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1984rampage
01-20-2015, 11:16 AM
I have an 89 Omni that is being converted to MPFI and will then be sprayed.

In your experience, what would be the highest shot of nitrous I can run on the stock 89 TBI bottom end ?

What sort of AFR should I be tuning for when running nitrous ?

What are the bare minimums for setting up a reliable system ? (WOT switches, window switch, push button ?)

Any tips for a first time nitrous user ?

contraption22
01-20-2015, 12:02 PM
I have an 89 Omni that is being converted to MPFI and will then be sprayed.

In your experience, what would be the highest shot of nitrous I can run on the stock 89 TBI bottom end ?

What sort of AFR should I be tuning for when running nitrous ?

What are the bare minimums for setting up a reliable system ? (WOT switches, window switch, push button ?)

Any tips for a first time nitrous user ?

Seek out turbo-mopar member "zin". He's the resident nitrous expert and very willing to share his knowledge.

zin
01-20-2015, 01:17 PM
Speak of the devil?...:p

Best tip for a first time user is to not get carried away, which is very easy to do!

You'll have to decide what type of system you'll want to run, direct port, or single point (often referred to as a "wet" system). The TBI intake is designed to have fuel go through it, so a "wet" system is ok, the only real problem will be distribution to four ports from one injection point. Mounting the nozzle up as high as is likely practical should help in this regard.

As for controls, run, at a minimum, an arming switch, and a full throttle switch. If the car is a stick and you're prone to bogging it, a RPM switch would be a good idea, as it will prevent the system from coming on at too low of a RPM, which can cause damage due to the high pressure such a high concentration of nitrous can produce.

There are lots of "goodies" that you can add to any system, but most aren't going to be a requirement in order to actually use the system, most are convenience items or things that make the system more "automatic"/consistent.

If you choose to use a RPM switch, I'd suggest looking at the NOS mini-Controller, it has a RPM window switch built in, can trigger off the TPS signal and ramps in the power however you set it to, and for less than $250.00... Some RPM switches will cost more than that by themselves.

As to AFR. 12.5:1 is a good starting point, but a little richer is ok, so long as you're not getting a lot richer. If you want/need to dial things in closer, you'll need to read the plugs, I don't trust sensors to give me the whole story when things get a bit more "critical".

Speaking of critical, the most critical aspect of a nitrous tune-up is going to be ignition timing and fuel, due to detonation concerns. As for fuel, run the best you have available. As to timing, retard it from where the engine runs its best on its own about 1.5-2* per 50HP added. This is a safe starting point, often engines will like a bit more timing than this, but running "too little" timing will only kill power, not engine parts!

Now for the $10K question... "how much can I run?"... You can "pill it up until you sweep it up, then back it off a bit", or keep it to about 40-50% of what the engine was designed to make from the factory. Most engines are "over-built" enough to handle that amount of added power, some can handle much more, some not so much, but those are fairly rare, and not in the Mopar universe thankfully.

Feel free to ask if I've left something out that you are curious about.

Mike

ATaylorRacing
01-21-2015, 11:04 AM
When I was first using nitrous I was having lots of breakage...melting. I found what I think is the BEST tuning tool in the way of a large digital EGT gauge with highest memory. I have found that both my turbo and carb cars ran the most consistent when the max EGT at the finish line is 1390 degrees. You MUST have a capable fuel pump because with higher nos jetting most stock pumps...and some aftermarket pumps will not be able to keep up. The best way to prepare before nos is make sure everything works as it should all the time...then use the EGT gauge to see where you are at after a 1/4 mile pass. After putting the nios set up on make sure your EGT readings are the same, or even lower.
Back in the early 90's I had a Omni GLH turbo with the old over the motor and through the hood intercooler. It pulled a max of 14 psi (using a bleed) and ran 14.0s...about 200 hp. The bleed I used had two valves on it so when I was ready to use nos I would lower the boost to under 12 psi because using the spray would raise the boost. Sometimes it was noted that I ran a 175 hp shot...wrong, 150 was the most I successfully ran...good enough to run an incredible (back then) 11.89! I must mention that when not using nos I would leave in 1st gear (full manual valve body on an automatic trans) but the 20" slicks were unable to hook when spraying...until I started leaving in 2nd! Having only one shift through the 1/4 helped make that car very consistent. The 60" times were much quicker leaving this way compared to spinning off the line. The GLH was not the only car I used it on.
1990 Dodge Shadow with S60 set up...12 teens...11.9s with 50 hp shot
1998 SOHC Plymouth Neon 5 speed...14.8s on motor...12teens with 125 hp shot...20" slicks BUT leaving in 1st gear
1999 Miata MX5 ran 15.8s on motor...12.65 at 109 with 100 hp shot and leaving in 2nd with a 5 speed and 20" slicks
I always tried to run less hp than the max that the stock block/stock internals could take...never ran aftermarket internals. NEVER had any issues after learning how to use the EGT for tuning.

