Opinions please, what mpg for 370's or 408's?
05-04-2008, 12:21 PM
#22
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I have been really pleased with the present LS6 cam on the 5.3. I believe I would just like to keep it, though I know it would be a bit milder in the bigger motor...which is fine...I have averaged 30mpg on cruise 65 in the vette with this stock cam.
05-04-2008, 01:29 PM
#24
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Thanks, I greatly value your input. One more thing, would it be worth the hassle to upgrade to stock L92's vs 317's with this setup? I don't have the 317's yet. And for the future, I am planning a 6L90 when it's available as a turn-key swap.
05-04-2008, 01:37 PM
#25
If you aren't going to run more than 10lbs... Run 10:1 
With your FMIC 10psi is a goer at 10:1 (I ran my at 10.1:1 with no FMIC and 12* adv. -- more when I added the meth). It had zero troubles at that CR and that boost level. Plus, then you get better off boost power and torque, plus better mileage.
BUT, if you ever think you're going to turn it up to 15... 9.5:1
With your FMIC 10psi is a goer at 10:1 (I ran my at 10.1:1 with no FMIC and 12* adv. -- more when I added the meth). It had zero troubles at that CR and that boost level. Plus, then you get better off boost power and torque, plus better mileage.BUT, if you ever think you're going to turn it up to 15... 9.5:1
05-04-2008, 01:41 PM
#26
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Can I run more boost on 93 only without meth? How about with meth? Just have to stay safe, not doing this again.
05-04-2008, 01:44 PM
#27
At 10:1, I ran up to 12 psi with meth only. No motor issues (did blow the tranny tho!) and ran out of fuel pump with a single pump. I'd not go past 12 without forged parts.
If you add meth to your FMIC and put some forged parts in the 370, you will be able to run more boost than the 67 can put out efficiently
Oh... and on the gears, we all love these 4.10s for the seat of the pants.... The turbo will LOVE the 3.42s...
If you add meth to your FMIC and put some forged parts in the 370, you will be able to run more boost than the 67 can put out efficiently
Oh... and on the gears, we all love these 4.10s for the seat of the pants.... The turbo will LOVE the 3.42s...
05-04-2008, 01:50 PM
#28
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It's gonna be forged pistons and rods with stock crank I guess. What about the L92's vs 317's...worth it or not for this combo for DD.
05-04-2008, 02:16 PM
#30
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The l92 heads will probably pick up some power over the 317s at 10psi on each. If you run 10 psi on the l92 head and 12 psi on the 317 I think the power output will be similar. You would have to figure in the cost of the l92 intake manifold and 90mm throttle if you don't have these items.