Guys, i am in the process of playing with the new toy, a BBR turbo converted MX5.
Over on the mx5 forum it seems the general consensus is 12 psi is about the limited.
My question is this, in a very naive way. What factors limit boost? If the general opinion is a mx5 can handle 220 ish hp, what factor does the boost have on this, could i not for example run "x" brand of turbo at say 10 psi to achieve this or "y" brand at 14 psi.
I guess my question in basic terms is, cant i run whatever boost to achieve "x" horsepower so long as supporting mods, fuelling, wastegate etc can deliver?
Can depend on a lot of things.
Boost makes more power (sorry if sounding patronising!!) by forcing a bigger mass of air (by volume) into the engine. The air flow sensor reads this bigger flow and puts in more fuel accordingly. More fuel = more power.
Now, above a certain point increased fuelling requires a few things. Chiefly bigger capacity injectors, bigger fuel rail, more powerful fuel pump. Without these things, you will run lean, engine temperatures will rocket, detonation will occur and something will break.
At the other end of the equation, the drivetrain on all cars is designed to a certain value of power that it can handle, usually with a 30-50% margin on top of the highest factory output of the engine. Go above this and you will risk lunching clutches, gearboxes, diffs, etc. So big power mods tend to get these bits replaced as well.
No doubt others will have opinions, but thats my starter for ten to begin with!!
graeme
Understood buddy and no it wasnt patronising! I get all that, but why on forced induction does it make a difference what boost levels you run if
a) you have the necessary fuelling mods
b) your not exceeding the drive line capabilities
c) your not exceeding the "bhp" that the internals are also capable of
d) intake temps are good
e) water temps are good
f) the turbo is within its boundaries
Compression Ratio is to high on a N/A engine which will cause detonation at a certain boost, in your case 12psi.
Low compression pistons or larger combustion chambers in head depending on engine design would enable higher boost before detonation.
Or could do it the cheap way and fit 2 head gaskets with a 1mm steel template of a gasket in between but that would Knock your valve timing out so you would need vernier pulleys.
Phil
you could hook up WI to run more boost? get it mapped with the water and you will avoid det.
the limiting factor is really the point at which you get compressor surge, as long as you can manage any problems with detonation.
sorry to hijack but is this possible on a standerd ecu? in my case a 94 13b import? an i take it FPR would be needed to?
Quote from: trotter;697276Chiefly bigger capacity injectors, bigger fuel rail, more powerful fuel pump