octane opinions on chip burn

[cathan]

I'm about to have a race chip burned for my fairly mild setup (see signature) with about 2800 stall.

The question is what octane should I have the chip burned for. I can get 110 leaded fuel at the track or 104 unleaded.

I do have the setup for leaded fuel tolerance....heated 02 and no cat.

I should also mention the track is at 5800 feet above sea level.
Probably no more than 20-22 lb boost I can't afford to break this thing.

It seems some say go hands down the highest octane possible, others say they mix 110 with 93, others say stick with unleaded fuel (why I'm not sure....)

.02's appreciated

Chris

 

[Razor]

Whats your experience tuning one of these cars?

Why not just keep your street chip and just up the octane and boost. Run your 104 and a 93 chip at 23-24 PSI boost. Monitor your knock.

See you throw timing at the motor.. it will want to knock.. if your not use to tuning one... dont throw timing. Timing should be added after you've become comfortable with what you have.

HTH

 

[77tech9]

You goto Bandy?

Maybe i'll see you at PMI during the Buick club race.

 

[cathan]

77tech9 .....yeah Bandimere it is.....looking forward to running this year because my car was not healthy last year. I'm hoping to make pueblo also.....If I plan ahead. (4 month old daughter.....)hope to see you....let me know how I can Identify your car. I will usually be found with my friend peter mandics who has a maroon 86 t-type.

Chris

 

[cathan]

Razor.....I guess from my question I made myself sound inexperienced, but I do have some experience with tuning these cars.

That said, the reason I posted the question is that I recently installed 50# injectors and opted for two chips, one for the street and one for racing.

I'm surprised you would recommend racing with a street chip, but I do understand you would tell a beginner to start by simply turning up the boost. I neglected to mention I have a scanmaster and can monitor knock....and the bald street tires are now drag radials.....

The decision was finally to go with a 104 burn and race it at 22-23 psi. My question is this, as far as head gaskets go: if I see no knock at even higher boost do I risk blowing them? IE, is head gasket failure most often due to knock?

I don't get to race alot as I have a four month old daughter, so I'm trying to get the most out of the car the few times I can with some degree of safety......

Thanks for your input

Chris

 

[77tech9]

Head gaskets will blow if there is a lot of knock, but knock could include, not enough octane, not enough fuel, etc, etc.

If you turn up the boost slightly each time and get no knock then you will be fine, once you see knock, dont go any more without more tuning.

Also, a lot of stock gaskets blow at really high psi too, like 30, but thats a chance you have to take.

 

[Razor]

well see what blows head gaskets is excessive cylinder pressure cuased by a multitude of things. Octane is number one, timing is two.. both which lead to detonation.

You get one of these motors and throw boost and timing, you are asking for power. Simple. If it rattles at high power, bad things can happen. And the more boost and timing.. the faster bad things can happen. A low timing chip affords a certain cushion of mistake. A high timing chip..your off in your "tune", there is a price to be paid.

If your comfortable with the O2's and knock the motor is running at, up the boost or up the timing.. eventually upping both.

While a scanmaster is ok, I typically recommend always starting conservative.. and moving from there. Once you break your car, you will have to pickup the pieces and move from there in experience. All of us that have broken our cars racing them, have a trail of bills and learning. My advice is stable no matter your level of mods.

Heres a recipe to break your car, get to the track, drop a high timing race chip in, with a mix of race gas and pump gas, up the boost 5-6 turns, pull up to the line.. let er rip and cross your fingers.

My way is get to the track and make a decision how much octane you have in the tank, adjust the boost, and run your lower timing chip.. shake the car down. Once the numbers are correct on the scanmaster, drop your race chip(from the same guy) and do a run at lower boost. If everything is ok.. then make your decisions on FP and boost and move from there methodically.

Its easy to rush and blow your motor up. Look at the Mustang guys.. Once you have your combo figured out... then record your readings(fp, wg rod,outside temps), and next time to the track you'll have your baseline numbers on the race chip and move from there.

HTH

If you plan on doing some racing, look into a direct scan or t-link to get a better handle of whats going on. Once the car is fully dialed in, then its not necessary.

Cheers

 

[XLR8]

Since we are over a mile high, a lot of the flat landers ideas don't work as well here. It has been my experience that a little extra timing can help. My "street" chip (I run 100UL) has 23* and I run 23# of boost. My race chip has 26* timing and I run 26# of boost using C116. I am thinking of having a new chip burned with 28* or 30* of timing to see how they work up here. Razor's advice is solid in that you should start with lower boost and walk it up 1# every pass keeping an eye on your 02 and KR readings. I'm going to try to go to Bandimere on April 121st for the day test and tune and I may stay for the evening.

 

[cathan]

Thanks for the replies guys.....Razor, I agree completely. Always better to start conservative than to pay the price....

XLR8.....I'll be there on the sunday apr 18th tech and test....hope to see ya

 

[77tech9]

How much do they want this year for T&T? It was getting pretty high down there.

 

[cathan]

Last year afternoon to evening test and tune was 30 or 35 bucks, and day tune was like 110.

As steep as the day tune is, I found it worthwhile to try and make it to one because the evening and weekend events get so darn crowded......

Chris

 

[ez at nova]

I have a similar gas availability situation, so in addition to my standard 93 chip,I picked up a 100 octane chip (for use with the GT104) and a 110 octane chip (for use with 110 or maybe 116). I sure like running that 100 on the street with 23 lbs of boost and 0 knock...but it gets pricey at $4.20 a gallon. Back to 94 I went for now.

 

[77tech9]

You guys need to look for another place to get gas

My 112 Leaded is only $3.25 a gal, but I run low boost on street with a 93 chip. And I usually mix the gas with pump.

 

[XLR8]

Last year test and tune night was $30 and you could enjoy the track with the other 400 cars. Day test was a steep $85, but, there were usually only 40 cars there and the kept the left lane for cars with race tires so there were no Hondas dragging water up to the line. Also they are a little lax on safety requirements during the day. I ran a handfull of 11.7's and didn't get booted. I ran a 12.03 at night and was talked to about getting close to needing upgraded safety equipment.

 

[77tech9]

What did they require after 11.99? Loop or cage?

 

[XLR8]

After 11.99 you need at least a bar, fire jacket, steel valve stems, long wheel studs and SFI seat belts. If I have enough money left after my trans gets rebuilt next week I am going to get the safety equipment. I am no longer young enough to think I'm invincable.