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View Full Version : How high to spin Vortec 4.3

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05-23-2006, 09:31 PM
To what rpm can you safely spin the 99+ 4.3 vortec?
bluecajun5.3
05-24-2006, 08:08 PM
i've rode in a couple of 4.3's and i can say that i feel them stop pulling around 5300 to 5500.
Rhino79
05-25-2006, 10:29 AM
I'm with cajun, they make their peak at about 4600 RPM stock so 5000-5200 would be a good shift point.
blk_blazer00
05-25-2006, 01:58 PM
:werd:
zippy
05-25-2006, 02:47 PM
The bottom end is good to about 6200.
03sierraslt
06-09-2006, 05:37 AM
Ya I had one some time ago and I used to beat the crap out of it, I used to take it to 6000 all the time. Not saying this was utilizing its power curve effectivly but the engine never skipped a beat. Maybe a little valve float...
nekkidhillbilly
07-13-2006, 04:08 AM
dads redlines at 5500 rpm from the factory
silver-mod-o
07-13-2006, 02:20 PM
I would shift mine pretty high too.. up around 6K I know it was just making noise, not power LOL...
bluecajun5.3
07-13-2006, 02:51 PM
I would shift mine pretty high too.. up around 6K I know it was just making noise, not power LOL...
:jest: i know first hand from someone else near you.
silver-mod-o
07-13-2006, 07:21 PM
:jest: i know first hand from someone else near you.

yeah no joke.... LOL... he beats the piss out of that truck LOL... :jest:
extendocab
07-13-2006, 08:25 PM
yeah no joke.... LOL... he beats the piss out of that truck LOL... :jest:

Who you talking about..... :secret2:
I spin mine to about 6000 but it falls off at about 5300-5400, but when it shifts its start right back up....
zippy
07-13-2006, 11:10 PM
Factory redline has nothing to do with how high you can spin them. The cam and valvetrain are the main deciding factor there up to around 6k or so. The stock intake is pretty inefficient past 5500.
dirt track racer 81
07-14-2006, 10:52 PM
Ive seen one of these 4.3's in a IMCA modified (thats a type of race car) turn 7000+ rpm and he was out runnin 383's and 406's all night long
silver-mod-o
07-17-2006, 03:12 PM
that definitely had to be a built motor... there's no way on earth that motor would do that stock.
dirt track racer 81
07-17-2006, 08:20 PM
that definitely had to be a built motor... there's no way on earth that motor would do that stock.
it was built..old nascar busch motor when they ran v6's years ago. its the same motor as a 350 just minus 2 cylinder..
silver-mod-o
07-18-2006, 06:54 AM
Yep :D they are neat little motors if you like to tinker.... its hard to make big power without f/i of some sort though...
Snake Eater
07-19-2006, 11:13 AM
There are quite a few 800+rwhp Syclones out there. 4.3's can be sweet motors.
blk_blazer00
07-23-2006, 11:39 PM
hell yea they can. go on s10forum.com and poke around and ask the guys about some of their trucks. i think they are the best 6-cyl motor ever made
AceHaag
07-25-2006, 03:53 AM
There are quite a few 800+rwhp Syclones out there. 4.3's can be sweet motors.

These truck have turbos. It makes a huge differance:judge:
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