I've heard you say stuff like this in many threads, but I never see anything solid to actually convince me of what you're saying. It's going to take something tangible to convince me that stuffing big turbines in tiny little housings will maximize performance while maintaining spool. The theory sounds great, but what do you have to back it up? If your observations are minute enough to notice a 250rpm delay in spool, you gotta have a log or something...

GST with PSI said:

I just don't understand why anyone would want to run a 14b at 25psi in any configuration. Hell, most of the 14b max effort guys aren't running those boost levels. Plot any mass flow rate @ a 2.7 pressure ratio on the 14b compressor map and you're just making hot air. What fuel does this planned setup of yours run on? Better not be pump, that's for sure.

I still disagree with 94awdcoupe on his theories about the 6cm housing. Pairing that housing with a larger turbine seems utterly pointless to me. However, some of the 20G variants he's mentioning would be far better than any 14b/16g setup. The 6SL2 turbine paired with some of the lighter billet wheels can be made to spool ridiculously fast. And, those compressor wheels operate in efficiency ranges that will actually net you some decent power.

Speaking of power, what's your target?

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I'm shooting for 55lbs of air volume through the turbine, but something I may not have mentioned before is I intend to run a large external gate off the manifold to help bypass some of that air volume. To answer your question it was pushing a TON of hot air, but considering my fuel and a very conservative tune, it was not beyond an appreciable point. I run home brew E90 and about 10* timing at MBT and 18* total. This is on stock cams at 4500ft DA so the compressor air temp was fairly irrelevant. I tuned the car for ZERO knock and have over 100 passes on it in the mid 12s, 3300lbs w/driver, 150k on the ODO, FMIC/Intake/Exhaust that's it. At my altitude I need the extra boost to get the performance I need from it.

The theory of a larger wheel in a small housing is proving to be the norm on many of the newer record setting turbos being produced these days. The CEA 6262 comes to mind for starters. There's two components in the hotside that represent a flow restriction, the turbine volute/nozzle and the wheel itself. You can decrease the wheel size to reduce the restriction (like many of the OG Garrets) but then you lose captured energy through blade surface area and have a turbo that struggles at higher revs. The other option is to tighten the nozzle area and increase the wheel size which may seem counter intuitive, but there's plenty of exhaust pressure to increase the flow rate of the nozzle, while using the wheel area to increase dynamic flow through the housing and improve efficiency on the top end. It's very theoretical but I can see how this setup is changing the way we view turbo design for modern 4 cylinders in the industry.

In the end for my setup, the comp wheel is irrelevant. Whether it's making 25lbs of air or not the primary power adder will be responsible for the over all airflow curve, the turbo is secondary. I just need a hotside that will flow enough volume to not represent a significant restriction to the overall system. In theory whatever worked to reduce the spool time of any of the aforementioned 20/16G turbos without increasing restriction will work on my 14b.

94awdcoupe said:

the 11 blade 6sL2 wheel is indeed a lightweight fast spooling wheel. I used a 20g with this turbine and very impressed with it.. I think it would work VERY well in a machined 6CM housing. there is also a 9 blade version of this wheel that i have not used or even seen yet. but that may be what you are looking for. the 6H wont spool as fast. you havent stated how much WHP you are making on the setup. that would be helpful to give best advice.

there is a guy on evo m who built a 20g (billet 11 blade) with 5H 9 blade turbine. he said it spooled faster than the stock 16g. he had dyno graph for proof. the 9 blade wheels are the lightest. so they should spool the fastest.

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Power numbers see above.

I was hoping you had tried the 9 blade wheel by now, but in your opinion do you think it would reduce spool time more than the 11 blade and reduce backpressure an equal amount? Also how does the 11 blade SL2 compare in flow rate to the 06 and 06H?

I was always under the impression that the 9blade sl2 was slower spooling than the 11blade as the less blades were meant for higher boost, less area higher speed thought the 9 blade was suppose to act like a clipped turbine? Turbine weight will also effect spool? I did a lot of reading about the sl2 20g and didn't find a lot of solid info or got confused with all the combinations. I was planning to have an sl2 20g built but couldn't have one built for what the hta68 cost a month ago.

