Jump to content
SAU Community

RB25DET Head porting info

mambastu

By mambastu,
in Engines & Forced Induction

 Share

Recommended Posts

Bl4cK32 Grand Master

Bl4cK32

Posted
Posted

yeah steve. I told u b4 its Chris Miltons. You got a qoute from them by memory, but it was too much? Interesting though - I have heard (on good authority) that the same work I'm getting done would've costed anywhere up to $1100 from another engine developers. Chris is pretty cheap - but it does save u to take the head off yourself :D

  • Replies 49
  • Created
  • Last Reply

Top Posters In This Topic

Popular Days

Top Posters In This Topic

Popular Days

  • 2 weeks later...
mambastu Collaborator

mambastu

Posted
  • Author
Posted

Hi All,

Head portings going well if slowly :)

I've been told that you should use an 80 grit sander for the final finish on the inlet port to promote fuel/air mixing but it looks a bit rough to me. Does anyone know if thats the correct finish for aluminium ? ;)

EnricoPalazzo Grand Master

EnricoPalazzo

Posted
Posted

I remember a while back i wanted to do this to my car. Basically i found out alot of good info on techniques and such. What i would personally do is go to some place which has old engine heads for scrap, and use it to practice the correct techniques. That way when it come to ur real head, u shouldnt have too much trouble.

Also A dremel i find is the perfect tool for this.

gtrhybrid Contributor

gtrhybrid

Posted
Posted

Funny you guys are on the subject cuz Im in the process of redoing my rb26 head. Im going through the head and porting and cleaning up the combustion chamber for better burn. Now, for the humps on the exhaust side, my theory on those is smooth them out as much as you can. If you were to run into a stud the worst that could happen is that you would have a very small exhaust leak through the stud itself (very unlikely). But it will pay nicely with power increased and better spool up too.

Cubes Grand Master

Cubes

Posted
Posted

Chris milton ported and polished up both the inlet and exhaust ports. He said some thing about concentrating on the bowl area.

He also cleaned up the combustion chamber so that the air was able to flow in to the cyclinder a little easier hence removed material and then polished that up also. On the Inlet valves he did a 3 angle valve job I think it was and on the exhaust he did a different valve job which made everything really round. I'll find out the exact terminology.

It ended up costing a little more than anticipated as he forgot to mention that its extra to shim the valves when setting up the hydraulics, not sure exactly but u get the idea.

  • 2 weeks later...
mambastu Collaborator

mambastu

Posted
  • Author
Posted

Finished the head now and pictures will follow shortly.

The porting was all done using a cheap air powered die grinder and a Standard Abrasives porting kit. Took me 3 days to do it but I reckon I could do one in 1.5 days now I know the areas to concentrate on. Hope this information is useful to everybody :)

mambastu Collaborator

mambastu

Posted
  • Author
Posted
Originally posted by -Joel-

damn.. My camera won't take pics that clear..

What camera are u using?

Its a Fuji S602 camera I think, its not mine its a mates.

I just edited the thread with a load of pictures and a description of what I did but its been rejected :) .......I'll do them as seperate posts.

mambastu Collaborator

mambastu

Posted
  • Author
Posted

The original exhaust port showing the intrusive port bumps

Exhaust%20Port%20standard.jpg

The finished exhaust ports....

All%20Exhaust%20Ports%20Finished.jpg

Exhaust%20Port%20Finished.jpg

Exhaust%20Port%20Finished%202.jpg

From the combustion chamber side....

Exhaust%20Port%20Finished%203.jpg

All of the intrusive exhaust port bumps were removed the ports were enlarged to the exhaust manifold gasket.

All casting marks were removed.

The divider was knife edged and the valve seat area was blended into the bowl.

The 'short' side of the port was radiused as there is a fairly sharp edge where the port turns into the bowl area.

The exhaust ports were finished with a finely polished shiney surface to slow carbon build up.

mambastu Collaborator

mambastu

Posted
  • Author
Posted

Standard inlet port....

Inlet%20Port%20standard.jpg

Finished inlet ports....

All%20Inlet%20Ports%20Finished.jpg

Inlet%20Port%20Finished%201.jpg

From the combustion chamber side....

Inlet%20Port%20Finished%202.jpg

The inlet ports are very well shaped in standard form and have 3 angle seats as standard.

Inlet ports were all enlarged to the inlet gasket.

The area where the valve seat meets the bowl was blended smoothly and all port casting marks were removed.

The divider was knife edged and the ports were finished using an 80 grit sanding roll to promote good fuel/air mixing.

mambastu Collaborator

mambastu

Posted
  • Author
Posted

Combustion chambers......

Combustion%20chambers.jpg

Combustion%20chamber.jpg

All combustion chambers were smoothed and polished thoroughly to reduce the likelihood of detonation and also to slow carbon buildup.

The combustion chamber shape has not been changed at all so compression ratio should be unnaffected.

