My LGM built 402 still on stock fuel pump (see sig)

MeentSS02 · 05-26-2009, 02:49 PM

Well...there are many people out there on stock CORVETTE fuel pumps that put down some serious power. They are actually pretty good for a stock fuel pump from what I've seen, unlike the ones that came in the F-body.

To get to the bottom of this issue, you really need to log your fuel pressure, A/F ratio with a wideband, and knock retard while this is happening. Since, as best I recall, you don't have the equipment to do so, that makes diagnosing this problem a bit more difficult.

Por ejemplo - on my Camaro, I was consistently dropping about 6-8 psi of fuel pressure under WOT conditions. It bothered me to no end - I tried changing the fuel filter, replacing a kinked line in the back, and even went as far as putting new fuel rails in up front. No change whatsoever. I then decided to try running an adjustable fuel pressure regulator up front and removing the in-tank piece - that almost completely fixed the problem. I only drop about 2 psi under heavy throttle, all from simply changing the routing of the plumbing.

Long story short - you need some information that you flat out don't have right now. If you don't have the patience to get that information, take it to someone that does before you end up costing yourself more money than you need to. My problem ended up being something that I didn't expect at all.

Once you start modding a car to the extent that you have, all bets are off when it comes to reliability. That's the name of the game.

knappbunch · 05-26-2009, 03:04 PM

If you go with a walbro make sure it is a walbro! I had one from holley and within a year on my sts kit it was fried when i built the 402 it kept dyimng when it got hot we ordered an actual walbro pump and it has been running fine ever since. I do have a racetronics kit as well.

allngn_c5 · 05-26-2009, 03:09 PM

Quote:

Originally Posted by Spd-Kilz

Just to get this right, LGM suggested 30# injectors for a 500rwhp setup?

Did I read that correctly?

That's almost 110% duty cycle

They said I would be "marginally fine" with 30# svo's.

allngn_c5 · 05-26-2009, 03:15 PM

Thanks a lot for the info MEENTSS02 and Knappbunch

I have had a bunch of testing at a local dealership that my friend works at. After testing concluded it was found that I am running lean as early at 3800 rpms if I try to got WOT and hold it there beyond 3500 or so RPMS.

Ron at Vengeance has a solution to my fuel issues now and for future power. Won't be having anymore issues. Should be safe for a huge shot, or an F1 with some decent boost. Will need to change Injectors though if I go the F1 route with different heads (to drop compression) down the road.

blu byu EH · 05-26-2009, 07:26 PM

Post up about LGM people need to hear this and maybe they can change.

airforcemanss · 05-26-2009, 07:33 PM

^^hey doug. you wern't kidding when i talked to you on the phone lol. is your 402 built for FI in mind? im still trying to find out whether dish or flat pistons are best used for my future 418. i thought you were NA so what are you using doug?

allngn_c5 · 05-26-2009, 08:38 PM

Quote:

Originally Posted by airforcemanss

^^hey doug. you wern't kidding when i talked to you on the phone lol. is your 402 built for FI in mind? im still trying to find out whether dish or flat pistons are best used for my future 418. i thought you were NA so what are you using doug?

Yes and no. Internals yes, heads no. I'd need some un milled heads that really flow big numbers. For you 418, you can use either. Flat pistons if no valve reliefs are needed for PTV clearances and dish if you need additional clearances and lower SCR .

awd2rwd · 05-26-2009, 09:11 PM

Quote:

Originally Posted by allngn_c5

That was my first mistake. I should've as the customer been more insistent on a fuel pump upgrade, but as a TOP PROFESSIONAL shop LGM should've known that I would need a fuel pump upgrade. After not being taken serious about my concerns I gave up because it would be too hard to prove anyways. Just want everyone to know whats up though.

"HEY BRO" feel like your first mistake is giving your money to someone else to build your car that wouldnt do what you wanted. I think it is 100% hilarious the fuel pump wasnt upgraded but a stroker motor was installed.

