Twin Turbos on B18a1?

ASSISTANCE Forced Induction
1

I have boost in mind for the future of my car, and last night I would talking to a buddy of mine who threw out the idea of running two small turbos on about 4-5 lbs each instead of the conventional single turbo.

I want this thread to be an open discussion of twin turbo theory. Lets not start fights. I will begin by saying I’m still a noob, and I do not know everything.

I was thinking of having a custom manifold fabricated by a local shop in which cyl’s 1 & 2 went to turbo ‘a’ and 3 & 4 went to turbo ‘b’. Do I have this right? are they run in series or parallel? My assumption was series, but I could be wrong.

Also, would it be advantagous to run one exhuast or two? and how the hell would one hook up two turbos to one intercooler?

Has this been done before?

2

with enough money and time anything is possible. I don’t believe it would be cost effective though. you could run 10 psi on a single turbo with the proper compressor map for our engines and it would be just as effective.

3

it could work except i dont see if you could have the room for it. and the underhood temps would be crazy from having 2 of them.

but assuming you get those squared away and run two gt20s or 22s from garrett. it could work. and you would spool instantly.

but why not instead of running two turbos at the same time, why not run it like the audi BI-turbo setup.

what it is: one small gt25 that has the boost running into a bigger GT35+ and uses the small turbo to spool the big turbo even faster.

i am quite tempted to give it a shot but smog laws here in cali are a bitch. but i think ill grab a greddy sticker and give it a shot lol.

and to get the air from the turbo to theintercooler just have the two pipes meet up and go to the intercooler.

4

so the BI-turbo setup is run in parallel, small->big?

5

yes the smaller the turbo the faster the spool. shit you could run 4 of them if you could find the room and be under constant boost. but i think the best would be two small turbos, im looking up the different sizes from garrett right now to see what sizes youll need to run the best.
two GT12s would be the best but only good for a combined amount of 260hp
two GT15s would be good for aruond 300
two GT20s would be close to ideal for a 400HP setup

6

thanks. The idea would be crazy fast spooling, but my concern is more about the well-being of my b18a1 sporting stock internals.

I’d go w/the 12’s or 15’s then. I’m not looking to put down mega numbers.

7

yes the BI is using the small turbo to spool the big turbo. you would use something like a gt20 on all four cynilders to spool say a GT40 and after the big turbo spools, you would want a valve that bypasses the small turbo entirely.

id say go witht he two 15s and then you have room for upgrade and still have mega fast spooling.

and the numbers i gave are pushing the turbos to their limit.i believe around 15psi s the safe limit for a stock B18A assuming it was taken care of.

if i do go this route id only need 10 or 12 max.

8

huh. I will have to further research both possibilities. I’ve already pulled my A/c and soon I will lose my P/S. I’m also going to be ordering some slim fans, so hopefully that will give me enough room to work with. It’ll be a tight fit, no doubt. But this is a winter-long project. I won’t even to able to fund it for another month or so, but I want a god idea of what I’m doing before I do it.

9

to connect two turbos to one intercooler, all you need is a “Y” Pipe in the charge piping after the turbos and before the intercooler. pretty much turning two pipes into one.

twin turbo’s CAN be done a four cylinder, in theory. but would be the most part counter productive. yeah, for the most part on your theory of cylinders 1 and 2 into turbo A, and cyl. 3 and 4 go to turbo B is correct. as when cylinder 1 is at TDC, so is cylinder 4. i can’t remember the firing order off-hand, but i’m sure for a fact that its not 1-2-3-4 so you’d want to pair up the sets of cylinders in their respective firing order, to optimize flow to the turbos.

i’m open for the discussion, but in essence, it would be a waste of A LOT of money that most don’t have. it HAS BEEN DONE on drag cars, anyone remember that 4000hp drag integra? thats 1000hp per cylinder, thats nuckin futs.

space in the engine bay is also a big problem, as it has one of the more cramped engine bays in honda’s lineup. the new civic’s and rsx’s are a little more cramped, but they are packin the motors that we want (K’s) with NO ROOM to spare lol. they barely fit in there. fitting a much larger manifold setup, with TWO turbo’s and at least until it gets underneath the car TWO downpipes. we have enough problems fitting aftermarket exhaust manifolds and exhaust systems without scraping/hitting crossmembers, let alone two exhaust systems (at least until they are brought together with Y pipe)

anyway, theoretically its possible, but financially speaking, its not worth it. i’d go with single turbo any day of the week.

