Who is running GN1 Heads on a daily driver?

Amelio said:
Thats huge! a ton less stress for roughly the same e.t that is a fantastic improvement.
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The old combo at 17-18 psi only ran 11.8-12.0 at 113-115.

My GN1 exhaust ports are bigger than the stock header openings, so I'm probably leaving something on the table there for header flow.

I went to at least 35-40 over DLS stroker (my block was already 33 over from before), ported the lower stock intake, 70mm throttle body, 3 inch uppipe, wideband correction, 4 inch intake, but everything else related to air flow is the same. Spoolup is instantaneous on a 10 yr old journal turbo now. 0-25psi in .8 seconds leaving off the footbrake and bleeder style external wastegate control according to the log.
 
TurboTnZ06 said:
The old combo at 17-18 psi only ran 11.8-12.0 at 113-115.

My GN1 exhaust ports are bigger than the stock header openings, so I'm probably leaving something on the table there for header flow.

I went to at least 35-40 over DLS stroker (my block was already 33 over from before), ported the lower stock intake, 70mm throttle body, 3 inch uppipe, wideband correction, 4 inch intake, but everything else related to air flow is the same. Spoolup is instantaneous on a 10 yr old journal turbo now. 0-25psi in .8 seconds leaving off the footbrake and bleeder style external wastegate control according to the log.
Click to expand...

the 11.8-12.0 on your old combo...was that on pump gas and alky? the reason I ask is because my can has run a 12.0 @ 115 on 17-18psi.....I am going to the track tomorrow I have installed a new much better working converter....I hope to get into the 11's on 18-psi or less all on pump gas.

I have thought about going to GN1 heads but I don't really see the need to spend that kind of money especially since I am running lower boost levels.
 
Not for nothing, but if this car is really going to be a daily driver I would leave it as close to stock as possible.
 
Amelio said:
the 11.8-12.0 on your old combo...was that on pump gas and alky? the reason I ask is because my can has run a 12.0 @ 115 on 17-18psi.....I am going to the track tomorrow I have installed a new much better working converter....I hope to get into the 11's on 18-psi or less all on pump gas.

I have thought about going to GN1 heads but I don't really see the need to spend that kind of money especially since I am running lower boost levels.
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My 11.8-12.0 combo was on 104 I think, it was back in 2002.
 
ok cool well I mix 93 and E-85 and I am able to run 17psi on that I will find out what that relates to in an e.t tomorrow......also gonna find out how much timing I can run with that fuel combo.....currently running 20degrees on the street with no issues.
 
Our boost reading is a measurement of the pressure in the intake manifold. We are measuring the pressure of the air that hasn't entered the motor. If we leave everything the same except adding heads with larger ports and larger valves,we have removed some restriction that results in more air entering the cylinder at any given compressor speed. If we spin the turbo at the same rpm after upgrading the heads,it is still moving the same amount of air,but more is able to get into the cylinders which results in lower pressure in the intake manifold. Because the turbo's work load is less,the back pressure in the exhaust is lower which allows more of the exhaust gasses to leave the cylinder during the exhaust stroke which results in a better,denser,fresher,cooler charge of air entering the cylinder during the next intake stroke. Aluminum heads don't make more power,but they do allow our motors to make more power because the cooling effects of the aluminum allow us to increase compression,boost,and spark advance.
 
Ttype6 said:
Our boost reading is a measurement of the pressure in the intake manifold. We are measuring the pressure of the air that hasn't entered the motor. If we leave everything the same except adding heads with larger ports and larger valves,we have removed some restriction that results in more air entering the cylinder at any given compressor speed. If we spin the turbo at the same rpm after upgrading the heads,it is still moving the same amount of air,but more is able to get into the cylinders which results in lower pressure in the intake manifold. Because the turbo's work load is less,the back pressure in the exhaust is lower which allows more of the exhaust gasses to leave the cylinder during the exhaust stroke which results in a better,denser,fresher,cooler charge of air entering the cylinder during the next intake stroke. Aluminum heads don't make more power,but they do allow our motors to make more power because the cooling effects of the aluminum allow us to increase compression,boost,and spark advance.
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I disagree on the spark advance with the aluminum heads. They don't need a lot of advance. Also the mass flow potential of the engine is greatly increased at higher rpm with the higher flowing head. Cam/valvetrain the engine and give it enough turbo and it's easy to see where the advantage is. The user determines the advantage the heads may give.
 
bison said:
I disagree on the spark advance with the aluminum heads. They don't need a lot of advance. Also the mass flow potential of the engine is greatly increased at higher rpm with the higher flowing head. Cam/valvetrain the engine and give it enough turbo and it's easy to see where the advantage is. The user determines the advantage the heads may give.
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Bison......if I am getting what you are saying in this post and an earlier one....with everything remaining the same with the exception of a head swap a large improvement would not really be seen until higher boost levels where more mass flow is introduced...correct?

