ported irons/GN1 aluminum or go alchohol?

[bradofflorida]

I am trying to choose between GN1 aluminum or ported stock heads(with matching intake), or just going with an SMC alky kit(progressive) and pumping up the boost. From my previous experience, I am inclined to go with the heads, as they are maintenance-free once in the car. I can also get more power with the same boost. Price is not a big consideration.

I have the following questions:
Will I have to upgrade the turbo to match the flow of the heads?
Will either of the heads hurt low-end power, thereby requiring a higher stall converter?

I would like to stay with the driveability of the stock convertor and power curve. I also may go with higher displacement when my original shortblock goes, either a TA aluminum block or a stage block if I can get one.

Current combo: 87 Turbo T, stock turbo, stock intercooler, unopened short block, XP pump, volt booster, FP regulator, Red Armstrong Chip, 160 degree thermostat, Iceman intake, hooker exhaust. Engine and tranny are tight.

Thanks for the help!

 

[turbosam6]

I vote ported iron heads. And since I've had every item you listed, I should know. GN1's- not worth the hassle. Alky- cool, but not worth as much as ported heads. Now alky and ported heads- that would be nice. Get some from Nick Micale (heads, that is), and buy the alky kit. You'll still be under what Champion gets for ported irons, and have a nice setup.

 

[Razor]

Wow..St Pete ha

Too different trains of thought. One increasing airflow thus reducing boost at the same power level doesnt negate your octane requirement.

In other words, 400 HP is 400 HP..you need the octane to run 400 HP. If at 10 PSI or 30 PSI..you still have an octane requirement.

Now advantages to running lower boost are turbo doesnt heat the air as bad, and becuase of this, you may make a little more power on 93. But no where near the alky advantage of running 10 extra PSI of boost.

How bout explaining it this way, one of the top GN racers ran 10.40 at 17 PSI. Do you think cuase its 17 PSI he could do it on 93 octane.. hell no.

Lastly if your motor has never been opened for HG replacement, changing the heads opens pandoras box for head gasket replacement. Get a zipper.. once you crack that majic factory seal..its downhill.

Suggest you maximize your current combination via race gas or alky and move from there.. Once your in the mid 11's.. contemplate heads

Stock converter will be tough with any aftermarket turbo as far as spool, cept the TA49. If you get your converter restalled to a 2800 then a TE44 ar PT51 will getthe job done. Times in my sig are PT51 and 12 inch protorque converter.

BTW, the SMC progressive is designed with imports in mind. Not your turbo Buick... Look in the alky section of the board, or click the link below.

Plus in St Pete.. i'm alky
HTH
If ya need tuning help or ?? Hollar

Julio

 

[azgn]

Razor! you get an A+

right on!

ported heads ain't gonna do it without octane

(well, 200 more cubic inches would help....)

I ain't buyin "stock"........

 

[Razor]

Originally posted by azgn
Razor! you get an A+

right on!

ported heads ain't gonna do it without octane

(well, 200 more cubic inches would help....)

I ain't buyin "stock"........

Aww shucks.. i'm blushing

Build a 540 cubic inch big block Chevy if you want power on 93 octane

 

[JDSfastGN]

i agree that you will see bigger gain with alky verses heads on 93 octane, but you 400 hp does not always require the same octane requirments as stated i can run 25 psi on a stock motor and a 44 and make 400 hp or go with GN1 heads and a 61 and probably make 400 hp but at 18 psi which you could run on 93 octane with a good tune. And having ported heads vs stock heads on a similarly equipped car , the car with heads will be able to run the same amount of boost on 93 but flow more air and thus make more power. Keep in mind this is apples to apples both having an optimum tune.

 

[Razor]

18 PSI isnt 18 PSI only as it relates to a totally stock GN. These cars can barely run 16 without pinging..some 18..some 20..some 25 with no knock sensors

I disagree that you can run 18 PSI on a heavy breathing GN motor on 93 octane "and make power"..not running 830's for O2's. But 760's.. call it what you will..octane requirement..else you pop them HG's like balloons.

POP

Big difference in lean and mean vs rich and safe at 830 land.

