OK a bit of Back ground on the B20vtec first.
Way back in the day (1997) when the B20b Honda CRV was launched, a Small company realised that the B20b had been made using the B16/18 block using different sized sleeves/pistons (84mm) there fore they figured that a Vtec head would fit, SSworks were one of the first company's to utilise the B20 for there race car and managed to set a record lap of Tsukuba in a FWD allthough this has now been beaten with the same car running a super high comp B18.
In 1999 the higher compression B20z1 was released this engine produces a further 19bhp and reved to an extra 1300rpm in standard trim.
Here are the 1997 onwards B20 specs.
B20B1 128bhp@5500rpm 1972cc 9:1 Compresion ratio.
B20B3 128bhp@5500rpm 1973cc 9:1 Compresion ratio.
B20Z1 147bhp@6800rpm 1973cc 9.2:1 Compresion ratio
B20Z3 128bhp@5500rpm 1973cc 9:1 Compresion ratio.
The above are what i have found and may be wrong.
Since 1997 the B20 has become a very common engine build in the states and is becoming a common engine buildin the UK.
Ok here is breif run down of my original B20 build before i started adding lots of go faster goodies,
B20z1 complete Bottom end.
B16a2 complete Head. inc inlet maniold, Injectors, Distributor cams etc.
Golden eagle VTec conversion Kit.*
B16 Exhaust manifold.
B16 Flywheel and clutch.
B16 Oil pump,
B16 UK CRX VT Y2 Gear box.
B16 Starter motor
B16 Bottom Pully.
B&M Fuel pressure Regulator + Gauge. (set to 60psi)
APR head studs
Golden Eagle Block Gaurd.
That is every thing i needed to build my B20vtec.
* You can buy the parts seperatly and DIY or buy the GE kit which has every thing you need.
I used the Golden eagle Vtec conversion kit which can be seen here,
Which comes supplied with following:-
Oil filter sandwich plate.
Vtec oil supply line.
Fitting for the Head.
Tube of Honda Bond,
Oil way Plug.
Tap for the above.
Re-worked head gasket (84mm+ for B20, 81mm + for ls/vtec)
Now this kit means there is absolutely no Machining required, other than tapping the head for the Oil way plug.
You can of course buy all the parts completly seperate and DIY, both ways work fine and neither are right or wrong,
I personaly went for the GE kit for ease of use nothing more nothing less,
Now the main questions I have been asked lately are :-
Q. Which block is better B20b or Z.
A. It depends on your application, The Z has a higher compresion and produces close to 20bhp more in stock form there fore for a basic build the Z would produce more power, But if you plan on fitting pistons and rods the B20b would be better as its usually cheaper to buy due to less power.
Q. Can i turbo the B20,
A. Yes you can B U T it was not advisable on stock sleeves due to them being alot thinner than standard B16/18 sleeves and they do not cope to well with detination.
I looked in to turboing mine but all the info i came up with said NO unless i planed on fitting a set of Darton/Benson sleeves.
Even at low boost a small amount of DET would mean potentional engine Failure. How ever, there are a few guys running B20Vtec Turbo's now and using forged internals and good tuning they have been making some good power, 2 of these guys are on this forum.
Q What cams can i fit.
A On a stock built B20Zvtec, i have run ITR cams, and stock B16a2 cams, Sowler has run stock a2 cams with a 1mm head skim with no P2V issues, i have run a B20b with Buddy club Spec 3+ cams on stock internals with a 15 thou head skim and no issues.
Q. Which Head do i use.
A. You can use any of the Bseries Vtec heads they will all work, On a rough principle it depends on application, B16a heads tend to flow better than say a B18c4 head, but the B18c4 head has bigger Inlet ports, smaller combustion chamber and coupled with a good inlet manifold would be good for more torque, the ITR head is probably the best "off the shelf" head but the B16 is by far the cheapest and easiest to find.
Q. How much will it cost me to build a B20
A. This is quite hard really as it depends on how much you get certain components for, For example I paid £500 for the B20z bottom end, I borrowed the B16 head from Nick in replacement for my old 1 when it was removed, the conversion kit I ordered via my self at Rare Import Parts so cost me trade, along with the new oil, spark plugs and timing belt inc the rest of the sundrais it came close to £1000.
In a nut shell expect to pay between £800-£1200 on a B20vtec build.
