alright, always alot of talk about how the fwd heads flow better, so I set out on a mission today. To find fwd flow numbers.

I found some, WOOT.

Rather then make all of you guess. On the hypothetical desktop dyno (which we found isnt exactly right).

stock 3.4 setup.
160@4500
200@3000

3.4 with gen2 heads (um, 87-92'ish fwd)
171@4500
227@3500

3.4 with gen3 heads (this is guess from gm's claims of how much better they are. 2000+ 3.1/3.4fwd)
182@4500
233@3500

All this UNPORTED!!! this is casting flow numbers.

Yes, I'm missing between 93 and 99 as gm put gen2 on some engines, and gen 3 on some engines.

So you can net est 22hp and 33tq buy going to fwd pistons, heads, intake, and re-programing the ecm, and figuring out how to make a distrib work on a fwd intake.

Piece of cake right

 

Or just buy some Supersix heads that will entirely outflow the gen 3 aluminum heads.

you can't beat bench flow ported heads. You can not port heads yourself unless you have the equipment to test flow and have experimented on what angles get the best results.

Everyone that has claimed to have "ported heads have so far as I've seen done it themselves. Heads ARE in fact what make HP. Have them professionally done with flow equipment and you will really truely see performance gains. They are increasing intale port flow from 129 to 165 with the 1.8" valves. Thats about a 25% increase on the intake side which we need badly. Hence why the single profile cams show better gains when the intake lift is as high as the exhaust (unlike V8's which generally need exhaust help.) The duration of intake lobe we have to run to compensate for the intake port restriction makes the vacuum go to help and messes with the computer.These heads can pull a larger intake charge on a shorter duration cam.

Supersix heads with 1.8" intake valves is next on my purchase list, (I am finally at that point with this car and begining the motor build. Evrrything else is finished.)
And then the 1.6 aluminum gold roller rockers and pushrods.

I wil say again to everyone else reading this-

Heads are what make power. Without good heads, you can not make power unless you force the intake charge into the chamber like Doward. This is where anyone should put there money if you are truely wanting to get noticiable HP gains when building any engine.

 

the supersix ported heads with 1.72/1.42 valves flow compareable to stock fwd heads. I have yet to find any worthy ported fwd head numbers.


Also, didnt mention. The fwd heads are capeable of more lift w/o sping/coil bind. Not much, but some.

 

just FYI (not trying to start anything), my heads were home ported and run on my flowbench. i don't have solid cfm numbers but i did prove to myself that they flow better than they did stock. dale is right, stock FWD heads can flow atleast as well as ported RWD heads. however, the ported RWD head swap is a lot more simple than swapping to FWD heads.

 

where can you get the supersix heads from?
and how hard would it be to swap in the fwd heads?

 

supersix heads are from supersix motorsports. i think that they are in CA but I could be wrong. their website is www.supersixmotorsports.com
aluminum heads aren't a real simple swap. you have to change pistons to keep compression to a reasonable level. a new intake manifold is required (and in the works). the exhaust bolt holes are about a half inch further apart (vertically) than ours. and, a new alternator bracket is required.

 

it doesnt have a price for heads for the 3.4 RWD on their website, has anyone contacted them to find out how much they are? im going to send them an email and find out what they run.

 

that would be a complete biotch to deal with the fwd intake base and a rear wheel block in respect to the distributor. the only i could see doing it is eithor go with a distributorless ignition or a custom made intake base which would be a pain in the a$$ and a fortune due to the water passages

 

Jay, How are you figuring this. Is it just of of Valve size? You have to have CFM flow #'s from the individual intake ports.

Alan, you said you have a flowbench at home? (wow, nice toy, you should go into business porting heads.) what #'s did you get after your porting job?

Supersix also belnded the bowls, cc's chambers, and machines the valve pockets to take any lift you want to through at it. There is plenty of meat on the 3.4 cast iron heads, not so for the FWD aluminum heads. This is why you never see aluminum factory heads being used in midget racing. They all are running Porter custom made heads- which I still can not find any info on how to get.

 

Dean, yes I have true flow numbers on the gen2 heads. AM91 now has the same link.

Now for the gen3, gm said at .450 lift, it gave xx% better flow in, and xx% better flow out. I evened that % out on the numbers below, and kept that same % on .50 and .55 lift.

The gen3 head did get a 1.76 intake valve. Same exhaust valve.
The gen3 also got roller 1.6 rockers, which gen2 and ours didnt.

I'm not trying to start any arguments. I just kept hearing how better these heads are, so I did some hardcore hunting, and finding some info.

As cool as a FWD intake would look under my hood, I think I'll stick to the same setup, but just with better heads and hopefully better intake and cam eventually.

 

every track that i have ever been around has a flea market in the early spring before the season starts, when we had parts we couldn't use off the sprint cars, we would take them to the fleamarket and sell them for as much as we could get for them. chances are the midget guys do the same thing. i am thinking the same thing that you are on this one. i want a set of those heads, but i can't find them eithor. are you sure that they are porter heads? did you try to contact porter? someone's got to have a set lying around that they can't use anymore or something!

if you happen to find a couple, pick a set up for me. i will do the same if i can find a set. \
i just emailed a buddy back home and told him to keep his eyes out and if he finds some, to pick up as many as he can, that i will pay him for them when i get home.


i think for this one if you seriously want a set, like i do, that we are better off pooling our resources for a common goal

 

CORRECTION!!!

That was a gen3 head that I got flow numbers from. Or so my sources say.

So when I get home, I will re-compare the numbers and edit my orginal post.

