408ci Gas Mileage???
Thread Starter
TECH Resident
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408ci Gas Mileage??? Hey guys, I'm on the fence about forging my internals + super charger + spray and just getting a 408 + spray. I'm hoping for around 500 HP without the nitrous and 800+ with nitrous. What'll really make me choose between the two setups is gas mileage. So, those of you who have 408s, or have friends with 408s, how's the mileage?
Thanks!
-somebody
Thanks!
-somebody
I get about 13 average, about 75% in town. That's with driving fairly easy. I've seen as high as 22mpg cruising at 65-70mph. And as low as 9mpg when doing only very short trips at a time. At a constant 110mph for about 1 1/2 hours I got 16mpg. I think the spray option will get you better mileage.
If mileage is as important as power, go with a forged 346 and put a turbo on it. Out of boost, your mileage will rival a naturally aspirated 346 as the turbo doesn't have the parasitic losses (mileage sapping drag) of a supercharger. A hair dryer or two can easily get you over 800 rwhp with a forged 346.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
TECH Senior Member
Joined: Mar 2004
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From: BFE
Who cares??
If gas consumption is an issue, do not mod, sell the V8 and get a tiny 4 banger.
You want power? Then a simple rule is "when it is empty, fill it up !!"
But Patrick G is right. Hair drier motor, intercooled has shown best fuel efficiency for power produced.
If gas consumption is an issue, do not mod, sell the V8 and get a tiny 4 banger.
You want power? Then a simple rule is "when it is empty, fill it up !!"
But Patrick G is right. Hair drier motor, intercooled has shown best fuel efficiency for power produced.
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Thread Starter
TECH Resident
Joined: Dec 2004
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Originally Posted by PREDATOR-Z
Who cares??
If gas consumption is an issue, do not mod, sell the V8 and get a tiny 4 banger.
If gas consumption is an issue, do not mod, sell the V8 and get a tiny 4 banger.
I'm just not sure I want to get something that could have possibly only yeilded me 5-10 highway mpg. Cruising would be pointless and annoying if I have to fill up every half an hour. 
Not everyone wants a track-only car. I can't live my life a quarter mile at a time! [/Vin Diesel]Thanks everyone else for your replies. I may just get that Lunati 347 kit.
-somebody
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TECH Fanatic
Joined: Oct 2002
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From: Dallas, North Mexico
Originally Posted by Patrick G
If mileage is as important as power, go with a forged 346 and put a turbo on it. Out of boost, your mileage will rival a naturally aspirated 346 as the turbo doesn't have the parasitic losses (mileage sapping drag) of a supercharger. A hair dryer or two can easily get you over 800 rwhp with a forged 346.
you are clearly dropping BIG bucks on this engine. why wear it out on in traffic on the way to work.
$5000 for a nice civic to and from work will spare this engine, gas milage and a slew of headaches.
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
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From: BFE
Originally Posted by Somebody09
Obviously I care. I made the post did I not? And I thought a few bolt-ons out there actually helped with gas mileage... I'm just not sure I want to get something that could have possibly only yeilded me 5-10 highway mpg. Cruising would be pointless and annoying if I have to fill up every half an hour. Not everyone wants a track-only car. I can't live my life a quarter mile at a time! [/Vin Diesel]
Thanks everyone else for your replies. I may just get that Lunati 347 kit.
-somebody
I'm just not sure I want to get something that could have possibly only yeilded me 5-10 highway mpg. Cruising would be pointless and annoying if I have to fill up every half an hour. Not everyone wants a track-only car. I can't live my life a quarter mile at a time! [/Vin Diesel]Thanks everyone else for your replies. I may just get that Lunati 347 kit.
-somebody
Those 2 do not go hand in hand.
If you do not want a track car, stay away from strokers, they are pointless on the street (can never hook).
If you want decent mileage and power, then go with like a stock cubed, AFR headed cammed combo. Still decent at cruising and wicked at WOT.
