Ported vs non ported GN1's

[Ed Valvo]

Debating with a guy at work... What increase in HP levels can be expected from a set of cast GN1's vs ported GN1's? Assuming the block holds together.

 

[TNTSNBS]

50 to 60 rwhp max depending on your combo.

 

[Nick Micale]

Based upon the engines we have done, a max port job on a set of GN-1 heads would double the HP from an out-of-the-box set.

HP is all about airflow, and max ported GN-1's have gone into the 8's.

 

[jasjamz]

I see you guys are saying Max ported. Is this meaning a set from a experienced head Porter. How about a set with the porting done from Champion vs the as cast set from Champion

 

[Scott87]

Subscribed.

 

[tonysmach]

Based upon the engines we have done, a max port job on a set of GN-1 heads would double the HP from an out-of-the-box set.

HP is all about airflow, and max ported GN-1's have gone into the 8's.

Nick, can you give an example when you say double HP. Are you saying that if my current build is pushing 600 WHP it can go to 1200 WHP. My off-the-shelf GN1 heads are on there way from Champion....so should I get them ported? My build will be a 249 CID with forged internals, DLS cam, etc.

 

[pdzz]

Nick, can you give an example when you say double HP. Are you saying that if my current build is pushing 600 WHP it can go to 1200 WHP. My off-the-shelf GN1 heads are on there way from Champion....so should I get them ported? My build will be a 249 CID with forged internals, DLS cam, etc.

I think what Nick is saying.. If you gain 40 horse out of box, you can get 80 with port work. Nick, please correct me if I'm wrong. Depending on other factors ie. cam, turbo, etc. You might get more. My two cents. Phil.

 

[TurboTnZ06]

I believe I have out of the box GN1 porting (studded individual adjustable roller rockers though with big valves), and the port matching is almost perfect on a stock ported lower intake. Also, the stock headers are smaller than the exhaust head ports on the unported GN1's. I would say if you have GN1's also get bigger headers since that is the next bottleneck that I'm seeing, if going max performance. I blew a header gasket (I forgot to tighten the nuts) the other week and noticed the size difference on my stock headers on the GN1's around the gasket imprints, it was a couple 16ths, almost an 1/8th of material easily I was giving up by using stock headers.

 

[tonysmach]

I think what Nick is saying.. If you gain 40 horse out of box, you can get 80 with port work. Nick, please correct me if I'm wrong. Depending on other factors ie. cam, turbo, etc. You might get more. My two cents. Phil.

That makes sense. I have also read on here that more flow in the heads does not always equate to more HP.

 

[Ed Valvo]

Also, the stock headers are smaller than the exhaust head ports on the unported GN1's. I would say if you have GN1's also get bigger headers since that is the next bottleneck that I'm seeing, if going max performance. I blew a header gasket (I forgot to tighten the nuts) the other week and noticed the size difference on my stock headers on the GN1's around the gasket imprints, it was a couple 16ths, almost an 1/8th of material easily I was giving up by using stock headers.

Good point. I'm assuming the ports are larger on after market headers. Anyone measure the difference of a stock header vs after market?

 

[Ed Valvo]

I think what Nick is saying.. If you gain 40 horse out of box, you can get 80 with port work. Nick, please correct me if I'm wrong. Depending on other factors ie. cam, turbo, etc. You might get more. My two cents. Phil.

I also believe this is what Nick meant to say. I'm surprised porting aluminum heads makes that much of a difference. Considering how much heads cost, HP per dollar, to me it makes sense on a race engine. I'm sure the quality of the port work must be top notch as well. Not just some Ricky Rooter job. (Old Terry Ryan saying)

 

[Nick Micale]

That makes sense. I have also read on here that more flow in the heads does not always equate to more HP.

Back in the "dark ages" when I was in school studying engine design, one fact has always stuck in my memory, and it is "air and fuel are needed to make HP". So it follows, more air/fuel makes more HP!

