dohc. ONE pully Options

[freakyre33c]

the 5sfe have dohc but one cam is driven by the belt, and that cam drives the other cam, why is it set up like this , why not just two pullys ? what are advantages and disadvantages?

[alltracman78]

It depends what you are trying to do......................................................
The 5SFE wasn't designed for high rpms.
It was designed for low rpm power. In which that particular setup works quite well..................
The narrow design hurts high rpm performance, weather it's NA or FI.
Look at Mannys 5SFTE. Wonder why he's making more torque? At lower rpms?.

[Kwanza26]

It depends what you are trying to do......................................................
The 5SFE wasn't designed for high rpms.
It was designed for low rpm power. In which that particular setup works quite well..................
The narrow design hurts high rpm performance, weather it's NA or FI.
Look at Mannys 5SFTE. Wonder why he's making more torque? At lower rpms?.

I don't think you understand what I'm saying. There's no way to make additional n/a power (not talking about making stockish power here) in a 4 cylinder without revving the engine... PERIOD... regardless of the head. Case in point... how many 1.6 to 2.0 liter 4 bangers do you see making 200hp n/a with a 6200 rpm redline? None.

In the case of the 5SFE... it can't rev because the head doesn't breathe well at higher rpms (makes it redundant to rev) nor does the stroke ratio like being revved (stress peaks = torque loss)... true enough... but forced induction changes the game. The power potential isn't so much limited by the head with forced induction, as it is limited by how much you boost (the set-up). The only thing the FE head affects strongly, is where that power is located... but the more torque you have, the less you have to worry about "where" power comes it the strongest. To further elaborate this point... think gearing.

FE head = bad n/a platform... great F/I Platform... excellent daily driver
GE head = great n/a platform... great F/I platform... ehh daily driver (TVIS/ACIS for the daily driver)

[alltracman78]

It depends what you are trying to do......................................................
The 5SFE wasn't designed for high rpms.
It was designed for low rpm power. In which that particular setup works quite well..................
The narrow design hurts high rpm performance, weather it's NA or FI.
Look at Mannys 5SFTE. Wonder why he's making more torque? At lower rpms?.

I don't think you understand what I'm saying. There's no way to make additional n/a power (not talking about making stockish power here) in a 4 cylinder without revving the engine... PERIOD... regardless of the head. Case in point... how many 1.6 to 2.0 liter 4 bangers do you see making 200hp n/a with a 6200 rpm redline? None.

In the case of the 5SFE... it can't rev because the head doesn't breathe well at higher rpms (makes it redundant to rev) nor does the stroke ratio like being revved (stress peaks = torque loss)... true enough... but forced induction changes the game. The power potential isn't so much limited by the head with forced induction, as it is limited by how much you boost (the set-up). The only thing the FE head affects strongly, is where that power is located... but the more torque you have, the less you have to worry about "where" power comes it the strongest. To further elaborate this point... think gearing.

FE head = bad n/a platform... great F/I Platform... excellent daily driver
GE head = great n/a platform... great F/I platform... ehh daily driver (TVIS/ACIS for the daily driver)

I understand EXACTLY what you are saying.
My point is, it's not just NA. If you throw a turbo on there, you have the EXACT same problem. It won't make the same hp as a G head, all mods being relative. It will make more torque.
You can bump the torque a bit, granted not as much as you can raise the hp with higher rpms.
But the point of the F head is to make power at low rpms. FI or not.

I agree it's not a good NA platform, but the same power blocks are there if you go FI [relative of course].

[Kwanza26]

I understand EXACTLY what you are saying.
My point is, it's not just NA. If you throw a turbo on there, you have the EXACT same problem. It won't make the same hp as a G head, all mods being relative. It will make more torque.
You can bump the torque a bit, granted not as much as you can raise the hp with higher rpms.
But the point of the F head is to make power at low rpms. FI or not.

I agree it's not a good NA platform, but the same power blocks are there if you go FI [relative of course].

Then why are we even discussing? =P

I still do say the FE head is as good as the GE head in boosted form because the amount of horsepower you shoot for is only limited by the amount of boost. The torque is ALWAYS there with boost, so picking between FE and GE is simply a matter of where in the powerband you'd prefer to race in. Take for example paradiseracing.com's AE86... powered by a turbo'ed 2RZFE. It's very possible to tune for horsepower. Another good example that comes to mind is the Scion tC's 2AZFE. In stock trim... makes 160 horses 160 ftlbs of torque. With the TRD supercharger, makes more horsepower than torque (trd estimates around 200hp and 180 ftlbs of torque... scion guys dyno around 180-190whp with 160-70 some odd torque at the wheels)! It's more so a matter of the turbo and tune.

then again... this is the n/a forum and n/a tuning is pretty much out of the question for the FE head.

This post has been edited by Kwanza26: Aug 20, 2006 - 12:04 AM

[alltracman78]

Then why are we even discussing? =P

I still do say the FE head is as good as the GE head in boosted form because the amount of horsepower you shoot for is only limited by the amount of boost. The torque is ALWAYS there with boost, so picking between FE and GE is simply a matter of where in the powerband you'd prefer to race in. Take for example paradiseracing.com's AE86... powered by a turbo'ed 2RZFE. It's very possible to tune for horsepower. Another good example that comes to mind is the Scion tC's 2AZFE. In stock trim... makes 160 horses 160 ftlbs of torque. With the TRD supercharger, makes more horsepower than torque (trd estimates around 200hp and 180 ftlbs of torque... scion guys dyno around 180-190whp with 160-70 some odd torque at the wheels)! It's more so a matter of the turbo and tune.

then again... this is the n/a forum and n/a tuning is pretty much out of the question for the FE head.

