Build opinions?

[SleepinLS]

I am tyring to decide on what to do with my 98spec ITR motor.
So far I have looked into Skunk2 pro1+ cams and gears, pro-series springs and retainers, pro-series standard size high compression valves, and skunk2's 70mm exhaust.
If you guys have any suggestions please let me know.
Thanks,
Brandon

[aznauticab0i]

port and polish that baby while its off

[Markusirealius01]

Port and polish that beast and get some Toda cams while youve got it apart.
Before you get that exhaust listen to it on the car. That thing get's freakin loud.

[SleepinLS]

Yeah port and polish is a must so ive been told. Any camshaft suggestions?

[SleepinLS]

Port and polish that beast and get some Toda cams while youve got it apart.
Before you get that exhaust listen to it on the car. That thing get's freakin loud.

Deep loud or raspy loud?

[Dave_B]

I think your a little ahead of yourself here. You'll never utilize the cams, valves or any of that without changing to higher compression pistons.

You might see a little bit of a difference, but not to much.

My build has JDM P30 pistons in and a Mugen HG to bring the compression up. For the head I have S2S2 cams, S2 Pro cam gears, Stage 2 P&P on the head and the chambers have also been reshaped.

You need to look into doing something for compression to utilize changing to big cams such as the S2 Pro series.

But, even before you start tearing it down and doing internal mods, what are your goals? Current mods? I would start with the bolt ons, Header, Exhaust and intake. Once you've got those, and still aren't happy then look for other options.

[Bbasso]

I would start with the bolt ons, Header, Exhaust and intake. Once you've got those, and still aren't happy then look for other options.

Yes!, Many many people are happy with just this Including myself. Start with the basics and then evaluate. But pick the parts wisely so that they don't limit the possible mods down the road.

[SleepinLS]

I think your a little ahead of yourself here. You'll never utilize the cams, valves or any of that without changing to higher compression pistons.

You might see a little bit of a difference, but not to much.

My build has JDM P30 pistons in and a Mugen HG to bring the compression up. For the head I have S2S2 cams, S2 Pro cam gears, Stage 2 P&P on the head and the chambers have also been reshaped.

You need to look into doing something for compression to utilize changing to big cams such as the S2 Pro series.

But, even before you start tearing it down and doing internal mods, what are your goals? Current mods? I would start with the bolt ons, Header, Exhaust and intake. Once you've got those, and still aren't happy then look for other options.

Yeah I really wasnt looking to build the bottem end yet, but as of right now I have an SMSP header, 3inch short ram (just sold the Jays racing CF intake), magnaflow 2.5 high flow cat, GReddy EvoII 60mm Exhaust (looking to upgrade) and an Exedy Stg.1 clutch.

I'm currently putting down 197whp and 137wtq on a mustang dyno. Don't get me wrong it's quick but i am looking to get a little more out of it mainly Tq. And I should probably get something better for tuning im using Crome:(

I also look into doing a JRSC supercharger kit, but i havent heard to many good things about using them on ITR motors?

But I'm still new with 4cyl. motors so I need your guys imput... what would you recommend?

[neo_]

I think your a little ahead of yourself here. You'll never utilize the cams, valves or any of that without changing to higher compression pistons.

Dave, that is a very common H-T like misinformation. Compression has very little to do with a cam's requirements. I am far from a fluid/physics major but this is my understanding of it.

Compression just creates power through combustion.

Cams control the duration and lift of the valve.

You would want to change the duration and lift of the valves only when your engine has a better intake/exhaust flow then stock and/or has more displacement.

Flow is directly related to the exhaust, header, head ports, intake manifold, throttle body, and intake. When you make your engine breath easier, you can take advantage of that and give the valves more duration and/or lift with aftermarket set of cams.

Displacement is based upon the bore and stroke. The engine is a basic air pump, and if you increase the displacement you'll be able to vacuum in and expel more air. Likewise, more duration and/or lift with bigger cams will take advantage of this siltation.

