junt

I have read that these turbos spool at about the same speed, but what about at the top end. Which would you get more peak hp from?

maxcooper

From the reports of owners and probably some speculators, it sounds like the TO4E and RX6 offer similar spool-up, with the RX6 offering more HP up top.

However, the TO4E is rebuildable and the RX6 is not. This is important because if you throw an apex seal at the turbo, the costs for getting the car back on the road are quite different. The TO4E can be repaired and the RX6 needs to be replaced. I did have luck getting my RX6 turbine trimmed by TEC (the only place that would even look at it) to remove some apex seal damage. But you can probably only do that once if you are lucky, so the next time will probably require a new turbo.

-Max
93 base, w/RX6
http://www.maxcooper.com/rx7/my_car/index.html

vosko

iTrader: (4)

i'm assuming something happened to your engine max ??

junt

so what would it cost to replace the rx6 turbo vs. repairing the t04e?

spyfish007

rx6: replacement cost is like 1700
to4e: replacement cost is probably no more than 800 to 900 and individual parts being in the 100 to 250 range.

maxcooper

Yeah, it overboosted big time and I think I cracked a seal. It still starts and runs, but the idle is a bit lumpy and the power is down from what it was.

I'm going to get a new wastegate (I think the overboost was caused by it sticking) and get Mazdatrix to build me another motor. I've got to get it togther quickly so I can do some tuning and then run the Open Track Challenge. That's the plan anyway... we'll see how it all turns out.

-Max

TROYRUSSO

I too am curious, I have spoken with people that said the opposite, that the rx6 spooled up a little faster but the to4e being a larger turbo had more hp potential. I thought the rx6 had a max hp of 390rwhp.

However, Max is much more knowlegable than I am.
I will look for more posts.

maxcooper

The highest RWHP I have seen for the TO4E is 393 on carcrazy's car. Chuek has gotten well over 400 RWHP on his RX6 running similar boost. I don't know much about their relative spool-up speeds.

I am sure that others have numbers to report. Consider my report here to be the "straw man" numbers that you can post against. What RWHP do these turbos really support?

-Max

MeLoco

You should be able to get 400+ from the RX-6 Apexi specs are as follows:

RX-6 TCW76 P27 BB Turbo supports 450HP
full stainless manifold downpipe and wastegate dumppipe
Apex racing wastegate
Intake
intercooler plumbing for stock location.

This turbo is really really nice, very durable,It's not that the turbo can't be rebuilt it's that you would have to get Apexi to rebuild it (big expensive headache).It is very responsive almost like the stock twins, most people run it at 15lbs. Feels great at 18lbs.

Seeing 400+rwhp shouldn't be a problem with some good porting and what not.

maxcooper

That's true -- it is just that the RX6 can't be rebuilt in the U.S., not that it can't be rebuilt anywhere. I think that there are several places that can rebuild them in Japan, it is just that there are no U.S. rebuilders that can get parts from IHI to service the turbo. Like turbine wheels for instance...

I am not exactly sure what A'PEXi means by 450 RWHP, but I suspect that is somewhere near the RWHP limit for the RX6. The RX6B is supposed to have a slightly larger turbine housing, I think, which should support more peak HP but probably at the expense of some spool-up. The turbine housing on the RX6 does not look very large, and I suspect it is the limiting factor. In some ways, the RX6 doesn't seem like it would be a very good turbo for a rotary, since rotaries are quite sensitive to backpressure and exhaust flow issues. However, in practice it seems to work pretty well, especially if your goals are drivability and throttle response (quick spool-up) rather than peak HP. Certainly there are many turbos that make more peak HP, but I suspect that the RX6 is likely to be the fastest spooling turbo kit available. I can attest to the fact that it spools very quickly and builds boost from low RPM. I can't imagine anyone complaining about those characteristics on an RX6-equipped car.

I have the RX6, but I haven't done a thorough dyno sheet comparison of low-end or peak power against the TO4E. I am mostly just regurgitating the reports I have heard, including the dyno numbers that stick out in my mind. If someone else has dyno numbers to post, I am all eyes -- let's see them.

-Max

spyfish007

Outside of Chuck's Apex I am yet to see a dyno sheet above 400 for the Apex. I have seen the TO4 kits spool just as fast as the Apex kit on the dynos I have ... just reporting from the dyno sheets I have seen either in person or on the internet. I have spreadsheet but I don't really want to release it ... sorry.

Oh yeah ... I have TO4(s) getting just as much HP per mods as the RX6. I have always heard the wheel is what is so small on the Apex turbo ... yet to check out the turbo off car.

Cheuk in Seoul

I have to agree... the turbine is small for a RX-7. I'm sure this is what limits the output of this turbo.

The impression I get from the Japanese neighborhood tuners is that they use kits direct from Greddy / HKS / APEXi... very few of the tuners build their own kits. The turbo kits for the FD seem to be divided into street turbos and track turbos. I feel that the RX6 is the best of the "street" turbo kits... that is for cars using pump fuel and 15-18 psi. The larger turbos T78, T88, T51.... seem to be limited to their show cars and track cars... although I think that many of these "track" turbos are streetable. And some of the recent US kits seem very good... I am especially impressed with the T04 E + S kits.