So is the 9 blade in the hta68 an sl2 9 blade or a turbine from the tf06-18k? The 68 compressor is suppose to be closest to an 18g, so couldn't a billet 20g wheel (w/machined cover) be used for more overall flow 51lb/min+? When researching the sl2 20g I did find that the difference between the e316g and 5h 18g was minimal people would say to go either e316g or 20g. It seems odd then that the 68 has an 18g compressor?

Id like to get my extra 7cm housing machined to fit the hta68 if its not too pricy id have a 6cm done as well just to try some different options. As far as super 14b the fp 8cm housing may fit what you are looking for fiend, and are you building a compound turbo setup?

as far as notable results. there is curt brown. he used a 7cm red and went 9.6 at 143 on it. I did the calcs and he was making 560whp on a 6h/7cm housing. when he switched to fp3065 he had a 565whp dyno graph and went pretty much the same times. when asked he said the 3065 was easier to drive with better boost recovery and slightly faster spool. there was also a guy ten years ago that was one of the first pioneers to AWD A/T. he used the red in 6cm to spool the turbo. his car was record setting at the time. low 10s in a 2G.

i havent played much with these after market turbines. while i was impressed with the performance of the 11 blade 6SL2 i was less impressed with its reliability. the blade just lost a fin after about 9 months in the car. it was hitting around 27psi. I have seen the same happen to aftermarket 6h wheels as well. I have never seen it from genuine mitsu wheels. a lot of people use these turbines with success. but keep in mind my 9 months on street would equate to ten years on a track car. i personally like to stick with genuine mitsubishi wheels. there is a factory 11 blade 5H wheel. and a factory 11 blade 6H wheel. both have modern aero. i would use those if you can get your hands on one. I posted data on the factory turbos they came in. you have to find cores. you wont get one from FP or Mitsu.

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factory 11blade 5H

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factory FP red

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there is no factory 6SL2 wheel. there is however the wheel from the factory made TF06-18K. its is slightly bigger than the 6SL2 wheel. I had one here and the turbine did not fit into housing cut for 6SL2. but be pretty hard to get genuine one of those as well. there is a taiwan aftermarket one already. thats what the FP 68 is currently made with. that why he can sell them so cheap. the TF06-18k is factory made mitsubishi evo X turbo. 1650 from FP. I am on the evo X forums regularly as i run evo X based turbo on my car. i have never seen a blown one for sale. and blown would likely mean blown turbine.

as far as less blades on turbine side spooling slower I am not sure about. look at the stock 12blade 5h and the newer 11blade. the wheel is made taller. same thing happen with the 6H4 wheel. they have less blades but each blade is bigger. the 6SL2 wheel with 11 blades was not made taller. its same height as 5h and very open lightweight design.

6SL2 VS 5H

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boost recovery would certainly be faster with whichever wheel is lighter. the 9 blade versions are lighter.

TSi-Rocket said:

I was always under the impression that the 9blade sl2 was slower spooling than the 11blade as the less blades were meant for higher boost, less area higher speed thought the 9 blade was suppose to act like a clipped turbine? Turbine weight will also effect spool? I did a lot of reading about the sl2 20g and didn't find a lot of solid info or got confused with all the combinations. I was planning to have an sl2 20g built but couldn't have one built for what the hta68 cost a month ago.

As far as super 14b the fp 8cm housing may fit what you are looking for fiend, and are you building a compound turbo setup?

