I never even wanted to mention A-Spec in this thread (obviously), but since you brought it up, why don't you compare to there regular pricing on the GT35R kits (that is if we're comparing)? When you do that, the pricing seems about right doesn't it? I think the fact that I'm charging more for fabricating a twin manifold shouldn't concern you at all. Fact is it's alot harder to fab a twin manifold, otherwise you'd see more of them around which I don't. What you should be concerned about is my pricing compared to other twin turbo setups. Comparing prices on twin turbo kits to single turbo kits is like comparing a Civic to an FD. Both have the same amount of metal, why does the FD cost more?

BTW, you're missing a few hundred bucks for build cost on the twins

 

I am not against the twins , In fact I think it would be awsome with my new configuration . But I dont like the GT28's for it , I would much prefer the GT28RS or the GT2871R , but these turbos are almost $1200 each. This is why one large single makes more sense to me right now, as for the size of the GT42, I have a TA51 with a 1.22 a/r exhaust and normal bearings, It would hit 12psi boost by 4500 rpm and up past 20psi by 6300 . I am sure the GT42R or the RS will be quite responsive with my semi pp.
If I can get either of the the smaller turbos at a better price I may just buy a manifold from you and put together my own twin kit.

 

Well, that's the thing with any turbo kit. One kit might be ok for one person when another person has a totally different view of it. These GT28R turbos will be good for someone that has a hp goal of say 450rwhp but still needs good drivability for the streets. I'm thinking now to just build a twin GT32 kit, but I just know people that can support this kind of power are pretty rare. Twin GT32 turbos will be pretty close to a 56 trim GT42. They also come in internal wastegate configuration so price would be just about the same as the twin GT28R if not cheaper. I'm gonna see what I can do about making a manifold that will fit any of the GT28R, GT28RS, and GT32 turbos.

 

Let me know what you come up with !!.

 

I think many fd owners would be very interested in a twin set-up since it would be great for daily street use and provide greater torque numbers on the low end side, however, I wil believe it when I see it, and until most of us see dyno numbers and/or time slips (trap speeds in particular) no one is really going to consider it...

 

the GT28RS turbo is a very nice turbo. its mostly used in an .86 a/r
with a max capacity of ~330rwhp. The drift scene raves about instant spool up of ~1bar by 3k rpms on an SR20DET

paired up they will be incredible because of the boost response and 500rwhp+ capability.

 

Just a thought. With a smaller turbo you need less flow to spin it up, but you have less flow. Inertia follows a square law with turbine radius, so far so good.

BUT, with half the flow to each turbo, the gas velocity is 1/4 than it would be with a single. Unless you can do clever things with the manifold design to get the flow back up to speed you often end up losing more than you gain. I would like to see it work, but the laws of thermodynamics are stacked against you a little with this one.

 

Hey John, I dropped you a PM a couple days ago about buying some manderal bends.....but I never got a response back. Just wanted you to know that I found some.

Sorry for being so off topic, but is anyone else having trouble with the PM system? My little task bar says that I have one unread message, but once I click on the link, there is'nt any recent messages.

CJ (bump)

 

Bill,
Could you explain this a little more. You have 2 combustion chambers, 2 exhaust ports into 2 exhaust primaries merging into 1 flange for a single turbo. Runners are generally same diameter begining to end.

With 2 turbos you could have 2 individual primaries feeding two seperate turbos or two split primaries feeding both turbos simultanousely. The later is certainly a design nightmare. Two individual runners with a small diameter should keep velocity high, shouldn't they?

CW

 

New year hangover making it difficult to explain in simple terms, but I'll try and dig out something out from my notes without going too deep into the equations.

 

Garrett Twins?

lots of theory on the forums.

i thought i might speak from experience.

i have 2200 miles on my twin garrett setup that i engineered, built and am in the process of tuning/evaluating.

i hear lots of posts from people on the forum about building/selling twins.... then they just disappear. i know of 3 people besides myself that have actually built and run twins. Kevin Wyum, who initially got me interested a few years ago, Igy from Okinawa who built a set of LARGE t04s that came on at 6000 and Marvin from sweden who ran a 123 mph 1/4 mile last summer on his first outing w his early stage tuned, modestly sized turbosystem, running 13 psi.

there are certain aspects of the discrete twin setup that i like. mine is different than any twin i have seen... maybe it is better, maybe not. if i hadn't had engine builder problems... 3 1/2 motors this summer.... all sealing related, i would have been lots further down the evaluation trail. i will be back on the road when the snow clears in march w 2 pre turbo loggable egts, loggable exhaust manifold pressure w my own built motors.

my turbos make 84 pounds per minute at 1.2 bar and spool at 2400 rpm. when it is fully evaluated i will release further details.

until then i will be building a few motors and studying the 2200 miles of logs i have from this summer.

and enjoying all the theorizing on the forum as to why they don't work.

howard coleman

 

I never said they wouldn't work, just that the thermodynamics is against you.

Having said that, some of the single turbo manifolds I have seen are so inefficient from a flow perspective that any gains in the technique will be instantly lost.