For example if all I did to my car was a head swap then I would not recessionary see a big difference from an 18psi run from the irons to the aluminum's but would see it in a higher level such as 25psi or better....correct?
 
Amelio said:
if all I did to my car was a head swap then I would not recessionary see a big difference from an 18psi run from the irons to the aluminum's but would see it in a higher level such as 25psi or better....correct?
Click to expand...
You might not see any gain. It would allow you to run more boost at any given octane level. Again,the gains come from what the heads allow you to do.
 
Amelio said:
Bison......if I am getting what you are saying in this post and an earlier one....with everything remaining the same with the exception of a head swap a large improvement would not really be seen until higher boost levels where more mass flow is introduced...correct?

For example if all I did to my car was a head swap then I would not recessionary see a big difference from an 18psi run from the irons to the aluminum's but would see it in a higher level such as 25psi or better....correct?
Click to expand...
Actually I'm saying that the heads will allow a larger cam to increase the mass flow a crap load if the turbo/intercooler isn't a restriction. My black car traps on 93/alky 138+ in average air at LVD @ 24-25psi, 21-Its an 8.95:1 stock stroke with a custom hyd roller. It has GN1 heads with a lot of work done to them. With boost as low as 17-18psi and timing in the 19-20* range it made over 520whp. Not a problem on 93 octane. If I changed the cam and converter (loosen it) on that combo to raise the rpm a few hundred it would take even greater advantage of the heads abilities to increase mass efficiency at higher rpm. Let say we were getting a mass efficiency of 88% at 5500 making 525whp@17psi then we change cams, and converter and now we are at 5800 and still getting an 88% mass efficiency. Probably around 570whp. The result is a big increase in mass flow which equals a lot of power. Notice we haven't increased cylinder pressure at all. We are simply revving faster while achieving the same cylinder fill. Octane requirement will be very close on the two examples. There are many other factors to consider but that is the general outcome if the engine revs higher while achieving the same cylinder fill.
 
I can give a little comparison on steel heads vs aluminum. My TType has steel heads and my dads GN has aluminum.
Both motors are stroked and run 9 to 1 CRs. Cubic inch displacement is pretty close too. Both have FAST units in them and they both run pump gas and alky.

The aluminum heads allow for more timing than the steel heads do. So yes the aluminum heads are less sensitive to detonation than the steel heads.

Would I go switch to aluminum heads on a daily driver ? No it's not worth it. You can put that money to good use in other places.

Hope that helps.
 
Here's my comparison with the passes being made in my black car @3550-3600lbs. Both had xfi, 9.5"ptc, g body front mount, and 6680 turbo. Decent iron heads on 8.3:1 stock shortblock with slow 212/212 cam equals 10.29@133.4mph with 29-30psi/23*advance. Gn1 heads ported by Russ Merritt on stock shortblock with fast ramp 212/212 equals 10.13@135.6mph with 26psi/22*. I was out of turbo in both cases and had the wastegate pretty much 100%closed. Boost dropped as rpm climbed. Air was much worse on the aluminum heads pass in the 80's. 60* and good air for the iron heads pass. Both at LVD. If I had more turbo and was able to run the gn1 headed engine @29psi out the back it would have made at least another 75hp. With a different cam and more turbo the aluminum heads would show an even greater advantage. For your 130mph (or slower) engine that revs to 5400 you won't see much with aluminum heads. I barely touched on the performance benefit of the gn1's. With even more cam and turbo there is a huge advantage as the car starts to make enough power to trap mid 140's and faster and is spending all it's time over 5800rpm during the pass.
 
ditto....thanks for the info and real world comparison.....no need to change here gonna leave my irons they work well!
 
If you already have the alum heads & don't have irons I would definately run the aluminum heads. I believe most of these opinions on here are based on you selling Irons to buy alum.
 
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