There is a problem with this analysis IMO. Most of these mods are a factor of desired POWER LEVEL, not turbo choice. Clutch, fuel delivery, twin power, wideband (optional), EGT (optional), midpipe, and Tune.... These have nothing to do with Single Vs Twin.

$70 for block offs
$150 custom piping
$200 difference in turbo cost
$200 odds and ends (maybe)
+ additional Labor

So all I see is $620 in cost difference between single and BNRs at the power range of 370 to 400 hp.

BNR's are not stock twins, they just bolt up like stock units.


You should really rethink your turbo choice and cast iron manifold. Going single does not always mean faster. You have to pick an appropriate setup. Pony up the $$ now and be stoked later :) or otherwise spend a little less dinero and be unsatisfied :(

so where's your wideband, EGT, clutch ,Twin power, Downpipe? Don't forget a MP if you steer away from T60-1 (which I strongly sugest)

that is exactly what i am saying ........if the bnrs were 1000-1500 dollars it would be a no brainer. but at 2350 plus mods......i see the single more apealing.

Ok I see what you are saying I guess I'm just stuck on the idea of "if you are going to do something, do it right."

anyone who goes single without a wideband and EGT, deserves that rebuild. CFM for single =/ CFM of twins.

The mods I listed are a must for a single 400 RWHP FD. A properly sized turbo for 400 RWHP is just going to suck at let's say 300. While BNR's at 300 will be a blast, and in the mean time he can upgrade accordingly and get to his target HP.

So yeah you are correct he can get that single and run low boost and be nowhere within the efficiency range. My GT35R just plain sucks at 10 psi (which I get at 3300 RPM). Shoot my old twins felt faster. Life begins at 12 psi with that guy.



It's your car, if you believe that setup you are choosing will yield you better results than the BNR's then go for it. BNR's are great turbos just because they fit like stock does not mean they are like stock.

I see your point about BNRs being better during the upgrade path from 300 to 400. But at 400hp, the EGT and WIdeband are a MUST for the BNRs also. Why would they be more necessary on a single?

Like I said earlier, the engine does not care what configuration your turbos are, it only cares about the amount of compressed air/fuel being forced into the chamber. All supporting mods, with the exception of the $600 list above, are needed for BOTH BNR and SINGLE.

In addition, at 400hp the BNRs are reaching their limits, certainly if you want to remain sequential. Then there are the usual benefits of a single: 1) less complexity 2) easier thermal management 3) clean engine bay

yah but that T60-1 will run out of steam before the BNR's do.

100% correct. No argument from me on that.

EGT and wideband are becasue of the CFM. Like I said it varies greatly from single to twins. It would be a terrible idea to configure and not monitor those parameters. So yeah he does not have to do it, should he? hell yeah. Even at lower boost levels. 10 psi on twins is not 10 psi on a single. Like I said it's all about CFM.

Oh yes you are preaching to the choir with this one :). I was contemplating BNR's but ultimately I went single. But I went all the way. Like I said do it right the first time and enjoy the car.

Cheaping out on parts hardly ever pays off with these cars. That single setup that he is planing to put together is going to yield lacking results and it certainly won't be better than BNR's.

Agreed.

I would either go with BNRs or make the leap to something like a t4 divided 35r. In fact, that is what I'm doing, except I am cutting some corners. I'm buying the turbo new (hate used turbos), but I'm piecing the rest of the kit together and may even use an ebay manifold. ;)

According to the rx7store t60-1 will make 400whp easy. Doesn't it? Either way i would probably rebuild and streetport my engine first hoping to get 330whp @14psi. then i will consider the single or bnr conversion.

i have heard some ok things about ebay manifold specially obx. for the price 160 dollars i would gamble on it. worst case scenario it breaks and you weld it. breaks again and you are out 160 bucks. but if it works you save at least 500 dollars.

really amazing how these same tired questions/responses come up literally hundreds of times over the years

Brits can be a crazy lot when they get an idea in their heads ;-) Dual single project from one of my other forums.

And it's fairly doable to reach 370+ whp (by American dyno numbers) on BNR's.. I'm pushing 325whp (add 15-18% for US comparable number) at 1.1bar with a stock ported engine and Sequential BNRs.

One thing the OP should keep in mind, if you are going to try to push larg(er) power numbers in the 7 than you need to upgrade more things than JUST the power adders... Horsepower numbers are just numbers if the rest of the car isn't in sync, and those numbers won't stay around if they aren't properly supported.

I registered, but i don't have permission to see the thread. Gimme some search terms and i'll have a look. A dual single project isn't that ground breaking, herblenny or mahjik runs a dual t04 IIRC. I'm talking about a stock configuration manifold.

Ah, reading comprehension owned me this morning it seems =P I thought... hell I don't know what I thought you were saying =P


The thread should be on the first page of the Engine/Performance section, titled "My New twin single project".