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Negative, not a compound turbo. I'll discuss my setup more once I get some results from it. I don't want to look like an idiot if it totally fails


There are two factors that determine the point where a typical turbine wheel will capture enough energy to generate a positive energy return, and that's blade configuration, and mass. The blades shape, pitch, angular moment, dimensions...all affect what range the wheel will transfer energy to the compressor. However mass is just as critical in accelerating the turbine wheel to threshold speed allowing the blade design to reach it's energy return limit sooner. Given the same wheel configuration and design simply removing weight from the wheel will allow the turbo to spool the compressor wheel faster. But that is where the issue at hand becomes convoluted. With the wheels we've been discussing the designers primarily have been removing blades to reduce wheel mass, but that also reduces the number of machines to capture energy from the exhaust and return it to the compressor. This will increase airflow through the turbo making it more efficient at high RPMs, in theory increasing spool time as well unless the blade shape is altered to compensate. The reduced mass is going to help offset the loss of a blade, but it wont offset the loss completely, there would have to be an alteration in the wheel before any improvement will be realized. Without knowing what the designer's primary goals were with the design it's very hard to determine what the outcome will be without field testing. That's where my interest in posting this question came from in hopes someone else has tried a similar combo and could report their findings.

94awdcoupe said:

as far as notable results. there is curt brown. he used a 7cm red and went 9.6 at 143 on it. I did the calcs and he was making 560whp on a 6h/7cm housing. when he switched to fp3065 he had a 565whp dyno graph and went pretty much the same times. there was also a guy ten years ago that was one of the first pioneers to AWD A/T. he used the red in 6cm to spool the turbo. his car was record setting at the time. low 10s in a 2G.

i havent played much with these after market turbines. while i was impressed with the performance of the 11 blade 6SL2 i was less impressed with its reliability. the blade just lost a fin after about 9 months in the car. it was hitting around 27psi. I have seen the same happen to aftermarket 6h wheels as well. I have never seen it from genuine mitsu wheels. a lot of people use these turbines with success. but keep in mind my 9 months on street would equate to ten years on a track car. i personally like to stick with genuine mitsubishi wheels. there is a factory 11 blade 5H wheel. and a factory 11 blade 6H wheel. both have modern aero. i would use those if you can get your hands on one. I posted data on the factory turbos they came in. you have to find cores. you wont get one from FP or Mitsu.

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According to my study the Red uses a 6H wheel so if the 2G auto guys getting solid results with that setup in a 6cm housing that and based on your other experiences is enough for me to give it a try. I'm going to buy a tiawanese 6SL2 9 blade and have a 6cm housing machined for it. I'll be logging backpressure so if that doesnt seem to be flowing enough exhaust I will step up to a 7cm and shouldn't have an issues from there. I am concerned about manufacturing quality but being as I cant get these wheels from an OEM supplier all I can do is cross my fingers. If it begins to have reoccurring quality issues I'll have to go another route I suppose. Thanks for all your advice, keep an eye out for a detailed thread on my setup middle of 2016.

GST with PSI said:

I just don't understand why anyone would want to run a 14b at 25psi in any configuration. Hell, most of the 14b max effort guys aren't running those boost levels. Plot any mass flow rate @ a 2.7 pressure ratio on the 14b compressor map and you're just making hot air. What fuel does this planned setup of yours run on? Better not be pump, that's for sure.

If I were in your position, I'd at least consider a 16g variant of some sort with a clipped TD05H turbine in a 7cm housing. I believe that would net some of the flow characteristics you're looking for without dramatically sacrificing spool.

I still disagree with 94awdcoupe on his theories about the 6cm housing. Pairing that housing with a larger turbine seems utterly pointless to me. However, some of the 20G variants he's mentioning would be far better than any 14b/16g setup. The 6SL2 turbine paired with some of the lighter billet wheels can be made to spool ridiculously fast. And, those compressor wheels operate in efficiency ranges that will actually net you some decent power.

Speaking of power, what's your target?

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you don't want a clipped 16g in a 7cm housing. I actually had an 18g with a 10 degree clip on the turbine and it sucked for response. My T04E 50-trim actually felt more responsive and made more power from 3600+.

mean4g said:

I actually had an 18g with a 10 degree clip on the turbine and it sucked for response.

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Which is exactly why I never suggested a clipped 18G or a 50 trim. A clipped 16g in a 7cm housing will definitely spool below 3600 RPM. If it doesn't, you're doing something seriously wrong.