Granted, like Phil mentioned, many other items also affect power output. However, any way you call it, more air/fuel in, and more air/fuel out is the manner in which you increase HP.

A larger turbo will do that, but remember boost is restriction, so larger ports lessen restriction so the turbo works better.

Another important factor is combination of parts that work together for a specified performance goal. You can have heads, or a turbo, that are too large for the job at hand and do not meet the performance goals.

In that case, Tony's comment above would be true, but they have a screwed up combination.

 

[vacuum 6]

What no one going to talk about engine RPMs?

 

[V6RACER]

Everything being equal (engine,cam,intake,turbo,rpms,springs,etc) Non ported GN1 went best of 9.38 at 28 psi, swapped to Champion ported GN1s and went same et with 4 psi less boost.

Like Nick said, boost is a restriction.

 

[Pittsburghkid]

http://www.turbobuick.com/forums/engine-tech/216319-gn1-rs-ported-unported-stock-heads.html

 

[bison]

They could be worth nothing or 125hp. More rpm potential if the rest of the combo is there. You should make about 700whp around 25psi with a solid tune on those heads on a 9:1 stock stroke 3.8 engine.

 

[Ed Valvo]

Anyone have flow numbers for ported aluminum GN1's (By champion) vs cast aluminum GN1's?

 

[BEATAV8]

Anyone have flow numbers for ported aluminum GN1's (By champion) vs cast aluminum GN1's?

This data isn't quite what you're looking for but it's something... This was a $350 or $400 porting job if I remember correctly. 10% increase with some pretty minor basic stuff.

Some Flow Data
I had some work done on my GN1's.
Tested @ 28"
AS-CAST GN1 INTAKE
LIFT CFM
.100 61.7
.200 119.8
.250 146.2
.300 170.6
.350 189.9
.400 202.7
.450 211.1
.500 211.2
.550 213.4

AS-CAST GN1 Exhaust
LIFT CFM
.100 56.2
.200 108.4
.250 125.7
.300 140.8
.350 151.7
.400 159.3
.450 165
.500 168.9
.550 171.6

The intakes were then gasket matched to FelPro 1200
Bowls were blended on the intake and exhaust
Exhaust was cleaned and polished throughout it's length
It's a Basic "econo port" from Precision Engine and Machine (local shop)
EconoPort GN1 Intake
LIFT CFM
.100 63
.200 121.8
.250 150
.300 177
.350 201.5
.400 219.9
.450 230.5
.500 236
.550 230.4

EconoPort GN1 Exhaust
LIFT CFM
.100 56.2
.200 110.3
.250 127.5
.300 144.1
.350 158
.400 169.3
.450 178.3
.500 187.2
.550 192.6

 

[turbofabricator]

Flow quality is more important than quantity. Years ago I had a buddy that went from Dart Buick (chevy V8) heads to Brodix heads that flowed more air (20+ cfm) and the car slowed down. He had sold the Buick heads and intake and couldn't go back. He claimed the air made it into the cylinder more to the center of the bore than the Brodix heads did. There is an article in Hot Rod mag this month about LS(X) heads and how they performed. Some of the heads that flowed lower than others made more power than the ones that flowed more. No one races a flow bench. Though many many folks get taken by someones advertised flow numbers. But I will add that everything has to match. Just step up flow and not camshaft and RPM, and you go slower. As Nick stated, engines are an air pump. You either get more air into a cylinder or you turn it at a higher RPM to make more HP. HP is measured as pounds of air per minute (with the correct amount of fuel thrown into the equasion) Either push more air into the cylinder (boost) or spin it at a hight RPM. Simple math actually. If you run a TA-49 turbo and remove your un ported GN1 heads and swap with ported GN1 heads, it'll net you nothing. Now, change cam, and turbo and spin the crap outta it, it WILL make more power. You will only gain more power IF the heads are maxed out to begin with. This is an over simplification to say the least. The older I get and the more I learn, the dumber I feel.