- - - Updated - - -

Forgot to mention that I always used an arming switch and always used a button on the left side of my steering wheel to operate it.

1984rampage
01-23-2015, 05:56 PM
Speak of the devil?...:p

Best tip for a first time user is to not get carried away, which is very easy to do!

You'll have to decide what type of system you'll want to run, direct port, or single point (often referred to as a "wet" system). The TBI intake is designed to have fuel go through it, so a "wet" system is ok, the only real problem will be distribution to four ports from one injection point. Mounting the nozzle up as high as is likely practical should help in this regard.

As for controls, run, at a minimum, an arming switch, and a full throttle switch. If the car is a stick and you're prone to bogging it, a RPM switch would be a good idea, as it will prevent the system from coming on at too low of a RPM, which can cause damage due to the high pressure such a high concentration of nitrous can produce.

There are lots of "goodies" that you can add to any system, but most aren't going to be a requirement in order to actually use the system, most are convenience items or things that make the system more "automatic"/consistent.

If you choose to use a RPM switch, I'd suggest looking at the NOS mini-Controller, it has a RPM window switch built in, can trigger off the TPS signal and ramps in the power however you set it to, and for less than $250.00... Some RPM switches will cost more than that by themselves.

As to AFR. 12.5:1 is a good starting point, but a little richer is ok, so long as you're not getting a lot richer. If you want/need to dial things in closer, you'll need to read the plugs, I don't trust sensors to give me the whole story when things get a bit more "critical".

Speaking of critical, the most critical aspect of a nitrous tune-up is going to be ignition timing and fuel, due to detonation concerns. As for fuel, run the best you have available. As to timing, retard it from where the engine runs its best on its own about 1.5-2* per 50HP added. This is a safe starting point, often engines will like a bit more timing than this, but running "too little" timing will only kill power, not engine parts!

Now for the $10K question... "how much can I run?"... You can "pill it up until you sweep it up, then back it off a bit", or keep it to about 40-50% of what the engine was designed to make from the factory. Most engines are "over-built" enough to handle that amount of added power, some can handle much more, some not so much, but those are fairly rare, and not in the Mopar universe thankfully.

Feel free to ask if I've left something out that you are curious about.

Mike

Awesome advice. Thanks !

I am ditching the TBI setup for a stock 1-piece MPFI setup. If I were to go with a wet kit and a single nozzle, where should I place it ?

With timing, should I just reduce timing via the distributor, or is it beneficial to reduce the timing at WOT only via the calibration ?

- - - Updated - - -


When I was first using nitrous I was having lots of breakage...melting. I found what I think is the BEST tuning tool in the way of a large digital EGT gauge with highest memory. I have found that both my turbo and carb cars ran the most consistent when the max EGT at the finish line is 1390 degrees. You MUST have a capable fuel pump because with higher nos jetting most stock pumps...and some aftermarket pumps will not be able to keep up. The best way to prepare before nos is make sure everything works as it should all the time...then use the EGT gauge to see where you are at after a 1/4 mile pass. After putting the nios set up on make sure your EGT readings are the same, or even lower.
Back in the early 90's I had a Omni GLH turbo with the old over the motor and through the hood intercooler. It pulled a max of 14 psi (using a bleed) and ran 14.0s...about 200 hp. The bleed I used had two valves on it so when I was ready to use nos I would lower the boost to under 12 psi because using the spray would raise the boost. Sometimes it was noted that I ran a 175 hp shot...wrong, 150 was the most I successfully ran...good enough to run an incredible (back then) 11.89! I must mention that when not using nos I would leave in 1st gear (full manual valve body on an automatic trans) but the 20" slicks were unable to hook when spraying...until I started leaving in 2nd! Having only one shift through the 1/4 helped make that car very consistent. The 60" times were much quicker leaving this way compared to spinning off the line. The GLH was not the only car I used it on.
1990 Dodge Shadow with S60 set up...12 teens...11.9s with 50 hp shot
1998 SOHC Plymouth Neon 5 speed...14.8s on motor...12teens with 125 hp shot...20" slicks BUT leaving in 1st gear
1999 Miata MX5 ran 15.8s on motor...12.65 at 109 with 100 hp shot and leaving in 2nd with a 5 speed and 20" slicks
I always tried to run less hp than the max that the stock block/stock internals could take...never ran aftermarket internals. NEVER had any issues after learning how to use the EGT for tuning.

- - - Updated - - -

Forgot to mention that I always used an arming switch and always used a button on the left side of my steering wheel to operate it.

EGT sounds interesting. Will definitely pick up an EGT gauge when I start tuning.

Goal is mid 13's in the omni at something above 100mph.

Think its doable ?

ATaylorRacing
01-23-2015, 06:37 PM
Very doable...lets say the total wt of the car and you is 2500 lbs you should be able to run 13.50 with about 203.3 hp at the tires.