I believe that 450 RWHP is about the max you can expect to see out of this turbo... any more and I think that the turbo would have to be driven outside of its effeciency range. I haven't tested the car at more than 15 psi but I bet I'm pretty close to 450

maxcooper

Dyno sheets don't display some of the information about spool-up. They show what boost you'll get by planting your foot and revving through the tach. But they fail to show how quickly boost will rise if you are already at 4500 RPM and add some throttle, like on a corner exit. I am not sure if there would be a significant difference there or not, but I am inclined to believe that a BB turbo should spool up a little faster.

-Max

vosko

iTrader: (4)

i'll let you know how streetable my greddy T78 is very soon. my choices were between the T04S and T78. i actually purchased a T04S but never got it so i cancelled the order and got the T78 which is a great kit along with my greddy 3row fmic my car is a street car but i don't think it will be driven on the street much

spyfish007

Max: Good point you made: the difference between lag and spool up. Lag is probably underrated especially if you consider the fun factor of a fast spooling turbo but the only way to tell outside of datalogging is the trusty butt dyno! This is usually why I just talk in spool up.

XSPOWER

The T04e easily out responds the RX-6 under ANY condition. Likewise, the RX-6 will out power the T04e under ANY condition. However, for the 10hp advantage with the RX-6, I think anybody that has driven cars with either turbo can tell you that the T04e is a hell of a lot funner to drive. You can expect 360-370 on a stock engine with a T04E and 370-380 on a stock engine with an RX-6. The HP levels are with both turbos at 1.0kg/cm2.

Despite the horsepower numbers, you guys should check out the backpressure readings on the RX-6. They're HIGH. The compressor section on the RX-6 is nice and healthy. Unfortunately, the RX-6 turbine is just way too small for a rotary. Also, nobody rebuilds RX-6's here in the states. There's barely any support in Japan for the RX-6. That's why Apex sells rotating assemblies.

sparkie

I like your SE37K rims. Got a question? Are those actually black or bronze? If black, I guess that's special color, right?

TIA,

maxcooper

Thanks. They are black, which was a standard color, but I think I got one of the last black sets and now it is a special order color.

-Max

newRX7fan

iTrader: (1)

Comparisons like these need to have the psi along with the HP. Comparing (for example) one turbo @ 15psi vs another turbo @ 18psi doesn't tell you a whole lot about the turbos. Also whether or not a midpipe is being used.

That said, Max and I should be a good comparison of the RX6 and the T04E once we get our cars together and tuned. We'll both have ported engines (although by different shops) and I think we'll both be at the same boost, like 15-ish.

Max, do you use a midpipe?

maxcooper

Yes, I do have a midpipe. You can read the complete list of mods (but slightly outdated as of Feb 11) for my car here:
http://www.maxcooper.com/rx7/my_car/index.html

I think that XSPOWER's comments are likely to represent the most informed opinion so far. XS tuned my RX6 car, and surely they have had a few of their TO4E kit cars on their dyno. Granted, it is XS's turbo kit, but they also sell the A'PEXi kit, and any informed comments from other people on one turbo or the other are likely to come from someone that owns that turbo and thus has an interest in presenting it in a positive light. I am happy with my RX6, but if I had to do it again I might get an XS kit because the turbo is rebuildable, the XS kit costs less, and seems to offer very similar performance.

-Max

Mr. Stock

I read Maxcooper and XSpower's comments with great interest as I am about to go to a single turbo set up. I was initially set on going with the Apex'i RX6 turbo but I wonder if T04E may be a better set up for my needs.
What I want is about 400 RWHP and MINIMAL lag.
Which is better for this application, RX6 or T04E?
I wish I could drive a car set up with each.

LUV94RX7

iTrader: (3)

My gut feel is the XS T04e kit. XS knows their stuff.

Ken 57 years young,
'94 white, pep, red leather,
mods: Street port and polished stage II, upgraded coolant seals,
Hurley 3mm racing apex seals, XS T04E Turbo Kit,
GReddy SMIC, Pettit ss resonated MP, Pettit ss cat-back,
RP Racing fuel pump, Aquamist 2s water injection kit,
under pulley kit(no air pump), Pettit short shifter kit, boost gauge,
AEM EMS, 3-bar MAP Sensor, Profec B(12-2?psi), 1600cc injectors,
LaBreck bushings, Evans coolant.
<http://nopistons.com/luv94rx7.html>

Mr. Stock

LUV94RX7,

I was going to e-mail on the "big" list about your T04E.

Have you had a chance to drive your car yet with the T04E installed? If so, what is your impression of the turbo lag, copmapred to stock and other single turbo cars that you may have had a chance to drive?
And what about power output from the turbo? I assume that KD rotary will tune the set up for you on their dyno.

vosko

iTrader: (4)

another nice thing about the T04E setup is you can get a broad range of turbos if you are so inclined. apexi only has two RX6 turbos the RX6 and RX6B i think. i was originally going to run a T04S on my car but couldn't get the kit in time so i went with a greddy T78 kit that was in stock.

LUV94RX7

iTrader: (3)

My car has been at KD Rotary for one year. It would be best if you ask Dave about the XS T04e kit. I'm waiting for the AEM EMS to finish my car. Probably will be able to fly out and pick it up in a couple of months.

KDR Performance Inc.
243 Industrial Drive
Nazareth, PA 18064
PH: 610.614.1214
FX: 610.614.1255