Author Topic: BOOST  (Read 8864 times)

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Offline Sirdeuce

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BOOST
« on: February 01, 2011, 08:13:15 AM »
We all know about forced in duction, I hope anyway. The low end power of the roots supercharger. The rediculous high end potential of tubocharging. Best of both worlds? Twincharge! But here's one more to consider, Mike's going to have fun with this one! It's not new, been used to boost performance for some time now, but not talked about much from the street perormance crowd. Compound boost! Supercharge the engine? Yes! Add a turbocharger? Yes! At the same time? Yes! Supercharge the engine, turbocharge the supercharger! That;s right! Increase the supercharger's inlet pressure! Tune the low end power to get off the line with the roots charger, where it does the best increase in power! As the roots type charger tends to drop off at the upper RPM's where a turbo shines. Hmmm. Boost the inlet side of the superchargeer? Makes for some interesting tuning challenges. Say you are getting 10 pounds boost from your supercharger. Boost the inlet to 7 pounds, 1/2 atmospheric pressure. Now you have 15 pounds of boost, theoretcally of course. But the real advantage is the expanded powerband! 10 pounds off the line, but when the turbo comes on, you get the 15 pounds! And that would carry through to beyond where the supercharger drops off! Also, since you don't have to overdrive the supercharger as much the engine RPM can be raised! Imagine the possibilities! Only problem I can think of with the Toyota superchargers is the flourine coating an the impellers. Spinneing the SC12 and SC14 over 11,500 RPM is said to melt the coating. How would boosting the inlet affect this? Is the melting of the flourine due to the heat produced by the increase in pressure or just an effect from increased RPM?
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Offline Sirdeuce

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Re: BOOST
« Reply #1 on: February 01, 2011, 08:16:40 AM »
Another thing said about this is the parasitic losses from driving the supercarger. It's said that increasing the supercharger's RPM increases parasitic losses, so compounding should decrease the losses at higher boost levels as the RPM level remains lower per pound of boost. That's the claim anyway.
"I slept with faith and found a corpse in my arms on wakening; I drank and danced all night with doubt and found her a virgin in the morning."

Offline BigMike

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Re: BOOST
« Reply #2 on: February 01, 2011, 09:06:20 AM »
I'd be concerned about the high temperatures entering the blower. Chee has been talking to me about doing compound Turbos where one turbo feeds the inlet of a 2nd turbo.

I like the idea of a twin charger since our SC's use an electronic clutch. It must be great when the Turbo out boosts the SC and then the SC turns off. It would be like a quick shot of power just from the sudden reduction in parasitic losses!
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Offline Sirdeuce

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Re: BOOST
« Reply #3 on: February 01, 2011, 09:27:00 AM »
I've seen compound turbos on competition pulling tractors. Inagine three stages of turbos boosting to 200+ psi on a diesel! Massive power! But only good for the short 100 yard pull. The temperature of the inlet is my main concern on the S/C setup though. Although, since low boost pressures are to be expected to boost the S/C, temps would probably be manageable. Water injection may be a way to control that problem. Set it up with a thermal control system. Second intercooler? Power gain vs weight gain is a consideration. Being different is a big consideration. But the concept is intrigueing nonetheless.
"I slept with faith and found a corpse in my arms on wakening; I drank and danced all night with doubt and found her a virgin in the morning."

MisgusNapolly

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Re: BOOST
« Reply #4 on: October 07, 2014, 08:53:10 PM »
Wonderful !! you make me to great experience. I will do it same you.

Offline BigMike

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Re: BOOST
« Reply #5 on: October 08, 2014, 12:31:35 PM »
Wonderful !! you make me to great experience. I will do it same you.
Hmmmmm.....
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Offline yoshimitsuspeed

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Re: BOOST
« Reply #6 on: October 27, 2014, 09:28:14 AM »
Hey guys, I just found this board.
Looks like you have some interesting discussions so I decided to join up.

Compound boosting with a supercharger can work but in order to make it work well you need to put an intercooler between the first compressor and second compressor. Otherwise your outlet temps will be much higher than they would be with just a turbo because the supercharger is less efficient.
If you do intercool between compressors you could actually have lower intake temps than you would with one turbo and one intercooler.

Teflon melts at such a high temp that I have never believed the theories that it does in the SC.
I believe what happens is the rotors being exposed to more heat and having less thermal mass expand more than the housing causing them to hit the housing and or each other.

I believe mk1noob is still compound boosting his M90 AW11. I don't hear from him much these days but last I did he was running about 20 PSI and getting ready to switch to E85 and go big.

Offline BigMike

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Re: BOOST
« Reply #7 on: October 29, 2014, 06:09:17 PM »
Hey yoshimitsuspeed!!

