My new TA SI Heads and GN1 Aluminum Heads

[X Ray]

This is not meant to be a good vs bad comparison between TA Performance SI heads and GN1 Aluminum heads. This is simply an “Out of the Box” look at what your money buys. It should be noted that both sets of heads were purchased un-ported.

The new GN1 heads were at Dave’s shop for another engine build when we started the clean-up work on my TA SI heads. When I say we, I mean Dave. During my work on the TA heads, I documented some visual differences between the two different cylinder heads.

Visually, the TA heads appear to have the pushrod holes machined to tighter tolerances and have slighted larger intake valves. The GN1 head as received have a much smaller lip (almost none) in the valve bowl area under the valve seat. The TA heads have a significant lip in the valve bowl area under the valve seat. My goal on this project was to eliminate this lip on the TA head and improve the airflow

Another difference noticed which may or may not be significant was a difference in the combustion chamber finish. The TA SI heads have an “As Cast” finish. The GN1 heads have a fully CNC’d combustion chamber. You will see this and other differences on the attached slides.

I am very pleased how the TA heads turned out and I plan on putting them on the car in August.

 

[bison]

Huge gains cleaning up those ex bowls on the TA's. About 40cfm with 5 minutes of work!


Sent from my iPhone using Tapatalk

 

[TURBOELKY]

Nice. I'm a little shocked at the TA heads. Champion look great out of the box. I would love to test both heads on a bench before and after port work. That lip would be a disaster to performance if left as is!

 

[Mike T]

Surprised that the TA's didn't at least have a little blending done under the seats.

 

[Chuck Leeper]

Maybe weigh them?

 

[X Ray]

Maybe weigh them?

I did not weigh them but I did pick both up after the work was performed.... and the TA are heavier.

 

[Steve V]

What kind of seat pressures on the springs that came with tas?

 

[X Ray]

What kind of seat pressures on the springs that came with tas?

You order the springs you want on them.

 

[Ttype6]

The most amazing thing,that I've noticed,is that you were able to get a set of Champions at all. Which set of heads are the best? The ones that you can get. They're both fine products.

 

[Chuck Leeper]

I did not weigh them but I did pick both up after the work was performed.... and the TA are heavier.

Less mass in critical locations = cracks, deck integrity compromised.
Know for a fact, the Champs are/were cast by a co that has/had made recs that the molds be modified. Ever done? Don't know.
The sets that I had, {3}, all had issues. Cracks, deck flex, seats, guides falling out.
The "suggested" cause: Overloading the bolt columns w/ excessive torque on the studs.

 

[ek02]

"The "suggested" cause: Overloading the bolt columns w/ excessive torque on the studs."

Kind of sounds like the excuse I got when a Chinese rocker stud broke after 3 months. "You over tightened the lock nut". I put ARP Chevy rocker studs in 6 years ago, no problems yet.

 

[Chuck Leeper]

"The "suggested" cause: Overloading the bolt columns w/ excessive torque on the studs."

Kind of sounds like the excuse I got when a Chinese rocker stud broke after 3 months. "You over tightened the lock nut". I put ARP Chevy rocker studs in 6 years ago, no problems yet.

The Ho Chi Min rockers were junk, too. They lasted about 1 dyno pull. Threw them in the trash, got a set of T&D's... No more issues.
The first set of heads I had cracked before I put the first boost to them....Only took 17 weeks to get them back. Only then, after they were "found" under the repair shop bench.

 

[Mr.Spool]

Threw them in the trash, got a set of T&D's... No more issues.

yup never hurt a td yet

 

[turbobuick]

Champions are junk and Tom is a Liar I cant believe anyone still deals with them.

 

[Ttype6]

Champions are junk and Tom is a Liar I cant believe anyone still deals with them.

I would pity anyone who would try to prosecute you for libel for this statement.

 

[turbodave231]

would pity anyone who would try to prosecute you for libel for this statement.

The truth will set you free!!

This was a fun project!! It was nice to compare two products side by side. We took some serious weight off the TA's with this process.........and it took more than 5 minutes Brian!!!! I bet we spent an hour or more on each head.

But I'm sure Rick's results will be well worth our effort.

This is the first set of TA's I've looked at and re-worked. So far, I am impressed. I would buy them un-assembled with the valve job done to make the rework faster. I can see even more opportunity to obtain more flow out of the TA heads, but I'd want to verify all changes on a flowbench.

My feedback on the TA's:

• Overall a Very Nice product
• Valve bowls should be pocket ported out of the box (nobody would want to use them as shipped)
• Combustion chamber should be CNC machined out of the box
• Lot of potential for more flow
• Overall cost is more than the GN1's
• A specific set of rocker arms is available that avoid the pushrod interference problems inherent with the GN1's
• Better Availability than the other alternative

 

[Nick Micale]

The truth will set you free!!.................................................

A specific set of rocker arms is available that avoid the pushrod interference problems inherent with the GN1

Dave, the pushrod holes in the TA SI heads are positioned to enable the use of stock rockers.

Not many owners use stock rockers, and TA does sell a set of T&D rockers specific to fit the SI heads.

 

[Ttype6]

TA does sell a set of T&D rockers specific to fit the SI heads.

This is what he was saying in the sentence you quoted.

 

[joeynj]

The Ho Chi Min rockers were junk, too. They lasted about 1 dyno pull. Threw them in the trash, got a set of T&D's... No more issues.
The first set of heads I had cracked before I put the first boost to them....Only took 17 weeks to get them back. Only then, after they were "found" under the repair shop bench.

Ho Chi Minh is Vietnam not china my friend.

 

[joeynj]

The Ho Chi Min rockers were junk, too. They lasted about 1 dyno pull. Threw them in the trash, got a set of T&D's... No more issues.
The first set of heads I had cracked before I put the first boost to them....Only took 17 weeks to get them back. Only then, after they were "found" under the repair shop bench.

Ho Chi Minh is Vietnam not china my friend.