I want valves. Tell me whats good and what's not.

[oldcorollas]

I plan on an SC14 pushing 15 pound to start with, and keeping the stock redline.
- HKS Cam gears
- HKS springs
- JUN titanium valve spring retainers
- Shimless buckets from the 1SZ-FE
- Combustion chamber modified to TRD Group-A specifications.
- Intake and exhaust ports smoothed etc.
- Combustion chamber and valves ceramic coated
- Decent valves, probably Ferrera Stainless valves. <- Not needed?
- Custom built Tighe cams. Around about 264 duration, 8mm lift.
- 5 angle valve job.
- New valve stem seals etc.

to be honest, that sounds like a very mild build.. basically just a reco'd stocker

the cam gears are onyl needed if you want to move cams around.
the springs will make no difference with low lift and stock redline.. may as well stay stock.
Ti valve retainers.. very little point for stock redline and stock weight valves.
cam lift is not high enough to warrant shimless buckets.
all the rest sound slike a basic cleanup and reco.

8mm lift cams? why custom tighe? are you going to ask them for particularly fast ramp rates or something?
HKS already do 256/264 8.1 and 8.35 lift cams.. toda do a 7.9

you need to work out what you want from the engine..
ie, revs, or torque, or maximise efficiency, or all three..
ie.. light valves and valve train AND light rods/pistons to reduce losses and reduce stresses at high rpm..
large lift cam, to maximise breathing potential from SC at high boost (15 is not high), or to maximise breathing efficiency of the SC (in which case springs and shimless will be needed)

you can7t go hugely larger with the valves anyway, but you could go lighter.. are the stems already abotu 6mm? maybe can't save any weight there.


if you are sticking with the small cams as a test of duration, and will go 10 or 11mm later, then you may as well get the springs and buckets etc now (unless you go to larger buckets?
but seriosuly, before spening more on valves, actually measure the flow of the head with stock and oversize valve (will you go bigger seats also? is that possible?) and see if there is any benefit. perhaps at low lift, but.. better having higher ramp rate and larger lift, while minimising overlap to suit your rpm limit for the SC...

etc...

[TERRA Operative]

15 is to start, until I can afford a screw type charger that'll push more along the lines of 25 pound plus. (Depending on street driveability...)

8mm was just a number I thought was a good start to begin playing with. A few mates got cams made by Tighe (fast ramp rates and all) and they turned out great. I know that worked, so I was going with that.

I'm getting the head flow tested etc, maybe I should start at something like 10mm lift or so? I would like pretty fast ramp rates with decent lift (I will be going for aftermarket ECU, probably Microtech if that changes anything).

Not sure on valve dimensions, my head is off getting crack tested etc, so I can't measure anything...

Basically I want to build the head (and then the rest of the engine) to handle whatever I throw at it in regards to cams and boost. It's probably going to see hill climbs and the like primarily, so I'm assuming torque and decent power from midrange to redline is the flavour of the day?

[takai]

Above 9.5mm ish lift the 4AG ceases to be a non-interference engine, at this point you may as well go OTT.

That said, for a SC engine, the ratio of power gained to dollars spent for head work and trick bits is VERY high. The ratio of power gained for dollars spent for extra pounds of boost is much lower.
It has been shown many times that the stock GZE engine can handle 20+psi, and even up to 30psi when cleaned up and tuned suitably.

For hillclimbs and general low speed events (2NS) you arnt going to see redline past second gear anyway, and with the SC and FWD youll have issues keeping traction anyway. Remember the GZE in stock guise with a 175mm pulley makes 9psi by 1500rpm and 15psi at 3000rpm. Traction is the biggest problem here.

[oldeskewltoy]

Hmmmmmmmmmm my ONLY concern with stock springs is rpm capability..... If he is running a 264 type cam, peak power will be made at or above 8000 rpm (properly tuned...) Will the stock springs hold up to sustained 8k rpm?????


This is the ONLY reason I went with the TRD 90501-AE851 springs....

[takai]

Yes, they will hold up to it fine. The stock redline on the smallport is 8000rpm, and when i had the stock smallport engine in the spoonter it ran 8500rpm day in and day out.

[TERRA Operative]

This is the ONLY reason I went with the TRD 90501-AE851 springs....

Don't the TRD springs require TRD spring seats? I remember reading that somewhere.

[TooF]

i dont think so. i think its only if you use the TRD retainers you need to use the matching trd under bucket shims.

[oldeskewltoy]

Yes, they will hold up to it fine. The stock redline on the smallport is 8000rpm, and when i had the stock smallport engine in the spoonter it ran 8500rpm day in and day out.

Well The TRD spring only cost me $160(w shipping) and they are all new.... btw... they fit the stock seat and retainers.... the AE901 springs are the ones requiring all the special bits.

[TERRA Operative]

I think TooF has it right. I remember something like that, couldn't remember what parts they were exactly.

[nick.parker]

How do you want the car to drive?

I ran stock cams (and custom ECU) with 18psi from an SC14, and the low end torque was psychotic, sending the nose of stock sprung AW11 comically skywards when nailing the throttle off idle! Particularly the low end torque was fantastic, but the car felt comparatively asthmatic above 5500rpms....

I got greedy, I went to Wade 267, 7.9mm(at valve) life cams. Low end was shite, mid range was really good but not feeling into full stride until 3K rpm, top end still not that great. Drove like this for 4 months or so.

Went back to shorter duration cams. Car was instantly SOOO much more fun to punt around due to the engines low rev responsiveness.

I would say keep the cams small. If money was no object I would do anything to make the breathing better than didnt involve long cam duration.

Ultimately the SC14's low efficiency at high boost/rotation speeds is the limiting factor for high engine rpm performance. THIS IS NOT TO SAY YOU CANT HAVE FUN WITH IT - I ove it!

this is 17psi with 256in 267exh cams. with very conservative initial tune to get it running
http://www.youtube.com/watch?v=vIOTXlENNbM

Cheers, Nick.

[fixeruperer]

i miss that sound

[TERRA Operative]

The intake will be getting a full rework, the pipe from the SC to the intercooler and the intake manifold will be 'fixed' to provide maximum flow. An air to water intercooler is on the cards too.

Basically I want something with torque and a good top end. I know it's a trade off, but mid to high end is the priority (high end being up to 8000).

Basically my idea is to make things flow as easily and spin as easily, so I can forget about them, then play with boost and cams.

[takai]

And you are shooting yourself in the foot. For hillclimbs you want throttle response without overspinning the SC.

[TERRA Operative]

But I'm not going crazy with the supercharger?? The underdrive pulleys, lightweight internals and free flowing intake/exhaust will help throttle response won't they?

If I spin the charger at 1.3 times engine speed, I'll get full boost (18 PSI or so, 10000RPM rotor speed) at about 7700RPM. I can live with that.

Until I can afford a screw type charger...


nick, what lift were you running? what do you think 265 duration with around 10mm lift would be like?


Hmm, by my rough calculations, for an SC14, I'll need a rotor speed of 8660RPM to make 15 PSI boost at 7500RPM engine speed.
That equates to a pulley ratio of 0.866. What's the stock 4AGZE crank pulley size?