Can an unported 2g head make 500+whp?

[jkimes]

My car is at Polk Performance right now about to be dyno tuned and I need advice on weather or not to have the head ported and upgrade to larger valves before I get it tuned. Does anyone know how much horsepower is possible with a built 2.4 and an unported 2g head?
I'm using an scm-6176 turbo and a 2g ported exhaust manifold and I'm hoping I can max out this turbo setup without spending the extra $1500 for head work and larger valves. I'm currently using a fresh stock 2g head with new stock valves, (bent the old ones when the the Tbelt tensioner failed ) FP3 cams, and FP dual valve springs and retainers. Im also using stock 4g64 cam gears. The bottom end is already built to handle anything I could possibly throw at it.
Can I reach my horsepower goal (500+whp) with the unported head and stock valves or will the extra displacement of the 2.4 overflow the capacity of the head causing it to choke?
Also, do I need the adjustable cam gears to try and move my powerband further left or will the standard 4g64 gears suffice with the large fp3 cams?

 

[Street Surgeon]

You'll get more out of a valvejob (3 or 5 way) than a port/polish on the head, when you had new stock valves put in did you get a valvejob done?

 

[erald01]

i don't think the head will allow you to make 500whp or more, because it will restrict the air flow, and thats why a lot of people go with the 6 bolt, because the head it what make most of the difference. 6 bolt head will flow a lot better than 7 bolt.

 

[absolute_DSM]

i don't think the head will allow you to make 500whp or more, because it will restrict the air flow, and thats why a lot of people go with the 6 bolt, because the head it what make most of the difference. 6 bolt head will flow a lot better than 7 bolt.

That isnt true at all.

People usually go with a 6 bolt because theyve been scared by "crankwalk". The 2g head has smaller ports which allow for a higher velocity at lower RPMs. The 1g head has larger ports which allow for more air to be moved at a higher RPM. Not the best design, but it seems to do the trick.

I dont see any problem with using a 2g head for your goals. Just talk to TPG Performance. Nate has done it over and over again without issues.

 

[v413nc3]

1G heads are complete junk. Larger ports don't mean more airflow. The head will do 500whp just fine. The evo ports are a bit smaller than the 2G ports and they do well over 500 on stock unported castings. Later when you choose to port the 2G head you'll have a much better platform. The 1G has a bad angle of approach and you loose a great deal of velocity.

 

[erald01]

What you mean larger ports dont mean more airflow? Then why do people port their heads, BECAUSE they want more air flow. BTW the evo ports are not smaller because when i had my car apart i compared my head to my buddys evo and the EVO head is a lot better design and flows more air. More air and more fuel mixture means more power, its the basics of any engine.

 

[absolute_DSM]

1G heads are complete junk. Larger ports don't mean more airflow.

You act like you port and polish heads for a living.

Larger ports allow for more airflow at a higher RPM but kill velocity in lower RPMs. Guys pushing 10k RPM would see a choke with a 2g stock head and probably some more gain with a 1g stock head just because of port size.

D-shaped ports are a great comprimise. A 2g head with D shaped ports would be ideal for all of us.

 

[bastard dsm]

you need to do more research erald ^^^^^

 

[v413nc3]

You act like you port and polish heads for a living.

Larger ports allow for more airflow at a higher RPM but kill velocity in lower RPMs. Guys pushing 10k RPM would see a choke with a 2g stock head and probably some more gain with a 1g stock head just because of port size.

D-shaped ports are a great comprimise. A 2g head with D shaped ports would be ideal for all of us.

Seriously if you are pushing a 10K engine and you have an unported head your name is either Marco (yes he does it) or you're on the uber budget build. 500whp engines do not run 10k normaly. The question was, can it be done. The answer is yes. And yes the 2G head with D shaped exhaust ports is rather nice. I run one.

 

[Boo5t_Addict]

2g heads actually have a better overall design. Whereas the 1g head has larger intake ports, the angle in which the air goes into the combustion chamber is more extreme. The 2g head may have smaller intake ports, but because the pathway the air flows into the combustion chamber is less extreme, and therefore velocity is up. 1g heads will give you a slightly higher peak hp rating, but a 2g head gives more area under the curve, and not just at low rpms.

 

[absolute_DSM]

The question was, can it be done. The answer is yes.

Youre right there, thats the question and I agree it can be done.

But there would be great gains playing with the head.



Just noticed an interesting article, they even mention the 4g63 1g head.

Secrets of the Cylinder Head - Tech - Sport Compact Car Magazine

 

[jkimes]

My bent valves were replaced by my machine shop free of charge after my tensioner failed, so I'm pretty sure they did not do a valve job in the process... my machinist likes me... but not that much.

btw.. What about the 4g64 cam gears? Do I need 2 buy the ajustables in order to tune 4 the most power, or will the stockers work fine?

