Project Thread Supercharged Supra

[cribbj]

I think torque when it's laid down in a run like SW's is one thing, but as Scott is saying, balls of torque at launch, coupled with grippy tires and no wheelspin, is liable to break something.

Andrew, was SW driving his black car, or Chris' silver Supra?

 

[turboandrew]

It's his black car. FWIW, they are running 8.5 second 1/4 mile times (actually same car) as well. I guess if you get below 8.5 second 1/4 miles times, maybe then you need to worry Seriously, I think the way the drivetrain is set up in the Supra helps a lot. You have a very large rubber isolator from the driveshaft to the rear diff, which IMO absorbs a lot of shock.

 

[scotturnot]

It's his black car. FWIW, they are running 8.5 second 1/4 mile times (actually same car) as well. I guess if you get below 8.5 second 1/4 miles times, maybe then you need to worry Seriously, I think the way the drivetrain is set up in the Supra helps a lot. You have a very large rubber isolator from the driveshaft to the rear diff, which IMO absorbs a lot of shock.

I hope you are right, I am running the stock Supra 6 speed isolator and actually swapped the full 6 speed subframe assembly in. I guess time will tell.

 

[cribbj]

So I've been kicking around the idea of twincharging this motor. I'm also thinking of taking a somewhat different approach to it, and am open to your comments and suggestions.

Here's my idea: I'd have twin turbos with a FMIC, and they would blow into my existing twinscrew supercharger. The turbos would be sized with big A/R ratios, so they wouldn't produce any real boost below, say 3500 rpm. At low rpm, I'd be boosting solely with the supercharger, and when the turbos came on boost, I'd gradually open the supercharger's bypass valve to unload it, and let the turbos take over. At that point the turbo's would be blowing through the supercharger, and through the open bypass valve, and the supercharger would simply be freewheeling.

This would have the added benefit of reducing the supercharger's parasitic load at the top end, which should add an additional 60-80 HP to the flywheel.

So although on the surface, it would look like a two stage system, in reality it would only be a single stage of compression, with two different forced induction systems working in their happiest regions.

I don't need or want the crazy boost pressures that two stages of compression would produce, but I do think this system might be able to combine the strengths of both technologies.

The trick, I think, would be keeping the boost pressure under control, while the turbos are coming up, because they wouldn't be pressurising the engine directly, but would be pressurising the intake of the supercharger, and it, in turn would be adding its contribution and compound pressurising the engine. With judicious control of the SC bypass valve, hopefully it could be a smooth process.

Comments?

 

[mshawari1]

Nice idea John,

But how you will control the opening of the valve. Could you program the ECU to actuate after 3500 RPM?

I was thinking about boost control via that bypass valve .

 

[cribbj]

Mosab, I have a dual port actuator on the supercharger bypass valve, and the 2nd port opens the valve under positive pressure. So, (in theory anyway), it should be fairly straightforward to set it up to control boost, or in this case, to load/unload the supercharger.

I run a standalone EMS from AEM, and it already has a built-in boost control function. If that didn't work out, I'd probably have to pick up a cheap little two loop PID controller and set it up for cascade control in order to control both the wastegates on the turbos as well as the bypass valve on the supercharger.

 

[spf_lexus]

Nice idea Cribbj, whats the biggest I.D available for BPV? 50mm? What about the possibility of using 2 valves with half pressure duty for each? Might take the strain off the single valve.

 

[turboandrew]

Sounds nice, but if you are wanting to stay under 600 rwhp, wouldn't the supercharger be capable of this alone? I am not sure what your HP goals are...

Also don't forget, you'll be adding another 70 lbs or so in turbo stuff.

 

[Vander]

I saw a Nissan 350z or Infiniti G35 in a magazine with a supercharger, turbocharger, and nitrous. I would try and look it up on the internet and see how they did it.

 

[JustenGT8]

So I've been kicking around the idea of twincharging this motor. I'm also thinking of taking a somewhat different approach to it, and am open to your comments and suggestions.

Here's my idea: I'd have twin turbos with a FMIC, and they would blow into my existing twinscrew supercharger. The turbos would be sized with big A/R ratios, so they wouldn't produce any real boost below, say 3500 rpm. At low rpm, I'd be boosting solely with the supercharger, and when the turbos came on boost, I'd gradually open the supercharger's bypass valve to unload it, and let the turbos take over. At that point the turbo's would be blowing through the supercharger, and through the open bypass valve, and the supercharger would simply be freewheeling.

This would have the added benefit of reducing the supercharger's parasitic load at the top end, which should add an additional 60-80 HP to the flywheel.

So although on the surface, it would look like a two stage system, in reality it would only be a single stage of compression, with two different forced induction systems working in their happiest regions.

I don't need or want the crazy boost pressures that two stages of compression would produce, but I do think this system might be able to combine the strengths of both technologies.

The trick, I think, would be keeping the boost pressure under control, while the turbos are coming up, because they wouldn't be pressurising the engine directly, but would be pressurising the intake of the supercharger, and it, in turn would be adding its contribution and compound pressurising the engine. With judicious control of the SC bypass valve, hopefully it could be a smooth process.

Comments?

You'd need a big bypass valve John!!

What you have described is how my setup worked and with a 40mm BOV it basically made no difference to the compund boosting that i could measure.

You have the setup to take the higher boost though so i wouldn't worry too much. Biggest issue is heat controil post SC and your post SC water/meth setup appears to do a good job there.

I'm still keen to give the twin charge a crack again with the bigger M112 to get my top end back....the car was an absolute weapon to drive and with such a predictable boost curve you could balance it on the throttle all day I just need the 'built' internals.

