How big of a shot on a 370 w/ Probe -16cc dished pistons?
02-25-2010, 12:22 PM
#23
I wouldn't worry about the stock crank. I've hit mine with 400 before and I have seen more than one car make well over 700rwhp with the stock crank. The progressive will help take the hard initial hit off the crank too.
Like JL-WS6 said, some cylinders are known to run different than others but personally I would start out with the same jets in every hole just to get a baseline. Some are worse than others, some don't have any problems at all, either way I would run the same jetting all the way around just first, then read your plugs and go from there.
Are you running a low pressure setup or high?
The tune up is the biggest factor in how much you can spray on it. If you don't know how to read plugs and know what to do to to make the correct changes then you shouldn't spray anymore than 200 or so. If you do know what you are doing or you have an experienced tuner that has dealt with big shots of nitrous then the sky is the limit.
Make sure to read your plugs and pull plenty of timing, especially when you first get started.
Like JL-WS6 said, some cylinders are known to run different than others but personally I would start out with the same jets in every hole just to get a baseline. Some are worse than others, some don't have any problems at all, either way I would run the same jetting all the way around just first, then read your plugs and go from there.
Are you running a low pressure setup or high?
The tune up is the biggest factor in how much you can spray on it. If you don't know how to read plugs and know what to do to to make the correct changes then you shouldn't spray anymore than 200 or so. If you do know what you are doing or you have an experienced tuner that has dealt with big shots of nitrous then the sky is the limit.
Make sure to read your plugs and pull plenty of timing, especially when you first get started.
02-25-2010, 12:41 PM
#25
You can start off with the same jets, the offset I'm mentioning is what you'll probably find it will need, I should have been more clear on that.
Low pressure for sure, with a cheap holley regulator. You try to run high pressure, and the fuel jets are so small that they clog really easy, and you'll have to check them literally almost every time you spray... big pita. Low pressure, say 5 to 6 psi, and you can get away with alot less maintenance, just have to flow the fuel system each day at the track, really should do it a few times, get used to adjusting the pressure and what the weather does to the fuel flow as well.
Low pressure for sure, with a cheap holley regulator. You try to run high pressure, and the fuel jets are so small that they clog really easy, and you'll have to check them literally almost every time you spray... big pita. Low pressure, say 5 to 6 psi, and you can get away with alot less maintenance, just have to flow the fuel system each day at the track, really should do it a few times, get used to adjusting the pressure and what the weather does to the fuel flow as well.
02-25-2010, 12:52 PM
#26
Is there a good book out there I can pick up that covers all this? When you say flow the fuel system do you mean just activating the pump and setting the regulator? So 5lbs is a good pressure? How low is safe? I appreciate all the help as well. Thanks.
02-25-2010, 03:09 PM
#27
My advise, and I know that the sponsors are gonna probably get all over me for this, but I'd look up induction solutions, or monte smith performance, and see if you can send either one of them the intake to have it flowed, have them set you up with a matched st of jets, and go over the tuneup with you.
I'm gonna say, that if you want to say spray a 30 jet of nitrous, which is about 275 hp worth, you will need to pull a good 12 degrees from your n/a tuneup (say you're at 24 degrees, pull it back to about 12 degrees, and this is a starting point), put a #10 plug in the car for the first hits, with a NGK non protruded tip, and you will need to make 1/8th mile hits and read the plugs, click the key off and pull them all, and check every cyl... as for the fueling that depends on the jet spread. With a 4 jet spread (say a 30 nitrous, 26 fuel) I'm going to say that about 5.5 psi of folwing fuel pressure thru a flow tool with a .071 jet in it will be a starting point that shouldn't be too far off, providing your n/a tune is right.
I'd call one of the above guys because they are the ones that are setting up alot of race cars, and can get you a tuneup to start. What I posted above is probably close, but they can get you in the right direction.
Don't get me wrong, HSW and Nitro Dave's can help you out and can get you in the right area, but when you want to start spraying a big hit you need to know what you're doing and the guys I mentioned are at the track every weekend with fast cars, and have a good handle on what plugs should look like, what to do if something isn't right, etc.
I know Dave's built a bunch of fast running stuff, and Harris has some cars out there with their stuff and I wouldn't hesitate to buy from either of them.... I just know too many people that have used my 2 sources with alot of good luck.
