so i have a cosmo front clip with a blown three rotor in it. i wanted to do a swap in my fd but, i dont have the cash right now, but i was wondering if the twins off the three rotor are bigger, or if they are the same turbos from the rx. and if theyuse the same flange as the original twins from my rx. any info would be usuefull. cuz i have a nice intercooler, oil cooler and turbos that are all in the front clip and i would love to install them in the car. thanks

 

As I recall the 20b twins are asymmetrical. The fd twins use two ht12 cartridges and the 20b twins use one ht12 and on ht15. Hearsay though. I know theyre bigger. I severely doubt they fit.

 

The 20B turbos are smaller and not as efficient as the FD turbos (they didn't need to be with the 3-rotor).

 

alright u guys answered that one for me, thanks a bunch...

 

Mahjik they were more than efficient for how the 20b twins where designed. Though they were small, the small seq twins spooled extremely fast to allow the heavier auto Cosmo to make 300 ft lbs below 2.5k rpm's. They were more than enough for what the Cosmo was engineered for and it's automatic rpm range however, I know were not talking Cosmo here but a more customized project in a much lighter car. Remember David Hayes Pettit Banzai 20b Fd set-up? He ran his non seg twins on his 20b and made 374 rwhp and 340 ft lbs at only 8 psi. There's not one person on this entire forum that can convince me that this is un-efficient. Look at the dyno chart:



Anyways 9320bfd since your just starting out with the project, using the stock 20b twins has it's advantages. For one they come with the engine. Just buy or fab a down pipe. Using them is a great way to build-up the project. Most people here believe if you go 20b, go all out the first time(not me). That's why it gets so expensive. Use and modifiy what you already have, then build up from there as funds allow. You will save a ton of money this way.

 

I would suggest talking to Bryan at BNR. He has made the comment to several peopel who wanted him to rebuild sets for their projects.

 

True but those people are in search for higher hp levels than what the twins were designed for. This is why people claim they are in-efficient. My main point is those twins are making a ton of hp and torque with very low boost which leads to less engine stress and longer term reliability.

 

i am also interested in this

 

Yes, there are different perspectives for "efficiency". I was relating them to the FD turbos (as I got the impression the poster was wanting to use the turbos in his FD before his 20b could be rebuilt and ready to go) and I'm Bryan was talking about over all total power potential.

 

The 20b primary is larger, the secondary seems the same but the housings are different. No way the turbine housings would bolt onto a 2 rotor manifold.

 

See that's what I thought. My primary turbo on my 20b looks larger than the Fd's. So is it an Ht-15?

Sure looks larger in this comparison pic from the Alamo Rotary web page. 20b on top!