Thank you for joining our small home on the net!!! :driving:

Looking forward to seeing ya around some :thumbs:

Regards,
BigMike
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Offline Sirdeuce

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Re: BOOST
« Reply #8 on: October 30, 2014, 11:15:11 PM »
Hey Yoshi! Surprised to see you here. Hope you have as much fun here as we have.  I read your posts on turboing an NA AFM setup and am thinking of possibly attempting a project. Not looking for a lot, but would like to have a little more torque. Would be nice to climb Cuesta pass without dropping a gear or two. Until then I actually have a reason to spin that little rev happy monster!
"I slept with faith and found a corpse in my arms on wakening; I drank and danced all night with doubt and found her a virgin in the morning."

Offline yoshimitsuspeed

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Re: BOOST
« Reply #9 on: October 31, 2014, 12:48:16 AM »
Nice.
Yeah you aren't going to tear the rollers off any dynos with the stock pistons and ECU but it can make a huge difference in situations just like you say. DIfference between needing to drop to third vs being able to stay in fourth or even fifth and cruise right up.
Also the difference between sitting behind someone for miles because you don't have what it takes to get past in a tight spot or being able to whip out, punch it and fly by.
Hope to see a good build thread if you do it.

Offline BigMike

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Re: BOOST
« Reply #10 on: October 31, 2014, 12:15:46 PM »
Also the difference between sitting behind someone for miles because you don't have what it takes to get past in a tight spot or being able to whip out, punch it and fly by.
This.

While my car was down these past 2 months I was driving around my family's automatic Saturn SC1. Just shoot my in the face, right between the eyes. I felt like I was Takumi when he got pissed and drove Itsuki's AE85 for the first time. You know where he'd see that moment to pass or make a move, and hit the accelerator, and then nothing would happen? This was the difference, multiplied 10 fold, between a lightweight supercharged 6-spd and an automatic PILE OF CRAP. Now that I'm back in my MR2, I can make so many position changes on the highway without downshifting and doing so in a limited window of time as to not attract too much attention (aka less time speeding = less chance for speeding ticket).

Bill, I would also like to see you turbo your 4A-GE. Do you even have a turbo laying around? Chee might have a CT26. I know of a guy in Visalia who might be interested in making a custom turbo manifold for you.

Regards,
BigMike
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Offline Sirdeuce

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Re: BOOST
« Reply #11 on: November 04, 2014, 12:15:16 PM »
Curious? I wonder if a mild boost from a supercharger could be used instead of the turbo with the NA ECU.
"I slept with faith and found a corpse in my arms on wakening; I drank and danced all night with doubt and found her a virgin in the morning."

Offline yoshimitsuspeed

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Re: BOOST
« Reply #12 on: November 06, 2014, 06:56:17 PM »
It's possible. mk1noob did it and detailed it pretty well in his 4agez threads on the mr2oc.
He also went pretty quickly from SC12 to M90 to twincharged because neither SC setup got him very far. Like me he lives over 5000 feet which devastates pressure ratios and a SCs capability.


There are a couple big things I don't like about the idea.
First is that the SC12s are getting older, rarer and more expensive. They also can't be rebuilt fully. If the internal bearings go it's no more than a fancy paper weight.
Any other SC will take a lot more time and money to install than a turbo and still have much less capability.
If you did do this and decided you wanted more than 200 hp down the road you would need to completely redo your entire system.
If you did a twinscrew you might get over 250 but it would add another $2k or more to the build.

People always like to complain about spool but I like to remind people that the SC12 or M62 are only good for about 180 WHP with a lot of supporting mods. An SC14 or M90 might break 200 with a lot of supporting mods.
The OEM turbos that are considered to be too small and spool insanely quick like the DSM T25, Nissan T25s, 13b, 13T etc can all make well over 200 WHP. With a good tune people have made over 250.
A turbo that maxed around 180 WHP would spool so damn fast that over 3000 RPM you would have a hard time telling it apart from an SC12.

Offline Sirdeuce

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Re: BOOST
« Reply #13 on: November 06, 2014, 09:03:12 PM »
Naw, the parts I have at my disposal are an Eaton M62 and a turbo from my '86 Mitsu Tredia. Not sure nomenclature on that turbo. I think I read T18 somewhere.  That was a fun little ride. Needed a better trans though. I'm old, kinda, and basically destroyed my body, so gobs of power are no longer in my wishbook. I just want about 30% more than stock. I won't even consider using my NOS kit any more. But the idea of boosting the stock AFM ECUed engine intrigues me.
"I slept with faith and found a corpse in my arms on wakening; I drank and danced all night with doubt and found her a virgin in the morning."

Offline Sirdeuce

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Re: BOOST
« Reply #14 on: November 06, 2014, 09:11:05 PM »
How far down stream can the turbo be mounted before the exhaust gasses lose their potency? Using the stock exhaust manifold with an adapter to the turbo or modifying the downpipe after the 2-1 merge. Thinking of making it semi-easy to change back and forth every 2 years for our smog Nazis. I also have an intercooler from a mid 90's Supra.
"I slept with faith and found a corpse in my arms on wakening; I drank and danced all night with doubt and found her a virgin in the morning."