CA gas and 10:1

[slowpoke]

So, i was just thinking, I’ve read a bunch that says 9:1 or so is the most us californians should use on pump gas.  But if i wanted to run higher compression so i could have more fun on track days, could i run two different advance curves on a 123ignition, one for street and one for track when i can use some better gas?  (Most tracks have 95 and 100).

 

any thoughts?

 

[Schnellvintage]

I have used and ran reliably 10:1 CR pistons with the 264 stock cam on CA premium fuel (91 or more octane) for years, without issues.. as long as your tune is correct ( jetting, timing, valve adjustment)
Cheers,
Matt


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[slowpoke]

Well, i was going to get a wide band to make sure it ended up in a good place.

Edited October 30, 2019 by slowpoke
Fix

[TobyB]

What cam will you use?  Something more aggressive will actually do a bit better at low revs,

as the effective compression ratio will be lower.

 

What induction will you use?  EFI can be tuned to go rich in conditions where detonation might occur.

 

t

 

[Schnellvintage]

+1 for Toby regarding cam type.


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[slowpoke]

have a lynx intake w/ a 45 and a header on a shelf.  was wishing for a cheap 304-ish cam.  any suggestions for that?  been slowly trolling here and craigslist for parts and am just about ready to pull the trigger on a rebuild.  saw the post for 10:1 pistons and thought ...  maybe.  prior to that i was thinking 9.5 or so and  292-304-ish cam.

 

primarily track car now.  roll bar, one seat. engine burns oil like crazy so feel bad doing grocery store runs.  bought a spare engine that i was going to rebuild and swap in. of course, the head in the car and the head on the spare are not the same....  e12 vs. e21. 

 

[slowpoke]

oh, live an hour and change from Laguna Seca, 1.5hrs from Infineon, 3hrs from Thunderhill, 3 hrs from Buttonwillow,   need to get the track car a bit sportier!  currently very willing to tow to the track, but want to be able to drive on the street to make sure its ready for the track...

[rcf925]

24 minutes ago, slowpoke said:

oh, live an hour and change from Laguna Seca, 1.5hrs from Infineon, 3hrs from Thunderhill, 3 hrs from Buttonwillow,   need to get the track car a bit sportier!  currently very willing to tow to the track, but want to be able to drive on the street to make sure its ready for the track...

 

Thats pretty much where I am, Just finished build with 9:8 CR, .292 cam. Car is set up basically for street and track Bilstein Coilovers, , 5spd, LSD 3.91 and I'm 2 hrs from Laguna Seca, Buttonwillow. I have 002 distributor with Pertronix and no issues so far on 91 octane, Plenty of torque and high end

[bmw1602.com]

I ran those 10.1 pistons I have for sale with a 304 cam on pump CA 91 gas.

 

In fact my "new" race motor....is also 10.1 ish with teh same 304 cam and I still run 91 pump gas.....4 races done this year.

 

even dyno tuned it 36 degree's timing....no issues...... 134rwhp.

 

all documented in my build thread

[slowpoke]

bmw1602.  that's sweet.  i'll check the build thread.  thinking about your pistons, but currently i think the head that goes w/ them (e21) is on the car.   do you have a 304 or is there a "sort of equivalent" regrind?  cams are pricey.  ok, everything's pricey.    looks like i've got some more reading to do over lunch!! woohoo!

[kbmb02]

@slowpoke - I’ve got at least one ‘304-ish’ camshafts ... though, I guess it depends what ‘cheap-ish’ means to you. And me.  

Send PM to discuss. -KB

[kbmb02]

-

Edited October 30, 2019 by kbmb02
2x post

[Einspritz]

I say invest in a J&S with knock retard and add a wideband, tune the fuel to your best and be done with it. Just because you don't hear knock doesn't mean its not.

 

and / or invest in race gas at the track....only $90 to fill up twice a day. :)......unless you have a Tii, which will require extensive  tuning for each.