ravencr

I've tried to get a concensus on what is the perfect size injector for a 1998 supercharged 4-runner, and I've seen differeing opinions. Can Gadget or Duffdog or anyone else shed some light on this for me. This is one of two last decisions I need to make before making the purchases. Thanks,

Chris

Texastwstr07

I would go with 305s or 330s. No more. I have 330s in mine and never had starting problems, but I live in Texas. I've heard others having starting problems with this size. I believe Gadget has settled on 305s and I installed a set of these in Doug Roys truck when we supercharged it a couple of weeks ago. They worked very smoothly. Just make sure you have some sort of controller to dial in the injectors and the timing or you will probably get a CE light for running rich.

ravencr

Thanks! I've heard that the 330's can be troublesome if purchased from Maxx, but I've also heard from Duffdog that the 370cc's are actually the better units to run. I've never heard a negative from the 305cc's, but I want to make sure I tap every ounce of power possible, and if that means using the 370cc RC's, then I'm all for it. Otherwise, I'll get the 305cc's. Thanks for the info!

Chris

Duffdog

ok well here it goes... basically all the facts i could compile from gadgets discussions, the maita shop foreman, and my own experience.

305cc injectors-- the perfect size for mild upgrades if you want to limit your horsepower to a reasonable amount. adding a supercharger, headers and exhaust warrants the install of 305's.

330cc-350cc-- the middle of the road injector, will support more HP with less fuel system tweaking with a supercharger, headers and a supra MAF.

370cc-- these are currently available from RC engineering and will support 465HP if your intending on going that crazy, otherwize, they are slightly oversized with a supercharger, headers and supra MAF on a different intake.

305cc injectors may NOT need an SAFC ( or other piggyback unit ) if you have a 98 or later revision ecu-- ( coincidently, toyota changed the cold start fuel injection to a leaner program after 98 ). Anything larger definitely will. using a SAFC with all of gadgets mods means you will have to have the SAFC all the way up all the time. This gives you no leeway for anything else at all. I personally have a 98 v-6 tacoma with everything and 370cc injectors and have not ever had a hard time starting my truck.

I believe that my choice of the RC eng 370cc injectors and the SAFC with all my mods will enable me to add more go-fast parts without changing my fuel system any more. ( AND THEYRE CHEAPER ) I question whether some funky mitsubishi injector is actually the correct physical shape for the toyota engine--i know for a fact that some supra injectors from 96-97 do not fit!!! in fact i have a box of 12 of them from 2 different supras that do not fit correctly! i know that they will go in the whole but they orifice of the injector must be past the air injection port or the air injection system will deflect the fuel stream away from the valve opening.

hope this helps everyone

Tim

ravencr

Thanks Tim,

I'm planning to run the following:

1) TRD Supercharger
2) Walbro 190 LPH fuel pump
3) 305-370cc injectors (based on yours and Gadget Recommendation)
4) Split Second FTC1-E or PP SMT-6 (based on Gadget and Dr. Z's recommendation)
5) Split Second ARM1

Down the road I'm going to do a full exhaust system for sure, but that's about it. Now, knowing that, what would you run 305's or 370cc's?? Do you recommend any other necessary needed options that will drastically improve all this? Also, I can get some 1995 SC300 red top injectors right now. Will they pop right in to my 1998 4-runner?

Chris

ravencr

After reading all this, I would think a 350cc injector would be perfect all around, but I don't think RC Engineering makes one, do they? Just wondering. This may the best of both worlds then. I wouldn't be maxxing it out, yet I would still have a tad bit of room to grow.

Still haven't determined if the '95 SC300 red top injectors will pop right into my 1998??????? Anyone know??

Chris

Gadget

When sizing your fuel injectors you want to install an injector that will deliver the amount of fuel needed at max demand and hitting the target of 80% duty cycle. You don't really want less then 80% if you can help it, and you certainly don't want more then 80%.

The injector is either open or closed. The duty cycle is how long it is open, not how far it is open like many people think.

Why is this important???

On an Otto cycle engine like we have at 6000 PRM the intake valve event is 15 MS long, normally. The best injection time is about 18 MS long. The injector should start injecting just prior to the valve event, but not inject after it because it will not go in the cylinder. Some how this all works out to be 80% duty cycle. This is important so that the fuel goes into the cylinder evenly with the air and makes a nice mix instead of a bunch all at once like with an injectors that is to large.

I would like to tell you that I am a very smart man and that I did all the math to figure out that my engine needed 305cc injectors to give me a perfect 80% duty cycle, but I arrived at that size more through trial and error then anything else. You can do the math and figure it all out that way, but you need to know what the true HP is and the BSHP concentration is for the mixture. I really did not know what the true HP was and that is why it was more of a trial and error method for me.

I did get lucky and nail down the proper size injectors for my engine and that is 305cc. This gives me the perfect 80% duty cycle and delivers the fuel in the proper quantity to give me the mixture I need.

Fuel pump sizing was another long drawn out process. I was able to figure most of that out with math since I knew what my injectors were really flowing and with some pump flow tests from a few other pump at different voltages, and comparing that to the end result in the truck to determine the friction loss of the fuel system. My math said 190 LPH pump and once it was installed it proved perfect again. It was simpler to start with the BAP so I could just turn the dial until it all worked right.....

