Killer-Z

what plugs should i use for a 150 shot on my 91z? I heard I should use autolite 144's...is this true? Thanks Derrick

89ProchargedROC

i would go 1 stage colder plug

stock autolite number plug for us is 25 i believe....not sure i'm confused from the plugs i used.

just get the stock autolite plug number for our car and go 1 number down

Killer-Z

Does this mean you would recommend autolites?

Mikel

Use A/C delco. I don't have an IROC so I don't know the stock plug, whatever it is go one number colder for <150hp or so, and 2 colder for more than that. For example, if your stock plug is a R43TS, go to a R42TS for 100 shot and to a R41TS for a 200 shot.

89ProchargedROC

yes, use autolites

--when i had my blower i tried every plug manufacturer on the planet, you name it i tried it

autolite
ac delco
ac delco rapid fire
splitfire
NGK
blah
blah

tried many different heat ranges of each....autolites worked the best and many others use them here also and TONS use them in the N20 LT1 crowd with great results

wouldn't recommend anything else and they're cheap

F-BIRD'88

Look up the stock replacement plug for your car. Now look up one of the same type that
is 2 to 4 heat ranges cooler than stock. this is the right plug for nitrous.
EG. AC R44TS or R45TS is stock on a lot of late chevy heads with 5/8 hex tapered seat.
(peanutplug). for nitrous you would get
AC R42T or TS. A nonprojected tip plug
like the AC R42T gives a little more detonation projection than a projected tip
of the same heat range. The equivalent Champion would be RV8c or RBL9YC.
These plugs are cooler than stock but still fine for the street.

89ProchargedROC

2-4? no offense but that is way too cold unless he wanted to spray like a 200 shot, then i'd tell him about 2 stages colder

usually going any colder than 2 stages really hurts driveability and cold start on most cars and is just a band-aid for not lowering the timing like you should

F-BIRD'88

These are none too cold. These were stock plugs on 70's corvettes. When it comes to Nitrous, it's always better to be too rich or have a too cold (which these aren't) a plug. Retarding timing (up to about 180 HP) is just a band-aide for not using a quality gas (hi octane). The plugs recomended from
the factory for everyday use are even too hot for sustained full throttle use like road racing, without nitrous. I run a plug three sizes colder than stock, have had the same plugs for 2yrs and I don't have nitrous. Being a little too rich or having a little too cold a plug will not hurt any thing. But a lean out or detonation/preignition will destroy a motor in seconds. Most people try to run too much igition timing for max power anyways. 'Cause the "Butt-dyno" says it needs it.

[This message has been edited by F-BIRD'88 (edited November 07, 2001).]

89ProchargedROC

true, but most people wont run the gas with the big shot and it is safer to retard timing than rely on a colder plug to keep you safe....plugs can foul out really easy...timing wont do that

Also, i still think that 3 stage colder is TOO MUCH in HIS specific application. Every motor is different, maybe those are the plugs that work well for you, but if he runs plugs that cold, it is going to hurt his total power.

It is my opinion he only needs 2 stage colder of a plug otherwise the EGTs are going to be much lower and that means richer

F-BIRD'88

A cooler plug will never richen the mixture
or lower egt's it will only collect deposits
while at idle or light throttle. These are not racing plugs these's are street plugs.
Slightly cooler than stock. I've used these plugs to replace a stock plug on Hiperf Small blocks, Big blocks, built marine motors
Blower motors and street nitrous motors. With no idle fowling. Works on any thing that will be use in a "hi perf" manor. When grandma drives your car you need a hot plug...when you drive your car, foot to the floor, ya need a cooler plug than grandma. The stock plugs are for gramdma. cause most of the time we're putt-putting around. On a "big shot", I would never nor do they recomend retarding timing in the place of hi-octane gas. Excessive retard reduces power and heats the cylinder walls and increases EGT's. Better to reduce the amount of nitrous shot to match the available fuel and run more optimum timing and then tweek the nitrous/fuel ratio. I've seen 350+ hp added to a close to stock 302 mustang with cast pistons with no damage. Bracket racer.
The only problems he has is keeping the front wheels on the ground and burned up clutches. He runs full timing all the time. He runs the octane he needs. (race gas) Running a big shot(higher stage nitrous) and trying to tune around the need for better fuel, with anything more than minor ignition retard,is a slippery slope, will only get slightly better ET's and at the expense of engine life. This is how motors get destroyed on NOS. I know people try to do this (retard timing in place of proper fuel) then they go to higher shot of nos 'cause they aren't getting the power the think they should. Then they melt the motor or bend rods and wonder why. No wonder NOS won't answer their phone.... Just tring to keep the guy safe to start out. 2-4 sizes
is safe. he can always creap up 1 or 2 heat ranges later, but having to do a rebuild sucks.

