3.4 head porting: FACTor MYTH

[whiteThunder]

so i today to 2 diff places, and here is what i have been told:

1. the head vin casting says that its 2.8 (if that matters, i don't know)

2. Both places don't want to touch porting the intake manifolds, they said it won't be worth much.

3. Both said that the vanes should be removed, though i want some to stay intact, and they don't want to enlarge the exhaust openings to match the headers. He said that you want it to go from small to large.

4. Lastly, i was told that they will just grind out imperfections, and that not too much can be taken out with out hitting that water jacket, is this true?

5. Lastly, one guy said that without putting in larger valves, porting is pointless? super six uses stock sizes on their heads, 1.4 and 1.72 i beleive. Has anyone done larger valves?

Basically, both said that extensive porting is kind of wasteful, and that a good resurfacing, mild port and polish, and 3 angle va;ve job will be good for 15-20 hp. I think i just might have the guy take the vanes out because with a huge cam, i need to flow some serious air. Has anyone had their upper and lower intakes done, if so did they take out a lot?

[wolf]

1. all iron heads say 2.8
2.true except where the lim necks down, you wanna port match it to the head
3. i'd kill the vanes
4. true, not much material in the iron heads, but the little things help these heads alot

5.I wouldn't mess with bigger valves, but if you want the most you can get, use the ssi swirl finished valves I have in the red camaro, and have the valve seat radiused( they have a 5 angle stock, so a 3 angle is acually hurting it)

[whiteThunder]

thanks, i don't want to get shafted here. what is the lim, where it bulges out for the spark plug?

[wolf]

oh sorry, lower intake manifold.
the fiero store hase the si valves for 160 bux

[viper98885]

You can definitely port the intake and exhaust runners pretty good. We offer P&P head packages if you are interested that would solve a lot of questions or concerns that you may have. Let me know if you are interested.

[oil pan 4]

You can tear a lot of metal out of the heads with out hitting the water jacket. Like making the port taller, guess what no water jacket up there, just watch the bowl.
The exhaust ports are thick, but you don't want to make them a hole lot bigger unless you have big header and will be running nitrous.
Those heads weigh 25lb for 3 cylinders there is plenty or metal.
I going for turbo so I just made mine flow as smoth as I could.
Bigger valves, not for any thing that will be run on the street.
If I was going to make a big nirtous engine I would leave the intake alone and stick a bigger exhasut valve in there.
Take out the vanes if you are going to run after market injectors that atomize better then the stock ones.
Not porting the intake manifold, well if your going to stick a bigger tb on there it is kind of a must.
Have you ever seen the stock 3.4 intake manifold?
Well here it is
I'm guessing they haven't done to many 3.4 heads.
The only time I would go for a mild port is if the engine was going to be fed by some thing other than 14.7PSI absolute air pressure.
Rember were talking about heads that flow 117cfm stock.
If you are going to be n/a you will have to flow more than that.
Excuse me while I whip out the hp calculator.

[oil pan 4]

Well a stock flowing head on a 3.4L.
They flow up to 117cfm at .4'' even higher lifts yeald 117cfm or less.
So a 117cfm head on a 205ci will have a max hp pontinal of 180hp @ 4500rpm.
It all most looks like GM did there home work.
This thing is good, that is all most precisely what would happen if you stuck a bigger cam on a stock long block.
hmmmm... A 205ci, 9.5:1, 4500rpm engine would make 160hp, [img]graemlins/bowdown.gif[/img] it's close enough for me.
Now up the head flow to 140cfm (not to insane of a port job, still kind of mild). You get Max hp potenital of 216 @ 5400rpm.
Then plug 205ci, 9.5:1 c/r and 5500rpm into the rough engine calculator and you get a little less then 200hp. That's a rough calculation.
That is what I'm going for, that with an 272 cam is all most a perfect match. I was guessing about 200hp and 240tq.
Go to 150cfm and I get 231hp @ 5800rpm.
That is matched with the right cam(biggest possible) and stuff.
I like these calculators I plug the head cfm, 383ci, cam, c/r, intake and stuff into these different calcs and I get 475hp to 500hp for my z28 engine I'm slowly peiceing together [img]graemlins/rock.gif[/img] .

[whiteThunder]

thanks guys, i will insist on full port job, enlarge the exhaust openings just a tad, but deffinately not too big, and hopefully remove the vanes, get some blending done, make ports taller, and get 140 cfm. What do your packages run Viper? please let me know asap, because i am getting this done later this week. also, how fast is your shipping, i need ur vavletrane package once my check gets here? what numbers is everyone's heads flowing

[whiteThunder]

also, the ssi valves are worth it, or not really. i may go nitrous, but if i don't, would these bigger valves mess things up for a street driven car? should i just go exhaust, or intake, or both.

[viper98885]

Originally posted by whiteThunder:
What do your packages run Viper? please let me know asap, because i am getting this done later this week. also, how fast is your shipping, i need ur vavletrane package once my check gets here?

Stage 3 P&P head work is $649.00 + $60.00 refundable core charge. Also, with purchase of P&P heads and valvetrain package, we assemble the heads for you free of charge.

[whiteThunder]

Can they do my intakes, what does the stage 3 come with, btw the guy doing my heads is going to clean, prime, and assemble allf or free. how long does it take?

[oil pan 4]

[img]graemlins/barf.gif[/img] :eek: [img]graemlins/omg.gif[/img]
Don't post your prices when I'm drinking, all most made me spary my computer.
What's ssi valves?
Did some more math, a 205ci that makes peak power at 5500rpm, with say a crane 272 (or equal cam) on good ported heads with a c/r of 9.5:1 with 24lb/hr injectors would be matched up very well(my engine set up, well minus a little of that c/r).

[wolf]

si valves (i typoed earler)
http://www.sivalves.com/
you can order them thru fax there or go to
http://www.secureleadercom.com/fssto...Bit=3&dept=194
and look for Part # 52876

[black34v6]

or if you live 30 mins from Simi Valley you could go pick them up too ;)

lol.

im always surprised how many shops are here in So Cal.

[whiteThunder]

will the valves be worth it? are they the stock size?