GE intake manifold on GZE

[KReynolds]

There is a clearance problem involved with putting a NA manifold onto the GZE correct? I think it involves the SC interfering with the manifold. I think I am going to try it since I have the motor on the stand. Think it will make a noticible difference?

[Boostman]

If you put the GE intake mani on wont you be getting rid of the SC?

[KReynolds]

No. I really haven't researched this all out but I have a GE intake and a GZE on the stand I'm about to start building so I'm going to try and see if it can fit with out ridiculous mods. But no I'll still be keeping the SC.

[Boostman]

Well how is the SC mounted to the intake? Isn't is mounted to the whole intake manifold? If so then I wouldn't think you could use the GE manifold on a GZE because there would be no way to mount the SC on.

Kyle

[tgidavid]

The issue is that the intake manifold is that it will hit the engine lid latch. The latch is held by 3 bolts. You can actually cut off the bottom part of the bracket and make it work.

[supermr2]

I have a GZE intake manifold if you need one. I pretty sure you are doing this as the GZE one has the natsy dogleg and the NA one does not but just thought I would offer it up for you...

[feral4mr2]

you have to lower the s/c approx 3" for it to clear the ge inlet manifolds runners. this involves either a cutom made braket or serious midification to the original one.
then if your going to have the TB after the s/c like on a turbo car, you need a hi flow BOV to vent the 1.2 liters per revolution the s/c produces. or you might be able to plumb it so the TB is still before the s/c (save a lot of headaches IMO) and have the i/c plumbed directly into the ge inlet manifold. the longer runners should allow for some decent torque.

[edmcguirk]

Longer runners should not matter with a SC. As a matter of fact shorter runners should work better because the air comes from the SC in pulses. The magnitude of the pulses are determined by the volume of the blower in relation to the volume of the intake manifold. Therefore a bigger manifold will have smaller pulses.

Those pulses don't really matter that much at higher RPM but at lower RPM they force the engine to breathe when the cams are not really into their efficient zone yet.

However if your cams have a large overlap (they shouldn't) it will make the blow through during overlap much worse. Just one more reason why SC engines like small overlap cams.

In my opinion, the differences between the two intake manifolds has a much bigger effect on fuel distribution than air flow.

[ToyotaTechGeek]

how will the differences be more of a fuel distribution thing? i'm curious. i also disagree partially about the 'pulses' because unless the IC is completely eliminated, then i don't see how the intake charge is 'seen' as pulsed at the manifold.

[edmcguirk]

I may have jumped the gun on fuel distribution differences. I don't remember exactly but I think the injectors are right at the intake ports. I was mistakenly thinking that fuel in the intake airstream wouldn't turn corners as well as the air can. However I think the differences in air distribution between the two manifolds would be subtle at best on a SC engine.

The SC on the other hand does produce pulses. All roots type blowers do. The lobes simply do not pass the same amount of air during each degree of rotation. Three lobe and twisted lobe rotors were created to try to cure that and several other problems inherent in the two lobed rotors.

A 1 liter pulse in a 1 liter intake manifold would almost double the pressure but a 1 liter pulse in a 10 liter intake manifold would be one tenth the size. Also if you raise the pressure from 1 BAR to 2 BAR you cut the size of the pulses in half. The SC is putting out air in pulses and the engine is taking in air in pulses and those pulses are not even remotely synchronized.

The whole point is that if the air does not move into the combustion chamber by itself, the air pressure in the intake manifold starts to rise beyond the average boost level. That is one reason you will see that the torque curve on the SC engine is broader than the the torque curve on the NA engine. The SC can breathe over a broader range than the cam lobes. The SC does not act like a NA engine running in a room that just happens to be 8 PSI over sea level air pressure.

I am not saying that long intake runners would hurt HP, I am just saying that they have less advantage on an SC engine and there are even advantages to using short runners with an SC engine.

Another example is that many tuners drop variable valve systems when they supercharge an engine. It's just not necessary with a positive displacement type blower. The torque curve gets so wide that it becomes necessary to favor the higher RPMs because low end torque is no good if you never need to run the engine that slowly (when you want to drive fast you never run the engine below 3000 RPM).

Very few of the people who run big pulleys know how low the torque curve wants to go. The stock ECU has a lean spot below 3500 when you run extra boost and many dyno runs don't bother to run below 3000 anyway.

[ToyotaTechGeek]

well, i have proven that not only does the larger pulley make the lean spot, a very efficient intercooler does the same thing (without the monster-sized pullies). as for pulses, yes, they (positive displacement sc) pulse, but at the point of entry into the manifold, those pulses have gone through outlet piping, through the intercooler and then through another pipe and then down into the manifold. i'd venture to say that the pulses have been 'dampened' by then. isn't that why a boost gauge does not pulse as it reads manifold pressure?

[ToyotaTechGeek]

also, the sc12 clutch engages @ 2500rpms and the 4AGZ-E revs to 3000 rpms in a half a nanosecond...what difference in the torque curve would really be experienced? (i'm asking a serious question...i would be interested in knowing what the difference would be in your opinion). i mean, sure, at a low-speed event, staying in 2nd gear and utilizing every squeezed ounce of torque is great and all, but it's nothing a bit of toe-heel technique can't cure (to keep the sc engaged).