If you are running a fully stock induction, exhaust system, and stock displacement, and install a pair of bigger cams you will not benefit and may even loose power. As cams change up two things through duration and lift, velocity and flow of air. Too much duration and/or lift will lower the velocity/flow of air and you engine will actually induct LESS air then it did stock and possible even affect the atomization of the fuel with air. You can also make slightly more power with cams is indirectly by maximizing the atomization of the fuel with air by having a better higher velocity and more flow of air with bigger cams, however this is also a way how you can loose power if you over cam the engine as I just previously mentioned how.

Now if this interests you, look into how duration/lift affects flow, velocity and the direct equivalent to power. See what makes more power, flow or velocity, how more CFM will not always make more power if the velocity is not increased, and etc... Which just adds the more reason to choose your head porter very carefully, don't be fooled by raw CFM numbers as it is basically a noobyish marketing gimmick. It gets pretty technical in some areas but it is quite fascinating, at least to me.

Sorry for the long rant, hopefully this detailed explanation will help out future people trying to understand how cams work as there seems to be a large misconception of how you need more compression for cams, when you really don't. Maybe you or Rob can sticky this to help people understand how cams work.

-neo

[Bbasso]

me no sticky powars

yes you are right about compression , cams and output.
From my days of building chevy v8 (s) some of those guys had 8.0:1 with crazy cams, toilet bowl carbs, open headers and were putting out some serious power. Of course compression helps but only if the entire mix of parts is set right.

[neo_]

Yep, and with lower compression you are able to run lower octane safly and make the same amount of power if not more. Another myth is that more octane always creates more power. Which isn't true. I actually lost 5 WHP when I retuned my car on 100 octane unleaded compared to 93 unleaded on 12.5:1 compression setup. 95-97 Octane was the sweet spot for my 12.5:1 compression. Now, lets see if anyone can tell me why this is such.

[Bbasso]

... Cause higher octane is harder to ignite... Duh

[SleepinLS]

I think your a little ahead of yourself here. You'll never utilize the cams, valves or any of that without changing to higher compression pistons.

Dave, that is a very common H-T like misinformation. Compression has very little to do with a cam's requirements. I am far from a fluid/physics major but this is my understanding of it.

Compression just creates power through combustion.

Cams control the duration and lift of the valve.

You would want to change the duration and lift of the valves only when your engine has a better intake/exhaust flow then stock and/or has more displacement.

Flow is directly related to the exhaust, header, head ports, intake manifold, throttle body, and intake. When you make your engine breath easier, you can take advantage of that and give the valves more duration and/or lift with aftermarket set of cams.

Displacement is based upon the bore and stroke. The engine is a basic air pump, and if you increase the displacement you'll be able to vacuum in and expel more air. Likewise, more duration and/or lift with bigger cams will take advantage of this siltation.

If you are running a fully stock induction, exhaust system, and stock displacement, and install a pair of bigger cams you will not benefit and may even loose power. As cams change up two things through duration and lift, velocity and flow of air. Too much duration and/or lift will lower the velocity/flow of air and you engine will actually induct LESS air then it did stock and possible even affect the atomization of the fuel with air. You can also make slightly more power with cams is indirectly by maximizing the atomization of the fuel with air by having a better higher velocity and more flow of air with bigger cams, however this is also a way how you can loose power if you over cam the engine as I just previously mentioned how.

Now if this interests you, look into how duration/lift affects flow, velocity and the direct equivalent to power. See what makes more power, flow or velocity, how more CFM will not always make more power if the velocity is not increased, and etc... Which just adds the more reason to choose your head porter very carefully, don't be fooled by raw CFM numbers as it is basically a noobyish marketing gimmick. It gets pretty technical in some areas but it is quite fascinating, at least to me.

Sorry for the long rant, hopefully this detailed explanation will help out future people trying to understand how cams work as there seems to be a large misconception of how you need more compression for cams, when you really don't. Maybe you or Rob can sticky this to help people understand how cams work.

-neo

wow. im not gonna lie im a little confused, lol. so pretty much cams are all about duration and how much air gets into the motor.

[Bbasso]

so pretty much cams are all about duration and how much air & fuel gets into the motor at a certain time.

[Bbasso]

For more details: http://auto.howstuffworks.com/camshaft.htm