OK guys i'm finally in the ballpark with the HP i should be running. first things first, i guess you don't want to gap your spark plugs at 32 like paxton says, as the spark was being blown at approx 5000 rpm and up, so i guess they should be gapped at around 28 to 30 to avoid this.
next i was told to install 60# injectors, which i did, only to find out that they are maxed out in the mid 5000 rpm range @ approx 700 rwhp.
the dyno was performed on an all wheel drive dyno, cant remember the name, but i do know that the readings are right on, unlike the overinflated readings with a dynojet.
so my question is: what is the next size up onjector i should go with. the dynop shop told me to try to find one that is at least around 75#'s.
thanx in advance for the help guys!
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You should be able to obtain (well) over 700rwhp with 10 x 60# injectors, especially if your taking them into high duty cycle (not to mention the very high fuel pressure that the paxton FMU is attempting to produce with its high ratio riser). What is your base fuel pressure and are you running a return fuel system conversion on your SRT?
Also, are you logging fuel pressure through the entire dyno run to verify that this is not a problem with the fuel pressure falling off on the top end? I am confident that given the information you have provided so far, that you are very likely to find the source of your problems here.
You may find that the Paxton out of the box setup of using a pair of external walbro 255s to pull thru your factory 255 in the tank with a fuel pressure riser may be pretty inconsistent making it difficult to tune. I have personally run into this issue with another SRT-10 with a paxton.
Can you share more details of your fuel system configuration? Depending on what exactly is causing your fuel system to max, I wouldn't want to see you drop the $$$$ for another set of injectors just to end up where you are now.
OK guys i'm finally in the ballpark with the HP i should be running. first things first, i guess you don't want to gap your spark plugs at 32 like paxton says, as the spark was being blown at approx 4500 rpm and up, so i guess they should be gapped at around 28 to 30 to avoid this.
next i was told to install 60# injectors, which i did, only to find out that they are maxed out in the mid 5000 rpm range @ approx 700 rwhp.
the dyno was performed on an all wheel drive dyno, cant remember the name, but i do know that the readings are right on, unlike the overinflated readings with a dynojet.
so my question is: what is the next size up onjector i should go with. the dynop shop told me to try to find one that is at least around 75#'s.
thanx in advance for the help guys!
in my paxton car i was running 44lb injectors, about 60 rwhp and the injectors were nowhere near maxed out
in my tt car I have 65lb injectors, on 91 oct making about 840-850 rwhp.
in my paxton car i was running 44lb injectors, about 60 rwhp and the injectors were nowhere near maxed out
in my tt car I have 65lb injectors, on 91 oct making about 840-850 rwhp.
thats more like it. im pretty sure after they look into it further they will discover a problem with the fuel pressure curve.
right now i am using the vec2 with semens 60# high impedance injectors. i picked up a walbro 255 pump for inside the tank.
now remember, no offense to anyone, but these are true dyno #'s, not over inflated like dynojet, etc. so it is making a true 700 rwhp right now, or if it was done on a dynojet i could say it is making 770 to 800 rwhp.
talking with cody at ART earlier today he told me that the vec2 cant handle an injector over 60#'s, so i may be fucked.
also i screwed up, i meant to say around 5500rpm and up the injectors are running out of fuel. i need to find out what the fuel psi is doing and i will report back.
thanx guys
Ok the little black injectors with the blue rings around them... those are decent quality and economical.
FYI, the stock pump is a Walbro 255. I am assuming you picked up a GCA761-2 SRT-4 Neon 255 kit and installed it (I say that because its the only aftermarket available walbro pump that is compatable with the SRT surge canister). The flow on that pump is the same as the stock Viper SRT pump according to the tech at Walbro I spoke with. So I have never tested that myself, but either way...
If you are only running that and not the secondary pumps supplied with the Paxton kit, than that is your problem for sure.
The absolute max that you will get out of a single Walbro 255 is ABOUT 650rwhp SAE on a Dynojet.
If you ARE running the secondary pumps still, I think you will most likely still run into fuel pressure consistency issues. You most likely will need get rid of the paxton secondaries if you are still running them, and put a pair of Walbros in your tank with an adjustable regulator and a set of fuel rails that you can plumb in a parallel setup. I am talking about going to a full return fuel system conversion with a 1:1 regulator in the engine bay. This might be a little overkill, but a balance fuel system is vital to longevity.
BTW while a Dynojet does read a little higher then some other dynos, its not THAT much higher man. Also, most dyno operators of Mustang, Dyno Dynamics, Dynapack, etc - all of them insert a correction of 1.15 which over corrects by 15% and easily surpasses Dynojet in numbers. Dynojet 248s inertia dynos are the industry standard for comparison in the USA simply because it is the ONLY dyno around that the operator cannot manipulate its numbers. So while it might read higher on its only setting then some other dynos on their baseline setting, unfortunately you never know what your getting on other dynos and if you want to compare to another Dynojet graph then you have to just get on a Dynojet. I dont make the rules, its just how it goes.
Last edited by phunk : January 3rd, 2007 at 01:33 PM.
I think you are way overestimating your power here Mike. Are you on a stock engine? What kind of boost? As far as the Vec handling the 65# injectors, my Vec is and so was Sagev before he switched over to the AEM.
I am also running less pump than you with just my Aeromotive Eliminator and not having problems like you are.
Well I do know that Cody @ ART sold me on one of his walbro 255 in the tank pumps and told me to get rid of the stock one. The Vec2 eliminates the Paxton's split second box which in turn eliminates the booster pumps. I do remeber Cody saying something about the fuel pump he sold me is good up to approx. 700rwhp, then its time to move to something different. I would imagine it must be time to go to what he's talking about. The paxton is making 8#'s of boost when it is in the upper 5k rpm range. I need to call the dyno shop and see what the fuel psi is at in the 5k range, that should tell me if its the pump or the injectors.