GST with PSI said:

Which is exactly why I never suggested a clipped 18G or a 50 trim. A clipped 16g in a 7cm housing will definitely spool below 3600 RPM. If it doesn't, you're doing something seriously wrong.

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18g is not much different from a 16g, only 2MM difference on inducer. They spool almost identical. 18g just has a bit more peak flow. If the 18g sucks with a clipped TD05H, you think a slightly smaller compressor wheel that flows less will be any better? 10 degree clip cost me 200 RPM of spool, and it did make 20 pounds at 3600 RPM BTW...The 50 trim just made more power at 3600. XX spool to XXXX RPM is pretty irrelevant when it makes less power. I am not a fan of clipped TD05H turbines because you loose the TD05H turbine advantage of the quick spool and you gain very little in peak airflow. It's just a bad trade off. There are better options than a clipped TD05H-16g was my point to include an old school T04E 50trim.

You're the only one I've ever heard of loosing a significant amount of spool on a clipped turbine, which leads me to believe it's a problem with something in your setup, not a problem with using a clipped turbine.

My buddy Dan runs an E316G with a clipped turbine and he's got zero issues with spool. His Talon also goes 12.9 on that 16G, which flows upwards of 40lbs/min. Logs will verify if you've got any doubts.

not only that. 50trim would be down 30-40tq min at 3600rpm. nothing he said makes sense.

94awdcoupe said:

not only that. 50trim would be down 30-40tq min at 3600rpm. nothing he said makes sense.

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I know you're a pretty strong advocate for a smaller housing, bigger turbine; but what are your thoughts on a small to medium housing with a smaller clipped turbine?

GST with PSI said:

You're the only one I've ever heard of loosing a significant amount of spool on a clipped turbine, which leads me to believe it's a problem with something in your setup, not a problem with using a clipped turbine.

My buddy Dan runs an E316G with a clipped turbine and he's got zero issues with spool. His Talon also goes 12.9 on that 16G, which flows upwards of 40lbs/min. Logs will verify if you've got any doubts.

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I don't remember where I read it now, but apparently FP found a significant performance loss from clipping a TD05, primarily because the boost dynamic was altered without providing much improvement in flow. I have thought about clipping the stock wheel and dropping it in a 7cm, but the bigger housing alone changes spool dramatically in my personal experience. I think you would be better off just running a bigger wheel in a 7cm because if you are going to lose spool might as well gain the advantage of MUCH higher flow through the hotside.

Does your friend Dan have any logs he would post? Is it an MHI E316G? I'd just like to know how much spool changed with the clipped wheel. Not to criticize him but my car is significantly faster with a bone stock engine and unmolested 14B, but I don't know what kind of driver he is or anything else about the setup so IDK if those are factors. I can say from experience I went from a 7cm 14B on another car to a 6cm 14B and picked up nearly 5mph without any other changes. The turbo was much laggier in the 7cm.

GST with PSI said:

You're the only one I've ever heard of loosing a significant amount of spool on a clipped turbine, which leads me to believe it's a problem with something in your setup, not a problem with using a clipped turbine.

My buddy Dan runs an E316G with a clipped turbine and he's got zero issues with spool. His Talon also goes 12.9 on that 16G, which flows upwards of 40lbs/min. Logs will verify if you've got any doubts.

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Didn't say mine didn't make power up top for what it was. It was just lazy, and did spool significantly slower.

94awdcoupe said:

not only that. 50trim would be down 30-40tq min at 3600rpm. nothing he said makes sense.

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50T at 3600 was at 15-16 pounds of boost FYI.

AWD_FIEND said:

Not to criticize him but my car is significantly faster with a bone stock engine and unmolested 14B

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His Talon is full weight with the mods in his profile, not some gutted go-kart. He's always been on the MHI E316G with a clipped wheel, so I have no idea how much spool changed after clipping the wheel. I know it spools just as quick as any E316G I've ever had on a car.

When you say you dropped your 14b in a 7cm housing and it was much laggier, what's that equate to in RPM? Anytime someone says 14b and lag in the same sentence, it immediately leads me to believe there's a problem...And not with the turbine housing.

