hmm, are you measuring spool up in seconds or psi at a certain rpm, even though lowering timing may get you full boost at an earlier rpm, it may be taking the same amount of time to get there, just that due to the lower timing rpm's are going up slower, allowing the turbo more time to spool up by a certain rpm. I mean boost may come on earlier but are you making more power? for instance 12psi with 15 degrees of timing may be better than 17psi with 4 degrees.

 

quicker spool=more torque

 

Only sure way to tell if it is faster is to datalog runs. the speed and time tells the real tale. run an average of 3 runs for each change to make sure. you can use 2nd gear to keep the speed lower.

 

EXACTLY ! !

That is my goal. I want to have more TQ than HP if it is possible with my setup.

Plus, High torque cars are a blast to drive. The power seems to come on instantly. For spirited twisty drives and AutoX, torque makes for a wonderful experience.

 

Well not necessarily. You have so many other physical properties playing in TQ.

Quicker spool = Torque Sooner, Torque = moving the mass faster.



As much as a tune can help HP TQ and Response, building the correct physical parts in a sequential order is just if not more important. 2.3L is in your future. I personally own a 2.3L Twin Scroll HTA3582 with a 1.00 hotside 550 TQ by 4,000 RPM.

Get the right physical properties then the tune...



Evan Smith

 

have you tried retarding the timing to -20/15 from 3500rpm to 6000rpm from 0-40 load? Does it help spool?

 

one thing about the IC and piping:

if you look at the way of the compressed air from the turbo on, you talk about, say, close to 2 meters of piping and IC up to the TB (in an evo ix, not sure abot the others and the x, but will ot be much less i guess).

now, every time the turbo starts to spool, it has to fill that whole intake system with air until you reach a certain pressure. so keeping the volume of the intake system from turbo to TB as low as possible will play a key role in how soon you can reach your desired boost pressure (short ways and/or small diameter).

that said, it is much more important for the IC to be very efficient (core design) rather than flowing so much (having a large cross-section area) and that the pipes also have a smaller rather than a large ID. therefore, the quality of an IC core for a torquey engine lies more in its flowing characteristcs than in its cooling capacity (which will be more important for top end).

also, any variations in airspeed should be avoided, especially any reduction in the width/area of whatever structure the air has to flow through (airspeed through the intercooler will most likely always be lower than through the pipes) because that will produce friction and heat, the bottleneck in most cases being the throttle body.

furthermore, you also want to keep all rubber couplers as short as possible - or the gap between the connected pipes, so to say.
i´ve once watched the silicon hoses on a BMW X3 with a retrofit supercharger expand when the engine was revved at a standstill, so a hard pipe will always be preferable to a hose.

exhaustwise, you want to keep your exhaust gasses hit that turbine wheel with as high speed as possible, so again, smaller diameter and smooth flow will be the key. which will of course not allow as much air to pass through the engine at WOT, but that will always be the tradeoff (and desired in this case).

and finally, to emphasize on the joy of having a torquey engine:
as you may know, in WRC, engine power is restricted to 300hp (with an intake restrictor).

so, citroen in their WRC C4 car is said to have extracted exactly that 300hp from their 2l engine - and 800Nm of torque...
now that should be a blast to drive

 

Please tell me that you are joking.

Anyway

I wish I knew the secrets the WRC guys know about making the torque they do.

What are every one's thoughts on header design for improving spool?

 

Just get a 2.4l, all the torque u need. Cant wait for my pistons to get here tuesday so i can build my 2.4l. That with a black or 6262 450-500ft/lbs. in a fwd eclipse haha.

 

Take a look at the 4B11 motor internally. The X's are readily making more torque than power. You could build the 4G63 with a similar profile.

 

That is like comparing apples to oranges.....not really feasible as they are completely different engines.

The purpose here is to discuss methods of TUNING that will make for faster spool. Not many are posting anything related to tuning.

 

With regards to WRC, realize they are using a system that doesn't really work for normal driving and really can't compare to what we are doing.

They use a diverter valve that directs air from the compressor outlet to the turbine inlet. The ECU then dumps in extra fuel and retards the ignition advance. Rich mixture + late flame front + extra air in the exhaust manifold = full blown combustion in the exhaust manifold.

You ever see those jet engines made from turbochargers... Same idea.

They don't really have instant spool because of "tuning," they just never let the turbocharger shaft speed drop. It's always high and it's just a mater of closing that diverter valve to have full boost.

 

I went the MAFT route, picked up spool a lot.

 

Nice... I never thought of that. Just like a gas turbine. I wonder what they make those turbine wheels out of to be able to handle that?

 

as much timing as possible before knock and 12.5-12.9 afr gave me a **** more torque, not sure on the spool