I don't think I have ever read a post that proved Jon wrong. His Bosch IIIs in my 88 L98 are just what I wanted.
Injector size theory?
Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 2,295
Likes: 14
From: Grand Sport #82
Injector size theory?
I just ordered some new Injectors for my LT4. I figured the old ones have alot of miles and age, and and I have heard allot of good stories about the Bosch III injectors form FIC.
I have some mild mods right now (cam,headers,52 mm tb, flywheel, PCM4LESS + all the small usual ones), so I know I don't need a BIG injector right now.
Jon suggested the #32 as the common choice for my mods with room for further bigger mods. (heads, bigger cam)
His argument is that its all in the tune.
I am no expert on this so would like some more opinions/knowledge.
Does the injector size matter when you do a PCM re-tune?
Are there any downsides of having a big injector thats correctet for in tune?
Enlighten me
I have some mild mods right now (cam,headers,52 mm tb, flywheel, PCM4LESS + all the small usual ones), so I know I don't need a BIG injector right now.
Jon suggested the #32 as the common choice for my mods with room for further bigger mods. (heads, bigger cam)
His argument is that its all in the tune.
I am no expert on this so would like some more opinions/knowledge.
Does the injector size matter when you do a PCM re-tune?
Are there any downsides of having a big injector thats correctet for in tune?
Enlighten me
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St. Jude Donor '09-'10, '14
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From: Cumming Ga
I just ordered some new Injectors for my LT4. I figured the old ones have alot of miles and age, and and I have heard allot of good stories about the Bosch III injectors form FIC.
I have some mild mods right now (cam,headers,52 mm tb, flywheel, PCM4LESS + all the small usual ones), so I know I don't need a BIG injector right now.
Jon suggested the #32 as the common choice for my mods with room for further bigger mods. (heads, bigger cam)
His argument is that its all in the tune.
I am no expert on this so would like some more opinions/knowledge.
Does the injector size matter when you do a PCM re-tune?
Are there any downsides of having a big injector thats correctet for in tune?
Enlighten me
I have some mild mods right now (cam,headers,52 mm tb, flywheel, PCM4LESS + all the small usual ones), so I know I don't need a BIG injector right now.
Jon suggested the #32 as the common choice for my mods with room for further bigger mods. (heads, bigger cam)
His argument is that its all in the tune.
I am no expert on this so would like some more opinions/knowledge.
Does the injector size matter when you do a PCM re-tune?
Are there any downsides of having a big injector thats correctet for in tune?
Enlighten me
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There are two potential downside that I know of (and Jon knows of).
1) If you go too big with an injector the pressure and/or pulse might need to be adjusted so small as to compromise the ability of the injector to function at low rpms and/or idle.
2) Given the choice between a smaller injector with higher pressure and a larger one using smaller pressure, the smaller one may provide the best performance for a couple of reasons: Higher pressure might provide better atomization while the shortest cycles (at idle/low rpms) are also "strong".
There are min/max pressure ratings for injectors. If I'm not mistaken, I think that range is expanding with each new generation of injector -- so it can handle the widest possible range of conditions. In your case, Lars, it's the ability to perform well with only a few mods, while being able to perform well after you add more power to your car.
1) If you go too big with an injector the pressure and/or pulse might need to be adjusted so small as to compromise the ability of the injector to function at low rpms and/or idle.
2) Given the choice between a smaller injector with higher pressure and a larger one using smaller pressure, the smaller one may provide the best performance for a couple of reasons: Higher pressure might provide better atomization while the shortest cycles (at idle/low rpms) are also "strong".
There are min/max pressure ratings for injectors. If I'm not mistaken, I think that range is expanding with each new generation of injector -- so it can handle the widest possible range of conditions. In your case, Lars, it's the ability to perform well with only a few mods, while being able to perform well after you add more power to your car.
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Thread Starter
Melting Slicks
Joined: Jul 2004
Posts: 2,295
Likes: 14
From: Grand Sport #82
Lars, the lt4 uses a 26lb injector stock. Originally it was supposed to have 28 but prior to production they actually de tuned the engine, changed the cam and filled heads for less flow. They did this because the final numbers on the prior to production lt4 made more HP than the ls1 that was coming out in 97. So, by doing some head work, bigger cam and a good tune the engine will produce enough HP for a 32lb injector. Plus, give you some head room. The setting up of the PCM is imperative. I did not figure any altitude adjustment as Denmark is mostly at 100ft above sea level. The 32 Bosch along with Alvins tune will be all you need,
Perfect! Dont get me wrong Jon, I have big respect for your work and knowledge but its allways interesting to hear what the fellow Pistonheads has to say on technical matters.
Sounds like am am good, with plety head room for further modding, perfect.
I cant wait for my new injectors..I bet my 140K miles Multecs need a break now