 

[gixxerdrew]

I did 516whp on a stock 1g head and the 2g head is known to be a better design. That was with just a 60trim. The stock heads can flow. I had a "ported" head before and I actually made more power on a stock head. I realized at that moment that a lot of joe blow machine shops don't have a clue.

 

[Zex4g63]

I work for a machine shop. Mostly big block stuff. We spend more time filling the ports back in than taking away. Bigger is not always better.

 

[twicks69]

Jkimes - The 2G head can easily make 500whp. The turbo you have with its mitsubishi turbine housing will have a major difficulty making past 500whp though because it does not flow jack past 26psi and 500whp unless you change over to a T3 or T4 turbine housing. I have done it years back, and the head wasn't a restriction; the turbine housing is. As well, your 2G MAF will be a restriction past 500whp. You should upgrade to a manifold absolute pressure sensor (MAP sensor) as it will help you flow alot more, and will allow for faster spoolup if you are using a 4" intake pipe and a large air filter.

Adjustable cam gears will allow you to get more out of the powerband by being able to fine tune your spoolup/low end torque vs. top end HP. They are a definite benefit.

 

[blcknspo0ln]

I will most definitely back Tim up on that. My 50 trim DOES NOT gain any life after 26 psi. I've tried to boost up to 30psi with no avail because of the smaller mitsu housing. Although that's not to say that at 26 psi the mitsu turbine housing can't deliver a big punch, just not as much as a t3 or t4 can.

Tim, in your opinion, at what point do you think the 2g MAF becomes a restriction? (hz-wise or airflow-wise) Also, when you talk about using the MAP function, are you tuning with DSMLink or EMS? Reason I ask is I only use my MAP sensor as a boost reference and aren't really using it to its fullest potential.

 

[jkimes]

Thanks for the reply's everyone. I'm a little strapped for cash, and leaving my head alone (for now anyway) should save me quite a bit of money. I realize my mitsu hotside sucks and will be a restriction, but my goal for now is only 500whp. I wasn't sure at what point the stock head and valves would restrict power, but it sounds like they should get me to my goal. In the future if I decide I want more power I'll probably switch to a divided t4 mani with a ts 35r or maybe a gt4088r as well as a maft and a 3.5" gm maf. At that point I'll have to spend enough money on other parts that I'm sure I'll just go ahead drop the extra cash to have the head ported and a valve job done.

Is there any particular brand of cam gears I should buy? I'm thinking about using the fidanza adjustables.

 

[2gGSX]

Is there any particular brand of cam gears I should buy? I'm thinking about using the fidanza adjustables.

Those would be my choice only because of the fact that everything is kept where it is by 5 bolts vs. for example, 3 with the HKS purple gears.

Tim, in your opinion, at what point do you think the 2g MAF becomes a restriction? (hz-wise or airflow-wise) Also, when you talk about using the MAP function, are you tuning with DSMLink or EMS? Reason I ask is I only use my MAP sensor as a boost reference and aren't really using it to its fullest potential.

He is talking about a standalone system. FakeMAS is only active above the switchover point, which is supposed to be as close to full boost as possible. If you were thinking of setting it at a low enough airflow value to force it to be active all the time, well, then you are trying to extrapolating a lot of data between 100 hz and the 2400+ that you would see in full boost.

Thus, even with FakeMAS and the MAP data utilized, you still really need the MAS/MAF in order to function correctly off boost and before peak boost.

 

[slugsgomoo]

I have a 2.4L w/2g head. head is basically stock with bigger valves, supertech duals and fp3's. w/fp3575 this setup made 636 AWHP in my buddies car and it still had some room to tweak it a bit. Fairly similar to your setup on the head side, including the 2.4L cam gears. I'm sure that having some adjustables and getting them degreed right would help too.

The truth is that the 1g head flows more up at the top stock for stock, but the angle on the valve & port shape on the 2g head is vastly superior. Couple that with the possibility to port for more flow, you end up with a superior design. Evo heads have more in common with 2g heads in that way, but larger ports.

 

[twicks69]

I will most definitely back Tim up on that. My 50 trim DOES NOT gain any life after 26 psi. I've tried to boost up to 30psi with no avail because of the smaller mitsu housing. Although that's not to say that at 26 psi the mitsu turbine housing can't deliver a big punch, just not as much as a t3 or t4 can.

Tim, in your opinion, at what point do you think the 2g MAF becomes a restriction? (hz-wise or airflow-wise) Also, when you talk about using the MAP function, are you tuning with DSMLink or EMS? Reason I ask is I only use my MAP sensor as a boost reference and aren't really using it to its fullest potential.

The 2G MAF becomes a restriction in both ways hertz levels get easily maxxed, and the inlet turbulence is increased with it in the intake tract. Taking it out of the equation, running MAP with AEM EMS was able to pull nearly 20-30HP using a FP 4" intake pipe and large K&N filter only. You can do 600whp on a 2G MAF and DSMLink, but it is a restriction for sure. Also, I am not too keen on using MAF-Translators and GM MAF's -- it is still an airflow restriction placed in a different location. That is why I reccomend using the AEM or equivilant standalone with a MAP sensor and AIT sensor.

