Too much Compression?

[MAGONSTERZ68]

Is this too much compression to add an LSA from a CTSV?
Engine is LS3, stock heads are 5 angle valve cut and ported.
OK with HP but looking to make more toque at lower rpm.
Current dyno is 467 hp, 410 tq to the wheels, 3200 yank stall, stock crank, stock rods, forged pistons.
BTR STG2 cam:Specs: 225/238 .612"/.585" 113+3
3800lb, 68 Camaro conv. w/ full tank and driver, 3:42 rear gear, 4l60E, 1 7/8 headers to full 3" xpipe exhaust.

bore 4.065
stroke 3.622
gasket .051
deck -.009
piston cc 4 cc
chamber 64.5

static comp 10.94

[TheJDMan]

3.42:1 rear gear, that's your problem! With the 4L60E you need to be around 3.90-4.10:1

[MAGONSTERZ68]

Dang it,
its my daily driver and like the low freeway rpm, would swapping in Sonnax 2.84 input carrier turning “wide ratio” 3.06 first to 1.63 second to a “close ratio” 2.84/1.55 first/second gearset help?

Sounds like its one or the other, gear for torque or gear for low rpm fwy speeds.

Rear end is 8.5 GM 10 bolt so can use 3.73, 3.90 or 4.10 to fit my carrier.
So if i want to move the torque range down to a more usable stoplight to stoplight application it'll be a gear change OR yank the block and stroke it, 415 here i come!(wishful thinking)

Currently 26" tall tires puts me at 2100 rpm at 70 mph
If i swap out gears im looking at the following:
3.73's 2300 rpm at 70 mph
3.90's 2400 rpm at 70 mph
4.10's 2530 rpm at 70 mph

[68Formula]

You want to take a built LS3 and add an LSA blower? You must really hate your trans. :)

Probably a stretch on pump gas, unless you have E85 available or add a Methanol Injection kit. And CA is only 91 Octane for premium, right? The cam may help a little since it reduces dynamic compression, but it'll still be pretty high for boosted. You'd need to make sure you have a large and efficient external intercooler, and conservative tune for sure. But then you'll need a better transmission too, like a 4L80E or T56 Magnum. Sounds pretty expensive when you add all that up.

I'd probably just compromise by putting the 3.73s in it and call it good.

[MAGONSTERZ68]

On that note plan to swap in 3.73's soon as already scheduled down time for LS1 rear disc brake swap.
Seems to be the logical and cost effective compromise given it's a daily driver and not dedicated track car.
NITROUS?
What are your thoughts on 50 hp wet shot of nitrous? or can stock fuel system handle a 50 dry shot? Has 255 lph walboro in tank pump and stock LS3 injectors.
Would this require a timing controller to pull timing on wet or dry 50 shot?

[mean buzzen half dozen]

Your squish band is pretty big. If you get it tighter, less likely to detonate, but that will bump up your compression.
Open up the chamber get closer to a zero deck height & a thinner head gasket. That will help out tremendously.

You need to lower your compression a bit for the blower anyways.
I am pretty sure you can add a dry shot of Nitrous if you program your ECU. Ask NOS if you can.

Also, your cam is probably not to friendly on mileage with 3.42's at 70 MPH 2100 RPM, probably more fuel efficient at 2300 RPM.

[MAGONSTERZ68]

Your squish band is pretty big.
If you get it tighter, less likely to detonate,?
but that will bump up your compression. ? almost 11:1 already
Open up the chamber, agreed at least 70 cc? would help to fly cut piston relief grooves? only at 4 cc now.
get closer to a zero deck height? already sits above deck .009
& a thinner head gasket. ? smaller than oem .051
That will help out tremendously.? how

You need to lower your compression a bit for the blower anyways.
I am pretty sure you can add a dry shot of Nitrous if you program your ECU. Ask NOS if you can.

Also, your cam is probably not to friendly on mileage with 3.42's at 70 MPH 2100 RPM, probably more fuel efficient at 2300 RPM.


If you get it tighter, less likely to detonate,but that will bump up your compression.
Im almost 11:1 already
Open up the chamber
Agreed at least 70 cc? can i to fly cut piston relief groove to lower compression? at 4 cc now.
get closer to a zero deck height ? already protrudes above deck by .009
& a thinner head gasket. ? smaller than oem .051
That will help out tremendously.? how
So im less efficient due to cam timing at 2100 vs 2300? will consume more fuel than at a higher RPM?

