is it true

[BoostNV]

I was recently told that the most horsepower that I can get out of my 2g without changing the head is 332hp.....is that a fact?

 

[Randomrage]

I dont know about the 4g63, but on the 420a its rumored to be around 400hp. But, why would you want to go over 300hp on a stock head anyway?

 

[BoostNV]

It's that I was really against having to change the head it just wasnt' somthing that I had actively thought about. if it needs to be done then it will need to be done.

 

[clownface]

how in the hell.... no, the actuall number is 421.31 HP till your head is junk.
Ive never heard that before to tell you the truth, all i know is that ive heard that the 7bolt 4g63 stock can handle 400+HP and still be reliable and the 6bolt can handle even more.

 

[FourG63 97GST]

why would you not want to?

 

[Randomrage]

why would you not want to?

Um, because Id rather upgrade something in the first place than have it break and take out other parts with it down the road?

 

[FourG63 97GST]

yea since heads break alot

 

[sonicnofadz]

Ummmm correct me if I'm wrong but the stock head can handle a whole HELL of a lot more than a measly 300 hp. I've ran 300 hp on a stock head before (all stock, using big 16G) and had no problems whatsoever. It was my daily driver. If you read further into this, you'll find that there exists 10 second cars using all stock heads. Just because YOU CAN do this, doesnt mean its the best or most efficient. The stock head could definetly benefit from better cams, porting, lifters, larger valves, and stiffer springs. If the head is left unported and you start making ridiculous power say in the 600-700 hp range, then you are missing out on some serious power gains (the small exhaust and intake ports will bottle neck the air flow into and out of the engine). For moderately powered engines the stock head should perform nicely.

 

[Randomrage]

yea since heads break alot

Just because YOU CAN do this, doesnt mean its the best or most efficient. The stock head could definetly benefit from better cams, porting, lifters, stronger valves, and stiffer springs.

Thank you.

I guess NOBODY here has ever had a shot valve. And 300+ hp on stock cams is an everyday thing.

 

[sonicnofadz]

Actually it isn't at all difficult to make 300 hp on a dsm. A 16G, Full exhaust, 550s, SAFC, and a manual boost controller will get you to 300 HP or damn close to it. For alot of people in this forum 300+ hp on stock cams is a VERY common thing. Alot of people choose to run stock cams over aftermarket to retain a stock like idle (use of aftermarket cams can cause a rough idle) and not to mention that aftermarket cams are expensive as all hell and generally don't yield much peformance gains for the cost ($500-600 for intake and exhaust).

 

[psychlow]

Thank you.

And 300+ hp on stock cams is an everyday thing.

For us turbo guys, it very much is.

All you need for 300HP on a turbo car is a fuel pump, exhaust, and boost control. 400HP is achievable on stock cams, according to the tuning guide.

 

[Randomrage]

A 16G, Full exhaust, 550s, SAFC, and a manual boost controller will get you to 300 HP or damn close to it.

Agreed.

not to mention that aftermarket cams are expensive as all hell

Ok, lost me in the contradiction. Aftermarket cams are expensive as hell? Full exhaust will run you $500 upwards. Hmm....

Anyway, personal preference I suppose. Whilst building my engine I fully intend to fortify the entire thing. I dont like leaving stuff to chance, or waiting till it breaks to fix it.

 

[Syndicate13]

Anyway, personal preference I suppose. Whilst building my engine I fully intend to fortify the entire thing. I dont like leaving stuff to chance, or waiting till it breaks to fix it.

Then your one of those guys destined to have a slow car. You'll spend more money on "making it safe" than people on here spend to purchase the car and run 12's. It's no secret to making DSM fast. Ever wonder why in the tuning guide it doesn't say to "rebuild the engine and head with all forged, lightened parts or it will explode!!", it's cause you don't have to. Fact is for 90% of all people on here a stock motor and a 16g is all you'll ever need to be perfectly happy. All these people building forged motors and running huge turbos, throwing money left and right at the damn thing will not be any faster than the other guy usually.

Case in point, my mods are in my profile, there is a kid here with a 95 GST with a huge Ebay FMIC, MAFT, AFC2, a straight T4 turbo with a 1.32 A/R(yes you read that right), and numerous other uber-expensive and uber-unnecessary parts thrown at it. Wanna know what happens when we race? I wave at him the whole time as he desperately tries to pull away from me. He has more in electronics on that car than I have in mods, minus the tranny, yet he isn't any faster. Now I'm not trying to say that my car is the best and I know what I'm doing because I learn everyday when I come here and read. However I am saying that people do know what works and what works well. So yeah, you can build a motor that will handle the stress of 900+ hp but if you only plan on running 12's then what's the point?

 

[sonicnofadz]

Sorry about the above, I left things unclear. Yes cams are expensive. Yes full exhaust is expensive. Actually a good set of performance camshafts will cost you about the same amount as a performance exhaust system (downpipe to muffler), but when you install a full exhaust on a turbo car, the performance gains are VERY substanstial. The larger exhaust diameter will increase power in two ways. First, the pistons themselves will face less retarding force pushing the exhaust gases out of the cylinders because the pipes they are pushing the gases INTO will be LARGER. Second, because of the higher flow rates of the new exhaust system, the turbine fan blades will be faced with higher forces and cause the turbo to spool up at a much lower rpm which will broaden the total powerband of the engine since boost will be created at a lower rpm and continue into the higher rpms. On the other hand, installing the cams won't neccessarily have huge power gains, especially for a car making near stock power (200-220 hp) since the lift duration of the stock cams really aren't causing a bottleneck in airflow at this type of "low power" (not as much gases flowing). To a low power engine, the stock cams are almost as good as an aggressively profiled cam. However what the performance cams MIGHT do (in fact most experience this ) is give you a really crappy sounding idle. This is why most street DSMs making "moderate" power choose not to upgrade their cams. The fact of the matter is, there are better ways to spend your $550 that will yield higher power gains for the money (such as a bigger turbo or bigger injectors or a full performance exhaust system).

