T-Series heads

[metcap]

well I hear this alot but what is catagorized as a turbo cam?

[NME308]

Hi there metcap,
Typically a turbo cam is characterised by wide lobe separation to limit valve open overlap.
My race car ran a 106 degree lobe separation cam when still naturally aspirated (damn grumpy bugger too!!! ) and with the twin turbo setup we had 114 degree lobe separation.
Due to relatively tame duration specs my 3TC turbo cam is ground on 110 lobe separation and still has bugger all valve open overlap.

Cheers,
Jason

[metcap]

Hi there metcap,
Typically a turbo cam is characterised by wide lobe separation to limit valve open overlap.
Cheers,
Jason

so naturally you can tune the cam lobe separation on a dohc right?

[MorGo]

Never heard an explanation what makes a "turbo" cam.. Mostly BS and others just "know it all,never done one"
What works in NA will work boosted! Of course if you have a setup that have exhaust backpressure 3:1 to boost you need something else but that is a wrong set-up!! Well designed builds have the pressure ratio other way (and NO,they are NOT laggy!)
When exhaust pressure exceeds boost the torque just fall down.At that point you either are happy with power or can go strategy to increasing boost for more power.You may gain a little but that's a dog chasing the tail..
When more boost don't increase the power you know that either the turbo is maxed out or have exessive backpressure.
If the max power rpm is below the NA engines max rpm there is something wrong..

[NME308]

MorGo I hate to have to say it but you sir are full of it...

People like you who parrot the 'modern' turbo philosophy have absolutely no idea how good a properly boosted engine can really work! If you genuinly build an engine for boost it does not have N/A specs. Yes I am well aware it is done with moderate success however the modern idea of adding boost to a high performance N/A engine leaves 200% sitting on the table untouched!!!

Cheers,
Jason

[MorGo]

Still waitin the explanation of "turbo cam"..

[NME308]

so naturally you can tune the cam lobe separation on a dohc right?

Yes you can - of course to state the bleeding obvious you need adjustable gears though!


Cheers,
Jason

[toyota1515]

Still waitin the explanation of "turbo cam"..

The reazon or exPlanation of the turbo cam is for this make the preassure of the boosted charge not leak tru the very small time both valves are open at the same time, so it does its work properly,
ASSUMING WE GOT A PERFECT SETUP wich we never gonna have, but the best we try the best it works

Remember, each and every different engine tunner/builder will have their own way of doing stuff around but not all got fast and powerfull engines/setups, plus all depends on the use intentions of the engine u build, no mater if is a street, drag, or road course!

[ctrain]

im waiting on a reply back about a possible 3t block with a crank to start my project, i have already bought a 2t head thats been reconditioned for a pretty cheap price, im going with eagle rods and 7.5 comp wiseco turbo pistons, I may be running it non turbo until i can gather up the money, but will it run like normal? lose power maybe? fuel comsumption be bad?

[J-M kujala]

fuel consumption is not good as, and loose a little power... maybe a little more "laggy" turbo 7.5 and stock 8.5 compression, there is not huge gain at 7.5...

[NME308]

Hi Callum,
You will be down approx 6% on power and torque over as opposed to running standard 9:1 compression as found normally on the N/A 3TC. Any efficiency mods i.e. head porting, cam, intake, and exhaust etc will all work as per normal however the engine will want plenty more timing so give it what it needs and you will be fine.

My 7:1 comp engine will pull around 108rwhp given boost (or more accurately pressure ratio) is the multiplier. Anyhow with the 108HP my little car can quite comfortably get out of its own way off boost and is far more lively than my original 2T worked N/A engine from some years back.

Cheers,
Jason

[ctrain]

hmm 6% i like that exact figure, would it be worth it to keep the bottom end all stock but with new calico bearings, then when i go to turbo it put in the new rods and pistons, it will still have the worked head on it which will be ported or match ported (someone explain match ported please?) bronze valve guides, bigger valves (42mm) double valve springs, and i think thats all i can do to head except buy a billet racing one, is there anything else i can do to the head or is that it?