I recemtly had a 382 built for my car. Well the comp ratio is higher than id like and i get a little bit of real knock when in 5th or 6th gear. And knock when at WOT. If i add some heavy duty octane booster (offroad use) the knock will go away same as when running race fuel. So the knock is real.

With my Lunati stroker kit it brought the comp ratio to around 10.6.1 well add some heads milled about .40 and you climb into the iffy pump gas range. 11.5.1 and above.

So what could i do to combat? Thicker head gasket? I dont want to tear her down so soon.

What about a 160 deg thermostat and LS1 edit to change the fans? Right now i have a 178 deg thermo.

The new electric WP might help out.

Right now the car has 22 deg of total timing. It had no knock on the dyno but on the street i have knock.

HELP FELLAS!

 

And the 5 tanks of gas ive run with the heavy duty octane booster has kille one of my rear 02's already. There is only 1100 miles on this combo.

 

Hmm. You say knock in 5th and 6th only? No knock during full throttle runs? If you aren't seeing any knock during racing, I think you are ok. I'd put in a 160 thermo and use LS1 Edit to tune the knock out. After I put in the 230 cam I had some knock during 6th gear light freeway accels. I used edit to slightly reduce timing for those conditions.

How much knock retard are you seeing?

 

I have WOT knock on 93 octane.

 

Hate to say it but I think the 11.5 CR will plague you with knock as long as you run pump gas, better cooling will help only so much. I wouldn't run octane booster as it will kill your O2's. A thicker head gasked will definately lower your CR, but what a biotch to change out...

Dan

 

Why don't you compensate and bring the timing down until the knock disappears.

 

Its been brought down to 22 deg from 28!

 

Yes, but you're still getting knock. There are a few guys over here running 12:1 and above on pump gas with no issues. They just have a lower degree of timing. A lower T'stat will help a tiny amount. Any chance you're just getting shitty gas?

 

11.5:1 is really, too much for pump gas. At the sacrifice of HP you'll have to bring down the timing even more, along with tuning and cooling. A reverse flow electric water pump, not available yet I don't think, would help out quite a bit, IMO.

 

Ditch the octane boost in a bottle. Most of it is MMT, and thats garbage. Some of the octane boost is Toluene. You are looking at a .3 boost in overall octane. If you need to keep KR down, buy a gallon of Toluene or Xylene at the hardware store. Mix no more than 20% with your gas. On 5 gallons of pump gas with 1 gallon of Toluene you end up with 96 Octane or so....

Read the Rocket fuel FAQ:

http://www.gnttype.org/techarea/misc...explained.html


Also:

Richard Lassiter's "How to Mix Your Own Brew"
FORMULA 1
Toulene
R+M/2...114
Cost...$2.50/gal
Mixtures with 92 Octane Premium
10%...94.2 Octane
20%...96.4 Octane
30%...98.6 Octane
Notes: Common ingredient in Octane Boosters in a can. 12-16 ounces will only raise octane 2-3 *points*, I.e. from 92 to 92.3. Often costs $3-5 for 12-16 ounces, when it can be purchased for less than $3/gal at chemical supply houses or paint stores.
FORMULA 2
Xylene
R+M/2...117
Cost...$2.75/gal
Mixtures with 92 Octane Premium
10%...94.5 Octane
20%...97.0 Octane
30%...99.5 Octane
Notes: Similar to Toulene. 12-16 ounces will only raise octane 2-3 *points*, I.e. from 92 to 92.3. Usually mixed with Toulene and advertised as *race formula*.

FORMULA 3
Methyl-tertiary-butyl-ether (MTBE)
R+M/2...118
Cost...$3.50/gal
Mixtures with 92 Octane Premium
10%...94.6 Octane
20%...97.2 Octane
30%...99.8 Octane
Notes: Oxygenate. Very common in octane booster products. Has lower BTU content than toulene or xylene, but oxygenate effect makes the gasoline burn better and produce more energy.

FORMULA 4
Methanol or Ethanol
R+M/2...101
Cost...$0.60 - $1.75/gal
Mixtures with 92 Octane Premium
10%...94.3 Octane (Methanol)
10%...94.7 Octane (Ethanol)
20%...Not Recommended
Notes: Methanol is wood alcohol. Ethanol is grain alcohol and found in Gasohol in 10% ratios. Both alcohols are mildly corrosive and will eat gas tank linings, rubber and aluminum if used in excessive ratios. Main ingredient in "Gas Dryers", combines with water.

FORMULA 5
Isopropyl Alcohol and Tertiary Butyl Alcohol
R+M/2...101
Cost...$0.60-$1.50/gal
Mixtures with 92 Octane Premium
10%...94.5 Octane
20%...Not Recommended
30%...Not Recommended
Notes: Similar to Methanol/Ethanol. Isopropyl Alcohol is simply rubbing alcohol.


MAKE YOUR OWN OCTANE BOOST
How to make your own octane booster (this is the basic formula of one of the popular octane booster products). To make eight 16 ounce bottles (128 oz = 1 gal):

100 oz of toulene for octane boost
25 oz of mineral spirits (cleaning agent)
3 oz of transmission fluid (lubricating agent)

This product is advertised as "octane booster with cleaning agent *and* lubricating agent!". Diesel fuel or kerosene can be substituted for mineral spirits and light turbine oil can be substituted for transmission fluid. Color can be added with petroleum dyes.

 

Wow! I need to keep this for future reference

 

damn... good info Jrod.. no one local sells any 104 unleaded race gas for me either so i may make my own!

so i take I could just pour 1-2 gallons of Toluene into a 10gallon tank of 93? Is it that simple or would i need to mix it more?

 

That would give you a 10-20% concentration. I wouldn't go over 20% on Toluene or Xylene. But yes, thats all...

 

I'd get xylene if you can. It's more potent than tolulene.. you can get 5 gal buckets genreally at paint supply stores. call around. Also, marvel mystery oil is a good thing to add. It really helps to keep things lubed because tylene or xylene is very dry. One problem is that it (xylene or tolulene)does mess with your air to ful ratio a little(it leans you out a tad), so it's not ideal unless you're tuned for it, but it definitely helps in a pinch.
Bryan

 

I'd try going with an EWP along with a 160* stat and lower fan temps before lowering the CR.
DO NOT get tolulene or xylene on your paint because they are just the chemical names for lacquer thinner which is exactly what they are!! They will make a mess of your paint. I would NOT go mixing that stuff in my gas. I have the same Lunati kit as you with heads that are milled .030 . My max timing hits 29* and I do not have KR so I would look elsewhere to cure the problem. 1st thing is get a 160* stat andlower fan temps. I do not believe you CR is as high as 11.5:1 with your heads milled .040 More like 11:1

 

i ran alot of xylene thru my truck, probably close to 100gallons(30% mix)

here is what i found.

6psi 92gas, no KR
8psi 92gas, full 8deg of KR continuas
8psi 92gas+30%xylene, no KR
11psi 92gas+30%xylene, some KR at launch and shifts but not continuas.

i bet i could have ran 9 or 10psi with the xylene without KR. the stuff works. i did have one 02 sensor go bad but it had 50000miles on it so i am not sure if the xylene had anything to do with it. i also had a nitrous fuel seloniod go bad, that is when i started adding tranny oil to the mix, something like 3oz/gallon of xylene. i got it at a local paint store for $20/5gallon can and dumped it right in my truck.