opinions

[1813mdw]

i have an extra head layin around that i plan on cleanin up and doing a mild port and polish. eventually i plan on a small(K-car) turbo. now, do you guys think it would be worth the hassle and $ to get oversized valves? i do not care about hp at all; torque is all i am after. i dont think it would be vital but am not sure

[stephensimmons]

i have an extra head layin around that i plan on cleanin up and doing a mild port and polish. eventually i plan on a small(K-car) turbo. now, do you guys think it would be worth the hassle and $ to get oversized valves? i do not care about hp at all; torque is all i am after. i dont think it would be vital but am not sure

If you want more torqe then read this thread.

http://www.3geez.com/forum/showthread.php?t=71854&page=2

as for the oversized valves read this.

http://www.3geez.com/forum/showthread.php?t=71755

and as for porting read this

http://www.3geez.com/forum/showthread.php?t=72391&page=2

Hope this helps you atleast a little!

[89T]

If you are going through the trouble, get a B18a/B intake manifold and gasket and port match to that gasket. Not to the a20 gasket.

[1813mdw]

If you want more torqe then read this thread.

http://www.3geez.com/forum/showthread.php?t=71854&page=2

as for the oversized valves read this.

http://www.3geez.com/forum/showthread.php?t=71755

and as for porting read this

http://www.3geez.com/forum/showthread.php?t=72391&page=2

Hope this helps you atleast a little!


thanks for the links, man. really i was looking for some opinions on how important it is to make our restrictive 12valve heads to flow with boost. i don't think i will need to get oversized valves for decent low to midrange torque. but i've also never built a honda motor either. also, is 250-300trq a reasonable goal?

[1813mdw]

If you are going through the trouble, get a B18a/B intake manifold and gasket and port match to that gasket. Not to the a20 gasket.

aren't our longer runners better for trq? i planned on port matching an a20 im that i also got as a spare with the car. i'll keep searching; but all opinions are appreciated:)

[89T]

look at the skunk2 im's.. nice long runners.

[stephensimmons]

aren't our longer runners better for trq? i planned on port matching an a20 im that i also got as a spare with the car. i'll keep searching; but all opinions are appreciated:)

They are longer but also smaller in diameter so it dont flow as well.

[Hauntd ca3]

if you plan on going turbo later, the short and fat or long and thin runner bit dosnt really matter to much.
just go for the b16a inlet mani.
the a20 and b20a make pretty decent bottom end torque anyway once you stick a 2.25 or 2.5 inch exhaust on them.

[1813mdw]

thanks guys. i'll def look into skunk2 ims. my main concern is the head right now, as that will prob be the most pricey(besides turbo setup itself). what about ovrsized valves? waste of money w/turbo? what kinda trq #s are you turbo guys runnin?

[1813mdw]

any input, guys?

[rjudgey]

Well personally if you are going to run a turbo setup and are after torque i would be more concerned about quality of port reshaping, and quality of valve seat cutting and valve head matching. This out of all will give you the most for the least amount of work and if not done right will really make your engine run like a dog!
Personally if running a turbo setup i would be inclined to ditch the steel valves on the inlet side and go with stainless steel ones and if you are going to that effort to change them might as well go up 1.5-2mm in size. Exhaust valve is a excellent quality but on turbo engine it's well worth increasing the size, here might be where you could so some work with taking your old exhaust valves, finding another set have them machined a inlets and then have 4 SI valves madeup at 37mm. Use SI bronze guides cheap as chips and won't wear out as quickly as the stock cast iron ones.
Make sure that the chambers are deshrouded around the valves, the roof is polished flush with the seats, and that they are all capacity matched the same. Important not to take toomuch off the head here as you don't want your CR ratio increasing too much more but if you need to just take a little more out of the chamber and match the chamber walls to the bore walls on the block. Just remember to make sure the chamber CC's are all the same again! As for the valve seats it's much better to have a really big bottom cut at 60 degrees, for seat widths go with 1.25mm on inlets for turbo and 1.5mm exhaust width, for non turbo 1mm all round is perfect, having radiused valve seat cuts is best but only a few top head places will be able to do this. If you don't have this option you can do this a little bit yourself by just carefully rubbing across the sharp angles with a piece of wet and dry something like 1500-2000 grit nothing harsh! Just to smooth off the sharp angles! Sounds like being anal but trust me it's all the little details that you do that add up to a big gain when you get it all tuned up!! There's a reason why my basic engines make 200 plus bhp with just Weber carbs and it's the level of detail i go into on the heads!!

