Rb25 neo bottom end rebuild

[AngryRB]

47 minutes ago, WMDC35 said:

Ports are the same, seems strange they'd bother to make the head/ports different but then use the same gasket?

Yeah i think your right, just looking at the pics i have, must of been drinking some beer that day, neo is smaller but i dont think you need to bother port matching, the head ports are just a bit larger than the runners.

[AngryRB]

Top manifold is neo, bottom is R33

Neo runner, can see gasket doesn't fit perfectly, its slightly smaller than the gasket and around the injector is a lump.

Same gasket on R33 runner shows its a better match, bigger runners and no lump at the injector position which probably doesnt matter.

same gasket on the Neo head , so the neo head hasn't changed to be identical to the runners, seems to have continued same as R33 at that point.

[GTSBoy]

Higher runner velocity helps torque.  Small step into the port itself will cost some flow, but not much.  Not as bad as if it was the other way around!

[AngryRB]

you can see from the pics that the head has same size ports , the R33 manifold will be fine.. and save the stuffing around..

[dr phil]

Believe it is the N/A R34 head which has the smaller ports than R33, NOT the turbo head.

[vxsr33]

Ok, i comp tested my r33 today and here are the results.

I tested with all plugs out at once (not sure if this is right) and throttle body open. Keep in mind that i am using a cheap ebay comp tester so results may not be accurate. Car was warmed up idling for around 5 mins.

i know they are not the best results, but far better than no compression in cyl one that i was told.

[admS15]

Cyl 1 and 6 are a bit low but I wouldn't worry about it. Increase boost and keep running it until she won't run no more[emoji106]

If you had say 100 or under in a cylinder that would be something to worry about.

[Dose Pipe Sutututu]

those figures are fine, I wouldn't be too fussed... just ram loads of boost into the motor till it goes pop