Seems like Cody at ART is telling me to buy a fuel system he has for approx. $1,500.00 which consists of modifying my fuel tank canister to accomodate 2 walbro 255's w/ fittings, a -8 braided supply line to an aeromotive fuel filter and fuel regulator w/ psi gauge, a return line, and 2 gen 3 modded fuel rails.
Hopefully this does the trick!
Seems like Cody at ART is telling me to buy a fuel system he has for approx. $1,500.00 which consists of modifying my fuel tank canister to accomodate 2 walbro 255's w/ fittings, a -8 braided supply line to an aeromotive fuel filter and fuel regulator w/ psi gauge, a return line, and 2 gen 3 modded fuel rails.
Hopefully this does the trick!
Is this a stock motor Mike?
If so and the only upgrade is the paxton and headers, etc. I think you are getting way over your head and spending way too much money on this install.
The stock paxton kit with everything it comes with has shown to make and support 700hp with the fuel system they supply and the split second. Do like Sagev did and use both the split second and the Vec. It sounds like whoever is helping you there locally doesn't know what they are doing. In all honestly you should just trailer that car up to Garth in Vegas (4hrs away) and have him square you away. They also have a fuel system that will support 2-3 walboros in the tank which is a full billet piece that replaces the whole canister that sits in the tank.
Seems like Cody at ART is telling me to buy a fuel system he has for approx. $1,500.00 which consists of modifying my fuel tank canister to accomodate 2 walbro 255's w/ fittings, a -8 braided supply line to an aeromotive fuel filter and fuel regulator w/ psi gauge, a return line, and 2 gen 3 modded fuel rails.
Hopefully this does the trick!
Ummmhhhh, that sounds like a load of shit Mike. ART does this kit day after day. I ran 60 pounders, and made 710 all day long. No issues at all. If you want to over do the fuel system, do what Cody suggests above. If you want to run the correct size injector and pump, do as he told you to on the phone. I happened to hear that conversation.
Ummmhhhh, that sounds like a load of shit Mike. ART does this kit day after day. I ran 60 pounders, and made 710 all day long. No issues at all. If you want to over do the fuel system, do what Cody suggests above. If you want to run the correct size injector and pump, do as he told you to on the phone. I happened to hear that conversation.
So are you saying to go with the $1,500.00 deal?
I do know as stated above that a single walbro can only handle approx 650rwhp, and from what a lot of guys have said that is about all you are going to get with a split second set-up. As Dave Weaver has said and a few others, the vec is a better set-up and adds an additional 50+ rwhp. The dyno shop here in scottsdale called Dynocomp, has an all wheel drive dyno which puts a load on the car as if actually on the street, as oppossed to a dynojet that dosent incorporate a load, therefore you will use more fuel, that may be why everyone has a different fish story as to what there fuel situation is.
I think I would take the original advice and do that. It seems to me like you are coming to a board to quantify the advice from someone who has done dozens of these. To me Mike, if you seek the advice from a shop, and then throw that up incorrectly to a forum, you are within hearing distance of being called a douche bag. If Weaver believes that you can run a drop in pump, and run 60 pounders and achieve the 700 RWHP without leaning out, he is correct. I had that same system, and it worked very well.
Seems like Cody at ART is telling me to buy a fuel system he has for approx. $1,500.00 which consists of modifying my fuel tank canister to accomodate 2 walbro 255's w/ fittings, a -8 braided supply line to an aeromotive fuel filter and fuel regulator w/ psi gauge, a return line, and 2 gen 3 modded fuel rails.
Hopefully this does the trick!
That is a good deal on a very good fuel system , they built mine and it works great.
I think I would take the original advice and do that. It seems to me like you are coming to a board to quantify the advice from someone who has done dozens of these. To me Mike, if you seek the advice from a shop, and then throw that up incorrectly to a forum, you are within hearing distance of being called a douche bag. If Weaver believes that you can run a drop in pump, and run 60 pounders and achieve the 700 RWHP without leaning out, he is correct. I had that same system, and it worked very well.
No I'm not being sarcastic, just trying to figure out what to do to fix the problem.
Unfortunately I spoke to Cody originally and asked what to do for a fuel system and he told me to run the walbro pump in the tank and thats it, but after taking the car out the other day, I now have a destroyed piston due to the car running lean, so needless to say I will be yanking the motor out and going with forged pistons now.
I will have to see what else I can do while the motor is out to get some extra power without breaking the bank. I guess I can do a lighter flywheel, and who knows what else. If anyone has some spare parts to make my engine quicker, now is the time to tell me, and if the price is right I will buy them.
No I'm not being sarcastic, just trying to figure out what to do to fix the problem.
Unfortunately I spoke to Cody originally and asked what to do for a fuel system and he told me to run the walbro pump in the tank and thats it, but after taking the car out the other day, I now have a destroyed piston due to the car running lean, so needless to say I will be yanking the motor out and going with forged pistons now.
I will have to see what else I can do while the motor is out to get some extra power without breaking the bank. I guess I can do a lighter flywheel, and who knows what else. If anyone has some spare parts to make my engine quicker, now is the time to tell me, and if the price is right I will buy them.
who is doing the tuning Mike? Dropping pistons isn't going to fix anything until you get the car to someone who knows fuel and tuning. Shipping a car is a hell of a lot cheaper in the long run.
thats more like it. im pretty sure after they look into it further they will discover a problem with the fuel pressure curve.
