Sierra6

So I just got my heads in from someone who did a cleanup job on them and finned the intake vanes slightly. What is the max valve size that I should have put in them? I'm thinking I might as well go with stainless valves. Also, should I ask for a 5 angle valve job?


These heads are for my turbo build. I've already received John's Turbo kit and I will be modifying it to use a header on the driver's side instead of the manifold.

Six_Shooter

iTrader: (2)

Honestly, increasing valve size idiot going to gain you much, if anything. The iron heads just don't flow well, even when ported. Just put stock valves in and be done. The turbo is going to give you every bit of power you can get out of an iron head engine.

Sierra6

thanks for the advice. i've seen it stated on here by the guys who've done it that ported iron heads on a turbo car do net worthy gains.

Six_Shooter

iTrader: (2)

Yes, porting will have gains, but not nearly as much as going to gen3 heads (even gen2 are better than gen1). The work involved in increasing the valve size in the iron heads is not worth the net gain. For that kind of effort and expense the gen3 heads just make far more sense.

So basically do some mild porting, use the stock valve size and turn up the boost, that's what's going to give you the best results on iron heads. Anything more is just a whole lot of effort and expense that would be better put into other heads/top end.

Sierra6

I didn't know how much more work it is to put larger valves in as opposed to putting stock back in, since I understand there is machine work either way.


I'd rather not do a FWD swap at this time, since it would raise the compression so much, and I want to have a safe tune.

fasteddi

iTrader: (2)

I ported the snot out of my gen 1 iron heads back in the day. It helped a little N/A and when I turned it but a proper port job even if you do it yourself for free, takes 40-60 hrs of work on the iron heads and imo isn't worth the time and effort exspecially of you will be turboing.

If anything clean up the casting marks, possibly gasket match the exhaust and intake runners if needed and I would run that and spend the saved time on other aspects of the engine.

I initially ported and polished my iron heads because I tossed a cam in and wanted maximum gains. Don't get me wrong porting helps but the time for 5-10 extra hp is barly worth it. A cam swap, turbo or no, will gain you alot more. A delta 260 cam at a minimum to retain stock valvetrain, or a 270/272 delta would be much better exspecially when turboing.

Iron heads flow bad regardless. I kick myself for staying with a full iron engine for so long. Gen2 or specifically gen3 heads are a whole new world. Biggest increase of power i ever had in my 6 years of engine mods on 660s, minus a turbo or n20, was a gen 3 top end hybrid swap.

fasteddi

iTrader: (2)

Nothing wrong with keeping the iron heads. But I would leave the valves alown on the iron heads. And dependent on if you tossed a cam in, you can leave the springs alown too. Once you start constantly reving it up past 6k and or have a 270 cam or bigger you need new upgraded springs to arrest valve float and address and valve spring bind issues.

Sierra6

Thanks for the advice, though like I said, the heads are already done, and a lot of time was spent on them. Yes, I've already put a comp cam kit in with springs. 260h (yes there were better options)

Sierra6

i would be afraid of the high compression running 3500 heads with the turbo. i just paid for a new shortblock with hyper pistons (yes forged would have been better) but i want to keep it conservative.

fasteddi

iTrader: (2)

You don't need forged internals, exspecially pistons when dealing with a full gen1 V6 as long as tour tune is always good. Trust me, i push the boundaries of the stock stuff and hyper piston quite a bit and with a iron headed V6 and proper tuning which is the key, you won't have problems with hyper piston Just don't have any spark knock. Tuning is the key to a safe fast motor. Did you notice I said tuning is the key 3 times... Lol it's important. Good afrs, low timing, proper plugs, 91-93 octane gas, low intake temps.

Did you happen to check the ring gap before you put the new pistons in the block? That would be the one thing I highly suggest doing. I broke a piston ring land once because I did not do that. Stock ring gap just isnt enough for boost and exspecially hyper piston. Stock cast piston with warn rings are ok because over time They open up more because of ring wear and stock cast piston are not as fragile as hypers. Hypers will shatter like glass trust me. Although when set up right they are as strong as forged piston if not more, they are just fragile because of all the silicon. My hypers handled 450hp or more on a turbo 3.1/3100 hybrid for years.

Sierra6

the complete shortblock was assembled for me by Anderson racing. i know a spot on tune is crucial , what's worse than spark knock is pre-ignition. still, i like the buffer room.

fasteddi

iTrader: (2)

They are one in the same. detonation, spark knock, pre ignition exc..when it comes to tuning. Different events but both catrostrophic with hyper piston and boost

They built the short block with the intention of boost? That's good to hear. Alot of people just toss them in or go by factory specs and alot of the time that will cost them alot when they have a broken ring land or worse a shattered hyper piston.