[This message has been edited by F-BIRD'88 (edited November 08, 2001).]

Baz89RS

Also try looking for one that has a smaller ground strap, as I understad the stock longer ground straps tend to heat up to the point of glowing which then causes detonation...

F-BIRD'88

The tip of a thin electrode spark plug.
will overheat and glow faster than a conventional electrode. All else being equal. The only benefit that could have is it would burn off the electrode in the event of a leanout and stop the spark, therefore stop combustion and save the pistons. The proper heat range conventional plug will run at the proper temp while under power and not glow.

Killer-Z

If it is any help i will also be retarding my timing probly anywhere from 4-6 degrees...Later Derrick

jethro

here is the ideal setup:

5.7L engine can support a 150hp shot under sustained conditions with the following caveats:

1. Hi-flow fuel pump OR at a minimum a good fuel pressure gauge to continuously monitor pressure.
2. Hi-flow aftermarket fuel filter.
3. Adjustable fuel pressure regulator probably set between 48-50 psi.
4. Aftermarket ignition kit, new plug wires, new STANDARD plugs one to two ranges colder.
5. Some method of retarded timing... either the MSD system, nos dual prom holder, whatever... set at six degrees retarded for your 150hp kit.
6. The kit must be tied to WOT for activation.... MUST.
7. Never engage less than 2800 to 3000 rpm.
8. Always run 93-94 octane.
9. Hi-quality octane booster for the added protection of manganese... which is further insurance against detonation.
10. Bottle heater and nitrous gauge to monitor bottle pressure.

If you follow the above... you can run a nitrous system in your car absolutely, quaranteed SAFE... which is what we all really want, isn't it?



------------------
Jethro
1987 IROC Z 13.92 and 1.92 60' street tires stock engine

Kyle F

Try the R42LTS from A/C

------------------
89 Trans Am Turbo 3.8L All stock 43,000 miles #1053 of 1555

Past Thirdgen:
86 Trans Am w/ built 355TPI with SLP goodies and too much other stuff to List. One sweet *** car, wish I would have had a good enough Job to pay insurance on three cars so I could keep it, but for a 89 Turbo Trans Am w/ Low miles, I think I made the right choice!

