SBE LS3 two thoughts
10-02-2021, 03:52 PM
#1
SBE LS3 two thoughts Thinking of getting a long block crate engine from GM to get my rx7 back on the road.
2850 pounds, 6 speed, 3.90 gears, but a street car I drive semi-regularly. Used to have a 402 but I broke it, and I need a semi mild and reliable engine for it.
Engine will get rod mod Ls3 w/ 105mm tb, 1 7/8” long tubes, straight shot CAI, flex fuel capable, carbon RPS clutch -
1) Leave the heads on, ~227/238 on 113+2 cam something “stage 2” ish around 6* of overlap
2) Take the heads off and do a hand cleanup on the ports, cut the heads to ~12:1 compression, flycut the pistons, Johnson 2116 lifters, and run like a 233/246 115+2 cam - still shooting for ~6* overlap, but longer duration and later IVC to shoot for carrying power up to 7000+
I haven’t really seen any cams or putting the IVC at 48-50* for a SBE Ls3, but all the shelf cams are making compromises for PTV clearance. At 12:1 and cutting valve reliefs I think it would work?
Open to input on cams on either plan.
2850 pounds, 6 speed, 3.90 gears, but a street car I drive semi-regularly. Used to have a 402 but I broke it, and I need a semi mild and reliable engine for it.
Engine will get rod mod Ls3 w/ 105mm tb, 1 7/8” long tubes, straight shot CAI, flex fuel capable, carbon RPS clutch -
1) Leave the heads on, ~227/238 on 113+2 cam something “stage 2” ish around 6* of overlap
2) Take the heads off and do a hand cleanup on the ports, cut the heads to ~12:1 compression, flycut the pistons, Johnson 2116 lifters, and run like a 233/246 115+2 cam - still shooting for ~6* overlap, but longer duration and later IVC to shoot for carrying power up to 7000+
I haven’t really seen any cams or putting the IVC at 48-50* for a SBE Ls3, but all the shelf cams are making compromises for PTV clearance. At 12:1 and cutting valve reliefs I think it would work?
Open to input on cams on either plan.
10-02-2021, 04:05 PM
#2
Number 1
Everything doesn't have to be modified
Everything doesn't have to be modified
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G Atsma (10-02-2021)
10-02-2021, 07:06 PM
#5
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With your skills and access to E85 I would hybrid,
Option 2, ~11.5-12.0:1 with Cam Motion LS3 Titan 3 227*/237* 113* + 3.5* .621"/.604"
I would not fly cut for a slightly larger cam though.
Pretty close to your #1 Cam lol.
Just my .02
Option 2, ~11.5-12.0:1 with Cam Motion LS3 Titan 3 227*/237* 113* + 3.5* .621"/.604"
I would not fly cut for a slightly larger cam though.
Pretty close to your #1 Cam lol.
Just my .02
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ddnspider (10-02-2021)
10-02-2021, 09:22 PM
#8
JMO, but here is my slap it together combo. Pull heads, put a Cometic .040 gasket on it w/ the Summit LS3 230/246 cam(forgot the part #, but it's in their thread a lot). Unless you already have the 105TB, you don't need it, but if you have it on the shelf, sure. Same w/ the other parts. A good valve job on the heads is worth it along w/ picking a really good spring for the combo. I would leave the stock lifters and run them. I agree w/ "get it running". That's half the battle these days.
10-03-2021, 10:17 AM
#9
TECH Enthusiast
#1 …. Cars that are running are more fun than cars that are gathering dust.
Is this an FD RX-7?
Is this an FD RX-7?
The following 5 users liked this post by grubinski:
89ThirdGenCamaro3310 (10-03-2021), G Atsma (10-03-2021), lazerlemonta (10-04-2021), rkupon1 (10-09-2021), SLOW SEDAN (10-07-2021)
10-04-2021, 08:34 AM
#10
If I had it on an engine stand, I'd be hard pressed not to give it the full meal deal. Off with the heads, work them a little, mill as much as you dare, fly cut, and use .040 gaskets going back on. That's assuming flex fuel or straight E85. I'd use one of the milder cams mentioned, but have it ground with higher lift...or maybe just use 1.8 ratio roller rockers. Use as much valve lift as you can get away with. Maybe skip the bigger throttle body. Even ported and rod modded, the LS3 intake manifold is probably more of a choke point. Stout engine + light car = lots of grins.
10-04-2021, 10:43 AM
#11
Spanks you've always kept it real with me so I'll do the same...
There's something about Reliability/Simpleness
Also @ 2900 lbs how much power is needed besides 500 @ the crank for Funny? Once you go chasing Hp it Does Not Stop as you Very well Know....