Oh, and definitely in for a vid of your 12x run on a 14b with a bone stock motor. You got one, right?

Back around 03 people were doing basic mods ( k$n, exhaust, no spare tire and tools, and boost controller), running race gas, and got into the 12's. Im sure driver mod had something to do with it. The other mechanical parts of the cars were also in better shape 12 years ago. With age wiring will deteriorate with vibration, heat ect which can effect power, bushings wear out, drive shafts need rebuilt, ect but with a fresh car I think 12's would be possible with not a whole lot of mods.

I for sure noticed some lag between the 6cm and 7cm 14b but not enough to bother me as it still spools fast with the 7cm, but the pull in the higher rpm was worth it to me.

GST with PSI said:

I know you're a pretty strong advocate for a smaller housing, bigger turbine; but what are your thoughts on a small to medium housing with a smaller clipped turbine?

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what I do know about clipping the 5h wheel. burshur built and sold hundreds of "buschur 20g" turbos. when asked why they had a 20 degree clip he replied there was a measured 80psi back pressure at 29psi unclipped 5h. the clipping resulted in lowering that pressure to 60psi. the second thing is those turbos were the most unreliable turbos ever built. likely none still running today. the extreme clip removed too much mass from the wheel. I believe that resulted in the bearings and thrusts getting torn up quickly. there are combustion shock waves these parts must absorb. similar to lightweight flywheels not absorbing harmonics and drive shafts get noisy..

mean4g said:

you don't want a clipped 16g in a 7cm housing. I actually had an 18g with a 10 degree clip on the turbine and it sucked for response.

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10 degrees would do absolutely nothing to drastically-alter the spool characteristic of a turbo using a TD05H turbine. There had to be some other issue.

mean4g said:

18g is not much different from a 16g, only 2MM difference on inducer. They spool almost identical. 18g just has a bit more peak flow. If the 18g sucks with a clipped TD05H, you think a slightly smaller compressor wheel that flows less will be any better?

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In my opinion, the 18G compressor kinda sucks in general. Do they make power? Absolutely- but they don't do anything that a well-tuned Evo III 16G setup can't do, and the Evo III will do it spooling faster.

If you were to compare the standard Big 16G, 18G, and 20G they would get laggier and airflow would improve in that order of succession....but the Evo III is a newer-design than any of the previous three and had thinner blades as well as a much smaller hub, so there is more blade surface despite the inducer being 2mm-smaller which gives the Evo III 16G an airflow advantage.

mean4g said:

10 degree clip cost me 200 RPM of spool

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You ran the same turbo back-to-back clipped vs. unclipped and noticed a loss? Not singling you out, just trying to get some hard evidence of such a low-angle clip causing a noticeable loss in spool. I've built plenty of TD05H turbos over the years using turbine clips as aggressive as 25* like the three examples below and never had an issue with spool or reliability of the unit.

mean4g said:

I am not a fan of clipped TD05H turbines because you loose the TD05H turbine advantage of the quick spool and you gain very little in peak airflow.

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It's not necessarily a mod done to target peak flow as much as reducing drive pressure, EGT's, and making the car a bit easier to tune on lower-quality fuel when using a large compressor on a smaller turbine. Although the result of a more-aggressive tune or a higher boost level in relation to the clip can indeed improve performance and airflow.

You can't make a small turbine flow like a large turbine no matter how much you clip it just like you can't make a large turbine spool like a small turbine unless you cut down the turbine a/r and then you're right back where you started from with restriction. Given two turbos using the same compressor, one with a larger turbine is going to light up slower and have longer transient boost response due to the physical size and mass of the wheel, but will typically have less turbine drive pressure than a smaller turbine.

I'll typically recommend a smaller turbine (possibly clipped) over a larger wheel for a street-driven car or E85-powered auto-x car, then the larger turbines are better for drag builds or a performance street build where low-quality fuel is all that is available for use.