As well, the SCM6176 did make a very streetable turbo on 22-26psi, producing 500AHP/460tq at 26psi on 110 octane with an extremely conservative tune, with the mitsu-flange on my stroker. It had excellent midrange, but it severely lacked breathing room up top (6000rpms and up), and couldn't flow anything past 26psi. I could only do 11.5's@122mph. When I changed over to a DN Performance T4 tubular exhaust manifold and a 0.81A/R T4 turbine housing with a V-band downpipe, I could run the turbo to its fullest potential. As an example, it was then capable of running 11.0's@133mph at 35psi in a full weight 2G street car.

Check out this old thread that talked in detail about my Precision turbo experiences and performance levels attained with each one:
http://www.dsmtuners.com/forums/tur...pte-6152e-dyno-1-4-e-t-s-2.html#post151107265

I hope that this helps you with your decisions in the future.

Either way, the cylinder head is not a major restriction right now. If you changed over to a 1G head, you would likely lose spoolup time (slower), lose midrange torque and HP, but gain in power in the top end rpms on the head.

Even then, a 1G unported stock-size valve head with springs/retainers and 272's can easily flow 1000HP. I just changed over to a fresh 1G head, still unported, with 1mm oversize valves, dual springs and 288 cams and yes, I did see gains, but only like 20-30HP so far -- great gains, but if you want to save your money for a little, you will be just fine.

 

[dsm-onster]

"superior design", "junk", "port velocity", "port angle". . . Alot of you have thrown around phrases and added them up to equal "2g head is better". No one has given any proof. . . Hasn't Curt Brown rolled out 499whp with an evo3 16g? Which head does he use. Why would he not have used a head 'better in design' than a 1g head? He took the evo3 16g whp record with an UNPORTED 1g head at 449whp.

The intake port angle theory is negated by the steeper intake manifold runner angle of the 1g head. . . And, port velocity is not a measure of volume/min but how fast EACH PARTICLE moves. Any decent boost coupled with decent intercooling causes much more density. More density means that a larger diameter can induce speeds of a smaller diameter at stockish boost/intercooling. . . Back to port angle. A SMIM on either head with their 'straight line attack' on the head runner will negate the shortside radius/portfloor even more between the two.

From my experience and training, I see the portfloor of the 1g head GREATLY increasing the tumble of the intake charge as it enters the CC.

 

[jkimes]

Since my mitsu hotside is going to kill all my top end power, do you think I can make 500whp with my current setup on pump gas since I won't see any significant gains over 26psi anyway?

 

[dsm-onster]

There are SEVERAL setups with bolton hotsides with ported 2g exhaust manifolds and stage3/stage5 turbine wheels doing over 500whp. 2g head and 1g head. . .

Go with what you have. See what you come up with. Let those results take you to the next upgrade.

 

[jkimes]

I intend to "stick with what I have", I'm just hoping I can achieve those numbers on pump gas since I won't really benefit from turning up the boost past 26psi anyway and race gas isn't exactly easy to get in my area. Has anyone aside from the TPG guys achieved over 500whp on pump with a similar setup, or will I have to run race gas or meth in order to advance the timing enough to make that much power?

 

[twicks69]

I intend to "stick with what I have", I'm just hoping I can achieve those numbers on pump gas since I won't really benefit from turning up the boost past 26psi anyway. Has anyone aside from the TPG guys achieved over 500whp on pump with a similar setup, or will I have to run race gas in order to advance the timing enough to make that much power?

There are plenty of people who have done 500 on pump. Heck, I did it with a mix of 93 and 110 octane (used only as a preventive measure if detonation occured), with a conservative map on a 2.3L -- I was only running 8 degrees of timing at 26psi. (Dyno graph attached - 497whp/459tq) The tune had absolutely no detonation or power differences on 93 octane only.

Parts used: PTE SCM6176SP, 2G Ex. manifold, 1G stock head, 264/272 cams, magnus 1G street intake manifold, 2.5" IC pipes w/ PTE large core, 880cc's w/ walboro 255, AEM EMS, 9.0:1 compression 2.3L Eagle/Ross combo.

You will get close if your setup is all working properly.

FYI -- The 50 and 60-trims are much more efficient up to 26psi than the SCMzzzz61 --not a typo -- it is a slow spooling turbo that isn't fun really until after 26psi. It is NIGHT AND DAY when I swapped over to T4 on the turbo, and turned up the boost. It increased my MPH in the 1/4 by 11mph from 122 to 133mph! The 50 and 60-trims have been proven to do 450-550whp on well put-together setups at similar boost levels, but they definitely run out of steam after 26psi.