a setup like this could run in the 5 figure price range, when a single turbo setup, that will bring the same results (if not better), will run you about 2,000-5,000. thats less than HALF the price. its a nice idea to think outside the box and be different, but outside of doing it just to prove a point that it can be done, and being a show car, it would be practically useless.

blu’s 2 cents :wink:

10

thinking further on it, Idk how the hell one could fit two turbos in there with all the piping that will be going along with it…

11

get a civic radiator but that might not be enough cooling.

remove everything you can. and connect the pipes before they go under the car.

and if you can do it yourself then you wont be spending 5 figures but it will still be alot more money then a single. but in the search for throttle response the question is it worth it is one you have to answer yourself.

im gonna give it a shot pretty soon so ill start gathering parts and start peicing it together.

now that i research it a little more just go with a GT2554R

itll be ideal for your power goals and will spool quick.

12

yeah, I did the same research and came to the same conclusion. I don’t have the money to do a twin setup. It would be sick, but I think I’ll just go single.

The main reason I origionally wanted to do this (besides insane spool) was just to do something original, but inadiquate funding pwns me.

that or the gt2560r

eh, to keep the quick spool I’ll probably go with your origional suggestion…

I have plenty of research left to do, lol

13

if I’m not mistaken the bi turbo set up was done on a crx. There might have been a thread on honda tech from as long as 2-4 years ago that contained a write up with pics. If I recall correctly it was a crx with a b16a and the turbos were close together on the manifold and clocked in the same direction. Again this is going from memory off of a potentially 4 year old thread.

14

it can and has been done for a fairly ok price. just go to home made turbo and look up it members, a guy on there has an b16TT and it runs nicely. but to be honest with you build yourself a stout motor with the money you would be spending for two turbos and then throw a big single in there and you’ll deff be more pleased with the results

15

that would be Jeff Frank, the owner @ homemadeturbo.com. He did twin IHI turbos on a ghetto LS Vtec with compression like 11:1. His build was bottom dollar but the end results were decent. This included a custom manifold (runners 1&4 on turbo1, 2&3 on turbo2). He made it just in time for a hondatech meet and it was a big success. I remember the dyno results were a bit fuzzy since the wastegates didn’t act well together.

I can’t find the thread, their search engine is down or something, I’d have to look around for it later. About a month after it was built he decided to move on to the next project and put the TT setup on ebay for like around $1,000. He asked me to up the bid for him but I think the first winning buyer ended up flaking out. I thought it would have sold like mad.

Overall the kit was impressive. Expect to shell out some money for custom fabrication if you want one yourself.

16

Ive seen that thread. talk about a cramped engine bay :shock:

I would love to see some pics of the progrees if you decide to do it. i also agree that one turbo is realy all you need. but for the sake of originality, i say go for it.:up:

17

its hard to explain it but i figured it out now i justneed to figure out how to explain it. ill think about it some more at work and see if i can come up with anything.

18

aside from being the first to do it, Jeff said that it spooled extremely fast. On top of that it made a very unique sound. He has run dozens of turbos open downpipe and said that this one sounded different from the rest (more baffled and deeper I believe). He also had true dual exhaust (dumped back into one). The rest of the kids just like to Y off single exhaust for the dual exhaust look.

Up to you, but I think having to worry about one turbo is easier than worrying about two.

19

beau had the b16tt and whitey had the d16tt… might have been a d15, i forget. both cost almost nothing to do.

20

i am liking this idea, of a custom manifold holding both turbos. 2 on one side 2 on the other.

if the turbos are small enough it should fit fine. having the AC & PS removed that is, right 2 cylinders have the manifold pipes going towards the spot where the washer res. and PS res. are, and left side going to the spot infront of the distributor. have the downpipes coming down fromt he inside of both turbos into the front middle of the engine.

the only thing i cant really picture in my head is the intercooler piping route. but i will probably be kinda playing around all day with pen and paper on this.

if someone did do a setup like this it would look pretty sweet, may not prove to be the fastest but def. a good show points type of thing.