Jay-SS

Not sure exactly how feasible this is but here goes. Currently I have 430ish rwhp DD LS1 SS that kinda bugs me sometimes. It has a 3200 stalled A4, 3.73's, and the exaust dumps under the center console.

With my current set up and driving habits I see roughly 10-15 MPG on average. Short distances, low speed limits, 3200 stall, it just devours fuel. Its dramatically better on the highway, but it rarely sees the highway. I'm swapping in a 6-speed so that should alleviate that problem by quite a lot.

So lets talk reliable and well-mannered 600rwhp possibilities. I plan on dropping down to 3.55 gears and doing an out the back TD exaust. As for the power... I know N/A is pretty out of the picture, especially out of an LS1 with those standards. I reaaaly hate the idea of turbo lag so im pretty narrowed down to superchargers.

Moving on, how concievable is a comfortable, supercharged, decent MPG-achieving LS1 making 550-600 rwhp? I'm assuming its a stretch, but wanted some forum input.

I'm also considering swapping in an LS3 with the intent of the same goals, any thoughts on this?

Finally, if I cant get what I want out of either of those options, i'm even considering saving up a little to swap in the lsx454 and s/c that. That should easily hit my rwhp goals but then i come back to the, is that conceivable for a comfortable, good mpg, DD.

Anyways, thanks for any input! Cya !

NVUSZ28

iTrader: (5)

You're gunna up the HP and see MPG drop. And you wouldn't pick up much more MPG gains over a M6 and a built motor. 1-3, at best.

Now Turbo's are your way to go if you want to keep MPG in mind, you can have little boost on lower RPM, without guzzling fuel. a Supercharger will be "in play" 100% of the time.

BashamWS6

iTrader: (8)

if you drive a 6 speed like a normal human being you will see gains over an auto. ESPECIALLY A STALLED AUTO.i get 25 mpg with 50/50 highway/city driving while my friend gets 17mpg 80/20 highway/city

no turbo. turbo needs high rpms to be productive.

you want to achieve 20mpg?
get a m6 built by tick to handle the torque
a clutch that is streetable and to hold the power. i would get a spec 3 and not monster if i could do it again
a 9" or fab9 also to hold the power
UMI, BMR, or Spohn suspension (lcas, lca rlbs, t/as, sfcs, shocks, even upper/lower a arms, k member)
Nittos or other DRs to keep that power connected.

then you need a built and forged 5.7L ls1 to handle the power and keep decent mpg. 6.0L heads to get th compression right and a cam that is boost friendly not a donkey dick big *** cam that you will hate.

255 LPH fuel pump, 60lb injectors, high pressure oil pump, high pressure water pump, and 160 t stat and fan switch to keep it cool

then get a D1SC or F1 Procharger with FMIC and Alkymeth kit

thats if you wanna do it right and be streetable

garygnu

a nice 408 or bigger with l92,or ls3 heads mite make close to 550.

TheLS1Lover

Wrong, a properly sized Turbo will spool in the low RPM range and stay out of boost when your foot is not it the gas pedal.

Also wrong, well not completely. 317 heads are used to lower compression on a STOCK bottom end (11:1 CR) LS1. If he is forging the motor he can run dished pistons, no need for 317 heads. Ported stock heads will suffice.

Better add another 255LPH pump in that equation. One will not due.

A 347, TC76 Turbo, Built T56 or TR6060, 9", Suspension, and supporting mods and your their.

Also do you have E85 readily accessible in your area?

Sladester2

iTrader: (1)

Put 4:10s in that sucker. 6th gear will still be running low RPMs on the highway

BashamWS6

iTrader: (8)

oh, well i just have always heard prochargers were better than turbos.. idk tho

Sladester2

iTrader: (1)

I would rather have a supercharger for a daily driver anyday.

409CISecondGen

iTrader: (2)

Smaller displacement, iron block, turbo car sounds like it fits your goal.

How about a forged 5.3 iron block with a large turbo. A smaller displacement will give you great gas mileage and the turbo won't spool (and thus you won't be wasting fuel) until you are in the upper RPM's. The forged rotating assembly in the iron block will handle whatever you throw at it, so you can run lots of boost and make lots of power.

30th t/a

iTrader: (51)

Sell your stock LS1. Buy a LQ4 or LQ9 6.0, these engines in STOCK form are very impressive with boost. And they cost any where from $1000-$2000 depending on the mileage. Install a set of 918 springs & LS6 cam. Throw 8-12psi at it with a Turbo or Procharger and you'll make 550-600. I just sold my LS1 and im looking for a LQ9 right now to go with my twin turbo kit. The bigger cubed 6.0 with its 10:1 compression and a smaller sized turbo will make 550-600 and spool insanely fast.

I disagree with the post above. The smaller 5.3 with a large turbo will feel sluggish when out of boost. Been there done that, SUCKED.
Bigger cubes, more compression and a smaller turbo will still give you more throttle response & power when your not in boost and will make full boost earlier in the rpm range. It be alot more fun on the street.

