The Chupacabra. Quad Turbo Vette Kart.
05-21-2017, 10:35 PM
#1
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The Chupacabra. Quad Turbo Vette Kart. It started as an 89 Corvette I bought last year. The owner said it didn't run. Turned out to be a bad wiring harness that was corroded at the firewall connector. I fired it up, pulled it apart and parted it out to break even.
I had the idea for a quad setup when I bought the car last year.
I wanted something absolutely ridiculous, so I yanked off the body, sourced a cheap engine, and ordered everything.
-89 Corvette.
-Roughly 2000 lbs w/o driver.
-Bone stock 4.8, unknown miles. Valve covers have never been off.
-Manual TH400
-Quad 50mm Turbos.
-Microsquirt with some custom additions.
This is the first iteration. I plan on going through 3 phases with the car.
I'm not doing a project log because I can't edit posts and don't want to go through the hassle, but I'll post constant updates.
It'll be at a Dyno Day I'm throwing at a buddies shop this coming weekend, and I have a car show and burnout contest the following weekend. I don't plan to disappoint.
I had the idea for a quad setup when I bought the car last year.
I wanted something absolutely ridiculous, so I yanked off the body, sourced a cheap engine, and ordered everything.
-89 Corvette.
-Roughly 2000 lbs w/o driver.
-Bone stock 4.8, unknown miles. Valve covers have never been off.
-Manual TH400
-Quad 50mm Turbos.
-Microsquirt with some custom additions.
This is the first iteration. I plan on going through 3 phases with the car.
I'm not doing a project log because I can't edit posts and don't want to go through the hassle, but I'll post constant updates.
It'll be at a Dyno Day I'm throwing at a buddies shop this coming weekend, and I have a car show and burnout contest the following weekend. I don't plan to disappoint.
Which turbos are those? Price? 
05-22-2017, 09:58 AM
#7
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DNA turbos. I have like $1500 in the whole setup, including materials for the manifolds and all of the feed/drain lines and fittings.
I think the turbos were $170 each when I bought them ~6 months ago. The non anti-surge housing versions are $30 or so cheaper per turbo.
A buddy of mine made 588 on a Dyno Dynamics with a stock 4.8 and a pair of these at 17 lbs. The biggest problem is the openings in the housing for the internal gates are only 7/8" so the 8 lb gates are useless. Now that he has a 5.3, he hits the 17 lbs boost cut at like 5500 RPM. With the 4.8, he was creeping to 17 PSI at the limiter. I figure with 4 of them, I have a fighting chance.
Each 7/8" wastegate opening has .6 square inches of area, so 2 of them gives me 1.2 square inches of wastegate flow compared to ~1.7 for a 38mm wastegate. Luckily, there is enough room there to open up the ports for the internal gates to 1.125" for a total are of 2 square inches for each bank.
I have compressor maps for same sized turbos, probably what these are based off of.
Driving 1.2L each, these things are in peak efficiency at ~18 lbs, and still near peak up to almost 30 lbs. I might actually gain a bit of efficiency if I ever swap to an aluminum 5.3 (planning on this later).
For a stock 4.8, throttle response on this thing is extremely snappy. Might have something to do with the fact that 4 turbines isn't nearly as restrictive as 2, and the 4 of them move a LOT of air at idle. Even with no IAC and the throttle blade closed completely, I was having trouble keeping the idle RPM down.
I've been working on a project that expands microsquirt. So far, I've got it controlling an IAC and dual fans using the CANBUS on micro. It also looks like I'll have it controlling a shift light, PWM boost control, nitrous (Yeah, this has nitrous as well), and I'm working on getting it to read the 4 ABS sensors on the car for boost based traction control.
I think the turbos were $170 each when I bought them ~6 months ago. The non anti-surge housing versions are $30 or so cheaper per turbo.
A buddy of mine made 588 on a Dyno Dynamics with a stock 4.8 and a pair of these at 17 lbs. The biggest problem is the openings in the housing for the internal gates are only 7/8" so the 8 lb gates are useless. Now that he has a 5.3, he hits the 17 lbs boost cut at like 5500 RPM. With the 4.8, he was creeping to 17 PSI at the limiter. I figure with 4 of them, I have a fighting chance.
Each 7/8" wastegate opening has .6 square inches of area, so 2 of them gives me 1.2 square inches of wastegate flow compared to ~1.7 for a 38mm wastegate. Luckily, there is enough room there to open up the ports for the internal gates to 1.125" for a total are of 2 square inches for each bank.
I have compressor maps for same sized turbos, probably what these are based off of.
Driving 1.2L each, these things are in peak efficiency at ~18 lbs, and still near peak up to almost 30 lbs. I might actually gain a bit of efficiency if I ever swap to an aluminum 5.3 (planning on this later).
For a stock 4.8, throttle response on this thing is extremely snappy. Might have something to do with the fact that 4 turbines isn't nearly as restrictive as 2, and the 4 of them move a LOT of air at idle. Even with no IAC and the throttle blade closed completely, I was having trouble keeping the idle RPM down.
I've been working on a project that expands microsquirt. So far, I've got it controlling an IAC and dual fans using the CANBUS on micro. It also looks like I'll have it controlling a shift light, PWM boost control, nitrous (Yeah, this has nitrous as well), and I'm working on getting it to read the 4 ABS sensors on the car for boost based traction control.
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05-22-2017, 10:34 AM
#9
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05-22-2017, 10:49 AM
#11
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My actual first start attempt didn't go so well. My TPS was reading backwards so at no throttle it was reading 100%, activating the flood clear in the micro and killing the injectors, but I edited that part out of the video haha.
05-22-2017, 11:46 AM
#13
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Its not a stock PCM. Microsquirt is usually a bit more issue to get fired for the first time because every engine is modified to it as there is no basis to start from. I just happened to have done an identical setup already minus 2 turbos and 20 lb/hr of injector flow.
05-22-2017, 06:33 PM
#16
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So the transmission I had built doesn't work. No fluid flow.
Either the filter has fallen off, seals are shot, or the pump took a dump. The guy had it completely apart when I bought it, and he put it back together with new parts. Apparently he skipped something.
But, with the wideband pegged rich, I decided to give it a little throttle. Very unique exhaust sound to say the least.
Either the filter has fallen off, seals are shot, or the pump took a dump. The guy had it completely apart when I bought it, and he put it back together with new parts. Apparently he skipped something.
But, with the wideband pegged rich, I decided to give it a little throttle. Very unique exhaust sound to say the least.
05-22-2017, 07:58 PM
#19
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Cylinders are unevenly paired, and I tried to make sure the cylinder firing 2nd was 50% longer than the first.
Sounds like a Subaru at idle. Sounds like a solid roller small block from drivers seat.
Sounds like a Subaru at idle. Sounds like a solid roller small block from drivers seat.
