venetox

Thought my incoming build will interest some peeps here, and figure it's about time I start compiling some information on my current build and future plans.

I also hope to get some feedback (incoming "y no 1.8") from all of you on anything you think I am planning on doing that is egregiously wrong.


Yes that you read that right, a sequentially shifted, compound turbo VVT 1.6 with NOS, I won't go 1.8, I like making things harder for myself, it's part of the fun for me, this is why I'm retaining at least P/S and probably A/C too.
NOS is dependent on turbo sizing requirements.

Current setup is a pretty basic GT2554R running somewhere in the vicinity of 200 with a slightly crap DIY log-manifold, 5 speed gearbox, coil-overs and 1.6 VLSD.
Did the turbo conversion in about 5 12 hour days over last Christmas, then the car spent many many months getting painted, and now it's been sitting under a cover for winter (leaky top + **** weather).
The car is in a good state now, yes I will probably blow my diff soon, a torsen is on the cards currently, they don't pop up very often here.
I'll get some photos collated and uploaded over the next week or two once it passes certification.

ECU:
I run a Speeduino ECU, I like open-source things, it isn't perfect but I want some specific behavior for launch control, and flatshift, I will be modifying the code for these functions to suit my purposes.
Same goes for Sequential Shift-Cut and dual EBC control for the compound turbo setup.
This will mean running a second map sensor, I may instead just go for electronic control on only the secondary turbo.

Now to the fun stuff.
See, my mind regularly wanders and I find my self getting more financially draining ideas, I now think I may have a sickness as I have begun planning out the Compound Turbo setup.
I hope to have this ready around late next year, my current "I WANT" number is 600HP, I don't see this being impossible.
I will probably eventually want more.

This is very much in the planning phase so specifics will change, in saying that, there is only a very very very small chance that I do not go ahead with pretty much the title, I have dangerous levels of determination for this stuff.
My near term intention is to get a second running 1.6 in good health (probably from a NB 1.6 as we have plenty of those here in NZ and I prefer the true crank trigger as opposed to CAS), get it on the stand and start disassembling.
Get the ZL-VE head and mock things up, prepare everything for machining and assemble the block empty.
Then get it on a stand and start mocking up manifolds, turbo placement, etc.

My current thoughts and issues I can think of:

• Assuming this all works - Traction.. Boost by gear will help, but I doubt I'll be putting a whole lot down until 3rd.
• I will need to do some math on exactly which turbo's I will be use, current plan is to run something quite small like a GT2560R as the primary turbo, and something a fair bit larger in the GT30 sizing for the secondary turbo.
• Head gasket sealing will likely be an issue, as with the compound effect I will be running very high boost.
• I have settled on running a modified Mazda ZL-VE head for the VVT because the ports are quite a bit bigger, VVT is fun and they seem to flow better.
• Plan is mild porting and will have the cams reground by Kelford Cams, will need to decide on turbo sizing and some other parameters before I decide how aggressive to go.
• Intake and Exhaust manifolds are not an issue, I will fab the exhaust manifold, still deciding whether to go even deeper and go for ITB's with a pre-TB plenum chamber for feeding the boost into (Similar to what Garage4AGE has done here locally with his ITB Turbo Toyota Hilux with a 4AGE).
• Currently torn between the Quiafe QBE60G and QBE69G, both can be made to mate direct to the B6 block, will require fabrication of an adapter to mount the PPF to, currently I intend on retaining this for the purposes of making life slightly easier.
  The QBE60G is only officially rated to 375HP, haven't seen any specific torque ratings but I expect the HP rating is for heat management in racing, anecdotal evidence points to them being fine well into 600HP.
  The GBE69G on the other hand is "proven at over 1200hp" so plenty more than I will ever be touching.
  I will be running helical cut gears as this is primarily a street car and I want it to feel somewhat streetable, love the noise of straight cut, not on the way to work though, hence the compound turbo setup (want it to have a streetable rev-range).
  Thought about a BMW swap, but finding the gearboxes locally here is quite expensive, and they aren't that common here, also I really just want a sequential
• Possibly (probably?) I will need to go something bigger than the GT2560R, in this case I will also be running nitrous to lower the boost threshold and decrease lag. This would be active as little as possible because that stuff is expensive over here.
• Building the engine; I don't see any issues, have had great success speccing and building my mates 1.6 for around ~350hp, 600 is MUCH more but with good rods, pistons, billet main caps, ARP main/head stud kit, boundary oil pump, and an upgraded damper I think the bottom end should be good for it.
• Fitting two turbos in that engine bay.
  • I don't actually think this will be an issue, currently my P/S and A/C pump/comp are VERY much in the way.
    I intend on removing the P/S pump and replacing with an MR2 Spyder Electrically Driven Hydraulic PS Pump, I'm also intending on doing something similar for the A/C.
    I have found a number of Electric A/C units and will probably end up taking most of the A/C hardware from an NB.
    Utilizing my eye-crometers I think I can pretty well fit both, with the primary turbo quite forward in the engine bay on an angle, and the secondary turbo further back, to the side and sideways, downpipe could be a bit of a mission.
• Boost control; This shouldn't be a huge issue, at first glance it seems quite complicated but it should be just a matter of a dual port external wastegate on the primary turbo and a similar setup on the internal gate of the secondary turbo.
  From there I should be able to run two boost solenoids one for each and tune them separately.
  Not currently supported in my ECU, will be writing code for this.