94awdcoupe said:

what I do know about clipping the 5h wheel. burshur built and sold hundreds of "buschur 20g" turbos. when asked why they had a 20 degree clip he replied there was a measured 80psi back pressure at 29psi unclipped 5h. the clipping resulted in lowering that pressure to 60psi. the second thing is those turbos were the most unreliable turbos ever built. likely none still running today. the extreme clip removed too much mass from the wheel. I believe that resulted in the bearings and thrusts getting torn up quickly. there are combustion shock waves these parts must absorb. similar to lightweight flywheels not absorbing harmonics and drive shafts get noisy..

Click to expand...

Gotta disagree completely with the reliability thing. We ran a heavily clipped TD05H 20G built by FP (who built Buschur's) for many years, running 11.0s multiple times. After the car moved up to a bigger setup, the turbo was passed around to no less than 3 people, then back to the original owner on his new FWD auto car. It finally developed a bit of shaft play recently from what I believe was oil contamination and not the fault of the turbo. It's been by far the most reliable TD05H based turbo I've ever had personal experience with, and I'd have no reason to believe the reduced thrust load from the clipping hasn't played a big part in that.

Steve93Talon said:

Gotta disagree completely with the reliability thing. We ran a heavily clipped TD05H 20G built by FP (who built Buschur's) for many years, running 11.0s multiple times. After the car moved up to a bigger setup, the turbo was passed around to no less than 3 people, then back to the original owner on his new FWD auto car. It finally developed a bit of shaft play recently from what I believe was oil contamination and not the fault of the turbo. It's been by far the most reliable TD05H based turbo I've ever had personal experience with, and I'd have no reason to believe the reduced thrust load from the clipping hasn't played a big part in that.

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no problem. but I would strongly disagree with having one be reliable so you call them all reliable.

GST with PSI said:

His Talon is full weight with the mods in his profile, not some gutted go-kart. He's always been on the MHI E316G with a clipped wheel, so I have no idea how much spool changed after clipping the wheel. I know it spools just as quick as any E316G I've ever had on a car.

When you say you dropped your 14b in a 7cm housing and it was much laggier, what's that equate to in RPM? Anytime someone says 14b and lag in the same sentence, it immediately leads me to believe there's a problem...And not with the turbine housing.

Oh, and definitely in for a vid of your 12x run on a 14b with a bone stock motor. You got one, right?

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The car that had a 14b with 7cm housing was not my car but rather a vehicle I tuned. The car was BONE stock other than a 3" exhaust and tune. Still had the sidemount. Admittedly I know nothing about the turbo before I got my hands on the car other than the owner reporting a 7cm, which I confirmed visually. The car had a very lazy powerband and the turbo would not hold more than 17psi with the actuator locked shut. I instantly assumed boost/exhaust leak, tested for both and confirmed my suspicions. Repaired every issue and the car would hold 19psi until about 5k then fall to 15psi still exhibiting the same lazy powerband. The turbo didn't hit full boost until about 3400rpms. I decided the issue may be internal to the 14b so I removed it and everything on the CHRA checked out. So I threw on a mint 6cm and took it for a pull. Instantly the familiar 14b powerband was there and the turbo hit 24psi and held it to redline. Took it to the track, the cars previous best was 103.5mph and first run out of the gate was 107.8. My conclusion was the 7cm lost more comp flow than it gained turbine flow, although I didn't play around with the small turbos until recently so I can't say my results are typical. As far as I can see the 7cm is pristine and functions properly, I even intend to try it on a 16g car to see if it was simply a mismatch of compressors.

Regarding my car, of course I have video of it, although I don't think it's all that unique. I'll post the timeslip if you want to see the run. It's actually my daily driver in the winter because it's awd and a pile of shit so I don't care if the roads destroy it. It doesn't have the back seats but that's primarily to fit more luggage with the system in the hatch. It weighs 3100 as I race it with 1/2 tank of fuel sans driver. I add another 190. Engine has 150k on it and 120-135 compression but hasn't been opened since it went down the assembly line in 91. Evo Maf/Dejon intake, custom FMIC, 3" exhaust with CAT and magnaflow muffler, v3 E85. That's it.