GT500R-SP or GT3574R?
 

I was looking into the GT500R from A-Spec, and when I talked to Sean and told him what I wanted it for he suggested going with a GT3574R customized for my application.

I will mostly be using it for road course and possibly autocross (I know Rich, I know :lol: ), but I want to get decent top end from it too. This will most likely never see a drag strip, and only possibly see a few highway runs (I like going from a roll, that's why). I'm more into spirited backroad drives on curvy roads.

This is what the site says for the GT500R...
These setups are capable of 500whp@20psi with the right combination of build and a proper tune. We have seen 503whp@20psi on a large street ported motor. Most customers will see around 430-440whp in the 15-16psi range. With that 15psi being achieved around 3800rpm leaving you plenty of RPM to have a nice power band.

Sean said the GT3574R would be able to reach 14psi around 3400 and still be able to get up to around 450-500whp but it wouldn't be as efficient as the GT500R. He didn't say that verbatim, but that's what I gathered from information he gave me. Obviously this turbo would be ball bearing, and as I said, he said it would be customized for my application.

Being that the GT500R has great response for a good size turbo, it's really hard to turn your back on this one. However, the GT3574R has even better response and can still get pretty high into HP, just not as efficiently. I'm also getting the screamer pipe rerouted back into the DP, and getting everything ceramicoated. The GT500R kit costs a bit more. The customized GT3574R would be about $100 less.

FYI, I have an agressive streetport, RE monster VMIC, wide open exhaust with only a resonator to quiet it a bit (with GReddy Ti exhaust), 1000cc pri and 1600cc sec, HKS twin power, and more but I'm not sure what all matters for your advice.

So guys and gals, what do you think? Which one? Also, people that have either of these (although the customized one will be hard for someone to have haha), please chime in.

32 views and no one has an opinion? This is RX7club, I find that hard to believe haha.

You should listen to the advice given to you by your tuner/turbo builder. This is rx7 club, we're a bunch of carrot-timers in BAW. lol, all jokes aside, either option will make you happy.

Cant say i have any experience with the a spec kits. they look the goods i guess.

I like the gt3582. Brilliant powerband and not just a mountain horsepower figure.

well its really hard to give you advice because we don't know what exactly you will use this for. Are you trying to be competitive? you said road race and autocross but which level? For road racing are you in a class that uses a power / weight ratio ? If so then you should revert to the formula to see which turbo you need to accomplish your goal. If your autocrossing with a road racing setup you will not be competitive...

your also talking about a a custom turbo from a-spec. no one has had a chance to test it.

If you're referring to Sean when you say "tuner/turbo builder", then I tend to agree with you. I'm leaning more towards the smaller/faster spooling one. My actual tuner has only tuned an FB (carb'd) and my FD, which was his first and only FD so far. Several more of my buddies with FDs are getting tuned by him too. Don't get me wrong, he's a genius as a tuner, he tunes everything...sprint cars, rock crawlers, diesel trucks, motorcycles, you name it. He tunes MV Agusta's bike at Bonneville and he's going to their school in Italy, all expenses paid, to be the only tuner not working for the company to have their training. Something like that, haha. Edelbrock came into his shop and GAVE him $5000 worth of stuff and told him they wanted him to sell their parts. He is very careful with the car, WILL NOT tune it if he thinks something is mechanically wrong with it (until it gets fixed), has never lost an engine and gives it a very personal tune. And he only charged me $200, but that was mostly because I popped his FD cherry haha. With all that said though, he leaves it up to me to choose my turbo, so I assume you're speaking of Sean haha.

A-Spec has a great reputation from what I've seen, I haven't seen or heard anything bad about them yet, and Sean is a super nice guy and willing to help.

Are you talking about a GT3582 straight from Garrett? Where did you find this?

Yeah my bad, I wasn't real clear with all this. It's for an FD with the 13B-REW btw, I forgot I didn't post this in the 3rd Gen section. I haven't actually done any road course or autox yet. I have run my car on VIR but it was only parade laps, nothing competitive. As of yet I have no real knowledge of what classes allow this and what classes allow that, or anything like that. My main use for this will most likely be spirited drives on curvy roads to be quite honest, because I have a real problem getting motivated to get off my ass and go sign up and do what I have to do to actually get on the track or autox, haha. I'm more of an instant gratification kinda guy, which is what spirited drives gives me haha. But I do want to get into this stuff soon.

So it's kinda hard for me to say what class I want to be in and all that, I need to do more research for that. However, there doesn't seem to be much difference between these two turbos, the one spools a few hundred RPM faster and can still reach 500hp but not as efficiently...the other spools not as fast but still very good, and can reach 500hp with no problem.

My thinking is, there will always be someone out there who is faster, and I'm more into curvy roads, so there's not much need for the 500R for me. Although, there might be that new GT-R or a piece of domesticrap that I might need the extra top end for hahaha.

Yeah that's what I mean, it's hard for you to decide which would be better since there is no EXACT data on it. Although, there isn't really any exact data for the 500R either since every turbo will perform differently for different cars.

