Is it worth upgrading the twins or go single?
 

Hi all,

I'm rebuilding my engine later this year and at the same point if I have the cash I either want to upgrade the twins or go single (my second turbo is on it's way out).

Does anyone have any thoughts on the pros and cons? I'm not up for building an all-out monster, I just want to get a quick street car that'll be nice and quick.

I don't think anyone in the UK seems to upgrade the twins, they always go single so just after some international opinion as well :)

Cheers.

Paul.

To properly run a single, you need a LOT to go along with it. Fuel system, intercooler, exhaust, etc. etc. etc. There can be a lot of hidden cost there.

People have been making 300-350 hp EASY out of the stock twins for ages.

Personally, I'd get a good set of used twins, get the car running, and have fun. Spend the money you would put into the turbo on other things the car might want or need.

Dale

Do some reading here: https://www.rx7club.com/forumdisplay...aysprune=&f=23

I'm sure you are well aware the costs of going single ie...Injectors, fuel pump, ect.....but the big thing I had to get use to was the turbo lag. I'm running a PT63, its honestly not that bad, but making the jump to twins to single I really felt the difference. I recommend you get a ball bearing single

But putting lag aside, when the PT63 kicks in, its FAST as HELL!!!!

i would upgrate the twins lol but thats just me because i love them so much

If you are already running over 300RWHP with the twins, then you should already have some of the mods needed to run a single such as: better fuel pump, IC, radiator, 1200c secondary injectors and an ignition amp.

I already had all of this stuff.
Thus when I went from non-seq twins to the A-Spec GT35R kit, the only real thing I had to buy where bigger (1600) secondary injectors. But I did that later on when I started running 15.5PSI boost instead of 14psi boost.

I did have to do a little extra engineering because I wanted to be able to pass emmisions here in Texas.

With the proper single, you will not have any lag to speak of. Sure you may say it spools slower down low as compared to above but then the down low power will still be greater than when you were stock, so there is no real complaint.

The GT35R spools very quickly.

Cheers everyone :) I think I may stick with the twins for the time being and upgrade all the bits over time then I'll be ready to go single. Getting a street port done when I rebuild the engine too so that'll give a bit more power.

Thanks again!

killswitch,,, hi there fellow UK rx7 owner,,, i was thinking the same sort of thing as u (single or twins),,, i beleive if u plan on running it on the streets and want drivability, twins are the way forward,,,,,,, but when u ready for more power have a look at the BNR stage 3 twins,,, i read so many good things about them,,,, (still supposed to produce amazing spool up time and have the ability to push more air than the smaller stock twins,,, so they can produce just over 400BHP),,, thats what im looking at because i dont want big silly lag!

hi tiger18! yeha i looked at the BNR twins but they looked rather expensive as you have to send your turbos and y-pipe to them.

Well, he prefers that you do, but when i talked with the guy who runs the shop he said that he may be able to scare up a set of used turbos and rework them. It'll cost a little bit more, but that way you don't have to have your car down for however long it takes him to do it. ;)

If say your running stock twins with stock fueling(obviously this would be changed to larger injectors), street port engine with full decat @ 320hp atw what would the gains be if you swapped the stock twins for 99 spec twins?

Single makes problem diagnosis a snap.

Personally, I went from the stock twins to a Greddy t-88. There is a lot of lag but when I hit 4700rpm it's scary fast! Plus it's always nice to beat vipers :wink:

If you still want a good car for both road and drag get a gt35r, t-78, or a 500r, either way there is many cost factors to consider.

Myself, I wanted a big turbo and anything smaller then a t-88 just would not cut it for me. So do lots of research and decide what will be the best option for your needs!

