when i was 15 i had my moped with a 60-65mph top speed and still getting 200 miles on a 2 gallon tank..

 

Having other alternatives is one way to save gas

 

For highly efficient heads, it's hard to beat Vortecs, but you have to change manifolds, and that gets expensive.

Also, no matter what heads you choose, look for a cam with similar specs and most importantly lobe centers to the LS-1. A very good compromise between power and mileage.

The LT-4 is rated the same for Highway mileage as the LT-1, but if I remember right, it's an MPG or two down in city driving. It's been years since I saw an LT-4 window sticker, and that was on a Corvette, so I might be FOS (Full of S&#t)

Troy
So Cal

 

Now we're getting somewhere, What about a LT4 cam in this project? Isn't there a HOT cam too? Or IS the LT4 the "Hot-cam"?

Yeah, I know them vortecs is good, but to shave a little weight I thought of fastburns, but they supposedly dont bolt op to LT1-4 intake.

Maybe going LT4 altogether would be the best choice.. the whole package, heads, cam and roller rockers.. but at that point it would probably be easiest all together just buying a used complete engine. I thought LT1 heads didn't bolt up to a gen 1 block..

 

There is the LT4 cam that was found in the production LT4 models and then there is the GM hot cam that is an upgrade to replace any base LT1 or LT4 cam. The LT4 technically bolt up to a gen I block but you have to do some magor work to use those heads. The main thing is that you have to completely change the way the coolant goes through them. They are reverse cooling heads that are not the same asany Gen I head or block. if you want to go the LT1 route just buy an LT1 and mod that. You can make just as much power with an LT1 as you can with an LT4.

 

Fastburn heads will bolt up to the gen1 block, but they have an intake runner of over 200cc IIRC.
If you want to save $ mod some LT1 heads to fit the gen1.
If you want to use the gen1 block, but don't want to do the labor of modding LT1 heads, then aftermarket heads are what you'll probably want. But in either case you'd have to mod an LT1 intake to make it work, since the miniram is out of the picture. (see last post for more on that)
An LT1 motor has it all in one package. In stock form the LT1 would give you the best fuel efficiency. Add a larger cam to that and fuel consumption will go up slightly, and you'll get more power up top with that also.

 

Okey, so LT1 heads don't bolt up to gen1 block. allright, then we're back to fastburn heads who will accept LT! intake with a conversion which cost's about $200. Hope the ports line up good though.

 

I don't think fastburn heads would be a good choice if fuel economy is an issue, with those 210cc intake ports.

 

OKey.... I thought efficiency was the whole purpose with those... What would you reccomend then?

 

The trouble is, the factory never produced any really good heads til the gen2 sbc came along.
There are the L-98 heads which will bolt on, but the LT1s are better. I've looked at some tests where the vortecs outperformed the L-98s by about 20hp.
The options are: modded LT1 or LT4, and an LT1 or LT4 intake modded to work with gen1.
L98 heads, or aftermarket heads.
Something I'm considering is buying a totalled LT1 Fbody, and swapping the engine, trans and ecm in.
L98 heads with some major chamber deshrouding and a modded TPI is also a possibility. But I think an LT1 engine/ T-56 trans swap sounds better.
The best bargain is the gen1 with modded LT1 heads + intake tho.

 

I just want to point out that horsepower is directly related to fuel consumption, a point some of you seem to understand, and some of you are missing.

the most fuel per revolution is being used in your peak torque area during WOT, this is also where your engine is MOST fuel efficient (BSFC). the most fuel OVERALL is being used at your peak horsepower during WOT, this is where your engine is doing the most possible work in the least amount of time, but less work overall per revolution.

when your on the highway factors like drag coefficient play a much larger role in determining fuel economy than friction loss from a wider piston ring. besides drag, driveline loss is one of the big MPG destroyers. just by chaning to an aluminum driveshaft and a smaller torque converter (9.5" from 12") you can expect some very noticable improvments in fuel economy...

steeper gears may raise your RPM (and thus friction loss during cruise) requireing the engine to make more power to sustain itself AND the car, but the engine does not need to put any EXTRA horsepower (and therefore FUEL) to the GROUND to keep the car moving, so theoretically we can have any cruise RPM we want (8,000 or 1,000) and get the same fuel economy, although this is not possible due to the nature of higher RPMS requireing more power from the engine due to friction and pumping loss, AS WELL as the fact that the breathing characteristics change as the engine REVS higher, things like cam overlap can have more of an effect at the higher RPM and dump more fuel out the exhaust because of scavenging, something you WANT during WOT but DONT want during a sunny highway cruise.

in fact there are times that a higher stall converter / steeper gear (3.73) actually HELP fuel economy, if your engine is setup more for a higher peak VE (BSFC) and a higher RPM load capacity your engine will do less "Work" (horsepower = fuel) in its powerband therefore requiring less fuel while doing it. going from my stock 12" converter to a 3000 stall 9.5" converter increased MY fuel economy, so I know this to be truth, I didnt just read it somewhere.

 

How much would you think one could get those LT1 heads for? And they are iron right? In the summit catalouge they have a complete LT4 topend (cam, head,rockers, intake) for $2289 , but then it's aluminum heads.

What exactly is it one has to modify on the heads to make them mount on a gen 1 block? The thing about the reverse cooling I don't see one could do very much about that..


Okey Kingtal0n, we have been through most of that already. It's the engine parts we're after here especially heads cam, intake, well rods pistons crank and everything else too I guess.

The magazines build engines which have so so much power, but never say anything about's its milage on everyday driving. If they say anything at all, it usually is whether or not it can be run on regular fuel, but not if you need to tow a tanker behind or not.

 

https://www.thirdgen.org/techbb2/sho...ight=LT1+heads

 

Check some of the links on the LT1intake.com site

http://www.lt1intake.com/services.htm

http://www.malcams.com/legacy/misc/headflow.htm