Rb25det Cam's And Red Line

[Rezlo]

RB25DET S1 with a GT35R

With N1 oil pump, eagle rods and CP pistons whats a fairly safe rev limit on the stock head?

Also if I run the Tomei poncam's with that turbo, what are my realistic gains? who would it effect my red line on the stock valve springs? or is it worth at that stage going with a slightly stiffer set?

I need to get about 8500rpm out of the engine in 2nd and 3rd to make best use of the local track,

Thanks

[R31Nismoid]

8500 is too much for a stock head.

You'll be getting valve float etc.

I ran 8000rpm as limit in my stock head and it was ok. But some people have had issues even with that.

So going another 500 isnt going to see things last too long i would imagine

[GTS-t VSPEC]

I ran mine at 8200rpm with standard head, and now 8500 with cams, valve springs and new guides etc.

[Rezlo]

My whole motor has 15 000km's on it, so hopefully my guides ectr are still mint, with a set of poncams and springs fitted, at what sort of RPM can I expect the lifters to let me down?

It will only be needing to go over 8000rpm for maybe 1 or 2 seconds at a time, not very often at that.

[GTS-t VSPEC]

I still have the standard lifters, and at 8500rpm they haven't let me down so far.

[Rezlo]

What cams and springs are you using? also what turbo?

Im just running out of gear coming into 2 corners at my local track, and a few hundred extra RPM would go a long way, currently a stock RB25 s1 with a GT3076R and loads of supporting mods running 1.4bar, going to be building the motor at the end of the year so trying to get all the parts planned out and on my shelf by then.

[R31Nismoid]

If you intend to build a motor that lives at the track

You would be mad not to spend money on making the RB25 head reliable.

For street/drag in bursts its ok.

Extended RPM you'll have issues

[N I B]

This things been turning to 8500rpm + for years on stock 25 head with Poncams making silly power and running 62.5 laps at wanneroo long track on Toyo 888 radials.Has won State championships. The RB25s only ever hurt one bearing in all those years.

[Rezlo]

My car is not a track car, its an everyday car which i use maybe once a month at the local drag strip or race track,

Currently making 352kw at 1.3bar with:

Stock internaled RB

Greddy intake mani

76mm charge pipes

GT3076R

Tial 38mm gate

PFC

740cc

Meth injection

and the other usual things like pump, ectr,

To be done end of year:

8.5-1 forgies

eagle rods

ARP head studs

ACL race bearings and gaskets

tomei oil restrictor

external oil return

N1 pumps

pump collar

ectr,

Only thing I havent worked out is a good street reliable head combo, I definatly want to go with the poncams for a nice easy to drive setup, but not sure what other tried and tested parts you guys use with the hydro lifters.

[MBS206]

Why not change the diff ratio?

Whilst you won't be accelerating AS quick, you won't be running out of puff either.

On the standard cam, I personally don't find all that much power above 6500 compared to if I upshift at 6500RPM.

You need to remember, when you put your power through the different gear ratios, you get a set amount of torque at the rear wheels, and alot of the time (Nearly all the time in stock cams) it's more beneficial to shift a few hundred RPM before the standard redline to get maximum acceleration...

[Cubes]

Thats some healthy power out of the GT3076r.

I assume that's with the .82 rear?

[The Mafia]

sounds a bit high to me, especially at the boost level

[Cubes]

hrmm yes and no.

If its the .82 then I think it could be about right but on only 19psi?? Maybe 22psi

You picked up around 30rwkw from water/meth. With the .8 rear and ~1.5bar on pump they make 320rwkw ish. So 320 +30 = 350.

[R31Nismoid]

I suspect a hub dyno

[Rezlo]

Wheel dyno,

It is a .82 with the 4bolt GT outlet, I run quite a bit of timing to, meth works quite well for that,

http://www.rezlo.com/Pages/silvia.htm that was it a few months ago before the new intake and charge pipes, last video clip is of the current setup, Just had a drag event on sunday, trapping at 209kph at a rather slow 12flat due to some traction issues im working on,

Edited September 4, 2007 by Rezlo

[Cubes]

129.8mph.. I'd say the power is definitely up there. No doubts here.

I also run a Gt3076 .8; looking at water meth in the near future.

Top work.

[Rezlo]

129.8mph.. I'd say the power is definitely up there. No doubts here.

I also run a Gt3076 .8; looking at water meth in the near future.

Top work.

Thanks, I try to keep it looking as clean as I can.

GT3076R seems to work well with the RB25, but the meth inj made one of the best improvments to my car, I use a devils own progressive kit with #15 nozzel running a 50/50mix, Ive been up to 1.5bar on the streets with 95pump fuel with zero detonation, though only for short bursts as I want to keep the motor together till its time for the build.

Any Idea what the poncams will do spool up and top end wise with my setup? Ill probably go with the tomei springs at the same time, just worried about the added spring presure on the hydro lifters at higher RPM.

Anything else anyone can coment on internal wise ontop of my list above?

Edited September 5, 2007 by Rezlo

[Cubes]

The cams will help hold top end up for longer and improve spool slightly; as you have a short runner plenum this with the cams will allow power to peak a little later as result making a little more peak and possibly improving that TS down the 1/4.

Go the springs and cams. The springs won't cause issues with the hyd. lifters.

A set-up that has the potential to do very well.

With your build up consider a series2 crank or a jun style crank collar so you don't go breaking oil pumps.

Head oil restrictors - 1.5mm up front, blocked off rear as per sydneykids recommendation works VERY well.

How hard do you currently rev it? Where does power peak?

[Rezlo]

Ive got a jun pump drive ready for install, I also have a tomei oil restrictor ready for the rebuild,

Ive currently got my shift light coming on at 7k, shifting at 7200 to 7500 some times 7700 if i dont catch it in time, set the redline up to 8200 so I dont touch it (not a fan of fuel cut at full boost)

At the moment it pulls pretty linear from 6000 up to 7500, I dont feel much drop off at all, If I shift under 6500 it knocks the wind out of it, usualy pretty badly.

My peeve with the setup is that its a touch violent coming into boost, I want to smooth it out especialy in 1st and 2nd to help with traction, and being able to run it up to 8000rpm in 1st and 2nd would help quite a bit, as our tracks arnt that great and you have to work at keeping it tractible even with 275 wide M/T's.