 

[JDSfastGN]

ok i see this is only one persons 1st hand results verses another, down here on 93 i can run 18-19 with my current set up in the sig with 02s in the 800s and no knock, i do not know anybody that runs 760s on 93 octane , that is on the verge of lean and being a little richer to be safer does not negate the gains of a heavy breathing GN

 

[Razor]

Finally GOTCHA

800's your in the 13's.. 760's your in the 12's. Huge HP difference.

factory chip is 26 degrees at WOT, so you drop it to 20 degrees street chip, fatten it up..BAM you run 18 PSI but dont go fast.

So is 760's at 16 PSI faster than 800's at 18 PSI?

could be.....

Told ya 18 PSI isnt 18 PSI..cuase if one car is at 750-760 and the other is at 800's the 800's car is 5 cars back

Like I said .. making power..

Your fighting the octane issue..you will always lose to detonation.. everybody has..address it or else..new topic..

"What are the best head gaskets"

Cheers..been fun

 

[JDSfastGN]

sorry razor i disagree 02 readings have a large margin of error and 760s and 800s does not make or break a 12 second car, i do not know anybody even with 14 psi that safely can run 760s 02 and not be on the edge, yes you are fighting ocatane but 800s is a nice air fuel ratio for 93 and you will make a lot more power. Sorry the car with 800s is 5 cars ahead because the guy running 16 psi and running lean still does not have enough fuel and pop goes the gasket. 02s are not constant and 760s on a stock turbo are just as lean as 760s on a large turbo EDIT : sorry fixed it , i had wrote large turbo twice

 

[Razor]

I dont see 1/4 mile times in your sig to backup your statements. Or time slips.

Get 500 passes down.. you can argue all you want. The diffeence at the track is huge. EGT's at 800's are the mid to upper 1400's. egt's at 760 are 1600-1630 typically..1/4 mile speed difference between the two states of tune is approx 4-5 MPH.

= 50 real world horsepower.. sorry you want to maximizes 93 by inflating boost numbers with a tuneup thats rich. I've seen plenty of modded GN's run high 13's at the track becuase of XYZ..

Anyone else want to backup these statements?

So you drop 100 octane fuel in your GN at 18 PSI, drop fuel pressure to get you into the target 1600 EGT numbers.. you are 1/2 second faster +3- 4 mph improved..at the same boost level..same chip.

Wanna bet?

I see the same numbers at the race track twice a month..

Hope this helps you into the 11's.

 

[JDSfastGN]

Razor i have not had my car to the track, ive helped a lot of people though, im not gonna bring up the "ive been to the track more blah blah" you are right about leaner is meaner, but there is a certain point where you are as lean as you can go on 93 octane, and 760s does not work on the STREET . At the track i have no doubt you shoot for 750s or 760s on race gas because you can cover with the octane but on the street you have to cover it with fuel pressure. I stated you would see more a gain with alky, but i already stated my point that 400 hp does not always require the same amount of octane on differnet set ups. There is no argument about this, 18 psi on a heavy breathing motor is the equivalent of running 21-22 psi on a stock motor, so you tell me who is going to run faster with the same 02s. both have to have about the same 02 and EGT numbers to run safe on 93 right?

 

[Razor]

Running safe means your running less power. See safety comes by detuning/reducing power so the fuel being used can be maximized. No.. 18 PSI on a heavy breathing motor is equal to 32 PSI on a stock motor.

Case in point Roy Garcias car went low 10's at over 130 MPH at 21 PSI. See the heads and cam taking action. I bet that car would ping on 93 at 8 PSI.

So a lazy tune is that, one that fattens the motor up to achieve a boost number, but boost doesnt equal speed when the tune-up is fat. If you need to make power on 93 octane gas by itself, you have the wrong vehicle.

Its how it is..I didnt write the book..just follow the foot steps of those that have been there and done that.

Thats how you make these cars fast..octane..via race gas or alcohol/propane injection.

 

[JDSfastGN]

i bet his car can run no more than 8 psi on pump gas as well, but his car was built for race gas and of course probably has a turbo that loves the bigger boost and higher compression. 800 is not fat on pump gas, on race gas yes, but the whole point was pump gas and you CAN NOT run 760s safely. Our vehicles are not the greatest on pump gas but that is not the argument, and you are manipulating it into something that is common knowledge. But a similary equipped car with heads verses one with stockers , the car equipped with heads will flat out beat the stock headed car running the same psi and the same 02s.

