11 to 1 - too much on CA 91 pump gas?

[patrickt]

Originally Posted by 392cobra

Humm,maybe this is why small blocks are faster ?

Hmmm, could be. If it were me, changing the timing is nothing... but having to add stuff every time you fill up is a real PITA.

[rodneym]

This may seem odd but are you certain your CR is 11/1?
So far your problem is just hypothetical, right?
If the simple solutions don't end up working you should consider verifying the CR indepently. That way you'll know what you're dealing with.
Contrary to popular beliefs, the FE gods are human.
rodneym

[rodneym]

I guess what I was trying to say was that if you have problems after trying the easy stuff, your CR may be higher than believed.
I've heard a couple stories describing the above situation.
rodneym

[RICK LAKE]

garry V Yes you can run 11.0 on the street IF you buy a knock sensor kit, limit the timing to the mid 20's in degrees. This will kill the power this motor should make with a better gas. 2 schools of thought
#1 buying 5 gallons of race gas with 100 octane and adding to the tank with every fill about 2 gallons this should protect the pistons from knocking and get a rating of about 93 on a 20 gallon tank. The question is do you have a good place to store this gas???
#2 Snow water/alcohol injection. This is what was used during WW2 to help with poor gas in airplane motors. Snow make a mister setup that will work with any power adder car or high compression motor. Again this is like a custom carb and you will need to setup this system correctly. Distilled water and washer solvent in a 50/50 mix work the best. You get a kit with a 1 or 2 quart tank for the car. This will need to be filled each tank up of gas. You will be able to run more timing, reduce EGT'S, and even pick up about 10-15 HP in the upper end. The motor will also run cooler. Running the system and turning it off before shutting down the motor are the only thing that will take a little time to do, about 10-15 second more than turning off the ign switch. You will still need a knock sensor to get the right flow of fluid into the motor. Too much and you can wash down the cylinders or even hydrolock the motor, not enought and ping and knock city.
Swapping to thick head gasket may drop the compression only .2-.3 points. You could also enlarge the head cc's a little for more drop in compression. This would drop you another .2-.5. This will put you in a safer compression ratio. The rest is as others have said, pull apart the motor and have the pistons flycut to drop compression. The tops should be thick enough for this as long as they are not flat tops. You will need a machinist to do this. It will save you the cost of new pistons. The rotating assembly should not need a rebalance if the same weight is removed from each piston. If time and money are not a major thing, have the pistoned coated on the tops and on the sides to protect them from knocking in the bores and pinging. If too much is removed, would rebalance the whole assembly again.
If you run at night and have heavy cool air, you might not need any of this to be done with watching you timing. Problem is you will be down on power. Rick L.

Ps To Rod Knock, sorry for putting you to sleep with the long info threads. Just trying to give the best info, inside and outside the box. Does this mean I am not getting FRUIT CAKE for Christmas???

[ERA Chas]

I'll say this once more-not sure if the OP is even watching anymore. This is solvable without going into the engine or running 20 degrees total.
I say this because every day I used to document engines' performance on DTS dynos. The bulk of those had these parameters: 91 Octane Shell pump gas, 10.75 to 11.3 CRs, 427 to 632 C/I, AFRs from 12 to 14, aluminum heads, smallest carbs were 850's, biggest were 1050 Dominators. HP ranged from 560 to 825. All cams had 108 to 114 LSAs, were SFTs or juice rollers and had advance from 28 to 36 degrees. All were tested under load and none pinged or ran hot. NONE used octane boost. The drag engines had 12.5 to 14.0 CRs and ran on C-14.
Doesn't it just make sense to try the simplest, least costly, proven suggestion???????

[greg schroeder]

You'll destroy the pistons with 91 octane in time. It's funny how many people do it and then sell the car with the "never been raced" sales pitch.

If you get 116 octane fuel to set in the garage just dump in 3 gallons to be mixed with 10 of the 91 octane pump and it will be around 97 octane. Done.

