5e-fhe pistons... Turbo friendly?

[abently]

Yay or nay? Please provide evidence (links, first hand experience etc etc)

As to why the question, I'm not interested in the 8.2:1 CR forged pistons will give me....

Ta

[NME308]

Yay or nay? Please provide evidence (links, first hand experience etc etc)

As to why the question, I'm not interested in the 8.2:1 CR forged pistons will give me....

Ta

Yeah I guess 8.2:1 is a bit low if your tuner doesnt know how to tune...

On the other hand you need to state a bit more of your intended purpose and HP goals etc.

Most engines will handle a mild boost up with careful tuning i.e. aftermarket ecu and good dyno operator etc. Even an engine with the best forged internals will not last with a poor tune!

Cheers,
Jason

[abently]

Yeah I guess 8.2:1 is a bit low if your tuner does know how to tune...

Fixed.

100Hp per 0.33L

I agree with your last statement. I have since googled a bit more to see how far others have pushed these and am betting it will hold fine, just keep knock down to zero and plenty of ring gap as per usual.

[TERRA Operative]

The stock 5E-FHE pistons are cast.... At least ceramic coat them to keep the heat out.

The aftermarket forged ones are 5E-FE pistons, exactly the same as 5E-FHE except for the lower crown height for lower compression.
I've looked for forged 5E-FHE and not been too lucky so far, if you find any, let me know!!

[NME308]

So I gather from above you are hoping to make a nads n all screamer then!

100hp per .33L and from a quick google the 5EF is 1.5 litres gives an aimed target of 450HP!

Methinks the word cast piston and 303HP/Liter engine capacity do not mix... At least not for long!

Going back to the compression thing - most people fail to realize that there is a tradeoff of torque happening with higher compression for a given fuel octane. What I mean is that the higher the static compression ratio the lower the boost which can be run and or the less timing which can be run. An engine with low compression can handle much more boost with plenty of timing for a given fuel and hence has much higher torque figures than a high compression motor.
Most cars make plenty more rwhp on a dyno than they show at the drag strip on the Moroso HP calculator (weight shifted horse power). My brother and I run what to most people is a stupidly low 7.0:1 static compression ratio and tune accordingly. Last weekend we dyno'd 786rwhp at 6000rpm with a tune which made 975 Moroso HP at the dragstrip 1 week earlier. The difference is the massive torque a low compression boosted motor can put out. The dyno guys were gnawing their nails cos we were 1st car up for the weekend of a dyno shootout and they thought we would overrun/melt their 1000rwhp rated dyno based on the dragstrip HP we made!
I also run 7.0:1 compression in my 1.8 3T motored celica daily driver. It is a beautiful car to drive and I have yet to find a hill on the highway to make top gear labour i.e. 2400km to Dubbo and return from Rockhampton!
You may be right in thinking that there is a special skill in tuning boost into a high compression motor but I'll take torque anyday when you are working with small cube engines!

By the way if it is not top secret then I'd love to know more of what you are planning to do with this lil screamer. There is a bloke up my way here who has a 1.6 fagda mx5 which he has jammed full of the best internals and it goes somewhere in the 300+rwhp range. Unfortunatly a hose to the map sensor blew off on the dyno a couple of months back and the rods all resized themselves...

Cheers,
Jason

[abently]

The stock 5E-FHE pistons are cast.... At least ceramic coat them to keep the heat out.

The aftermarket forged ones are 5E-FE pistons, exactly the same as 5E-FHE except for the lower crown height for lower compression.
I've looked for forged 5E-FHE and not been too lucky so far, if you find any, let me know!!

You mean the 4E-FE forged pistons? I.e. -1mm crown.

[abently]

Going back to the compression thing - most people fail to realize that there is a tradeoff of torque happening with higher compression for a given fuel octane. What I mean is that the higher the static compression ratio the lower the boost which can be run and or the less timing which can be run. An engine with low compression can handle much more boost with plenty of timing for a given fuel and hence has much higher torque figures than a high compression motor.

Boost does not equal HP.......

I agree with your comments on the timing tradeoff, but if you are running large cams, that high static compression ratio isn't really as high as you think.

[NME308]

Boost does not equal HP.......

I agree with your comments on the timing tradeoff, but if you are running large cams, that high static compression ratio isn't really as high as you think.

Running large cams will definatly bleed off some of that high static compression ratio... At idle and punting round town! Once you get the engine into the cams efficiency range that high static compression ratio is still high!

I also wasnt trying to say that boost equals horsepower. Being able to run a higher boost with low compression may actually register lower horsepower as per my own example above, the torque available however is much higher and torque is what actually moves objects like cars! For me tuning a 350cube turbo V8 I choose to run with low compression to give bulk torque to shift my 1630kg car. If I had a 600cube big block turbo V8 I would run 10:1 or higher compression to kill off some of that tire melting torque and build more highly strung horsepower so I could actually launch it...

Cheers,
Jason

[abently]

HP and torque are intrinsically linked, as you well know... so I have a hard time understanding how one can exist without the other per see.