Q. What exhaust Manifold do i need.
A. All B series exhaust manifolds will fit I have used stock B18, B16 and after an market 4-1 before i went to my custom header, all fitted fine under the stock B20 sump. If you do decide to fit a Crank girdle you will have to fir a B18 exhaust manifold due to the Sump sitting lower.
Q. What can i rev up to safely???
A. Again a hard 1 really, I rev mine to 8500rpm all day every day and have done for over a month and 1000+miles with no adverse affects, Allthough if you want to be super safe Simply dont rev higher than stock B20 rev limit. What you will find is that the B20vtec once in vtec will rev very easily and quickly to about 7500rpm, in basic form it starts to die out on power around 7300 and reving up to 8k is not needed really as it has noticably stopped making power. (edit, i have been running a b20b build with BC3+ cams to 8500 for about 8 months lots of drag racing and no issues)
Q. What is the B20 like on fuel,
A.This is 1 of the best things about B20's I actually have better fuel consumption than with the B16, due to the fact that you drive in a gear higher, I regularly pull away in 2nd gear with no problems, also i dont have to rev the nuts off the B20 i just simply put my foot down and she pulls , where as in a b16 you drop it down a gear and tec it away. Lots of people who have the B20 have said the same, MPG is better with the B20.
Q. What timing belt do i use.
A.Either a B18 or B20 cam belt (make sure it matches the Water pump ie B18 pump=B18 belt, YOU CANNOT USE A B16 BELT/WATER PUMP.
Q. What Gear Box do i use,
A. Ideally the Gear box that you have with your car (unless your doing the B20 conversion to a D series) I used the UK VT Y2 gear box.
Q. What Flywheel/Clutch do i use,
A. Again i used the B16 flywheel and clutch, the B16 clutch seems to take the B20 fine. I have done 1 track day and a lot of HARD launches with the Stock B16 clutch and it has no signs of slipping yet, All though once I start upping power Iwill be getting a better clutch due to the increase in torque.
Q. What mangment do i need,
A. I am using aPW0 OBD0 ecu with a remap, Allthough I ran it for a few weeks on stock ecu but with 60psi fuel pressure for safety, I DO NOT recomend running you B20 on a stock ecu, a remap or upgrade ECU would be the safest possible thing, There are plenty of people on this forum who could remap your car and i am sure a good base mapped chip will be available soon.
Q. What injectors do i need.
A. I am running the stock B16 injectors at 60psi. Different injectors will require remapping, H22 345cc injectors are a popular plug and play chocie though.
Q. Where do i need to have Vtec cut in.
A. I have mine set at 4600 which is about right, as with Vtec in the stock settings its a little to high and comes in with a brutal kick. how ever it depends on the spec of your motor.
Q. What does it Drive like, is it ok in traffic.
A. Its perfect in traffic it doesnt kangaroo about or have problems with over heating, i have noticed under bonnet temps being a bit higher but the Temp gauge is always about 1/3rd of the way up and never goes any higher.
Q. Is the stock CRX water system enough for the B20
A. Yes. i have had no problems with over heating even with mine in a tuned state at high RPM at the track days.
Q. Can i build a B20vtec my self,
A. If you can perform a Head gasket replacement on your car and you can swap an engine over then YES you can its as easy as that.
Q. What power will it make.
A. I have yet to Dyno mine so i have no stats to show, All though i know of 3 different B20vtec's that have made pretty good power.
Example 1 B20b home made in every way shape and form stock B16 head, intake, exhaust, walker OE exhaust system, slightly mapped ecu to cover fueling, the car made close to 180bhp and 150ft/lbs.
Example 2 B20b Home made with stock B16 ecu, manifold with a custom exhaust system, Cold air intake car made 185bhp, 156ft/lbs.
Example 3 B20z GE conversion kit, AEBS inlet manifold, Comptech exhaust, B18 ITR ecu, Tanabe exhaust 8k rev limit, ITR injectors, 196bhp, 159ft/lbs. Now these arent exactly good to go on as all are different dyno's on different days, BUT expect a good increase in torque over a stock B16. And at the end of the day its the Torque that makes the difference NOT the BHP.
Roughly a Basic Built B20b will see around 175/180bhp, and a B20z around 190Bhp with around 145/150ft/lbs.
OK hopefully that has answered alot of the Questions you have been having.
You may want to get your self a Haynes Manual or Honda engine manual for this job.
