7th Injector Kit

[Marc87GN]

I was just curious as to why I don't see more people using it. I would imagine that even with 7 small(36lb) injectors, that you could go alot further. Is it more difficult to tune? I was thinking about it, but I don't see many people using it and was wondering why.

 

[BoostKillsStres]

Think about it this way, you have a chip designed to give a certain amount of fuel for a certain boost level. Anything fuel or boost related outside that range will give you a rich or lean "er" condition. So, at 17 psi or so when you activate the 7th you go much richer. Now under race conditions this might not be a bad thing with race gas and extra boost would allow you to use this fuel but you can hopefully see it would take a bit more tuning to see what the car performs best at so it makes things more complicated.

Trying to run it on the street could make things pretty soggy on the topend and if you remove fuel pressure to make the topend good you may be too lean on the lowend spool or transitional knock areas.

Now if you have a chip that can automatically compensate and adjust the fuel when the 7th comes on or if you set the 7th to run full time and adjust the inj constant in the chip to correct this then things can work pretty well and you will have additional fueling available and you get some charged air cooling out of it too.

When I was running my 7th full time, I was seeing 15 to 20 degree cooler air in the upper plenum and that was under normal driving conditions when the 7th is running very small cruise pulse widths so I assume it would be as good or even better under WOT conditions but never got around to testing that. I've moved to 60's now so haven't yet turned the 7th back on but plan to as my chip corrects realtime for any fuel or air flow condition, but again I run the 7th full time so there's no sudden blast of fuel to deal with.

HTH

 

[Ormand]

The seventh injector was useful when injectors were smaller, and when chip design was more primitive. Now, it is easier to use a chip designed for big injectors, and to replace all six. You won't have the distribution problems you can have with the seventh injector, and it's much simpler to set up and tune. And seven 36 lb injectors will cost more than six 50 lb injectors, with less fuel flow capability. On the other hand, the seventh injector is "street legal", for emissions laws, and that may not be true of going bigger on all six.

 

[Marc87GN]

Originally posted by Ormand
The seventh injector was useful when injectors were smaller, and when chip design was more primitive. Now, it is easier to use a chip designed for big injectors, and to replace all six. You won't have the distribution problems you can have with the seventh injector, and it's much simpler to set up and tune. And seven 36 lb injectors will cost more than six 50 lb injectors, with less fuel flow capability. On the other hand, the seventh injector is "street legal", for emissions laws, and that may not be true of going bigger on all six.

I don't think the fuel distribution is an issue if you are running an RJC powerplate. I would imagine that the fuel spray would be delivered in the same manner as the incoming air and all of te cylinders would have good balance.

 

[turbo2nr]

i run a 7th shooter. It has jets to change instead of an injector. Cheep, and easy to tune. Fast to change at the track. If you need a little more fuel, just go up one jet. Sure you could mess around with chips, and getting your computer changed to peak&hold, bigger inj, but then you may be too fat at idle and part throttle. BIG injectors do have a minimun they can flow. I fine tune with my 7th shooter. Love it!

 

[gincole]

Hi, we're new '87 GN Owners, have all sorts of paper work on this thing - Applied Technologies stuff and I guess they're gone. My husband is looking for a manual or something on the 7th injector. There is a small black box sitting there with a black wire coming out of it. The wire is not attached to anything and we sort of think it should be Can you help?

 

[Nasty Wendy]

Back in 'Ye Olden Days' the largest injector we could run was the 009's which are 42lbers. To go larger you would have to have the ecm modified so that low Ω injectors could be used. ATR offered a 7th injector kit that allowed us to get more fuel into the motor without modifying the ecms by employing a 7th injector. It was a bandaid back then but it did give you the option of not sending off your ecm to get modified or purchasing a modified ecm. With the injectors available today that can be driven by the stock ecm it isn't practical to employ a 7th injector.

 

[RatFink]

Hi, we're new '87 GN Owners, have all sorts of paper work on this thing - Applied Technologies stuff and I guess they're gone. My husband is looking for a manual or something on the 7th injector. There is a small black box sitting there with a black wire coming out of it. The wire is not attached to anything and we sort of think it should be Can you help?

Wendy is correct. Please trash that thing and contact turbotweak.com for better fueling systems and chip availability. Good luck with your new GN!