409CISecondGen

iTrader: (2)

In my opinion, thats what you would want to maximize gas mileage. The larger engine will spool sooner and need more fuel, plus 5.3 blocks are dirt cheap and all that extra cylinder wall will help with boost.

Also, I wouldn't use E85. While it may have a higher octane, it also burns way faster and your gas mileage will suffer more than the price of E85 can offset. Plus there are other reasons like the fact that the government subsidizes it, the much larger fuel system needed, and its corrosive properties. Anyways E85 rant off lol.

BashamWS6

iTrader: (8)

Lighten up the weight too. Less weigh requires less power to move it.

Bazman

Turbo vs blower power delivery is one of preference. I have a custom STS turbo right out the back and I don't notice turbo lag with the auto and 2800 stall. It's perfect for DD for me. Boost comes in around 1800rpm and I would not want it any earlier as it'd just wheelspin.

I have my DD so it can be feathered in the wet and as it sits I could throw the keys to my partner on a rainy day and not worry. Would not do that with a supercharger. BTW my LS1 is crisp, poke the throttle and it'll rpm as quick as a blower car, just won't hit boost as early and that's how I want it.

As for mpg - turbo has more potential than a blower due to less parasitic hp loss at cruise. My car is a 4 door auto sedan weighing 3700lbs empty with a 222/226 cam yet still managed 25.8mpg on a highway trip recently. It only makes 450rwhp but that is because I only run 6psi boost on the stock bottom end. Same setup will easily pull 600rwhp and more when I build up an LS2 or 3 - the entire system had that in mind when I did it as the old LS1 has passed 100k miles now - yet is still mint ;-)

Transamman25

iTrader: (1)

I would say run a 6.0 with twin GT35 turbos... Lag? You would have to look for it, Your power band would easily be a 1800-5500 rpm band.

As for upping power and improving fuel economy, It's simply impossible (the more air, the more fuel is required) Yes 600rwhp would easily be attained, and very driveable.

409CISecondGen

iTrader: (2)

small displacement with lag makes it possible: No extra fuel in the lower rpm band

garygnu

the proper cam will make a turbo work like a dream and do everything you want from it.take your time and plan this build out and it will work .

Jay-SS

Thanks for the input everyone. As for the MPG I was counting on the swap from an stall to an m6 would almost single-handed take care of that, not to mention dropping the gears a little. I just wanted to find a way to make it not drop back to where it was if I throw more power at it.

I'm surprised at how many people are suggesting staying with smaller cubes. Here's what I hate from the lag idea. Right now I have the 3200 stall. It's simple things like trying to overtake ms. daisy. so I move over and give it a part throttle hit. The stall doesnt lock because I didnt get it over 3200 rpm yet so i'm slowly crawling past her while the exaust is just roaring. Yes I could just give it more throttle and lock it up but i'm not trying to blow her doors off and I look like a jackass for going sounding like i'm going WOT every time I just wanna pass or leave a stoplight. I've actually had people tell me at stoplights that somthing is wrong with my transmission. lol /sigh.

Turbos sounds like they would give me a different type of the same problem. Part throttle hit, and slowly crawling while waiting for spool, just with less noise. That would bug the **** outta me. I've never actually driven a turbo car I'm just going off what i've gathered from watching and reading. Superchargers have that "always-on" feel for instance response which is why it sounds like the better option, unless it destroys my MPG.

TheLS1Lover

With a properly sized turbo and motor combination you WILL NOT notice the lag. I suggest calling Jose at Forced Inductions after you get a good motor spec'd out. More than likely he will recommend a TC76/8. Those things will make 550-600rwhp and spool in the 3000 range, seriously how long does it take to hit 3000RPM? Like 2 seconds. Plus you can always brake boost

30th t/a

iTrader: (51)

I was in this same situation. Ive had 2 different twin turbo setups. Both were a forged 347cid, both 8:5.1CR. One a 6 speed and the other a 4L80e with a Yank 3000. When you smash the throttle, there was a few hundredths of a second delay, then a sudden hit of torque & power (which felt insane). But the car was slugglish out of boost.

I rode is a friends car that had a 408cid with an Incon TT kit and there was no lag what so ever. The power came on like a 700rwhp NA car, yet drove like stock. I said Id never go turbo again and was planning on going with a D1SC procharger but I got a deal of a life time on my current TT kit. I couldnt pass it up. So Im hoping with the extra cubes of the 6.0 plus keeping the 10:1 CR, that the car will have more power and a crisp throttle response while out of boost. Im confident that it will.

Jay-SS

I'm interested in how your set up works out. You hit it right on the head, those hundredths of a second of slug/lag is exactly what would irritate me, EVEN IF a second later i'm suffereing from torque induced whiplash. Lemme know how yours turns out and what kind of economy you get out of it when normal driving.