I am not going to run through everyting piece by peiece as if your confident enough to under take the task of building the B20 vtec you should be compitent enough to understand how to fit/re-fit the parts mentioned.
Take your desired B20 Bottom end and check it over for any problems, cracks etc, clean the face and check the bores for marks or rust etc.
If you are going down the DIY route make sure you have all the right parts, or BUY THE GE conversion kit as it saves with this problem as it does with alot of other you will find along the way.
Its about now that you want to fit your NEW honda water pump, its always advised to fit a new water pump for the sake of a few quid it could save you from engine failure down the line, once thats done you should fit your new Oil pump, you can use the oil pump from a B16 or B18vtec, its advised to use a Vtec oil pump as there designed to pump oil at higher RPM's than the stock B20 item, when fitting the oil pump use Honda bond to seal it and stop it leaking, Also if your fitting a Crank girdle now would be the right time top do so, if you are going to fit a crank girdle you will also need the following items,
B18 windage tray
B18 Oil pick up. along with your Girdle,
B18 specific exhaust manifold
Refit your appropriate sump and items to the bottom of the block. Make sure the sump is tight.
Now you can fit your Oil filter sandwich plate and filter
Now at this stage you may want to fit your Block gaurd, I am not a fan of head studs, and personally prefer Block posts,
see here for info on block posting:
some good info
Install your head studs if your using them the head studs have instructions in with them on how to fit as does the Block guard i used a Golden eagle guard and it was an absolute pain in the AR5E to fit i had to machine it down by about 2mm inside and out to be able to get it in and ot took alot of honing to re-align the bores, Now when fitting the BG its a good idea to have the bore's checked after its fitted as in some extreme cases the gaurd can cause the bores to mis shape badly, which would cause tight spots and can caus hot spots on the piston which could lead to seizure
Now you need to add fittings to the back of the block for your PCV system,
To under stand the PCV system read these threads and it will help you to understand why you need a PCV system on your B20 build
Now these are the Part numbers for the Honda fittings and washers
12207-634-300 for the washer you will need 1 of these
11107-PK2-003 For the Nipple fitting.
You can see the fittings i made for my Block from using the original fitings and drilling them and adding my own fittings, this idea was given to me by Mark E.
It has come to light in testing that 2 fittings on the back of the block can be to much, as the fitting on the left is the return gallery from the head,
adding 1 or 2 more breathers to the front of the rocker cover is also a good idea.
Once your new fitting is in your Block your ready to start building up your head.
As with the Block make sure the face is clean and the head is ok you may want to have it Pressure and crack tested and a small skim before using it. Now i fitted new B18 LMA's to my build as whilst the head was off the car it was easy to do, i also replaced the Valve stem oil seals, cleaned the Combustion chambers and re-seated the valves. its not necessary to do this but i am a bit anal when it comes to building engine's i dont like taking risks.
Now with the head up turned you need to Plug this hole
This is the oil supply hole from the B16 block which is not present on the B20 block and if not plugged will cause oil to seep out all over the back of your engine,
Next you need to add the fitting to the head for your oil supply there is a fitting you need to remove from the B16 head and replace with the new fitting for your supply line.
OK now you need to add your dowels now depending whether you bought the GE conversion kit or not this is where it gets a bit tricky, the GE conversion kit provides you with stepped dowels which slot in the B20 block and allow the B16 head to fit no problems, If how ever you went down the DIY route you will need to drill either the block or head to except the sized dowells you are using, yet another reason to use the GE kit.
Once the dowels are sorted you now need to put your head gasket on to the block, again the GE conversion kit provides you with a re-worked HG which will fit in place perfectly, if your going DIY you will need to adapt your HG to suit the sized holes for your dowells, so once the HG is in place the head is now ready to be put on your block this is easier with the head studs as it will just slide down in to the correct postion, once the head is on check to make sure you have not trapped the HG and that all is sitting correctly, Now using the CORRECT tightening guide lines for your choice of Head studs/bolts tighten away, once tight it add your Vtec oil supply line and it should resemble this
Now refit your Inlet manifold and the appropriate sensors back to your head and block, the B20 water coolant temp sensor is not in the block like a B16 its situated on the thermostat hosing a lengthened the wires and added the correct plug for the sensor, you can start timing you're engine up ready for your cams to be re-installed, once the cams are in and the timing has been set fit your new Cambelt,
slowly turn the engine over by hand and feel for any problems, you may want to lock the Vtec in position to feel for Piston/valve touch, you should not have any touch with the GE conversion kit if you have a stock head.
if all is well your ready to start fitting all the ancillaries like the fly wheel, clutch, gearbox, alternator and starter motor back to the engine.