Some questions I've got:
1. I hate being spoonfed, but I'm struggling to find consistent information about damper options for a 1.6, can't get a clear answer on whether there is an ATI SuperDamper option for 1.6 engines or if it is only for later model 1.6 etc.
If anyone has some info on that, I would greatly appreciated it.

2. What blindingly obvious mistakes do you all think I'm making.

3. Do you love or hate this idea, or somewhere in-between?

/this is pretty badly formatted, I will fix it eventually.

Ted75zcar

iTrader: (2)

Ditch the VVT, it isn't worth it.
turbo compressors are rated by air-mass and pressure ratio
Look into pat's various threads for clues on challenges associated with a too-small turbo stage in a compound setup
Godlesscommie runs a compound turbo with success I believe
Compound isn't the secret to high hp, for that you want a large single turbo, see Derek's build

venetox

Thanks for the input, will check out Godlesscommies and pat's thread, sure I've seen a couple but that was before I wanted to do it so didn't soak much up, you're definitely right on the VVT, it's more of a want to for the sake of it rather than for a meaningful gain.
Going compound mostly so I can have a wider power band with the small turbo, although I love my mates big turbo build I'm not a fan of the high boost threshold.

Ted75zcar

iTrader: (2)

Issue is that both compressors and both hotsides need to flow the peak hp airmass in a compound setup. You can do a twin or compound twin hybrid and bypass a limiting compressor in certain operating conditions, but complexity goes up quick when you do this.

A T25/28 IWG for example will not bypass 600hp worth of exhaust gas. You will certainly need to have an external wastegate there.

A 400hp compressor will choke at 600hp, it simply can't move that much airmass.

venetox

Hotside flow shouldn't be an issue as I'll be running an external gate on the small turbo, going to try internal gate on the big turbo.

Still need to figure out how the whole corrected airflow stuff works on compressor maps when feeding higher than atmosphere air into it, since in theory that should result in higher mass of air for same CFM.
That is my main concern though since I really don't know yet how big my primary will need to be to not choke whilst still not spooling like crap.
It very may well be that I end up having to substantially lower my end goal power wise, but I enjoy the process so we shall see.

Ted75zcar

iTrader: (2)

That is just it, for turbo compressors it is mass not CFM. A PD supercharger on the other hand is volumetric so it is CFM not mass. If I squeeze 1 lb of air into half the volume I get a PR of 2 and a CFM of 0.5x, but the mass is the same.

600hp of air has a given mass, let's say 60lbs/min for simplicity. It doesn't matter if that is at an absolute PR of 4 with a relative PR of 2, the mass is what matters. Off the cuff, I suspect the smallest compressor you could use in something like this for either stage would be a gt3076 or similar. Run 2 sequential 3076s at a PR of 2.25 each stage, and you get a a total PR of ~5, but they both must compress the same air mass, or 60lbs per minute.

Also keep in mind that hotsides act in much the same way, the PRs compound across each stage.

venetox

My understanding was that the compressor map is in corrected airflow at least for garrett and I believe at atmospheric pressure and like 25 deg c. Which is where they get the mass from, so by increasing the inlet pressure you are going to end up with higher mass flow at the same point in the map. Have to also take into account the increased temp at inlet also.

Or am I missunderstanding here?

Ted75zcar

iTrader: (2)

Yeah, I think you are misunderstanding a bit, but it is also possible the misunderstanding is on my side. Compound turbo is super common for diesel, maybe there are some resources available there that will provide clarity.

Edit: just looked at a couple of diesel oriented pages and it would appear as if you can get a higher air mass through a compressor in a compound configuration, so who knows?