ok guess this is something im trying to find out. Ive been told by people that twins are better or a small single is better thn twins. which is it? cause id like to keep the twins and maybe get some 99 spec twins, but im trying to get some info first, Any help would be great!

 

I'd find it hard to believe that the stock twins could keep up with the Apex single. I've heard it surpasses the twins at a very low rpm value like around 2k. Even a 60-1 might not be too bad. For road racing i'd definitely think a single would be better, and i would even think for autocrossing, but on a really tight course it might be debateable.
just my $0.02

 

getting a single turbo would also help with the heat problems caused by the stock twin turbos.
And yeah obviously a big single turbo will kill the very very small twin turbos. Are you talking about lag or performance on a track only or what? It just depends what you are going to do with the car. Also think about how long the twins would last you with tons of boost and running a 11.5 in the 1/4 mile compared to a single turbo doing the same.

Don't get a single turbo because I will be jealous and have one more rx7 better than mine.

SnooK

 

Apexi turbo is not rebuildable so keep that in mind if you decide to get a smaller single. I would go with the XS T04E or T04S for autox. There is a lot of solutions out there and if you have a single turbo question post in that forum because those guys can help you a lot better.

 

I'd really doubt that a single could spool as fast as the stock twin as low as 2k rpm.

I auto-x a lot, the quick spooling first turbo really helps out coming out of tight corners vs. the small single on my old TII (open intake and exhaust). The twins just have more bottom end sooner with a main cat on (port size and IC size doesn't matter as much at lower flows).

The spool time won't show up on any dyno plots. Everyone try a time to boost situation. Floor the car at a certain rpm and see how long it takes the boost to build.

Singles are better for road racing I'm sure, I would question it for auto-xing. This is dependant on course design, a fast course the single might do better, tight courses the twins might do better.

Jeff

 

Even the stock sequentials at 13 PSI on primary are low on torque compared to a V-8 (primarily why Z-06s are spanking FDs in SS now). I've driven my car and a C-5 back to back on the same course- my car was a dog in comparison coming out of low RPM 2nd gear corners. ANY single which is laggier than the stock seqs. (probably all of them, eh?) will perform worse.

Having said that, I'm probably going to go single anyway next season...

Gene
www.purplemantis.com

 

well i was just thinking back to the RE video where he redoes that fc and i remember it having a single turbo (not sure what kinda) but that was used for road racing and i liked. But i wonder if it could compete in a autox and do fairly well. i know the fd is a great race car, but can a fc become a great race car. i know it is already one but im talking an outstanding beast?

 

Well I haven't driven a C5 or Z06 but I have ridden in them on the same course. Your 100% correct, we have NO torque compared to those cars coming out of tight 2nd gear corners.

Riding in one of those cars makes me think I need to have one to be competitive, then a well driven Miata or MR2 non-turbo comes in .5 sec (or closer!) behind both of us.

Jeff

 

One of the forum members recently posted that after switching to the APEX kit he compared dyno graphs from his twin settup and then with the APEX with all the same mods and similar conditions and that The Power of the APEX had eclipsed the power produced by the stock twins by like 2300 or 2400 rpm, which he was shocked by as was I. I realize this isn't full blown proof and that torque plays a big role too, and the conditions could've been somewhat different, etc etc. But the apex is pretty small by single standards and is also ball bearing so it spools incredibly quickly. I believe the same forum member noted that throttle response was immediate. I think a better guess would be more like 2500 or 2600, so i guess 2k rpm was a little off, but not too far

-Rob

 

I have a apex single turbo, it definitly boosts faster than my stock twins. The ball bearing is the key. I have full boost at 2800 RPM were as my stock second turbo doesn't kick in till 4500. I use this setup and I'm the fasted at auto-xing in my area, allong with road racing. Though a bigger single turbo would be better for road course but worst for autocrossing.

 

Depends on what type of stock twins dyno plot your looking at right? A completely stock twin set-up compared to a single with open exhaust, intake a larger IC? A fully modded car with stock twins vs the single turbo with a cat on it?

Also my point was that dyno plots can't and don't pick up the transient boost response. That is the time it takes the turbo to spool at a given rpm. Run the car at a constant speed at a particular rpm, floor it and measure the time it takes the boost to build.

Jeff

 

i don't have an apex, nor would i ever buy one, just thought i'd try and offer some info i had read on the single turbo forum. I'm sure the apex doesn't spool as quick as the stock twins, but i bet its darn close, close enough that the APEX would be a better choice for most autocrosses.

BTW- i have a T-78 on my car with all kinds of lag and don't autocross for that very reason. I don't have the apex single and can't comment on it personally, i was just trying to help out!

-Rob