Hey guys,
Long story short here. I spun a rod bearing on my original ls heading to work one morning because the pan gasket gave out in 15 degree weather and dumped all my oil. Needless to say I’m finally bringing it back from the dead. It’s quite a complicated build 9at least it starts to confuse me). I have:
Block - B18B1
Crank - GSR
Rods - Eagle H beams (I believe for GSR, since you cant mate ls to gsr?)
Pistons - ITR pistons
Head - ODB1 B16 stock head with stock cams.
I’ve done all the necessary upgrades like water/oil pump, ACL bearings, rings, all the goodies.
My problem that I’m having is that I need to figure out my compression ratio so I know if I can boost down the road or not. I’d like a precise ratio, but I’m having a hard time finding all the numbers to calculate. And trust me, I’ve looked damn near everywhere.
I know ITR’s have higher compression, but gsr’s have lower compression. So I’m thinking around factory compression is where I’d land. The confusing part is when I throw in the vtec head.
Any help?? I’d be very appreciative haha.
so it sounds like a ptr lsv…
did you get the arp rod bolts?
i don’t know for sure the compression ratio… don’t quote me, but i think it’s 10.5:1 and that is fine in order to get boosted. just need a good tuner and right fuel set up
Yeah buddy ARP rod and head studs. What’s PTR? Prelude? Mind you, totally new to honda’s, been doing carburated stuff since I found out what wrenches were lol.
I see most people try to boost at 9.5:1, but somebody told me this thing could be running 11.3:1, which is no good for forced induction. I tried figuring out compression for like I said, when you throw the b16 in the mix and gsr crank, BDC is higher and I BELIEVE cc size of the B16 head is smaller than the 18’s. Not sure.
well, so you’re basically building a gsr engine with itr cams and a b16 head. On the JDM ITR motor, or the b18c5, as opposed to the USDM b18c1 the heads are different. on the b18c5, it uses the b16 head, which you have, and an actual gsr head is called the p72 head i think… not to sure.
basically a ptr is Poor mans type R, and a lot of people using the gsr motors put the b16 head on them and call it good, PTR
Honda’s are the cars to build man, in my opinion. so much style!!!
good luch with your build!
Hey thanks man! I hope it works out, it’s been sitting near it’s grave for about a year. I would have loved to built a GSR bottom end but I found a deal from a guy who had all that bottom end built for pretty cheap, so that’s the route I went.
can’t beat that man! I probably would have done the same thing, I just actually dropped a b18c1` into my DA9! can’t wait for it to be done!
If using USDM ITR pistons, you’re sitting at around 11.3:1 CR. Now, that is your STATIC compression ratio… Depending on what cams you use, your actual compression ratio will be lower (Larger overlap, less actual compression).
In my LSV I’m pushing about the same 11.4:1CR and my tuner said that my Type-R cams will lower the actual compression due to overlap and that it would be fine for moderate boost.
edit
And, honda compression calculators are everywhere… http://zealautowerks.com/bseries.html
This one is quite accurate, but make sure to change the Head Gasket Thickness from the .020" to .030", as that is the only incorrect figure (as far as I understand) on that calculator.
DanG o.O that was some knowledge dropped.
Hell yeah that’s the kind of technical info I’m looking for!
Inputs:
Block - B18
Crank - B18c
Rods - B18c
Pistons - P73-A0
Head - B16
Gasket - OEM - 0.030"
Milling - 0.000
RPM - 8500
Elevation - 1100
Static compression is 11.32! That’s high up there, but like you said I can lower that with cams. The Piston-to-Deck height is only 0.004". Is that the the distance before the head comes higher than the deck?
Will there be any valve/piston clearance issues? That’s the highest compression I’ve ever ran. Sound’s like the timing needs to be dead perfect lol.
Thanks!