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Hi all,

I know there is plenty of info on the outputs of specific turbos and combos of all sorts on here, and about every upgrade imaginable, but I have a slightly different question, I have a garrett t04z on my 25 thats been going well for many years, im making 360rwkw on 98 vortex with about 450cc/min of water meth, all this on stock cams too.

I know the t04z is a very old designed and somewhat laggy turbo, and on my setup its making 22psi at 5000 revs, with a 1.05 exhaust housing.

My questions are, should I look at a new turbo? Something like a gtx3076r for my power levels?

Im quite happy with 360kw and not very interested in much more. I can still almost double the meth im running for more power, plus cams would get more again, I see the 3076 making mid 300's easily but I want the room for 400kw, mainly for if I ever go e85.

Or is my most economical option putting a .83 rear on and keeping my current turbo?

Is it going to make it come on at 4k?

Is there an option that will make 400kw and come on by under 4?

I really dont mind the lag that much, but feel I could be doing better easier.

And finally fitment, will any of my options fit straight on where the t04z sits, in regards to the manifold, v-band 3 inch dump, and 4 inch inlet? I realise things will need modifying, just need to know what im in for.

Just looking for options, as I may do something in the near future if I see it being worth it, and what others recommend.

Hoping iv given all the info required. Thanks

Better can definitely be had for your particular setup.

A Precision 6262 CEA should be available in a housing config similar to your T04Z which will improve spool and add power. That is a first suggestion without major outlay which will improve power and spool.

If you want to stay sub 400kw but want the best of the best for a reasonable 'swap over' an FP 3582 HTA will probably be for you. A 3586 HTA is likely to be an awesome compromise if you want way more power, it will probably stretch out to mid 400s rather than the mid 3s mentioned though lol as will a 6262 CEA.

That should tell you what you want to know.

Thanks for the input, how are the hta for reliability? Im not going to head for mid 400's, maybe 400 absolute tops. Im pretty sure its just a t4 discopotato03

And whats more preferable in regards to HTA and precision?

And is the difference going to be where I notice a huge difference?

The HTA is just a modified Garrett so reliability is on your side... The only downside to these turbos is the cost, other than that they are a damn good choice for RBs

Precision are cheaper and will also get the job done well, have read a couple of reliability things BUT never seen any first hand so it could just be haters online :P

On E85 there is usually a 40kws of gain, if the tuner knows what he's doing.

On E85. Unless you put some cams in it. Or using factory cams:

A GT30 based turbocharger can not make over 400rwkws

A GT35 based turbocharger make get over 400rwkws, but can not make 24psi (minimum requirement to reach 400rwkws) any where near 4000rpms.

You will need our Alpha turbo systems to do this. And trailing result of 407rwkws with 24psi by 3700rpms using factory cams and E85.

On E85 there is usually a 40kws of gain, if the tuner knows what he's doing.

On E85. Unless you put some cams in it. Or using factory cams:

A GT30 based turbocharger can not make over 400rwkws

A GT35 based turbocharger make get over 400rwkws, but can not make 24psi (minimum requirement to reach 400rwkws) any where near 4000rpms.

You will need our Alpha turbo systems to do this. And trailing result of 407rwkws with 24psi by 3700rpms using factory cams and E85.

You could go close enough!

I found Pump 98 is tinny bit more responsive, probably due to the extra heat:

Boost response. 98 (Purple) V E85

http://www.hypergearturbos.com/images/dynosheets/atr43/atr43ss2/290612/e85boost.jpg

I found the same thing Stao, perhaps the extra carbon content in the exhaust stream?

A GTX3076 would almost get you 400kw, (with a large AR rear) but not with the response of the Hypergear, or the HTA from the few results I have seen. e85 would be a must at that boost though.

I found the same thing Stao, perhaps the extra carbon content in the exhaust stream?

A GTX3076 would almost get you 400kw, (with a large AR rear) but not with the response of the Hypergear, or the HTA from the few results I have seen. e85 would be a must at that boost though.

