Miata scroll supercharger (homemade setup)
 

Hi everyone,

I'm Marc, 25 years old.

I came here to find some good informations to transform an atmo 1.6L 1991 miata to a supercharged version.

I started a rare project: install a VW G60 supercharger


My Car:

https://www.miataturbo.net/attachmen...5&d=1312989020


What the engine look likes:

https://www.miataturbo.net/attachmen...5&d=1317893113

I got 10.5 psi at 4500rpm but my manifold air temp reach more than 210°F (ambient 77°F).
I'm planning now to install a intercooler before engine failure...

What would be a good air temp target?

Haven't you already got a thread on this?

Ambient is a good target.....but as I said in your other thread 210DegF isn't that high in my experience, you can safely drive at those IAT's if your tuning is appropriate.

Fitting an IC isn't going to be a big deal on your setup anyway, as you blow through your throttle, no long intake tracts, so get to it and bask in the lovely cold(er) air.

I worried about one thing:

My MSPnP can't read over 210°F so I think it cannot adjust fuel very well.

What do you think?

(I recreate my thread here because it must be the best place ;) )

I think you can modify the code to 'shift' the reading higher (or just use DegC :P)

If you can afford the few hundred £$ an IC will cost you then you should do it. There's no downsides for your setup.

I'm already in Celcius :(

I will search in megasquirt if I can set up the limit temp of IAT.

Thanks

I'm on my way to install an intercooler.

The cardboard represent the future intercooler's core size.

https://www.miataturbo.net/attachmen...ine=1318840938


I have removed the OEM fan to put the pipe between radiator and anti sway bar.

http://i42.servimg.com/u/f42/16/62/88/03/2011-111.jpg

Very cool, but hot damn those are some high IATs

The IC will have dramatic effects.

You will need fans. Try routing hotside through fender.

I have two 10" fans and I'll try to put them between the IC and the radiator.

Pushers or pullers? Get some french ducting going asswell.

They are universal type. I can return the blades and switch polarity.

I'm planning right now (in my head) on fresh air feeding.
I will try to make a heatshield box for the air filter or, change the air filter (maybe a mushroom) and bring some air from the outside to it.

Cold air intake< ducted and and sealed IC and radiator.

Coming from the land of VW I can say that you picked the least reliable supercharger on Earth. However, it's nice to see the fab work on this.

Cold air intakes are worthless on a FI car. Unless your sucking sub 0 temp air the iat coming out the blower will be the same regardless. And if you are sucking air that cold you will cause problems in the blower.

I dont think I agree with that. The temperature at the outlet of the compressor is a product of the compressors efficiency and the inlet temperature.

Will a CAI make a big difference. No. But I think there should be a difference.

Small difference in temperature. Not enough to notice though. What full tilt said.

Not saying 100% sciences it will do nothing. Compared to ducting it will do nothing. Ducting will drop your iat astronomically compared to a cai.

While this is true, the temp at the end of the system (throttle body) will be proportionally cooler as the temp at the beginning of the system (filter) drops. Compressing the air increases the temp by a ratio of compressor efficiency and inlet temperature. Thus if inlet temp drops 30 degrees, then outlet temp drops 30 degrees.

But you see my dear Watson if your charger is 200* and your sucking 70* air verse 100* air the air coming out of the blower is going to be ~200* regardless of the air going in. Could be a little cooler but still hotter then a 30* difference between having a cai and no cai.

That 30 degrees absolutely DOES matter, because the intercooler works the same way as the compressor (given identical conditions), only cooling the air X total number of degrees, so if the compressor outlet temp is 30 degrees cooler, the intercooler outlet temp will be 30 degrees cooler.

This is assuming that the intercooler isn't over sized for the application and that the charge isn't approaching ambient temp already. If you're already approaching ambient IATs, obviously you're not going to see a drastic temp drop. I'm in no way saying that OP shouldn't duct his intercooler/ rad. Merely pointing out that it's foolish to say that drawing cooler air doesn't have an effect on IATs.

^^lmao!!!

Colder air before the supercharger will have a direct effect on the air coming out. This is for a turbo but it's pretty much the same deal.
Tout = (Tin + Tin x [-1+(Pout/Pin)0.263]) / efficiency


Tin: temperature before compressor (In Rankin)
Tout: temprature coming out of the compressor (in Rankin)
Pin: pressure in (asbolute, in psi. ~14.7 psi)
Pout: pressure out (absolute, in psi. ~14.7+boost, ~25.2 in this case)
efficiency: I don't know the % for these, say 0.6

For my turbo setup, at 10C in, out at 54.5C. At 40C in, out at 89.3C. So delta in, 30. Delta out 34.8C. The lower the efficiency, the higher the "out" delta becomes.

