Buddy has a 94 corvette and is planning on doing a vortech or procharger style supercharger. He and I are totally clueless on the fuel system upgrades everyone does. He wants to upgrade it before the sc is installed. His motor is stock except LT headers no cats,no resonator into flowmasters.

He wants to add a sc but wants to do it with proper upgrades to hit his goal which is like,400-420rwhp,not much but good for him!

We want to know what type of pump,regulators,injectors to use on a stock motor.????? Feedback need please

 

I want to know the same,sorta,kindof

I was looking at Racetroinix for the fuel pump and Aeromotive makes a LT1 corvette regulator thats made for boost referencing. I hope those items work together cause thats what I want to use.

I've been trying to find more info on FMU's and which one is proper myself,maybe some of the wise will come chime in and help.

 

for that kinda power I would grab a set of 42lb injectors, and an intank bosch fuel pump. should be good for around 500rwhp with a tune.. I would also grab a good adjustable fuel pressure regulator.. this should do it.. tell him to lay about 500 bucks aside for a good dyno tune also.. where are you located?

Chris

 

Thanks,im in central california near Los Angeles. Does that Bosch pump need to be anything specific like model # or is the stock brand Bosch Corvette pump ok for his model year?

about that regulator,does it truely have to be boost referenced/adjustable even if i have a custom tune and larger injectors like those 42's?

Thanks chris fior a reply

 

You can use the Bosch pump as mentioned above or go to the Walbro series pumps. They can definitely be made to handle what you are trying to do.

If you are "ditching" the FMU, then the 42 lb/hr injectors will work just fine, and even give you a bit of growing room. The factory regulator will reference to the boost, just not like an FMU to get the very high pressures. But if you have someone who is going to do the tune on the dyno w/ wbO2, then the factory regulator should be just fine (the tune will handle the lower flow/psi by changing the time that the injectors are open).

If you were modifying further, more HP, then I would feed each rail seperately, with an Aeromotive boost referenced regulator. I think for your application, you will be just fine with the factory regulator and a healthy pump with a good tune.

Aaron

 

Thank you for both replies,very helpful and will take advice

 

personally, I would not use the FMU... dyno tuning in larger injectors is a much better way to tune and get the best power and driveability and less chance of catastrophic failure to the engine form a problem in the FMU.

I prefer using an adjustable fuel pressure regulator and using a little bit higher rail pressure then factory to tune with.. shorter pulses and high pressure equals better atomization from experience and can help sometimes with larger High impedence injectors which can sometimes be a little lazy.

the stock regulator will work, but for around 140 bucks a nice unit could be had.. I agree with Aaron, if you plan on going bigger down the road I would hold off until you do so.

I personally am anti Walbro as the customer support for them has gone down hill considerably and I have some bad experiences with bad pumps.. the bosch units are a little more expensive, but are a superior product and will give you better results overall.. a single large bosch pump will outflow the walbro GSS340m pump, I do not know the Bosch pump # off the top of my head, perhaps one of the other gents in here can chime in with it.

Chris

 

Chris, is this Bosch pump a stock corvette pump/replacement part or is a special part # that is for higher volume/psi applications?

Thanks Arron and Chris

 

Captian,

I agree with the above posts go with the 42 injectors, get a tune...

If you go to www.blowerworks.net greg has quite a few bits of information on his site. He normally stocks the stuff as well and is a great resource as others in this forum...

You can also contact him at : greg@blowerworks.net

I'm using Walbro 392 and a 340... see my signature below

Hope this helps

mo

 

Hi Captain Commando,
Greg here from BlowerWorks and I'd like to share my experiences with you regarding pumps, fuel rail regulators and FMU's.

I sell the Racetronix wiring harnesses, Walbro fuel pumps, and Siemens injectors. I also stock and sell several Bosch fuel pumps including the GFP-214 which is their highest flow/pressure fuel pump.

A while back I did a comprehensive posting on fuel pumps with Excel graphs on flow vs. head vs. voltage (the Excel graphs were put together by MO - tks MO). The Walbro GSS-340M has a free flow of 80 gph. The Bosch GFP-214 has a free flow of 60 gph.

The Walbro GSS-340M is a direct replacement pump for your LT1. I've installed many GFP-214's into LT1's but it is not a direct replacement and takes some work, including machining the pump inlet to accept the 'sock'. I recommend the 340 today because it is easy to install, outflows the Bosch and costs far less.

The Walbro GSS-340M will support 750HP @ 60 psig @ 13.5vdc. In conjunction with a centrifugal blower making a nominal 10 pounds of boost that equates to approximately 600 RWHP.

