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yes its at every aral gas station... every shell has v power 100 which is 95 = (100+90)/2

The most standard no name gas stations only have 98 which is 93 = (98+88)/2
Yes I know the difference between RON and MON but never heard of such high octane these days? Thats why I thought you used 96RON since it was a mix of 98 and 95 avaible in Sweden some years ago. In Sweden 98RON is highest we had Shell v-power 99RON a while back but it was tested and wasnt up to spec so disapered. In the 60`s and early 70`s leaded 100+ was avaible here but now only 95 (91 Us) and 98(93 Us). Never seen higher than 93 pumpgas in Us.
No aral stations in Sweden, will the new EU laws still allow that 102 gas? In Sweden we will only have e10 old 95(Us 91) and e5 old 98 (Us 93) soon and e5 will not be avaible at every gasstation.
Glad I used alu heads and moderate compression so I can use e10.
 
Yes I know the difference between RON and MON but never heard of such high octane these days? Thats why I thought you used 96RON since it was a mix of 98 and 95 avaible in Sweden some years ago. In Sweden 98RON is highest we had Shell v-power 99RON a while back but it was tested and wasnt up to spec so disapered. In the 60`s and early 70`s leaded 100+ was avaible here but now only 95 (91 Us) and 98(93 Us). Never seen higher than 93 pumpgas in Us.
No aral stations in Sweden, will the new EU laws still allow that 102 gas? In Sweden we will only have e10 old 95(Us 91) and e5 old 98 (Us 93) soon and e5 will not be avaible at every gasstation.
Glad I used alu heads and moderate compression so I can use e10.
RON 98 is also E5, just like RON 100 from shell or RON 102 from aral. Its here since many years and i see no reason why it should vanish due to Euro7 Regualtions.. There are many cars from before 2000 which cant cope with E10, so there will always be E5 availability..
 
RON 98 is also E5, just like RON 100 from shell or RON 102 from aral. Its here since many years and i see no reason why it should vanish due to Euro7 Regualtions.. There are many cars from before 2000 which cant cope with E10, so there will always be E5 availability..
Yes 98 RON is going to be e5 here 1 of and August now its not e5 here. Most 98 here is e free. You got e10 earlier in germany than in Sweden I belive?
Maybe e5 will stay but if not enough e10 is sold they will put extra tax on the other fuels so e5 and other blends may be alot more expensive. E5 is only promised to stay untill 2025 Ive heard but it may still exist after that? If demand is high enough here only 2-3% gas thats sold are 98 RON. So maybe not? Next step after e10 is e15 and than things may not work as good anymore........ At least classiccars are tax free in Sweden and if 50 year or older no vehicle inspections.


Anyway most of us here only run 91-93 MON and if engine is built and tuned for lets say 91 no need or benefit to run 93 it will only lighten your wallet.
 
I've read the timing 101 article, but am still confused about the mechanical timing.
I have a 496 with a hyd roller cam, 238/243 dur 634/643 lift 112lsa, Accel HEI.
My best vacuum idle is 14.5/15".
I have the initial timing at 20*, vacuum advance hooked to manifold vacuum.
The motor seems to like it best this way for the power brakes.
When I unplugged the vac advance and ran the motor to 3000 rpms the mech advance was 35*, +20* would be 55* total. That seems very high to me.
I changed the dizzy springs a few times and got a best of 32* mechanical. So that + 20* initial =52*. Still too high?
The car runs good, don't think I hear any pinging. Im just afraid of ruining my new motor. I'm pretty unfamiliar with playing with mech advance. Any other way to lower it? Or is 52* total fine for my combo? Vacuum advance hooked to manifold is definitely necessary on it. It made a world of difference when I changed it to that from ported.
Do you know comp ratio? Your signature says alu heads?
52 might be ok all depends on the combo.
Im running 35 total+ 16 deg from my vacuum can.
 
if your combo runs reasonably lean at cruise that 52 is OK. Lean mixes burn slow and will like the extra advance. Rich mixes won't.
 
Whats your altitude and fuel? Plays a role too.
The more towards sealevel, the denser the charge and the less advance in general the engine needs.
You can keep a aggressive timing, but then use premium or better fuel for detonation protection.

I have a 496 with a hyd roller cam, 238/243 dur 634/643 lift 112lsa, Accel HEI.My best vacuum idle is 14.5/15".

For comparison:
Living at sealevel using 96=(102+90)/2 fuel: 496, 238/248 Dur. - .578/.608 lift - 110 LSA - MSD 6AL - Vacuum at idle 1000 rpm ~10-12"
(i expect my gauge to have 1-2" offset - powerbrakes work perfect)

I run 18° initial + 18° mech. (all in at measured 3800 - 2 heavy silver MSD springs) -
+ 6° vacuum (So 24° idle timing or 42° cruise timing).

I expect there is room for more timing.. but i just want it to perform and still be way on the safe side. Gas mileage is no object. Safety is..
Have you tried a faster curve than that? One thick silver and one thin silver? That’s late to have timing all in for most performance engines.
 
Yes 98 RON is going to be e5 here 1 of and August now its not e5 here. Most 98 here is e free. You got e10 earlier in germany than in Sweden I belive?
Maybe e5 will stay but if not enough e10 is sold they will put extra tax on the other fuels so e5 and other blends may be alot more expensive. E5 is only promised to stay untill 2025 Ive heard but it may still exist after that? If demand is high enough here only 2-3% gas thats sold are 98 RON. So maybe not? Next step after e10 is e15 and than things may not work as good anymore........ At least classiccars are tax free in Sweden and if 50 year or older no vehicle inspections.