There are limits to how large if an injector you can go with the stock engine control system and how much to can control with a piggyback device on the stock system. If you jump the HP up to high you may need a stand alone engine control system that will completely replace the stock system. Then you may have legal issues with the Feds and state emissions people.

There have been a lot of people that have had hot starting problems with the 330cc injector that MAW is selling, but when they are replaced with 305cc the problems go away. There are some theories as to why this happens, but no one really knows for sure. It may just be as simple as junk being sold by MAW, or something more complex like the engine start programming in the factory ECU. It is interesting that this larger injector hot start issue may not be occurring with the Supra MAF swap, but I would like to see that confirmed with someone else. If that is a fact then that is great news for me as I am planning an expensive major HP increase and larger injectors are going to be needed for me and I would like to be able to pull it off without a stand alone engine control system. Here is hoping....

So, what is the proper size injector for your needs?? That is a good question, and good luck figuring it all out. Just don't go venturing out trying to reinvent the wheel. If you stay with what has been proven to work time and time again you may save yourself a lot of headaches and money down the road.

Gadget

www.GadgetOnline.com

hell_on_ice

When do we get to hear about what you've got planned for this major HP increase? You know we all eagerly await your blessing on 4Runner performance mods. How much is my wallet going to hate you now?

ravencr

So, will 1995 SC300 Red Top fuel injectors work as 305cc injectors for my 1998?????????????????????????????????????????

Chris

Gadget

I don't know anything about red tops, blue tops, purple tops, green tops, and so on. I do know that the fuel injectors that I am using will work in your truck. Lots of people are using them and all have proven to have flawless operation.

If you want to venture outside the box and find another injectors that works well that will only benifit all those that follow. Before you install them please have them flow tested so we will know exactly what they are and after you install them will will know whether they will work for our application or not.

Go for it!!

Gadget

www.GadgetOnline.com

ravencr

On your site, Gadget, it says that they will work.
Toyota part number of 23209-46031 and said this is the same injector used in the following applications:

93-98 Toyota Supra NON-turbo
94-97 Lexus SC300
93-94 Lexus GS300 California Emissions
93-97 Lexus GS300 Federal emissions

What injectors are you running?

Chris

mhawker

Gadget has pics of which injectors he is using on his website.

It sounds like you are trying to find answers that, so far, no one has. You may have to be the pioneer in this area. In other words, you'll have to be the "Gadget" of red top injectors.

Can you work out a deal with the guy selling the red tops in case they don't fit your truck?

Keep in mind, all of these upgrades were NEVER designed specifically for our vehicles. That doesn't mean they WON'T work, but you are entering the phantom zone of upgrades. Gadget was nice enough to let us benefit from his many 100's of hours of work and experimentation, but even he can not cover every possible option. He only knows what worked for him.

Good luck with your search. I am hoping we can all learn from YOU!

Mike

ravencr

Me too! Do you still have those blue top injectors for sale? I assume those will fit, too, right?

Chris

Gadget

Well, if those injectors are in fact the same part number as the ones I am using then they should be the same as the ones I am using, but why are they different???

There is a picture of the injector I am using on my site. Take a look at the picture and see if it matches what you have and if the ND part number on the side of the injector matches. The last series of numbers will be the same as the Toyota part number if they are the same.

It kind of sounds to me that they are different, but in the end you are the one that has to make that tough decision. If they are different, they may or may not work, they may or may not have the same flow rate, they may or may not have the same spray pattern. You could roll the dice and see if you get a great deal on a suitable injector, or you may end up with a bunch of injectors that you can't use.

If you want you can send me 1 to 3 of them. I will test fit them in the engine I am building do see if they are compatable with the manifold and fuel rail or not and I can test the coil resistance for you. That much I can do. It that works you can then send them off to RC Engineering and have them cleaned and flow tested to see what they really flow at instead of what someone is claiming.

Let me know if I can be of more help to you.

Gadget

www.GadgetOnline.com

ravencr

You're the best! I'll be in touch to let you know!

Chris

ravencr

Hey Gadget,

Here's the part number off those used injectors I was telling you about. From what you just said about the part numbers, it doesn't look like they will work. What do you think?

Part number: 23250-46030 He says they are either red or brown top injectors from a 1995 SC300.

I'm very interested to hear your comments!

Chris

Gadget

That is not the same injector that I am using. However, I know that several people have used the injector you listed and they have been reported to work fine.

I would still send them off to RC Engineering to have them flow tested to be sure of the exact flow rate and make sure they are all cleaned and properly balanced with each other. You don't want a single cylinder going lean on you.

Gadget

www.GadgetOnline.com

ravencr

So, I'm going to base my decision on the fact they are going to work, right? So, I have Gadget's approval as long as they come back cleaned and flow tested, right?? How does $250 sound to you?

Thanks Gadget,

Chris

Gadget

I think you misunderstood. I have never even seen the injector you are talking about. I only told you that other people told me that they work fine.

Gadget

www.GadgetOnline.com

ravencr

Fair enough! You don't happen to know those other people off the top of your head, so I might be able to sicuss any querks they might of had with them?

Chris