1980RS wrote: ↑Wed Apr 07, 2021 8:28 pm
If people think a stock 5.3 out of a 99-05 truck is going to walk away from a SBC 350 Vortec engine, that's a laugher in my book.
Like many things in life, you have to read the rules. ANY stock LS head AND a 4bbl carb on the 5.3. SBC gets a 4412 500cfm 2bbl and a cast iron 2bbl intake. And there's a couple of claimer rules in there, too. Go ahead, put $5-10K in a SBC and let someone claim it for $500 after the first race.
Well that sucks, someone in the sanctioning organization afraid people might go too fast?
Yes they are B mods. And street stocks.
What your looking for is modifieds and super street.
What would be the ideal head for the 5.3 in this situation?
3/8 mile dirt track,
Likely run a E-85 gas, such as what's available through VP race fuels.
Max compression between 9.5:1-9.7:1
rickb33x wrote: ↑Fri Apr 09, 2021 12:38 am
What would be the ideal head for the 5.3 in this situation?
3/8 mile dirt track,
Likely run a E-85 gas, such as what's available through VP race fuels.
Max compression between 9.5:1-9.7:1
I would think E-85 would hurt an engine with low compression numbers like that over pump gas. Guys where I live will not run E-85 with less than 12:1
We are allowed porting, bigger piston bore size(must use the 3.622 stroke though, rpm range is 3,200-6,800 I believe on a 3/8 dirt oval (7,000rpm pill).
rickb33x wrote: ↑Fri Apr 09, 2021 12:38 am
What would be the ideal head for the 5.3 in this situation?
3/8 mile dirt track,
Likely run a E-85 gas, such as what's available through VP race fuels.
Max compression between 9.5:1-9.7:1
The 706 heads have the smallest combustion chamber for the most compression and they flow well, especially ported, with their small intake valve so, that would be my starting place.
Premium pump gasoline should be fine at that compression ratio; E-85 will lose power.
rickb33x wrote: ↑Wed Apr 14, 2021 1:53 pm
706 with 2.00 intake and porting is what I was thinking but to what extent? exhaust is pretty much open and with little restriction.
A 2.00" intake valve is a bit large for that 3.780" +.020" bore size. The 1.890" diameter intake valve is not that bad.
About 1.940" is the "largest" head diameter intake valve I would use with that bore diameter; the chamber can be bigger than the bore if there is an angled transition at the top of that bore. That valve edge doesn't actually get INTO the bore till after about .450" valve lift.
rickb33x wrote: ↑Sat Apr 17, 2021 6:29 pm
So do port work with the 1.89 intake? will the head flow close to 7000 rpm?
Certainly ... this is only about a 327 cubic inch engine.
Circle track engine or otherwise, this is looking interesting as a street build.
Where would one get the details on what needs to be done to the 706 heads? I have two LM7's fitted with these heads and one is a potential donor for my "road" car.
