I just recently picked up a full LS swap, I currently have a built 9:1 CP ratio B16 in my car that was boosted, but I took the turbo kit off. I sold a few turbo parts and have some money. What setup would be more fun as a DD?
Full LS motor with CTR’s
Use the LS block with CTR’s and slap my B16 head on the motor
Or put the CTR’s in my B16.
I have used the C-speed racing CP ratio calculator, and I know they aren’t 100% accurate just something to give you a idea. if I do the LS/VTEC with CTR’s it’s saying the CP ratio would be 13:1, def not pump gas friendly! Only reason I would consider the full LS with CTR’s is the compression won’t be crazy high it’s saying 12:1 on a straight LS motor, and I know that would be a little torque monster, with my b16 trans. Opinions??
I would do the LS with the CTR’s. Like you said, the LS/V would be very fun, but 13:1 isnt going to work on the street! The LS with that compression and a few supporting mods, and the B16 tranny should be pretty quick! Also, later down the road if you were to add cams, valvetrain, intake manifold, and a few other things you could increase the power a lot more if you want to. My vote is for the LS with CTR’s! I would rather have low end and mid range on the streets, rather than just top end, and with the B16 tranny it will have a ton of low end!
^yeah that’s what i’m leaning towards! my original LS I had in the car was stock other than a 7lb flywheel and intake but it ran very strong. I just rode in a friends EF hatch with a LS swap a few weeks ago with ITR pistons and it was def fun and very torque!
[QUOTE=JETT_07;1912266]I would do the LS with the CTR’s. Like you said, the LS/V would be very fun, but 13:1 isnt going to work on the street! The LS with that compression and a few supporting mods, and the B16 tranny should be pretty quick! Also, later down the road if you were to add cams, valvetrain, intake manifold, and a few other things you could increase the power a lot more if you want to. My vote is for the LS with CTR’s! I would rather have low end and mid range on the streets, rather than just top end, and with the B16 tranny it will have a ton of low end![/QUOTE]amen to that. right now i’m in the middle of a ls build with ctr pistons. may i recommend that you send the ls head to a machine shop for a little port and polish, not an aggressive one, just to improve flow, something the ls heads lack.
I might be wrong but I thought you could have the relief on the pistons opened up a little more by a machine shop. Like I said though I might be wrong I just thought I had heard that from someone else. Anyone ever done that or heard of it before?
[QUOTE=90IntegraLS1.8L;1912465]i hate to say it but you wont be able to use CTR pistons in an all LS motor. there isnt enough clearances to alow for the valves.[/QUOTE]after i read your post i started checking around and came to the conclusion that i’ll be using itr pistons instead. it will be safer, and the increase in compression would be easier to manage than if having ctrs. thanks for the education.
[QUOTE=arw321;1915928]Incorrect. I have CTR pistons in my LS block with no piston to valve clearance issues. I would recommend claying the motor regardless.
Keep in mind that your static compression ratio will be quite high with CTR pistons in an LS block - i.e. 13:1. The cspeed calculator is not accurate.[/QUOTE]
would it really be 13:1? I doubt that, my friends LS/VTEC with CTR’s was 13:1. I doubt a LS head would bump the compression up that high.
I would trust someones firsthand knowledge over someone saying “his friends anything”. It is his motor I am sure he would have done the math so as not to grenade his motor. I have found its always better to trust firsthand knowlege than secondhand information
no one told me his motor was 13:1, I witnessed it as he put the motor together, got it dynoed and the whole nine yards. Yes it was above 13:1 because it spark knocked on 93 octane, he had to always mix some race gas with it if he wanted it to run strong. He did a compression test and the gauge only read up to 300PSI and it maxed out the gauge. It ran fine on 93 octane once they backed off on the timing, but of course you know he had to sacrifice power to make it run decent on pump gas.
One of the problems with the cspeed calculator is that it does not correctly list the piston to deck height.
You’ll notice that for CTR pistons (PCT) in an LS block the default value is 0.02. This is incorrect as the piston to deck height for CTR pistons in an LS block should be a negative value since the pistons actually protrude past the deck.
Your best bet is to run the calculations yourself. I wouldn’t trust any of the online calculators.
CTR pistons in an LS block with LS head, rods and crank, 3 layer HG and no decking/milling spits out 13.13:1 CR. Sounds pretty close to me.
Note the listed piston to deck height (negative value), vs. what was shown in the cspeed calculator.
Hope this helps.[/QUOTE]
i’m not stuck on using online calculators, it’s just really all I have to go by, unless someone has done a build up or is in the process of doing one for me to gain info from. Is your built LS your DD? How does it run on that CP ratio?
It’s not a DD by any means, and I definitely wouldn’t suggest daily driving a motor similarilly built unless you were very confident in the tuning.
Under load at low RPM there is some minor audible detonation on 94 octane gas.
The car is a blast to drive though. I haven’t taken it to track (or had it on a dyno) so I don’t like speculating what sort of times it would run or how much power it makes.
Basic build is as follows:
LS block 20 over
CTR pistons
LS rods
Micropolished LS crank
ARP rod bolts
Balanced bottom end
J1 b16 tranny
ITR flywheel
Exedy clutch
b18b head ported/polished
Colt race cams
Crower valve springs
RC 310 injectors
b&m fpr
JDM ITR 4-1 header w/2.5" collector
2.5" exhaust