You've got other cars for Speed 😉
There's something about Reliability/Simpleness
Also @ 2900 lbs how much power is needed besides 500 @ the crank for Funny? Once you go chasing Hp it Does Not Stop as you Very well Know....
You've got other cars for Speed 😉
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rkupon1 (10-09-2021)
10-04-2021, 12:01 PM
#12
Yeah the 105tb is completely unnecessary, but it is what I have for the car. To avoid confusion, I own everything already that bolts to the engine - I just need to replace the long block in the car which is currently a hurt 402. I might have to find a cheap 92mm to drive around with lol the 105 was touchy even on a stroker. I put the terminator x on my car without DBW support and it is what I had on the shelf for a cable tb.
Interesting opinions I thought people here would tell me to make it a science experiment lol. Corona you took the wind out of my sails big time as a first reply lmao, and was not expected from the lover of horsepower lol. You guys aren't wrong.
I guess the struggle is if I'll be happy with a basic stock ls3 with a cam, but I keep trying to tell myself that the point is to just get the car driving. If I make it higher compression I at least have flex fuel to play around with and benefit from, and can play with cam timing a bit to try and have a more interesting results. With the higher compression I can push the IVC later and maintain a good DCR, but hopefully extend the RPM range higher using more duration. I like having a higher reving engine in the car. In either case I won't go too crazy with overlap keeping it in the ~6 to 8* range. The biggest risk I guess is having a mismatch of parts if the rod mod ls3 intake just won't let me carry power to 7k+.
Even when my gut agrees with cheap and easy I still have the voice in my head going "it'd be a lot cooler if ya did." It isn't a whole lot of money to do the heads it is just a little blueprinting work.
Yea it is an FD! Makes me sad to see if literally collecting dust, but not the first time. I've had the car since ~2009. The video is with my old 226/242 on 117 stealth cam. I never got a good video of the car after I put the terminator ecu and installed the bigger cam it was wild. It isn't a drag car but I take it out to T&T every once in a while just to play. It is my canyon/street toy I've done 25k miles on the swap over the years.
Yes and no haha, it is basically setup as a road race car for the street. I drive it on a full slick all 4 corners with one groove to make it a DOT tire. My 402 with a small stealthy 0* overlap cam was at 512/509 whp/wtq and the chassis handles it just fine with the right tires on the car. With the bigger cam 242/250 cam and e85 I was just starting to play with I'm confident it was a 140 mph car making 600-620 flywheel and turning 7400 rpm.
With the ls3 I'd really be happier to maintain a powerband that supports 7200-7400 rpm shifts, but drop some overlap and make it nicer to drive around. I'd also like it to not be a complete turd next to my old motor, so I guess a stretch goal would be if I could make 500whp without it being obnoxious with too big of a cam. I think 512whp is really good out of a 226 intake lobe in my old 402. I'd like to see if I could make a respectable number with a smaller than expected cam.
I guess it would make it a little more unique to add some excitement in the results. If I did a cam only ls3 I doubt I'd even put it on a dyno who really needs to see another cam only ls3 dyno with a 226 or 228 intake lobe lol.
Interesting opinions I thought people here would tell me to make it a science experiment lol. Corona you took the wind out of my sails big time as a first reply lmao, and was not expected from the lover of horsepower lol. You guys aren't wrong.
I guess the struggle is if I'll be happy with a basic stock ls3 with a cam, but I keep trying to tell myself that the point is to just get the car driving. If I make it higher compression I at least have flex fuel to play around with and benefit from, and can play with cam timing a bit to try and have a more interesting results. With the higher compression I can push the IVC later and maintain a good DCR, but hopefully extend the RPM range higher using more duration. I like having a higher reving engine in the car. In either case I won't go too crazy with overlap keeping it in the ~6 to 8* range. The biggest risk I guess is having a mismatch of parts if the rod mod ls3 intake just won't let me carry power to 7k+.
Even when my gut agrees with cheap and easy I still have the voice in my head going "it'd be a lot cooler if ya did." It isn't a whole lot of money to do the heads it is just a little blueprinting work.
Spanks you've always kept it real with me so I'll do the same...
There's something about Reliability/Simpleness
Also @ 2900 lbs how much power is needed besides 500 @ the crank for Funny? Once you go chasing Hp it Does Not Stop as you Very well Know....
You've got other cars for Speed 😉
There's something about Reliability/Simpleness
Also @ 2900 lbs how much power is needed besides 500 @ the crank for Funny? Once you go chasing Hp it Does Not Stop as you Very well Know....
You've got other cars for Speed 😉
With the ls3 I'd really be happier to maintain a powerband that supports 7200-7400 rpm shifts, but drop some overlap and make it nicer to drive around. I'd also like it to not be a complete turd next to my old motor, so I guess a stretch goal would be if I could make 500whp without it being obnoxious with too big of a cam. I think 512whp is really good out of a 226 intake lobe in my old 402. I'd like to see if I could make a respectable number with a smaller than expected cam.