The 2 HTA3076 results are 391kw with restrictive exhaust and 396kw with small inadequate intercooler! Still both were pushed and both seemed to make similar power! Mine was done on E70 pump fuel and stock motor + Headgasket, the other with proper E85 and built engine i believe. 20psi @ 3700rpm.... Still i reckon you would need to push pretty hard to make the magic 400kw mark but tbh in the 34 it just wouldnt matter, it bursts into wheelspin if you mash the throttle and down low it feels SO good....

I STILL dont have my flex fuel dyno sheets :dry: but i believe pump 98 was in the 330kw region as it wasnt pushed to higher boost levels.

I found the same thing Stao, perhaps the extra carbon content in the exhaust stream?

It would have to be because of temperature. Extra "carbon" in the exhaust is not a useful factor. Simplistically, E85 exhaust would have the larger volume. There are more molecules of exhaust gas per unit of power made (or per unit of air consumed) because there are two O atoms in each CO2 and only one O atom in each H2O. So fuels that produce more water produce more volume. But that's the volume when expressed simply in terms of number of molecules. If you jam another 100°C exhaust temperature then that would add up to a larger change in actual volume in the exhaust. Once you've done all the maths and worked out that with basically the same mass rate of exhaust flow (there would actually be slightly more mass rate with E85, but ignore that for the moment) travelling at a higher velocity (simply because it is hotter and takes up more room) the 98 exhaust has more momentum. And that's just looking at it simplistically. If you go fully thermodynamic in your consideration, then now you're looking at the ex manifold pressure as well, and so looking at the total energy available in the exhaust (and what fraction of it is available to extract across the turbine). The simplistic view is sufficient to explain what we see here though.

Edited by GTSBoy

The 2 HTA3076 results are 391kw with restrictive exhaust and 396kw with small inadequate intercooler! Still both were pushed and both seemed to make similar power! Mine was done on E70 pump fuel and stock motor + Headgasket, the other with proper E85 and built engine i believe. 20psi @ 3700rpm.... Still i reckon you would need to push pretty hard to make the magic 400kw mark but tbh in the 34 it just wouldnt matter, it bursts into wheelspin if you mash the throttle and down low it feels SO good....

I STILL dont have my flex fuel dyno sheets :dry: but i believe pump 98 was in the 330kw region as it wasnt pushed to higher boost levels.

True, he will need cams to get this sort of result. The 407rwkws that I've archived is on stock cams with lesser boost.

I don't know the exact wheel profile of the HTA item, how ever SS3's turbine wheel is larger then whats in the GT30s. It should pump more power on your setup.

On E85 there is usually a 40kws of gain, if the tuner knows what he's doing.

On E85. Unless you put some cams in it. Or using factory cams:

A GT30 based turbocharger can not make over 400rwkws

A GT35 based turbocharger make get over 400rwkws, but can not make 24psi (minimum requirement to reach 400rwkws) any where near 4000rpms.

You will need our Alpha turbo systems to do this. And trailing result of 407rwkws with 24psi by 3700rpms using factory cams and E85.

A GT3582R HTA will get 24psi near 4000rpm - as with a Borg Warner EFR8374, and they have proven reliability.

True, he will need cams to get this sort of result. The 407rwkws that I've archived is on stock cams with lesser boost.

I don't know the exact wheel profile of the HTA item, how ever SS3's turbine wheel is larger then whats in the GT30s. It should pump more power on your setup.

You didn't make 407rwkw, you made 407kw @ hubs - it'd be interesting to see it if would crack 400kw on that boost with stock cams, as I don't think I have seen anyone else do that with an RB25 despite some using similar or larger turbos. Unless proven otherwise I am far from convinced that the reason you have make that extra power versus cars run on other dynos on that boost on stock cams should be attributed to the turbo itself.

Comparing turbine wheel sizes between different turbine designs to determine flow is folly as well - a Borg Warner 8375 has a ~75mm turbine wheel compared to a 68mm Garrett one yet they are very comparable in terms of flow. Doesn't mean it won't, but certainly doesn't guarantee it will.

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