[mean buzzen half dozen]

If you get it tighter, less likely to detonate,but that will bump up your compression.
Im almost 11:1 already
Open up the chamber
Agreed at least 70 cc? can i to fly cut piston relief groove to lower compression? at 4 cc now.
get closer to a zero deck height ? already protrudes above deck by .009
& a thinner head gasket. ? smaller than oem .051
That will help out tremendously.? how
So im less efficient due to cam timing at 2100 vs 2300? will consume more fuel than at a higher RPM?

IIRC, you want a squish band closer to .038" - .040".
I miss understood on your deck height. .009" above is fine.
So your quench is good.
PM sent

[68Formula]

How about a wide ratio T56 Magnum with 4.56 gears? The first gear would be like running your current trans with 4.43 rear gears, and the overdrive would still put you below 2100rpm @ 70mph. Fuel economy would increase. Plus it'd be a lot stronger than the 4L60E if you add power later on.

[MAGONSTERZ68]

ah i see, got it thx

[MAGONSTERZ68]

How about a wide ratio T56 Magnum with 4.56 gears? The first gear would be like running your current trans with 4.43 rear gears, and the overdrive would still put you below 2100rpm @ 70mph. Fuel economy would increase. Plus it'd be a lot stronger than the 4L60E if you add power later on.


Read my mind, just making due for now with what i have due to funds.
Already procured a TR6060 and working on piecing together a 9" with 411's, wouldnt 456s be too steep for 1st gear, sounds like could leave in second...

[68Formula]

Read my mind, just making due for now with what i have due to funds.
Already procured a TR6060 and working on piecing together a 9" with 411's, wouldnt 456s be too steep for 1st gear, sounds like could leave in second...

I was basing it on the late model Camaros that use the 6L80E (4.03 1st gear) with 3.42. Pretty much as deep as you want to go and still have a usable 1st gear, BUT the tires are taller than yours. So taking that into account, 4.30s would be closer to equivalent, but I like the idea of 4.11s to give you a little longer legs on the highway.

What vehicle is the TR6060 out of? There's a few different ratio sets if it's an OEM style. Did you confirm the gear ratios?

[MAGONSTERZ68]

I was basing it on the late model Camaros that use the 6L80E (4.03 1st gear) with 3.42. Pretty much as deep as you want to go and still have a usable 1st gear, BUT the tires are taller than yours. So taking that into account, 4.30s would be closer to equivalent, but I like the idea of 4.11s to give you a little longer legs on the highway.

What vehicle is the TR6060 out of? There's a few different ratio sets if it's an OEM style. Did you confirm the gear ratios?


trans is out of 2012 Camaro

- - - Updated - - -


You want to take a built LS3 and add an LSA blower? You must really hate your trans. :)

Probably a stretch on pump gas, unless you have E85 available or add a Methanol Injection kit. And CA is only 91 Octane for premium, right? The cam may help a little since it reduces dynamic compression, but it'll still be pretty high for boosted. You'd need to make sure you have a large and efficient external intercooler, and conservative tune for sure. But then you'll need a better transmission too, like a 4L80E or T56 Magnum. Sounds pretty expensive when you add all that up.

I'd probably just compromise by putting the 3.73s in it and call it good.


3.73 gear install scheduled for tomorrow.

[rpol78]

I'd go poke around on Camaro5. Several over there are bolting LSA superchargers on LS3s (stock and cammed). It sounds like you're running pretty much a stock rotating assembly with a BTR cam. The challenge will be how much boost can you run before you need meth injection, higher octane fuel, or E85. If you go that route you may want to swap the LS3 head gaskets for the LS9 gaskets.

[MAGONSTERZ68]

I'd go poke around on Camaro5. Several over there are bolting LSA superchargers on LS3s (stock and cammed). It sounds like you're running pretty much a stock rotating assembly with a BTR cam. The challenge will be how much boost can you run before you need meth injection, higher octane fuel, or E85. If you go that route you may want to swap the LS3 head gaskets for the LS9 gaskets.


Correct on all notes lol!
Since post i have built a 10:1, K1 cranked, H beam rodded, Darton sleeved 6.0 alum block, J&E piston 4.125 for a 388 cu in small block with CNC LS3 heads, LSA gasket .054, stuffed with ARP everything and a topped off with Johnsons slow bleed lifters, BTR PDS stage 2 cam and a whipple 2.9.
Talk about snowball effect! waiting on 10 rib ATI set up to show and 1200 cc injectors before final mockup and install.

[rpol78]

I should have looked at the posting dates.

I know about the snowball effect, in process on a LS396 - LS9 block, JE/Callies rotating assembly, LS9 CNC heads, custom cam, and a Kong 2650. Took forever to get the rotating assy worked out.

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