ECUTune Stage III twin screw supercharger sign up

[Dessertrunner]

Now it makes sense thanks for explaining it to me, they are interesting numbers its great to be able to see what will happen.
I can see you will hate me for all the questions but here goes again, were is the intercooler before the SC or after. Reason I ask is if its after the SC then both are being feed with the same density air aren't they?

[svxistentialist]

Originally Posted by Dessertrunner

Now it makes sense thanks for explaining it to me, they are interesting numbers its great to be able to see what will happen.
I can see you will hate me for all the questions but here goes again, were is the intercooler before the SC or after. Reason I ask is if its after the SC then both are being feed with the same density air aren't they?

It would be the same as on Prezzers, the intercooler is after the blower. It has to be if you think about it. It is the heat of the blower or turbo compressing the air that causes it to heat up. You need to extract this heat back from the charge to get the extra oxygen into the engine.

In our case and LAN's case air is fed through the throttle bodies to the blower, blower compresses air and feeds through the plenum into the intakes. Because there is so little room between the blower outlet plate and the intakes we opted for injection as a means of charge cooling.

It would theoretically be possible to use a Jaguar XJR like system to cool the charge before it fed the intakes, but the amount of fabrication required to do it, including possibly raising the bonnet profile, is really pretty horrid. You would have to be keen and a very handy fabricator.

Joe

[Dessertrunner]

the 290 BHP comes from 7,960 rpm and the 340 BHP comes from 8,071 rpm were is the extra Oxygen coming from because as you said the cooler is after the SC so therefor the density will be the same for the air being feed to SC.
Tony

[svxistentialist]

You need to re-read your Autospeed calculations, particularly the Final Calculations bit at the end.

Air [or gas] density is a function of temperature and pressure, two things. What you need to calculate is the air density of the final ingested charge which goes into the cylinder.

The Autospeed calculations are based on a turbo, but it's the same thing really.

<<
So with an intercooler we have a temp of 61 °C at a boost pressure ratio of 2.36, compared with a non-intercooled 153 °C at a pressure ratio of 2.5.
>>

This in turn computes into the intercooled engine getting 2.1 times the air density of the non-compressed air, versus the non-intercooled engine only getting 1.75 times the air density of the non-compressed air. This is where the power difference lies.

Tony, don't get confused into thinking that air is like a liquid, and all the oxygen that is sucked past the intake is getting into the combustion process. It's not. Remember it is a gas being pressurised after the throttle bodies, and heat of pressurisation is causing a lowering of density, if cooling is not involved.

After the blower compressor, the air/charge is being forced into the plenum chamber, and from the pressurised plenum the engine takes what it needs. If the air in the plenum is not cooled and made more dense, then the engine is leaving behind a proportion of the oxygen in the plenum.

This is where the difference of 2.1 times air density versus 1.75 times air density comes in for the worked example in Autospeed. In turn, this causes the difference in theoretical hp output.

Joe

[Dessertrunner]

I get the density part on the engine side of the SC but I still have trouble saying the revs on the SC can be nearly the same ans you will get different power. Pressure is effected by final air temp. The intercooled engine will require the SC to pump more air to get the same psi as the uncooled. In simple terms if the air heats up as it is pumped through the SC then it will require SC to pump less to get the to the 9 psi.
Maybe I will have to think it through more I just can't get the part of the SC revs being simlar in both of your sheets.

Do you understand this part in the Autospeed calc

Theoretical outlet temp = 293 x (2.1)0.286
= 293 x 1.236

what maths is being done between the (2.1) & 0.286 to get 1.236 as I get 1.2306. Is it ment to be to the power of.
Tony

[IdeasMan]

Tony's right. Because a supercharger is a positive displacement compressor the volume of air displaced is the same. Therefore if the temp goes down the pressure must also. This is why top fuel drag racers run the risk of running nitromethane through the supercharger. The vaporizing fuel cools the air before it passes through the supercharger. Intercooling is still a good idea after the supercharger as the air is hotter and therefore easier to cool, but you would have to increase the speed of the supercharger to get the power increase benefit of this cooling. This is not really a bad thing as superchargers tend to increase in volumetric efficiency as their speed increases. Thermodynamic efficiency may not, You don't want the heat generated by your supercharger to overtake your intercooler.
Money, time, and space-wise a water injection system before the supercharger is probably your best option. Just don't run out of water!
Turbos are different, the cooling after the turbo will increase the charge density. Water injection before the turbo is a bad idea!! Turbos hate water!
Planes in WWII used a turbo and a supercharger in series without any intercooler. The turbo heated and compressed the cold thin intake air so the fuel would atomize, then the fuel was injected before the supercharger cooling the charge. The supercharger gave the final pressure boost. 1000+ Hp Sweet!

[Dessertrunner]

Thanks for that I get you, one last question can you or anyone help with the math's problem?

[svxistentialist]

I'll have a look at that Tony and check it out, I did not look too closely.

Joe

[Dessertrunner]

Thanks Joe it would be appricated.

[svxistentialist]

Originally Posted by Dessertrunner

Do you understand this part in the Autospeed calc

Theoretical outlet temp = 293 x (2.1)0.286
= 293 x 1.236

what maths is being done between the (2.1) & 0.286 to get 1.236 as I get 1.2306. Is it ment to be to the power of.
Tony

Tony, it seems to be correct to me, possibly you hit a wrong digit or something.

On my calculator (2.1) to the power of 0.286 gives me 1.2363878.

They used 1.236 which is correct to three decimal places.

Joe

[longassname]

i haven't really read through all that has been posted and haven't seen, used, or checked this uk software svxistensialist uses to figure out whatever for differnt compressors but I will say that some of the #'s I have seen posted as a result of that software don't jive with the compressor maps I have for the 1600ax compressor.

On a seperate note, cooler is always better and higher octane #'s are always better for higher compression. I've had e85 software out there for a long time now. That's ethanol injection guys. If you want to cool your intake charge run e85. As is the norm..the vanagon and sandrail guys have taken much more advantage of this than the svx guys have. It's there if you want it.

[XxMattrimxX]

Just wondering if this ever got fully out to production? Cost? and is it worth it!?

[Nemesis Destiny]

Wow, this is an old-ass thread, and one I was quite fond of. I'd forgotten about it.

[longassname]

They didn't fit under the hood as well as I had hoped. We had to use the smallest pulley possible, mess with the engine mounts, put spacers in the sub frame, and remove the insulation under the hood above the pulley to get clearance.

At that time the ECUtune firmware changes were not the "aggressive" versions we use now. AKA they required the ECU to use the knock sensors to learn in a large amount of advance on top of the primary ignition table. A couple cars did this well--many did not.

We were originally going to have the fabrication work done by someone else but somehow I ended up doing it myself and the machine work was done on a small, cheap, chineese, manual mill and lathe. The manifolds and pulleys were really beyond the capacity of the machines and as a result are a bit rough. With access to a nice big CNC mill it actually wouldn't be a big deal to clean the machine work up and true up the mating surfaces if I came accross one of the ones I made back then but I would definitely do so.

So long story short just the originals were made and they could use some refinement.

[XxMattrimxX]

well that is a shame. This would have been a really cool addition to the already dwindling parts list for SVX. Maybe someday, when pigs fly, hell freezes over, the sun goes black, and all life ceases to exist, we can have nice things.