RB26 Valve Train - Need Advice

[evilgtr]

I dynoed at 470whp at 18psi with a real dirlty tune (stck ecu reflash) I will have a Vipec to clean it up and also be running meth so 550whp is well within reach on N1's (similar to the -7's). SHould be able to run 22 - 25 psi with the meth on the retune. If I ever get my head sorted out..

Mitch32 Thanks for the input, Lightspeed is a certified Ferrea dealer so i was considering trying out heir valves. Right now the only mods I have to my head are after market cams (260 deg, 9.15 lift) and a 5 angle valve grind. What do you think I sdhould upgrade to for my head ? As mentioned above I will be shooting for around 510 - 550whp with the meth(wherever it ends up,not going to run it on the limit) I dont think I will need to rev over 7500rpm but maybe 8k max. The rest of my engine has been built to support this.

Please let me know the set up you would run and how you would set it up,thanks again guys this has been very usefull my car is going in a week so I need to get a game plan together)

[Skym]

From what I could understand from what a cam manufacturer was saying, don't want valve springs too hard or too soft, but I gather it depends on cam used -

http://www.kelford.co.nz/faq

With what you are saying about valves snapping, there must more too what happened, as there are GTR's running around with stock valves, 700hp at engine (542rwhp+) and are reving to 8000rpm without problems (using Tomei, Naprec valve guides). Unless you were bouncing off rev limiter, or the valve guides you were using were not suited to stock valves???

I think stock exhaust valves are hollow / sodium filled, so they can take the heat away from the face of valve. But yeah, aftermarket exhaust valves are stronger due to not being hollow + sodium filled, but usually not done unless your porting head, fitting bigger cams, etc to take advantage of the extra 1mm size and looking for 700hp+.

I know Heat Treatments run HKS valve springs, etc in their R32GTR RB26 (RB28) drag engine and they are now producing 1600awhp+ at the wheels. Says alot about HKS head components.

This is when they were producing 1400awhp??? and mentions the specs of engine -

http://www.youtube.com/watch?v=rI8TaplX5iA

Heat Treatments do make their own cam buckets, etc -

http://www.youtube.com/watch?v=f8rIHcnTfkU

I run the same brand oil in my cars engine.

[mitch32]

I'm not saying HKS is bad or any of the other Japanese aftermarket companies are bad its just they tend to charge a lot more then USA based companies do. The USA based companies produce good products. Also a lot of companies share manufacturing, for example Daikin Clutch makes almost everyones clutches, CP pistons are the same as HKS (so I'm told), Tomei Rods are the same as Eagle rods, etc..... If I can get it in the USA or Canada I'll go that route before I go with something foreign, its not only the cost but availability and customer service (its easier to deal with a company in North America then it is overseas).

Ferrea Valves are probably the best valves you can buy in North America (maybe even in the world), they will cost you maximum 900$ for all 24 and IMO thats cheap insurance. You can get supertech guides for around 80$ for the exhaust side. Supertech also makes springs and retainers for around 400-500$. There is also Brian Crower springs and retainers, a lot of sr20det people run Brian Crower stuff.

With N1 turbos I've never seen numbers over 450whp, I have no clue how the hell you got to 470whp but I'm guessing your on a dynojet. Or maybe your tuner just can break records easily. If you make over 500whp on the N1s then you probably have the highest horsepower N1 rb26 in the world.

[evilgtr]

Wow you had to beak the N1 turbos and the tuner hey,Just when we were starting to believe you knew what you were talking about... You can call Andrew and Jurie from Ztune they tuned my car, made 472whp on a mustang dyno at Racing Greed also known as the heart breaker for the low reading it produces. Amazing how a person can lose credibility so fast.

Anyways.. thanks for the input on the valves and different head components I will be speaking with Cam to see which direction to go with all this new found info. Most likely will be ferrea valves and we will see about the rest of it. Time will tell ,I will update this thread when Im finished to hopefully help other people with their valve train questions.

