a 2.2 engine. By that I mean a cast block and aluminum heads, with about 9.3 compression. I chose a cam and chassis for broadest torque where I drive the most. The torque is shameless, the chassis hooks with DOT's, and is a joy to drive. No tall gears or high stall converter required. Low 12's with high 11 mph at 4,000 lbs.

I think I know what you are after, but I haven't done it with a small block yet.

Is there a real reason you want to build for 87 octane? We have pump 94 here in town however only one gas station has it. For most other places the standard pump premium seems to be 91, which is commonly available everywhere. Really you can get away with a lot, depending on cam timing and how good you are at curving your distributor.

I believe it's possible. .036 quench is a good start but make sure you have a piston and cyl head with decent quench pad area. Doing that, I doubt you gain anything by going up to 34 total advance. The 87 will require less advance anyway meaning, not to prevent detonation, but it just won't require as much advance. Especially with excellent quench. The camshaft duration will determine this ability to run on 87 also.

My 408 with 10.2:1 and 236@ .050 cam, .038 quench using a step dish piston and magnum heads/polished chambers made no more power with more that 30* total advance. This was using 93 pump with 10% ethanol. Made 526hp 496lbft only tuning for a couple hours.

To push the limits on 87 would require some trial and error testing though and probably some cash.

I would say it's possible but why?

When you run higher compression you will get slightly better miledge and you can run almost 1 full point higher on premium than cheapy crap. It will also make more power and TQ and you will feel better when you try to

I did this on my MPG experiment engine and it basically pays for it self. It also is nice because thease type of builds don't get great miledge so you won't have to stop to fill it quite as often

I run 87 in mine but I'm at 5000 ft. You'll need magnum heads at the minimum but eddies would be best.

why build it? I guess I'm just studying my options really...and I wonder if it makes more sense to have 400~450 hp on 87 octane than 450~500 on 93 octane. This will be for my AAR which would be just a family cruiser. On the other end of the spectrum I would seriously consider an engine built strictly for E85 since it's locally available in my area. The only gripe I have with the E85 situation is when I drive out of my local area and there's no E85 to gas up with, then I need to carry $$$ of octane boost in my trunk.
I think it would be neat to find a killer combo that's compatible with 87 octane cheapie gas.

With iron heads I don't think it would do very well on regular. You would have to take so much timing out to prevent pinging you would lose power and efficiency. With Al heads it might just work at 10:1.

I'm running 11.2 cr with a cranking psi of 205 on 93 pump with a 360 and J heads. if you do your homework it can be done and powerful.

My grandfather has the MP 406 LA stroker in his Demon. It will run on 87 with no apparent knock. We normally use 93, though, because we haven't had time to dial in the timing to use 87 and feel safe doing it.

I can’t help on a small block but my 6bbl/440 is 8.6 to 1, cranks @ 150-155 lbs, weighs 4160# with me in it and runs 13.1 @ 107. Auto, 3:23’s, full exhaust & 215/70 radials. Just has a little head work, Hughes 215/223, 112-lsa cam, headers & low compression pistons. Went low compression many-many years ago, ('quench' was a new word.) around the time leaded got hard to get. I drive a lot, wanted cheap gas & vacuum advance. I can get as high as 16 mpg @ 70 and always run 87 gas.

it's also hard for me to believe that octane rating by itself would yield a mpg increase...in a knock sensor equipped vehicle yes, but in something with fixed (or a predetermined advance curve) timing? I do believe that some hi test fuels are better than others and may end up making better power, but that's more than strictly a change in octane.....

I don't beleive the octane rateing would increase MPG at all unless your timing was too far advanced for your 87 octane or if you had so much compression it was pinging on 87.

What I am saying is that you can increase the compression at least 1 full point if you are willing to run premium. Increased compression is pretty well documented to increase MPG a very noticable amount. It is also a proven way to increase HP and TQ. So in short you run higher compression and higher octane together to get better MPG, yes it costs more but the increased MPG offsets most if not all of it.

As a builder, it's possible as others have stated. To get the most out of it will take some trial and error.

Also, some believe timing is a good thing. That's simply not true. That's negative work against the piston as it rises. We don't have instantaneous combustion so we have to have advance to complete combustion by around 15* after tdc. You want the least amount the engine makes power with. The better the quench, with good compression, the less advance you will need. Then you have other factors like operating temp, DA, and when intake valve closes as the piston rises from bdc.

With a custom engine, whatever the customer wants...

My 360 with 10.7 to 1 comp,and my 416 with 11.9 to 1 comp. run just fine on 93 octane gas,using aluminum heads..

You say you are undecided on heads, but you want quench... That pretty much eliminates open chamber heads without a bunch of machine work (or domed pistons which have fallen out of favor). A magnum style head (assuming you are not dealing with early HP 340 pistons that are above deck) will let you get quench easier (prevents detonation), and you can then also go with less timing (also prevents detonation). So with quench and less timing, you are greatly increasing your ability to run on 87. Heat builds power in the compression chamber as long as you do not have detonation. Octane has a cooling effect in the chamber, and so helps prevent detonation. But dumping octane in an engine that does not need it can actually reduce power by cooling the chamber more than necessary.