Aaron's 3.4 DOHC 88GT Build Thread

Blue Shift · Post by **Blue Shift** » Thu Apr 20, 2006 11:01 pm

Aaron: I shall be forced to smite you about your head and shoulders, both in completion, and with a stock rebuild. Pwn'd in advance.

Oh, and my engine will always be more beautiful than yours = 50 Hp right there.

Aaron · Post by **Aaron** » Thu Apr 20, 2006 11:09 pm

Blue Shift wrote:Aaron: I shall be forced to smite you about your head and shoulders, both in completion, and with a stock rebuild. Pwn'd in advance.

Oh, and my engine will always be more beautiful than yours = 50 Hp right there.

I'll be down for the dyno bet!

You have a slight head start...Considering all your swap needs to be done is for you to put down the fucking welder and turn the key.

Aaron · Post by **Aaron** » Mon May 01, 2006 8:20 pm

Well I talked to the head doing my heads today, they are all but finished he is just waiting on a couple of pieces that should be there tomorrow.

He gave me a preliminary flow number, but he said he still has some minor polishing and matching to do. Full before/after sheets will come with the heads in a week or two.

The preliminary number is 328cfm at half inch lift on the intake. He said he was able to get exhaust flow increases to be about the same as the intake, but not much better. He sounded really impressed with them, he even showed interest in building a 3.4 all out, saying to let him know the next time I plan on building the lower end on one.

[Edited - Aaron, you know better than that]

The Dark Side of Will · Mon May 01, 2006 8:55 pm

I'd be very interested in reading his full comments on those heads.

I might send him a set...

Are you going to be having CHRF regrind your cams?
Flow at 0.500 really doesn't mean anything when you can only get 0.375 lift.

Aaron · Post by **Aaron** » Mon May 01, 2006 10:17 pm

Aaron wrote: I will be having a cam regrind eventually,

Mine will.

I didn't have these heads done for the lift it has now, I had them done for in the futur when I have the valvetrain, intake, and headers to turn 120hp/l and 8000rpm.

Shaun41178(2) · Post by **Shaun41178(2)** » Mon May 01, 2006 10:29 pm

Aaron wrote:. You're right about the lift, but generally flow numbers are quoted at .5", and also generally heads that improve at .5 are likely to also improve up to that point.

Wrong and wrong.

Aaron · Post by **Aaron** » Mon May 01, 2006 10:42 pm

Shaun41178(2) wrote:
Aaron wrote:. You're right about the lift, but generally flow numbers are quoted at .5", and also generally heads that improve at .5 are likely to also improve up to that point.
Wrong and wrong.

Prove it. When you quote flow numbers, it is usually at .5" lift. Now few cars actually go that high, and the numbers below matter much more, but that is the universial number.

There, I've offered 6 flowcharts directly comparing a set of heads that were improved over another. Notice gains throughout the range of lifts on both intake and exhaust.

Shaun41178(2) · Post by **Shaun41178(2)** » Mon May 01, 2006 11:07 pm

No .5 is wrong. If you notice all yours go to .7. When I had my al heads flowed they asked me how big my cam was. I told them, so they went no higher then the cam lift. Whats the point of going higher then the cam lift that you will be using?

You better not be confusing .5 with 28 in of Hg because if you are I am going to break my foot off in your ass. Thats a recognized standard for flowing heads but isn't followed by all head shops. Its sort of a understanding between flow testers to use 28" so everything is based off the same vacuum readings.

It is also very possible to hurt low end flow but increase higher lift flows. Nto everyone is a pro and lots of people fuck up. You think those charts will ever get posted on the internet? Esp by a reputable shop trying to sell a product?

MNFatz · Post by **MNFatz** » Mon May 01, 2006 11:10 pm

Aaron · Post by **Aaron** » Mon May 01, 2006 11:42 pm

Shaun41178(2) wrote:No .5 is wrong. If you notice all yours go to .7. When I had my al heads flowed they asked me how big my cam was. I told them, so they went no higher then the cam lift. Whats the point of going higher then the cam lift that you will be using?

Mind finding me a cam that goes to .7" lift? Point is, the heads I just hsowed gain over a professional Brodix head from .1" to .7". You won't find a camshaft that likes the other heads more.

You better not be confusing .5 with 28 in of Hg because if you are I am going to break my foot off in your ass. Thats a recognized standard for flowing heads but isn't followed by all head shops. Its sort of a understanding between flow testers to use 28" so everything is based off the same vacuum readings.

Yes my heads were done at 28 in mercury...And when you are given a single flow number, most if not all places will quote it at either .4 or .5" lift, because that is the highest flow that most built motors will take advantage of.

It is also very possible to hurt low end flow but increase higher lift flows. Nto everyone is a pro and lots of people fuck up. You think those charts will ever get posted on the internet? Esp by a reputable shop trying to sell a product?

Well the shop that did my heads is pro. And I'll have the flow charts, and I'll bet you money they'll flow more from low lift to lifts I could never use.

Shaun41178(2) · Post by **Shaun41178(2)** » Mon May 01, 2006 11:54 pm

Aaron wrote:
Mind finding me a cam that goes to .7" lift?

Mind finding me a 3.4 dohc cam that goes to .5 lift?