If you are suggesting, under the area HP or Torque is more important than peak HP or Torque, I wholeheartedly agree.

Camshafts play a big part in setting this power-band, as much as the Turbo chosen does.

I really have to see two exact turbo motors, with different static CR's, on an engine dyno to believe in the theory of less CR is a good thing, because everything I have seen has said otherwise..

If I was having to reduce timing severely and boost (airflow), to keep knock down to a minimum, then at that stage I would say less static CR should produce more torque and power across the board.

[NME308]

HP and torque are intrinsically linked, as you well know... so I have a hard time understanding how one can exist without the other per see.


I really have to see two exact turbo motors, with different static CR's, on an engine dyno to believe in the theory of less CR is a good thing, because everything I have seen has said otherwise..

Horsepower is a measure of rpm x torque divided by a constant (set figure). The relationship between these figures will determine how well the engine performs in different conditions. The higher in the rpm range an engine can make its torque then the more horsepower will be recorded on a dyno. However the lower in the rpm range an engine can begin making peak torque (or close to) and the wider rpm band that this torqe can be held makes for an engine which can efficiently move an object like a car.

Lets take the math on two engines.
Engine 1 makes 330ft lbs torque at 8000rpm. We take the formula of HP = torque x RPM % 5252 giving 487HP - not bad if this is a small engine!

Engine 2 makes 500ft lbs torque at 5000rpm. Using the formula again it comes out at 476HP - down 11hp in the eyes of someone chasing the all important dyno figure!

I'll take engine 2 which has been built in a manor to put out large amounts of torque for the purpose of drag racing a car. I'd take engine 1 if I was chasing dyno numbers as it has more potential for racing dyno's!

At the end of the day chasing dyno figures can be fun! I am a firm believer after some years of experience that building and tuning engines for dyno work and drag racing are two different art forms...

Let me explain my own theory. Two engines with otherwise identical specs apart from compression and lets say pump fuel. An engine with lower compression obviously squeezes the mixture much less than a high compression motor hence the combustion event is milder and most likely will yeild less power. Now if we start to wind up boost the high compression motor will likely start to require timing retard to avoid detonation as cylinder pressures rise and will reach a point where gains are no longer plausable. On the low compression motor far more boost can be applied before the same point of destructive cylinder pressures are reached. The lower compression motor has a far greater volume of fuel and air in the cylinder than the high compression motor for a given cylinder pressure. More fuel and air each combustion event equals more useable power! My experience of this type of engine is the torque is developed at lower rpm hence will not necessarily show up the all important HP numbers on a dyno!

Cheers,
Jason

[TERRA Operative]

You mean the 4E-FE forged pistons? I.e. -1mm crown.

4E-FE are low compression (dished), 5E-FE are in the middle (flat) and 5E-FHE are the highest (domed).

[abently]

4E-FE are low compression (dished), 5E-FE are in the middle (flat) and 5E-FHE are the highest (domed).

Now that makes sense with everything I've seen. Thanks!

I assume you are talking about CP 5efe Forged pistons?

[abently]

Lets take the math on two engines.
Engine 1 makes 330ft lbs torque at 8000rpm. We take the formula of HP = torque x RPM % 5252 giving 487HP - not bad if this is a small engine!

Engine 2 makes 500ft lbs torque at 5000rpm. Using the formula again it comes out at 476HP - down 11hp in the eyes of someone chasing the all important dyno figure!

I'll take engine 2 which has been built in a manor to put out large amounts of torque for the purpose of drag racing a car. I'd take engine 1 if I was chasing dyno numbers as it has more potential for racing dyno's!

At the end of the day chasing dyno figures can be fun! I am a firm believer after some years of experience that building and tuning engines for dyno work and drag racing are two different art forms...

Let me explain my own theory. Two engines with otherwise identical specs apart from compression and lets say pump fuel. An engine with lower compression obviously squeezes the mixture much less than a high compression motor hence the combustion event is milder and most likely will yeild less power. Now if we start to wind up boost the high compression motor will likely start to require timing retard to avoid detonation as cylinder pressures rise and will reach a point where gains are no longer plausable. On the low compression motor far more boost can be applied before the same point of destructive cylinder pressures are reached. The lower compression motor has a far greater volume of fuel and air in the cylinder than the high compression motor for a given cylinder pressure. More fuel and air each combustion event equals more useable power! My experience of this type of engine is the torque is developed at lower rpm hence will not necessarily show up the all important HP numbers on a dyno!

Cheers,
Jason

Thanks, that makes sense with what I know also.

[oldcorollas]

it is easy and not that expensive to have pistons made to your specifications (by not that expensive, i mean over the cost of buying new pistons anyway, and the machining to fit them properly)

[abently]

it is easy and not that expensive to have pistons made to your specifications (by not that expensive, i mean over the cost of buying new pistons anyway, and the machining to fit them properly)

I will inquire about such and see what response I get back OC.

Though I do have an itch to see how far you can take a very factory Toyota only motor.. lol, we'll see.