Turbo still not finalised ?

[prj]

David, even a 3076/0.82 is good in the city, because you can get full boost in 1st gear.
If you want torque from 1500 rpm buy a V8.

You either get full boost by about 3200 rpm MAX in 3rd and use 2nd in city (and that will be only stock turbo, maybe K24-7400).
Or you get full boost by upto about 4200 rpm max in 3rd and use 1st in city.

So basically 3400 to 4200 you will be always using 1st gear if you want to move the car fast.

And in that range you have from Garrett Range:
2871/0.82
3071/0.82
3076/0.82

KKK Range:
K24-7200
K26/K27 #6

Holset:
HX 35 Super

You have a fully built engine. Fitting a tiny turbo on that is a huge waste if you ask me.
You have all the supporting mods to go balls out and fit a HX35 Super or 3076R, or if you would want to re-use a maximum number of your current parts, a K26/K27.
Regardless of which you fit, you won't be able to use 2nd gear in town anyway if you want to go fast suddenly (and that's the ONLY place where lag matters).

The big advantage of Holset and KKK turbos is that they are rebuildable and their parts very cheap.

The whole question is about gearing. That's why I think the RS2 turbo and 2871 are pretty much useless, as the way you drive with them does not really change.
Due to all the mapping I've done, I've driven so many different combinations now...

[A80Avant]

even though people are getting some good results with comp, i would still be too scared to try one...

[Jamo]

Ct357 is silly money and K26 flange only a ct5658 from compturbo is better value

[A80Avant]

i think only DJones can say for that, but the car he is using it in is alaso very light, and setupwise very good, so it would bring the best out in any turbo

[macspring]

The casting configuration on a k26/3071 hybrid is a T31 housing or similar with a round cutout to match the k26 flange. A T3 flange has a much larger opening allowing for improved airflow resulting in better scavenging from the combustion chamber. This in turn means more fresh air to burn the fuel creating a more complete burn less prone to knock.

Thanks JP.

Never knew this.

So a T3 Wagner exhaust manifold with either a 2871 ( .63 or .82 ? ), or a 3071 ( .63 or .82 ? ) might suit best ?

No comments regarding the suitability of DJ Jones spec of a CT357 ?

Thanks.

[A80Avant]

and at the time there was no cyl.head porting. Only a service was done.

[Billman]

I am sold on the KKK hybrid solution. I think, conbined with head work and good mapping, you can have good round-town driveability and off boost performance. That said - if the car had been more of a project and I wasn't so keen to keep it close to stock I would have probably experimented with one of the new Borg Warner range.

Isn't off boost response better with a very big turbo helping the engine breathe? Plain thinking says that a small exhaust housing would restrict the airflow thus reducing the efficiency of the engine. (Not very relevant to the subject but i made me think about it).

When i drove A80Avant RS2 with the 3071/K26 hybrid it was when i had the RS2 turbo on my car and i have to say that i liked it a lot. It didn't felt laggier than the chipped RS2 I had a the time.

Of course i would also prefer the T3 version because of the flow, simplicity and many upgrade option.

Right now you want a good daily driver but you maybe see soon that a GT30 or 35 turbo drives very well also

[Ross]

I am sold on the KKK hybrid solution. I think, conbined with head work and good mapping, you can have good round-town driveability and off boost performance. That said - if the car had been more of a project and I wasn't so keen to keep it close to stock I would have probably experimented with one of the new Borg Warner range.

But it does sound like you're looking for a car with K24 like driveability - 2-5k torque range. I'd definitely take Diesel Des' offer up and see how you find that, because that is the only turbo i know of that (as far as I know) will give you the response you're looking for AND 400hp.

You'll find the K26/27 is laggier than you're used to low down, and even the RS2 hybrid (although not to the same extent but only good for 390-400hp) But the GT3071 needs to be driven above 3000rpm as well really - though with that BB centre it is quick to respond, and the headwork may improve it some.

What I'm saying is I do think you'd find that a nice, driveable car round town that isn't quite as fast as you're used to below 3,000rpm isn't such a bad thing. Especially with a nice smooth engine, you'll want the desire to rev it higher trust me

[prj]

Great info as always, thank you JP!

[A80Avant]

so really, when you ported the K26 housing on yours you made it slightly closer to the original T3 garrett one then ?

[JP]

The casting configuration on a k26/3071 hybrid is a T31 housing or similar with a round cutout to match the k26 flange. A T3 flange has a much larger opening allowing for improved airflow resulting in better scavenging from the combustion chamber. This in turn means more fresh air to burn the fuel creating a more complete burn less prone to knock.

[prj]

P.S.
What I meant to say before, is that 3071/K26 started knocking earlier than 3071/0.63 for me on very similar setups. Twice.
Why? I don't know... can only hazard a guess. Might be a coincidence as I said.

[prj]

I never mapped any K26/2871 hybrids or any 2871 for that matter at all.
Just hasn't happened.

And it might have been a coincidence, my guess is that the hotside of a 3071/K26 does not flow as well as 3071/0.63 with Garrett housing, that's all I can say.

[A80Avant]

Knock will be an issue for us when mapping as we cant get proper 98 fuel over here, we both use E5 as a substitute. As this will be Davids daily driver using any additives or octane booster isnt really an option. Weather this influences turbo choice i dont know?

Is say you will have a problem with any turbo I'm afraid. Consider water/meth injection as well to be safe.

sent using Android

[macspring]

Does the knocking happen with the K26 / 2871 also ?

What does a "if there is no fuel pressure taper" mean.

When you're were mapping a 26/27, what point does full boost occur ? And how much boost is there at say 2k rpm and 3K rpm ?

Low down the rev range will it drive as well as say a standard but chipped ABY Avant, or is there more lag and flatness with the 26/27, but much more poke when it does come on boost at x(?) rpm ?

Notwithstanding the above, my choice is either a 26/27 or a GT3071.

( The RS2 and 2871 should be left out of the turbos to choose from, because they don't suit what I want ? Is this right ? )

And so if I go for a 3071, I need to do the following;

I should swop my Wagner exhaust manifold for a T3 one and buy a 3071 .63, get the custom lines and the maf hose.

I know the K26 (#6)/27 will fit easier and be cheaper to buy and not necessate the purchase of custom lines, maf hose and manifold, but the 3071 should spool quicker and give as much bhp ?

You might confirm if I'm right or wrong ?

(I know you will anyway).

Thanks.