Imput on building head!

[Super_Dude]

You say you don't want to rev to 11k but your running very high duration cams and dual valve springs? That doesn't make sense. With that turbo I would run 270/270 10.8 lift max. I ran these on my car with a GT4088r (similair size to yours) and low end power was frustrating at times. I can imagine 280's would be even worse.


for valve springs I would check out Cosworth. The supertechs are way to stiff and most of the japanese stuff is either barely stiffer than stock or way to stiff. Cosworth is the perfect in-between.

Also, I've never seen anyone publish results directly comparing OS valves to factory sized ones. I have heard there are little gains in the under 1000whp world and it doesn't even make a huge differnce above that.

Dsports R33 ran over 1000whp with stock valves. It ran for years with huge power but eventually destoryed an exhaust valve.

[gtrjon]

let me clear up a few things. when i said i dont want to rev to 11k i was being realistic but at the same time the cam and spring set up are in place to where i can rev my motor to where its going to make power. theres no point in reving to 11k when i stop making power at 9500. and yes 280s will be a big laggy in the low end but this cam selection was made at the recomendation of a few experienced mechanics. they are going to make crazy power in the top end. i have also ran supertech valve train before and i love it its some of the best bang for the buck. as for getting aftermarket valves they are not for added power i dont think anyone gets aftermarket valves and expects huge power gains. but rather its a simple mod that is realitvely cheap that will provide me piece of mind. several people have told me the stock valves are strong and will work but then with 15k that i have in my motor floating a valve and kissing my piston is really the last thing i want. its for reliability not power.

[derk]

let me clear up a few things. when i said i dont want to rev to 11k i was being realistic but at the same time the cam and spring set up are in place to where i can rev my motor to where its going to make power. theres no point in reving to 11k when i stop making power at 9500. and yes 280s will be a big laggy in the low end but this cam selection was made at the recomendation of a few experienced mechanics. they are going to make crazy power in the top end. i have also ran supertech valve train before and i love it its some of the best bang for the buck. as for getting aftermarket valves they are not for added power i dont think anyone gets aftermarket valves and expects huge power gains. but rather its a simple mod that is realitvely cheap that will provide me piece of mind. several people have told me the stock valves are strong and will work but then with 15k that i have in my motor floating a valve and kissing my piston is really the last thing i want. its for reliability not power.

i think you are confused on which parts do what... aftermarket valves will not reduce the chance of valve float or add reliability to the engine in anyway, aftermarket valve springs are what will reduce valve float.

oversized valves should be used in conjunction with a port/polish job that was geared towards the oversized valves, so yes.. people do get oversized valves for more flow, which in theory = more power, no one gets oversized valves for reliability...

[gtrjon]

i didnt say neessarly oversized valves i said "aftermarket" valves. which can be standard sizing. im not confused as to what does what. oem valves are weaker then aftermarket yes oem is strong but aftermarket is still stronger the chances of bending an oem valve vs an aftermarket one gives me the piece of mind. i dont want to have stock valves and bend one a month after my motor is back in. this happend to a guy on here i forget who but ill try and find it. my valves are 20 years old and they gotta be getting weak. yes i could go new oem but whats the point when aftermarket valves are only 500 bucks.

[Super_Dude]

You should do more homework on the extra stess the double valvle spings put on your cams. It's better to have them to stiff than to soft but double valve springs are for 11.5+mm of lift and 12k rpm. stockers are good for 9.1mm lift and 8-9k rpm. For best reliablity something in the middle is best.

[caliber676]

derk we need more info!!! caliber we should meet up some time. i do all my car stuff at my buddies shop in new west. evolution automotive thats where my car is in hiding lol you should swing buy some time!

Sounds good man, I'll try to find some time in the coming weeks to come out. Just going through the last term at BCIT for mechanics so work load is a bit hectic.

