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Looking for Advice and Opinions please.
I'm beginning a build of a 454 LS6 tribute motor.
NOM. Original LS5 is long gone anyway.
Goal is as original looking & running as possible, but no need for matching numbers.
Factory alum heads, intake, Holley, factory or LS6 plus type solid cam.
I've much experience with an 11:1 LT1 in a Z28, but not a BB in a Vette. I intend Street use & gas, no racing.
I'd rather run more than 9:1. and I'd rather run headers.
I am concerned about about compression ratio, timing, detonation and heat.
Ideas or Advice?
Last edited by leigh1322; Jun 22, 2018 at 12:05 PM.
Iron or alum Head LS6? They came both ways. The factory alum heads can sometimes be found on Ebay fairly reasonable. OTOH, iron rectangle heads with aluminum paint look like aluminum heads.
Iron or alum Head LS6? They came both ways. The factory alum heads can sometimes be found on Ebay fairly reasonable. OTOH, iron rectangle heads with aluminum paint look like aluminum heads.
Looking for Advice and Opinions please.
I'm beginning a build of a 454 LS6 tribute motor.
NOM. Original LS5 is long gone anyway.
Goal is as original looking & running as possible, but no need for matching numbers.
Factory alum heads, intake, Holley, factory or LS6 plus type solid cam.
I've much experience with an 11:1 LT1 in a Z28, but not a BB in a Vette. I intend Street use & gas, no racing.
I'd rather run more than 9:1. and I'd rather run headers.
I am concerned about about compression ratio, timing, detonation and heat.
Ideas or Advice?
If you go with aluminum heads, I'd likely target 10.5-1 static compression ratio. If you run the oem 71' LS6 solid flat tappet cam, I'm not sure what the DCR would be, but I would guess you would be plenty safe for 93 octane. Just be very accurate on the timing, read plugs and watch for all of the signs.
I'd likely use a light weight piston like a Mahle or Autotec to get your compression where you want it, and have a much better ring pack and less weight to swing around. No one will know its not the 5lb TRW piston. LOL
Good luck on the build... I'm sub'd.
FYI, about 3 years ago we built something similar, it was actually a date code correct, restamped 396/425hp, on that one, we used AutoTec custom pistons and set the compression at 9.8-1 and went to a hyd roller.... It ended up making 441hp through stock exhaust manifolds. (they were dynoed with real headers from the factory)...Runs great, sounds and drives very close to stock and easily spins to the 6500 redline.
leigh1322:
I like the way you think sir, I looked into going this route years and years back. For what it's worth most modern aluminum heads have better quality aluminum and will likely outflow the "074" heads or whichever casting you decide to go with. Price wise they will range anywhere from comparable to twice as much as a set of aftermarket heads depending on what kind of a deal you find. With all of that in mind, I know if it were me I would end up going with the GM heads. There is just something cool to me about having a piece that originally came on some of the most powerful cars to ever grace the streets. I love the fact that you are going with a solid flat tappet, I love solid flat tappet cams. Top that thing off with a nice Holley 850 Double Pumper and you have sharp looking motor under the hood and a ton of power to go with it. Keep us posted!
Last edited by bence13_33; Jun 23, 2018 at 08:18 PM.
Thanks Bence13-33
I know some aftermarket oval ports would probably run stronger mid-range on the street, but it'll have more than enough anyway.
There is just some car show cred to be had with the winters snowflake, and a factory "look-a-like" image, especially to a car car GM only made 188 of .
Maybe I'm just tired of the Chevelles getting all the notariety! And they have iron heads too.
At 400-600 lbs less we can bench race all nite.
That and my 'ol LT1 reved so well (6800) that I don't think I could stand shifting at 5000, even if it was just as fast.
This should be in the neighborhood of 475-525 with the headers.
My speed shop owner/best friend says he'll have to restrain himself to build it that slow, his slowest BBCs go at least lo-10s.
I don't want to give him too much of a bad rep..LOL
But he is a little light on "street-data" since he builds track motors.
