Camshafts, Bigger valves

datajon · **Posted:** Sat Dec 17, 2005 10:59 pm

Unfortunately, when it comes to camshafts, there are limiting factors, that require understanding, the time period for the valve to be open, for optimum power gets reduce, the higher rpm increases.

To get around this, the uses of high lift camshaft with longer duration are used.
Increase to valve’s allowing higher flow whilst open for the same time period.

Mass has lots to do to the way the engine will perform, the heavier the pistons, rods, crankshaft, camshaft, valves & train, flywheel etc, the more energy they soak up.

This is why the use of lightweight durable pistons, rods, valves, lighten & balance crankshaft, etc come into play.

For the optimum function of the up rated camshafts, vernier camshaft wheel are required, this allows for correct valve timing, for further improvements to power gains.

Its pays to, if building any sort of performance engine to follow these key factors, as money spent on the right combination of parts at the beginning will pay dividends later.

The cost of the camshafts for say .2mm extra lift extra would not give the same increase as a suitable valve size increase of 1mm.

This is how I quickly worked it out, I sized the valve into area and and multiplied by lift, not quite true, as valve face angle and valve stem dimensions have not been used, but these would have similar affect to all values.

Stock Inlet valve = 33.5mmDia = 105.257 Circumference
1 mm oversize = 34.5mmDia = 108.399 Circumference

camshaft listed HKS , other makes may have higher lift and longer duration:

Camshaft type lift mm dif from stock lift mm
Stock Inlet = I 8.8mm =0.00mm
264 I 9.0mm =0.20mm
272 I 9.2mm =0.40mm

Cam lift valve mm C Area
Stock cam
I 8.8mm lift stock valve = 33.5mm x 105.257 = 926.2616
I 8.8mm lift over size 1mm = 34.5mm x 108.399 = 953.9112

264
I 9.0mm lift stock valve = 33.5mm x 105.257 = 947.313
I 9.0mm lift over size 1mm = 34.5mm x 108.399 = 975.591

272
I 9.2mm lift stock valve = 33.5mm x 105.257 = 968.3644
I 9.2mm lift over size 1mm = 34.5mm x 108.399 = 997.2708

As you can see that, the 1mm oversize valves give better than 264 camshafts if using the area to compare.
The massive increase when using 272 with 1 mm oversize valves is the area for big bhp or low boost big bhp, as the decrease in the restriction, would be reduce, boost just over powers the restriction, but with heavy penalty’s

Kris · **Posted:** Sat Dec 17, 2005 11:17 pm

Interesting read Jon.

However it is my humble understanding that adding say a 272 camshaft will push the power up towards the top of the rpm range, thus necessitating to rev the engine to gain the maximum from it.

If the goal was torque rather than outright bhp, (as we all know large bhp can be had due to large rpm), I wonder what the solution would be?

I doubt this would be large cams? Maybe high lift cams with a shorter duration? Maybe even coupled with your suggestion of larger valves?

I notice that HKS manufacture a 256 cam which would be more suitable? iirc they go crazy and can have a lift of ~10mm!

datajon · **Posted:** Sun Dec 18, 2005 12:09 am

Kris No need for you to eat any humble pie.

10mm, umm, drag monster spec, running near hydraulic lock.

Remember one thing, higher rpm = less valve opening time, less time for every thing that goes on though the engine cycles.

There’s me thinking 9.0mm with 1mm oversize valves would be a good choice.

Think this would allow good bhp, and more importantly, Mr Torque.

It depends if you want a drag car for 10 seconds or a drivable car with power.

The rally cars had a limit of give or take 300 bhp, with torque over 400, this allows for a much better drivable vehicle, still reach similar top speed.

My 1st experience with my 1st car build, engine etc I was very young, and made some buck ups on the way.

Built a few ford Kent xflow engines. Various spec’s, but 2 come to mind 1st,using full race cam, another with a full rally cam, used the same big valve heads as, with twin 45’s, tubular manifold’s, the lot. Full spec on a mk2 escort, very nice, until...a long length of hedge got in the way. Thanks to the roll cage, or that would have been it, for sure. Do 145 mph with the correct gearing.

The race spec was great, would rev 8800 no worries, scream like hell in the night, but had nothing below 5k that’s when it kick, all lightened, the lot, but very painful to drive on the road.

However, the rally cam, well, totally different, top rpm, 7800, but power from 2500, all they way, had a dyno at Jan speed 183 bhp on 1800cc on the wheel, not bad, but you could drive it around every day if you wanted.
As for the race cam, well the engine let go best thing to happen, otherwise I would never of-tried the rally cam.

So I would say a mid range cams, with bvh, with suited hardware would give best power and drivable to boot.

These 4 wheel drives need the torque, if you have A & B roads everywhere.

