venom858

im confused here. some guy was posting about all the stuff he did to his rx7 and someone asked him if it was single turbo and he said "no not yet " i didn't think it would be better to have single, am i mistaken? maybe i just read the thread wrong but i cant go look at it cuz the site is too busy. anyway if it is better to have a single turbo can someone tell me why?

thanks

cash money

yeah it always sounds better to have 2 turbos instead of one, but one big turbo is capaple to make way more power than the stock sequential turbo's, and with alot less complication under the hood.

they make some upgaded twin turbo sets, some are "upgraded" versions of the stock twins, which don't preform as good as a single and have been troublesome to somep people, and there are some huge twins like the hks ones, but the kits are only in japan and are expensive *** hell.

you can really meet any realistic hp goal with a single turbo kit

i hope i answered your question

Crackers

The reason the twin turbo was designed for the Fd's and Supras was it was made sequential.. Witch means there is a Small primary turbo and a Seconday Larger turbo..

The Small Primary turbo spools [Spins up alot faster because of its small size] and creates boost around the 2500mark.. this turbo then runs untill around the 4000 mark where then the larger primary turbo is getting enough pressure built up to spin and create boost its self witch allows it create more boost then the Smaller turbo..

With a Single Big turbo you can get alot more boost at a constant rate then the twin turbo can but problem is you loose the Low rpm boost ability of the twin turbo.
Another thing is it doesn't have a Boost spike like the twins does when they switch between the primary and the seconday.

It's all presonal preffrence as I like the twin turbo because of its quick spool up and I don't need 20psi of boost any ways so I wont worry about getting a big turbo.. Well, I will eventuly due to the stupid problems mazda has with thier turbo system.. Ohh and the Single turbos eliminats alot of head aches caused by the sequential tiwns on the FDS.

Ohh and some people have installed Twin Big turbos basicly is the same consept of the Single turbo but with two big ones not like the Fd's seqential.

rynberg

Actually, in the FD's case, both turbos are the same size and both continue to work once the second one kicks in. To me, the twin turbo setup is awesome, as it provides very little turbo-lag and has a strong powerband from just over 2500 rpm to 7000 rpm. The only way I see myself going single one day is if the unreliability of the stock twins finally drives me to it. Mine have been good so far.....(all praise the FD gods, may your turbos, apex seals, and coolant seals last forever)

Ef-Dee

Anybody have the pics of the engine with both turbos in there? cause I thought there was a small and larger turbo in the engine...

JoeD

both primary and secondary turbos are the same size. why do people thik the secondary is larger??

GoRacer

iTrader: (2)

The smog pump was gone and normaly you see that removed because the singles don't use it but it had two intakes.

The twins are two mini turbos so there is no delay (lag time) and they spool at a lower rpm. The sequential is so there is a smooth climb in boost to make it streetable. A big single gives you a whiplash like kick/feel.

It would make more sense to me if the 2nd turbo was bigger but I beleive they are the same size and are actually housed in one unit.

This is how I understand it but there's guys on here that know it better than me.

maxcooper

I have two sets of turbos sitting around (one broken, the other is not for sale) and I can tell you that they are the same size. I have heard that the turbines are slightly different, but the basic dimensions are the same. They are both Hitachi HT-12 turbos.

They are staged so that the exhaust can spool one little turbo up quickly, eliminating low end lag, and then the second turbo is brought online when the first one starts to run out of breath. The boost level should rise to 10 psi by 3000 RPM, then there is a little dip to 8 psi at the 4500 RPM transition, and then the boost should recover to 10 psi by 5000 RPM or so and trail off to 8 psi by redline. The first three parts of that boost curve are often given as a tiplet of numbers like 10-8-10. That is how it was designed to work, but there is a huge amount of variability out there. It is not uncommon for turbos to boost 12-8-9 or 10-6-9 or 12-9-11, etc. Don't be alarmed if your system does not have the exact boost numbers I described, it is normal to be a little off.

The Cosmo 20B had a sequential setup with an HT-12 and a larger HT-15 turbo working together.

-Max

Ef-Dee

How's boost on the automatic then?

maxcooper

It is the same as it is on the manual. I am not sure I understand your question.

-Max

Ef-Dee

Since automatic shifts gears at lower RPM's, I would think high-end boost can't be achieved...

rynberg

I have wondered that too, because if you look at the specs, the auto makes it's max horsepower at a lower rpm than the manual. There must be some differences in the turbo setup. Either that or the auto is getting cut off early and not making 255....

GoRacer

iTrader: (2)

Although there is a "hold" button to delay the shift and you would have a wanna-be triptronic like a Porsche.

If you look at the dyno on a stock 7, you loose power after 6.5k rpm ( i think that's right) anyhow. Autos normaly shift from 3.5k to 5.5k but you can use the hold button to go to 6.5k.

Crackers

Well, I'm sorry for being wrong about the Size diffrence you majisty *******.

Dude, why don't you stop being so prestegious and learn people make mistakes. you are no better then the next person who owns an FD.

GoRacer

iTrader: (2)

Although there is a "hold" button to delay the shift and you would have a wanna-be triptronic like a Porsche.

If you look at the dyno on a stock 7, you loose power after 6.5k rpm ( i think that's right) anyhow. Autos normaly shift from 3.5k to 5.5k but you can use the hold button to go to 6.5k.

Sloraxe

My auto is all stock and practically breaks your neck shifting from first to second its so damn fast, it goes to redline through each gear and pulls strong all the way to about 110 where it tapers off slowly to 140 or so...don't go over that to often.

The only down side is it accelerates from zero at about the same speed as my mom's Camry wagon...that is tell the turbo kicks in at about 10-15MPH (or about 2500RPM)

Hold feature works good, sticking it into 2nd gear for flying in and out of traffic.

Power breaking for fast launches is alright, but I don't like putting that kind of pressure on my tranny...

Anyway I hear that our auto's get a straight 10-10-10 boost pattern and never dip to 8 like the MT.

MrFreeze

he doesnt have an FD

maxpesce

Same for mine on the shifts -
as to the boost, the auto has the same 10-8-10 patern, but does NOT drop any boost during the SHIFTS like a Manual will if you don't Power Shift. (ie keep the throttle open while shifting) Manuals will sometimes drop out of secondary turbo operation during a shift if you shift too slow and let the boost drop below 6psi.