Like a couple of you have mentioned, I think we'll shoot for a true 10 to 1 or so.
I really appreciate the real world experience and advice from several of you with this combo, on the street,
That is invaluable data.
Between the bass like rumble, the N11 mufflers, the solid lifters ticking, and the headers ringing, it'll shout old-school and demand respect.
My biggest concern is heat, but ddawson says I can do it,
Last edited by leigh1322; Jun 23, 2018 at 09:45 PM.
Thanks Bence13-33
I know some aftermarket oval ports would probably run stronger mid-range on the street, but it'll have more than enough anyway.
There is just some car show cred to be had with the winters snowflake, and a factory "look-a-like" image, especially to a car car GM only made 188 of .
Maybe I'm just tired of the Chevelles getting all the notariety! And they have iron heads too.
At 400-600 lbs less we can bench race all nite.
That and my 'ol LT1 reved so well (6800) that I don't think I could stand shifting at 5000, even if it was just as fast.
This should be in the neighborhood of 475-525 with the headers.
My speed shop owner/best friend says he'll have to restrain himself to build it that slow, his slowest BBCs go at least lo-10s.
I don't want to give him too much of a bad rep..LOL
But he is a little light on "street-data" since he builds track motors.
Like a couple of you have mentioned, I think we'll shoot for a true 10 to 1 or so.
I really appreciate the real world experience and advice from several of you with this combo, on the street,
That is invaluable data.
Between the bass like rumble, the N11 mufflers, the solid lifters ticking, and the headers ringing, it'll shout old-school and demand respect.
My biggest concern is heat, but ddawson says I can do it,
Sounds like a solid plan. And yes, there is something cool about using GM parts and making power with them the way the General intended.... Hence why mine still has GM iron oval ports on it...
It'll be cool to see how yours comes out. Are you going to put it on an engine dyno? Do you think you will race the car? A F.A.S.T. class type build would be awesome.
I raced autocross and pro-solo for like 15-20 years. Even a few track days.
Not planning on doing any kind of racing with this one, just cruising. (plan so far .. we'll see)
Yeah I saw those, they look date code correct for an L89 or LS6 and hence the high price tag.
I'm looking at going non-date correct to keep the price down.
My speed shop buddy has a set of 074 aluminums I may wind up with.
They're from an 8 sec race car, late 70s or even 80s date, but huge roller springs ripped off the top of an intake port (it had like 780 lift).
Being welded up now, and re-ported. Should be salvageable, should be OK for non-roller springs, and half the price of ones I have seen on-line.
They'll look fine with the rocker covers on, but you would see the big weld mark with them off. The dates don't match anyway, so who cares?
As long as they are fixed correctly, and don't leak, they are still snowflake heads..
I'll probably never dyno it or race it, but I may use an in car acceleration program to get an idea.
But Atco dragway is only 2 miles away, I may be able to resist for only so long....
Or you could be sneaky and disguise a set of AFR's with an epoxy snowflake! We did some dart aluminum smallblock heads that way and put some double humps on the end. No one notices.....
I like the disguise idea, Sneaky!
But my plan is to start with a stock 70 LS6 setup (450HP).
Then tweak a few things.
(I can't work on the real car now due to some hand surgery, so I'm doing this.)
Headers are worth a lot!, about 70 HP on this combo. So no cast iron manifolds for me.
Pocket porting is worth another 40 HP
All other variables are much less sensitive like 10 or 20 HP.
So I'll keep the stock intake and carb, but drop the compression a little.
Final CompCams dyno prediction looks pretty strong:
What do you think?
leigh1322:
I love the idea, sounds like fun. The numbers that the desktop dyno program is showing seems pretty close, headers are a huge step in the direction of horsepower. Lots of air moving in that motor, you need to be able to get it out as well.
Just a question to anyone who may know. What causes that jagged peak on the torque curve in the diagram around 2500RPM, followed by a small drop off and gradual increase?
454 LS6 Tribute advice requested
