Vortec heads
- Thread starter flintdawg
- Start date
jwaller
Evil Genius/SyTy Guru
yes.....vortec's require quite a bit of modifying to get them to bolt up...their bolt pattern is totally different and the head must be redrilled and tapped for early model 6 bolt pattern....then the lower manifold must be port matched and welded to fit...It is worth it but it's a lot of work most ppl choose to let others do it for them
Jwaller, what kind of duty cycle are you seeing with those 50lb injectors? With ported vortec heads and a ~900 cfm turbo are you getting enough fuel? I don't know if you are running a larger cam. Just wondering if these guys that want to do heads and possibly upgrade turbo's know that new injectors might be on the list as well as a new chip. I am running the TE44 and stock injectors, but if I were planning on doing the vortec's I might consider having to go with larger injectors as well. Since these heads flow so much more, and a bigger turbo flowing more... well it seems obvious why the trucks with FAST and a cam are running huge injectors.
Scott
Scott
With FAST, you run huge injectors cuz you can. If drivability and low pulsewidth accuracy issues didn't exist in large injectors, you'd run 160lb/hr. With FAST, you can control the fueling very well. I tuned the Sy at McCoy's with 83# injectors. If you jumped in and started it up, you'd think it was a very well tuned stocker. I'd try running 55s or 65s on the stock ECM, but it's a pain to have the injector drivers swapped, as well as injector wiring changed. I did run 55s on the stock ECM for a short time.
The accuracy issues -
Ok, very large injectors are going to be inaccurate at low pulsewidths, as well as non-linear. You want to get injectors that are matched, so you get equal fuel distribution at WOT. At static conditions, injectors vary more than they do at lower duty cycle, so it is better to run a matched set at lower duty cycle.
I have no idea what the duty cycle would be. 50# injectors, running static, should support 600hp, so you can do some simple predictions.
Ok, very large injectors are going to be inaccurate at low pulsewidths, as well as non-linear. You want to get injectors that are matched, so you get equal fuel distribution at WOT. At static conditions, injectors vary more than they do at lower duty cycle, so it is better to run a matched set at lower duty cycle.
I have no idea what the duty cycle would be. 50# injectors, running static, should support 600hp, so you can do some simple predictions.
Well I think this really helped quite a bit.
http://www.turbobuick.com/forums/showthread.php?s=&threadid=23483&highlight=duty+cycle
As for using the larger injector at low pulsewidths, seems like FAST would be the way to go since it sets the fueling so
accurate.
To stay with the stock ecm...
The peak and hold injectors (55 and larger) would possibly be better in low pulsewidth conditions, but would require the new injector drivers. I don't know what that would involve.
I like the comment about using *stock* like pulsewidths with the ECM...something about not letting it know whats *really* going on.
Sorry if this is off the topic here, just wanted to share this info I ran across.
Scott
<font size=-1>[ This Message was edited by: kwick6 on 2002-01-05 23:43 ]</font>
http://www.turbobuick.com/forums/showthread.php?s=&threadid=23483&highlight=duty+cycle
As for using the larger injector at low pulsewidths, seems like FAST would be the way to go since it sets the fueling so
accurate.
To stay with the stock ecm...
The peak and hold injectors (55 and larger) would possibly be better in low pulsewidth conditions, but would require the new injector drivers. I don't know what that would involve.
I like the comment about using *stock* like pulsewidths with the ECM...something about not letting it know whats *really* going on.
Sorry if this is off the topic here, just wanted to share this info I ran across.
Scott
<font size=-1>[ This Message was edited by: kwick6 on 2002-01-05 23:43 ]</font>
