Can someone who has FULL knowledge and understanding of turbos explain what you are looking at on a compressor map and what you should look for when choosing turbos along with what an A/R is and trim. I've heard of choke areas on the map but what does that actually mean?

 

When turbos are referred to as being able to produce 'X' amount of BHP, would that be the same on 1.5litre of VG30DETT engine as it would on say an SR20DETT which is a bit bigger or is it application specific.

 

From what i've gathered, the smaller the turbine the quicker the you spool up to boost but less top end is achievable, and vice-versa on a larger turbine wheel. What differences does the size of the compressor wheel make? How do you get good spool up but still get high BHP figures?

 

Do turbos affect torque figures is that more internal engine component related?

 

The more info the better and anything else relevant you want to add would be great!

That's a big topic, have a look on the garret website, there's a few tutorials on how turbo's work and how to read the maps.

Nice one James, got my head around alot of it and some things were not as I previously thought. Still unsure if turbos have a large effect on torque output of an engine or not though, any info on that?

dunno if its along the same lines but iv always wonderd if on a twin..would a smaller turbo paird with a lager one work..like a small turbo to spool sooner then the larger one to produc the big boost n how the hell would u map that through one maf..or is ther a map that can do away with the maf ?

dunno if its along the same lines but iv always wonderd if on a twin..would a smaller turbo paird with a lager one work..like a small turbo to spool sooner then the larger one to produc the big boost n how the hell would u map that through one maf..or is ther a map that can do away with the maf ?

 

Sequential turbo set up, see the MKIV Supra (equal-sized turbos), FD3 RX7 (equal-sized turbos) & Legacy Twin Turbos (smaller + larger turbos) :)

That's called a sequential turbo setup, I think R33 and R34 Skylines use this but i'd imagine it's alot easier to plumb together on a straight 6 than a Zed. There's some good diagrams and descriptions of how it works in detail on the net if you're interested. Twin scroll turbos are interesting as well

Skyline GTRs (R32-R34) have parallel set-ups same as the Zed: 1 turbo per 3 cylinders.

ahh ok soo how would that be mapd to the zed if u were gona run that set up..i know u can get the selin two maf thingy ma gig but how would the remap go if you wanted to go mafless is that possible say you wanted a map going like small turbo boosting from say 2-4.5k then the bigger turbo kicking in from then till 8-9k..obvisly the engine would be biult to handle the stress but what would the mapping be involved as eggs has said how would the advance n trim n all other parimetrs go

At present, if you want to go for a MAP-based (speed-density) system on the Zed, you need to go for an aftermarket solution. I'm not sure it would be worth the large amount of plumbing involved to fit a sequential set-up on any V engine to be honest. You need exhaust gas from all 6 cylinders, plus various bypass valves to divert exhaust flow.

 

As for mapping, there's no difference in method between single, parallel or sequential set ups. Generally-speaking where timing is concerned, you would have the most advance in the low to mid-range areas on the big single, and the least amount of timing for the quick-spooling twin sequential. Very generally-speaking. Not 100% sure what you mean though mate.

so money no object how would one big say 1000bhp turbo plus plumbing compare to twin turbos or bi turbos compare how would the mps go?

what would be the better setup if chasing massive power

srry would u be ablle to run a twin through a mafless remap

so money no object how would one big say 1000bhp turbo plus plumbing compare to twin turbos or bi turbos compare how would the mps go?

what would be the better setup if chasing massive power

 

The big single would be laggy (high boost threshold), you'd be looking at a GT45 at the very least. The fueling map for a "laggy" large turbo set up is very different compared to the fueling requirements of your typical well-matched set up.

 

srry would u be ablle to run a twin through a mafless remap

 

Yeah, no problem with that at all. You would simply take the MAP reference pressure from the balance tube, if you were still running the stock plenum. You would also need an IAT (Intake Air Temp) sensor for the ECU to calculate the mass of the air entering the engine. With an aftermarket system, you need to map this variable (IAT compensation - typically a 2D table).

Examples

 

Normal set up

Fueling map from my forged & cammed 1998cc Pulsar running a standard T28H-sized turbo. Runs 12.08s@115mph 1/4 mile in the middle of summer:

 

 

 

Big turbo set up

Fueling map from my stock 1809cc 200SX S13 running a large "T70" turbocharger with 382bhp/326lb·ft @ hubs:

 

 

Both maps ran the respective cars at 11.5-12:1 AFR when on boost, despite looking completely different. Both on NIStune with Z32 MAFs. The S13 was running 510cc injectors, the Pulsar runs 560cc.

I think you're overcomplicating how the turbo changes the map.

 

the Map will be based on the amount of air the engine consumes and the effiency of that engine

 

The turbo helps drive the air, bigger the turbo, the more air, but usually accompanied by more lag. Though getting the right compressor/turbine ratios to suit the engine means that some work better than others

I think you're overcomplicating how the turbo changes the map.

 

the Map will be based on the amount of air the engine consumes and the effiency of that engine

 

The turbo helps drive the air, bigger the turbo, the more air, but usually accompanied by more lag. Though getting the right compressor/turbine ratios to suit the engine means that some work better than others

 

Is that meant for me?

 

If so, not in the slightest. Definitely not :)

 

Above are examples of actual fueling maps for the two different scenarios zhoodyx asked about. The specification of a turbo will have a massive influence over the shape of the fueling map, which is what was being asked unless I've read it wrongly. This is assuming the car is being mapped thoroughly & correctly, of course. Although they are for different engines, the overall shape show the difference between a typical twin-turbo and a big single fuel map :thumbup1:

No mate, not for you :)

No mate, not for you :)

 

Ah OK mate, now it makes sense. It was late and wondered if I was reading things correctly :laugh:

 

What you say is 100% true of course: The mapping methods involved are the same regardless of the turbo set up, be it big single, sequential or parallel.