So cool air intake doesn't matter, or does it ?

It does not because like everything on the internet you missed the point of the discussion. Ducted fmic > fmic > ---- rape in prison > cai

I never did say ducting is not important, it is.

The point is that you cannot, in any point of view, say that cai doesn't matter, because it does.

If you think I took that stuff out of some creepy internet website, I'm a mechanical engineer and design vehicles for a living. :)

Ambient temps of 77 and IAT of 210. Lets assume the temps at compressor inlet were elevated quite a bit by being drawn from inside the bay, like perhaps 100 degrees?
10.5 psi of boost
77 F = 298 K
100 F = 305 K
210 F = 372 K

((25.2psi / 14.7psi)^0.2857)-1
__________________________ = 84.9%
(372K / 311K)-1

((25.2psi / 14.7psi)^0.2857)-1
__________________________ = 84.9%
(xK / 298K)-1

x=356.435

So if you were to get the compressor inlet temp down to ambient (77F or 298K) you would be rewarded by having the compressor outlet temps drop to 356K, or 181 degrees Fahrenheit.
Thats a 29 degree drop in temp at the outlet from a 23 degree drop in temp at the inlet

This is you dancing around the subject. Processed carbohydrate helms or no, cooler intake charge is better than hotter intake charge, and the temperature when it enters the compressor absolutely has an effect on temperature when it leaves it.

Thanks guys for debating :)

Form my point:

-CAI is not enough efficient to drop down the air temp entering in the engine. That's why IC must be installed.

But,
-feed the supercharger with fresh air (high O2 concentration)will give you hot air with high O2 concentration at the oulet and give you a better efficient supercharger.

Actually, my air filter takes underhood air (so, more than ambient, maybe more than 100°F) :(

IC + CAI, is the dream team to give a good gain of horsepower.
I will need bigger injectors to follow the gain of O2 entering in combustion chamber.
I planning on 600cc running E85, sounds good?

New radiator, new fan
https://www.miataturbo.net/attachmen...ine=1320221649

Piping supercharger side finished (except clamps)
https://www.miataturbo.net/attachmen...ine=1320221649

https://www.miataturbo.net/attachmen...ine=1320221649

New intercooler
https://www.miataturbo.net/attachmen...ine=1320221649

Work in progress...

The new setup looks good. Just don't forget the sealed ducting as has been previously mentioned, which ought to begin inside the bumper cover mouth and extend to the radiator to be effective.

As for E85, yes, 600cc injectors ought to be enough to handle it with your setup. However, I have no idea how much airflow that supercharger can produce (and can't find it in a quick search), so what you need to do is some math related to actual airflow you are measuring vs fuel needed to support it. Here is a handy rule-of-thumb list that can help you see some injector sizes and what they can theoretically support in terms of airflow in lb/min. Do keep in mind that when you use E85, you'll also need to increase your fuel pump capacity by up to 30% just to maintain current power levels without running too lean.

Last part of the piping on intake's side

https://www.miataturbo.net/attachmen...ine=1321343456

https://www.miataturbo.net/attachmen...ine=1321343456

https://www.miataturbo.net/attachmen...ine=1321343456

https://www.miataturbo.net/attachmen...ine=1321343456

I would move that IAT sensor, many people have heat soak problems in that area behind the radiator. I would suggest putting it on that U looking piece after the IC(first picture of "the last of the IC piping")

Thanks for the advice.

I'm afraid that the U piece is too exposed to water on wet road. But I will think about something to resolve this threat.

What's the little heat exchanger adjacent to the IAT?

It's a oil radiator from a renault r5 turbo2 :)

Update:

Intercooler tighted up, clamps on, BOV connected, IAT wire lengthen.

https://www.miataturbo.net/attachmen...ine=1322467731

Still to do: Wiring for radiator fan and refill of engine coolant.

Hi everyone,

I have goal in sight :

Last things are done, I think I'm gonna stay with this setup.

https://www.miataturbo.net/attachmen...ine=1323798871



I have a ride last sunday. Results of the FMIC was there!

