Interesting EG33 output comparison...

[Chiketkd]

Originally posted by SilverSpear
taking the engine alone, with no consideration the weight or so, I guess they could have produced an output of 260 hp very easy. you are comparing a 3.3L to 3.0 L why not comparing it to the 350Z ? with 280hp ? ... also IT'S A BOXER ENGINE FOR GOD'S SAKE !!! you can also compare the 3.0L 24Valves mercedes benz also, a smaller size engine with 217 - 224 HP and a torque BORN IN HELL.... so I guess the SVX's EG33 is like a pussy comparing to the others !!

Danny,

Like drivemusicnow and mbtoloczko were trying to explain, you really missed the point of my post. The SVX/EG33 was designed back in the late 80's by Subaru and released in '91 to the Japanese market initially... We're talking about technology that's over 15 years old.

Comparing the EG33 to engines in sports cars/sedans available today would not be a fair comparison as 15 years of technology & engineering advances have taken place. My goal was to have as close of a true apples-to-apples comparison as possible. The SVX was often pitted against these very same cars in magazine reviews, and it was in the same price range of all the cars I've compared it to.

BTW, 230hp out of 3.3L is still respectable these days. Lexus gets 215hp in their 3.0L IS300, and BMW gets 225hp in their 3.0L 330i...

-Chike

[drivemusicnow]

Originally posted by oab_au
All these engines are virtually the same. They all have a cylinder size of between 500 to 550 cc, all use a four valve, pent roof combustion chamber. All have fuel injection and tuned inlet and exhaust systems. Their torque producing capacity or volumetric efficiency will be very close. Nearly all engines follow the same design.

The difference between them is how the torque is to be used in the car to be produced. If it is to be a commuter or 'shopping trolley', the torque peak is placed at around 4000 rpm to give good low rpm performance and pick-up at legal speeds. If it is to be a sports type car with a 5/6 speed box, it will have the torque peak moved up to around 6000 rpm. Same engine, different HP results.

The designed peak torque rpm is set by placing the inlet valve fully opening position (lobe center) at the desired rpm for the torque peak to occure. Within reasion, the torque level will be the same, but as in the sports version, the HP will be higher, because the torque peak is occuring at a higher rpm.

To compare these type of engines, the torque curve is the most informative sorce. Is the curve peakey, or long and flat? The higher the rpm that the torque is produced, the peakey the curve is, as more reliance on resonate technology is used, as these are dependant on a particular rpm, the torque will fall off quickly either side of the peak torque rpm.

To get around the peakey nature of resonate tuning, we have versions with two tuned inlet tracts, a low range centered around 3500/4000 rpm and a higher speed tract at around 5000/6000 rpm. When this is used along with a variable inlet timing (it moves the lobe center to suit two different rpms) the torque peak can be spread over a wider range of engine speeds.

The SVX does it better at the low speed end with the inerta system, as it produces a far higher VE at low rpms than a low speed tuned system can.

Numbers don't tell you much about how the car will preform. The torque curve tell you everything.

Harvey.

Very true...

So how could we raise peak torque (thereby raising hp) and raise the redline of the engine... and which would give the best performance for a street driven application? Obviously the general consensus on these boards is that stock tuning is ultimate... (with the chip it flattens and increases torque curve, but tahts just doing something more tightly regulated that what could be done when the car was made)

How could you keep that bottom end, IRIS tuned torque, while raising the "other"/"real" peak torque in rpms

[SVXRide]

Originally posted by drivemusicnow


Very true...

So how could we raise peak torque (thereby raising hp) and raise the redline of the engine... and which would give the best performance for a street driven application? Obviously the general consensus on these boards is that stock tuning is ultimate... (with the chip it flattens and increases torque curve, but tahts just doing something more tightly regulated that what could be done when the car was made)

How could you keep that bottom end, IRIS tuned torque, while raising the "other"/"real" peak torque in rpms

More valve lift!!
-B

[oab_au]

While the gear box is going to change at the same rpms, regardless of the engine rpms, there is nothing to be gained by raising the rpm, that the peak torque is produced at. Unless it is fitted with a manual box, that could run into the higher rpms.

Increasing the valve lift is really the only thing that will increase the torque, and the acceleration, without resorting to pumping more air in. The valve sizes are big enough for the cylinder size, the ports are fine as they are, and the inlet and exhaust tracts are well suited to the overall design.

I think if you want to increase the preformance, you will have to forget the interferance design, and use bigger valve lift. Breaking a timing belt, though not unknown, is not something that would worry someone, that wants to get results. I would just replace it at a half distance. Most high preformance engines are interferance, just no way around it. If you are that worried about it, you should stay standard.

The lift now is 7mm inlet, 8mm exhaust, I think the difference in the lifts, is to do with the noninterferance bit. The inlet valve is 37mm, the exhaust 36mm. This looks like the bigger inlet would hit if given the same lift as the exhaust. I think the ideal cam to use, would have the same duration, with the inlet cam lift increased to 9mm.

This would keep the cost down to just two cam regrinds, instead of four. The results would be more torque, everywhere, an increase in HP, and the Inerta and Resonate tuning would work the same, as he duration remains the same.

The cam grinding can be done by reducing the base circle, or increasing the lobe height. If there is no lobe clearence problems, the latter would be the go. If there is a problem with the taller lobe hitting the sides of the follower well, reducing the base circle and fitting a 2mm shim under the follower would have to be done.

Nothing ventured, nothing gained.

Harvey.