[feral4mr2]

engages at 2500rpm???
the factory ecu triggers the s/c clutch at -8 vaccum.

[ToyotaTechGeek]

i guess i need to have to operate the dyno myself this next round of dyno pulls/tuning so that i can graph whatever torque in whatever rpm range. i guess i also have been looking at the s/c light which is on @ 2500rpms...or so it seems...


o/t what's up, john? long time! i have a bunch of projects i want to discuss with you!

[edmcguirk]

I think it depends on the gauge. I do not have a permanently mounted boost gauge. I attach a 4 inch manifold vacuum gauge when I want to check boost and the needle does vibrate quite a bit at times. (most dash mounted boost gauges are heavily damped)

A good boost guage shows that boost is on at any RPM as long as your foot is on the gas. The SC does leak a little and it doesn't make full boost until it has a few RPM under it's belt. If you have a bigger pully, full boost will show at a lower RPM. My current car is stock and it doesn't get full boost until about 3000 RPM. My previous car had a big pulley and I think it had full boost at almost 2000 RPM. (I hope my current SC is not leaking too much)

As far as "experiencing" torque, you are exactly right. You are not going to see differences in low end torque unless you can find a nice steep hill that pretty much balances your available torque.

However the torque is definately not there when using the stock ECU. I have seen dozens of dyno plots posted over the years and there is quite a jagged drop in the torque curve at lower RPMs on almost every one. At the same time I have seen dozens of dyno plots that show a nice smooth curve going all the way down to the bottom of the plot for stock boost engines.

Only some of the better tuners have more than stock boost and also a smooth torque curve all the way to the bottom.

That lost torque at low RPM does not matter on the track because you never use the low RPMs unless you are in the completely wrong gear. On the track you should never see RPM below 4000. On the other hand that lost torque does make a nice difference in around town driving and I think most of the guys who installed the Grunt Box know exactly what i am talking about.

[ToyotaTechGeek]

Originally Posted by edmcguirk

That lost torque at low RPM does not matter on the track because you never use the low RPMs unless you are in the completely wrong gear. On the track you should never see RPM below 4000. On the other hand that lost torque does make a nice difference in around town driving and I think most of the guys who installed the Grunt Box know exactly what i am talking about.

i sorta disagree with this statement. i do so because in a tight course (autocross) why would one shift down into 1st gear if the majority of the course is 2nd gear. so, going into a switchback (180*) why shift back into 1st? all it (downshifting to 1st) would ever net is wheelspin with or without race compound rubber.

[ToyotaTechGeek]

my last dyno chart.

[ToyotaTechGeek]

Originally Posted by edmcguirk

I think it depends on the gauge. I do not have a permanently mounted boost gauge. I attach a 4 inch manifold vacuum gauge when I want to check boost and the needle does vibrate quite a bit at times. (most dash mounted boost gauges are heavily damped)

A good boost guage shows that boost is on at any RPM as long as your foot is on the gas. The SC does leak a little and it doesn't make full boost until it has a few RPM under it's belt. If you have a bigger pully, full boost will show at a lower RPM. My current car is stock and it doesn't get full boost until about 3000 RPM. My previous car had a big pulley and I think it had full boost at almost 2000 RPM. (I hope my current SC is not leaking too much)

As far as "experiencing" torque, you are exactly right. You are not going to see differences in low end torque unless you can find a nice steep hill that pretty much balances your available torque.

However the torque is definately not there when using the stock ECU. I have seen dozens of dyno plots posted over the years and there is quite a jagged drop in the torque curve at lower RPMs on almost every one. At the same time I have seen dozens of dyno plots that show a nice smooth curve going all the way down to the bottom of the plot for stock boost engines.

Only some of the better tuners have more than stock boost and also a smooth torque curve all the way to the bottom.

That lost torque at low RPM does not matter on the track because you never use the low RPMs unless you are in the completely wrong gear. On the track you should never see RPM below 4000. On the other hand that lost torque does make a nice difference in around town driving and I think most of the guys who installed the Grunt Box know exactly what i am talking about.

my gauge doesn't bobble nor is it 'heavily damped' to my knowledge. in the next few months, i will be conducting a crapload of tests and hope to post my findings here. i am now especially interested to take a boost reading at the sc outlet now.

[edmcguirk]

Originally Posted by ToyotaTechGeek

my last dyno chart.

Actually, you have the graph squashed down so flat that it's hard to see anything. However unless you have changed your cam, the torque peak should not be 4500 RPM. That tends to indicate to me that you are losing some torque below that.

[feral4mr2]

the lil feral see's 14psi @ ~3200rpm.

The ECU engages the supercharger based on intake manifold vacuum. When the vacuum drops below 8" the supercharger clutch is engaged. The clutch stays on untill the intake manifold vacuum has risen to over 10" for a period of 5 seconds. This time delay was added to avoid cycling of the clutch during shifts and momentary throttle transitions.

from here:
http://www.mr2.com/TEXT/SuperChargerInfo.html

geek, yea i have heaps of still on going projects. just never seem to get around to starting or completeing any of them, plus the $$$ part. i have 3 aw11's and i like to work on all of them one way or another.