B18/B20 vtec discussion
08-May-2010, 07:24 PM
#1
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B18/B20 vtec discussion
So I figured this could benefit a lot of people (me included).
I have been doing a lot of research about this and its hard to find decent unbiased information. So anybody with better knowledge please chime in. And please don't jump the bandwagon saying its crap or its the best with no explanation. Please provide some information to back up your opinion/theory.
This this is what I have learned so far. As many people say the rod/stroke ratio is not optimal in B20/b18 but revving to 7500/8000rpm would that really be affected that much? Though both blocks don't have oil squirters as the vtec B-series motors, I doubt it would cause much harm since its only a bit over stock rev limit.
Also, choices of which head to use, I came to conclussion that the b18c1 (gsr) would probably be slightly better since vtec engagement is earlier than b16 and it would eliminate the need to rev that high. Someone may say you can change engagement of vtec to where ever one may prefer, but I'm sure Honda designed it this way for a reason.
Other mods would include gsr/b16 water pump/timing belt/oil pump, since iirc vtec oil pumps flow a bit more correct? Ofcourse oil lines for the head. Any other mods would be needed?
Oh and I guess I should mention this, I'm thinking of doing this on a B20b block. Reason I haven't done this yet because I hear many horror stories from idiots who push the motors to 9000+ rpm with a crappy tune and complain that rods fly out. So any information relative to this thread would be greatly appreciated.
Martin
I have been doing a lot of research about this and its hard to find decent unbiased information. So anybody with better knowledge please chime in. And please don't jump the bandwagon saying its crap or its the best with no explanation. Please provide some information to back up your opinion/theory.
This this is what I have learned so far. As many people say the rod/stroke ratio is not optimal in B20/b18 but revving to 7500/8000rpm would that really be affected that much? Though both blocks don't have oil squirters as the vtec B-series motors, I doubt it would cause much harm since its only a bit over stock rev limit.
Also, choices of which head to use, I came to conclussion that the b18c1 (gsr) would probably be slightly better since vtec engagement is earlier than b16 and it would eliminate the need to rev that high. Someone may say you can change engagement of vtec to where ever one may prefer, but I'm sure Honda designed it this way for a reason.
Other mods would include gsr/b16 water pump/timing belt/oil pump, since iirc vtec oil pumps flow a bit more correct? Ofcourse oil lines for the head. Any other mods would be needed?
Oh and I guess I should mention this, I'm thinking of doing this on a B20b block. Reason I haven't done this yet because I hear many horror stories from idiots who push the motors to 9000+ rpm with a crappy tune and complain that rods fly out. So any information relative to this thread would be greatly appreciated.
Martin
10-May-2010, 10:39 AM
#2
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^^Glad you started this thread, Martin. 
I recently bought an ls (b18b1) engine for $140 (complete block/head, no intake, exhaust mani's, no flywheel/crank pulley). Engine came out of a teg running fine, owner swapped in a stock b20.
I too have been reading up like crazy and speaking to a lot of knowledgable people on the subject. I'll try to address as many things as I can remember in the next post.
My dilemma right now is whether to build it for NA all-motor hp or do the basic vtec conversion and boost it...? For the same cost you could build a 200whp NA monstor or a 300+whp turbo beast...
The possibilities are endless!!! lol
I recently bought an ls (b18b1) engine for $140 (complete block/head, no intake, exhaust mani's, no flywheel/crank pulley). Engine came out of a teg running fine, owner swapped in a stock b20.
I too have been reading up like crazy and speaking to a lot of knowledgable people on the subject. I'll try to address as many things as I can remember in the next post.
My dilemma right now is whether to build it for NA all-motor hp or do the basic vtec conversion and boost it...? For the same cost you could build a 200whp NA monstor or a 300+whp turbo beast...
The possibilities are endless!!! lol
10-May-2010, 12:45 PM
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First off, www.c-speedracing.com is an excellent source of info, DIY instructions for the ls/b20 vtec builds/info as well as other very helpful data. They have a compression calculator where you can select your engine components and it will tell you how much compression it will have. They also have a fully-detailed DIY instruction for a basic ls/b20 vtec conversion.