The Dark Side of Will · Tue May 02, 2006 9:16 am

BOTH OF YOU...

Heads are flowed at 28 inches of WATER, not mercury. 29.92 inches of mercury is standard atmospheric pressure. That same pressure is approximately 30 feet of water. When you quote pressure using inches of the wrong substance, you'll be off by a factor of the specific gravity of mercury.

Most of the flow quotes I've seen have been at the .400 to .500 range. That's because shops want to publish the biggest numbers they can. However, those lift numbers are not even close to being as standardized as 28 inches of water.

Big block Chevy cams can hit 0.700 at the valve with the right rocker ratio.

Be careful how much lift you get on a regrind. Allen Cline and Alan Johnson figured out how much lift a N* could take without having valvetrain issues and came up with 0.450. The limitation was off center force on the valve lifter.

Since the 3.4 has the same diameter lifters as the Northstar, I would expect it to have similar valve lift limitations.

What do ARAO heads have to do with anything in this thread?

Aaron · Post by **Aaron** » Tue May 02, 2006 10:35 am

The Dark Side of Will wrote: Most of the flow quotes I've seen have been at the .400 to .500 range. That's because shops want to publish the biggest numbers they can.

That's what I'm saying, and generall,y if the guy doing the work knows what he is doing, a gain at .5 of 60 cfm is very likely to gain at any lift.

Be careful how much lift you get on a regrind. Allen Cline and Alan Johnson figured out how much lift a N* could take without having valvetrain issues and came up with 0.450. The limitation was off center force on the valve lifter.

I've never heard that, but even so, .450 would be AMAZING on this motor...I mean the HO Quads only run like 411 right?

What do ARAO heads have to do with anything in this thread?

It was to show princess shauney that a good set of heads will gain significant flow throughout the lift range, and I expect mine to do the same.

Kohburn · Post by **Kohburn** » Tue May 02, 2006 10:53 am

plan this - expect that -

less talking - more doing

if you don't say what you expect to or plan to get then shaun can't argue with you about it - then you can just post what you ACTUALLY GET and that'll be the end of it

The Dark Side of Will · Tue May 02, 2006 11:01 am

Aaron wrote:
The Dark Side of Will wrote: Most of the flow quotes I've seen have been at the .400 to .500 range. That's because shops want to publish the biggest numbers they can.
That's what I'm saying, and generall,y if the guy doing the work knows what he is doing, a gain at .5 of 60 cfm is very likely to gain at any lift.

You left out an important part of the quote:

The Dark Side of Will wrote:However, those lift numbers are not even close to being as standardized as 28 inches of water.

And even 28 inches of water isn't officially standardized anywhere.

Aaron wrote:
DSW wrote: What do ARAO heads have to do with anything in this thread?
It was to show princess shauney that a good set of heads will gain significant flow throughout the lift range, and I expect mine to do the same.

I don't think it shows that. To show what you're trying to show, you'd need flow information before porting and after porting. Comparing different heads doesn't do it.

Shaun41178(2) · Post by **Shaun41178(2)** » Tue May 02, 2006 1:26 pm

Aaron why must you always act like a retard and totally miss my point? All I was saying is that just because there is an improvement at .5 that doesnt' mean there is an improvement at .1 or .2. And untill you get your flow results you dont' know either.

Still waiting for the dohc cam with .5 lift info. I mean shit if you are going to flow your dohc heads with .5 lift, might as well pull both fucking valves out to show huge increases of flow. WOW awesome port job!

FYI I have a roller cam that has .630ish lift on the intake side and its not even the biggest cam. SO there are cams out there with .7 lift. I dont' care to go looking for them though because frankly I dont' feel like wasting my time to prove you wrong when I already know you are.

And yes Will I know its water but dont' know why I typed hg. And yes 28" isn't standardized like I said before. Its just what a lot of shops use.

Aaron · Post by **Aaron** » Tue May 02, 2006 1:43 pm

Shaun41178(2) wrote:I dont' feel like wasting my time to prove you wrong when I already know you are.

So you know that my heads won't gain under .5"?

Mach10 · Post by **Mach10** » Tue May 02, 2006 1:52 pm

When has any 4-valve head gained at more than .5" lift...

The DOHC valves are about as big as they can be without scraping the sides of the cylinder. How do you NOT get shrouding problems at high-lift?

This is a legit question... CAN you make these kinds of 4-valve heads behave properly at that kind of lift? :scratch:

Fastback86 · Post by **Fastback86** » Tue May 02, 2006 4:57 pm

I think the more pertinant question is why, when you have 4 valve heads, do you need such huge lift? If it were a 2v motor, ok I see it. But if you've already got 2 more valves, you're already ahead of the game. The same amount of lift on a 2v and 4v motor is going to produce drastically different amounts of flow, while the displacement (say if we're talking 3.4 OHV vs DOHC) hasn't changed.

Aaron · Post by **Aaron** » Tue May 02, 2006 5:01 pm

Well of course I don't "need" it. But if I have the intake manifold to take advanatge of it, why not?

My point here isn't to just beat a built 3.4 OHV, I could do that without even trying. The point here is to go past that, making the power of much higher displacement engines.