James' Civic Rebuild Thread + High Power ER Motor Theory

[spangleking]

You sound like a design for technology student with solidworks.
It turns out some nice looking solutions.
I would not want my city to go faster too much.. it would be frightening... ( :
Sounds like a very rational cool project..

[3GCVC]

Hey that is amazing work on the ECU might need to get mine fixed lol.

what size turbo would you sugest for 150-170hp not quite as laggy as the t25 but bigger than stock?

[city_cabriolet]

I thought the Honda City Turbo was the first mass produced car to have 100% volumetric efficiency?

[James]

Im not sure about turbo, possibly a T2 as they were meant to be the smaller brother of the T25. Another idea might be those rodeo turbo's people are using as upgrades. The compressors are meant for diesels so they will be good for high boost. If we could find a compressor map for one I could tell you if it would be suitable.

Not sure about that city_cabriolet. Pretty much any turbo car has over 100% volumetric efficiency and there were plenty of turbo cars before the city.

[James]

Might have a bit of a solution for the lag that this larger turbo will generate. Will keep you informed of any developments

[James]

SC-14 Supercharger off a toyota 2 litre straight 6

[mangusta]

My dad fit a saab supercharger from a 2L onto a Toyota 18R (2L) engine and had nothing but trouble, usually on smaller engines you lose more than you gain as driving the supercharger not only takes load but slows you revving ability ...

That coupled with the fact it's off a 2L 6cyl engine means there is no way an ER with a redline of 6k rpm is going to flow enough - still will be awful fun finding out!

[city_cabriolet]

My mate has a old celica with the 2-litre 6 supercharged.

That engine comes either supercharged or twin turbo. Fantastic engines, his car's a weapon.

[James]

My dad fit a saab supercharger from a 2L onto a Toyota 18R (2L) engine and had nothing but trouble, usually on smaller engines you lose more than you gain as driving the supercharger not only takes load but slows you revving ability ...

That coupled with the fact it's off a 2L 6cyl engine means there is no way an ER with a redline of 6k rpm is going to flow enough - still will be awful fun finding out!

Good, finally provoked some discussion

usually on smaller engines you lose more than you gain

The size of the engine doesn't really matter as long as the supercharger is setup correctly and is of a suitable size and type, they superchare model plane engines! A rootes type supercharger like the one above can take up to about 25% of the engines power to turn it, but will provide a boost of up to 50%, so it easily covers itself.

Have you ever driven a supercharged levin or mr2? they are onnly a couple hundred cc's bigger than the city motor and those things HAUL!! Its like there is a 2.4litre motor in there, and it goes pretty well to redline. I was led to believe the supercharger I was buying was off one of these, which are 1200cc but I found out its off the 1gz after I had bought it, however there is very little difference, about 25mm longer and 220cc more displacement. Its probably better for the reasonably high boosts I want to run as I can still turn it pretty slowly.

slows you revving ability

Interesting, I handn't considered that, I would have thought from the large increase in torque the boost provides that the negative effect of the additional rotating mass and drag would be overcome, guess Ill find that one out. Ill cover a bit more on this furthur down the page.

That coupled with the fact it's off a 2L 6cyl engine means there is no way an ER with a redline of 6k rpm is going to flow enough

Sorry but I dont agree with you there The size of a supercharger isn't quite like the size of a turbo. A rootes supercharger is just an air pump, its not even technically a compressor. The one I have pumps 1420cc's of air each full rotation. An ER engine at full throttle and peak torque wants about 600cc's of air each crank rotation, as there are two crank rotations for a complete 4-stroke cycle.

OK so if I gear the supercharger 1:1 with my crank, then I end up with 820cc's of extr air at full throttle each revolution. This air will stack up and create boost, my guess is about 13-15psi. Not earth shattering but it should be available from just off idle, say ~1500rpm. I will run an electromagnetic clutch on the supercharger drive pulley like the original toyota system, and have an air bypass valve. The supercharger will only be engaged when >60-70% throttle is applied, and the revs are above 1500rpm, and the engine is warm. Once the supercharger is running the bypass valve will control the boost post-supercharger to between 13 and 15psi by bleeding air back to its intake. The turbo will be feeding the supercharger and will start to produce boost hopefully around 2500-3000. This will take load off the supercharger and the bypass valve will open to keep boost to the set level. Once the bypass valve is completely open the supercharger is no longer doing any work, so the electromagnetic clutch will be disengaged and teh system will be running like any other turbo setup. I hope for this crossover to occur at about 4000rpm or slightly lower, going on boost figures davo gave when he had the same turbo as Im using installed. Once the crossover has occured, the boost will no longer be controlled by the bypass valve and instead will be controlled by the turbo wastegate. In the final incarnation this will allow the boost to rise to around 20-22psi to make max power high up in the rev's, but probably for street driving and traction ( ) this will just keep the boost at an even 15psi, so the torque will be extremely flat across the engine rev range, should just be like driving a 2.5 litre n/a car but sound cooler

Ah yeah the rotational intertia of the supercharger shouldn't be too significant as the rotors are quite light aluminium, and driving it at 1:1 is quite slow, the standard 4agze 1600cc drives it at 1.25:1 and apparently you can really notice the added drag when you increase this up to like 1.7.

As for mounting it, it is going to go where the air conditioning compressor goes on a stock city turbo. It just fits in my civic there and will be mounted in a similar fashion with brackets going back to the engine. The turbo will sit just behind it, keeping all the carge piping reasonably short. The path will go:

Intake --> turbo --> throttle body --> supercharger (with bypass valve in parallel) --> intercooler --> possibly another throttle body syncronised witht he first so the plenum isn't ridiculously large off boost, yet to be decided --> intake manifold

[turbocab]

faaaarrrrrrk
keep us posted

[city_cabriolet]

+1

[Smithy]

Will there be, or are you expecting, any problems modifying the ecu to run this set up ?

[3GCVC]

Ah the old Supercharged Turbo its a great idea hard to get working properly but you sound like you have it all in order i will be watching to see how this goes, i have been thinking about doing this for a while now.

[turbo trevor]

The Nissan March/Micra Superturbo also used the supercharger and turbo design.

[James]

faaaarrrrrrk
keep us posted

Will do

Will there be, or are you expecting, any problems modifying the ecu to run this set up ?

In short, nope. I think it might actually be easier to tune tahn a laggy turbo setup, as the boost will be pretty constant throught the rev range. I have a feeling it will probably run not too badly right off the bat, the T1 turbo is making decent boost by 2000rpm anyway.

Ah the old Supercharged Turbo its a great idea hard to get working properly but you sound like you have it all in order i will be watching to see how this goes, i have been thinking about doing this for a while now.

Yeah Im hoping I will succeed where others have failed with superior engineering. Something I have seen seriously lacking in DIY supercharger installs all over the net.

The Nissan March/Micra Superturbo also used the supercharger and turbo design.

Thanks for that reminder, did a lot of research on these little engines today, turns out they have the same bore as the city turbo! Be interesting if they run a factory forged piston, although they might not be much easier than city turbo parts to get hold of.

Here is a picture of the march system, identical to how I was planning on doing it so thats good.



The only thing that is going to require much thought is what is going to actuate the bypass butterfly and how to control it. Should be too challenging tho.