My recommended set-up for a 600 to 1000 RWHP C4 vehicle is a Walbro in-tank GSS-340 feeding a Walbro GSL-392 in-line. With the two pumps in series you avoid any flow loss or pressure drop @ 60 psig (due to the internal relief valve on the 340) and by sharing the load the two pumps coast at 1/2 the amperage of a single pump trying to do same. To support the 1000 RWHP you require the Racetronix harness in conjunction with a MSD or KenneBell pump voltage booster.

The two pumps in series also allows for the reliable use of a FMU. Most problems with FMU's result from inadequate pump head. An FMU is just like your fuel rail regulator but with a different 'ratio'. Your fuel rail regulator is indexed to manifold pressure and is designed to keep the pressure differential across the injectors at a constant by increasing the fuel pressure 1 psi for every 1 psi increase in manifold pressure. The FMU's from say Vortech are available with 3:1, 4:1, 6:1, etc., all the way up to 12:1.

About now I've got a few people upset with me for promoting the FMU. The reason I am is because at present there is no good alternative that I know of for the many Mass Air Flow 1985-89 L98's Corvettes (other than switching to an aftermarket ECM like 'FAST' etc.).

Without getting into lengthy details the 1985-89 MAF L98's can only read 0-255gms/sec making it difficult to add fuel as needed on high HP applications. I am looking at alternative MAF sensors for these vehicles.

Captain, back to your LT1. A direct replacement GSS-340M with a set of high impedance Siemen's 60's in conjunction with a new chip or flash for same and you are done and certainly set-up for your desired RWHP. I see no reason to replace your stock fuel rail regulator. Many aftermarket regulators do not match up to the GM.
Best regards, Greg

 

I would have to agree with Greg, the 340 is the easier of the two and I use a walbro in our 95 blown vette, BUT... and this is my reason for not liking the walbro, I have had so many issues dealing with Racetronix/walbro that the initial less expensive cost on two of the 340m pumps I purchased was quickly outweighed by having to purchase more pumps because they changed their warranty and I happened to receive a pump that did not work from day one. It had a faulty pressure bypass that bypassed fuel when set against ANY head pressure while my other intank walbro was taking the load. this pump on my setup and 14 psi boost was out of steam at 514rwhp.. my AFR was steadily leaning out no matter what I did with the VE table... this showed me the limitations of the walbro (at least on my setup..) I was using -10an feed line and a -8 return line with split individually fed fuel rails and a 2-port aeromotive regulator with base fuel pressure set to 43psi. I removed my walbro setup and went to a single externally mount aeromotive A1000 pump with a billet fuel pump controller and the engine starved for fuel NO MORE and my fueling headaches disappeared.

I put alot of Faith in Greg and his testing, but I have problems trusting in Walbro's product right now and the completely unprofessional way they try and point blame on the consumer immediately and their warranty or even their concern to investigate their product.. they make it very difficult for the comapnies who sell their product like Greg Caroll at blower works and Racetronix who themselves put out first rate products that they build but the components used in my opinion are lack luster at best with no one ready to stand behind them. If I wasn't going through the ordeal I am going through now and have been for the last 5 months where it took several public announcements on various forums to get a follow up phone call. and finally as of the last week or two get an address to send my pump back with a "we'll look at it but I can already tell you it was probably operator error" that doesn't sit well with me.. twin pumps, one works.. the other does not, followed all their testing procedures to try and free a sticking pressure check ball they came to the conclusion was the problem, then the next guys says they can't be freed that way... I lost my faith, which guy was right which guy was pawning me off?

Now to their credit.. I am running two cars with a 340 M that are working fine (pumps bought from Greg.. and a huge thanks for rush delivery!!!! ).. so when they work they work nicely, when they don't you're better off ponying up for another pump because getting resolution from walbro is like trying to under go a root canal without an aenesthetic.. painful silly, and in the end un worth the effort.

this is in no way against Greg who has been nothing but great and I trust implicitly, just the pumps themselves I got burned on.

I am going to send this faulty pump in and I am completey doing so under the assumption that (A) I may not have word on it for months, (B) it will be returned or a letter returned stating it was all my fault and will not be covered (although both pumps installed same time same way carefully.. one filter sock shows signs of pumping fuel while the other is completely clean still... faulty pressure valve would still cycle fuel showing signs of filter soiling.. and yes the tank was 100% empty when this was installed and completely clean and dry before clean fresh fuel was filled) I was hoping to use these as replacements for the new ZR1's twin intank pumps for the Twin Turbo project on it. oh well...

OK off my soap box.

Chris

 

Thanks for the feedback and in plenty of detail I learned quite a bit from everyone so far. Thanks I'll keep everyone posted as Im getting interested in Boost the more I go with my buddy.