[Vanilla Sky]

I'm planning on running a b16 IM on my challenge car. I hope to do some head porting, but it depends on whether I can budget in the gasket kit for it. I'm planning on running turbo, but I'm very budget constrained.

[1813mdw]

Well personally if you are going to run a turbo setup and are after torque i would be more concerned about quality of port reshaping, and quality of valve seat cutting and valve head matching. This out of all will give you the most for the least amount of work and if not done right will really make your engine run like a dog!
Personally if running a turbo setup i would be inclined to ditch the steel valves on the inlet side and go with stainless steel ones and if you are going to that effort to change them might as well go up 1.5-2mm in size. Exhaust valve is a excellent quality but on turbo engine it's well worth increasing the size, here might be where you could so some work with taking your old exhaust valves, finding another set have them machined a inlets and then have 4 SI valves madeup at 37mm. Use SI bronze guides cheap as chips and won't wear out as quickly as the stock cast iron ones.
Make sure that the chambers are deshrouded around the valves, the roof is polished flush with the seats, and that they are all capacity matched the same. Important not to take toomuch off the head here as you don't want your CR ratio increasing too much more but if you need to just take a little more out of the chamber and match the chamber walls to the bore walls on the block. Just remember to make sure the chamber CC's are all the same again! As for the valve seats it's much better to have a really big bottom cut at 60 degrees, for seat widths go with 1.25mm on inlets for turbo and 1.5mm exhaust width, for non turbo 1mm all round is perfect, having radiused valve seat cuts is best but only a few top head places will be able to do this. If you don't have this option you can do this a little bit yourself by just carefully rubbing across the sharp angles with a piece of wet and dry something like 1500-2000 grit nothing harsh! Just to smooth off the sharp angles! Sounds like being anal but trust me it's all the little details that you do that add up to a big gain when you get it all tuned up!! There's a reason why my basic engines make 200 plus bhp with just Weber carbs and it's the level of detail i go into on the heads!!


thank you very much, sir. just the kind of input i was looking for.

[1813mdw]

I'm planning on running a b16 IM on my challenge car. I hope to do some head porting, but it depends on whether I can budget in the gasket kit for it. I'm planning on running turbo, but I'm very budget constrained.

have you messed around w/ the stock im before? thats what i'm gonna do first as i have an extra to expiriment with. i think they have a lot of potential for a broad powerband; which is what i'm looking for. as for the turbo what were you thinking? i'm thinking of a 14b dsm(dirt cheap, fairly reliable, and spool up quickly) w/ a rebuild.

[LiTtLe xOx BitT]

You can use a modified B18 or B16 intake manifold. Also you can use ARP head studs for a 2.0l mazda miata, a lot stronger then the stock honda ones and good for boost. Not sure on what PSI your plan to run but if your thinking of a higher PSI then they would be a good upgrade. You could also use a T3/T4 turbo, pretty small, not too expensive and spools up pretty fast.

[1813mdw]

what exactly are the benefits of a ramhorn mani as opposed to a log manifold?

[gp02a0083]

what exactly are the benefits of a ramhorn mani as opposed to a log manifold?


i would assume that there would be less lag. I would assume that the ram horn style would allow a higher flow velocity rather than a log type which is essentially a baffle