I guess it would make it a little more unique to add some excitement in the results. If I did a cam only ls3 I doubt I'd even put it on a dyno who really needs to see another cam only ls3 dyno with a 226 or 228 intake lobe lol.
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DualQuadDave (10-04-2021)
10-04-2021, 01:44 PM
#13
So, an LS3 crate stock at 10.7:1 with a typical cam like a titan 3, 227/237 113+3.5, IVC is around 48.5* and overlap is 6* at .050" - DCR is expected to be around 8.25.
Or the other thought - clip the heads down, cut valve pockets - expected compression around 12:1. Run a ~23x/24x on 115+2.5 cam - IVC is around 75* and overlap is still 6-8* at .050" - DCR expected to be 8.5-8.7. When the heads are off just clean them up and cut them down.
There's always that need/want to learn and try something new I guess. I've seen some stuff this morning that validates some of my thoughts with the longer duration cam I think it'd work just fine just a matter of doing some extra work.
Jegs has a crate motor in stock. Waiting for info from another source, but I think I might get an engine on order today.
Or the other thought - clip the heads down, cut valve pockets - expected compression around 12:1. Run a ~23x/24x on 115+2.5 cam - IVC is around 75* and overlap is still 6-8* at .050" - DCR expected to be 8.5-8.7. When the heads are off just clean them up and cut them down.
There's always that need/want to learn and try something new I guess. I've seen some stuff this morning that validates some of my thoughts with the longer duration cam I think it'd work just fine just a matter of doing some extra work.
Jegs has a crate motor in stock. Waiting for info from another source, but I think I might get an engine on order today.
Last edited by spanks13; 10-04-2021 at 01:52 PM.
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DualQuadDave (10-04-2021)
10-04-2021, 05:40 PM
#15
So, an LS3 crate stock at 10.7:1 with a typical cam like a titan 3, 227/237 113+3.5, IVC is around 48.5* and overlap is 6* at .050" - DCR is expected to be around 8.25.
Or the other thought - clip the heads down, cut valve pockets - expected compression around 12:1. Run a ~23x/24x on 115+2.5 cam - IVC is around 75* and overlap is still 6-8* at .050" - DCR expected to be 8.5-8.7. When the heads are off just clean them up and cut them down.
There's always that need/want to learn and try something new I guess. I've seen some stuff this morning that validates some of my thoughts with the longer duration cam I think it'd work just fine just a matter of doing some extra work.
Jegs has a crate motor in stock. Waiting for info from another source, but I think I might get an engine on order today.
Or the other thought - clip the heads down, cut valve pockets - expected compression around 12:1. Run a ~23x/24x on 115+2.5 cam - IVC is around 75* and overlap is still 6-8* at .050" - DCR expected to be 8.5-8.7. When the heads are off just clean them up and cut them down.
There's always that need/want to learn and try something new I guess. I've seen some stuff this morning that validates some of my thoughts with the longer duration cam I think it'd work just fine just a matter of doing some extra work.
Jegs has a crate motor in stock. Waiting for info from another source, but I think I might get an engine on order today.
You know this one ..good Reference
https://www.motortrend.com/how-to/09...er-heads-swap/
10-04-2021, 05:52 PM
#16
Your also still getting Oscar nominations..3 Guys @ work gave me there vote.
10-04-2021, 07:18 PM
#17
TECH Enthusiast
10-04-2021, 09:41 PM
#18
Yeah the 105tb is completely unnecessary, but it is what I have for the car. To avoid confusion, I own everything already that bolts to the engine - I just need to replace the long block in the car which is currently a hurt 402. I might have to find a cheap 92mm to drive around with lol the 105 was touchy even on a stroker. I put the terminator x on my car without DBW support and it is what I had on the shelf for a cable tb.
Interesting opinions I thought people here would tell me to make it a science experiment lol. Corona you took the wind out of my sails big time as a first reply lmao, and was not expected from the lover of horsepower lol. You guys aren't wrong.
I guess the struggle is if I'll be happy with a basic stock ls3 with a cam, but I keep trying to tell myself that the point is to just get the car driving. If I make it higher compression I at least have flex fuel to play around with and benefit from, and can play with cam timing a bit to try and have a more interesting results. With the higher compression I can push the IVC later and maintain a good DCR, but hopefully extend the RPM range higher using more duration. I like having a higher reving engine in the car. In either case I won't go too crazy with overlap keeping it in the ~6 to 8* range. The biggest risk I guess is having a mismatch of parts if the rod mod ls3 intake just won't let me carry power to 7k+.
