sabastian458

iTrader: (25)

Has anyone done flow testings on the head in these situations?

Full stock head, Stock head with +1 mm valves, mild port with stock valves, mild port with +1 mm valves, extensive port with +1 mm valves?

Post findings of any of these combinations please. (I see the one set of #'s from buschur's test of mild port stock valve, to extensive port with +1 mm valves)

Jackson Machine

iTrader: (9)

Every valve is a little bit different.

icantdrive75

iTrader: (8)

I actually do have a set of 1mm over. I can do the valve seat and lap them in, perhaps the guys at JAM who've been kind enough to give their input will give me a hint at what angle seat to cut. I would imagine it depends on the RPM range of the motor.

I don't have any practice yet, but I could have one of the good guys here look at the port and see what they thought about grinding on it. Most will undoubtedly be scared to touch it.

icantdrive75

iTrader: (8)

No I wasn't. I'm not saying that the entire 23% - 10% gain was attributable to the valves, but David Buschur seemed fit to mention that the head really took off with the valves in it. Either he wants to sell valves, or that's what he felt was the main contributor to the numbers increase. Do you know how much "additional" porting he did? Maybe he just cartrige rolled it but felt it would be wrong to post the new numbers without mentioning he'd done additional work. We're mincing words here. There's no real resolve to this argument without david buschur explaining exactly how the test went that fateful day 5 years ago.

Aby@MIL.SPEC

iTrader: (161)

1 valve profile, back-cut, seat in the head profile doesnt work in all cylinder heads. this is due the port angle, valve angle, shortside radius, along withan other handful of reasons.

i planned to answer the OP questions, buti dont have the time at this moment.

i plan on doing my own head with +1mm int & oem sized exh valves. the valve size ratio isnt right from the factory, relative to bore size IMO.

other things limit the amount of valve size 1 can increase, shrouding by the cylinder, valve spacing between intake valves, location within the cylinder head etc.

there is a lot of work that goes into a good cylinder head. absolute flow is not what its about, there is tumble & swirl to that need to be considered.
i have seen heads that flow more than others, but lack in tumble, make less power throughout the rev range.

sabastian458

iTrader: (25)

would it be worth experimenting with mixing up the oversizes on the intake and exhaust? Like for 1 of the intake valves run a +1mm and the other (in the same cylinder) run +2mm, which would cause the intake charge to flow into the bore more on 1 side causing it to "swirl" so to say? Or am I just being stupid

Erik@MIL.SPEC

iTrader: (94)

Aby isn't the first person I've heard suggest that there's power to be made with non-matching valve sizes on the Evo head specifically.

And that boy knows cylinder heads.

sabastian458

iTrader: (25)

For the person who asked how much lift I was looking to run here is an answer;

my current cams- BC STG 3 280's
Adv. Dur.- 280/280 Dur @ .050- 218/216 Lift- 10.80/10.36mm

1st canidate- BC STG 4 288's
Adv. Dur.- 288/288 Dur @ .050- 222/220 Lift- 11.88/12.14mm

2nd canidate- GSC S2's
Adv. Dur.- ???????? Dur @ ????- 274/272 Lift- 11.2/11.5 mm


GSC doesn't give alot of specs on their cams so I doubt if the S2's are what I will go will. The BC's exhaust cam has a TON of lift, which I havent see other cam manufactures do (make the exhaust cam have more lift than the intake cam)

Aby@MIL.SPEC

iTrader: (161)

potential for more flow if the environment allows for a larger valve. larger curtain area.
? every application is different & cant be summed up in 1 thread..

inconel will live longer in the same enviro than nitrided
nitriding is a hardening process. a nitrided valve will live longer in the same enviro as s.s.

oem guides are casted crap. they are notorious for cracking in road racing environments....however, if you never check, you'll never know

stay hydraulic, unless your willing to yank your cams to change lash caps that you dont have a variety of differnt sizes of or have the ability to surface grind on a machine that you dont own or have access too.
yes. the purpose of the spring seat is to keep the the springs where they need to be & not getting stuck in the others coils.

it's called PTV...piston to valve clearance....knowone can know for certain what your engine wil be doing, even if you told them all the product specs that you have purchased.

when a true race engine is built, in all actuallity, it has been assembled/disassembled ~2 or 3 times, just to verify, it has been machined accordingly & to re-check that everything is where it needs to be...and if it's not, the parts go & get machined again & rechecked, then final cleaned then assembled.

people wonder why properly built engines cost so much. it's due to the time spent verifying that everything is as expected & will live in perfect harmony @ max revs for your engine set-up.

At the end of the day, people wonder why joe-blow has a factory freak, because his assortment of parts stack in the favor of making power. all while donny ******** gets stuck with a poor mismatched, detonating engine that doesnt make squat for power.

sabastian458

iTrader: (25)

ok, so I am narrowing down my setup. so far I have; Definatly larger valves (stagard combo posible), Iconel exhaust valves, Nitrided intake valves. Stock lash adjusters.

new questions are:
Where can I get better valve guides and seats?
Are Brian Crower single coil springs W/ titanium retainers sufficent for a stroker reving no higher than 8000-8500 rpms?

icantdrive75

iTrader: (8)

I'd stay away from installing new seats. I've heard they're a proverbial ***** on an EVO head, even to the point that if the seats are gone the head is gone. I got valve guides from FFWD connection. Pretty sure they're supertechs. Pick your favorite shop and I'm sure they can order you some.

The valve on a stroker isn't moving any faster than the valve on a 2.0, so if a spring works for one it'll work on the other. I'm sure 8500 won't be a problem for them.

And as for the staggered valve thing, there's no reason to reinvent the wheel. Leave it to people with money and time.

Erik@MIL.SPEC

iTrader: (94)

I wouldn't say it's for the people with money and time (I'm assuming you're talking about R&D, etc.).

People like Aby can look at a head, take measurements, and know what to do from there. Then again, Aby has been building race engines for 20 years so it may be easier for him than others

sabastian458

iTrader: (25)

well I may just go with +1 mm on both intake and exhaust with a mild porting, new seats and guides. I know I will have to have the combustion chamber reworked to remove the imperfections caused by the broken ring land.

Is it worth it to replace the head gasket with an aftermarket one, or is the stocker good? (I am still running a stock gasket)

icantdrive75

iTrader: (8)

Sorry I should have said money, time, or a massive wealth of knowledge.

icantdrive75

iTrader: (8)

Depends on how good you are at changing head gaskets. If you go to a metal gasket I hear you need to put a very fine surface on the head and deck, so that may not make it worth it to you, but I've only heard that from people on this website, not from people I trust.