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ClubRoadster.net Founder
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It doesn't look to be sequential, so how does it work and to what benefit?
 

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Discussion Starter #3
I've seen several inline 6 BMWs with similar twin turbo setups. Most naturally aspirated exhaust manifolds I've seen for BMW inline sixes are actually two 3-cylinder manifolds. Maybe they carried that design philosophy over to turbo manifold design for cost and ease of manufacturing? I've seen asymetric turbo installs (Saab, for example). My guess is that this Roadster twin-turbo was probably a project for fun rather than a quest for ultimate power or efficiency.
 
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FYI, I wrote to the owner/builder ([email protected]), here's his response:

"Dyno plot from this weekend:



10psi, manual boost control (bleeder type) greatly increasing spool time. I think I could have higher numbers with better intercooler piping (currently 2" pipes to old starion intercooler) and cat-back exhaust (currently ancient crush-bent 2.5 exhaust). Oh, more boost too. For some reason the car would make 3psi less on the dyno than on the road regardless of what I changed.

There are no real benefits for 2 smaller turbos on a miata. I would actually think it is worse than 1 properly sized turbo, mostly because of packaging issues. However, I do get rapid spool/low lag with the AEM EMS controlling boost (better than a GT28R?? I'll see soon, that's the next kit being made), and 2 turbos were less expensive than 1 fancy turbo.

Do, we do not sell this as a kit. This is on my personal car, and I wanted to see if I could do something different. Could I sell it as a kit? Yes probably. However I highly doubt anyone would want it for what I would charge seeing how there's no real performance benefit for the cost. I honestly have no idea what a "kit" would cost; before I got to the point of selling it in a box I would have to build a few more on the actual customer car, I charge $70/hr plus parts/material which I sell at my cost. Complete custom turbo kits normally end up around $5000-6000 (including electronics)."
 

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Mufasa in Training
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Ok...so it's just an experiment that proved what I was already suspecting (ie no real benefit relative to a single matched turbo). It is a nice job, I'll admit :)
 

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Faster spooling from 2 smaller turbos? Nice fabrication. :)
I guess that's the case but I have to admit that I don't fully understand why... :roll:

Smaller turbo...faster spool up
(I'm here with all of you up to thit point)

But since the turbos are not sequential we'll have
smaller amount of air moving the smaller turbos right?
 

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what about twiin scroll - anyone tried that yet?

reason I ask is I have a VF38 ready to rock (twin scroll, titanium turbine, ball bearing :) but just wondering if it'll be a noticeable improvement over the VJ20 on there now ...

umm.. sorry for the thread hijack ;)
 

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But since the turbos are not sequential we'll have
smaller amount of air moving the smaller turbos right?
Right, they're parallel. Essentially each turbo gets 900cc worth of exhaust driving it and only has to provide enough boost for 9psi.

Boogie, are you sure the Viper has a sequential setup? All of them I've seen package it as a parallel, one turbo per 5 cylinder bank.
 

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Btw I got the new Car & Driver that has two twin turbo supercars!
A Ford GT (yes they removed the SC!!!) with 800HP and a Lamborghini Gallardo with 700HP only :)
In both cases the turbos are parallel and in the Lambo case they were running only 4psi each!!!
...which requires small turbos which when they are driven by 5 cylinders (10 cyl total) and 2-2.5lit are having almost zero lag...
Very sweet design! =D>
 

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Boogie, are you sure the Viper has a sequential setup? All of them I've seen package it as a parallel, one turbo per 5 cylinder bank.
Im not sure how they were set up, My friend has seen the engine, I havent, but I was in my friend's Mustang when we raced the guy, just for fun. I know its hard for me to not sound like Im just making this stuff up. haha. This was over 5 years ago that I last saw the car, and now I dont live in the same area so who knows, maybe he doesnt even have the car anymore.

I know what your saying though, I dont see why one would want to do a sequential twin turbo on a V# engine, Its probably safe to assume they were parallel.
 
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