[Mk2] [Turbo] A/Rs and HP

[Martin F]

I managed to squeeze 389 rwhp from a GT3076 with a 0.63 A/R however it only goes to a certain power output then drops rather than rising. I put this down to the 0.63 A/R .

Because of this I am running slightly lower boost for my high boost setting, 1.88 bar maybe which is seeing 378 whp, graph is pretty similar to the higher figure (which I don't have a printout off).




Car runs lovely on the road with barely noticeable lag however I have ran out of things to modify so would like opinions on where to go next.
What would the effects be if I changed the housing to a 0.84 or even a 1.04 ?? A/R ?

I am definitely interested in getting more top end bhp but don't want to end up with lag.

Should I maybe be looking at a totally different turbo kit ? Ashleys recent dyno run is destroying every level of my Garrett at similar boost. Not sure if I want all that out and out rawness he is dealing with now but maybe an in between would satisfy my needs

Thoughts on this from the people in the know ?

P.S. Here is a printout from wastegate pressure with no start duty, a bit more lag but feels nice on the road, dyno plot says what I am trying to achieve with my higher boost setting...

[androo007]

Best bet is sell me the turbo kit and get a bigger one for sure.....

[Martin F]

Best bet is sell me the turbo kit and get a bigger one for sure.....

HaHa, How's your motor coming along ? Must be pretty close to dyno time

[pbmr2]

Not on a 3sgte but on other 2.0 engines I've had .86A/R and this was a nice move. Was good for well over 400hp. (8.2k rpm limit)

There isn't really loads of lag but the strong push builds 5-800rpm later but doesn't relent.

On a much larger 3.0L had a 1.06A/R and this did lag a fair bit. managed to tune out a lot and changed boost controller and waste gate but it still needed many revs to get all the power.

For around 4-450ish hp on a 2.0, felt the .86A/R was about right.

Without more displacement, above about 450 lag is inevitable. Keep it in the rev range and it's madness

[Martin F]

Not on a 3sgte but on other 2.0 engines I've had .86A/R and this was a nice move. Was good for well over 400hp. (8.2k rpm limit)

There isn't really loads of lag but the strong push builds 5-800rpm later but doesn't relent.

On a much larger 3.0L had a 1.06A/R and this did lag a fair bit. managed to tune out a lot and changed boost controller and waste gate but it still needed many revs to get all the power.

For around 4-450ish hp on a 2.0, felt the .86A/R was about right.

Without more displacement, above about 450 lag is inevitable. Keep it in the rev range and it's madness

I am seeing over 450 bhp on the 0.63 from 5500-6500 but then it drops bhp from there to the rev limit (not much but I would rather it went up than down), do you think the 0.86 A/R would help me achieve this and by how much ?

[ashley]

It depends what you mean by lag, if you mean boost threshold- then you are already struggling- you don't make any real power until you are passed 4.5k rpm...increasing the size of your turbine housing will make this worse, but it will release more top end power...0.82 would work well. 1.06 will potentially let you make a load of power, but it'll be a pain to drive unless you don't mind staying above 5k rpm the whole time!

If you want better response and more power then you need a new turbo....sorry!

[Martin F]

If you want better response and more power then you need a new turbo....sorry!

What would you suggest ? would have to be a kit as I don't have the means to buy a turbo and build the downpipe etc. myself.....

[ashley]

Depends- how much hp do you want?

[Martin F]

Depends- how much hp do you want?

500-550 ish, depends on what my current fueling set up could handle I suppose as I only have 800cc injectors and they are all ready running out of steam 86% duty at high rpm

Think it may be best just to change to a 0.84 or whatever size it is On my current set up and see how I feel, if that could break into the 500+ bhp range I guess for now I would probably be quite content

For talking sake what turbo would suit me for 550-600 bhp at higher boost but I could use at lower boost until I upgraded the fuel system ?
No harm in pricing things up and doing the appropriate research, just don't know where to start ,

[androo007]

Best bet is sell me the turbo kit and get a bigger one for sure.....

HaHa, How's your motor coming along ? Must be pretty close to dyno time

No comment...had to cancel dyno time twice already

But seriously from my (limited) knowledge looking into the td06 upgrades if applied in general it does seem unless you want more puff up top to chase numbers the best thing is to get a new turbo to suit your power goal rather than force an outsized turbo to work.

