project89

iTrader: (1)

lol u could just go get a 3.1 port the heads install a 260 cam , install a 50 to 60mm turbo run 12 psi of boost. easy 300+ hp and 28-35mpg depending on how well u tune it

Ozz1967

iTrader: (4)

Not to highjack a thread, but everything I've seen is that you lose 20-25% through the drive line with an auto car. Manuals are considerably less. So 300 RWHP would be near 375-400 crank hp. If I'm wrong, I"m wrong but I've not seen any other data to contradict this. If you've got data to prove me wrong, I'd love to see it.

cuisinartvette

maybe his answer was harsh but imo true
No way hes gonna get 30mpg with a gen 1 TPI and 400 or 375chp.
Just wont happen.

OP whats wrong with approaching 20ish hwy is that such a bad thing?

Tom 400 CFI

I think that it depends a LOT on the converter; the looser it is, the more % "loss" you'll see on a chassis dyno. Again, using the C6 as an example, LS2 auto's generally put down ~340 and LS3's ~370 or so. That is around 15% loss. With a loose, sloppy converter, you'll see less efficiency but I would think most poeple would do a dyno run w/the converter locked for consistancy and more comparable #'s to stick cars. That's what I would do to eliiminate the converter as a variable from the equasion.

Tom 400 CFI

I gotta agree here too.

My truck gets over 20 mpg which is fantastic for a 4wd, fullsized truck. My 'Vette gets over 30 easy and 27-28 commuting to work, which is fantastic for a 300hp fun car.

Driving the truck every day costs me ~$80/week or ~$320/month. That is a lot, and I don't want to pay that much.

'Vette costs me ~$60/week, or ~$240/month. That is a lot too, and I don't want to put that many miles (~440 week just for my work commute) on it, nor do I want to drive it in poor weather.

I did (sort of) what Zaar said. Rather than spending $$$ to eek a few more mpg out of my truck or my 'Vette (which could take year to see a return on), I bought a cheap "Maxi-economizer" -and '80's sh1tbox. For $1k, I got an '88 Integra. Runs awesome, everything works....41mpg so far commuting to work.

http://www.fuelly.com/driver/tom400cfi

This is really the way to go guys, if you want to save money on gas. Buy a beater. Take the stress/load off of using your fun car as a DD, and everything is cheaper; tires, brakes, insurance, etc. I just did front rotors and pads on the Integra for <$50.00. I don't GAF if anything happens to it, Don't care about driving it in any weather..I just don't care! And I LOVE that feeling for my DD/commuter.

I now spend ~40/week or $160/month on commuting gas, and the car will have paid for itself by the end of September (bought it end of March).

Buy a crapper and drive the wee out of it. THen you don't have to care about the economy of your fun car.

Thirdgen89GTA

iTrader: (5)

Just wanna add that since I posted in this thread last I had a trip to Road America.

Its about 160 miles from my house, so a few hours of nearly pure highway or county road cruising with not much stop lights.

I finally installed my T56 trans, so it was no more automatic trans for me.

The car traps 103mph @ 3720lbs race weight. Based on those calcs the engine is making between 310 and 330hp at the flywheel.

On the way up to Elkhart Lake WI I got 32mpg.

On the way back with WI's better gas it eek'd 34mpg.

Thirty FOUR miles per gallon.

With a internally stock B-body LT1 and bolt-ons through a T56 6spd and 3.23 axle.

Hmmmm...

A 5.3L is less displacement, similarly sized camshaft, and better heads. Makes more power than my LT1 did. Behind a T56 it may have been possible to best that number as well.

Cadaver Puncher

iTrader: (1)

Wanna build me a 3.1 bro? lol
I keep finding gremlins in mine. Like the v6 positioning, and the ability to pass up a gas station.
Would be nice to actually be able to embarass a few people with my v6.

m16a2r

I get close to 30mpg on my 1999 formula m6 with 410rwhp, did 360 mile trip on 1 tank of gas 90% freeway driving
ls1 with 5.3 prc heads and 228/228 cam

Zaar

Ok,
lets first get one thing straight and i understand this is a day late and a dollar short but i just found this thread with my name attached ok i see that your one of those magical dreamers so ill explain my reasoning to why i said what i did. most of us here spent thousands of dollars lots of blood sweat and tears into our projects. when a post appears about trying to gain 300 whp and 30mpg i have to say what are you sacrificing to do this? additionally whats the cost involved? do you have deep pockets? i didnt when i obtained my 3rd gen and the economy does not look any better doubt we can achieve all these builds and maneuver what we all wish to have so reality checks in and says cherish and appreciate what we have and maintain our cars as much as we value them if its mpg you want find something that can do it without manipulation of original build. ive been around here too long to play the back and forth game so i do apologize if i struck your nerve speaking out loud. but 9 times out of 10 most do not go with your recommendations nor mock builds. been on this site since 01 before i left for the service then i couldnt utilize my old name for some reason. oh well any direction take it with a grain of salt and understand where i am coming from. thanks

cuisinartvette

Thats the direction Im headed
With a DD truck that avgs around 14 mpg mixed driving and the toy around 5mpg you start noticing ga$

If the general could have gotten 300whp and 30mpg they woulda done it.

Choose a combo that makes sense and get the best tune you can afford and the mpg will be whatever it is.

I understand a long hwy trip and trying to figure optimum mileage but thats rarely the norm for driving.

Maybe GM missed something and got lousy mpg by mistake lol.

Ozz1967

iTrader: (4)

I think, if I had a V6 car, and I had the money, I'd find one of the new V6 motors from a Camaro that gets 300HP and 30mpg, and install it, harness, sensors and all! hehe

Thirdgen89GTA

iTrader: (5)

Wouldn't be 300rwhp, it would be about 245-265hp at the rear wheels at that point.

But the High Feature V6's can make some very good numbers. Heck, the 3900 V6 can make some very good numbers as well naturally aspriated.

Read up at 60degreev6.com. Lots of guys making very good numbers.