[mitch32]

My credibility has gone down, lol.

I'm just saying from what I've seen on all forums I've never seen more then 450whp on N1 turbos. I spoke to Mike M. from Ztune a lot over the past few months and he even told me that with the gt2860-5 you can't get over 515whp and thats with a full ported head, water/meth, and big cams. The gt2860-7 have even less top end power, if you don't believe me go on Garrett's website. I honestly just find it hard to believe you did even 470whp on a dirty tune, if anything its a crazy good tune and thats probably your limit. The dyno also might need to be calibrated. The guys at Ztune know what they are doing so maybe they can break records that easily. Or maybe theres something your not telling us, like that your using some racing fuel. Look I'm not bashing you I'm just writing the numbers I've seen. IMO the N1 turbos are actually one of the better turbos since you get a responsive car and have some high HP.

[Skym]

With later model R34 GTR N1 turbo's, can extract more hp. 415awhp seems to be common with those turbo's at a midlish boost level (sub 20psi??) with cams, stock valves, etc on R34GTR Nur (Mines spec engine). R33 N1 turbo's produce slightly less hp.

The 2860-5 are good for around 542awhp with R34GTR on Hub Dyno with 98 octane pump gas. Hub Dyno's read lower than a Dynojet when compared.

Can back that up with a dynochart -

http://2.bp.blogspot.com/_vhpEGyEVhes/SNcpZUXHl9I/AAAAAAAAA_A/1SD8hIXQv2w/s1600-h/ST+R34+power+1.jpg

404.7awkw x 1.341 = 542.7027awhp.

Boost graph -

http://1.bp.blogspot.com/_vhpEGyEVhes/SNcCmsctQdI/AAAAAAAAA-w/B82_PbEDkhc/s1600-h/ST+R34+boost.jpg

Can see the boost drop off at higher rpm's (running out of puff). It could be due to small A/R exhaust housings. Supposedly if ran higher octane gas (only running 98 octane pump gas), can extract more hp (I gather due to running more ignition timing with higher octane gas). Note engine is being reved slightly above 8000rpm.

Thats with Tomei Poncams Type B, Tomei valve guides, Tomei valve springs, stock valves, MAP sensor, HKS Fcon ECU, stock conrods, forged pistons, etc.

Just to back that up, it seems to be average awhp for 2860-5 turbo's on RB26 in a R34GTR -

http://2.bp.blogspot.com/_vhpEGyEVhes/SdQm8r2dkYI/AAAAAAAABrw/tFQwsiO094s/s1600-h/BlsckR34+power.jpg

403.7awkw x 1.341 = 541.3617awhp

Boost graph -

http://3.bp.blogspot.com/_vhpEGyEVhes/SdQm8rYebKI/AAAAAAAABro/etxxnz0nV3A/s1600-h/BlsckR34+boost.jpg

But that's with stock bottomend, Tomei cams, etc and Z32 AFM x 2, PowerFC. 1.2 bar used for street use. Note that engine is being reved to around 7800rpm (stock bottomend). Might be bigger A/R exhaust housings on those turbo's or the fact that it wasn't running same boost level, as boost is not dropping off.

[cortexx]

Back to the original subject - you could consider using cosworth valvetrain parts , cosworth parts are incredibly high quality although a little on the expensive side . Popular in Europe .

Im in the process of building a head - im using tomei poncam b's with adjustable wheels , HKS step 2 valve springs , Brian crower titanium retainers with supertech nitride coated valves , tomei cam cap studs and Jun valve guides . Head will be port matched with ITB's and exhaust manifolds .

I'll do a write up on it with pics when i get the chance - ill add it to my build thread .

[gtrjon]

this thread is 2 years old

[evilgtr]

Yes it is not sure if I updated but decided on the Tomei components when repairing my bent valve. All good so far

[cortexx]

Oldies but goodies , not sure how it came to the top of the pile if it was 2 years old , i dont go delving usually.