, if a stock pump can handle 550. The piston selection is another story thats hilarious.

Honestly i would think you would learn that advertising for these shops can make you look pretty foolish but you already have another ad in your sig so obviously that wasnt a lesson learned....do you really think they care about you....or your money

Good luck with the continued build hopefully itll be smooth from here on

allngn_c5 · 05-26-2009, 09:19 PM

Well if I had the tools and the know how, I'd be doing it myself. Lets just hope the jump to Vengeance is a good move. Its certainly better then letting the car sit and rot. Thanks for you 2 cents. My post is not up to bash me, its to make people aware of a shop that decided to screw me over. In my opinion they felt like F it because hes not coming back anyways.

awd2rwd · 05-26-2009, 09:21 PM

Quote:

Originally Posted by allngn_c5

Well if I had the tools and the know how, I'd be doing it myself. Lets just hope the jump to Vengeance is a good move. Its certainly better then letting the car sit and rot. Thanks for you 2 cents. My post is not up to bash me, its to make people aware of a shop that decided to screw me over. In my opinion they felt like F it because hes not coming back anyways.

You can only learn by experience, getting out and doing it! Just constructive criticism not bashing

allngn_c5 · 05-26-2009, 09:28 PM

Quote:

Originally Posted by awd2rwd

You can only learn by experience, getting out and doing it! Just constructive criticism not bashing

I hear ya bro, but when you mess up on a corvette its very expensive. Its not like learning to work on a 100.00 beater. I do a lot if not most of the maintenance stuff on my DDr's but I do it at my buddy's garage and if I get hung up he bails me out. I was happy as hell when I did a complete plug, wire, and coil pack replacement on my 99 gran prix. I also did the plugs, wires and power steering pump and pully on my 93 gran prix. That's about as involved as I want to get too. I think that maybe when the 93 dies (236,200 and counting miles) I might drop it off at my boys house and begin a tear down just to learn. Just a little nervous about messing up my corvette. Thanks for the constructive criticism.

Before of sponsors that take your money, but don't take you input.

awd2rwd · 05-26-2009, 09:44 PM

Quote:

Originally Posted by allngn_c5

I hear ya bro, but when you mess up on a corvette its very expensive.

Trust me I know im in the process of installing my 2nd stroker motor on my c5 and im only 23

allngn_c5 · 05-26-2009, 10:21 PM

Best of luck. Maybe if I were to find a nice rolling chassis I'd be willing to build a motor. That would be cool.

Haans249 · 05-27-2009, 11:12 PM

I have the same "jar of marbles" sound in my vehicle at WOT. Your car is a M6 correct? I bet its the transmission thats making the sound. Not saying your transmission is breaking or bad, but its transferring vibration into your shifter causing the "jar of marble" sound. Your choice in the Racetronix's kit is a good one. Detonation doesn't quite sound like that. Its kinda hard to explain what it sounds like, but you will DEFINITELY feel a HUGE loss of power if it were pinging, like it were bogging down, and if you don't, then you're fine. Best thing to do is make a WOT run, and shut'er down, pull a few plugs and read them. You will clearly see if its running at the right AFR or not. Or get a wideband

allngn_c5 · 05-27-2009, 11:53 PM

thanks for the suggestion

Spectre86 · 05-28-2009, 02:15 AM

Quote:

Originally Posted by Haans249

I have the same "jar of marbles" sound in my vehicle at WOT. Your car is a M6 correct? I bet its the transmission thats making the sound. Not saying your transmission is breaking or bad, but its transferring vibration into your shifter causing the "jar of marble" sound. Your choice in the Racetronix's kit is a good one. Detonation doesn't quite sound like that. Its kinda hard to explain what it sounds like, but you will DEFINITELY feel a HUGE loss of power if it were pinging, like it were bogging down, and if you don't, then you're fine. Best thing to do is make a WOT run, and shut'er down, pull a few plugs and read them. You will clearly see if its running at the right AFR or not. Or get a wideband

not true. that would be severe detonation and would have been felt while at LG (to that extent anyway). bogging down would feel like its too rich. severe detonation would feel like its hitting the rev limiter.

an engine can detonate enough to do damage, but could be a light case. either way detonation over time can lead to problems.