[Martin F]

Best bet is sell me the turbo kit and get a bigger one for sure.....

HaHa, How's your motor coming along ? Must be pretty close to dyno time

No comment...had to cancel dyno time twice already

But seriously from my (limited) knowledge looking into the td06 upgrades if applied in general it does seem unless you want more puff up top to chase numbers the best thing is to get a new turbo to suit your power goal rather than force an outsized turbo to work.

hopefully I will get some suitable advice on this thread, i'm pretty sure I can offset much of the cost by selling my current turbo as well

Are you still having oil pressure issues ? any other problems ? you'll get there

[ashley]

Well a GTX3071 / GT3071HTA should do 500hp on the right engine, Paul nearly cracked it with his:

Thanks to Ash for the guidance with the turbo choice. I know you put a lot of research into it in the past, and don't worry, I have no issue with the GTX3071, except that it is insanely difficulties drive in the damp on r888's....


Before diving into the graphs, I have to point out that my objectives for this session were not based on peak power figures. I had no expectations that the 3071 would compete with the 35r. The main objective was to spool quicker and to raise the Rev limit, with the peat power being incidental. Having said that, I was always hoping for 450hp.

As is well publicised, the car made 550hp and 530lb at 2 bar on the GT35.

So, after a few runs, this was the peak power run with the car running at 1.7 bar:


So a nice peak of nearly 500Hp with spool between 4000 and 4800 rpm, and power maintained to 7200 rpm. All looking good.

I was hoping to run the boost at 2 bar as everything I've read says the gtx turbos really need to be boosted to realise their potential. Ryan said that it probably wouldn't make much more than 500 though without risking reliability. He detected some knock on the run above, so wound it back a little. I was happy with that as I wasn't chasing figures and would rather the car survived a season of racing rather than having bragging rights

So this the final run and the high power map as it stands :



[email protected] 430lb torque.

So I lost 60hp and about 100torques, but gained about 2000rpm on the power band.

The,drive back from Surrey, on the 1 bar map felt insane. The way the power comes on is exactly what I was looking for, though I think I need to learn to drive a bit better now as it is not forgiving when accelerating around bends!

Personally I think the HTA wheel has more top end flow capabilities- with the GT3071HTA I think Paul would have seen over 500hp...but he has cams and a 2.2l bottom end.

The next step up would be the 76mm compressor wheel, which can flow >600hp but the GT30 Turbine housing will prevent you making that much...I've not seen an GT3076HTA on a 3SGTE, so I really don't know where the limit would be...the main thing with the design of the heads on our cars seems to be getting the exhaust gases out, they really don't like back pressure.

So the next obvious step would be the GTX35/ GT35 HTA...but then you are going to raise you boost threshold, but potentially unlock all the top end flow.

That is the route I went down, and I have to say where you do increase boost threshold, the HTA wheel seems to make up for it....basically giving you early spool and top end flow...


But there are also other options- the BW are supposed to be good (although I've "heard" that they don't seem to have the top end flow capabilities of other brands), then there is Precision- these units seem to be making the best numbers at the moment, with good spool...the only doubt in my mind is the build quality and how long they do/ don't last.


Personally I would sacrifice top end flow for early spool and lots of mid range torque on a road car...I've driven with high power, slightly later spool and with less power, but insanely early spool...and the latter makes for a much more enjoyable, driveable road warrior! Big power is extremely exciting to drive, but you don't have as many opportunities on the road to use it...

[C35Rob]

Martin,

If your current injector duty cycle is peaking @ 86% then you're already out of injector going by the 'safe' rule of thumb of not pushing injectors past 85%DC , so really, you'll need to go bigger, either drop in 850's or a top feed set up with something else (plenty to chose from, another topic entirely)

As for the turbo, sound advice from Ashley there re peak power vs drivability, I'm sure a car with a wider, flatter power band would feel a lot faster and be better suited to what you want from it

There are options other than a whole new 'kit' for you though. Many turbos will use, the same footprint as your current one so would be able to be a direct swap.