The following is a simplification/generalization of some of the info I've gathered with regards to ls/b20 vtec conversions/builds.
Couple things to note which Martin already mentioned: Both the b20 and b18a/b blocks DO NOT have the under piston oil squirters as the vtec blocks come standard with (b16a/b18c1/c5 etc...). They CAN be added, but some careful machining is required. Most ls/b20 vtec builds, even the ones that make some big numbers, do not have the squirters, but they can get away with this by using forged aftermarket pistons made with better materials which can handle the heat much better then the stock oem pistons.
While b20's have a larger displacement then the b18's, there are several positives and negatives to both engines. One issue with the b20 is the thinner cylinder walls due to the larger bore (84mm). Don't get me wrong, some big numbers can be put down with the b20, but if you're planning on building a high-pressure boosted race motor, you may want to consider the b18 block instead. The b20 can be made to make a lot of power, but it is more logical to build it for NA or lower-pressure boost. The b20 with it's larger bore also leaves only 2 options when deciding on which pistons to use. You can either use the stock oem b20 pistons which will have a lower cr (compression ratio) and power limit, or you must go aftermarket for a higher compression and/or forged units. Since the b18 shares the same 81mm cylinder bore as all the other b-series dohc vtec engines, you can use any honda oem vtec piston to raise compression, make and handle more power and keep the cost down. Civic type-r (b16b) pistons are a good choice for building NA motors with their high compression and special friction-reducing coating. Another plus for the b18 is it's thicker cylinder walls. If you want to build your motor for high boost, this is the block for you.
Cylinder Head choices: You can use ANY b-series dohc vtec head for the conversion. The b16a and b18c5 heads are almost identical with the exception of the c5 head having some slight p&p work from the factory (or so I've heard). The b18c1 (gsr) head will yield slightly higher compression due to it's slightly different combustion chamber design (google image to see the difference). The same compression can be achived with the b16/b18c5 head by shaving or milling some material off the head, but care should be taken when doing so as depending on the cam shaft and piston selection, there could be some issues with valve to piston clearance. APR head bolts must be used for dohc b-series vtec heads.
Cams: Any b-series vtec cam can be used, though don't expect huge hp numbers. They are ideal for boost applications though. The type of cam to use will be reflected by how much power you want to make and by what terms (NA for FI). With any cam upgrade, aftermarket double valve springs and chromally or titamium retainers should be used. You'll also want to check if your valve seats, seals, guides are in good condition or need replacing. A valve job is also a good idea, while you have everything appart. Adjustable cam gears is also necessary for dialing in the proper valve timing.
The Bottom end: It is a good idea to balance the rotating assembly, even if yu are planning on keeping it under 8000rpm. It will help it run smoother and make it that much more reliable should it accidentally turn a little quicker...lol. It is a MUST to have everything balanced if you plan on building a high-hp, high rpm NA screamer. Just common sense. The B18c1/5's come from the factory with main bearing crank girdles. (piece that joins the 3 center bearings to create a stronger ladder-frame to reduce torsional stress, vibration and deformation. I believe (not 100% sure on this) that it is possible to use those crank girdles on the ls (b18a/b) block. It is not possible to use with the b20 due to the larger stroke, but might be possible after some modification and machine work to the girdle. As long as stronger APR hardware is used (main bearing/rod bolts), higher rpms with the stock crank and rods is perfectly do-able (as long as it is balanced as discussed earlier). Some pistons require some minor machine work to the oem rods to work. Nother major or super expensive, just a bit of material shaved off each side where the wrist-pin goes. You'll want to check if your chosen piston type will require this procedure. And of course if your looking pumping out some serious huge ponies, aftermarket/forged rods may be necessary. The factory rods can only take so much.