I rode in my buddies STI on 22psi. It had a really nasty hicup around 5000rpms, it would pull like it was going to take off, but as soon as 5000rpms came, it felt like it hit a wall, then would pick back up. a retune fixed it, but could have done major damage if it wasnt fixed.

my point is, doug can still have detonation that doesnt apear to be that severe, (huge loss of power or feel like a rev limiter) but still cause damage.

I wouldnt be doing wot pulls if there is a problem like that. granted its forged and im sure it can take abuse, but detonation is detonation. im sure he spent a pretty penny on the motor. im not saying it will blow on the 1st time or even at all, just one of those things where its best to wait and either get it at a shop or a wideband with data logging. looking at a plug after a few pulls is going to be hard for the naked eye to tell the difference between safe tune and borderline lean.

Doug, do you have a wideband installed? or are able to datalog?

Innovate LM-1 is a nice one. I ran the AEM UEGO wideband on my last car. very simple to install and read. .

Haans249 · 05-29-2009, 09:14 AM

FYI Specter it is true, the corvette will pick up the pinging and pull timing. If it were detonating, he would have seen it in his TechII if it were anything worth worrying about. In these larger motors, even if it were pinging slightly (around 2-4 degrees KR) you will definitely feel it bogg down (rev-limiter/loss of power or what ever else you want to call it). If the sound is as audible as he was saying, and suspected pinging, it would be severe and kill power lol. Also, even a stock vehicle pings, even on its super soft stock tune/lower compression. Its just the nature of the beast.

Doug, If you aren't detecting any ping, and you thinks it is, then you need to check the knock sensors to make sure they're not melted/damaged. If they're good, then its something else especially if you're is saying its a very audible "jar of marbles" sound. That is something the knock sensors will definitely pick up.
As far as the plugs go, that is the BEST way to check and see if your motor is running at its fullest efficiency (other than playing around on a dyno). Not all motors like the same AFR to make maximum torque, and you can check to see how its doing by reading the plugs to see how efficiently its burning. You can also see just about every condition from the plugs including any undetectable detenation, and reading the plugs is the ONLY way to detect it. Before you do anything else, I highly suggest pulling a few plugs and checking them out to make sure everything is in order (if you still have your vehicle with you).

Hope you get it figured out!

allngn_c5 · 05-29-2009, 10:57 AM

The problem stems from a stock ls1 fuel pump that was marginally at best holding fuel pressure on the dyno. On the street it was completely different. Leads my to believe the problems I am having come from not enough attention being paid to the tuning of a NEWLY BUILT forged motor. Anyways not to kick a dead horse but the pump held pressure on the dyno and I speculate that LGM felt it was good to go. Fuel pressure drops significantly under load. I don't have the numbers in front of me as I was doing the driving and a tech buddy was logging. Stay tuned.

One more thing, the pump had 49K+ on it and was probably beginning to fatigue at the previous power level. Now with the greater demand for fuel the pump is just plain worn out. IMHO. Car drives fine under partial throttle, little surging, not much, but go wot and it sounds like a popcorn maker.

Nasty N8 · 05-29-2009, 11:27 AM

You can also desensitize or shut off the knock sensors in the tune. Could be why he would not see any KR but get a ping.

Nate

allngn_c5 · 05-29-2009, 01:40 PM

Quote:

Originally Posted by Nasty N8

You can also desensitize or shut off the knock sensors in the tune. Could be why he would not see any KR but get a ping.

Nate

Thanks for the input everyone. I'll have Mike at Vengeance (he's going to go over every bit of the tune on the street to dial her in, then WOT on the dyno) look at it. Maybe the knock sensors are tuned out ?? Don't know why they would be, I know I was charged for ls2 knock sensors.