I most often used 100 octane unleaded from the pump here in Scottsdale, AZ.

[patrickt]

If the OP is still watching, he should try what Chas has recommended. If it doesn't work, then have Barry spec out a new cam for you. Maybe you can change it out without pulling the engine. I wouldn't keep a 55 gallon drum of race gas in the garage.

[ERA Chas]

Originally Posted by greg schroeder

You'll destroy the pistons with 91 octane in time.

Greg,
I respect that you're smart enough to run 10's but how do you account for this statement - nitrous? I didn't encourage the OP to run with detonation.

All those engines I wrote about were warrantied for 2 years and they only came back for broke pistons (and not covered) if they were sprayed by a dummy.

[greg schroeder]

Originally Posted by ERA Chas

Greg,
I respect that you're smart enough to run 10's but how do you account for this statement - nitrous? I didn't encourage the OP to run with detonation.

All those engines I wrote about were warrantied for 2 years and they only came back for broke pistons (and not covered) if they were sprayed by a dummy.

Sorry man. I didn't mean any disrespect to anyone and I didn't think of anyone in particular other than making a general joke because I've watched guys pick up cars from the dealer and thrash on them right off the lot with new engines and also put them right on the dyno with minimal warm up time. Seriously just a generic statement. The fuel thing is because I don't know too many people that take the time to buy the proper fuel for high performance cars. It's just too inconvenient for most.

My car ran some casual 10 passes because I corrected some of the original install power robbing issues and stuff. Basically it was set up better than how it was delivered.
Fuel delivery with 8AN tank pick up to carb
Aeromotive fuel filter
Properly tuned carb from Pro-Systems
Larger surface air cleaner
Different headers that don't cover 1/3 of an inch width of each exhaust port
Side pipes with a bit more flow
Drag radials to start from idle and have 1.7 or 1.8 60ft time
Different half shafts
Detroit TruTrack rear end with 3.73 gears
Light weight flywheel
1/4 tank of gas for less weight
Lower density altitude
100 octane unleaded fuel on Roush original timing

If anyone can let out a clutch from idle, press the gas and shift through gears they'll run a high 10 on a well prepped track with drag radials, 2450 race weight and 475 wheel HP.

Something that's a common misconception is that a casual start drag pass is hard on the car when in fact a few seconds threw the gears. It's not a big deal on a proper air fuel ratio. Its a few seconds not much different than a romp through the gears entering the freeway. Alternately more damage can occur from things like sustained hard load to store heat and particularly on a lean air fuel along with pinging. Throw in a cold new engine to start and wow. It happens not because people want to cause damage. Generically speaking many just don't know.

[ERA Chas]

Originally Posted by greg schroeder

The fuel thing is because I don't know too many people that take the time to buy the proper fuel for high performance cars. It's just too inconvenient for most.

No harm Greg. This is a true statement. I just can not condone encouraging a guy to make major and expensive changes to his engine because of 91 octane fuel.

My car is a second off your pace on 93 octane with 465 WHP, 200 more pounds and terrible for drag racing Hoosier T/Ds. Just couldn't put it down -1.9 60 ft. It took half as long to go the last 1/8 mile than the first. 121 MPH was a great top end charge though.

You made smart changes to your car and know how to feed it.

[RodKnock]

Originally Posted by RICK LAKE

Ps To Rod Knock, sorry for putting you to sleep with the long info threads. Just trying to give the best info, inside and outside the box. Does this mean I am not getting FRUIT CAKE for Christmas???

Rick, just kidding around, but it does take a long time to read your posts since they contain so much information. Not like my posts, which tend to have no redeeming value whatsoever.

[ERA Chas]

Originally Posted by RodKnock

Not like my posts, which tend to have no redeeming value whatsoever.

-but all of your posts have a certain lightness about them...

[RodKnock]

Originally Posted by ERA Chas

-but all of your posts have a certain lightness about them...

Substance weighs me down. And you know how I want to have a light car.