Project 3400 Roller Cam Block (Page 26/82)
lou_dias JAN 23, 11:44 AM

quote
Originally posted by DefEddie:
I've got a set of genII's from a tgp if you want to see pics.


Sure! Do you have pics of the GEN2 lower intake?


@Will
So the GEN2 lower intake would interfere with the roller lifter guides?

[This message has been edited by lou_dias (edited 01-23-2013).]

Will JAN 23, 02:15 PM
I don't know about that, but the LIM and UIM for the Gen II heads is asymmetric...
The Gen II plenum is offset toward the rear bank.
That means that the forward bank and rear bank runners in the LIM are different lengths. They are different lengths in the UIM also, but the differences are opposite, so that the assembly of LIM + UIM has the same length runners for all cylinders.

Just go with the Gen III/IV heads/intake... they are proven performers
DefEddie JAN 23, 02:25 PM
Just tell me what you want to see.
I have the upper,lower and heads from a tgp.
Also have the tgp shortblock on the stand,currently prepping genIII heads for it.
Also have a big journal non-vvt 3500 complete except upper manifold.
DefEddie JAN 23, 02:52 PM
This is the genII tgp heads and a genIII 3400 head.
The genII's are fresh from blaster and have been ported,genIII head has been coated but are not ported.
I'll post up the lower for you in a few,it needs cleaned up as it has been acid ported and i've yet to blast it off.
lou_dias JAN 23, 03:48 PM
Thanks! I'll have to compare the intake ports to the GEN1's I have in my basement. I don't see a different in the exhaust ports...I had my GEN1 exhaust ports ported to 1 3/16" looks like your ported GEN2 heads are ported close to that. As for the intake, the splayed valves required the change of the shape, on the GEN3, it just looks like GM opened them up a bit mor then machined in the D port shap for some extra volume. I'm suprised they didn't just keep them round and port them bigger. If you look at PAGE 1 of this thread you'll see the porting I had done. After I pulled the heads once more, I had additional polishing done.

So other than the combustion chamber re-design...allowing for 1.76" intake valves, I don't see the big deal... I'm sure the heart-shaped chamber helps with the flamewall front but I do have my spark plugs indexed (facing the exhaust valve) so meh. I still say the roller cam and it's inherent reduced frictional losses is the single biggest factor in the difference in performance. The second being the higher compression ratios of the aluminum head motors. 3rd would be the freer flowing intake. I don't think when ported properly and polished that the heads themselves differ much in flow and that the differences are more to accomodate the intakes other than the change required by the splayed heads.

That said, I'd still love to save the weight. Do you have weights for those heads?




I believe Falconer ported iron heads got rid of that "fin" on the intake port by I instructed my machinist to just polish it. Other than that, I'd say he removed as much material as the Falconer iron heads... Even my machinist knew better based on experience he had with other engines/heads (about the fin).

[This message has been edited by lou_dias (edited 01-23-2013).]

Will JAN 23, 04:00 PM

quote
Originally posted by lou_dias:

I don't think when ported properly and polished that the heads themselves differ much in flow and that the differences are more to accomodate the intakes other than the change required by the splayed heads.



What makes you think that? I think that flow numbers and dyno sheets say otherwise.


IIRC, bare aluminum heads are 13# each, bare iron heads are 26# each... right at 2x the weight. That makes ~25 lbs of overall weight savings available.
lou_dias JAN 23, 04:11 PM

quote
Originally posted by Will:
What makes you think that? I think that flow numbers and dyno sheets say otherwise.

IIRC, bare aluminum heads are 13# each, bare iron heads are 26# each... right at 2x the weight. That makes ~25 lbs of overall weight savings available.


Thanks for the weights!

What I mean is I don't think "stock" GEN3 heads are much better than properly ported GEN1 heads for power:
http://www.youtube.com/watch?v=lCKRYk4YbRA
170.4 hp/193 ft/lbs thru a manual (probably F40 like me) and I did 187/249 using the stock 3400 cam with the Fiero intake...though I doubt he has a 2.5" exhaust like me... and I hope to get my car back in April and can post a proper dyno of the tuned Trueleo intake on the motor.
Will JAN 23, 04:44 PM
The Gen III heads/intake have also done 270 RWHP on a 3400... so I think the potential is far greater in the Gen III heads.

Think about what you just said... your ported iron heads are probably pretty much equivalent to as-cast Gen III heads.
DefEddie JAN 23, 04:59 PM
I will weigh the gen II and gen III heads when I get a chance.
I have a set of bare 3500 heads as well,and assembled 3.4 heads.
The genIII are currently set up with the break-in springs as I am using the TGP bottom end with a ceramic coated flat tappet cam.
The combustions chambers are being coated and they need to be assembled,don't really wanna pull them apart again.

The D port enhances flow,if you look thru your valve and out the intake where it comes into the bowl I bet it will look similar.
Most port work ignores the floor other than cleanup and reshaping is mostly to enhance the short side radius to a nice profile.
That is advice from someone I trust that does it for a living.
He said the ideal is if you can recreate the curve from a 4" diameter circle into the short side radius.
He does have extensive experience with the superflow and engine dyno at his work testing,but not with anything other than nhra stuff.
lou_dias JAN 24, 12:44 PM

quote
Originally posted by Will:
The Gen III heads/intake have also done 270 RWHP on a 3400... so I think the potential is far greater in the Gen III heads.

Think about what you just said... your ported iron heads are probably pretty much equivalent to as-cast Gen III heads.


I'd love to see a list of mods on the car that put down 270rwhp...got a link?

On the intake side, the angled push rods mandated the reshaped intake ports. On the exhaust side, round was good enough for GEN2 but it looks like in order to increase exhaust flow they machined in a sort of squaring off on one side since simply making ALUMINUM head exhaust ports larger wouldn't have improved flow because of the angle the air is coming out at. For iron heads, a simple larger diameter port and polish is sufficient to achieve the same effect volumetric effect in flow. In the end I think the only debate is how big an improvement the combustion chamber is that mandated the intake and exhaust port change. Properly indexed spark plugs probably minimizes that difference and to me the heart-shaped chamber would cause more of a pressure imbalance on the piston...