Very little if any, they spool a little faster. With my FMIC there is plenty of lag under 3500, well over a second. I personally would go single now, way to many things to go wrong. I would also hope that you would be doing better then 320 with the above setup more like 340-370hp

I just drove the mazdaspeed 6 a few weeks ago and that had no lag at all. It also felt pretty slow.

true that, It goes from a big mess to simple and clean. I run the to4 116a/r and I see pretty decent spool. i don't miss the twins at all. mine were spilling oil out of the rear turbo at 130'000 miles and it was just time to get rid of that ugly rats nest under the manifold as well. :)

that's what I'm doing....BNR Stage 2s this year with all the fuel mods (a nice chuck of $$ if you do it right), then maybe single next year when I get bored with the twins or die in a high speed wreck before then :)

I think I'm going to be doing lots of research to decide if I can justify the costs of a single. I want a fast street car more than a fast drag car so low lag is important :) I shall see.

I was considering the BNR Stage III until I talked to the guy there, I believe his name was Brian, he runs a single on his 3rd gen. That said it all for me.

It doesn't really say anything. Everyone has different priorities and preferences.

:iwstupid:

Yeah, what he said... ;)

I really all comes down to personal taste and what is best for you. Personally, i'd like a small single, but at 1/2 the price, i'm considering the upgraded twins. Very similar power with less lag, but you still have the first to second turbo transition and the rat's nest. I'd hate a large single turbo more than anything else, but, like someone else said, nothing less than that would satisfy them. It's all a trade off and comes down to each person's preference coupled with their budget. For right now i'm very happy with my stock twins...but we all want more power sooner or later. ;)

I know it's been around before but just in case it was missed, I have a writeup of all I did when installing my "small" single T.
http://www.negative-camber.org/crispyrx7/gt35rpage1.htm
Most folks fail to list *everything* needed to do a single install and the total costs for the conversion can be misleading.
As for how much power you can make it's a tossup. I local friend - who might chime in - has a solid 360rwhp at 14.5psi on a set of '99 twins with a ported motor IIRC.
HTH,
Crispy

That is funny. I have had 3 sets of twins on my car and about 3 singles. My car has been a test dummy for every application. I would run twins on my car, but parts are scarce and have been that way since I have been doing turbos for 300Z's. I don't want to miss out on a sell b/c I decided to put the upgraded twins back on my car. My FD was tuned for the turbo thats on it and I don't have time to mess with it. With twins on my car, it realed in bikes like fish on the interstate :D. I am contemplating putting a 3 rotor engine in the car now since it needs to come apart b/c of the wife backing into the rear 1/4. Time for painting.

You can also say that about my 2nd gen. It didn't have a hybrid for a long while. It had a HKS exhaust manifold and a T4 turbo on it. I still sold hybrids for the 2nd gens and have a lot of support. Now I run a hybrid and it is so drivable and quiet, it feels like a new car even with 200K miles.

I am not saying that hybrids is right for every application. Sometimes a hybrid upgrade just won't cut it. I market to those that need stock apearing upgrades that will pass smog and visual inspections. Also road racers and autocrossers need the benifit of an upgraded turbo but retain stock appearance.

Take it easy.
Bryan@BNR
205 640 1193

upgraded twins are good if u want to make your 7 alittle quicker. but if u want to roll with the big dogs u need a single and alot of boost. thats the way i see it.

Wow. Is it just me or is the contrast between those last two posts and the kind of people who make them absolutely hilarious? Personally, i'd rather be associated with the former. ;)

I'd rather be a good driver in a slower car than the other way around. Most of my money goes to track driving schools instead of 'mods'. Not that there's anything wrong with mods, but when it comes down to it i'd rather be known as a good driver than that guy with the freaking fast car. Cause when you sell or wreck the car, who are you then? Just another loser. ;) (Not saying that anybody here is...but that seems to be the two major classifications of people i meet and come across. I think you all know what i mean.)

Sorry for the hijack. Now back to the topic...

I'll probably be getting in touch with you early next year about those upgraded twins, Bryan. Keep it up, man, and thanks for all the work you're doing for these cars.

one vote for single.....

some people track their cars and some just want a fast car. who cares?