Oversized valves?

[84suprade]

im a bit off but how can you tune any thing with that air box or trap door
i have done alot of tuning on cars but i relly dont know what im playing with here and i would not add more fule unls you add the that turbo kit thay have

[moonpie33]

Umm search...... its easy to trick computer's and its safer to run rich then it is to run lean. if you have what i have said bigger valves and cams and a wideband and a computer that lets you adjust your air/fuel then you can achieve maximum power that those mods have to offer

This is what i have heard!!!
running rich loses power coats cylinder wall and can lead to ring failure over a long period of time. (carbon buildup)
running lean gains power but can lead to detonation. (am i forgetting anything else here?)

So you make the pick then there is always the in between.

[toyotaman5mge]

wow this is alot to take in.. I think that the osv is a good thing, but you have to do all the other thing that golong with it.. like intake, exh, so forth.. from what I have found is that the stock setup is good. but bigger valves, you word have to make the runners bigger to. I'm making my own intake right now. and I'm useing 33mm pipe for the runners. and a 85mm tb. I have 2.5 mm osv. and 225cc with a safc. and 2.5" exh, no cat. I'm going for 260 rwhp, with a 6mge.. and cams. exe, exe. you can't do one with out the other.. it's just a wast of money..so that is just my 2 cents..

but good luck with all the infore. use it with care.. found out as much as you can, and then do what you feel is better,

[ABUSEDDOG]

Oversize valves allow for a bigger intake charge at a lower point of lift on the cam profile, if the motor has no need for a bigger intake charge...OSV are really not needed.

[moonpie33]

yes but you will have a better flowing head!!! and like it was mentiond you will still fill the power difference you just wont achieve alll the power there is to offer without all the mods! now you can only port a head sooo much until you have a head that does not flow properly.
and toy go with a 3in and headers

[toyotaman5mge]

ok now for the point.. just osv alone will not up hp.. there are other things that need to be done to get there.. like what we have all tuched on.. we can set here and go back and forth all day long.

[ma67 lover]

yeah im planning to do like all this. caming porting ect. i have headers and exhaust all 2.5 inch. im just wondering what you all like for brands of wide band o2's

[moonpie33]

Thats where you are wrong toyotaman!!!! osv do up hp and yes you can feel the difference. I dont have my dyno charts but with this mod I felt a huge difference overall and better reaction time. And this was before i got my cam in.
Osv valves alow a head to breath better etc etc..... think of it as headers in the head also it does give you a hp gain! Anyone have a dyno chart before osv and then with osv?

[toyotaman5mge]

yes moon your right that you will see a hp gain. but to get the full gain, intake exe exe. you might see like a 4-7 hp gain, which can be felt in the car. but to spend that much for osv and not to get the most out of it is just not right. I have been working in the car feild for over 17 years, have worked in a import shop for about 10 of that. if you are going to take the head off to do osv and that is all, you can port and under cut and see a big jump in hp. then put exh cold air, cams, exe. I think that we are all saying the same thing here. lol I have had my mkII for about 14years now, i have a 6mge with little mods here and there. I have put down 159 rwhp and 181 flb. thats na. yea don't sound like much, but with 4:30 in the rear end, and w58, wow it's fun.. i'm building a 6mge with high comp, and making my own intake, header, fuel system, with the 2.5 osv and exe.. I hope to hit the 300 rwhp.. doing a stand alone to, with my own maps.. has any one hit the 300 mark here yet? I will be done in summer 2009..

[StanS]

My comments about osv/afm/210 injectors referred to an 84 engine (since that's what I have) where the ecu only gets idle/wot/everywhere else info from the tps. 85 tps/ecu is different.

extra air without extra fuel can lead to burnt exhaust valves (without detonation) since explosion runs hotter. You also need a EGT monitor when you get enough hp.

larger diameter runners may lead to less flow (hp) than stock runners. Use search for the reason if you're interested. It's in one of my posts. iirc, Sarinas Dragon has calculated that the stock max VE of the 5mge is from 1.05 to 1.10. That's very hard to beat.