Sierra6

honestly I didn't specifically tell them it was for boost, but I assume they knew I had a little something planned for it when I ordered the hypers. he did tell me that a lot of their customers run boost with no issues. they sell to a lot of fiero and chevette guys. stuff like that.

fasteddi

iTrader: (2)

Curious what size turbo you are going to use? 60-62mm? Gt3582r or something like that?

Sierra6

it's john's kit, it's sitting in my dining room . you're the one who worked with him right?

fasteddi

iTrader: (2)

haha yea I totally forgot you are the one that got it. Oops. Yea that's a ebay gt3582r. It's perfect for a iron headed v6. Won't be too hard to make a good 300 350 crank hp at 10-14psi.

Sierra6

300 crank is plenty for me, but what i'm more excited about is the gobs of torque these things seem to make when boosted.

fasteddi

iTrader: (2)

oh yea turbos are awsome at making tq. I'm sure you'll have fun. I wish I knew you were doing this a few months ago.... I litterly threw away half a turbo kit for a v6 and a few delta cams. 260 and custom 272 turbo cam, 2 whole 3400 top ends including heads..exc. it was sad to do but no one wanted the stuff. And since I've made the switch to v8, I have no need for the stuff anymore .

Sierra6

lol that's ok. i'm in no hurry to pull out the cam, and I can get the 3500 top end out the junk yard any time I want, probably cheaper than you could ship it.

Six_Shooter

iTrader: (2)

This made me cringe.

Assuming leads to broken parts.

Find out for sure what the gaps were set to.

fasteddi

iTrader: (2)

I agree with 6. I did it once and never again will I assume anything.

Sierra6

Dave has terrible hearing and an even worse memory. It was built over two years ago, I'm sure he won't remember. If it blows it blows I guess. I'll rebuild it with fwd pistons and top end if I have to tear into it again.

Sierra6

Honestly I'm not positive he gave me hyper pistons. The tops of em looked just like cast stockers to me.

fasteddi

iTrader: (2)

The top dishes will look the same. Only difference is that they will have a number stamped in the that starts with hp iirc for speed pro piston.

Sierra6

Well I might be screwed then. You guys are such heart breakers. Yours broke on the high compression alum heads right?

Sierra6

I do remember that they had arrows stamped in em for direction. Seems like I also remember numbers on em, but I remember looking at them for confirmation that they were really hypers and an HP in front of the number surely would have clued me in

Sierra6

Putting hypers in it and not boosting it wouldn't make a lot of sense would it?

Sierra6

I found the only pic I have of the tops. Def numbers stamped but I can't tell what they are

Sierra6

It looks like they say 401, which oddly enough is a forged piston according to google. I know I'm not that lucky

Sierra6

Oh. I just remembered ordered moly rings with em. Idk if that makes it better or worse or no difference

fasteddi

iTrader: (2)

Hyper pistons are generally always put in on a budget rebuild if not forged pistons it doesn't matter if it's boosted or not. My 385 V8 has hyper pistons in it. And moly coated rings are always advise for a rebuild. The HP was just for speed pro it was their part number for the pistons. You may have a different brand of piston so the number will be different entirely.

fasteddi

iTrader: (2)

I broke a piston ring land on stock compression. Iron head 3.1l I'll add I DID NOT check ring gap and always did from there on out. About 12 psi of boost. But that was 6 years ago and I wasn't very good at tuning either. So I can't rule out that detonation didnt cause it. When I broke a hyper piston it was because I was making a crap load of horse power and shot it with nitrous off the line. I made 300 400 passes at the track on the motor at that time before this happen. So it was a solid engine for years. I believe I fractured the piston. I ran a 11.23 earlier in the day at a 123 miles per hour. Later in the day the engine was just sitting idleing and bam... shattered like glass. Completely destroyed number 6 cylinder.

Sierra6

I really appreciate all the advice. There's just not a lot I can do now. I've spent so much that I've just got to run it and see what happens. I'll make sure the tuner keeps the tune on the conservative side.

drdave88

iTrader: (3)

It's better to take it apart and remeasure it now, than have to **** all that money away and spend it again to rebuild it. Not sure if you're up against the clock or something, but I'd take it back down, recheck everything you've questioned so far. That way you know it's built right the first time and it's not going to break.