3500 Fuel injectors, I need a source for higher flow

[Guest]

I don't know the rating of the 3500 injectors but am sure they will not be enough for 10 psi boost. If anyone knows of potential donor vehicles or sources for higher flowing injectors I would be grateful if you'd list them.

My initial guess would be late 3800SC and possibly the Ford 32valve V8 which also has Multec injectors but they probably don't flow much more than those found on the 3500 considering it's only a 4.6L.

[onefastV6]

I am not sure on the flow rate of the 3500 injectors. I have a set of injectors and fuel rail in the garage do they usually have a flow rate printed on the injectors?

[Syn]

I am not sure on the flow rate of the 3500 injectors. I have a set of injectors and fuel rail in the garage do they usually have a flow rate printed on the injectors?

nope none that i've seen,

how do you plan on running the larger fuel injectors? casue just swapping them in i dont see it happening with out some custom tuning

also u didn't specify the engine but most likely yours will use the bosh style injectors

[Joseph Upson]

The engine is from a 2005 Pontiac G6 with the latest design injectors which I believe are a little shorter than those found on the 3400. I'll be using the TGP 727ecm for fuel management. If there was enough room to install the earlier design fuel injectors it wouldn't be a problem however the upper intake manifold is pretty close to the top of the fuel rail so unless switching to the 3400 fuel rail provides additional clearance to make it possible to install earlier design injectors I'll be stuck for a bit.

[mcgavinz26]

If you have access to some tools and sweet skills, making yourself a little upper intake spacer would not be too hard. Just an idea.

[SappySE107]

Im hoping to have some plenum spacers made in the near future. However, you can modify your plenum to run teh 3400 fuel rail with the longer injectors. You could even modify that fuel rail for AN fittings and run a different fuel pressure regulator. Otherwise you have to grind some of the FPR down and a lot of the plenum TB arm. You would need to grind through and add material on the inside to fit it but its been done.

Im not aware of anything else for those shorter injectors.

[prodigy_16]

dont know if this helps, but alot of homemade turbo projects use injectors from the quad4 engine. not sure of the flow though, i think its 32pph

[Joseph Upson]

Thanks for the input, I believe the LSx and Supercharged 3800 fuel injectors may work fine, they are a little longer but the correct diameter, the LS injectors are around 28 Lb/hr and the 3800 SC 36 Lb/hr, I'm working on securing a set of them now.

The engine has ~7000 miles on it and it's to pretty to me for grinding on any part of it so I would much rather explore the possibility of modifying the 3400 fuel rail to clear the plenum including an extension for the pressure regulator or maybe modifying the 3500 fuel rail to accept a regulator which ever is easier. The left fuel rail is where the problem may occur since it is much closer to the upper plenum. I don't imagine a second gasket sandwhiched between the upper and lower plenum would be a problem if there is only a fine tolerance issue.

The QUAD 4 injectors are peak hold which is a no no for the TGP ecm.

[Manitcor]

yes use the L67 injectors 42.5lb. They have been used in previous 3x00 boosted projects and work fine.

Im not sure what car your putting this in but IMHO I would use a 98+ ODBII PCM with either DHP or HP Tuners setup.

[Joseph Upson]

It's going in a Fiero and I chose the TGP ECM because I do not have the tuning software for the ODB II PCM and want to keep it as simple as possible, I imagine the most practical OBD II platform to use would be that of the 3800 SC since it is the only thing I'm aware of that supports a 2 BAR MAP sensor that has actually been hacked a bit.

I understand the software for ODB II is rather expensive and I want full access to programming. I was fortunate to receive support from MARS and therefore have the ability to data log using Tunerpro RT along with a wideband O2 sensor, so unless I can get that kind of support with OBD II without coming out of the pocket much I'll have to stay the initial course.

[Manitcor]

It depends on what you classify as "rather expensive" the major tuners out there (HP tuners and DHP, im a DHP user myself) sit at about $400 for access to 15 or so cars from a list of about 70 cars.

DHP includes logging and data charting tools with it. Yes I would say a L67 PCM would be your best bet, mainly from a 98 or 99 GTP.

[Joseph Upson]

As a student with no job any unnecessary expense is to expensive. Except for any benefits that can be had with sequential fuel injection I really can't justify the $400 expense to use such a late design PCM on a vehicle with such out dated equipment, given the effectiveness of the TGP ecm. When I do however it will be in an effort to use the actual PCM that the engine was designed to run with. If I were running an automatic I would definately have to reconsider. As for now simple is better. I'll take your approach with modern technology when I get the time to work on my second Fiero and hopefully by then I'll have my hands on a 3900.

[Joseph Upson]

Anyone have any close up pictures of the 3400 fuel rail and the interference areas with the 3500 plenum, I just won an auction for the 3800 SC 36 lb/hr multec 3 injectors and imagine that the 3400 intake plenum is able to retrofit the earlier style wider diameter injectors since they are about the same length as the initial narrower version. So in the future if I some how manage to max out the 36 lb ers I'll be able to get a reasonably priced set of #42 injectors to fit with the 3400 rail on the 3500.

I thought it was a wild idea in the past to try and run high boost with high compression but given that GM recommends 87 octane for the 3500 with 9.8:1 compression and that I have read reviews on several production turbo cars in the area of 9-9.5:1 compression and double digit boost, I'm going to aim for 10-12 with intercooling and premium fuel. I'll tread very carefully tuning the base spark table without boost to find the potential detonation spots over the N/A range.

[prodigy_16]

aluminum heads are the answer, they do not absorb or retain as much heat as iron so more boost or compression (or both) is possible, but at the same time the extra compression is needed to make up for the power loss due to their nature to run cooler... weird huh?

[SappySE107]

I can take any pictures you want. I dont have a 3500 fuel rail or injectors but I have a 3400 and 3500 lower and a 3400 rail and a 3500 plenum. Tell me what combo you want and what area you want specifically and I will get you the pics.