As Ashley said, a smaller gtx3071 wheel will flow a little more air than your current 76 and spin up faster, maybe more what you're looking for.

A BWs252sx-e has a smaller wheel still (but a larger turbine wheel, more evenly matched than the Garrett..) but still flows more air than the 3076 - this is the turbo that Sheppy has, and TBH the one I wish I'd bought.

The next step up would be a S257SX-e, similarly sized to the 3076 but flows much more air, and every B2B dyno chart I've seen shows them spooling faster than the equivalent Garrett, despite not being ball bearing, and making a fair bit more power pretty much everywhere.

There's lots to think about.. Sheppy got his BW from AGP turbo in the states, they offer a garret Footprint housing with their turbos, so you'd literally be able to remove your 3076 and bolt up a new one to your manifold adapter/downpipe.

[Martin F]

Well a GTX3071 / GT3071HTA should do 500hp on the right engine, Paul nearly cracked it with




Personally I think the HTA wheel has more top end flow capabilities- with the GT3071HTA I think Paul would have seen over 500hp...but he has cams and a 2.2l bottom end.

The next step up would be the 76mm compressor wheel, which can flow >600hp but the GT30 Turbine housing will prevent you making that much...I've not seen an GT3076HTA on a 3SGTE, so I really don't know where the limit would be...the main thing with the design of the heads on our cars seems to be getting the exhaust gases out, they really don't like back pressure.

So the next obvious step would be the GTX35/ GT35 HTA...but then you are going to raise you boost threshold, but potentially unlock all the top end flow.

That is the route I went down, and I have to say where you do increase boost threshold, the HTA wheel seems to make up for it....basically giving you early spool and top end flow...


But there are also other options- the BW are supposed to be good (although I've "heard" that they don't seem to have the top end flow capabilities of other brands), then there is Precision- these units seem to be making the best numbers at the moment, with good spool...the only doubt in my mind is the build quality and how long they do/ don't last.


Personally I would sacrifice top end flow for early spool and lots of mid range torque on a road car...I've driven with high power, slightly later spool and with less power, but insanely early spool...and the latter makes for a much more enjoyable, driveable road warrior! Big power is extremely exciting to drive, but you don't have as many opportunities on the road to use it...

This is the kind of graph I would like to have on the car, if i'm doing this however I would like it to be future proof so would like a turbo that could get me into the 550+ area if required. Is there a turbo out there that would suit me ? Gould the GTX3071 get me there with higher boost ?
It all goes over my head due to so many makes and choices.
Obviously either a full kit or one that had the same footprint as the garrett.

Thanks for your opinion on this one ash, you have done a lot of research and I am counting on your knowledge... ,

[Martin F]

Martin,

If your current injector duty cycle is peaking @ 86% then you're already out of injector going by the 'safe' rule of thumb of not pushing injectors past 85%DC , so really, you'll need to go bigger, either drop in 850's or a top feed set up with something else (plenty to chose from, another topic entirely)

As for the turbo, sound advice from Ashley there re peak power vs drivability, I'm sure a car with a wider, flatter power band would feel a lot faster and be better suited to what you want from it

There are options other than a whole new 'kit' for you though. Many turbos will use, the same footprint as your current one so would be able to be a direct swap.

As Ashley said, a smaller gtx3071 wheel will flow a little more air than your current 76 and spin up faster, maybe more what you're looking for.

A BWs252sx-e has a smaller wheel still (but a larger turbine wheel, more evenly matched than the Garrett..) but still flows more air than the 3076 - this is the turbo that Sheppy has, and TBH the one I wish I'd bought.

The next step up would be a S257SX-e, similarly sized to the 3076 but flows much more air, and every B2B dyno chart I've seen shows them spooling faster than the equivalent Garrett, despite not being ball bearing, and making a fair bit more power pretty much everywhere.

There's lots to think about.. Sheppy got his BW from AGP turbo in the states, they offer a garret Footprint housing with their turbos, so you'd literally be able to remove your 3076 and bolt up a new one to your manifold adapter/downpipe.

Thanks for your Input Rob, Would 850cc injectors be a straight swap and handle the possibilities of 550 bhp ?