But I know what you're saying.

For autocross I would suggest the standard T3 version 35R. You'll be limited on top end power but you will want the quicker spool. Either way, any of Sean's kits are nice.

Not sure what you're saying, It's a 3574 BB unit, plenty have ran 3574's with good results his would only improve response.

As you can see Sean, I'm still on the fence haha, but I'm leaning towards the GT3574R.

what are the measurements on the 500R's compressor wheel? How does it compare to the GT40 or T04R class of turbos?

I my self have the gt3574. I did not know that a BB unit was even an option.

Eddie

It wasn't until recently ;)

Basically what Sean is saying is that the BB version will perform very similar, in terms of HP/TQ, to the non-BB unit but provide better overall response.

I've run his original GT35R kit for the last three years on a road race car. I've put in hour long sessions flogging my FC at 14 psi (about 400 rwhp I think (I only dyno'd at 8 lbs (340 rwhp) and 18 lbs (459 rwhp) so I'm assuming 14 psi is around 400.) Nothing but good things to say about his product. I'd ask him about the Tial hotside if I were you. I think that is going to be a killer combo for the roadcourse.

-Trent

What is different about the Tial hotside?

thewird

http://www.tialsport.com/prod_tc_tial_d.htm


How would the BB 3574 stack up against the 35RT4 with similar exhaust housings?

To the OP: I'd go with whatever your wallet & Sean recommend. :D

So the advantage is weight reduction on the hotside housing?

thewird

I would go for a bigger turbine housing becuse the only thing you get in higher rpm is back pressure and heat with a 82A/R housing. With a small turbin housing you get a good spool and great torque BUT the bad thing with a small turbine side is that you get to much power at once so the car is hard to drive.
I tried a GT500R but i switch to a T04Z and the car is mutch more easy to drive with good spool and enough power :)

There must be some mystique in naming turbos? Like this one, basically a plain old T04B "P-trim exhaust wheel" with an upgraded GT35R compressor wheel in a T04S cover. A slight twist to the original tried and true "meat and potatoes" 60-1 rotary turbo. :D

Sean, I had another concern. I heard somewhere that you guys will make sure the turbo and manifold seat together completely, that you machine both sides to make sure they sit flush, is that true? I had a problem with my current turbo and manifold and it kept blowing gaskets or it just wouldn't seal completely, so I got exhaust in the car when I turned the air on, not to mention the sound of an exhaust leak drove me up the wall eventually.

I hope you're asking someone at A-Spec, because I have no idea haha.

I know they make good products, that's why I'm going with them. It's good to hear praises from yet another person with their stuff, makes me feel like I'm pointed in the right direction haha. I also wonder about the Tial hotside, this is the first I've heard of it. Is that an option A-Spec offers?

Yeah that's what I'm thinking, he knows alot more about it than I do, and it helps that he has experience with not just turbos, but rotaries too.

That's the only thing I can see, but I'd like to know if there's more to it than weight difference. Depending on how much of a difference it would be, I might still be interested.

The turbo I've been using has a T67 wheel in a GT35R DBB housing, with a .68 hotside. It spools pretty damn fast and I have no complaints, other than I think I blew the oil seals while it was getting tuned haha. It wasn't hard to drive though. I'd much rather have the power real early than too late and have to wait for it to kick in. Thanks for your input!

Ive talked to the guys at A Spec about the 3574, and to me it doesnt sound like the right turbo. They use a bigger turbine side for more top end power, but also more lag. If you are on a road coarse our autocross you want better response.

I'd bet if you ran that turbo in the ball bearing version with a 0.84 divided tang. hotside with proper tubular manifold and downpipe, you'd change your mind.

.84 is a bit small for a divided housing, IMO. Sounds like a decent turbo, but there are others I would pick before it, like something in the GT series.

if your max power requirement is 500 then get the one that will spool there quicker...if you go with the GT3574R please post a dyno sheet with proper specs on your build so we can catalog it

You do realize this is the one Sean suggested I get over the GT500R, which spools pretty damn fast already, because this one spools even faster, right? LOL Are you talking about the GT3574 NON ball bearing?

This is a GT series...it's the GT3574R...GT series, ball bearing.

That's what I'm trying to find out, haha. More and more I'm leaning this way.

That's just it though, I'd LIKE to get 500whp, but it's not a requirement. I'm looking more for really fast spool, but these two are so similar already it's tough to pick. The GT500R already gets a good quick spool, but the GT3574R might give me that extra edge. Whatever I go with, I'll post up all the results.

Not sure what their GT500R is but I did see the 3573 is supposed to be a quicker spooler.

The 3574 has a P trim turbine wheel, not a GT wheel(GT wheels work better with twin scroll applications). The compressor is from a GT35. I would like to see how the 3574 compares with a 4088.

My suggestion, a GT35R with a 1.06 T4 twin scroll housing.

Just so you know, I haven't seen this exact turbo on their website yet, just the GT3574, not the R model that I'm looking at. Where did you get your information?