We are discussing because you don't seem to understand what you are saying.

And FE head is not as good as a GE head for HIGH RPM power. FI or not. Of course you can make alot of power with FI on a FE head. But it WILL NOT be as much as a GE head at high rpms, all mods being equal. PERIOD.

A FE head takes the power and moves it south.
FI or NA. You can play with it quite a bit more with FI, but it's still there.

You CAN make decent power with a FE head, even in NA.
It is all in where you want the power to be.
If you are looking for max hp, or high rpm power, a FE head wont' do you as well as a GE head.
BUT, if you are looking for a larger area under the curve, or power at low rpms, a FE head CAN BE UTILIZED .

Compare the 22RE [technically not a FE head, but it is designed for low rpm power, just like the FE heads] and the 3TGE.
When they raced Celicas in the early 80s with these 2 engines, the 22RE powered cars were FASTER than the 3TGE ones. Because they had more torque and useable power. They weren't tuned for power in a [relatively] small band up top. They had MUCH more useable power.
A PERFECT example of how a NA FE makes more [useable] power than a NA GE.
AT LOWER RPMS.

[Kwanza26]

We are discussing because you don't seem to understand what you are saying.

And FE head is not as good as a GE head for HIGH RPM power. FI or not. Of course you can make alot of power with FI on a FE head. But it WILL NOT be as much as a GE head at high rpms, all mods being equal. PERIOD.

Who's to say the FE head bad for FI? Or at the very least not as good as the GE? There are many many cases of the FE head able to produce and maintain power comparable to GE heads in the high rpms. Under forced induction, the FE head is no longer limited by high-rpm breathing... because the breathing is done by the turbo/supercharger. Unfortunately, there just aren't too many people who have purpose built FE heads... but it's there. The head does have inherit disadvantages from the get go... but like I keep saying, under boost with the right set-up... horsepower can be pushed deeper into the rpms.

Check out this dyno of a stock scion tc versus a supercharged scion tc...

Stock n/a form (blue) makes more torque than horsepower. Supercharged form (red) makes more horsepower than torque... and when you look at the s/c torque curve, this thing can easily maintain that torque/horsepower towards 6.5-7K rpms before it significanly declines (considering how jumpy the curve is... could use some tuning also), while the n/a torque curve starts to decline by 4.5k rpms.

A FE head takes the power and moves it south.
FI or NA. You can play with it quite a bit more with FI, but it's still there.

True for n/a... not quite true for FI because the reason it pushes power south is because it reaches its peak velocity very quickly. This is not a factor when fully tuned and boosted because the breathing and velocity is not done solely by the head.

You CAN make decent power with a FE head, even in NA.
It is all in where you want the power to be.

On this point... no. n/a horsepower with small displacement = REVS. You can open up the engine a little bit with extreme mods, but performance gains are negliable. Take Jim Snodgrass as the prime example... the best breathing mods you can do to the engine and power still fails by 4500 rpms. He made what... 145-150 whp? Bang for the buck? Not worth it. That's like 20-30hp over stock for his thousands spent in modifications.

If you are looking for max hp, or high rpm power, a FE head wont' do you as well as a GE head.
BUT, if you are looking for a larger area under the curve, or power at low rpms, a FE head CAN BE UTILIZED .

This is only relative to a person's taste about the engine's feel. No true n/a performance 4 banger is all about making low-end torque unfortunately. I have nothing against the FE head... bu it's simply not designed with performance in mind. When we speak of performance... we speak of horsepower. Don't even think about mentioning torque curves unless you got a load of it.

Compare the 22RE [technically not a FE head, but it is designed for low rpm power, just like the FE heads] and the 3TGE.

The 22R head had rather huge valves with rockers, allowing it to SPIN... and was built like a tank. It made more power because the strength of the design allowed the engine to maintain revs... and yes... those suckers revved. The 3T's were simply a smaller motors and thier G heads weren't really any good, likewise the 18RG was not that great either. The first good G head was on the 4AG.

When they raced Celicas in the early 80s with these 2 engines, the 22RE powered cars were FASTER than the 3TGE ones. Because they had more torque and useable power. They weren't tuned for power in a [relatively] small band up top. They had MUCH more useable power.
A PERFECT example of how a NA FE makes more [useable] power than a NA GE.
AT LOWER RPMS.

Here's the rundown on typical track guys from the days I used to race (late 90's early 2000's). High-end horsepower is better for track racing, where you slam through the gears and can keep the rpms high. This is mostly club racing or formula racing or something along those lines. Fatter torque bands with more useable torque is better for short tracks, or where you maintain gears longer. Think autoX or rally.... however even in rally they mate big torque with short gearing most of the time to keeps revs up. High torque handles the different traction situations better than big horsepower. Each to his own. What works for what is a matter of the track and conditions.

In the end... it's purely a matter of prefrence... and NO... I still say building an n/a motor out of an FE 4 cylinder is still a waste of time. The only thing we don't agree on is the FE head's capability to make top-end horsepower... but refer back to that 2AZ dyno and re-think it a bit...

This post has been edited by Kwanza26: Aug 24, 2006 - 11:05 PM