Timing belt, water and oil pump: It's necessary to use a gsr or b16 timing belt, water and oil pump. The water and oil pumps from the vtec engines are stronger and more efficient, from what I have read/heard.
There are kits available that have everything you need to do the basic vtec conversion. They usually consist of oil lines for feeding the vtec system, head gasket (usually for 84mm to accomedate the larger bore of the b20 engine, or some kits you can specify which gasket you want...), special dowel pins that illiminate the requirement to drill the head to re-locate the dowels. Some kits even come with APR head bolts.
Could go on, but I'll leave it at that for now...lol
Any questions, thoughts?
The following is a simplification/generalization of some of the info I've gathered with regards to ls/b20 vtec conversions/builds.
Couple things to note which Martin already mentioned: Both the b20 and b18a/b blocks DO NOT have the under piston oil squirters as the vtec blocks come standard with (b16a/b18c1/c5 etc...). They CAN be added, but some careful machining is required. Most ls/b20 vtec builds, even the ones that make some big numbers, do not have the squirters, but they can get away with this by using forged aftermarket pistons made with better materials which can handle the heat much better then the stock oem pistons.
While b20's have a larger displacement then the b18's, there are several positives and negatives to both engines. One issue with the b20 is the thinner cylinder walls due to the larger bore (84mm). Don't get me wrong, some big numbers can be put down with the b20, but if you're planning on building a high-pressure boosted race motor, you may want to consider the b18 block instead. The b20 can be made to make a lot of power, but it is more logical to build it for NA or lower-pressure boost. The b20 with it's larger bore also leaves only 2 options when deciding on which pistons to use. You can either use the stock oem b20 pistons which will have a lower cr (compression ratio) and power limit, or you must go aftermarket for a higher compression and/or forged units. Since the b18 shares the same 81mm cylinder bore as all the other b-series dohc vtec engines, you can use any honda oem vtec piston to raise compression, make and handle more power and keep the cost down. Civic type-r (b16b) pistons are a good choice for building NA motors with their high compression and special friction-reducing coating. Another plus for the b18 is it's thicker cylinder walls. If you want to build your motor for high boost, this is the block for you.
Cylinder Head choices: You can use ANY b-series dohc vtec head for the conversion. The b16a and b18c5 heads are almost identical with the exception of the c5 head having some slight p&p work from the factory (or so I've heard). The b18c1 (gsr) head will yield slightly higher compression due to it's slightly different combustion chamber design (google image to see the difference). The same compression can be achived with the b16/b18c5 head by shaving or milling some material off the head, but care should be taken when doing so as depending on the cam shaft and piston selection, there could be some issues with valve to piston clearance. APR head bolts must be used for dohc b-series vtec heads.
Cams: Any b-series vtec cam can be used, though don't expect huge hp numbers. They are ideal for boost applications though. The type of cam to use will be reflected by how much power you want to make and by what terms (NA for FI). With any cam upgrade, aftermarket double valve springs and chromally or titamium retainers should be used. You'll also want to check if your valve seats, seals, guides are in good condition or need replacing. A valve job is also a good idea, while you have everything appart. Adjustable cam gears is also necessary for dialing in the proper valve timing.
The Bottom end: It is a good idea to balance the rotating assembly, even if yu are planning on keeping it under 8000rpm. It will help it run smoother and make it that much more reliable should it accidentally turn a little quicker...lol. It is a MUST to have everything balanced if you plan on building a high-hp, high rpm NA screamer. Just common sense. The B18c1/5's come from the factory with main bearing crank girdles. (piece that joins the 3 center bearings to create a stronger ladder-frame to reduce torsional stress, vibration and deformation. I believe (not 100% sure on this) that it is possible to use those crank girdles on the ls (b18a/b) block. It is not possible to use with the b20 due to the larger stroke, but might be possible after some modification and machine work to the girdle. As long as stronger APR hardware is used (main bearing/rod bolts), higher rpms with the stock crank and rods is perfectly do-able (as long as it is balanced as discussed earlier). Some pistons require some minor machine work to the oem rods to work. Nother major or super expensive, just a bit of material shaved off each side where the wrist-pin goes. You'll want to check if your chosen piston type will require this procedure. And of course if your looking pumping out some serious huge ponies, aftermarket/forged rods may be necessary. The factory rods can only take so much.