I cant remember the EGT gauge I currently use...but looks like this one:
http://rjcracing.com/product/egt-gauges/
Might be this one....?
http://www.ifamilysoftware.com/8515.html

I wasted money a couple of years when the ones I bought would have troubles
on the probe where it plugs into the gauge.

ATaylorRacing
01-23-2015, 06:46 PM
Matchbox has NEVER had nitrous on it...but currently has a bit over 106 non-turbo hp...but with its 1895 wet wt and my 215 clothed wt only 176 hp would let me run 13.5 compared to the 15.7s it runs now.

zin
01-23-2015, 07:35 PM
Awesome advice. Thanks !

I am ditching the TBI setup for a stock 1-piece MPFI setup. If I were to go with a wet kit and a single nozzle, where should I place it ?

With timing, should I just reduce timing via the distributor, or is it beneficial to reduce the timing at WOT only via the calibration ?

Well, the way to "have your cake and eat it too", is to have the timing reduced only when the system is active. If you are doing your own cals, especially if you are using Rob's "Turbonator" code, it is possible to do just that, and in fact you can add the fuel via the injectors. This is the ideal way to inject nitrous, fuel right at the valve, nitrous upstream of the throttle body.

If the "ideal" isn't possible, the next best/most common way of doing it will be to turn the timing back at the distributor as this will have the same affect as any other means, and install the Fogger about 6-8" away from any bends in the intake tract. The "fog" comes out pretty concentrated and hard for about that distance and so won't like making a turn, which is just what we need it to do, as well as "split up" to go down four different holes.

Normally I'd say install it just after the intercooler on a stock TII set up, your situation will be a little more unique, but easy enough I suspect.

Mike

acannell
01-23-2015, 08:11 PM
Very doable...lets say the total wt of the car and you is 2500 lbs you should be able to run 13.50 with about 203.3 hp at the tires.

I cant remember the EGT gauge I currently use...but looks like this one:
http://rjcracing.com/product/egt-gauges/
Might be this one....?
http://www.ifamilysoftware.com/8515.html

I wasted money a couple of years when the ones I bought would have troubles
on the probe where it plugs into the gauge.

I make a very powerful EGT gauge with two inputs, gauge style mounting, and peak hold features. It also has a difference function which lets you observe the real time difference between the two probes, as well as peak detect the difference (difference is good for analyzing across components like intercoolers, turbos, etc..). Basically I made it because everything else out there (and I mean everything..I looked), was either too slow, ridiculously expensive, had a limited range, no difference function, etc..etc.. basically its like the people who designed the EGT gauges out there figured they could make junk and sell it at a price 3 times higher than what laboratory equipment costs, but with very inferior specs. Oh and mine has two analog outputs too that could be connected to a datalogger or even an ECU for special triggering on temperature.

BTW the price is not $200 its $175

http://www.exoticelectron.com/dtgauge.html

OmniLuvr
01-23-2015, 10:06 PM
what about using the "direct port" nozzels that go "under" the fuel injector? just an option...

I think (no expert) that some of the damage caused by nitrous is the instant tq spike it produces at low rpms, low rpm high tq is what can break parts. so like mike said, something like a nitrous controller that can pulse a duty cycle to the solenoid that can ramp up the "hit" slowly as rpms get higher to aid in traction and save parts. the kicker is I would run a very large/lopey cam and higher compression (nitrous likes compression) to hopefully give you some higher rpm hp.

bakes
01-23-2015, 11:11 PM
just so you know there is a nitous retard function in the latest turbonator Cal

ShadowFromHell
01-24-2015, 01:44 AM
I really like the EGT tunning idea. A LOT lol. It's so simple but effective. I've got a kit I bought years ago but have always been afraid to use it. Just didn't feel safe, especially since it'd always been "let's throw nitrous on the DD cause the fast cars are all broke" lol. Do you think a WBO2is even needed if you use the EGT method? I've ran EGTs on my turbo cars but never trusted then, but I've since found out was causing those problems.

shadow88
01-24-2015, 05:27 AM
Personally, I use a wide band to fine tune the engine first, then a knock sensor output to fine tune the ignition advance. THEN back off 3 degrees base and fine tune the nitrous system to a full point richer (11:1 ) for my engine.

Only two failures ever when using nitrous. First was caused by not reading the wide band, that was telling me there wasn't enough fuel, the second failure was the wide band reading incorrectly after 3 years and some coolant passing by from a popped head gasket.

Your results may differ, as well as your 1/4 mile times, there's lots of practice, grip, track prep and driving experience that all have to factor in.

ATaylorRacing
01-24-2015, 07:34 AM
I make a very powerful EGT gauge with two inputs, gauge style mounting, and peak hold features.....
BTW the price is not $200 its $175

http://www.exoticelectron.com/dtgauge.html

Wow....a unit that you can put into your dash and wires to the car! The ones I have used for many, many years are examples of the ones I linked to and use a 9 volt battery. I have saved your link and when I need my next one or am asked I will come to you or suggest you!