You can now fit the distributor HT leads and new spark plugs as well.
Now you're ready to drop your engine back in to your Car, once in and bolted up fit your Drive shafts, and wire the engine up,
Fill the engine and gear box with the correct oil, MTF 90 for the Gear Box and 10w40 for the Engine, make sure you have the correct dipstick for the sump you are using. Add your coolant to the system and bleed as best you can your engine should now be ready to be started, BUT before you do make sure you have tightened every thing up and that you have no leaks etc.
You can now start her up, Once started check your Fuel pressure (if using a FPR to control fueling) leave it to warm up check for CEL's and leaks, once up to operating temps, switch off, recheck all your work and then go for a spin, take it steady and keep your eye on the gauges, it may be best to have some one follow you to let you know if any thing is dripping from the car whilst driving, once your happy the engine is fine build the revs and try VTec if all is well slowly build up the revs more and more listening out for any bad noise like DET etc,
Hopefully your car is running sweet and your happy with your new toy,now go out and Play.
My self will not be held responsible for you fukcing up your engine, or hurting your self or some one else from this write up. If your not compitent or confident enough to undertake the JOB do not do it.
Please ask questions if you're unsure via this thread.
I hope this has been help full enough .
OK I will update this particular section as and when i relpace certain parts.
First tings first once you have you B20Vtec running it would be a good idea to get it on the correct managment wether it be a stand alone like Hondata or just a re-mapped stock ECU, Hopefully as I go along this Build we will be creating a good base map for a B20 vtec that can be used for others to work from.
Now i have had a quick session with a well known Tuning GURU and even in that quick sesion we made some differences to the map that were very noticable and have given me a lot more drivabilty.
Since the basic Building of the engine I have added the following,
Custom Heat wrapped 4-1 manifold, Custom 2.5" exhaust system with as much flow and as little restricions as possible,
This particular system was a 2" prototype version I have now adjusted it slightly and am using 2.5" id piping which has made a noticable difference,
this particular system goes under the fuel tank not around and over the rear arms, its not so good on the road as its low but for my track car its fine.
I have also added a Custom Heat wrapped intake pipe and bigger filter, so far these simple mods have made a difference on the way the vehicle drives it has alot more throttle response and pulls from lower down and revs higher easier.
The 2nd B20Vtec build was for a friend, but i had say in the build,
B20z bottom end
B18C4 skimmed head
ARP head studs
KMS block gaurd
GE B20 kit
B18 crank girdle, windage tray anmd sump
70mm STR Throttle body
2.5" under tank exhaust
custom 4-2-1 manifold
The car made 221bhp and 156ft/lbs.
My current B20 is a B20b with a similar spec to above but using a B20B bottom end, B16 head with alot of head wprk and Buddy club cams.
180WHP and 156ft/lbs
PROBLEMS WITH MY B20
Yes there have been some teething problems.
The biggest problem i have been having is PCV related i have been getting serious Crank case pressure and was blowing out oil seals left, right and centre at the start.
I have adpted the PCV system on my car and with trial and error i have managed to stop the oil seal issue I am still getting excessive pressure build up and am filling up a 1litre catch can every 3/4 days.
Now i have designed and built a new catch can and have had some bigger fittings and pipe made up for me, I am hoping that this will stop my problems, If we are still getting problems I can only put it down to the to blowing by on the piston rings which is pressurising the crank case.
It turns out that over time and testing various methods we found the culprit of why the catch can was filling up, I have edited this further up the page to help,
Basicly the 2 fittings on the back of the block are to much and are causing a suction which is puling oil out of the left had fitting, This port is actually the return gallery from the head, I put the original fitting back in and its been sweet.
Now the above problem has only affected My self I have not heard of any other B20 that have had this problem.
Other than the above named PCV problem the only other thing is TRACTION B20vtec's tend to like wheel spining and its the low revs at which it spins at is amazing at the torque difference, 2500 rpm and mine just starts spining even on very good tyres at 26psi. its crazy.
I hope this write has been help full.
And I am hoping there wont be a Part5 (engine blown up B20 for sale lol)