Timing belt, water and oil pump: It's necessary to use a gsr or b16 timing belt, water and oil pump. The water and oil pumps from the vtec engines are stronger and more efficient, from what I have read/heard.
There are kits available that have everything you need to do the basic vtec conversion. They usually consist of oil lines for feeding the vtec system, head gasket (usually for 84mm to accomedate the larger bore of the b20 engine, or some kits you can specify which gasket you want...), special dowel pins that illiminate the requirement to drill the head to re-locate the dowels. Some kits even come with APR head bolts.
Could go on, but I'll leave it at that for now...lol
Any questions, thoughts?
11-May-2010, 01:38 AM
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Mike, thanks for that. A LOT of information I was looking for.
Now the problem is, I don't want to spend all that much money. I was thinking about replacing rod bolts/head bolts/oil/water pumps.
As you stated, girdle will be problematic for the B20. Also oil squirters for going another 1000rpm over stock I don't think will cause many problems if its not a track car. I know it sounds like I'm trying to cut corners, but due to my situation I doubt I will need this for long. A year tops.
Now the problem is, I don't want to spend all that much money. I was thinking about replacing rod bolts/head bolts/oil/water pumps.
As you stated, girdle will be problematic for the B20. Also oil squirters for going another 1000rpm over stock I don't think will cause many problems if its not a track car. I know it sounds like I'm trying to cut corners, but due to my situation I doubt I will need this for long. A year tops.
11-May-2010, 01:48 AM
#6
the stock rev limit for a b20 is like 6000-6500rpms and for the LS is 7200rpms.
I just tuned one tonight that made 180whp 142wtq. It was a stock B20 block with a stock GSR head with a skunk2 pro series intake manifold, short-ram intake, cheap header with 2.5" collector and 2.5" exhaust with a cat.
I just tuned one tonight that made 180whp 142wtq. It was a stock B20 block with a stock GSR head with a skunk2 pro series intake manifold, short-ram intake, cheap header with 2.5" collector and 2.5" exhaust with a cat.
11-May-2010, 03:17 PM
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^^ There are some dyno sheet's on his website. Not sure, but that motor may be one of them...
If you're going to rev it past the stock limiter, it's a good idea to have the rotating assembly balanced.
If you're going to rev it past the stock limiter, it's a good idea to have the rotating assembly balanced.
11-May-2010, 05:28 PM
#9
the rev limit was set to 8000rpms. The dyno sheet from that one isn't on my website, I just tuned that car last nite and haven't updated my website in over a year. I have a million dyno sheets to add to my website, but no time to do so.
12-May-2010, 01:56 AM
#11
That the highest I would go if it was my car.
The head can take that no problem, but due to the 84mm bore X 89mm stroke of the b20 its not as stable at higher rpms and the LS/B20 engines lack the crank girdle that the GSR/ITR has.
This one had a skunk2 intake manifold so the power carried up to 8000rpms, typically with a stock GSR intake manifold and stock b16 intake manifold typically the power will peak and start to drop at 7500-7800rpms, so if you wanna be real safe 7500-7800rpms would suffice.
The head can take that no problem, but due to the 84mm bore X 89mm stroke of the b20 its not as stable at higher rpms and the LS/B20 engines lack the crank girdle that the GSR/ITR has.
This one had a skunk2 intake manifold so the power carried up to 8000rpms, typically with a stock GSR intake manifold and stock b16 intake manifold typically the power will peak and start to drop at 7500-7800rpms, so if you wanna be real safe 7500-7800rpms would suffice.
01-Jun-2010, 04:45 AM
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So after some more research and a purchase I'm starting my build.
