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Can you get a biggler AR turbine housing to slightly reduce boost from 2.9K to 3.8K and so stop surge? I am sure that the map could be modified at these rpm to reduce the boost slightly in that range also. What boost is it running through surge point? What boost are you running at high rpm? Approx BHP/torque? How "laggy" is it compared to k24?
- It was with .86 ar turbine housing (did not feel laggy )
- ex manifold is tubular welded rs2 equivalent
- boost SW is modified to get rid of surge and reduces hp/NM
- not laggy compared to S2 stock kkk24
- BHP torque not measured, but seat feling ~320-330hp (friends estimate), but considerably stronger than the S2 kkk24. S4 Avant is a heavy car.
With the software modified how does the car drive? Does it feel much faster than stock turbo? Compared to RS2 setup? What exhaust manifold are you running?
With the software modified how does the car drive? Does it feel much faster than stock turbo? Compared to RS2 setup? What exhaust manifold are you running?
It is much faster allready due to more power level of about 50 to 60 hp.
Car is very convenient to drive. It is not with agressive boost kick.
Difficult to compare to C4 S4 with rs2 setup because no experience of that.
EX manifold is tubular rs2 equivalent with no wg. Connecting rods are from eagle. WG is integrated to turbo.
Boost after 6000 is not at the level you expect. Such small turbo can not be driven with high boost level of 1,5bar at 7000 (with small stock IC). The owner wanted to have durability to his daily driver and therefore moderate boost levels.
One of my friends installed a GT2871RS to his S6, stock engine except RS2 manifold, injectors, fuelpump, BN pipes exhaust (no cat, but original downpipe) and 3 bar map. I gtech'ed him to approx 270 hk at the wheels, 400 NM. He will do additional mapping when he has changed the downpipe.
The interresting thing though, was that when we tested side by side (ur-S4, approx same weight, chipped with no other engine mods), he would pull away from me in andy rpm range! So he has a bunch of extra horses, and still it spools better than my k24. That is a good deal. He did not have any surge problems though.
One of my friends installed a GT2871RS to his S6, stock engine except RS2 manifold, injectors, fuelpump, BN pipes exhaust (no cat, but original downpipe) and 3 bar map. I gtech'ed him to approx 270 hk at the wheels, 400 NM. He will do additional mapping when he has changed the downpipe.
The interresting thing though, was that when we tested side by side (ur-S4, approx same weight, chipped with no other engine mods), he would pull away from me in andy rpm range! So he has a bunch of extra horses, and still it spools better than my k24. That is a good deal. He did not have any surge problems though.
J
Heh like i said earlier in the thread 2871R is better suited to the I5 engine, the 3071R would be the best for drive and bhp gains and then the 3076R for all out balls HP but spooling around that of a RS2 turbo.
Is the surge problem now cured? And can turbo surge easily be cured by reducing boost (via WG spring or mapping) at the given rpm range?
I am probably going for a GT28RS (or similair) myself too. As I am desperate to find the "smallest" ballbearing turbo available to reach 350 bhp and 500 Nm (which seems to be on the "very" safe side of the stock bottom end and cams...).
I have read on the 034 site that the GT2871 can be tuned up to 400 bhp which makes it a bit of a doubt for the stock bottom end and cams...
Only too bad the GT28RS is with an internal wastegate...
That internal wastegate severely puts me off the 'disco potato' as well - external WG is the way to go... but you are right not to discount the GT28RS as the dimensions could be in the right ball park for that spec... Sure its easy to hit those figures with a GT3071R (or bigger) but you get less tractability & lightly slower spoolup at the lowend and more lag - nature of the beast.
I'm trying to achieve a similar aim with my Frankenstein K24/RS2 hybrid turbo - its still on the bench... I need to get the slightly smaller hotside housing of K24 machined to fit otherwise standard RS2 turbo. This should give slight benefit in spool time and lag, but it won't be as good as one of these sexy Garret roller bearing turbos.
Trouble is if you have a turbo capable of 400 or 450 bhp you do want to get it to that level...
It is a bit like with the first Escort RS Cosworth, it has a large T35 and 8.0:1 CR, but still Ford only mapped it to 227 bhp... Makes no sense to me... Although they did correct that (only half, only the turbo, not the CR) with the latest T25 much more drivable engine...
But still nowadays they would do that with a much smaller ballbearing turbo with "very" high CR. Like the 225 bhp Megane RS is doing. If you would compare torque and power curves from both engines the Megane must be the better...
I can see the point why all those first Escort drivers will bring it up to at least 330 bhp the specs are there for it and so it is bang easy to do! And now the downsides of the CR and more laggy turbo will be compensated for massively! Try that in your Megane!
About the internal wastegate... You would think that Garrett is not stupid and maybe the internal wastegate of the GT28RS is of a very good design? I am not sure, maybe we are thinking to much oldschool... I wonder how 034 deal with the downpipe and exhaust manifold for this one?
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