LS6 vs 90/90: H/C 346
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LS6 vs 90/90: H/C 346
so i was talkin to my old man about my plans for my motor and he said the 90/90 i bought will probably kill off my power below 4500 rpm and kill off my vacuum, vs my LS6 intake. here's my setup:
Forged LS6 (346)
AFR 205s
Comp XR281HR (228/230 ~.570 lift, 112 lsa)
LT's, ORY
is my old man just stuck in the 70's, or does his theory hold true for gen III small blocks? i personally think he's dead wrong, and the FAST 90/90 will perform greatly, but I wanted to ask around and see what more educated individuals have to say. thanks.
Forged LS6 (346)
AFR 205s
Comp XR281HR (228/230 ~.570 lift, 112 lsa)
LT's, ORY
is my old man just stuck in the 70's, or does his theory hold true for gen III small blocks? i personally think he's dead wrong, and the FAST 90/90 will perform greatly, but I wanted to ask around and see what more educated individuals have to say. thanks.
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well LS6 is a no brainer, of course it will make power. i don't mind a small sacrifice in low end if the mid and high range power is way better. as long as i have some good ol' american torque, and i can roll around town at 1500 rpm, i'm happy.
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well it's good that i have both intakes, and i'd love to do a back to back dyno comparing the two, but i'm not about to pay full price for two dyno tunes. i thought about tuning it for the 90/90, then just throwing on the LS6 and getting a reading, but that wouldn't be too accurate since it wouldn't be tuned appropriately for it as well.
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You really should have the Fast 90/90 ported or you will be leaving a lot on the table. Many claim to have the know how to port that properly, I would do a little research if you choose that direction. You will make more power everywhere, accelerate faster & better throttle response.
I have a very similar combination to yours & my injectors are the SVO Red Top 30lbs.
Your tuner will need proper data for which ever injectors as well as the ability to make that Fast 90/90 combo drive nicely.
I'm very old school as well & may have disagreed with your old man even back then. The same tuning problems existed back then & very few tuners had ability to make the more aggressive combo's work. I always enjoyed making the serious combinations drive like the stockers, it could be done back then as it can be done today.
The advantage with todays technology is that we can even go more aggressive with even better manners.
I have a very similar combination to yours & my injectors are the SVO Red Top 30lbs.
Your tuner will need proper data for which ever injectors as well as the ability to make that Fast 90/90 combo drive nicely.
I'm very old school as well & may have disagreed with your old man even back then. The same tuning problems existed back then & very few tuners had ability to make the more aggressive combo's work. I always enjoyed making the serious combinations drive like the stockers, it could be done back then as it can be done today.
The advantage with todays technology is that we can even go more aggressive with even better manners.
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This is a topic that has been beat to death, try to help yourself by doing a little digging. I went from the LS6 intake to my own ported fast 85 and gained a ton of power through the entire curve, see for yourself. I didn't just slap the fast on though, I spent around 15 hours porting it and making sure everything lined up properly, which the alignment was very crappy. I also added an underdrive pulley at the same time and I'd guess it was worth 8 hp. Click my signature link for all the details, but it's just a custom 224 cam with unported 243 heads.
Bolts on vs head cam LS6 vs Fast 85 + underdrive
Bolts on vs head cam LS6 vs Fast 85 + underdrive
#17
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Here is why; In the 70s carburetors fueled the engines, carbs require a vacuum signal to pull fuel out of it. So if your carb was way too big it wold kill the low end because the velocity of the air going through the carb at low rpm is low. This is why they had losses in low end when you had a carb that's too big.
Now skip ahead to today, we have EFI with an injector in each cylinder. We don't carry fuel through the intake, which is called a dry intake because it only carries air. We inject fuel directly at the valve near the cylinder. So now what influences too big or too small is only the runner design of the intake manifold. Since the FAST has proven it makes power on everything from stock to wild, the runners are a best design for the street/strip cars. The throttle body is now simply an air bleed to feed the runners. The runners are what create air velocity.
So you could have a 200mm throttle body on the front of a FAST and it wouldn't matter as far as low end power or ability to make power anywhere. It simply feeds air to the 8 runners.
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A FAST 90 or 92, stock or ported should give the same low/midrage power as the ls6 intake but depending on the setup, make a little more power up top. A 102mm would be too big though for 346ci.
Those injectors seem to be overkill though since they are good till 550+rwhp unless you plan on spraying a dry kit.
Those injectors seem to be overkill though since they are good till 550+rwhp unless you plan on spraying a dry kit.
Last edited by camz28arro; 09-04-2010 at 07:25 AM.
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Incorrect, if you read what I just typed "THE RUNNERS" inside the intake determine too big, too small, or just right. The throttle body just has to be able to feed the runners.
Now a 102mm may not be needed to feed a 346ci, but its not too big, my bother runs a 102mm on his 346ci without an issue.Think about this, individual runner intakes have an infinate throttle body and run very well. They also depend on the runner size and shape for RPM range and velocity.
Now a 102mm may not be needed to feed a 346ci, but its not too big, my bother runs a 102mm on his 346ci without an issue.Think about this, individual runner intakes have an infinate throttle body and run very well. They also depend on the runner size and shape for RPM range and velocity.
Last edited by SweetS10V8; 09-04-2010 at 12:55 PM.