to4s vs gt35r
 

im trying to determine the lag of the to4s with 60-1 wheel, p-trim, 1.00 a/r and the gt35r with a 1.06 a/r (i think thats right?)....what rpm range would you migh see full boost at 15-16 psi???

also what has more potential at 15 psi...im trying to compare these turbos...they are what i want but im just trying to educate myself...thnx
sniffle

its rather tough to talk about the "lag" your gonna feel between 2 similar sized turbos due to the fact every car is different and each will have a different set-up also.... if we had the luxury of switching turbos on the same car, life would be grand :) try searching both turbos and see how the owners comment about the response and feel of the turbos and see if you can grab some feedback that way
both are great turbos, personally i like the GT dual ball bearing turbos :D


good luck!

To4s
 

I don't know about the GT35R having never seen one in action, but the TO4S (or TSO4) depending upon whos speaking I have seen.

The JN's call the to4s on a rotary a DoKan Turbo becasue the lag is pretty bad, but once it spools, stand by for some fun (ass end all over the place).

my friend got his car tuned locally (I think it ws a poor job) he had HKS cast mani, TO4s and an powerFC computer, it seemed to spool pretty late in the game like right around 4K (once again tuning plays a major role).

hope that helps ya.

kenn

hope that helps a little

I have a T04S with 1.00, P trim, 60-1 and it can make 15 PSI at 3500 rpm.

I like to cruise at around 3000 RPM, and from there, the lag is very small. Sure, if you drive around at 2000 RPM, it will lag - but who the hell drives a single turbo at 2000?

wargasm,
what supporting mods you have on yours to make you spool so much sooner then all the others i have searched for....i have see a number of 4k to 4.5k of full boost, but in yours you are significantly lower.....i like the to4s's potential and you seem to have the best experiance with this turbo..and i do like the gt35r...bc i hear great stories except that the top end suffers alittle...someone plz help im completely lost....

or is it that the to4s that you have is different then XS's kit to4s???

We should always be clear here when referring to the "XS" T04S. There is a place called "XS Power" that makes kits which pretty much everyone says suck. There is another place called "XS Engineering" that makes kits that work much better (but I think a few people still had some complaints). Mine is the XS Engineering kit.

Here are some links showing you what I've done:

Dyno - http://www.zeroglabs.com/rx7/dynoresults.htm
Mods - http://www.zeroglabs.com/rx7/mods.htm
Porting - http://www.zeroglabs.com/rx7/porting.htm
Kit pics - http://www.zeroglabs.com/rx7/newturbo.htm

To make 15 at 3500, that would probably be a 3rd, 4th, or 5th gear pull to load up the turbo. In first and second gears, the turbo spools really fast, and the engine is accelerating so fast that I am not sure if I can get 15 psi by 3500 or not.

If you were closer, I'd give ya a ride... it's actually scary how fast the car is.

I have some videos somewhere...

Don't confuse lag with boost threshold, though they are related. Lag is the delay from depressing the throttle until the turbo spools/build boost. Boost threshold is where and how much boost a turbo makes at a given RPM.

Now that we're clear, the T04S and GT35R are VERY similar turbos with respect to boost threshold and power. Both will make 15 PSI at 3500 RPM (some say the 35R will make 15 PSI at 3400). The 35R has a slightly more efficient compressor wheel and I feel that the T04S has a better hot side for rotary power. There are probably more dyno plots out there showing an advantage toward the T04S, however, there are lot more T04S kits installed in FDs that have had years of tuning and development. We're finally starting to see some well tuned 35Rs making power that rivals the T04S.

If you are trying to choose between these two you should consider:

1. Costs (initial and replacement). The only T04S kit I'm aware of is the XS kit priced at about $3,500-$3,800. A-Spec makes a 35R kit for about $3500 which often goes on sale for $3K. If you build one yourself, it's easier to do with the T04S due to the T4 footprint and wide variety of manifolds available. The 35R will cost more to replace due to it's BB CHRA. At this point, you can't buy the CHRA and must purchase the whole turbo ($1395), but Garrett is supposedly going to make the centers available soon. T04S turbos are standard bearing and much cheaper. I've seen whole turbos for a little as $600-$800. CHRAs can be had for probably half of that.

2. Application. Again, both are similar. I picked the 35R due to the larger efficiency island where my turbo was going to operate (road racing). For me the slightly cooler intake charge was the primary advantage. For street use or drag racing, it's a wash. Ultimately, the T04S probably will make a bit more power due to better turbine effeciency.

3. Quality. Hands down, the A-Spec 35R kit offers much better quality than the XS T04S kit. Sean uses a TiAL WG with SS plumbing, HD flanges, flex and slip joint couplings, and nice welds. The XS kit that I saw utilized a mild steel DP, with poor welds and hardware. This might have changed since I saw the kit. Anyone have more info?

4. Maintenance. Ball bearing turbos may require more maintenance. In the past they have, but these new Garrett units are supposed to be superior in terms of longevity. Some have complained about cracks in exhaust manifolds on XS kits. I haven't heard of any failures among the A-Spec kits.

Good luck,

Gene

wargasm where do you live??

and thnx gfelber and wargasm for da info.

There's also the option of mating a 35R compressor to a T4 hotside. Personally, I'd like to see a 35R wheel mated to a GT4082 turbine. Most shops use a T04 turbine probably due to cost/availability. Precision Turbo makes a PT61 which NYT uses on his ride currently. That's a T04 turbine with the 35R wheel. He made well over 400rwhp using it.

I had an XS t04s kit. Had some issues with the kit but I do have a friend that has had no problems. I now run a turbo with a gt35r compressor - t4 turbine.

The turbos feel the same up to about 6.5k. The XS begins to slow down at this point. My new turbo with the gt35r compressor keeps pulling.

I rode in a friends car that has a A-spec 35r kit installed. From a visual inspection the kit is very nice. The seat of your pants feeling is awesome, gotta love BB.

XS T04S runs around $3200. Its a good deal considering you get a BOV and intercooler piping to the turbo.
I sell the GT35R for $2950 but you need a BOV ($180) and fab the intercooler pipe which is usually between $100-200 dollars. The kits end up being similar in price and also give very similar HP numbers.

Jason

manatecu & gfelber:

thanks guys for all the compliments on our GT35R turbo kit. We truely appreicate the positive feedback!

do you guys have any GT series setups for FC's?

According to the site, it's in development.

I just swapped my xs to4x for the gt35/40..I will let you know how it it feels soon.

neat. i will await it's completion with interest and then hopefully someone will guinea pig it :D

nyrx7,
thanks keep me posted

Yeah, i just purchased a GT35R kit from aspec, can't wait till I get it hooked up to the FD. Wasn't sure what kit I was going to go with but the fellow rx7club member that is helping me with my car had just visited A-spectunings HQ right before Christmas and said their build quality was excellent and so was the customer support. Plus he said that he has a freind with one on his FD that he uses on the track and said that his friend is really happy with it.

-Rob

then whats the difference at cheapturbos.com with the 35r wheel or something like that in the t04s cover to the to4s 60-1 wheel...etc....anyone know??

if you are referring to the turbos that i think you are, the gt35r they have at the bottom is listed as having a t3 hotside, where the t04s has a t04 hotside, while both using the t04s compressor side.