In for the long haul Ultimate NA build thread.

[FRS Justin]

Originally Posted by celek

Only downside is valve to piston clearance. The longer they are open more chance of interference. Stock pistons probably wont work on every cam. Even HKS says you can not use their cam with stock pistons, they say you should buy the high capacity kit.

Hey Chris


I was researching cams for my backup motor (yes another one) and found this . Excellent info on FA20 camshaft specs. It has piston to valve contact clearances.


I know it won't apply 100% because of your pistons but it might help if you decide to go with a custom set of cams like I am.


http://dsportmag.com/the-tech/tomei-...0-flat-four/3/

[Captain Snooze]

Originally Posted by jarnojvv

Just a question: how does weight reduction increase whp? It surely only improves response and feeling. It would be interesting to see how much focused mods can reduce the driveline friction to increase the real whp.

[FRS Justin]

Originally Posted by jarnojvv

Just a question: how does weight reduction increase whp? It surely only improves response and feeling. It would be interesting to see how much focused mods can reduce the driveline friction to increase the real whp.

Google is a wonderful thing....


http://www.w8ji.com/rotating_mass_acceleration.htm


copy and paste to browser

[celek]

Originally Posted by jarnojvv

Just a question: how does weight reduction increase whp? It surely only improves response and feeling. It would be interesting to see how much focused mods can reduce the driveline friction to increase the real whp.

If you roll a 200lb boulder up a hill it takes energy. Now if you reduce its mass to say 50lbs it takes less energy and can be rolled faster.
Same amount of power put behind it the less the person has to work same with the engine.

Still making 200HP stock but reduced weight especially in rotating assembly results in less power lost in the drive train. Less parasitic loss in the drive train interpolates to more WHP

[churchx]

celek: only losses in friction of gears/bearings and tire-road affect whp readings. And those are mostly same with or without lightened rotational components. Change of rotational mass affect only time at which certain speed is reached, not how much energy is needed once it gets up at said speed. In your example if you move it to dyno, then it's not the wheel of 200lb or 50lb weight, but rather that dyno brakes car wheels at four time the force, which is not the case. With same dyno "braking" readings should be same for both 200lb & 50lb wheels, with exception of how long heavier one was spun up/accelerated to max speed.

[celek]

Originally Posted by churchx

celek: only losses in friction of gears/bearings and tire-road affect whp readings. And those are mostly same with or without lightened rotational components. Change of rotational mass affect only time at which certain speed is reached, not how much energy is needed once it gets up at said speed. In your example if you move it to dyno, then it's not the wheel of 200lb or 50lb weight, but rather that dyno brakes car wheels at four time the force, which is not the case. With same dyno "braking" readings should be same for both 200lb & 50lb wheels, with exception of how long heavier one was spun up/accelerated to max speed.

Really depends on perception but I agree. One of the things in my build is REM polishing of the gears, technically not only lightening the gears by removing tiny bits of rough material including removing friction causing micro peaks. As friction generates heat removing them reflects prolonging transmission life.

[FRS Justin]

Here is another article that should make everyone happy on the light weight subject please read. so we can get back on topic.


http://www.uucmotorwerks.com/flywhee...heel_works.htm












How does a lightweight flywheel work? Amongst the majority, there are two schools of thought concerning light flywheels. The first is that they do not contribute to power output. The second is that they do. Which thought is correct? In fact both, in a way, are correct.

[solidONE]

I recall seeing a peak 1~2whp gain from just changing the stock wheel and tires with a lighter RPF1/RS3 tires, all else equal.

[Summerwolf]

A 1-2 hp "gain" is well within acceptable differences between runs. 1-2 hp on a dyno is literally not worth noting.

[solidONE]

Originally Posted by Summerwolf

A 1-2 hp "gain" is well within acceptable differences between runs. 1-2 hp on a dyno is literally not worth noting.

This is true, I was skeptical of the gain I was seeing but it was consistent under multiple pulls. I even remounted the factory wheels to confirm what I was seeing, and it was consistent.

[KoolBRZ]

Originally Posted by churchx

celek: only losses in friction of gears/bearings and tire-road affect whp readings. And those are mostly same with or without lightened rotational components. Change of rotational mass affect only time at which certain speed is reached, not how much energy is needed once it gets up at said speed. In your example if you move it to dyno, then it's not the wheel of 200lb or 50lb weight, but rather that dyno brakes car wheels at four time the force, which is not the case. With same dyno "braking" readings should be same for both 200lb & 50lb wheels, with exception of how long heavier one was spun up/accelerated to max speed.

They would show in the graph as a quicker ramp up to max HP. The low and mid-range HP would show improvements. There would be no difference to the final number however the drive-ability would be greatly improved.

[churchx]

KoolBRZ: was there in any dyno chart also time shown? In all were just whp/wtq at rpms. So how can it be shown in graph? Yes, acceleration would be quicker, yes one would notice that in driving .. but how would you see it in dyno graph?

[KoolBRZ]

Originally Posted by churchx

KoolBRZ: was there in any dyno chart also time shown? In all were just whp/wtq at rpms. So how can it be shown in graph? Yes, acceleration would be quicker, yes one would notice that in driving .. but how would you see it in dyno graph?

The low and mid-range parts of the dyno graph aren't tested static. They are tested on-the-rise. In other words, acceleration is shown in the graph UP TO the peak. It alters the shape of the visible ramp. Low acceleration shows as a gradual incline with a steep part at the end, while high acceleration shows as a steep angle right at the start, leveling off to a gradual incline at the end.

[Tim Radley]

Originally Posted by solidONE

It would be nice to know how much gains yielded by the cams themselves. I've gained about 30whp on "other changes" with stock cams, so when you say +25bhp with cams and 'other mods' its not saying too much.

Problem is there are two major design flaws in the intake system that really hold it back in N/A form. I've seen it in the datalogging from both road and dyno. Might print a new intake manifold over Christmas to test out as I want to leave the car in N/A form whilst i set the Holinger up.