[gtrjon]

Sounds good man, I'll try to find some time in the coming weeks to come out. Just going through the last term at BCIT for mechanics so work load is a bit hectic.

yea man for sure i just finished my year at wwu business mgmt.!

anyway how do you guys feel about tomei solid lifters? i know rb26s have solid lifters stock but what are the advantages of going to tomei? i dont see many people doing it

[MarusGTR]

yea man for sure i just finished my year at wwu business mgmt.!

anyway how do you guys feel about tomei solid lifters? i know rb26s have solid lifters stock but what are the advantages of going to tomei? i dont see many people doing it

Arent stock hydraulic? Btw, they're right about too much spring rate, you could actually induce vibration with too much energy contained in the system. You could get an engineer to find the optimal spring rate for your cam duration and profile. I've done it a few years ago in a course, it wasn't too hard IIRC.

As for ppl saying new valves wont stop float, are the stock valves sodium filled? I'd see less weight from a forged and CNCed valve than a stocker, less weight, less spring rate required.

[GTR-Dad]

Stock is solid - shim under bucket.

The guy who floated a valve shortly after tuning decided he should have replaced his OEM springs with something matched to his application.

+1 for considering the focus and purpose of the parts you're fitting together. The last thing you want is to be rebuilding the top end early because of excessive wear resulting from super stiff springs that are not really required for the stated target application.

My engine is currently going back together with 1 mm oversized valves and no other airflow mods. I'm planning to tune both with and without water/meth injection so there should be a reasonably good valve size comparison available.

Dan

[Black BNR32]

The quench pads will make 91 octane fuel act like 94 octane when you start to play with ign. timing (it makes that much of a difference).



Jon.

Hey Jon, would you mind explaining why? I'm guessing because it helps move the mixture away from the edge of the chamber, further avoiding detonation?

[derk]

they are 1mm thicker to accommodate for the smaller base circle in the Pro-cams, you use them when you are using tomei pro-cams

yea man for sure i just finished my year at wwu business mgmt.!

anyway how do you guys feel about tomei solid lifters? i know rb26s have solid lifters stock but what are the advantages of going to tomei? i dont see many people doing it

[Super_Dude]

My engine is currently going back together with 1 mm oversized valves and no other airflow mods. I'm planning to tune both with and without water/meth injection so there should be a reasonably good valve size comparison available.

Dan

Awesome, That would really help clear this up. I've considered going this route down the road. When XS/cosworth built my head they recommend to leave the stock valves at my desired power level. I would be very interested the difference it makes on the dyno and driving around.

Your running jun cams right GTR-Dad? 9.7lift?

[Bruizer]

Hi Dan,
I'm curious to know why you pulled the head off a good setup that was running. Had some issues? I do recall reading (Xs engineering maybe) that the stock sized valves were best until 800whp or so. After that they actually caused gains in the right places. I'm most likely wrong there. Curious to know if I should have gone with +1mm myself if gains are substantial. having less power than you could be a reason I don't need them though.

Oh, what gearbox are you running again? Os 88 or something, 1-5? I'm expecting my gearbox to have issues with power soon.

[GTR-Dad]

Your running jun cams right GTR-Dad? 9.7lift?

Yes.

Hi Dan,
I'm curious to know why you pulled the head off a good setup that was running. Had some issues? I do recall reading (Xs engineering maybe) that the stock sized valves were best until 800whp or so. After that they actually caused gains in the right places. I'm most likely wrong there. Curious to know if I should have gone with +1mm myself if gains are substantial. having less power than you could be a reason I don't need them though.

Oh, what gearbox are you running again? Os 88 or something, 1-5? I'm expecting my gearbox to have issues with power soon.

There had been a bit of oil getting into the coolant since day 1 of the last build. It was time to drive when it first went together so I figured I'd run it for bit and see what happened. It didn't really get any worse, but I figured sooner or later the car was going to schedule a rebuild for me so I had it pulled apart. Cracked block away from the cylinder wall near the outside edge of the deck. ????

So, N1 block. Valves needed reshimming so thought I'd overhaul the head. Did zero homework on valve size benefits as it seemed obvious (at time, but I've been wrong before!) that less restriction would be better. I know higher flow velocity at low revs helps with torque, but wouldn't expect valves to be the governing factor there.

Anyhow, we'll see how it runs! I'll post dyno and driving impressions.

OS Giken close ratio 5 spd.

Dan

[gtrjon]

alright you guys lost me now. so if i want to run my 280 cams with the 10.8 lift what would you guys reccomend for valve train? single springs and titanium retainers? stock or aftermarket valves? stock or tomei lifters?