Any problems putting 36# injectors in my stock 89?

CaifanSC

SCCoA Member
I posted about this a while ago but didnt get a reply. I have a set of 36# injectors and im wondering if i will have any problems if I use them on my 89. No tunning or reprogramming? Im using a 73mm C&L but i know those are calibrated for 'stock' injectors which are 30# & 36# so i should be ok using that. Thanx for the help.
 
CaifanSC said:
I posted about this a while ago but didnt get a reply. I have a set of 36# injectors and im wondering if i will have any problems if I use them on my 89. No tunning or reprogramming? Im using a 73mm C&L but i know those are calibrated for 'stock' injectors which are 30# & 36# so i should be ok using that. Thanx for the help.

No problem, so long as you get the correct sample tube for the C&L meter.

David
 
Ah, great...tahts good to know. Now if you can school me in something Dave. Would this be an 'upgrade' or would i see no difference? Im thinking it might just be the same since the EEC is programmed to 30# injectors.
 
CaifanSC said:
Ah, great...tahts good to know. Now if you can school me in something Dave. Would this be an 'upgrade' or would i see no difference? Im thinking it might just be the same since the EEC is programmed to 30# injectors.

You are correct...it won't make any differince unless you needed larger injectors. When you reach the point of needing them you will also have to install a larger fuel pump (190 lph).

I would keep the stock ones until you outgrow them.

David
 
If they are stock 94 SC injectors do not use them. They are horrible injectors and will likely run poorly on an older processor. There is no performance gain from injectors. It's only a matter of matching your HP levels with your injector and fuel pump capacity.
 
XR7Dave....does that pertain to using (on an early pocessor) stock 36# injectors in general? Or just 94 injectors on an early processor? Since i have a 94, im curious...why do you say the suck?
 
CaifanSC said:
XR7Dave....does that pertain to using (on an early pocessor) stock 36# injectors in general? Or just 94 injectors on an early processor? Since i have a 94, im curious...why do you say the suck?

Injectors have are rated in pounds/hr at 100% duty cycle - meaning open all the time.

In reality they don't run like that very often, and when the car is idling they actually spend more time turning off and turning on than actually open. During the time they are turning off and on there is a period of flow which is not equal to their open flow. Just like turning off and on a water tap. How quickly the injector can transition from closed to open and closed again will have a direct effect on how much fuel is actually released. This has to be compensated for in the EEC programing, and the truth is that injectors vary a lot in how they respond during this short on/off cycle at idle and low load.

In simple terms the 94 injector "dribbles" like a 50lb injector at idle, and then performs like a 34lb injector at WOT. This is not a big problem for a 94 because the EEC is programmed to compensate. However, the 89 processor is calibrated for a much better quality 30lb injector which acts like a 33lb injector at idle and a 30lb injector at WOT. So, if you put 94 injectors in your 89 without reprogramming the EEC and instead just use a calibrated MAF, it will get way too much fuel at idle and not enough under load. So you get crappy idle and it runs lean under load. Bad news no matter how you cut it. The EEC can compensate for some of that automatically with adaptive strategy but it will put the EEC at it's limit and may cause it to learn some false values as well.

Quality aftermarket injectors will more closely match the load ratio of the stock 30lb injectors (the 33 low slope and 30 high slope ratio).

:)
 
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