100 Dry Shot on Stock pump/injectors/etc..

[BobDoLe]

I know the general concensus is to upgrade elements of the fuel system (fuel pump for example) before going past a 75 shot and into the 100 dry shot territory.

Why is that?

The obvious answer would be that the pump would not be able to keep up and the car would start running lean.

Well I'm thinking of attempting the 100 dry shot on the dyno in the next week.

My plan is to put the car on the dyno without nitrous, then with the 75 shot and monitor a/f ($95 for 3 pulls and a/f ratio).

If the car feels like it could handle the 100 shot, I'm thinking of throwing it on there and monitoring how it does with it.

I know someone else must have tried this before. Is the danger that the pump just wont be able to push enough fuel and I'll run a bit lean? Or is the danger that the pump will fail at some point because it is being pushed too hard?

What are your thoughts/predictions on this?

[97rs4life]

Re: 100 Dry Shot on Stock pump/injectors/etc..

fuel pump not keeping up with required fuel needs is one, the other is your injectors not being able to supply enough fuel and you max them out. Going lean will be the biggest problem to worry about here.

[UDLOSE98]

Re: 100 Dry Shot on Stock pump/injectors/etc..

You risk running the motor way too lean and snapping a rod, blowing a head gasket, why try throwing the other 25 at it if you are running the risk of it being unsafe, you already will know what to expect anyways. which is approx.....oh i dunno 25 hp???

[Shodown]

Re: 100 Dry Shot on Stock pump/injectors/etc..

Would you try to run through a busy intersection in the middle of rush hour just to see if you could survive? Maybe you could, but why try?

Why would you deliberately do something when you know the consequences? Get what I'm saying?

25 hp is not worth it. Even when monitoring the A/F ratio wont help, if it runs too lean for less than a second...KABOOM! Game over brother.

Its not that the pump would fail, its that it would be maxxed out not giving the injectors the right amount of fuel to the cylinders.

[Camaro Dom]

Re: 100 Dry Shot on Stock pump/injectors/etc..

i'm surprised they'll let you even try that... i've heard horror stories of how superchargers have blown thru hoods from running lean...

[Shodown]

Re: 100 Dry Shot on Stock pump/injectors/etc..

^^The dyno shop doesnt give a dam what you do. They could care less that your are running purposely, they just want their $100 and hour.

[usd2sing]

Re: 100 Dry Shot on Stock pump/injectors/etc..

something else to consider:

using the shops stinger wideband (insert into tail pipe) will not give u an accurate reading.

you will be leaner on the street vs the readings from a stinger at a dyno.
on the street/road you have more air "flowing". shops use large fans but its not enough to simulate actual street driving.

other neg is that the stinger reads after the cat (if equiped), more false readings.
last neg is the stinger is in the last section of your exhaust. thats to far away from what the motor is generating by the time it reads the afr it may be tooooooo late!

dyno wb's are good for checking things out. most shops worth thier salt will install a bung infront of the cat and install thier sensor in that location. better, more accurate readings.

FWIW

[lilchubby]

Re: 100 Dry Shot on Stock pump/injectors/etc..

i am currently running a 100 dry shot on a stock fuel system. my only advise for this is to make sure u have some sort of air fuel gauage to keep an eye on things. i constintly watch the guage while im spraying and am acutally still running a bit rich when spraying. but like they have said its possible for things to go wrong. i found a whole new love for my nitrous after the 100 shot, and wouldnt dare go back down. baisically it comes down to a car by car bases. just watch what ur doing and keep an eye on things. if it looks like its even starting to get close to lean let out. never know till u try.

[Shodown]

Re: 100 Dry Shot on Stock pump/injectors/etc..

You're walkin a line there Chubby! Flirtin with disaster! :D

Just be careful, I hate reading posts of people blowin up motors on spray then hearing others bad mouth nitrous because of it. Not to mention I would hate for you to damage you're motor. :)

[BobDoLe]

Re: 100 Dry Shot on Stock pump/injectors/etc..

i am currently running a 100 dry shot on a stock fuel system. my only advise for this is to make sure u have some sort of air fuel gauage to keep an eye on things. i constintly watch the guage while im spraying and am acutally still running a bit rich when spraying. but like they have said its possible for things to go wrong. i found a whole new love for my nitrous after the 100 shot, and wouldnt dare go back down. baisically it comes down to a car by car bases. just watch what ur doing and keep an eye on things. if it looks like its even starting to get close to lean let out. never know till u try.

