Just put a b16a1 in my 90 CRX....well I may have a cracked bottom end. But...say its cracked...can I replace it with a B18 block..or B17? and if so what year? 90-91 I would guess. I have seen the conversion done somewhere..but I can't find the site now.

 

are you asking about a LS/VTEC? if so, build it right the first time. Its not as simple as just putting the head on the block, there are some modifications that need to be done and building the bottom end up is recommended, the LS block was not meant to rev to 8000+ RPM.

 

what exactly is cracked? the block? if interested, im doing an ls/vtec and have a b16a block, crank and rods for sale very, very cheap

 

here you go i just wrote this article its not totally done yet so bear with it.


Ls/vtec.
By.Chris Vallee

Ls/vtec is the mating of the b18a/b to a b-series Vtec head like the b18c1/5 b17a or b16a head. The amazing part about this swap is that these blocks did not come with
Vtec so there are a few mods you need to know to do the swap right.
A. GENERAL INFORMATION
1.The Down Side. The b18a/b has a low r/s ratio 1.53 wich is not bad compared to the 1.58 of a gsr. The b18a/b was not made to rev over 7000 r.p.m's it has poor lubricartion,bad rod bolts, rods,oil and water pump, and piston valve relifes. You can fix all these's problems, you can install vtec block oil squiters for lubricating the rods and piston. This helps saves pistons,rods and bearings at high rpm's. You can install Arp rod bolts. And get upgraded rods or shotpeined. Also some vtec pistons would not hurt too.
2. Oil line. The ls block does not have a vtec oil passage(you need this hole to produce the oil pressure to lock the vtec lobes rocker arm)you will need to tap the hole on the head or weld it shut. When threading it shut use a 1/8ntp fitting you will need to have a machine shop thread it for the 1/8th fitting and then just screw it in. Next you have to make a external line from the oil pressure sender to the head. Use a 4an to 3/8th ntp plug on the head to a stealbraided line to tee'd of to the oil pressure sender hole. You will need a 1/8th tee fitting,a 1/8th to 3/4th's fiting for the line to the tee, a 1/8th to 1/8th adapter to plug the block, and plug the oil pressure sender in the back of the tee. So it will look like this (the T will be used as the tee fitting)
18th to1/8th adapter T oil presure sender sensor
oil line to head
A suggestion is to somehow have the tee fiting so it is not directly on the block (especially if you are installing a oil pressure gadge) it can literaly crack the threads and you wil shoot oil everywhere. So try to run ss lines to someplace that can support the weight.
3.gaskets and misc. head gasket wise, you will use the ls headgasket.
4.Dowle pins You will have to modify the head for the dowle pins to fit. You have to move and redrill the dowle pins to be able to fit the head. On the intake side right below where you put thw 1/8pipe fitting that plugs the vtec oil passage you will drill and install one of the dowle pins and on the other side at the exact same point.
5.Timing belt. You will use the ls timing belt if you use the ls water pump and the gsr if you use a vtec B17/16 or B18c1/5.
MISC
6.Head studs. You will use the vtec head studs for the ls/vtec set-up. I suggest arp if you want to spend the money.
7.Oil Pump. The oil pumps on the ls's suck so you might want to upgrade to a vtec one or a b20 they are same part number as the gsr.
8.Heads. There are many heads you can use and there are little differnces in all of them.
First off there is the gsr head wich give you a higher compression than the other b-series heads because of its 41.6cc combustion chamber. The smaller combustion chamber makes .2 more compession. Then there is the b16/17a head wich are the same the only difference is that the b17a has a p61 stamped on the back of the intake manifold the b16/17a head is a better flowing head 5.25% infact and a larger combustion chamber 42.7cc's. Then there is the type r wich flows even better than the b16a head and has the same combustion chamber. To put this in perspective the b18a/b has a 45cc combustion chamber.
9.Gsr Block Girdle. You can use the gsr block girdle on the ls, this will reinforce the bottom end and keep the moving parts in its place. All you need to get is the 3 main caps in the middle, bolts,windage, oil pan and oil pick up.
10.Pistons. You can use any b-series vtec piston in your ls block. Any 1.6 b-series piston will be raised by about onw full point in the ls block like the b16a(pr3 pistons will raise it from the stock 10.2 comp in the b16a to 11.4ish in the ls block so keep this in mind when building the ls block. Also keep in mind about the combustion chamber size(See heads). 1.8 pistons will usually most of the 1.8 pistons you can take .2 off of the stock comp with a b16a head and that should be around it. With gsr add .2 comp to the stock comp.( Warning: these is all estimate they could be off a little).

 

hahahahaha...listen to rainforest, he know waht he's talking about. That was funny Chris--a warning.