Well i have been getting the iroc ready for a car show in texas june 2nd. well last night i went to get gas for the 13.5 to 1 compression big block that i have. vp race fuel 9.00 a gallon put in 10 gallons plus had to buy 2 gas cans 17 each so basicly 130 for 10 gallons of gas. the motor has 590 to the wheels. i have heard good things about 4.8's turboed and same about 5.3's heard 6.0 are expensive to build. and to get close to the same hp mark it would be real expensive. what do you all think ..
the motor maybe gets 6 miles to the gallon. so 130 bucks for about 60 miles. ouch

 

man i hate to see that beauty loose the big block. you posted when i was struggling what to do with my 88 super project last month.

i chose to buy a 91 with a lsx instead of going the big block direction. my main reasoning was gas mileage and street drivability with big output.

gas is expensive let alone race gas.

good luck whichever way you go.

 

But an LS engine making huge amounts of power with some sort of boost isn't doing it on cheap pump gas either. It's hard to make high HP without cubic inches or lots of power adder. If you're going to pump in 15+ psi of boost to make lots of power, you're back to high octane again.

My 454SS gets 8-10 MPG on 87 pump gas but it's still basically stock. My diesel F350 gets around 14. My race car runs on methanol. Sponsor pays for the fuel but it's around $330/barrel (205L). I'll burn 1 - 1-1/2 gallons driving through the pits, 1/4 mile pass then drive back to the pit (approximately 2 miles total)

 

yea i hear ya I like the big block in there around where i live i believe it's the only one. and i have spent alot of time getting it in and looking the wayy i wanted it to not just to get it to run the way it should. like today i will be out there readjusting the rockers cause of solid lifters it has 10 gallons of 110 in it and i did notice a difference the whole time i have had the car i have put 91 with octaine booster in it cause i didn't want race gas just sitting in the tank. but once i went to 110 the motor seems to run much better (smoother) and was much easier to start2 pumps on the pedal and turn the key. and that is cold with no choke . different heads would lower the ratio so i wouldn't have to run the high dollar fuel. but the motor would be alittle milder. who knows what i will do .
leave it alone and do the z28 instead

 

In my opinion, I would just bring the compression in the 468 down to 8.5 - 9.0:1, and fuel inject it. Sounds costly, but it isn't if your a good welder, or at least know one. Could always slap a turbo onto it too if you want more power, and with a turbo you can lean out your tune under vacuum; idle and early part throttle, then richen it when it transitions into boost. You'd be surprised by how much mpg you'll be getting with that 468 when your out of boost, and even more surprised at how much power you'll be making during boost. My two cents...

 

To add to the good advice above....what can you get for your big block if you were to sell it? Probably not much. How many gallons of fuel can you buy for the same cost of the swap to lsx + turbo?
As cool as they are, lsx swaps seem to get rather expensive and out of hand pretty quickly.
In the end, does it make sense to spend $2 to save $1?

 

Damn $130 per tank!!!

Have you considered running E85 fuel?

I'm biased but love the MPG and street manners of an LSx

LSx + Turbo + E85= 800rwhp or 600-700rwhp on 93 octane

20+ MPG

Check this out:

http://www.unleashed-performance.com...bo-c5-project/

 

$130.00 per tank nope 130.00 for 10 gallons and 2- 5 gallon gas cans
and it might get 4 miles to the gallon. now thats the ouch

 

Turbo LS can make more than what you currently have on pump gas. Local guy has a twin turbo 6.0L in a 1979 zephyr, makes 600+ RWHP on his pump gas low boost tune. If he cranks the boost and puts race gas in it, 1000+RWHP, car runs consistent 8.40's at 4000ft corrected...

 

You should at least look into E85 before you go through all the trouble of a new combo. You'll lose a little power, but E85 is MUUUUUCH cheaper, and it LOVES high compression.

 

what is needed for e85 it doesn't like rubber hoses if i am not mistaken . but that is all a mute point there is no e85 stations around in ga as far as i know but i think i might leave it alone tho after teh car show the looks and interest in it and of course teh sound during the burn out contest it was sweet

 

I can get E85 right up the road, but Im in Macon. Macon is hardly a thriving metropolis, and it's not available all over the place around here, but there's a Chevron right by the interstate that has it.

Our cars do fine with E85, our fuel systems are perfectly capable of dealing with it. E85 is nowhere near as hard on fuel system components as methanol is, and that's where a lot of the misconceptions are. Regular pump gas is 10-15 percent ethanol to begin with these days.

I suggest you look into this thread in the carb forum about e85. You may be able to make your current carb work, but the e85 carbs are a lot better. Air bleeds and calibrations are pretty different between gas/ethanol due to the differences in stoichiometric ratios. Its more than just rejetting. But if you use quality fuel line , it's just a matter of getting an ethanol carb and tuning it just like you would gasoline.

Beyond that, e85 formulations change with the seasons, so you may have to get some testing kits to see what your e85 actually IS each time you fill up, and you may have to slightly tweak the tune... Maybe buy it in bulk batches... still a lot cheaper/easier than race gas.

And yeah, that's a bit of hassle/work, but in theory you could have a summer jetting and a winter jetting for each season's blend, and even with that and a new carb, it's a WHOLE lot easier than building a whole new engine. Traditionally ethanol means a drop in power, but that's why ethanol loves high compression. Very high effective octane and you get back a lot of that power you lose by trying to run it in a vehicle with compression ratios meant for pump gas.

Anyway, like I said, doesn't hurt to do a little research.

http://e85vehicles.com/e85-stations.html

There's a station in Lawrenceville and several in the atlanta metro area. At least a dozen by what I see on the map.

I dont know what the compression "limit" on ethanol is, but that's why I say do a little research first, couldn't hurt, and ethanol is hardly unavailable if you know where to look.

And personally, Im pretty convinced that in the next 20-40 years, ethanol will be the main way we can keep these things running. Oil wont last forever, and we'll have bigger problems to deal with than just keeping our hot rods running, but I think ethanol will be the long term answer. Not for the general populace for commuting... but it has a lot of advantages from our point of view.

 

I am sure you get asked all the time but I need to know how did you keep a T5 alive behind a 468?

 

Well i am not a young kids so hot ******* the car everytime i was in it i didn't do and i was also aware that the t-5 wouldn't handle the power well so bringing it up to 3 grand and dumping the clutch was out of the question. I ave since switched it back to a automatic. I went to a th350. it's much easier now the t-5 setup was hard to setup and never really worked right I had bought the scattershield and used teh hydralic master and slave cylinders but with the 11 inch clutch i don't think it had enough force to disengage the clutch fully i bleed it many times readjusted the pivot ball many times and it never really wanted to disengage not to mention the headers dumped right at the slave cyclinder so after running a few the pressure would drop because of the heat from the headers. i thought about going to a howel hydralic throwout bearing but doing a automatic was easier.