Anyway most of us here only run 91-93 MON and if engine is built and tuned for lets say 91 no need or benefit to run 93 it will only lighten your wallet.
yeah E10 is here since maybe 5 years if i remember correctly..
I guess there will always be one E5 gas available at the gas stations.. most likely it will be the 98 version or premium+ (100,102 etc) versions...
 
Have you tried a faster curve than that? One thick silver and one thin silver? That’s late to have timing all in for most performance engines.
talked to my engine builder and other guys using this engine on sea level and there is no reason to increase timing further.
Its open chamber heads which are treated by mark jones and unshrouded valve wise... They burn relatively efficient and quick.
The pistons have rather low domes of 18cc..
So for a BBC the flame propagation is way way faster than in old untreated closed chamber heads with 43 cc domes..

My curve offers 32° at 3000 rpm and for my chamber/piston-design combusting dense sealevel air thats enough.
Most guys running on sealevel leave it at 32 at 3000 when running 91..
Since i have 96, i dare to go further, adding 4° more till 3800 resulting in 36... the dynorun was done on 35.
I do burnouts till 3rd gear like 80mph/130 kmh - the low end torque is enough already and there is no more performance to gain other than even more burned rubber..
So i like to leave a proper margin of safety...
hence the (unneccesary) high octane fuel.. its cheap extra insurance..
 
My 496 runs best and made peak HP at 34 degrees all in at 3000rpm with vacuum disconnected.
Toocool........Curious what is your combination?
 
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Whats your altitude and fuel? Plays a role too.
The more towards sealevel, the denser the charge and the less advance in general the engine needs.
You can keep a aggressive timing, but then use premium or better fuel for detonation protection.

I have a 496 with a hyd roller cam, 238/243 dur 634/643 lift 112lsa, Accel HEI.My best vacuum idle is 14.5/15".

For comparison:
Living at sealevel using 96=(102+90)/2 fuel: 496, 238/248 Dur. - .578/.608 lift - 110 LSA - MSD 6AL - Vacuum at idle 1000 rpm ~10-12"
(i expect my gauge to have 1-2" offset - powerbrakes work perfect)

I run 18° initial + 18° mech. (all in at measured 3800 - 2 heavy silver MSD springs) -
+ 6° vacuum (So 24° idle timing or 42° cruise timing).

I expect there is room for more timing.. but i just want it to perform and still be way on the safe side. Gas mileage is no object. Safety is..
Is engine built, dynoed and tuned on that german high octane fuel? If not run the octane it was built for you are only wasting money and its not better.
The higher octane gas burns slower, and therefore makes less power...
 
Is engine built, dynoed and tuned on that german high octane fuel? If not run the octane it was built for you are only wasting money and its not better.
The higher octane gas burns slower, and therefore makes less power...
good question.. its build, and tuned in US with 91 fuel. But I do all the tune up steps in accordance with my engine builder.. he says the 95-96 fuel is about perfect for my case (short cam, sealevel)

I take extra detonation protection at the cost of a few bucks and a few horses any day.. since i fuel up like maybe 10 times a year and have way over 600 hp in any case..

regarding burn rate and octane rating there are indeed instances where it behaves like you think it should, but its not always the case.

Here is an example:
Fuel Rating - Octane Comparison - Dyno Tests Graphs - Hot Rod Magazine

runs with fuel and respective timing where best power was achieved:

714228
 
good question.. its build, and tuned in US with 91 fuel. But I do all the tune up steps in accordance with my engine builder.. he says the 95-96 fuel is about perfect for my case (short cam, sealevel)

I take extra detonation protection at the cost of a few bucks and a few horses any day.. since i fuel up like maybe 10 times a year and have way over 600 hp in any case..

regarding burn rate and octane rating there are indeed instances where it behaves like you think it should, but its not always the case.

Here is an example:
Fuel Rating - Octane Comparison - Dyno Tests Graphs - Hot Rod Magazine

runs with fuel and respective timing where best power was achieved:

View attachment 714228
I dont belive in all magasine articles, Did they mention the margin of error between the pulls?
Think the shop I use said it was 1% so all pulls are within that marginal if first was 1% low and last 1% high.
If engine is built for 91 thats what I would run but its your money and decision.
Are there many Us classic cars from the 60’s in germany?

With what total timing Did your engine made most hp? And was that with 91?
 
I dont belive in all magasine articles, Did they mention the margin of error between the pulls?
Think the shop I use said it was 1% so all pulls are within that marginal if first was 1% low and last 1% high.
If engine is built for 91 thats what I would run but its your money and decision.
Are there many Us classic cars from the 60’s in germany?

With what total timing Did your engine made most hp? And was that with 91?
when you read the article fully you can see those guys did several back up pulls to verify those numbers and were doing timings sweeps across those final max hp timing numbers.
So in other words those number are only 1% different, but rather repeatable and consistent.
But then again everyone should always doubt everything fully when it comes from the internet... i do the same
my engine made max hp with 35° with 91 fuel. Would have been nice to get a dyno pull with 95-96 fuel..
in correspondence with the builder added one degree and several octane digits...

Yeah there are pretty many 50s-70s us cars here in germany, especially in the south around the former us military bases..
 
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