What are the major limits to a b20 block that will live a sad naturally aspirated life? I was planning on finishing up my ls/vtec for my future auto-x hatch, but even with budget constraints I know I won't realisticly build one that'll put out more than 180 to the wheels. So in the n/a form where displacement is king, what are the weaker points to these blocks? The plan is for stock rods/arp rod bolts and cast pistons (you know those nice type-r 84mm clones) to keep cost to a minimum, and the typical b16 head with a cam swap and a decent p&p job. Valvetrain will more or less be a limiting factor to higher than stock rpm, so I'll probably upgrade that as well but I'd like to be able to see a realistic 9500 limit. Gimme the goods...I know at least Chris and JD have some info on these

 

well if i were you i would have the rotating assembly balanced to a ------- T.

other than that it sounds like a good build. b20 block are gangster NA blocks there are just shitty boostin motors

 

http://crx.honda-perf.org/articles/crvtec/crvtec.html




Budget wise that is a great choice. b20z pistons should be able to be found for very cheap used



Your goal of 9500 takes away the cheap part. Your looking at atleast itr cams,valvetrain upgrades and opening up the bottom end




That article is a solid oldie but goodie to what a simple set up does and will perform well. The b20vtecs I have driven in were really fun. Very similar to the locash build and with the price of jdm b20 blocks these days and the fact that the are newer low mileage blocks no maching should be needed

 

i doubt ITR cams will get you to 9500, i think you'd need something a little more extreme. But with a redline that high, it seems like you'd be killing the appeal of using the b20...

 

That's pretty much what I was thinking too. Bottom end's are usually balanced pretty well from the honda factory, but the valvetrain will be the killer, especially for a semi-budget based build. Dual springs and retainers are more than likely going to be a must, was looking at the rocket or omni lines for them. Cams are hard to justify although unfortunately necessary to make a few extra...spending $500 just to make 12-15hp seems like such a waste :P
Thanks for the link Chris!

 

your going to take out the pistons to change the rod bolts why wouldnt you just have everything balanced while it all apart. it cost like $100. why wouldnt you want to be on the safe side ?

 

itr intake cam dude thats all you need. 9500 can be achieved with good power up top but you will need a cylinder head that flows in the 300 cfm range w/ itr cam combo

 

I would have the rods balanced to the pistons as best as possible, maybe to the crank depending on the price. No matter what route I go it's going to be more expensive than a turbo setup, but at least with n/a I can (A) stay in a lower class, and (B) not have to deal with all these stupid issues that I've been having lately. I'm getting sick and tired of my car overheating on a daily basis, having exhaust leaks from brand new gaskets every week, etc. At least with a b20 block I can reach over that 200hp mark where EF's are quick and fun and have to deal with less issues.
I think with some decent porting action I should be able to get 300cfm through the head.

 

300 cfm from a b series head cant be done without a flowbench its the truth. The typical head will be in the 265-275 range basically 10 whp gain which is common




300 cfm head would require some real skill and flowbench time for sure




The key is not to loss velocity has well.

 

I used to port D-series a6 heads and a few gsr heads at my old race shop. I still have access to the flow bench so I should be able to run results before and after with no issues. Biggest thing I've found on port velocity is not so much in opening them up like most ameteurs tend to do, but cleaning up the casting...around the bowls especially and never try to knife edge the splitter. It just ends up hurting velocity in the long run and since the airflow is mostly confined to the walls of the port, the edge can act like an airfoil if done properly...forcing the air to move faster around it.