 

[Randomrage]

Then your one of those guys destined to have a slow car. You'll spend more money on "making it safe" than people on here spend to purchase the car and run 12's.

Nice generalization. Guess thats why Im running a 75 shot on a stock 420a? Word.

 

[Randomrage]

All these people building forged motors and running huge turbos, throwing money left and right at the damn thing will not be any faster than the other guy usually.

Whoa, whoa, whoa. I almost missed this. Please explain this statement to me. Forged motor and bigger turbo + more money = slower car?

 

[cuttheduck]

hes just saying that if you're making a quick street car you aren't going to replace the head because you're putting out 280-320. He's saying that the head will not give you really any gains and the "relibility" it provides for a mildly modified 4g63 is practically nonexistent, maybe worse..... So what the point. Throwing parts on a car doesn't make it fast, its what you do w/ those parts and how they work together is what he was saying.

On paper modifying the head or other internals look great because you think, i'll just put in these rods or forged pistons and what have you and they can hold 600 horsepower. So then i wont have to worry about that component if i do ever put out that much power. So let say you're only making 300, you not only wasted money and didn't gain speed. you probaly lost reliabilty. the stock rods/pistons could handle your 300 horses so they were'nt in any real danger of going. Many times on a daily driven car added internal mods seem to cause more headaches then they solve. Yes the parts can handle 600 horsepower on a meticulously maitained race car but can only cause problems on a daily driver w/ stockers that weren't going any time soon. Hell, even a mess up in the labor that didn't need to be done in the first place can cause more probelms. Ask my bud why hes on his third engine, then ask him if hes had less or more probelms since trying to DD w/ ross forged pistons.

No the head will not need to replaced at 332hp. Someone really told you that exact number, nothing more and nothing less??? That may be a sign not to listen to them. A rule of thumb is good but an exact number that isn't close to right anyway,,,,WTF .

 

[psychlow]

Whoa, whoa, whoa. I almost missed this. Please explain this statement to me. Forged motor and bigger turbo + more money = slower car?

I think you may have misinterpreted it.... He said they'll still be about the same.

For the most part, most people who just go and throw money at a car buying the largest turbo they can afford and beefing up everything they can just for "saftey's sake" spend A LOTE more money and time in mods than a person who just bought a decent turbo, turned up the boost and knows how to tune - to produce about the same results.

Sure, tuning only gets you so far - but going 11's on a stock turbo (14b)? That's much faster than many guys here with 50-trims. That's rediculously faster than me and my big16G right now.

 

[Syndicate13]

Thank you guys for reading the post and actually comprehending it instead of scanning it for something to reply back to. I never meant that building a forged motor and running a correctly sized turbo wouldn't allow you to go faster, I meant that for the most part people that throw that much money at them aren't going to go any faster than the guys on stock motors. If you want to have a fun, reliable street car, then bolt up a 16g and supporting mods and keep up on the maintenance. It'll be fun and as long as you don't beat the hell out of it, it'll be reliable.

 

[sonicnofadz]

Yes, the story is sad but true. Alot of DSMers who have built motors still fail to recognize the importance of good tuning. I don't care what type of rods or pistons you have, if you run way too lean...your going to destroy your engine. Although there is also a point where the stock pistons and rods will no longer be enough to hold the power. It is rumored that some have reliably ran completely stock engines up to 550 hp with no problems. I know people personally who have gone above the 400 hp with stock internals without any trouble. But when you get into the 500-600 hp range and above, things really start to stress and break. It is around this power range that forged internals become a neccessity. Along with the strengthened bottom end, you need EXCELLENT tuning skills, because one small lean condition can be catastrophic at these power levels.
Ok, getting back to the original question:yes the stock head is good enough to withstand the punishment of a high horse power engine. The cylinder head itself isn't what most people worry about in a powerful 4G63 motor. It is the rotating piston/rod/crank assembly that most people suspect of failure. The crank and pistons move with much higher speeds than the camshafts, and the crank assembely has a lot more rotating mass. Because of the higher rotational speeds, and higher mass, you will find more destroyed main bearings and snapped rods than bad camshaft bearings or cracked valves (unless the timing belt slips, but thats a whole different story). So to put it simply, in high horse power engines, it is the block that one has to worry about and not the head, because the head has MUCH less rotational mass, and runs at a much lower rotational velocity and will generally be more trouble free than the block.

 

[kpt4321]

Besides upgrading cams, the stock head is good to well over 400 horsepower. I know more than one person (quite a few, actually) who are making 400 whp or close to it on stock heads with only cam upgrades.

300 horsepower on stock cams is EASY EASY EASY. You can do it with a 14b.

 

[92redman]

Some of you guys are saying a stock had head has to be upgraded after xxx hp or with x mods. You are missing the real point of upgrading a head. It doesn't really matter how much power you are making, what matters is the lift of the cams you plan on using and where you want your redline to be. In fact, even with upgraded cams you don't necessarily need new springs unless yours are worn out.

If this guy is not planning on getting cams(which is entirely unnecessary to make a lot of power) then there is no need to upgrade anything in the head until he runs out of other things to do, IMO. There is no set number at which your head can no longer take anymore power, it's more of a preference and where you set your priorities. Somebody mentioned the tuning guide earlier, if you follow that there is no need to upgrade cams to make 400+hp.

 

[midnght]

I was recently told that the most horsepower that I can get out of my 2g without changing the head is 332hp.....is that a fact?

No.