Natural Aspirations

I know it's been proven time and time again turbo cams are not ideal in Honda motors, why is that? In theory you want a bunch of lift and little overlap. Sometimes theory isn't what it is cracked up to be.

rev-speed

i say it has to do with how good our heads flow

Garage 808 Hatch

most of the turbo camshafts offered (that I've looked at) are not all that big in reference to measurements. Skunk 2 turbo2 B cams, the intakes are actually smaller than GSR stock cams, the exhaust cams is .024" more lift, same duration.

sethm

hmm

ironcheftony

imo, most turbo cam's are for motors that come with turbo stock, which helps in their performance

DeLucia

For best driveability and power go with ITR cams.

Natural Aspirations

For referece sake let us take 2 examples, to make it as simple as possible we will use a b18b engine and crower cams and an 8k redline everything equal 300hp goal which will make more power over the curve.


62403T-2
In 190 deg @ 0.050" opens -14 BTDC closes 24 ABDC
Ex 190 deg @ 0.050" opens 32 BBDC closes -22 ATDC
LSA 113 deg

62405A-2
In 241 deg @ 0.50" opens 16 BTDC closes 46 ABDC
Ex 238 deg @ 0.50" opens 52 BBDC closes 6 ATDC
LSA 109 deg

While theses two cams have "similar" maximum lift the cam timing properties are entirely different. Can the overlap and duration on the 62405a be used as an advantage and any excess be tuned out with cam gears?

I realize this leaves a lot out such as turbine housings and manifold choices but I am trying to keep the discussion directly on the camshaft tuning.

Natural Aspirations

No bites?

00Red_SiR

I don't think this section focuses on cams quite like we did in the AM section which is probably why there aren't any bites. Ironically I found myself wondering the same thing and started searching various builds and the cams they used, looking for answers. Mostly what I found was that everyone used the same 2-3 different types of camshafts in their builds so I don't think many have done the testing that would answer your/our question(s)?

I was thinking that if you had two similar sets of cams, 1 set having higher lift and less duration and the other set being just the opposite. If you could dial out excessive overlap, I would think they would have very similar curves.

Dueceification

I think one issue why people dont buy turbo cams is with the money for the cams you can pick a better turbo or manifold when starting off which generally gives you better gains.

0KStuned

The right camshaft really depends on what your exhaust manifold/turbine housing/turbine wheel size is. Very generally speaking, Type R cams will allow you a lot of wiggle room and provide gains almost everywhere.

For example, I wouldn't recommend Pro 1 camshafts to someone with a cast manifold and a .48 a/r T3 turbine

Just remember try to decrease the valve overlap for a small turbine housing or an exhaust manifold that doesn't flow very well.

Even if you can't measure the exact cam centerlines, if you advance the exhaust and retard the intake a few degrees (decreasing valve overlap) you will gain peak tq and high rpm tq. Plus it will idle MUCH SMOOTHER.

Natural Aspirations

I agree. In my situation I am compressor limited (JRSC don't hate it's for auto-x) and I feel that there is little information out there regarding this subject. I know what vtec combinations have been used with the greater success, but challenging why is what keeps my mind calm.

I suppose that if you start with too large of a cam, dialing out the overlap by opening the LSA at some point your going to run into some issues with lower exhaust gas velocity and intake reversion. I'm not so sure that the exhaust gas velocity is as important in a supercharged setup as a turbo as long as you have a free flowing exhaust, but the intake contamination would be major negative.

IMO in any boosted setup you should be able to open the intake a little sooner and keep it open a little later due to the manifold pressure being higher than that of a naturally aspirated counterpart, along with closing it soon enough to take advantage of any additional VE from port velocity.

As long as overlap is helping introduce fresh charge into the chamber and not over filling the cylinder and pushing out the exhaust it is welcome.

Just a few things I've been thinking about, seems that none of my locals are quite as in depth about their thinking and I have to get on here and express my mind.

DDTECH

Generally, nitrous / supercharge cams tend to like the same.. a good even amount of duration and a good amount of lift.
Where as most have seen good success with alot of lift, and alittle duration being turboed.

Its really kindof hard to believe with all the people that go turbo, there is not more turbo cams out there.. more or less cams like the s2s2's/bloxb's, pro1's or itr cams are majority of whats used on turboed setups..

Going any bigger, creates problems with airflow because of the duration and LSA coming into play on the setups.. you dont want too much duration because then you're just shooting air outta the exhaust and not ultilizing the turbo's air.

you want some overlap but not alot, it has to do with bleeding off the compressed air which defents the whole turbo purpose..

i think you and I are going to get together and we'll test out some theory's soon NA.. i'd like to market some SC cams and we'll see how they perform.

00Red_SiR

I think what you're doing with the JRSC is cool, in fact I like reading about a lot of the things you do because they're a little different than the norm and that's a great way to learn (something you demonstrate often). I and many others learn from that kind of thinking/doing as well. I've recently grown interest in the boosted cars, probably because I think I'm "all motor'd out" lol. I would love to spend some time testing some of the things you were mentioning and seeing how they react. If only time and money grew on trees eh?

Natural Aspirations

Thank You sir, that compliment means a lot coming from you.

I am interested in working with anyone whose agenda is to help the good of the community. Working in steps and making things easy to replicate and understand would be my overall goal, I have been browsing other boards and that seems to be missing here anymore. I have a few ideas that could make intercooling a bit cheaper and able to be done DIY or at a machine shop without welding.

Money tree, hmm..

N/A shoot me an email and we can discuss cams.

DDTECH

LOL, when you say N/A i assume you mean me right? I should get my phone back next week sometime, that away, we can txt, instead of silly emailling lol

Natural Aspirations

Whoops yeah