Where is the best place to buy a new or used LS7? Anyt
hing in particular to watch out for?

Well if you want a new one this bunch will sell you one.....

http://www.chevroletperformance.com/P ... wcase_detail.jsp?engine=2


For used I would start on EBay or google used LS7's....

Are you going to drop an LS7 in the '81 now?

I am thinking about it. Money, of course, is always the issue. I was passing a "shelby" on the freeway and he hit it and I hit it and he was pulling away. That's not acceptable! It said "shelby" below the door and he had a hood scoop but no racing strips. What would he have been running? It was a recent vintage and a stick I am sure. An auto, like I run, is less RWHP than a stick with the same engine so I am behind the 8 ball right off.

Yes. The manual will help you on the roll... pumping loss of an auto will cause you to lose power.

However, any newer Shelby is pushing out over 400hp. Period. End of story. And once you take their weight into consideration (and momentum has taken over), it sorta washes... meaning the weight advantage you have.

I remember your car now... the LS3 conversion.

If you want more power, don't bother with an LS7.

Do a manual conversion (it's a C3, right?) and add a supercharger.

At that point, you will be smoking anything in a straight line.

Yeah one of these will take care of any snake problems...


http://www.jegs.com/p/Edelbrock/Edelb ... Corvette/1287709/10002/-1

If you're intent on getting a big displacement naturally aspirated LSx motor, I know Scoggin Dickey has a LSX 454 they sell for around 60-70% of what a new LS7 costs....has more power too and utilizes the LS7 cylinder head.

Man, it's sooooo easy to get power out of an LS3 without supercharing or switching to an LS7. Seems like the hardest way to add less than 70 Hp.

Cam and head work would do it for much less.

If you've made up your mind and you're selling an LS3 let me know...

In upgrading the power of the LS3; What heads would you put on and does the "hot cam" add hp and tq along the whole rpm range? Someone told me that the cam lot tq at the lower rpms and what would all that do to gas mileage? Like a couple of miles to the gallon or?

Let's approach this from a more systematic perspective, than just throwing parts at it.

I used to race RC cars... and this kid I raced against was always getting beat... and he always wanted to get faster parts. Until I talked to him... and said, "look kiddo, you have fast enough parts and you can't control them. Learn to drive what you have, make that go faster and don't wreck it. Then you can go even faster."

His car would not hook up at all... I worked with him, taught him my battery conditioning tricks, motor tuning and tweaking, helped him rebuild his car right - no ugly fixes, no bad solder joints, no miss-matched screws... it was RIGHT. And then helped him with the setup (pan car oval racing is very aero dependent... you have no idea how badly a poorly raked body will make a car handle!!). And you know something? He got faster. And he finished races. Paying attention to details... with that said...

You already have an engine pushing out 430hp. That's a lot. In a car that weighs about 3500 lbs. Not bad.

Better than the power to weight ratio on that Stang.

Now, if you are getting that 430hp (and IIRC, you were having issues with the tune), but sure the tune is right.

Next, the drive line. What rear gears are you running? Automatic, yes, but what kind? Is it a newer 4L60E or is it an old school TH400? As bullet proof as the TH400 is, without a locking converter and an overdrive, you are losing over 20% of the engines power in driveline slop.

All of this is about making what you have work together better...

I suggested a manual trans... I still do. TKO makes a nice 5 conversion for the C3.

http://www.keislerauto.com/Keisler_Auto/Keisler_Engineering.html

Also available would be retrofitting a T56 6spd or a cheaper T5 5spd. But with the power you are making a T56 would be wiser.

You can get a used T56 for chump change, really... From what I have seen on ebay, figure $900 to $1500... there are some hard core rebuilds by Hurst for $3k.

http://temp.corvetteforum.net/c3/gwhite75/index.htm

The link above looks REAL interesting. I don't know what else is needed when doing this with an LSx motor... Perhaps a different bell housing? I would think if you got a bell housing from a 98-02 Fbody, you would be on target.

If it was my car, that's where I would spend my money first:

* Make damned sure the tune is RIGHT
* Improve what I have with a better trans and gears

The other upside? MPG. You will get much better highway MPG with this setup. Depending on your current rear gear, you may want to go up there, too... I suspect they were softly geared, thinking 3.07:1 or so, I would want 3.55:1 or 3.73:1 for the 6spd. 6th on a stock T56 is .50 overdrive! You would need to be doing nearly 100 to take advantage of it with a 3.07 gear!!

