GN1's ported or not

TURBOGTA1

Life is Sweet !!!
Joined
Mar 31, 2004
Motor has been running great with the iron's, it's time to step up to the GN1'S
Just debating on the GN1's out of the box, or the ported version with ported stock intake for an extra $925 !!!! I have some good stuff on the motor including 70gtq turbo, Precision front mount, Accufab upper & 70mm,
Girdled 109, 020 over J.E pistons with forged crank.212/212 roller.
Is there an increased difference between the two with combo!! ($925+)
Or will the ported version be an overkill
 
TURBOGTA1 said:
Motor has been running great with the iron's, it's time to step up to the GN1'S
Just debating on the GN1's out of the box, or the ported version with ported stock intake for an extra $925 !!!! I have some good stuff on the motor including 70gtq turbo, Precision front mount, Accufab upper & 70mm,
Girdled 109, 020 over J.E pistons with forged crank.212/212 roller.
Is there an increased difference between the two with combo!! ($925+)
Or will the ported version be an overkill


If you are coming from a good set of ported irons, I would go with ported GN1s. I would doubt that the difference between a good set of ported irons is too far down from out of the box GN1s. I don't know if there is such a thing as overkill with great flowing heads and forced induction. I would love a set of ported GN1s if it was in the budget. :)
 
Marc87GN said:
If you are coming from a good set of ported irons, I would go with ported GN1s. I would doubt that the difference between a good set of ported irons is too far down from out of the box GN1s. I don't know if there is such a thing as overkill with great flowing heads and forced induction. I would love a set of ported GN1s if it was in the budget. :)
What I meant by overkill is my motor will be a 6000-6500 rpm motor,
and wasnt sure if the ported version will only benefit starting around these levels and above.
 
I would ge ported,either way in the future youll wich you did, I also dont see a big gain from real good ported stockers to un ported gn1s
 
My combination and yours are almost the same with yours being a little better. I was using stock ported heads (I ported them) and run the times listed in my sig. I was afraid out-of-the box heads wouldn't show me the improvement I wanted to see so I opted for the full race version and matching GN1 intake.
 
I was in the same dilema as you. I could barely afford the heads let alone any options. I decided to bolt them on "as cast" and I plan on getting them ported and upgrade to beehive springs next time they're off. I did pick up with them but I went from a 67p to a 70p also.
W
I compared the ports to my very good irons with my calibrated eye and didn't see much difference.
 
how about some flow #'s?

My ported stockers are at about 210 at .500 at 25 inches (I think - there were 2 flow rates and I am going by the lesser pressure). Do not recall the flow at lower lifts but it seemed like the aftermarket heads were just a bit better at lower lifts and about the same at .500, right out of the box with no porting. The roller should keep things closer-longer at the 500" area.

Are they CNC ported? It looks like it would be very easy to hand finish the CNC heads at home by just taking out the machine variations left by the CNC job.
 
Were you using roller rockers-dont think you can use the same rollers on the gn-1 heads-another added expense anywhere from $450-$650. for new rockers.
 
Ive gone this far, It's just money ;) Im going with the ported version GN1's, stock ported intake, and beehive springs!!!!!!
I need the manufacture/part numbers for the cometic head gaskets.
Block is 020 over.
 
49-blues said:
Were you using roller rockers-dont think you can use the same rollers on the gn-1 heads-another added expense anywhere from $450-$650. for new rockers.

Going with the Scorpion chevy style roller rockers, under $300 for kit
 
chevy rockers

Where are getting your chevy rockers at? do you have any pics of the rockers and info on them. thanks craig.
 
why not save a few bucks and have an outside party port the heads?
i could put you in touch with a guy from TX who does kickass work for minimal money. hes repairing my GN1R's for me and assembling them. he has an unpecable reputation also. his name is Lloyd Elliot. he does alot of small block chevy stuff, mainly LT1/LS1. his LT1 cars are putting down over 400 @ the wheels on a regular basis now naturally aspirated

the more uninterrupted air you can move, the more power you can make
 
ported heads

Hey steve maybe you could give us some flow numbers when he is done.That would be nice, if you dont care too.
 
simple said:
why not save a few bucks and have an outside party port the heads?
i could put you in touch with a guy from TX who does kickass work for minimal money. hes repairing my GN1R's for me and assembling them. he has an unpecable reputation also. his name is Lloyd Elliot. he does alot of small block chevy stuff, mainly LT1/LS1. his LT1 cars are putting down over 400 @ the wheels on a regular basis now naturally aspirated

the more uninterrupted air you can move, the more power you can make
Ive learned the hard way in the past, that it dont pay to try and save a few bucks, Id rather spend the extra buck and let the guy who makes them, port them!!!!!!
 
WINDMILL said:
Where are getting your chevy rockers at? do you have any pics of the rockers and info on them. thanks craig.

Most the vendors on this board carry the Scorpion's including Champion
 
WINDMILL said:
Hey steve maybe you could give us some flow numbers when he is done.That would be nice, if you dont care too.

hes not porting my heads, just repair and assembly. but i know with stock casting LT1 heads, hes getting ~240 @ .400" and ~275 @ .600" on the intake. with a 2.00/1.56 valve combo. thats basically the maximum for a non welded stock casting. and those are like $1400 assembled.

basically he does awesome work for cheap
hes done a couple sets of GN1's before
 
TURBOGTA1 said:
Ive learned the hard way in the past, that it dont pay to try and save a few bucks, Id rather spend the extra buck and let the guy who makes them, port them!!!!!!


i hear ya but if that were the case, AFR heads would rule the world. they dont do nearly what they claim to straight out of the box.

good luck with it :)
 
I did not really see a gain going from unported GN1s to fully race ported set. the car just never picked up.

If you are not racing a class then the best bang for the buck would be to go with the unported 14 bolt GN1s and scorpoin rockers and run their intake. instead of a stocker. you could purchase all of this for just one set of ported GN1s
 
simple said:
why not save a few bucks and have an outside party port the heads?
i could put you in touch with a guy from TX who does kickass work for minimal money. hes repairing my GN1R's for me and assembling them. he has an unpecable reputation also. his name is Lloyd Elliot. he does alot of small block chevy stuff, mainly LT1/LS1. his LT1 cars are putting down over 400 @ the wheels on a regular basis now naturally aspirated

the more uninterrupted air you can move, the more power you can make

I can concur about lloyd elliot, super guy, great work, big in the impalaSS world. He will be going through my LT4 heads.
 
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