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My little 8v 4G15 maxed out at 6800 rpm's. bone stock, with cheap gas.

It was a 12 valver.

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thanks legolas337. how'd you find out? was that with the automatic?

does anybody know how much stronger or weaker the 8v is compared to the 12v? it would almost make sense for the 8v to be more robust: simpler design, less moving parts, less lobes on the same length cam. I'm not sure witch assembly would be heavier. anybody else have any theorys, or even experience and knowledge?

basic question: which head has a higher mechanical redline, 8v or 12v?

12v is better all around. More valves=more air can be flowed in the same amount of time=more power. It may seem like more to go wrong but with even just the people on this forum, we've logged (looking at the mileage thread) over 2 million miles on engines that have never been apart. They're both durable to the same extent, the 12 valve is just better for performance (what perfomance there is from the 1.5L that is).

The 12v head would be heavier but not by enough to make it that big of a deal.

There's also the size characteristics to think of. The 12 valve has more valves which means the valves are smaller and lighter which = less strain on the moving parts.

I know that the rev limiter for 91+ EFI 4g15 12valves is 7200rpm for US based vehicles.

oh, I have no doubt that the 12v head is an all around better head, but I wonder if, purely from a durability stand point, the 8valver might not be *tougher*. sorta like a volvo that just wont die (no matter how much you might WANT one to! the volvo, that is)

what I really want to know is, can you abuse a 8v to the same extent as a 12v. or even more? ie. max redline. I realize their respective power bands will fall differently, but redline is also about pure engineered toughness as well as efficiency.

Factor in heat range, more valves=more airflow which=valves don't get as hot=less operating temp=more durability. Then take into account that the 12v is the updated version of the 8v, more testing, better materials, more thought went into it for it to perform better, better oiling capability, etc. It's just "better" in every aspect.


Honestly, I don't see an 8v taking constant high rpm abuse as well as a 12v would and would advise against it.

8 v has less flow so 9000rpm would be kinda pointless. but then again 9000rpm was also kinda pointless with the 12v without the right cam to take advantage of it. past about 6500rpm the stock cam, power goes as flat as an ice skaters boobs. I just took it up past that for the cool sound and to kill the motor. to take advantage of this you'd need a aggressive cam or turbo, and better fuel and spark. sorry guys these aren't honduhs.

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"as flat as an ice skaters boobs." hee hee hee! I like that one.

any ways, those all make sense. I knew that the 12v were newer and prolly better designed, but the airflow and heat buildup hadnt occured to me. makes sense. not that I was planning on testing any of this out on my lil' baby. she's gotta take me to work and back tommorow! (traffic on 401 through Toronto = )

Doesn't really matter when the stock ecu cuts spark at 7200rpm anyways. 4g37 ecu cut it down to 6800 in my experience. There's always degreeing the cam to take advantage of the higher rpm, search for the template that gets posted every once in awhile.

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Had a:
1991 Eagle Summit ES Hatchback - 4g15 12v 5spd
1991 Dodge Colt -4g15 12v 4spd
Have a:
1978 Oldsmobile Cutlass - 468BBO TH350
Round 3:
1990 Dodge Colt-4G63T 5spd