This is in my 182 track car.
While the engine was out I polished the manifold tracts and did my best to match the ports on the 2 intake sections and head. I also cleaned up the exhaust ports and internal welds on the exhaust manifold.
I then fitted a 62mm throttle body, calculating that it gives about 14% increase in TB intake area.
I honestly did not expect this to have any effect on the car at all, just something to do over the winter.
Pretty much all the knowledge on here says larger TB has no effect, as the manifold tracts are the limiting factor, and polishing/porting really doesn't do much.
I have since done 3 swaps from 62mm TB, back to 60mm and back again etc. And I am pretty sure there is a small performance gain in the 62mm TB. Better response at low rpm, which is giving a better corner exit and a couple of mph top speed gain down the tiny straights at Lydden Hill. The result being around 4 tenths quicker laps, very worthwhile. I'm afraid I only have lap times and data logging as evidence, no dyno readings.
Anyway it has a bit of a downside in that when the 62mm TB is fitted the breather pressure or volume seems much higher.
This first showed itself by blowing the dipstick out and covering the front of the engine with oil! It then blew the crankcase breather pipe off the connection at the rear of the engine and giving that a good coating.!
Running the crankcase breather to atmosphere via a catch tank has cured this.
The rocker cover breather now seems to be a problem.
The tiny hole that blows into the intake manifold is difficult to seal with the weird gasket. It relies on the manifold having no deformation or slight warping, otherwise when you tighten the bolts on the front of the intake you are lifting the breather seal at the rear.
So this has manifested itself by venting oil onto the rocker cover, filling the first spark plug well and causing a misfire!
Put the bloody 60mm TB back on and have done with it I hear you say!
But having convinced myself the 62mm TB offers a few tenths that would be defeatist.
So how do I vent the rocker cover to the catch tank, while keeping the OEM intake manifold.
Thinking of doing something with the oil filler cap, like making one with a hose connection.
Any thoughts welcome
While the engine was out I polished the manifold tracts and did my best to match the ports on the 2 intake sections and head. I also cleaned up the exhaust ports and internal welds on the exhaust manifold.
I then fitted a 62mm throttle body, calculating that it gives about 14% increase in TB intake area.
I honestly did not expect this to have any effect on the car at all, just something to do over the winter.
Pretty much all the knowledge on here says larger TB has no effect, as the manifold tracts are the limiting factor, and polishing/porting really doesn't do much.
I have since done 3 swaps from 62mm TB, back to 60mm and back again etc. And I am pretty sure there is a small performance gain in the 62mm TB. Better response at low rpm, which is giving a better corner exit and a couple of mph top speed gain down the tiny straights at Lydden Hill. The result being around 4 tenths quicker laps, very worthwhile. I'm afraid I only have lap times and data logging as evidence, no dyno readings.
Anyway it has a bit of a downside in that when the 62mm TB is fitted the breather pressure or volume seems much higher.
This first showed itself by blowing the dipstick out and covering the front of the engine with oil! It then blew the crankcase breather pipe off the connection at the rear of the engine and giving that a good coating.!
Running the crankcase breather to atmosphere via a catch tank has cured this.
The rocker cover breather now seems to be a problem.
The tiny hole that blows into the intake manifold is difficult to seal with the weird gasket. It relies on the manifold having no deformation or slight warping, otherwise when you tighten the bolts on the front of the intake you are lifting the breather seal at the rear.
So this has manifested itself by venting oil onto the rocker cover, filling the first spark plug well and causing a misfire!
Put the bloody 60mm TB back on and have done with it I hear you say!
But having convinced myself the 62mm TB offers a few tenths that would be defeatist.
So how do I vent the rocker cover to the catch tank, while keeping the OEM intake manifold.
Thinking of doing something with the oil filler cap, like making one with a hose connection.
Any thoughts welcome
