Corvette Z06 Forum banner

1 - 20 of 46 Posts

·
Registered
Joined
·
314 Posts
Discussion Starter · #1 ·
Hello,

I am having some problems with my cam-only car and I think it's the injectors (Delphi-racetronix 32lbs)...the car was recently tuned in OPEN loop (Could not get enough fuel out of it) and is going through gas like crazy, has hot start issues (won't start after it was just shut-off), and poor idle & driveability at low rpms - which may be a result of the big cam. The car gets better MPG at speed compared to lugging around.

The gar runs great when your on the throttle.

Question: Are these injectors too big at low rpms (RWHP is 449) - does anyone have idle problems (surging) with these as compared to the SVO's or SLP 36lbs??? Is OPEN loop necessary at these levels?

Thanks for the help -

Bill
 

·
Moderator
Joined
·
21,378 Posts
I ordered the same injectors but wasn't able to install them correctly. They will flow around 36# at 58psi so they are not too large flow wise. They are however slightly shorter than stock and don't seem to fit in the intake manifold as well. I was afraid of a vacuum leak so I removed them. I put the stock ones in and never looked back. All surging and bucking is gone!

As far as the hot start issues, that is part of owning a cam. You will need a tune to take care of that issue.
 

·
Registered
Joined
·
314 Posts
Discussion Starter · #3 ·
Thanks for the help - the hot start seems to be from the injectors dumping too much fuel when the key is turned on (the fuel pump will not shut off).

I thought the stock injectors were maxed out at 430...do you know what you Duty cycle is?

Is your car in open or closed?

Thanks,

Bill
 

·
Moderator
Joined
·
21,378 Posts
THRLSKR said:
Thanks for the help - the hot start seems to be from the injectors dumping too much fuel when the key is turned on (the fuel pump will not shut off).

I thought the stock injectors were maxed out at 430...do you know what you Duty cycle is?

Is your car in open or closed?

Thanks,

Bill
I run in closed loop. I just bought Flash Scan and I'm in the process of learning how to tune my own car so I'm new to all this tuning stuff.

The stock injectors will run at 100% duty cycle when WOT and high RPM but anything less and they are fine. Since I don't spend too much time at high RPM they will suffice for now. I'm currently doing more research on injectors and I'm looking for the perfect ones.
 

·
Registered
Joined
·
2,127 Posts
The hard starting issue can be corrected with tuning. I have the same 32 LB injectors(36 lb at 56 psi) with the 90 fast and my idle is great, hot starting great but I have a bad bucking at around 1600-1900 range with light peddle. I think I can tune that out
I also have a terrible fluttering, misfiring, run like shit problem around 2200-2500 rpm range with slight increase of fuel. It starts perfectly at 2200 and goes away at 2500 perfectly. If I nail it thru that range I have no problem. It might be a TB issue also. I need to log some data and look at it. I show no misfire when scanning and plugs and wires are NOT the problem.
Lou at LG warned me that larger than 30 LB at 56 psi would cause problems. Jub Jub. I think you and I have about the same problem.
I would put the stock injectors back in but I think at 486rwhp they would be pegged.
Also if you are running out of fuel pressure, (ie filter plugged or pump low output) you will have high injector duty cycle because they are trying to make up for loss of fuel flow.
 

·
Moderator
Joined
·
21,378 Posts
Lou at LG warned me that larger than 30 LB at 56 psi would cause problems. Jub Jub. I think you and I have about the same problem.
My tuner basically said the same thing. He suggested that I run stock at anything less than 450 rwhp but I insisted on bigger injectors. Well, I can honestly say my car runs just about as smooth from 1500 - 2500 rpm as stock with the stock injectors. I'm happy now that the bucking and surging are gone. But on the down side, I'm probably starving for fuel at the upper end of the rpm range.
 

·
Registered
Joined
·
314 Posts
Discussion Starter · #7 ·
Thanks for the replies - here is the kicker - racetronix has a no refund policy and no voice customer support.

My tuner has done a great job with the bucking and driveability - only a little bit of surging below 1500. I have the NW T-body which I think is helping my driveability - my car idles around 925.

He is also recommending the SLP 36 lb injectors (Supposedly the factory injector in Grand Prix) and appear to be longer than the racetronix. Most GN guys run these with good success - I've heard some horror stories about the 30lb SVO's which have a great flow variance.
 

·
Moderator
Joined
·
21,378 Posts
THRLSKR said:
Thanks for the replies - here is the kicker - racetronix has a no refund policy and no voice customer support.

