hmmm remove weight from in front of the drive wheels...sounds like a way to remove traction....though with the alum heads you could bolt the two cast iron units behind the bumper and gain traction....
yes there are many benefits to alum heads but remember that alum castings tend to relax when seasoned and can have lowspots (look at the Chrysler castings (2.2 2.4 and 2.5, GM 2.2L heads, Ford 3.8L (which still have problems even with MLS gaskets), Chrysler 3.3L and 3.8L (ditto).
Not to mention that the clamp load of alum heads sux with only 4 bolts per cylinder, even though we have "only" 3.8 inch bores, our head bolts are located pretty far apart so under cylinder pressure spikes the head will lift, even if we managed to fit 1/2 inch studs, now if they found a way to put an additional 2 bolts per cylinder this would be greatly reduced but I don’t see anyone working an an alloy block, though TA performances alloy block casting is a possibility the casting would have to be modified a bit and drilled in the SI/SII 3800 specs.

but remember the more weight you remove from in front of the drive wheels the worse your 60'* will be without full on Pro FWD 4 link front suspensions and massive slicks. Though like i said you would be able to bolt on the ballast at the extreme front of the vehicle and be all the better for it. Though that same weight with a cast iron headed engine would be even better... at the least it would lower the vehicles center of gravity a small bit. i see this being more of a benefit to the Fiero crowd.

also realize that a thermodynamic engine gets more efficient the more heat is retained in the combustion chamber as opposed to being lost out of the cooling system (detonation causing hot spots not withstanding) alum heads are a great bandage for an inefficient cooling system and poor combustion chamber design, more could be done with the cast iron heads if a reverse flow cooling system was utilized, that and a nice direct injection setup for less chance of preignition (look at the newer designs).

All modern pro stock (and other Max effort) engines use alum heads with a thermal barrier coating to help keep the heat in the combustion chamber, which cast iron heads are good at naturally, so yes if you had the alum heads with the thermal barrier coatings, you would be on par, but the cast iron heads treated would put them above the coated alum heads again, while lowering the chance of preignition hot spots forming.
and regardles the spark plug electrode is a large part of that issue, which can be cut back to reduce this possibility.

the biggest improvement would be a better splayed/canted valve arrangement with shaft mount beam type rockers or a hemi type valve layout, also remember that most cast alum heads have smaller water jackets for thicker alloy to maintain strength on par with cast iron.

The largest benefit i see to these is head flow rates much better than the OE cast iron units, which is as it should be for aftermarket heads, but remember that the SII engines have a very large inherent inefficiency at high rpm cylinder filling, it'* horrible rod/stroke ratio/angularity which greatly reduces cylinder filling ability at high rpm'* as well as greatly increasing internal friction exponentially at higher rpm'*.
the short rods of the SII 3800 that give it it'* excellent low rpm Tq hinder it'* ability to make power up top, where as the SI'* ability to make top end power is severely limited by it'* poor cylinder head design.

this is why i think a SI/SII hybrid is the best of both worlds, and a stroked tall deck SI shortblock with those heads (in a high port design if not a canted/splayed valve arrangement) would be the perfect setup for a max effort 3800 engine buildup, with great mid and high rpm power potential, but cylinder head clamping would have to be addressed, just look at the 6 bolt per cylinder GN 3.8L max effort engines.
I could also see a better transaxle longevity with less low rpm Tq and traction limited launches. a max power engine is looking at the whole package, desired power and operating rpm'* those high flow heads while good wont be fully utilized by the poor cylinder filling ability of a short deck short rod engine.

those are my thoughts on this anyways

Regards, James

Wow. Ever hear of the 3400? I've had a couple cars over the years that warped heads. 3 or 4 probably. All were aluminum heads, all were different makes. And the new aluminum head engines are DESIGNED for them, with more bolts per cylinder to hold it flat during thermal cycling. Now add some high effective compression from a supercharged engine. You'll want ARP studs on this install.

These are for the hardcore track junkie with a fat wallet.

I understand that there are drawbacks to aluminum heads on an iron block, but everyone here just instantly strikes down Al heads with no questions asked. They're not that bad. No, they might not make it 300,000 miles without head gasket failure or warpage, but they're still better for zoom-zoom. I wouldn't recomend them on a daily (repeat DAILY) driver, but they're fine on a show / track / Sunday drive / "non primary transportation" car. Now, when I mean daily driver, I don't mean a streetable car, I mean a true grocery getter.

And, what'* this with thinking that the Al head'* lighter weight will cause decreased 60' times and less traction? If, of all cars, a Bonneville doesn't have enough weight over the front tires, I don't know anymore. Grand Prix GTP'* seem to do fine. If Bonnevilles needs more weight over the front tires, then why not strap sand bags onto the hood? Better traction and 60' times will result. I think that any L67 powered car would do fine with lighter weight aluminum heads. But that'* just my crazy thinking.

I believe that head failure is a result in direct relation to poor engineering. In my application, I have 10 bolts holding down 4 cylinders at a 9.0:1 CR. In 183k miles, the heads have never been removed from the block. I can not argue the point about less weight in the front of a FWD car, but it has been my understanding, that aluminum is lighter, easier to work with(porting/machining), and as stated, disipates heat faster. James states that race engine heads are AL with a coating to retain heat in the combustion chamber. So the solution would be to coat the heads and run them. Personally, I would wait until they have had a few runs through the mill and are known to last 100k miles a lick. Just my two pennies.

While there are definately some advantages to an aluminum head such as those mentioned above the MAJOR advantage in OUR application is to the ability reroute and change coolant passages to allow for betterflow cooling and more importantly more room to open the heads up for better airflow without cutting into the coolant passages as would happen on normal heads.

These could be a great boone for performance in the 3800 community, if they are done right.

Everyone knows the drawbacks to aluminum heads. However, with the price tag that is going to go along with these heads, we know they are for someone who is very serious about making their car go fast. If done right, these heads will be an excellent solution for someone wanting to go fast in their 3.8, they should have tons of advantages over the worked over stock heads people are using now.

The drawbacks are obviously going to have to be dealt with but really with as cool as most run their 3.8'* I can't see overheating being much of an issue. With the additional head bolts ZZP has been adding to some of their headbolts, this should help with a lot of the issues.

Also FWIW, my STE has iron block and aluminum heads, and with only 8 head bolts per head, I've had absolutely no head issues at all with a hair over 9:1 compression and 14psi boost. (keep in mind this setup only has 4k miles on it, 3k of which I was only running 8psi, I just recently made the slight jump from 8-14psi. ) I'm sure my 160 tstat probably helps with that a little but not a lot. As soon as I get the transmission issue worked out and I shove the turbo I want on the thing, it should be seeing somewhere in the 18-20psi range and I forsee no issues with the heads. I'm also considering getting some thinner head gaskets to bump the compression up to the 9.6:1 range.