This is their 500R kit...

http://www.a-spectuning.com/html/products/gt500r.htm

They dont have any exact turbo info on the 500R, so its still a mystery to me what they use. As far as the 3574, I was pretty sure they used a P trim wheel. I decided to ask them, I was told they replace the hotside with a Garrett 74mm. They werent specific, but I knew they were talking about the old P trim wheel, its the only 74mm Garrett made. Something was mentioned earlier in the thread about a .82 divided housing, which just happens to be something used with a P trim wheel.

Eric, I really think a nice T4 35R will work perfectly for what you're looking to do.

Oh I see what you're saying now.

I thought the 3574R was better than the normal 35R though? I want something different too, know what I mean? I hear what you're saying though.

Oh wait, I see what it is...you just don't want me to end up with the 500R like you, hahaha.

If you want something different, I think I have just the thing for you. Ill shoot you a PM with some more info.

I appreciate all the extra input and ideas from everyone, but I'm choosing between the two I posted about. I trust Sean and his experience with turbos and rotaries, everyone has had good things to say about him and A-Spec, and these were the two we were talking about. Thanks.

With all this extra input it's just confusing me more, haha.

GT3582 directly off the shelf from garrett.

Dont waste money on anything fancy.
T04z is a gay turbo unless you can get your hands on the hks 1.00 housing.

They are now for 09. :)

Just so it's clear on this thread the 3574 non BB unit spools almost identical to a BB 35R T4 1.0 it's off a touch in transient response. But from a stand still you would think they were running the same turbo. The BB unit will outperform that unit. 3574's are not laggier due to a larger turbine. They actually respond better with the larger wheel having less compressor mass to rotate. A 35R T4 1.06 is nice but it will be less responsive on some cars between shifts. The 3574R is not a good comparison to the 4088R It will certainly respond better. It will definitely be a more fun responsive 450whp car. It will not put out the same power nor have the lag of the 4088.

You guys have any plans to do back to back dyno testing of these? Id certainly like to see it for curiousity sake.

Road course car
 

For a road race car my concern would be less on response and more on efficient power, as the car shouldn't fall below 4500 rpms. I've attached a graph with a 7800 rpm shift point, shifting our of first to second you fall to 4500 rpm, (which should never happen on a course, as first is way too low). All the other gears have you starting the new gear around 5500 rpm. With a well setup blow off valve and a good wastegate setup you shouldn't suffer too much boost lag in the shifts.
The killer on the roadcourse is heat. The turbo has to make great ariflow with minimal heat. The GT35R family seems right happy for the 13B in the 400-450 hp space.

cheers,
-Trent

After thinking about how everyone was offering different turbo setups and saying "don't spend so much money", etc., I feel I need to remind everyone that I'm paying extra for ceramicoating and rerouting the WG back into the DP. Not only that, these kits come with DP and manifold, both with a lifetime warranty, and a Tial 50mm WG as well. Considering all that, I think it's a pretty good deal.

And I've pretty much decided to go with the GT500R-SP.

Has anyone purchased the 500r hp, and do you have any dyno info??

anyone??

I bought the 500R-SP, but they're currently putting it together and I'm still deployed at the moment. I will be installing it mid May and hopefully get it on a dyno that first week I'm back before going home on leave. Although I won't have my water injection on yet. I will post up dyno info as soon as I have it.

I think I saw some somewhere on this forum already though.

This is my tune with a 3" full exhaust and Racing Beat dual-tip catback which I have reason to believe is hurting some power. Soon I'll try again with a 3.5" or 3.75" exhaust to see the difference. Wastgate is also plumbed into the exhaust. Also to note I get full boost at 4200-4300 even though the dyno suggests otherwise.

http://thewirdsdomain.com/rx7/dyno/dyno3.jpg

thewird

I am not sure if A-Spec supports these turbos but...

Evo guys have been having great success with Precision 6262s. They seem to spool faster than a 35r and have greater power potential. They also around the same price as the 35r. Unfortunately, the largest commercially available A/R for the turbo is .82. I am unaware of a rotary application that uses this turbo. I would give this turbo a look before purchasing as I believe that it fits your goals of quick spool and 500 whp capable. That said, again I do not know of an existing rotary 6262 car. The t3 flange combined with the .82 might be too restrictive on a hot rotary as well. Others are more qualified to comment on this than me.

Something to consider and good luck.

How much boost are you guys looking to run? If it's less than a frequent 20 psi, you're probably better off with a T4 35R in my opinion.

Well until I install the water injection (which will only be a few weeks at most) I'll be running no more than 15psi, but after that I was planning to run at least 20psi constantly, maybe up to 25psi or so, depending on whether I use just water or meth or some mix of both.

Yes we support them we carry precision and use precision as well as Garrett and BW.


There are ways around this. :)

A .82 T3 is a bit restrictive but a T4 depending on type and exducer diameter is fine for most. Our 3574's run a .84 T4 divided and have seen very nice power.

Hey Sean whats your take or do you have an real world experience on Precision's billet turbo's?

thewird

Hey Sean, how's my kit coming along? :) Did you guys get the EGT bungs?