In full throttle from 3500rpm to 4500rpm:
Manifold air temp was 64°F (Unfortunatly, I didn't remember the outside air temp)
Boost was at a constant 8 psi

I'm pretty satisfied of the results.

I'm gonna rebuild my B6 this winter and then I will go further in rpm.

G supercharger check done.

Everythings seems fine.

I have used the same oil feed than B6 turbo engine. the pressure didn't blow out internal gasket of the G

https://www.miataturbo.net/attachmen...ine=1324475606

https://www.miataturbo.net/attachmen...ine=1324475606

Yeah I read the first post and this was my immediate thought...

Any power figures yet?

Not yet...
I will make a dyno run in spring time. Then we will can compare to roots and rotrex 's boost, Hp and torque curves.

my boost is not reaching more than 8psi because I must have a leak in my new piping setup. I will fix this later.

I've started my engine rebuild during this winter.

Seeing less boost, is normal when you add an intercooler(with a SC). When the air cools the density goes up, and the pressure goes down. Check your datalogs for injector pulse width. If your pulse widths have stayed the same, or increased, without a change in AFR, then you don't have a leak.

With all those couplers I would still do a leak test. I have piping routed almost the same with a ton of couplers and I was leaking a tiny tiny bit and never knew it until I did a boost leak test.

Yes, before IC installed, I was running 10psi at 5000rpm. Now I've got 8psi. I'm aware about air pressure loss. But I've check my piping after a drive and I find "condensation" on some edges of couplers.

After looking at some photos... you need to invest in t-bolt clamps. The worm drive clamps are useless.

Well, I bought some T clamps.

But at the intake manifold, I have a silicon hose (grey) and it is more slim than the others and my T clamp can hold it tight enough. So I've put a worm clamp.
I need a smaller T clamp or a new silicon hose (4 ply or something) for it.

You're right, I will go full T clamp in the future ;)

Engine is out for rebuild!

https://www.miataturbo.net/attachmen...ine=1327414072


https://www.miataturbo.net/attachmen...ine=1327414072

Engine open but big surprise...

https://www.miataturbo.net/attachmen...ine=1327829840

rings broken

https://www.miataturbo.net/attachmen...ine=1327829840

And 3 pistons damaged

https://www.miataturbo.net/attachmen...ine=1327829840

https://www.miataturbo.net/attachmen...ine=1327829840

I was planning to keep the OEM pistons for the rebuild... :(

That is so strange looking... Your secondary compression rings show much less damage, and no extruding the groove out as in the top ring. Its probably a lean condition with some deto causing that.

Thanks for you analyse

Here's another picture

https://www.miataturbo.net/attachmen...ine=1327861312


For Info:
-rev limiter set at 5000rpm
-100miles done with the supercharger
-max boost 8psi
-AFR 10 at full throttle

Maybe rings were like this for before...

Picture of top of pistion? It looks like you can see some pocking of the aluminum near the top on the side which would indicate the piston was overheated. Again excessive lean condition indication. Still I've never seen piston ring do that to the top Lan. My first thought was who assembled this thing, but from your post it looks like Mazda did it! ;)

Piston n°1 (ring OK)

https://www.miataturbo.net/attachmen...ine=1327862518

Piston n°2 (ring KO)

https://www.miataturbo.net/attachmen...ine=1327862518

Uploaded with ImageShack.us

Those little light colored spots indicate detonation. What were you using to control the spark timing when the engine was in boost?

nice. but why,.. on my golf 2 rallye, it was removed and a autorotor screw type sc installed instead. much better(but noisy as nothinge else)

detonations... maybe when I was running without intercooler. Manifold's air intake was so hot.
I use 98 octane gasoline but it was not enough to prevent detonations at this time.

Temp is pretty irrelevant, you should still be able to tune the car to not det.

I've had extended 150degC intake temps on track, pulled the head and not a hint of detonation.

Well, I'm confused.

I though I was running in a kind of secure mode (8psi, 10 AFR, 5000rpm, 10 BTDC). So I don't know why.

Any ideas?

I realise that my spakplugs maybe a bit responsible, they're maybe too hot.
I will order NGK bkr7e-11

Did you tune whilst listening for det? Or just assume that it was all OK?

I didn't make any tuning yet. Only use theory.
I though old engine could handle 100miles like this.

Here, was the plan:

-Finish the install of the supercharger,
-rebuild the engine before going further. (it was needed...)
-make fuel and spark tuning

Maybe engine was "fragile" before supercharging it