Awesome!

Tell me a few things;
What gauge setup are you using? Wideband sensor with A/F gauge? Pyrometer?
What is your bottle pressure? Are you using an automatic heater?
Where is your dry nozzle placed?
How many bottles have you been running like this?

I'm almost certain you are able to do this due to your environmental conditions. I checked weather.com and it looks like Scottsboro has been seeing late 80's temperatures with very high humidity.

It seems like you're the only person who has done this on this forum (unless anyone else wants to chime in with a horror story that happened with their 3800 on 100 dry shot). At the same time, I am feeling that maybe the 100 shot isn't such a great idea for me - it is a risk that I don't really need to take even though you may be showing me that it isn't all THAT risky.

Let me ask another question about dry shots...
If the dry kit is rated at 75 rwhp with the bottle at 950psi, what happens if I keep the bottle at 1050-1100psi? What sort of increase should I see?

[AZ3.8Camaro]

Re: 100 Dry Shot on Stock pump/injectors/etc..

I also ran a 100 shot on a stock fuel system.
Make sure you have a FPSS and you will be ok.
My fuel pump did go out after the first bottle, but not while I was spraying, the car just got harder and harder to start.

[lilchubby]

Re: 100 Dry Shot on Stock pump/injectors/etc..

im currently just using a stoichometer(a/f ratio guage). im running with a cold fusion bottle heater with no thermo in it, so i just run it until i think its hot enough. i try to spray above 900, and have done it all the way up to like 1250. my nozzle is right in the neck of my whisper lid, and have have went through 2 bottles without a problem. anything else i can help you with, just let me know. oh and as for the weather, i have sprayed the 100 shot on cool nights, somewhere int he 80's, as well has hot days temps in the mid 90's. hope this helps, forrest.

[BobDoLe]

Re: 100 Dry Shot on Stock pump/injectors/etc..

Thanks!

I'm running the 75 shot at around 1050-1100 psi. I took it as high as 1200 and it felt like my neck was going to break. I read somewhere that when you up your bottle pressure like that, you are putting down a lot more horsepower than what the jets were rated for (ON A DRY SHOT). For example, a 50hp (DRY) shot at 1200psi is argued to make more horsepower than a 100hp shot at 800psi. I have no idea how valid that argument is, but running that 75hp shot at 1200+ psi was intense. I would do it again, but I believe that increasing the bottle pressure like that will nuke my motor for sure.

Any thoughts? Is it safer to run a 75 shot at 1200 psi or 100 shot at 950 psi?

I've been effectively talked out of my attempt to run a 100 shot (thank you) for now.

[lilchubby]

Re: 100 Dry Shot on Stock pump/injectors/etc..

i really dont see why to much bottle pressure would matter. i know to little and you arent getting the full shot. it dont matter how much ur pressure it still only lets the same amount of spray through. im sure its just consistantey of the shot makes the differance. having enough pressure just keeps the shot from cutting in and out. im sure it makes it feel like it hits harder though. what turned u against it all the sudden. dont get me wrong i know its a risk, but a calculated one. as long as u take the saftey procautions you could stop anything major from happening.

[BobDoLe]

Re: 100 Dry Shot on Stock pump/injectors/etc..

It's a money thing for me. In the Bay Area, cost of living is high. I can gamble with this engine to an extent, but if I do lean out and blow it up, I am in a world of hurt. The cost to rent a closet sized studio here is the same cost as a mortgage payment for a 4 bedroom house in pretty much any other state. Ultimately, it is a money concern. If I can get a wideband O2 hooked up with an A/F gauge, I would risk it. The dyno shops here do use the sensor in the tailpipe, so I am skeptical about a/f readings that I absolutely need to be accurate. I'm on my third bottle of the .044 (75hp shot) jet and I have been experimenting with increased bottle pressure. 950psi and 1100psi is a HUGE difference. When I run the .044 jet at 1100psi, I do not want to increase the jet size because I already feel like upgrading suspension, driveline, etc just to keep up with the power.

I think the bottle pressure does matter as it affects the state of the N2O as it shoots through the jets. I am not 100% sure, but I know that you know there is a huge difference between 900psi and 1100psi on the same jet. If our HSW Sudden Impact kits are rated at 950psi and we can feel a significant increase in power by increasing the bottle pressure, we are no longer working within conditions that produce 75HP with a .044 jet.

I finally got a cardomain account.
http://www.cardomain.com/ride/2445423/