Even when my gut agrees with cheap and easy I still have the voice in my head going "it'd be a lot cooler if ya did." It isn't a whole lot of money to do the heads it is just a little blueprinting work.
Yea it is an FD! Makes me sad to see if literally collecting dust, but not the first time. I've had the car since ~2009. The video is with my old 226/242 on 117 stealth cam. I never got a good video of the car after I put the terminator ecu and installed the bigger cam it was wild. It isn't a drag car but I take it out to T&T every once in a while just to play. It is my canyon/street toy I've done 25k miles on the swap over the years.
https://www.youtube.com/watch?v=Yocq...hannel=dankmac
Yes and no haha, it is basically setup as a road race car for the street. I drive it on a full slick all 4 corners with one groove to make it a DOT tire. My 402 with a small stealthy 0* overlap cam was at 512/509 whp/wtq and the chassis handles it just fine with the right tires on the car. With the bigger cam 242/250 cam and e85 I was just starting to play with I'm confident it was a 140 mph car making 600-620 flywheel and turning 7400 rpm.
With the ls3 I'd really be happier to maintain a powerband that supports 7200-7400 rpm shifts, but drop some overlap and make it nicer to drive around. I'd also like it to not be a complete turd next to my old motor, so I guess a stretch goal would be if I could make 500whp without it being obnoxious with too big of a cam. I think 512whp is really good out of a 226 intake lobe in my old 402. I'd like to see if I could make a respectable number with a smaller than expected cam.
I guess it would make it a little more unique to add some excitement in the results. If I did a cam only ls3 I doubt I'd even put it on a dyno who really needs to see another cam only ls3 dyno with a 226 or 228 intake lobe lol.
Interesting opinions I thought people here would tell me to make it a science experiment lol. Corona you took the wind out of my sails big time as a first reply lmao, and was not expected from the lover of horsepower lol. You guys aren't wrong.
I guess the struggle is if I'll be happy with a basic stock ls3 with a cam, but I keep trying to tell myself that the point is to just get the car driving. If I make it higher compression I at least have flex fuel to play around with and benefit from, and can play with cam timing a bit to try and have a more interesting results. With the higher compression I can push the IVC later and maintain a good DCR, but hopefully extend the RPM range higher using more duration. I like having a higher reving engine in the car. In either case I won't go too crazy with overlap keeping it in the ~6 to 8* range. The biggest risk I guess is having a mismatch of parts if the rod mod ls3 intake just won't let me carry power to 7k+.
Even when my gut agrees with cheap and easy I still have the voice in my head going "it'd be a lot cooler if ya did." It isn't a whole lot of money to do the heads it is just a little blueprinting work.
Yea it is an FD! Makes me sad to see if literally collecting dust, but not the first time. I've had the car since ~2009. The video is with my old 226/242 on 117 stealth cam. I never got a good video of the car after I put the terminator ecu and installed the bigger cam it was wild. It isn't a drag car but I take it out to T&T every once in a while just to play. It is my canyon/street toy I've done 25k miles on the swap over the years.
https://www.youtube.com/watch?v=Yocq...hannel=dankmac
Yes and no haha, it is basically setup as a road race car for the street. I drive it on a full slick all 4 corners with one groove to make it a DOT tire. My 402 with a small stealthy 0* overlap cam was at 512/509 whp/wtq and the chassis handles it just fine with the right tires on the car. With the bigger cam 242/250 cam and e85 I was just starting to play with I'm confident it was a 140 mph car making 600-620 flywheel and turning 7400 rpm.
With the ls3 I'd really be happier to maintain a powerband that supports 7200-7400 rpm shifts, but drop some overlap and make it nicer to drive around. I'd also like it to not be a complete turd next to my old motor, so I guess a stretch goal would be if I could make 500whp without it being obnoxious with too big of a cam. I think 512whp is really good out of a 226 intake lobe in my old 402. I'd like to see if I could make a respectable number with a smaller than expected cam.
I guess it would make it a little more unique to add some excitement in the results. If I did a cam only ls3 I doubt I'd even put it on a dyno who really needs to see another cam only ls3 dyno with a 226 or 228 intake lobe lol.
Well, I really like the car and like what you are doing with it. Let me change my "slap it together" combo some. Given the use and the parameters. I'd slap a Fast intake on it for sure, and put an LLSR in it. To stay hyd for this, I think, is a waste. The maintenance on a LLSR really is not bad at all. Even easier on valvetrain, to a certain degree. You can meet your dirveability and rpm requirements way easier w/ less trade-offs. Give it some thought.
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Corona (10-05-2021), NAVYBLUE210 (10-04-2021)
10-04-2021, 09:49 PM
#19
TECH Senior Member
