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-   -   Throttle Body and Injectors (http://www.grandamgt.com/forum/showthread.php?t=91171)

Danspeed1 10-28-2017 12:51 PM

Throttle Body and Injectors
 
Working on an LX9 3500 swap on an 02 GA. I am having trouble finding information on throttle body sizing and what will work with our 3x00 engines. I am looking for a set of junk yard injectors to pull from a car as well as a throttle body. Thinking somewhere in the 60-70mm range for the throttle body and 36#injectors. What can I get those parts out of ?

Dan

AleroB888 10-29-2017 03:45 AM

http://www.grandamgt.com/forum/showt...nvoy+injectors

Some modification of the 36's, or the fuel rail bracket, or changing the fuel rails may be needed. I cut new mounting slots in the injectors....

Danspeed1 10-29-2017 11:10 AM

Wow, That was exactly what I was looking for. Thank you so much! Now if anyone has the same info for the throttle body ill be set

Thanks,

Dan

AaronGTR 10-29-2017 11:31 AM

Just fyi, if you are leaving the 3500 mostly stock, you don't need larger injectors. That will do absolutely nothing for you (except give more tuning headaches). The stock 3400 injectors have plenty of room for a 100cc increase in displacement, and even a cam and headers. A bigger TB won't really do a lot for you either, without other mods.

Danspeed1 10-30-2017 12:59 AM

Quote:

Originally Posted by AaronGTR (Post 1266723)
Just fyi, if you are leaving the 3500 mostly stock, you don't need larger injectors. That will do absolutely nothing for you (except give more tuning headaches). The stock 3400 injectors have plenty of room for a 100cc increase in displacement, and even a cam and headers. A bigger TB won't really do a lot for you either, without other mods.

My plan is to take advantage of a couple of other air flow mods and then tune the vehicle. I will be creating two tune files... one for 93 octane and one for E85.

Dan

AaronGTR 10-30-2017 11:51 AM

Most people still don't need bigger injectors unless you are adding boost. You need heads/cam/headers along with full intake, exhaust, TB, and ported intake manifolds to even approach the limit of the stock injectors. You need to do the mods first, then log some data and see where the injectors duty cycle lands. Most people with those mods find it sufficient to upgrade to 28# trailblazer injectors, and those don't require any mods to the injectors or fuel rail. They are plug and play, other than the need to scale the injector size in the tune.

Danspeed1 10-30-2017 12:08 PM

Quote:

Originally Posted by AaronGTR (Post 1266725)
Most people still don't need bigger injectors unless you are adding boost. You need heads/cam/headers along with full intake, exhaust, TB, and ported intake manifolds to even approach the limit of the stock injectors. You need to do the mods first, then log some data and see where the injectors duty cycle lands. Most people with those mods find it sufficient to upgrade to 28# trailblazer injectors, and those don't require any mods to the injectors or fuel rail. They are plug and play, other than the need to scale the injector size in the tune.

Ok, that sounds like good advice.. so Ill take it. I can get a set of trailblazer injectors for about $20 total so Ill make the swap. You are correct about data logging first. I'm just trying to leave myself some room. I can't imagine GM left too much room. E85 takes away about 30% of my duty cycle. Why have a duty cycle at 90% when you can have room at 50-60 at WOT on a larger injector? Scaling is not a problem, I will be using HPTuners. E85 is about a $1.94 right now in my local area. 93 is over $3.00 a gallon. On a 3500 ill pickup maybe 4-6 horsepower moving from 93 to E85 and turning the timing up, but Ill be saving money on the fuel, and practicing my tuning skills on something cheap before I start working on my other project.... the Turbo LQ4 I am building and the 454 Chevelle I have converted to a flex fuel standalone 0411 ECU.


Thanks,

Dan

Danspeed1 10-30-2017 12:14 PM

https://cimg5.ibsrv.net/gimg/ls1tech...62d6df67f9.jpg

AaronGTR 11-01-2017 11:22 AM

Well, most people's first instinct is just to go to way bigger injectors than they need to have plenty of room available, but that can cause tuning and idle issues. The stock injectors actually have a decent amount of capacity in them over stock power levels.

If you are going to run E85, well yeah... then you are going to need more injector. You'll also need a bunch of other mods though too. The stock fuel system isn't designed to accommodate that much alcohol. Plus there is the fact that in northern states, E85 isn't actually 85% alcohol year round. Alcohol is difficult to get to burn in cold temps, so in winter they switch to something closer to E65, and in summer it's E85. That means if you have a static tune, your fueling will be off when it switches. If you tune for E85, you'll be running rich in winter.

Factory vehicles use a fuel sensor to detect the alcohol content (about $400 from GM for the sensor). I read a good article a while back in a magazine where the converted an R33 Skyline in Las Vages to run E85 so they could up the boost and increase timing. They had to upgrade the fuel pump and replace most of the fuel lines and fittings to handle the extra flow and resist the alcohol, get special injectors, the GM fuel sensor, and a standalone engine management system that was capable of adjusting the fuel and timing mapping based on the fuel content (like the factory ECU on a flex fuel car). Not cheap or easy. You can do it without some of that stuff... but it won't be as safe or last as long. Not worth it for 4-6 HP in my opinion.


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