My tuner has done a great job with the bucking and driveability - only a little bit of surging below 1500. I have the NW T-body which I think is helping my driveability - my car idles around 925.

He is also recommending the SLP 36 lb injectors (Supposedly the factory injector in Grand Prix) and appear to be longer than the racetronix. Most GN guys run these with good success - I've heard some horror stories about the 30lb SVO's which have a great flow variance.
I also heard GP injectors were the way to go. Good news travels fast. Maybe I'll swing by the Pontiac dealer and see what they want for 8.

I've also read about problems with fitment on the SVO's as well. I don't if that's true. It seems to be a popular injector for cars with heads and cam.
 

·
Moderator
Joined
·
21,378 Posts
THRLSKR said:
Just checked GM parts direct - $59 / piece. SLP has a set of 8 for $324.
Thanks. Quite a bit more than what I payed for the Delphis. I guess I know why the Delphis were on sale now.
 

·
Registered
Joined
·
327 Posts
jub jub said:
I also heard GP injectors were the way to go. Good news travels fast. Maybe I'll swing by the Pontiac dealer and see what they want for 8.

I've also read about problems with fitment on the SVO's as well. I don't if that's true. It seems to be a popular injector for cars with heads and cam.
Hey Jub,

I installed to SVO's about a year ago. I have never had a problem since.
 

·
Registered
Joined
·
327 Posts
jub jub said:
Were they the perfect length?
Yes. Fitment was perfect. No fuel of vacuum leaks and no more 100% duty cycle at WOT. Just use a little motor oil on the o-rings and the slide right in place.
 

·
Moderator
Joined
·
21,378 Posts
GSMZ06 said:
Yes. Fitment was perfect. No fuel of vacuum leaks and no more 100% duty cycle at WOT.
Thanks. My tuner owes me a set of new injectors. I think I'll ask him for what I requested in the first place.
 

·
Registered
Joined
·
2,127 Posts
Jub Jub, get me a refund to. TEE HEE
Hindsight is a wonder full thing. But I asked and asked this question prior to screwing up and no one had a answer. BUT NOW WE KNOW.
just a $250 mistake
 

·
Registered
Joined
·
314 Posts
Discussion Starter · #16 ·
Question for you guys running the SVO's: Did you buy the flow matched versions or the non-flowed?

I am stuck SVO 30s or GP/GM 36ers?
 

·
Registered
Joined
·
327 Posts
I have the non flow matched version. I'm not convinced that the flow matched version will result in a noticeable amount of performance increase. I think it may be more of a marketing performance issue. :D
 

·
Premium Member
Joined
·
5,475 Posts
THRLSKR said:
Question for you guys running the SVO's: Did you buy the flow matched versions or the non-flowed?

I am stuck SVO 30s or GP/GM 36ers?

I am running 30#SVO's with my H/C package, and the one's
I bought are supposed to be flow matched. They fit as well as the stock injectors, and with the dyno and street tuning that FRC Tom and Greg did for me the car is very docile till you put the pedal down, then all hell breaks loose. One thing negative about all this is the gas mileage around town
went down by alot, which I expected, ya wanna play , ya gotta pay! LOL :D
 

·
Registered
Joined
·
314 Posts
Discussion Starter · #19 ·
Is your car tuned in open / closed loop? Open killes MPG from what I have heard - but still trying to figure out which is the preferred method for H/C cars.
 

·
Registered
Joined
·
30 Posts
THRLSKR said:
Thanks for the replies - here is the kicker - racetronix has a no refund policy and no voice customer support.

My tuner has done a great job with the bucking and driveability - only a little bit of surging below 1500. I have the NW T-body which I think is helping my driveability - my car idles around 925.

He is also recommending the SLP 36 lb injectors (Supposedly the factory injector in Grand Prix) and appear to be longer than the racetronix. Most GN guys run these with good success - I've heard some horror stories about the 30lb SVO's which have a great flow variance.
These injectors are in use in MANY LS1 / LS6 motors w/o problems. It all comes down to the tuner. The injectors are the same height and o-ring to o-ring they are the same and do not have problems sealing in LS1 / LS6 intake and fuel rail. Perhaps you should seek tuning advise on LS1TECH as there are many people there who have used them with great success. You may also consider contacting some of our dealers for tuning services and / or help.

We do not take returns on used injectors or any other fuel / electrical item. This is pretty much industry standard due to the nature of the product. The reasons for this are fairly obvious.
 
1 - 20 of 46 Posts
Top