Gn1 heads any good???

[007gn]

My question is : are the old casting gn1 8 bolt shaft mount aluminum heads any good / worth using on my 4.1 . I would be pushing them at boost levels of 25-33 psi . With 93 n alky. I'm having the heads checked for cracks n leaks first. But even if they do check out to be in good working order I want to know the pros & cons to using these heads. I don't want to use anything that may come back to haunt me . Thanks guys.

 

[TT/Ameasap]

If they check out fine, then your probably good. Running aluminum heads is no different than iron as far as reliability or tolerance levels.

 

[drturbo69]

do a search gn1 cracking

 

[Chuck Leeper]

Mine cracked B4 the first dyno pull...
If you want a set of alums, get a set of T/A's.

 

[whitehot1]

I bought my Champion GN1 aluminum 8 bolt heads in 2001 from ATR when they were in business. I use the T&D shaft mounted roller rocker arms on them.
They work great for me.

So i guess not all of them were made bad.

 

[GNVenom]

I had a set of GN1's in 1999, and had major problems with one or both of them. Porosity was the explanation, but the effect was coolant in the oil. After changing upper gaskets four times, I finally SCRAPPED the heads, took a major loss. My bearings and turbo took a hit with the glycol in the oil as well, so it was a costly problem.

At the time, customer service was non-existent. Champion would not fess up to the problem (a replacement set would have been the response).

No more champs for me. Learned a valuable lesson.

 

[MCH86GN]

How about present day GN1 heads?

 

[Eticket]

The newer the casting, the better. the oldest ones have the champion gn1 logo on the side between two of the exhaust ports. These early ones had the mfg issues as well as most of the cracking.

The newer ones without this big logo on the side have seemed to be better. I have some early/mid 2000's versions on my current car with absolutely zero issues. Also guys use of the cometic gaskets over the past 7-8 years have helped vs. wirelock, coppers, etc etc... So be sure you plan for that with the deck machining needed. Can't blame that on heads themselves.

 

[MCH86GN]

The newer the casting, the better. the oldest ones have the champion gn1 logo on the side between two of the exhaust ports. These early ones had the mfg issues as well as most of the cracking.

The newer ones without this big logo on the side have seemed to be better. I have some early/mid 2000's versions on my current car with absolutely zero issues. Also guys use of the cometic gaskets over the past 7-8 years have helped vs. wirelock, coppers, etc etc... So be sure you plan for that with the deck machining needed. Can't blame that on heads themselves.

My engine builder, Dave Roland, gave the GN1s a thumbs up. Just got a brand new set. Dave is a certified machinist and an experienced v6 engine builder and other performance engines. He will use Cometic, I'm certain. He is one of the most upstanding and honest people I have ever dealt with.

 

[TT/Ameasap]

It would be better if he were a metallurgist.

 

[Chuck Leeper]

Try a search... recent thread on this topic....

 

[Eticket]

The OP asked about the older GN1's. I'd say if you know the history on them, then you're probably ok, but if you don't - only consier them if they are in the best of shape and have been run hopefully to get the bugs out.

 

[vacuum 6]

I had a set of GN1's in 1999, and had major problems with one or both of them. Porosity was the explanation, but the effect was coolant in the oil. After changing upper gaskets four times, I finally SCRAPPED the heads, took a major loss. My bearings and turbo took a hit with the glycol in the oil as well, so it was a costly problem.

At the time, customer service was non-existent. Champion would not fess up to the problem (a replacement set would have been the response).

No more champs for me. Learned a valuable lesson.

With leakage that bad I would assume the porosity was visible?

 

[750H.P.V6]

The early Champion heads were much lighter duty castings and had some machining issues both of which led to cracking problems. The later castings are much more substantial and thereby more durable. If you're looking for a used set, the later ones can be identified by the logo being relocated to the end of the head.

Neal

 

[turbodave231]

I don't need a degree in metallurgy to figure out casting problems. The early GN1s had a couple of issues. If you have been around in the Buick world you already know that. The first batch of TA blocks had issues too. No suprise really. We (the customers) are the research and development team.

I have used several sets of the latest GN1 castings without any issues.
We made over 620 RWHP (tuned by Cal) on an unported set using Alky and pump gas.

Cracking issues aside, I would personally stay away from buying used heads. They probably need refreshing and that plus the used price usually gets close to the price of a new set.

 

[Nick Micale]

... The first batch of TA blocks had issues too. No suprise really. .........

Dave, I respect what you know and do, but the issues with the first TA alum blocks were due to the engine builder's lack of experience and knowledge in building an alum block.

My build was the first TA block produced, and with over 1000 passes there never has been any issue with my block as well as NONE of the ones we have built.

The problem with the Champion heads cracking was due to too not enough strength around the combustion chamber and lots of boost and HP, just ask Cal when he split his Champion head and ended up inches from the wall at the end of a 150+ MPH pass due to water blowing out on the track, and that was not his first one to crack.

 

[007gn]

The early Champion heads were much lighter duty castings and had some machining issues both of which led to cracking problems. The later castings are much more substantial and thereby more durable. If you're looking for a used set, the later ones can be identified by the logo being relocated to the end of the head.

Neal

Thanks for that helpful information now I know how to identify some of the newer casting heads

 

[turbo nasty]

TA heads get my vote. GN1's have had too many issues for me. Even the later castings still had issues with smoking due to poor valve guides.

 

[MCH86GN]

TA heads get my vote. GN1's have had too many issues for me. Even the later castings still had issues with smoking due to poor valve guides.

I'm going GN1, hopefully I can report back on this thread every summer for the next 5 years.

 

[forcefed3.8's]

I have been running gn1s since 2009. The first set was one of the very first made. I ran into the 9s with them, other than the exhaust guides breaking, i had no issues. The set I have now have been on the car since 2010 and they are the latest casting. No issues running 8s.