I have heard some unnerving rumors about running the CTR pistons in the b18a/b motor. Something about inconsistant compression and clearance issues.
Has anyone here had any experience with this setup, running CTR pistons in an LS?? I am going to be running them in my LS and I want to know if I am going to have problems with them.
I am not going to be milling my head so the clearances and everything will be normal. The 11.45:1 compression ratio just from the pistons will be enough for me.
I would really appreciate it if someone could help me out with this little dilemma that I am having. I want to know if I should look at a different set of pistons or just go ahead with these.

Later,
BR

 

from what i heard the overbore will have clearance issues in an Ls, Gsr motor. the only head it will clear are b16, ctr, and possibly itr. someone correct me if i'm wrong. but if you want to buy these i have a set for sale brand new

 

So where exactly does it have the clearance problems?? That is one aspect of it that I dont get. Is it something to do with the head and the angle that the valves are in relation to it?? From what I have found out, the angle of the valves is different between a vtec and non-vtec head and that may have something to do with it...

I already have a brand new set of those pistons sitting right here next to me. I am just having second thoughts about puttin them in now due to these complications. I want to be 100% sure on my entire engine buildup, and this is the only part that I am not sure on right now.

Later,
BR

 

there is no reason the overbore would have any more clearance issure than the standard.

Anyways, I just installed my CTR pisonts in the LS/VTEC on Thursday, and it is a little strange to see the dome sticking above the deck, but it looks like it's going to work.

I don't forsee you having any clearance issues with your B18B head. The CTR valve reliefs are bigger than the stock pistons

As far as inconsistant compression. I have never heard of anything about that. Do you mean inconsistant between the cylinders? I would suppose the difference would be in how well the cylinder was bored (how round the machine shop got it).

 

How far along is your project?? Do you plan on having the motor in anytime soon and seeing how it runs?? I would like to know how it works out for you.

On the other hand, the problems that I have heard about with that setup have more to do with the LS head than the block. It was never explained in detail to me so I dont have much more to add on the subject.

I also dont see how an oversized piston would have any effect on how it worked either. It just doesnt make sense.

When I say inconsistent compression I mean that on one stroke it could be a certain psi and then it could vary between each stroke of the piston and give out a different number each time. That is what I was told anyway. I cant grasp the concept enough to explain it anymore because it doenst really make sense to me.
I know a lot about motors and how to build them, but the fact that I dont know everything and then finding this makes me really curious as to what will happen.

Later,
BR

 

the motor is in, it just needs all the connectors hooked up, and vaccuum hoses, etc...plus the oil lines for the LS/VTEC.

The only reason that I can think of that would yeild inconsistant compression, is MAYBE if the rings were installed incorrectly (like the gaps were in a row, or something like that). But I really seriously doubt that would even have an impact. you would just see lower compression on all strokes.

So who has been telling you this stuff? Are they very reputable?

 

Cool, I am curious as to how it is going to run for you. I dont see any reason that it shouldnt...

I was told that from a very reputable source, but he learned of that the same way that I did. Through word of mouth. I am hoping that it works out fine but I am going to keep digging up as much info as I can on this subject until I find out all that I can.
Basically, I just need to find someone who has actually installed and ran CTR pistons in an LS. If I can find someone that has done that then I will have all of my answers.

Later,
BR

 

Anyone have anything else to add to this??
Anyone here ever run these pistons in an LS before??

Later,
BR

 

Yeah, I ran PCT pistons .25mm over (Civic Type R) in a '91 B18A1 with a GS-R head, which yielded a 12.98:1 compression ratio. I had no clearance issues, even with JUN 2 cams. An issue I did have was having to use race gas in it all the time. 101 octane is $3.00/galon.

The over-bore won't have anything to do with clearance issues. A friend of mine has 14:1 Arias 84mm in his B20 VTEC, and the concern with that is having such lift/duration cams (Skunk2 stage 3 cams) that you can't advance the intake and retard the exhaust becuase you'll have concerns with the valves actually hitting eachother during over-lap. Now that's crazy all-motor if I've heard of it.

 

Cool site.....


http://www.bojangs.com/calculator/

 

youll just have to use race gas when you race.....for daily driven you can run pump gass but youll have to retard the timing and hook up a knock sensor./....then when you race just advance and add race gas

 

i was just getting ready to post that site

 

Not such for my motor. It might work alright at sea level, but up here in Denver.... not so much. When I first started that motor, and put load on it, it knocked like a MOTHER F*CKER, even just going through a parking lot in 1st gear. Yes, it was knock, sounds like a can full of bolts being shaken around in the motor.

Least I think it has to do w/ altitude.

 

i think you'll be pretty happy with that setup. here's a dyno plot of my lil bro's car.

98 ls
at the time crower 403's
no camgears
stock rods with arp rod bolts
pct (ctr) pistons
i/h/e
stock fuel system

now we have a set of 404's in it and are about to run a rechipped obd1 ecu to up the rev a bit.

 

Right on, this is the answer that I have been waiting to hear. Someone with experience with this setup...
I do have a few more questions for you though.
What octane gas is he running and what is his timing set at??
What setup was he running for the first run and what did you change to get the final results??

Thats it for now, but I will probably have some more questions for you later about this setup. Thanks again.

Later,
BR

 

well that first run (green line) was actually another ls with i/h/e, 3 angle valve job, bored out tb and cam gears set at +3 intake, -2 exhaust. i guess i forgot to mention that. we just run premium 93 octane gas and the timing is at 16 (stock). when we first finished the motor we even tried running 91 octane gas with timing at 14 and there was no sign of detonation at all. denotation was a concern for us also, so we tried a lot of things to check for it. our next step will of course be the ecu upgrade along with a higher rev limit and a set of camgears. i have to say though this setup is pretty badass. the numbers are ok but it doesnt really do justice for how the motor actually runs. people are usually suprised by how little work we have done to it. especially the ls/vtec guys. as soon as we get everything done, we'll be hitting the dyno once more. ill keep you posted


[Modified by Civic DX 4dr, 7:50 PM 8/21/2002]

 

Where are you getting your machine work done J? In Portland or Seattle? When are you thinking of doing the work? See you soon...

 

Yeah, we should definately keep in touch on our projects. Your the first person that I have met that is taking an LS project as far as I am and we could probably learn a lot from each others work.
I know what you are talking about when you mention how stong the LS runs compared to the dyno charts. It seems that everyone wants a high peak hp and they always shun their midrange power. It is worth losing some top end power to gain even more all the way through the powerband.

You can get a hold of me anytime you want to mynameisbr1@attbi.com so that we can keep up on our projects. I would really like to know how it runs after you chip the ECU. I am about to chip mine too, I just havent gotten my new LS together. I am building it outside of the car so I can take my time doing it and get it all done right.

Later,
BR

 

I am going to have my block worked in Portland at the shop who did my friends B18C1 work when Dan and I rebuilt his motor. They did some awesome work with his motor. They even brought his head back to life after someone installed the wrong valves in it and burnt it to hell.
I dont remember the name of the shop, but you can get it from Dan.

I dont know what I am going to do with the head yet. I would really like to get it done at Portflow, but I dont think I can justify spending over $1000 for the work to do it. I am still looking into other options for the head at the moment.

Later,
BR