[mbtoloczko]

Hey Harvey, I'm curious about thoughts on something related to what you wrote above. I've done quite a few calculations on predicting HP of the SVX motor based on engine size, air temperature, a/f ratio, and in order to get an answer of 230 HP at 5400 rpm, its always necessary to use a volumetric efficiency of 100% or more. So, I'm wondering how much there would be to gain by increasing valve lift. I think it would be interesting to try, but I just wonder how much there will be to gain.

[drivemusicnow]

What about making it an interference engine...

increase the intake lift to 8mm... 9mmif possible AND increase the compression ratio to 11, maybe 12:1... yeah, you'd be screwed if you broke the timing belt, but would the higher compression ratio be enough to bump out power output "significantly"?
Doming the pistons would obviously give you even less clearence... but how would that affect overall torque output

[Chiketkd]

Originally posted by oab_au
The lift now is 7mm inlet, 8mm exhaust, I think the difference in the lifts, is to do with the noninterferance bit. The inlet valve is 37mm, the exhaust 36mm. This looks like the bigger inlet would hit if given the same lift as the exhaust. I think the ideal cam to use, would have the same duration, with the inlet cam lift increased to 9mm.

This would keep the cost down to just two cam regrinds, instead of four. The results would be more torque, everywhere, an increase in HP, and the Inerta and Resonate tuning would work the same, as he duration remains the same.

Harvey,

Like Mychailo, I'm also interested in knowing the approx gains in hp & tq that might be returned if inlet lift was increased from 7mm to 9mm?

Having two cams ground instead of four would definitely save big $$$ as most shops in my area charge at least $100 per cam...

-Chike

[oab_au]

Originally posted by mbtoloczko
Hey Harvey, I'm curious about thoughts on something related to what you wrote above. I've done quite a few calculations on predicting HP of the SVX motor based on engine size, air temperature, a/f ratio, and in order to get an answer of 230 HP at 5400 rpm, its always necessary to use a volumetric efficiency of 100% or more. So, I'm wondering how much there would be to gain by increasing valve lift. I think it would be interesting to try, but I just wonder how much there will be to gain.

Hi mate, well that shows the effect that the resonate end of the inlet system has. At these rpms the exhaust tuning produces a negitive pressure in the cylinder, at the valve overlap peroid, when the inlet valve is starting to open. The low pressure starts the inlet flow, and the tuned inlet tract provides a negitive pressure in the cylinder at the end of the inlet peroid, to keep the filling going as the piston is moving up.

This is why I keep saying to keep the front end of the exhaust system and resonator, the same. There is a lot of power produced by the standard system.

Without the resonate tuning, we would still be in the efficency zone of a pushrod V8. Look at the VE that two stroke engines have achived, to produce 80+ HP from 250cc. only possible with the effect, of the sound wave pressures, that resonate systems can produce.

To site another 500cc cylinder, of the same make-up as ours. The Ducati 996 uses lifts of 9mm inlet 8mm exhaust, produces torque at 8000, HP at 8500. The Sport Production version increases the inlet lift to 10mm, the torque moves to 7000 and the HP at 9500. The torque is produced at a lower rpm, but it maintains the VE over a wider rpm range, to produce the HP at the higher rpms.

This shows the way increasing the lift will raise the max. torque and spread the curve. So there is no risk that increasing the lift will increase the VE of our engine.

Harvey.

[oab_au]

Originally posted by drivemusicnow
What about making it an interference engine...

increase the intake lift to 8mm... 9mmif possible AND increase the compression ratio to 11, maybe 12:1... yeah, you'd be screwed if you broke the timing belt, but would the higher compression ratio be enough to bump out power output "significantly"?
Doming the pistons would obviously give you even less clearence... but how would that affect overall torque output

Increasing the compression ratio number would give more problems than we need. The ratio is just a number, the main function is to increase the pressure in the cylinder, this will cause a higher tendency to detonate on its own, without adding to it by increasing the ratio.

I would prefer the lower 10:1 that gives a bit of leway if it suffers a lean mixture or advance problems, without self destructing.

Harvey.

[oab_au]

Originally posted by Chiketkd

Harvey,

Like Mychailo, I'm also interested in knowing the approx gains in hp & tq that might be returned if inlet lift was increased from 7mm to 9mm?

Having two cams ground instead of four would definitely save big $$$ as most shops in my area charge at least $100 per cam...

-Chike

Gid'ay Chike, I am not a numbers man. I read people saying things like " i'll put an under drive pully on that will give 4HP, the drop in filter will give 3 more and the coloured hoses will free up 6 more".

All I can say is you won't need a G-tec to show the increase. It will be most obvious.

Harvey.

Originally posted by THAWA


you realize that an auto is not slower than a manual right?

that acutally depends on what you are talking about there T

[Chiketkd]

Originally posted by oab_au
Gid'ay Chike, I am not a numbers man. I read people saying things like " i'll put an under drive pully on that will give 4HP, the drop in filter will give 3 more and the coloured hoses will free up 6 more".

All I can say is you won't need a G-tec to show the increase. It will be most obvious.

Harvey.

Makes a lot of sense Harv. If doing this will increases torque across the rev band then I'll be looking into having it done. Would be a worthwhile mod after upgrading my ECU, exhaust, and adding phenolic spacers...

Will also need to toss in some suspension and braking mods as well.

-Chike

[mbtoloczko]

Originally posted by oab_au


To site another 500cc cylinder, of the same make-up as ours. The Ducati 996 uses lifts of 9mm inlet 8mm exhaust, produces torque at 8000, HP at 8500. The Sport Production version increases the inlet lift to 10mm, the torque moves to 7000 and the HP at 9500. The torque is produced at a lower rpm, but it maintains the VE over a wider rpm range, to produce the HP at the higher rpms.

Nice example.