Does it get much more complicated if I need 1000cc injectors ? ie. are they plug and play or would I need new wiring, fuel lines, fuel rail etc. ?

It's such a shame sheppy has put his build on hold, his first hand experience would have been great, could have even maybe got a run in his car to get a better idea....

[C35Rob]

Thanks for your Input Rob, Would 850cc injectors be a straight swap and handle the possibilities of 550 bhp ?

Denso/Sard 850's drop in to the stock rail with the addition of adapter collars (they're a different shape at the bottom) if your current 800's are high imp (brown colour) then your resistor pack will already be bypassed, if they are the rarer low impedance blues then you'll need to bypass the resistor, however it's a 10 min job.

people have made 500bhp on 850's, I don't know what sort of duty cycle they were running though, I expect it's more than ideal.

Does it get much more complicated if I need 1000cc injectors ? ie. are they plug and play or would I need new wiring, fuel lines, fuel rail etc. ?

not complicated no, you can buy a kit if you wish, or you can buy a rail and injectors separately, you are looking at around £1000 by the time you've bought injectors, a rail, a new FPR and some hoses and ends though.

It's worth pointing out that modern disc type injectors atomise fuel much better than old pintle injectors, and the spray pattern is often better, so you can end up with a lower BSFC than a comparably sized side feed

[Martin F]

Thanks for your Input Rob, Would 850cc injectors be a straight swap and handle the possibilities of 550 bhp ?

Denso/Sard 850's drop in to the stock rail with the addition of adapter collars (they're a different shape at the bottom) if your current 800's are high imp (brown colour) then your resistor pack will already be bypassed, if they are the rarer low impedance blues then you'll need to bypass the resistor, however it's a 10 min job.

people have made 500bhp on 850's, I don't know what sort of duty cycle they were running though, I expect it's more than ideal.

Not sure about my injector colour but going to high a bhp is going to take away road driving enjoyment. I will try and source a set of 850cc sard injectors. if you can advise me on the collars I need that would be great.

The bogwarner turbo that sheppy bought looks great, cheaper than a garrett but can be bought with the same footprint so would be pretty much a direct swap.
Can you recommend what one I would need, be nice if it was capable of around 550 bhp give or take however I may not have the need for that, (just prefer to have extra bhp available for future requirements if chosen).

You know what else I am looking for, your thoughts ?

Thanks Rob

[C35Rob]

S252SX-E flows 55lb/min so good for 525ish bhp, will be an awesome all rounder, I severely regret not buying one myself.

S257SX-E flows 65lb/min so good for 625ish with the correct supporting mods, but will spool a little slower (although still faster than what you've got right now)

collars - ask sheppy where he got his from, they're pricy from japan but I think he sourced them quite cheaply from the states

My thoughts? response and low down power will be more enjoyable to drive on the road than something that makes pub numbers for a nanosecond right at the top of the rev range.

[Martin F]

S252SX-E flows 55lb/min so good for 525ish bhp, will be an awesome all rounder, I severely regret not buying one myself.

S257SX-E flows 65lb/min so good for 625ish with the correct supporting mods, but will spool a little slower (although still faster than what you've got right now)

collars - ask sheppy where he got his from, they're pricy from japan but I think he sourced them quite cheaply from the states

My thoughts? response and low down power will be more enjoyable to drive on the road than something that makes pub numbers for a nanosecond right at the top of the rev range.

So you thinking 850cc injectors and the S252sx-e will meet my needs ? Will certainly be the cheaper option (which suits me) and by the sounds of things be better right through the rev range.
I won't be fitting this until next spring so have plenty time to research but it sounds exactly what i'm wanting.
when on the website I get lots of options in a drop down menu, what should I be looking at choosing from them ?
Sorry to be taxing your time, not clued up on all the choices

[sky-net]

But there are also other options- the BW are supposed to be good (although I've "heard" that they don't seem to have the top end flow capabilities of other brands), then there is Precision- these units seem to be making the best numbers at the moment, with good spool...the only doubt in my mind is the build quality and how long they do/ don't last.

I'm wondering exactly the same about Precision ones. I'd like to pick one brand new if everything goes fine. (pte5130)

I never have find a BW turbo kit for mr2. Does anyone sells them?

Regards