You've seen this vid right?

http://au.youtube.com/watch?v=zczgKbYK9CE

That's all steering on the throttle

Advantages are many and apart from weight and high boost, no downsides really.

 

[cribbj]

Thanks everyone; the additional weight is a concern, but not a big one. What's more of a concern to me is the spaghetti mess of piping that goes along with a twin turbo installation, and the resulting lack of access to the rest of the engine.

Interesting comment on the bypass valve, Justen; I recall during my gas compression days that we could effectively unload a stage of compression with a bypass valve that was 1/4 to 1/3 the size of the suction valve. Maybe that only works for gas compressors, though. I suppose there's nothing stopping someone from putting in a couple of bypass valves in parallel as spf_lexus said.

Vander, I think turboing and supercharging will be exciting enough for me; I'll leave the nitrous to the certifiable crazies ;-) I'll have a look for the article, though 'cause I'm curious how they did their piping.

 

[JustenGT8]

I looked back thru some of my notes and i think why i was still getting high compound boosting was the fact that my smallish valve probably wasn't opening much on turbo boost anyways.

A good sized wastegate, say a Turbosmart 60mm dualport should do the job nicely.

You would run it post Tb on vac to act as a normal bypass for cruise. For boost you would make to make sure your turbos are well spooled before opening the valve again or you will either create horible boost holes or send the system into surge.

You could do this with a simple solenoide valve controlled by a hobb switch or get a bit fancier with one of the EBCs available...the latter gives the option to set a target boost level that it will try and hold so probably a better way to go.

Plumbing is not that hard you sook I would go a big single anyways as it's turbo top end you want and lag isn't an issue. The big single compressor will also be more efficient and flow more air per pressure ratio increase (boost)....this will minimise any residual compound boost effect.

If i go this route i will go twins but only because i have a coupla big T70s sitting there ready to go and my setup is already well configured for twins.

 

[Cobber]

How much is too much? When you need to brake for the next corner while still laying down rubber?

A 100 shot of no2 would be all that I would do with your supercharger set up John, easy to install and push to pass capabilities.
Just my 2 cents, I like to keep things simple.

 

[JustenGT8]

How much is too much?

The eternal question eh

Sometimes i do things just because i can or even to see if i can....why else would someone put a TT RWD V8 in a transverse 4 cyl AWD???

I think with John's twinscrew being so efficient that you are right Cobber and a NOS shot would be more than enough for the occasional times you needed that little extra The twincharge with the M90 was so much fun that it is tempting to try an do it properly with the M112 and big turbos....if it was an SC400 or Celsior i would do it in an instant. For the track focused GT8 i'm not sure sure as it is pointless for track work...it would make it more a drag/hoon car.

Still, if John is gonna do it we all may as well help him do it right

 

[cribbj]

I hear you Andy, but I've been infatuated with twincharging for years. It's like the call of the siren that's luring me onto the rocks...... So thanks matey's for helping me onto the rocks ;-)

Hmmph Justen, big singles are for inlines, a V motor needs a set of twins. At least that's the way we always did the big yellow motors from Peoria ;-)

Here's a link to that project Vander was on about: http://www.turbomagazine.com/features/0701_turp_nissan_350z_twin_charged/index.html. As usual, light on technical detail, and heavy on advertising, but they're using an electric clutch to cut out the supercharger at higher RPM. They also say in the article that they were too worried about the stock motor's innards to activate the nitrous!

 

[Cobber]

Ok, because you can... as good a reason as any I guess. Without inovation we would all be driving model T's I guess, and wouldn't that be fun.

Lets see what will work out on paper first, it's cheaper than reverse engineering it.

displacment 4lt
cam lift & timing?
Supercharger 2.3 whipple? 15 psi? on non intercooled Richwood manifold
Water / Meth post supercharger
Fuel, high octane service station pump fuel?
charge cooling delta T (this I think is the biggest issue)?

Anyone any good on desktop dyno?

I agree boost control is now very acurate a number of different ways, so I wouldn't worry about that too much just yet but remember waste compressed air is a waste of energy.

 

[stevechumo]

If you want more power, then adding a single turbo is all you need. It'll save you time and the hassle of adding a twin system. Perhaps a GT40R and your current twin screw are just perfect. You know, just get it rolling and see how the complete setup behaves on the streets and maybe tracks. 600 rwhp with no lag is so easy with this setup. I once thought about quad-turbocharging my SC, but I ditched the idea due to its complication, although it's very doable.

 

[Lextreme II]

You guys are out of control... LOL..

 

[XR8tt]

Gt35/40 , T04Z, Master Power T70, Borge Warner S374, would work fine ..Almost any 650 to 800 h.p turbo..
Runing twins is not that much more fab work. After all you still have to run a cross over pipe on V engines or mount turbo in the centre if room permits...
I'm using two Precision t3/4 hybrids on a Ford V8. One thing with smaller turbo's is they have internal wastegates which fit in tight engine bays.. With two wastegates there is no issues with boost control..

 

[turboandrew]

FWIW, my current plan calls for 2 x GT2871R turbos, each good for a little under 400 rwhp. As far as I can tell, these are very very similar to the HKS GT2835R turbos I had on the 2JZGTE. I was able to hit 17 psi at 4200 rpm with the 2JZGTE, so I am hoping I can get that boost level at around 3200 rpm with the 1UZ.

With a supercharger, I would go a bit bigger, but my plans would also call for more HP.

Another option, since you do have 2 engines, is to build one supercharged, and the other turbocharged. Then you'd get to compare each on their own, and if you still feel having -two- engines, one super, one turbo, is not enough , then combine them...