I picked up another B20b block with a b16a 1st gen head. My plans now are to check the bearing clearance and possibly order new ones. Also new rings for the stock pistons. That will be bolted up with arp bolts.
For the head, get it milled (not sure how much but just slightly), p&p, thinking about gsr cams since I wanted to use a gsr head but due to the price I couldn't pass this on.
New timing belt, water pump and oil pump will be added to the list. Also skunk2 intake manifold with a 60mm or 70mm throttle body. All new gaskets and seals including crank/cam/oil pan/valve cover and few others. A stage 2 clutch and a light weight flywheel.
Without going past 7800-8000rpms I'm hoping for 175-180whp mark.
Ill have pics once bellhousing bolts come in so I could put the block up on a stand.
I picked up another B20b block with a b16a 1st gen head. My plans now are to check the bearing clearance and possibly order new ones. Also new rings for the stock pistons. That will be bolted up with arp bolts.
For the head, get it milled (not sure how much but just slightly), p&p, thinking about gsr cams since I wanted to use a gsr head but due to the price I couldn't pass this on.
New timing belt, water pump and oil pump will be added to the list. Also skunk2 intake manifold with a 60mm or 70mm throttle body. All new gaskets and seals including crank/cam/oil pan/valve cover and few others. A stage 2 clutch and a light weight flywheel.
Without going past 7800-8000rpms I'm hoping for 175-180whp mark.
Ill have pics once bellhousing bolts come in so I could put the block up on a stand.
01-Jun-2010, 09:06 AM
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^^Sounds good, Martin!
Now we have 2 hybrid honda motor builds on the go! Sweet! You'll have to start a build thread in the media section and get some pic up asap!
Just got my whole engine fully diss-assembled on sunday... pricing out all new bearings and ARP hardware.
On c-speedracing.com they have a compression calculator where you can input your specific setup and then play around with milling the head to see what kind of compression you'll get.
Cool stuff!
Now we have 2 hybrid honda motor builds on the go! Sweet! You'll have to start a build thread in the media section and get some pic up asap!
Just got my whole engine fully diss-assembled on sunday... pricing out all new bearings and ARP hardware.
On c-speedracing.com they have a compression calculator where you can input your specific setup and then play around with milling the head to see what kind of compression you'll get.
Cool stuff!
01-Jun-2010, 03:53 PM
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Here is a question, what bearings will you be using? I was looking at ACL duraglide or race but the fact that there is no real selection of sizes kind of throws me off.
And thanks Mike, it will start once I get my camera back (tomorrow).
And thanks Mike, it will start once I get my camera back (tomorrow).
01-Jun-2010, 04:09 PM
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I'm going to use the standard ACL oem replacement bearings (oem spec, non-oversized) and plastigauge it. Same for the rods.
I heard the race bearings are a little looser...don't really want that. lol.
Also looking at where to get new oem piston rings...
Looking at my bearings, seems there may have been a little detonation at one point... Otherwise, they look pretty good. No excessive wear. Means the oem bearings should be just fine.
One website I found there is a colour code according to the number stamped on the side of the rod/cap and the markings on the block to determine which rod bearings to use. See link:
Honda Main & Rod Bearing Color Codes - Team Integra
Last edited by MPR; 01-Jun-2010 at 04:12 PM.
01-Jun-2010, 09:37 PM
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Here is another question.
Using a B20b block, I could swap B20z phr pistons. According to the compression calculator, with stock head not milled, that should put me around 9.9:1 cr. Would that be enough clearance if I used a gsr cam? Now I don't know this for a fact but I believe gsr cams have longer duration than b16? I could just order the pistons and clay it to check, but don't want to waste money.
Any help will be appreciated.
Using a B20b block, I could swap B20z phr pistons. According to the compression calculator, with stock head not milled, that should put me around 9.9:1 cr. Would that be enough clearance if I used a gsr cam? Now I don't know this for a fact but I believe gsr cams have longer duration than b16? I could just order the pistons and clay it to check, but don't want to waste money.
Any help will be appreciated.