Diceman · **Posted:** Tue Dec 20, 2005 10:53 pm

heh, whilst you are on the subject of cams :-
I suggested to a few guys abroad about looking at the 3S-GE cam specs compared to teh 3S-GTE. Some good info they have found and passed back to me :-)

2. gen 3SGE (165ps):

In: 244deg, 8.5mm lift (timing 7/57)

Ex: 244deg, 8.5mm lift (timing 57/7)

2. gen 3SGTE (225ps):

In: 236deg, 8.2mm lift (timing 8/48)

Ex: 236deg, 8.2mm lift (timing 56/0)

3. gen 3SGE A/T (170ps):

In: 240deg, 8.7mm lift (timing 7/53)

Ex: 240deg, 8.2mm lift (timing 53/7)

3.gen 3SGE M/T (180ps):

In: 252deg, 9.8mm lift (timing 7/65)

Ex: 240deg, 8.2mm lift (timing 53/7)

3.gen 3SGTE (245ps):

In: 240deg, 8.7mm lift (timing 7/53)

Ex: 236deg, 8.2mm lift (timing 50/6)

Gary ST165 · **Posted:** Tue Jun 20, 2006 3:58 pm

following on from JPs post, a write up from alltrac.net:

3sge st182 na cams into a st185 3sgte head.

http://alltrac.net/phpBB2/viewtopic.php ... highlight=

Diceman · **Posted:** Tue Jun 20, 2006 5:48 pm

Nice info Gary. So 3SGE inlet manifold & cams :-)

mook · **Posted:** Wed Jun 21, 2006 10:55 am

The guy sorting my head has found that the hi-lift cam option on a gen 2 head would mean an awful lot of work on the valvetrain to allow for the extra movement. We're going to stick with Piper's 264 cams but go for Ferrea 1mm oversixed exhaust valves, together with the other fettling of the head itself. He mentioned the head was well designed and certainly one of the better ones he'd come across, so top marks to Toyota for that, but with a little bit of work it should, as per Jon's info, help provide decent torque and a drivable road set-up. I'm also hoping that with the Motec added into the equation, my torque should shoot up

Will obviously report back with results once it's all sorted.

TrackToyFour · **Posted:** Wed Jun 21, 2006 1:13 pm

Mook, if you go for the 1mm oversize Ferrea valves you will need to fit larger valve seat inserts. There's not enough meat on the standard inserts to take the extra machining required.

HTH

mook · **Posted:** Thu Jun 22, 2006 12:05 pm

Don > Thanks for the info mate, I'll pass it on to my head builder

Diceman · **Posted:** Sun Oct 26, 2008 12:33 pm

Seems both Piper and Cat Cams have some interesting specs. Can't find much on Cat Cams at teh moment but I have seen specs detailing 10-11mm of lift!

Piper Cams:-
Product Code: TOYSGTBP270-Ex
Details :

Power band : 2000-6500rpm ; Power Increase : 10BHP ; Inlet duration : 260 deg ; Exhaust duration : 260 deg ; Inlet valve lift : .369"/9.37mm ; Exhaust valve lift : .367"/9.32mm (Valve lifts quoted assume a rocker ratio of 1:1) ; Timing (Inlet open - close) / (Exhaust open - close) : 20-60/60-20 ; Inlet full lift (ATDC) : 110 deg ; Exhaust full lift (BTDC) : 110 deg ; Valve clearances : Inlet = .010"/.25mm ; Exhaust = .012"/.30mm

Product Code:

TOYSGTBP300-Ex
Details :

For use with shim under bucket type followersPower band : 2500-7000rpm ; Inlet duration : 272 deg ; Exhaust duration : 272 deg ; Inlet valve lift : .430"/10.92mm ; Exhaust valve lift : .428"/10.87mm (Valve lifts quoted assume a rocker ratio of 1:1) ; Timing (Inlet open - close) / (Exhaust open - close) : 28-64/66-26 ; Inlet full lift (ATDC) : 108 deg ; Exhaust full lift (BTDC) : 110 deg ; Valve clearances : Inlet = .010"/.25mm ; Exhaust = .012"/.30mm

Product Code:

TOYSGTBP285-Ex
Details :

Power band : 2500-7000rpm ; Inlet duration : 264 deg ; Exhaust duration : 264 deg ; Inlet valve lift : .400"/10.17mm ; Exhaust valve lift : .398"/10.12mm (Valve lifts quoted assume a rocker ratio of 1:1) ; Timing (Inlet open - close) / (Exhaust open - close) : 22-62/62-22 ; Inlet full lift (ATDC) : 110 deg ; Exhaust full lift (BTDC) : 110 deg ; Valve clearances : Inlet = .010"/.25mm ; Exhaust = .012"/.30mm

GT4DC portal GT4DC Information WIKI

Camshafts, Bigger valves

Who is online