Group A Head

[gofastgeorge]

:biglaugh: LoL, a dam to prevent port reversion, in a turbo engine, now that funny as hell !!

Let's see, intake charge at say a mild 10 psi........
Exhaust back preasure at about 5 psi (if that)

Just what will cause 5 psi exhaust gas to flow back into an open exhaust valve at the last milisecond while the intake valve is already starting to open with 10 psi pushing the next charge in ?

Oh, I know......
The Force Luke, the Force !!

That theory only applies to a NA engine, and usually only some pig-iron V8.
And even people who build those have left it on the shelves, gathering dust........

 

[Poodles]

:3d_frown:

 

[89nasupra]

In theory yes the exhaust dam effect could be restored but the amount of overlap would need to be correctly sized and there is a possibility it would affect the torque output and curve depending on what was done to the ports. For every action there is a reaction and its still true here[/QUOTE]
posted by GC89

ok, but it would have to improve performance if under more boost and bigger cams it would have to help to have bigger exhaust ports just still with the reverse daming method going for the proper flow effect.

 

[Davegt27]

Looks like that Group A head is gone

hey what are the rules for Group A, I know it was a racing class in Japan but it would be nice to have a little more info

I would assume that TRD Japan would know what they where doing and would not go to all that trouble to turn out some junk head

any info would be help full

Davegt27

 

[GC89]

:biglaugh: LoL, a dam to prevent port reversion, in a turbo engine, now that funny as hell !!

Let's see, intake charge at say a mild 10 psi........
Exhaust back preasure at about 5 psi (if that)

Just what will cause 5 psi exhaust gas to flow back into an open exhaust valve at the last milisecond while the intake valve is already starting to open with 10 psi pushing the next charge in ?

Oh, I know......
The Force Luke, the Force !!

That theory only applies to a NA engine, and usually only some pig-iron V8.
And even people who build those have left it on the shelves, gathering dust........

The key here is we are talking about a STREET CAR I dont know about you but Im not boosting 24 hours a day. Off boost a turbo engine will behave THE SAME as a naturally aspirated engine so the concepts are still relavent.

 

[gofastgeorge]

The key here is we are talking about a STREET CAR I dont know about you but Im not boosting 24 hours a day. Off boost a turbo engine will behave THE SAME as a naturally aspirated engine so the concepts are still relavent.

Well, if your stuck with one car, and are more concerned with mileage, and low speed running than performance,
then you should leave it stock, and not mess with it at all.

I have an old truck for commutes, and grocery runs. (more to gaurd against stupid-ass drivers talking on their cells killing my car)
The 7M I drive when I want to go kick mustang ass.
And the funny thing is, with all the low speed crap deleted from mine, like the ICS, most, but not all of the crap in the combustion chamber,
AND 4.56 gears, it will still knock down 22 mpg on the highway.....

Damn, I wish I had money for that real nice one in Canada.....

 

[IJ.]

The key here is we are talking about a STREET CAR I dont know about you but Im not boosting 24 hours a day. Off boost a turbo engine will behave THE SAME as a naturally aspirated engine so the concepts are still relavent.

And there's an important distinction, I build fast road cars (hence my post in the Cam's thread) NOT race cars with number plates.

I try to make improvements across the board so the car can be driven daily and never misbehave no matter what I do with it, last 7m was making 500+rwhp and still pulling down 28 Us Mpg on the highway.

 

[87M-GTE]

Looks like that Group A head is gone

hey what are the rules for Group A, I know it was a racing class in Japan but it would be nice to have a little more info

I would assume that TRD Japan would know what they where doing and would not go to all that trouble to turn out some junk head

any info would be help full

Davegt27

The Head was no where near stock specs. It consisted of upgraded cams, Larger Ti Valves, Re-shaped combustion chamber and Porting/Polishing, probably more.

A Group A car had to be based off of a production car ie: Turbo A Supra, E30 M3, Skyline GT-R32, etc.
Those companies involved in the Group A races had to produce at least 500 cars for the public to qualify for a Group A car.
As far as motor/drivetrain modifications go, As far as I know they were unlimited. More info can be found on this link.
http://www.turbosupras.com/pages/pages/specifications/MA70GA/ma70ga.htm

 

[Davegt27]

Very cool

Even the Air jack system is cool
I bet if one followed some of the stuff done on that car there car would kick butt

Davegt27

 

[manzai]

Yeah, and imagine if we could delete our fans and run our intercooling pipes in that fashion!

 

[HKS_TRD]

And this one is a little different again, looks deeper?
(might just be camera angle though)

That one there is my Brothers head and its the real deal, as he bought a complete Group A motor, so I inherited the oil pan he had previously bought

The motor is coming apart again later this year so we will try and get alot more pics of the head

More info can be found on this link.
http://www.turbosupras.com/pages/pages/specifications/MA70GA/ma70ga.htm

I wrote that article, I forgot all about it till you put the link up !

 

[92nsx]

^^^ First time I have seen that site. Great write up