 

Speaking of supersix heads how much are they and what gains will u see on a pretty much stock 3.1 engine

 

i sent an email to them, but havent heard back yet

 

I love the 60* V6's. I played around with the idea of putting one in my 82 Z but came to the conclusion of it being more trouble than what it is worth. Because of having to change springs and putting a V6 ECM in. Since the car is carb'd. Any way, this deals more with the FWD's but some of it is relavent here. A nice chart with compression, bore X stroke, valve size an HP + torque. A little futher down in the "Why swap to Gen III engine parts?" section tells the fow ratings of the GEN 3 aluminum heads over the GEN 2 aluminum heads.

http://domesticcrew.com/faq.html

converting HEI distributer to DIS:

http://www.60degreev6.com/index.php?...is+pins+module

The hardest part of this would probably be setting up a crank trigger or something along those lines. Unless the the RWD 3.1 used DIS then you could use that block as a nice starting point or a RWD 3.4 block. Of course that won't be cheap. But real performance isn't cheap.

 

The info I have on the gen3 aluminum heads gives them a comparison of 16.7% more intake flow than the stock HO cast iron gen1 heads.
HO iron heads have a 1.72" intake valve
gen3 alum heads have a 1.76" intake valve.

The gen3 heads have a 31.7% better flowing exhaust flow though than the stock HO heads.
I'll amake some quick clculations and post more.

 

Stock HO iron heads
1.72"i/1.42"e valves
max flow at .450" lift- 128/120

Alum gen3 heads
1.76"i/1.42"e valves
Max flow @ .450" lift- 149/158

Supersix ported heads-valves unshrouded
1.72"i/1.42"e valves
max flow at .470" lift- 151/145

Supersix heads with larger intake valve
(heresay, but Tom claimed in an e-mail that the 1.8" intake would yeid aprox 25% gain over stock)
1.80"i/ 1.5"e valves
max flow @.470 lift- 160/150

That is a .440/.440 single profile cam grind with 1.6 rockers yeilding a total lift of .470"i/ .470"e and still computer friendly.

 

dean, you asked about my numbers... the flow bench isn't completely finished (just far enough to run some "comparison" tests). I don't have solid cfm numbers yet. I do have the raw numbers from the manometers though...once I get all of the software/formulas worked out, I'll be able to plug in my raw numbers to get the cfm.

 

Supersix is in GA.

 

i just talked to tom at supersix, they dont have cores in stock, but if you send your heads to them, they will P&P, 3 angle valve job, comes back completely assembled w/ Comp Cams valve springs. you have to pay shipping. without shipping is $850 for it. i dont think thats too bad really.

 

Will the supersix heads do anything to your compression?? Any idea on hp/tq with the supersix heads?

 

if you have them milled then it will bump up your compression. they do that for free while your heads are in there, .010, .020, .030. but it wont be a drastic change in compression though.

 

What? nevermind the fact that the intake base has to be milled, as well??

I'm confused that a company that 'specializes' in 60º V6s wouldn't know about a little problem like that!

 

IIRC from my performance engine machining class, you can get away w/ going .010 w/o milling the intake. they may mill the intake too if you talk to them about it, i dont know.

they arent just 60 degree v6 though, they have the 3800 and ford setups

 

i concur with drdave on this one, though my automotive work is not as much as what it should be(amount of jobs completed)
any kind of machining on the heads that affect the seating surface will throw the bolt holes between the intake and the heads off. that may not seem bad, but anything in my opinion more than about .005" and you run the risk of blowing gaskets.
bad ju ju. if you want more compression, get longer pistons, get a stroker kit. yes you can still stroke a 3.1. any good machine shop should be able to modify your crank throw to do it, though it is gonna be costly. to get 11.5:1 that is what i am gonna end up doing, cause i really don't feel like modifying the rest of the engine to get it(dropping the deck and the heads and the intake. that would cost me more yet even if i were to do it myself(fun but too much of a nightmare for setup on a conventional bridgeport mill and a flycutter without power feed.

 

if u mill it .10 what will it make the stock compression go to? 8:75:1?

 

take .01" off your compression height and do the math, i dont' have the formula close by, but it should be something like
(D*Pi*H)/(d*Pi*h)
H=height at full extension(down stroke) of piston
h=height at full extension(compression) of piston
D=diameter of cylinder

 

isn't that for deck height? ...of the block? for heads, you have to know the cc of the chambers. that's to too easy to figure with an odd shaped chamber. ...without actually measuring it.

 

yes alan you also need to figure in your head volume in there too, i was just giving a example of about what to expect from the formula. i just drew that up off the top of my head while i was sitting here. if i am correct i believe that all the 60* heads (not counting the fwd engines) have 50cc combustion chambers. i can't remember the conversion constant for metric to standard off the top of my head, but that number should be added to both sides of the division symbol.
just out of curiosity does anyone know the deck height at bottom dead center, top dead center? i am trying to calculate what compression ratio my engine will be using the 3.1 crank with the 2.8 pistons and conn rods. it shouldn't be the same compression ratio because both engines have the same compression ratio from the factory even though the 3.1 has a longer throw. that means that the pistons have to be a tad bit taller on their own for the 2.8 and the 3.1 pistons would have to be a tad bit shorter.
goal here is 11-11.5:1 compression

 

you will get that compression...as long as you don't throw the pistons into the heads... 2.8 pistons apparently have the wrist pin located lower than 3.1s. or just the strokemakes too much of a difference. I tried pistons out of a 2.8 when I was building the motor that I am running now; had about .100" pop-up.

 

ooohhhh don't want popup. what did you do to make your cr 10.75:1 cause i don't have much more to do than what you did and i got 11:1 which is acceptable for me. sounds like i am just gonna have to go with a custom set of pistons. i was trying not to go that route(800$+ out of my pocket for that one.)but looks like i will have to with over .500 lift to keep a dispute from happening between the pistons and the valves

 

i had to go with "custom" pistons.

 

thanks alan, much appreciated