Discussion and technical advice the SW20 MR2. 3S-GTE, 3S-GE, 3S-FE etc
Anything and everything to do with maintenance, modifications and electrical is in here for the Mk2.
Odin_S wrote:Not wanting to getting into the handbag fighting but i've noticed this alot on this forum. Why do you guys jump down bobhatton throat when he gives tuning advice? Maybe not a lot in this particular one but other i've seen.
I didn't jump down anyones throat, I just find it annoying when someone says "don't do this because this happens" without explaining why.
I understand that he obviously knows a hell of a lot, I just disagree with what he said and want to hear his reasoning behind it as the other have said
Mr.Two wrote:I understand that he obviously knows a hell of a lot, I just disagree with what he said and want to hear his reasoning behind it as the other have said
That's why I tried to explain for you...my guess is bob is talking about heat wrapping an exhaust in a turbo charged system:
ashley wrote:In theory wrapping the exhaust on an NA car will keep heat in the exhaust gas and increase the scavenging effects from the cylinders, and in effect increase power.
In theory in a turbo charged car, wrapping the exhaust after the turbo will keep heat in the exhaust gas, and as a result increase back pressure on the turbine. This reduces the pressure gradient across the turbine, and will reduce maximum power levels achieved.
In an MR2 however, will wrapping the exhaust of a turbo charged car reduce the temperatures in the engine bay, and so allow colder air to be ingested by the compressor and actually increase power?
Did I stress in theory enough?
Ren0W wrote:I used to pop (more BANG!) by flooring it to around 3-4000RPM, foot of pedal, let it drop to around 2-2500RPM and tap the pedal.
Every tap it was BANG BENG BENG BANG.
Could tap it around 5 times.
This was on my turbo tho, with a 3" NurSpecR, which made extremely loud bangs.
But yea, you could try it. (didn't need my engine/exhaust to be hot before doing this trick)
Done this myself, decat and SS system is what you want to do it. Im pretty sure it also happens when you run too lean not that its a good thing!
Also think (too) rich.
Had it mapped, so don't think he mapped it too lean.
He didn't went all the way and kept it pretty save. So guessing he kept it a bit rich.
Ashley so basically it's a compromise between cooler intake temps and exhaust pressure? Thanks for taking the time to explain that mate Just puzzles me a bit that WRC and competitive race series etc. usually use cerami-coated or heat wrapped exhaust components - even turbo blankets which surely have the same effect?
In all honesty I think any change in performance would be negligible anyway, especially in a relatively stock car Similar effect to fitting a cone filter..
Turbo blankets are good- they keep the heat in the turbo. Heat after the turbo is bad.
You are really aiming for as large a pressure difference across the turbine wheel as possible...so think heat into turbo = good, heat after turbo = bad.
I think WRC cars do heatwrap their downpipes (I think), but remember those cars are aiming for max midrange grunt, not necessarily top end max power. That and the fact they are already restricted anyway, so I guess the benefits of heat management outweigh the losses through turbine effeciency
My car pops and bangs all the time,a little tap of the pedal on overrun and it will bang once the car is warmed up, even more so with the new turbo kit
It took a lot of patience to get it neat. Well worth it in my eyes though.
My car is always popping and banging, probably due to the decat and over fuelling but setting off car alarms never gets old
Mr.Two wrote:Can't really see how increasing exhaust velocity would decrease power output.. But I'm interested to hear your opinion Bob?
The velocity is increased because the hot gas is expanded more than it would have been if it had been cooled down as much as possible.
The expanded gas has a greater volume so there will be a higher back pressure in the exhaust that the engine has to overcome, it has to push harder to get the gas out, or more of it will be left in the chambers.
Rally cars may well use it but they all have an inlet restrictor so have a limited power output.
Designer for turbo set ups on F1 cars, and Nitrous Oxide Systems of the USA in the 80s
Your boost pressure went up because the waste gate was unable to control the boost as the outlet pressure was much higher because of the increased back pressure after the turbo.
You can do a much better job by fitting a heat shield around the pipe, just not wrapping it.
Designer for turbo set ups on F1 cars, and Nitrous Oxide Systems of the USA in the 80s
Just puzzles me a bit that WRC and competitive race series etc.
Similar effect to fitting a cone filter.