I have Ken from eastside performance as well that I can get alot of help from, and he's taught me a TON about what a car needs to be right, safe and fast... he's been around the racing end of stuff forever as well.
As for a book to read, I don't know if there is one. Best bet, is to start small and work your way up, slowly, and plan on going thru and cutting up ALOT of spark plugs before you have a good handle on what the motor wants/needs, and what changes you need to make for weather, etc.etc.
If it was easy to spary 350 to 400 hp of nitrous everyone would do it.
I'm gonna say, that if you want to say spray a 30 jet of nitrous, which is about 275 hp worth, you will need to pull a good 12 degrees from your n/a tuneup (say you're at 24 degrees, pull it back to about 12 degrees, and this is a starting point), put a #10 plug in the car for the first hits, with a NGK non protruded tip, and you will need to make 1/8th mile hits and read the plugs, click the key off and pull them all, and check every cyl... as for the fueling that depends on the jet spread. With a 4 jet spread (say a 30 nitrous, 26 fuel) I'm going to say that about 5.5 psi of folwing fuel pressure thru a flow tool with a .071 jet in it will be a starting point that shouldn't be too far off, providing your n/a tune is right.
I'd call one of the above guys because they are the ones that are setting up alot of race cars, and can get you a tuneup to start. What I posted above is probably close, but they can get you in the right direction.
Don't get me wrong, HSW and Nitro Dave's can help you out and can get you in the right area, but when you want to start spraying a big hit you need to know what you're doing and the guys I mentioned are at the track every weekend with fast cars, and have a good handle on what plugs should look like, what to do if something isn't right, etc.
I know Dave's built a bunch of fast running stuff, and Harris has some cars out there with their stuff and I wouldn't hesitate to buy from either of them.... I just know too many people that have used my 2 sources with alot of good luck.
I have Ken from eastside performance as well that I can get alot of help from, and he's taught me a TON about what a car needs to be right, safe and fast... he's been around the racing end of stuff forever as well.
As for a book to read, I don't know if there is one. Best bet, is to start small and work your way up, slowly, and plan on going thru and cutting up ALOT of spark plugs before you have a good handle on what the motor wants/needs, and what changes you need to make for weather, etc.etc.
If it was easy to spary 350 to 400 hp of nitrous everyone would do it.
02-25-2010, 04:25 PM
#28
I already called Nitrous Outlet and they are going to re-install everything for me and flow it. It came all disassembled when the Fedex truck dropped it off yesterday. They aren't charging me a whole lot for the re-install and flow since they originally did the setup. I'm also going to have to get new fuel rails and have them install those as well. That way I just have to bolt it on and go. Do the test passes at 1/8 mile like you recommend and figure things out. What tool do you use to cut the plug apart at the track?
02-26-2010, 04:41 AM
#31
I don't like mixing fuels, that adds a whole different dynaic to tuning the car.
lowest shot you can go with on a fogger/dp? I dunno, smallest I have ever seen anyone go was a 24 jet, and that was a 24nitrous, 20 fuel, and they were running around the 5 psi of fuel mark.
I'd start off with a 26/22 and go up from there, that's a decent power gain, but not too much so that you're going to hurt stuff on the first pass if it's not right. (well you could it its WAY off, but you should be able to get it close)
Remember, take your n/a tune (go to track, run it on motor and add timing until it doesn't gain any mph then back it off a degree or 2 for optimal n/a timing) and pull 1 degree for every 25 hp plus about 3 more, so example, if you are running say 26 degrees n/a, and want to put 200 hp of jet to the car, start with 11 degrees out. That should be close, your compression being as low as it is will let you run a couple more then a guy running alot of compression.
lowest shot you can go with on a fogger/dp? I dunno, smallest I have ever seen anyone go was a 24 jet, and that was a 24nitrous, 20 fuel, and they were running around the 5 psi of fuel mark.
I'd start off with a 26/22 and go up from there, that's a decent power gain, but not too much so that you're going to hurt stuff on the first pass if it's not right. (well you could it its WAY off, but you should be able to get it close)
Remember, take your n/a tune (go to track, run it on motor and add timing until it doesn't gain any mph then back it off a degree or 2 for optimal n/a timing) and pull 1 degree for every 25 hp plus about 3 more, so example, if you are running say 26 degrees n/a, and want to put 200 hp of jet to the car, start with 11 degrees out. That should be close, your compression being as low as it is will let you run a couple more then a guy running alot of compression.