A car is more than an assemblage of parts, it should be a well planned and prepared for system. So that all pieces work together for a common goal.

What good is 800hp if you can't get it to the ground? When you lose 200hp because the torque converter never locks up, or locks up at the wrong time. What's the point? Wasted money... that's the point.

The more I think about it the more I think you are absolutely right!I really do have some potential with my set up. The car only weighs, empty with no driver or gas, 3020 lbs! I just weighed it yesterday. I have been ripping weight out of it for years and I am finally about where I want to be. I suspect the tune isn't right yet and there is something wrong with the trany. I don't think it is locking up all the time (because it revs and I don't go anywhere fast so to speak). It is a 4L70E. I put a 373 rear end in it all ready. I live out in the boonies in Montana and I need to find a good shop with a dyno to go over my engine tune and trany shift/lockup etc. This makes much more sense than pouring tons of money I basically don't have into it like the young man you helped out wanted to in the racing situation. I know the 5 speed stick fits right in but the 6 speed isn't an easy fit so they tell me. Would my Dana 44 rear end stand up to the shock of a stick with 430 hp? Anyway thanks for lining me out on this. I have a set of Wilwood brake calipers and a brake reservoir to install this winter and that will put me under 3000 lbs! I believe the stangs weigh in at about 3800 lbs. The math is in my favor but only if the engine and trany are performing as they should.

Yea! We are on the same page!

The links I gave show how a T56 goes in... easy? meh... can't help ya there.

Tune? I am sure that can be fixed with a handheld device, because the PCM for the LS3 is programmable. You can come real close with just a good stock tune. The engine isn't modded, right?

As for the D44... uh, yea. They will more than take it. The D44 is highly desirable in the C4.

Now, do you have the later aluminum case or the older iron unit? In 1979 or 80, they swapped over to aluminum cases and composite rear springs. Saved a bundle of weight.

And yes, the stang is one heavy pig! 3800 is for the V6!!! The V8 adds 200+!!!

I have fun with mustangs and challengers,but some of those goofy looking rice burners have surprised me,dam A.W.D. But cam and heads/intake never fails.

neither does optimizing what you have.

If the tune is off, what's the point in adding more stuff if it only makes it worse? What if the drive line isn't matched to this 8000 RPM screamer? You lose... period...

This is why a good driver in a properly prepared car can beat a bad driver in a more powerful car.

I know money is an issue.But look at mast motorsport.I wish i had their ls7 but 16k for 667 hp.I just spent 8500 in parts on my ls7 without any lower end upgrades.Not to mention labor costs.If i had their motor i could consider forced induction.And could of sold my stock ls7 at 7000 mi.Dam.

Before you go any nuttier on that LS7, be sure to upgrade the oiling system... the word on the street is that there are some weaknesses that need to be addressed...

just say'n...

My diff is an aluminum. First year. I did replace the iron rear spring with a fiberglass one. I don't think my D 44 is the same that went on into all the C4s however. There are some parts that are beefier and weaker compared to the iron units I believe. I did put the 1350 u joints in the half shafts and a C4 carrier too. My bottom end will really go but it's the top end that seems kind of dead to me. And that's where I was, at 78 mph, when the Shelby pulled away from me. But I will get it retuned on a dyno and see what that gets me. Plus the trany tune too.

If you are losing performance at the top end, that isn't good.

the torque converter may not be locking right... I still think a 6spd manual conversion is the best option.

What gearing are you running again?

I am running a 4L70E with aluminum (read light) drive and half shafts and a 373 diff. Again, I only weigh 3000 lbs. If he was 500 hp at about 3800 lbs; I should have taken him. I think the trany is slipping and not locking up a lot. I do think a 5 or 6 speed would be a good addition. I am getting tired of automatics. They do what THEY want to do. With a stick; you make it do what YOU want to do.

4L70? Never heard of that one.. 4L60... 4L65... 4L80 and 85... but a 4L70?

I agree... convert to a built T56. You will be happy.

And yes, with the weight advantage, he never shoulda been close.