 

[ijames]

Julio, I have to disagree with your hp-octane statement. I almost exclusively use and tune with 93 octane on my car, with no alcohol/water injection, and I tune on a few friend's cars that run race gas and/or 93 octane, so I have a decent experience base to draw on. On my car, as I improved the flow capabilities I could make more power at a given boost, run more boost at the threhold of detonation, and run leaner as well. I started with a TE34 turbo and big neck stock intercooler, could run 16-17 psi boost in 3rd gear (all boosts will be in 3rd gear), and got my best hp at about 805 mV on the O2 sensor. I could run 13.2-13.5 at 102-102.5 mph in that trim (the mph is more telling of hp; my car doesn't hook that well). I switched to a CAS V2 frontmount, and like I said, made more power at 17 psi boost, and was able to turn the boost up to about 19 psi. Mph went up to about 105-106 but I was out of injector at that point; best power was at about 790-795 mV. Bigger injectors made 106 mph typical and let me keep the O2's at 790-795. Then I switched to a PTE54 turbo and THDP and after retuning everything, I run typical 12.30-12.50's at 109-110 with a best of 12.15 and 111.0. This is at 23 psi in 3rd gear with O2's in the 770-785 range, with no or at most 1-2 deg of retard on the 2-3 shift. I run 20 deg of timing at wot in all gears, about 24-24.5 psi in 1st/2nd, and with me and all my junk in the car typical weight going down the track is 4050 lbs or so.

On one friend's car he has gone from stock to ported irons to GN1 heads to well-ported GN1s, from a PT51 to a T66 turbo, and from stock to CAS V2 to Cottons frontmount. He normally runs race gas but also uses 93 occasionally, and while I can't give you accurate numbers like I can with my car, we saw the exact same trends. More efficient turbo and intercooler makes more power at the same boost and lets you turn the boost up some. As he improved the heads he was able to make the same power at less boost, and again turn the boost up to make even more power. He's run mid-11's on 93 octane at about 118 mph, and over 123 mph on race gas so far (he needs bigger injectors again).

My impression is that of course every combination will have its boost and power limit on 93 octane, but that anything you do to improve the efficiency of the airflow will raise this boost limit and also raise the hp limit on 93 octane. In no way am I saying that you can make as much power on 93 octane as you can on C16, but if you are careful you can go pretty quick with just 93 octane. A year or so Jack Cotton posted that he ran a high 10 on 93 octane at some low boost and low timing, I think it was under 20 psi, when his car was running mid-hi 9's turned up with race gas.

 

[GNFURY]

dude, get the ported iron. They will be the building blocks for the effectiveness of future mods.

 

[G-Racer]

GNFURY speaks the truth!!!

 

[Bmason]

Champion CNC and alky!

Brad:

I think you need to really define what you're going to do with the car long term. You want to stick with the stock converter and drivability, but may go SG2 or TA/aluminum block eventually. That's a longs ways from stock!

I think you'd be happy with a set of Champion heads and alky. I run Champion CNC heads on my cars and I have no experience with the GN1s (yet). I can run 18-20 psi on pump gas (believe it or not). If you tune the car properly, you can and will be able to make decent power on pump gas. No, you will not be able to run a "race" chip on pump gas alone, but with alky you can. I'd be willing to bet that with a "heads only" change, at the same boost level that the car will be a touch quicker and have the ability to run more boost overall.

What I'm getting at is that with a proper tune, with heads and alky your car should perform well. As Carl mentioned above, I know the car/person that he referred to. This guy's car is pretty fast but...there is another person that we both know that's running pump gas and alky. His car is "internally" all stock, and with alky and pump gas, he is darn near door to door with the modded car (aluminum heads, big cam, turbo, etc.) when they are both on pump gas. I personally think that's pretty good, especially since I've been on the receiving end of smelling the alky!

Go iron and alky for now.

-Bobby

 

[strikeeagle]

Higher HP must be the result of higher cylinder pressure, no? If you accept this, faster cars have higher octane requirements, irrespective of boost.

We have lots of handles - heads and alcohol among them, to help us "cheat" the laws of cylinder pressure, cylinder temperature and octane, which, when all is said and done, are all that matter so far as detonation goes.

 

[tminer]

Doesn't rpm come into play? Won't ported heads move up the power band and allow addittional rpm and see gains that way even if cylinder pressure has remained constant?

Tom