Boosting basics

Turbocharging, Supercharging, Intercooling, etc.

Moderators: RedRacer, Moderators

cucurumbe
Lude Dude
Posts: 32
Joined: Sun Feb 15, 2009 9:55 am

Boosting basics

Postby cucurumbe » Sun Nov 15, 2009 12:09 pm

OK everyone is talking about forced induction and I didn't want to go that route because NA is, well , natural. But " suppose" I did want to turbo my lude.Which motor is better for boost, the b21 or the b20? I was originally going to build a b21 with a b20 head , but I have heard the b20 is better under boost than the b21. Is this true? Should I keep my b20 and boost it or can I build the motor as i want and boost it?

User avatar
spiffyguido
Moderator
Posts: 2196
Joined: Fri Nov 11, 2005 2:55 am
Prelude Model: 1991 SE-SR
Location: Alberta, Canada
Contact:

Re: Boosting basics

Postby spiffyguido » Sun Nov 15, 2009 3:32 pm

I can see reasons to go with either engine:

People likely feel that the B20A5 is the right engine to boost because they are afraid of the B21A1s problems with cylinder rings. I see this argument as being invalid. Yes, the FRM material in the cylinder walls of the B21 is hard on cylinder rings, but in return you get much stronger cylinder walls. Another thing that the B20A5 has going for it is that it is much easier to find, so if you're needing to source parts from wreckers, you're going to have a much easier time finding things for the B20A5.

The B21 has its advantages as well. The FRM cylinder walls are incredibly strong, so they should do better than the B20A5's metal cylinder walls under boost. The B21 also has better displacement, which always helps. They are, however, harder to find. They are also an OBD1 engine, which makes them much easier to tune.

I'm currently (slowly) working on a forced induction project myself. I got a B20A5 to build up, mainly because it was easier to find a good one. If I could get the parts, I would choose to use a B21 engine with a B20 head on it. The B20 head has a smaller bore than the B21, so when the B20 head is on the B21 you get a wicked squish zone. I would use the ECU from the B21 and would use the B21 intake manifold.

In short, I don't think there are huge advantages either way. At the end of the day, they're both good engines and can be boosted. Everything comes down to the tune. Both engines are capable of putting out some good power. I'd go with whatever setup gives you the highest probability of getting the results you want at a reasonable cost.

cucurumbe
Lude Dude
Posts: 32
Joined: Sun Feb 15, 2009 9:55 am

Re: Boosting basics

Postby cucurumbe » Sun Nov 15, 2009 6:33 pm

Great info spiff. I think I will go with the b21 with a b20 head on it. I have been hearing about the piston ring problem and an oil burning problem which I think are one in the same. Are these the only major cons to our motors because I keep hearing about the reliability of these motors.
Now I would like to ask some questions on this ring problem . I know you say oem is the best and I have no problem with that. How do you side step this problem? Are there better rings out there? Do you just not push the motor? Proper tuning of course is essential when the boosting is involved.I understand that. Does proper tuning and respect for your motor remove this possibility? As always thank you in advance.
That was easy!!

User avatar
spiffyguido
Moderator
Posts: 2196
Joined: Fri Nov 11, 2005 2:55 am
Prelude Model: 1991 SE-SR
Location: Alberta, Canada
Contact:

Re: Boosting basics

Postby spiffyguido » Sun Nov 15, 2009 7:04 pm

The engines don't have any serious reliability problems.

Besides the issue with the rings, the only other issue that I know of is that the #3 crank journal can get starved for oil at really high rpm. This, I suspect, is due to the design of the oil channels in the engine girdle. Not stuff you can try to fix, but not a big issue either. If the engine is being held at really high rpm (>5000 rpm) for long periods of time, I can see this being an issue, but who really drives like that anyway? Anytime you rev an engine high for long periods you're asking for some sort of trouble.

The problem with the rings is not due to the rings themselves. In fact, I would not suggest any other ring other than the OEM Honda ones. Honda stuff is superb quality, and the OEM rings are VERY good. Use them. The source of the problem is the FRM cylinder walls which is very hard and therefore abrasive on the software piston rings. I'm sure that Honda was aware that this would happen. Though people don't realize it, changing piston rings isn't that big a deal, so Honda probably felt that by putting FRM in the cylinder walls they were offering a better end product. My B21 has 170000 kms on it, original rings, and it's fine. If you beat on the car, or don't maintain it, then I'm sure they would fail sooner, but that's true for anything. If my rings go bad, I'll just switch them out. As far as messing with parts inside the engine, it's probably the easiest thing to do.

So, to answer you questions: You can't sidestep the problem, the Honda rings are great, and you should never push a motor too hard in the first place.

Proper tuning and respect for an engine always helps. People always under estimate how much good simple things like regular oil changes actually do for an engine.




Return to “Forced Induction”

Who is online

Users browsing this forum: No registered users and 1 guest