F-BIRD'88

Don't waste your time with Any octane booster
that comes in a little can with lots of bright advertizing. There is no way a few oz's of tolene+ xolene+ mineral spirits and posibily MMT will raise the octane of a tank of gas. You will never see a professional race team use octane booster at any track, except maybe on TV. If you want to boost octane buy some 114 octane race gas and mix it with 94. or buy a gallon of tolene and a pint of acetone and throw that in the tank. You can buy a whole gallon in any paint store for $10. For 150 hp
on a 10:1 cr street motor all you need to do is fill up your gas tank with 100% 94 octane gas. Not 5 gallons. Don't believe me , do a search on the net for "FAQ's about Gasoline" it is written by a petroleum engineer. Not one brand of octane booster available off the shelf in USA or Canada has ever been able to raise a tank of gas more than 2 or three octane numbers and that is at 2x and 3X doses. You will probabily get away with a 150 hp shot of NOS by following these other posters recomendations, because 150 hp is a baby shot ,really so ya can't get in much trouble. But their tuning recomendations will not give you max hp and is risky at best. Save the little can of octane booster for your lawn mower and save your motor.
Run a plug 2 to 4 heat ranges cooler than stock, non projected tip if you can get them.
make sure you got a whole tank of 94+ octane gas. Make sure you have your fuel pressure right... 5 to 6 psi flowing on a wet system.
Follow the instructons for a dry system about fuel pressure. cause they vary.
Only retard timing 4 deg from normal.
"Normal Timing" on a small block is 32 to 36 deg total advance at hi rpm, not 38 or 40 or 46. *First* Burp the fuel with the nitrous off(bottle closed) to fill the line to the solenoid. While watching the fuel pressure gauge (it should drop to 5-6psi while the fuel is flowing. If it drops below 5psi find out why and fix it. Then run the motor at 3000 rpm in neutral and open the bottle and burp the nitrous and fuel in short burps of the switch till the nitrous catches. The motor will rev up when you burp it. You are now ready with a PRIMED nitrous system. Failure to do this simple operation at the start of a nitrous run can result in a nasty lean- backfire. right when you hit the button. (Lack of fuel.) Do not use a purge valve on first runs till you are sure of your tune up!Read the bottle pressure gauge. should be 800 to 850psi. If it's below 700psi do not run until you heat the bottle to 85Deg or 850 psi. Use hot water or a NOS bottle heater with a shut off switch. Make a run engaging the NOS at 3000 rpm. If you hear any thing like rattling, knocking, backfire or anything other than a smooth but powerfull increase in power. GET OFF THE NOS and GET off THE GAS pedal. Stop and fix it. If all is normal you can stay on the NOS and shift at the same rpm for normal runs. Now stop and pull out 8 (eight) spark plugs.
You are looking for danger signs. Over heated electrode Bluey white or burned. (lean mixture.). any damage to electrode or porcelin black or silver pepper spray on porcelin. (detonation)
Black porcelin (rich fowling) not likely. Any sign of a lean mixture must be corrected.
If nessessary add 1/2 lb of fuel pressure.
If you set it up right every thing will look normal and the run will be smooth but powerfull.If every thing is normal add 2 deg of timing. and test again. If the car runs faster MPH this time and everything is normal. you can advance timing 2 more deg.
This should get you back to normal ignition timing 32 to 36 total No more. Make another run the same and check plugs again. AS long as you heard no detonation or backfireing
or see any danger signs on the plugs and your MPH didn't drop. YOU are at OPTIMUM IGNITION ADVANCE for 150HP NOS. IGNore the color of your plugs as long as they are not overheated or damaged or black porcelines..Your 10LBS
of NOS will be just about gone now. It will have some nitrous still in the bottle but the power will decrease some on future runs till its empty. So in other words do not try to tune a NOS system with a half empty bottle or a cold bottle, cause when you try it again with a full bottle u could get a nasty suprise.
Here's some notes. Make sure your air/fuel ratio (carb jetting ) and timing (32 to 36 total) is correct for N/A runs first. Use new plugs. Old plugs will Fowl and fail the first time you try the bottle cause they have old deposits on them and that will glaze the plugs. It is not unusual for a motor to fowl the plugs the first time Nos is tried on it. Nos will clean out your combustion chambers of all deposits and carbon big time. Instant tune up. If these deposits or carbon that was sitting on your pistons hit your plugs they will fowl the plugs. The only remedy is to change all the plugs with new ones. The good news is: once this happens once (carbon fowled plugs on first NOS test) your motor will be nice and clean inside and it won't happen again. So bring an extra set of new plugs the first time.... trust me on this one , save ya a long walk home... If you have more than 10:1 cr or want to inject more than 180hp shot of nos GET RACE GAS. Forget the octane
booster and forget excessive fuel dumping and forget Un-nesessary ignition retard. A few deg is ok while testing your new set up. On big shots of nos the burn rate gets faster so retard is called for. But never in the place of high octane fuel. This is a safe and powerfull 150 hp NOS tune up. If you follow it to the letter and follow the instructions for your NOS system you will have lots of fun, go fast and not hurt your motor... If any of this confuses you in any way, stop ask questions, re-read it or phone your nitrous company and ask.


[This message has been edited by F-BIRD'88 (edited November 09, 2001).]

[This message has been edited by F-BIRD'88 (edited November 09, 2001).]