LS1 vs zz4 or 383

[milo30]

Got a question for the guys who have made the swaps. I'm still deciding on what engine I am going to go to in my 78. I want alot more HP than I have right now. Any of these will provide it. I also want fuel economy. I know that most of that will depend on the rear end and an overdrive which I am planning to do anyway.

My question is, using same rearend and overdrive tranny, what kind of difference is there from the engines as far as the gas mileage goes?

That said, let me clarify the question a little more.

1. I know the price difference on the engines and how the zz4 could have the extras for more HP and still be cheaper than LS1.

2. I know that it might be months or years to recoop the savings in fuel prices. My theory is, I'll only have the money to do this once. The money I didn't put in would be spent elsewhere so for me I want to save the money on fillups. In real life that is where I will see the difference instead of the BIG picture of recooping the cost.

3. I know that how the car is driven will make a difference.

For the sake of argument here, let's say the economy as a daily driver and you don't put your foot in it MUCH.

While I am at it why not throw in one more question... LS1 with carb. instead of EFI.

 

[Koop]

The ZZ383 with 3.08 rear and a Turbo 400 gets crap for mileage, where my 350's were pretty decent on MPG with the same trans and rear end.

I hope that helps!

 

[Tom Bryant]

The LS1 will be the most involved swap and the most pricey but used good ones are available. Highway MPG over 30 is common on these cars with the efi. The carb mpg would be somewhat less but easier to install. If you installed a stock LS1 with an overdrive trans and the same gearing that a C5 has you should get upper 20s on the highway at least. This would be hard to do with the old small block.

As for making power there have been several articles on the 6.0 LS series truck engine where just a few mods put it way over 450 or 500 horse. These LS engines seem to be very easy to make big numbers with. Lots of 6.0s in the wrecking yards now too.

Tom

 

[Koop]

My Dad has a '99 Vette with an LS1, I've used the car a ton and 30 MPG highway is real and normal. I own a LS6 Cadillac and the MPG is no where near as good at 13 city and 19 highway. If you do go with an LS motor, the LS1 will likely produce the best MPG and there are tons of mods available for them. I've heard the LS2 gets better MPG than the LS6 as well.

Good luck.

 

[milo30]

LS1

That was what I figured that I was going to hear. Right now my RPMs are crazy at 70 MPH and it will pop out of 2nd gear when you let off the gas. I would have to have the tranny rebuilt and I don't see any reason to put the money into it when I can go to OD and save the wear and tear on the engine as well as for economy. If I do that, I might as well go ahead and step up to the LS1 or 2 then and get a little more MPG. I figure the LS1 will hold up better than a ZZ4 anyway. I am assuming also that there will be a pretty big difference in MPG on the LS1 between EFI and carb also.


Thanks for all the input. I need to run some numbers now and see the price difference. I may have a source for a slightly used LS2 for a decent price. I'm working on that right now...possibly getting it and swapping out the cam and heads.

 

[Koop]

Crazy RPM's at 70MPH? What rear end is in that car?

I have no idea if this will work in a Vette, but the price sure is right!

http://www.cadillacforums.com/cadillac-classifieds/showproduct.php?product=3453

New in the box for $1,300!

 

[milo30]

RPMS

Well, probably my RPMs aren't that far from normal....just seems that way to me because my LT4 cruised 70 at something like 1200. I always worried about the 78 on the highway because it was so much higher since there was no OD. Kind of like trying to get used to the hot temp the C4 ran at always worried me.

I'm still doing some shopping. Saw a 99 camaro LS1 complete with computer, wiring harness, 6 sp tranny and a few more things for 2600.00. Going to take my time researching what I want and get it right the first time. It's been sitting 3 years so no need to get into too much of a rush now.

 

[patsnitrovette]

Out of every swap ive done with my vette,383,327,360,406 and last motor 360 tuned port injection,sportsman 2 heads zz4 roller cam,the ls1 swap is the best so far ill never go back .Ive done all the work myself, so its saved me a ton of money i have $1800 into the whole swap including building the ls1 from a bare block.Theres nothing like hearing a ls1 through sidepipes either,and with my 700r4 and 3.70 gears it just cruises around.And whats really nice is i hook up my laptop to it and cruise down the road datalogging all my info,stop on the side o f th road make some changes ,timing fuel ,anything i want.reload that back in the pcm and try it again.Efilive is my friend.

Now that ive driven it for a few years now ill be pulling the body off and redoing entire car again and making changes to the ls1,cam swap and head work.

 

[milo30]

I'm about 85% leaning towards an LS1 and tranny swap. How did you do it all for $1800? I figured the block and buildup would cost more than that. I am looking at some used ones out of a camaro so I can get the tranny and everything else. I can get almost get everything that I need minus the radiator for around 2500. I am thinking get something like this, put a cam and better heads on it and I'll be pretty happy.

Part of me wants to stick with a manual tranny but my head keeps telling me go auto (and my wife also). You happy with that tranny?

 

[patsnitrovette]

I really wanted to do the swap on a budget build,i had been seing people spending 5000 or so on swapping ls1's.I searhced for the best deals.Ls1tech.com has tons of good deals,ebay,corvette forum.com in the c5 parts for sale section.I picked up a 99 camaro wiring harness and modified to work saved me $500 from buying an aftermarket harness.There easy to change and make work.I got motor m ount adapters from vettedan,i used my hooker sidepoipes and modified them to mate to new ls1 exhaust flanges.I used my 700r4 i already had bought a crank adapter and the 6 longer bolts plus a new c5 flexplate and bolted right to my 700r4 convertor.Theres plenty of deals out there you just got to look.Also got a ls6 intake with ls6 injectors and fuel rail for $85 thats a smokin deal.
As far as the tranny yes i love the low first gear especially with 3.70 gears,im gone to go with 4.10's next.And as far as programming the pcm for 700r4 you change it to run as a 6 speed trans instead.