  • 1 month later...
Mick Mentor

Mick

Posted
Posted

If you didnt have to buy a new head gasket when you remove the head i would grind and polish it all up myself... bit of a pain .. maybe one day when i need to rip the head ill do it ...

I got a question, ive got my exhaust manifold off at the moment and i was wondering if its a good idea to grind and smooth the inside of the manifold since its off anyways?

Another question i got is on the manifolds turbo outlet there is a divider in the middle that seperates the pipes - OOO|OOO -

anyone know if i can play around with that ? eg. like make it a knife edge or totaly remove it ... It has a slot in the middle of the divider as well ...

BOOSTD Mentor

BOOSTD

Posted
Posted

oh and make sure you don't go to thin as it will crack. Get a pinch measuring tool to check wall thickness. don't go under 2.5mm.

Also some of the bumps near the outlet are purposeful to direct the airflow around a the bend, these need to be smoothed rather than removed.

Be carefull knife-edging the outlet as a heat fatigued piece of broken metal will kill your turbo in a second.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • MBS206
      Duncan's V37.......race car?

      By MBS206 · Posted

      Even more fun, leave all the ADAS stuff plugged in, but in different locations, hopefully avoid any codes!   And honestly, all these new cars with their weird electronics. Pull all the electronics out Duncan, and just shove an aftermarket ECU and if needed a trans controller in, along with a PDM. Make it run basic but race car styled!
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      To follow up a question from earlier too since I had the front bar off again (fking!) This is what is between the bumper and the drivers side wheel And this is the navigator side, only one thing but its a biggy! So basically....no putting coolers in the wheel arches without a lot of moving other stuff. Assuming I move to properly race prepping this car I'll take that job on and see how the computers respond to removing a whole bunch of ADAS modules
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      So I prepped the car for another track day on Wednesday (will be interesting to see coolant temps post flushing out and the larger reservoir, with a forecast of 3-14 being 20o cooler than last time I took it out). Couple of things to mention; since I am just driving the car and not taking a support vehicle, I took the rear seats out and just loaded the back up Team Trackday style. Look at all that space! To cover off removing the rear seat....it is weird (note the hybrid is probably different because it wouldn't have folding rear seats) Basically, you remove the lower seat base, very similar to a r series but it is a clip that pulls forward to release the base rather than it being bolted down. Easy Then, you need to remove the side section of the rear seat on each side. There is a 14mm head nut at the bottom of the side piece, the it slides upwards off a hook at the top to release; you also need to unhook the seatbelt from the loop at the top. Then the centre piece is weird. You need to release/fold the seats forward with the tab in the boot on each side From there, there are 2,x12mm headed bolts holding the rear of each seat to the folding bracket, under the trim between the rear seat and the boot (4x christmas tree clips there, they suck). The seat is out but you can see where the bolts attach to the bracket
    • RP1421
      S15 Spec R

      By RP1421 · Posted

      As discussed in the previous post, the bushes in the 110 needed replacing. I took this opportunity to replace the castor bushes, the front lower control arm, lower the car and get the alignment dialled in with new tyres. I took it down to Alignment Motorsports on the GC to get this work done and also get more out of the Shockworks as I felt like I wasn't getting the full use out of them.  To cut a very long story short, it ended up being the case the passenger side castor arm wouldn't accept the brand new bush as the sleeve had worn badly enough to the point you could push the new bush in by hand and completely through. Trying a pair of TRD bushes didn't fix the issue either (I had originally gone with Hardrace bushes). We needed to urgently source another castor arm, and thankfully this was sourced and the guys at the shop worked on my car until 7pm on a Saturday to get everything done. The car rides a lot nicer now with the suspension dialled in properly. Lowered the car a little as well to suit the lower profile front tyres, and just bring the car down generally. Eternally thankful for the guys down at the shop to get the car sorted, we both pulled big favours from our contacts to get it done on the Saturday.  Also plugged in the new Stedi foglights into the S15, and even from a quick test in the garage I'm keen to see how they look out on the road. I had some concerns about the length of the LED body and whether it'd fit in the foglight housing but it's fine.  I've got a small window coming up next month where I'll likely get a little paint work done on the 110 to remove the rear wing, add a boot wing and roof wing, get the side skirt fixed up and colour match the little panel on the tail lights so that I can install some badges that I've kept in storage. I'm also tempted to put in a new pair of headlights on the 110.  Until then, here's some more pictures from Easter this year. 
    • joshuaho96
      R32 GTS (RB20DE) Injectors Replacement

      By joshuaho96 · Posted

      I would put a fuel pressure gauge between the filter and the fuel rail, see if it's maintaining good fuel pressure at idle going up to the point when it stalls. Do you see any strange behavior in commanded fuel leading up to the point when it stalls? You might have to start going through the service manual and doing a long list of sensor tests if it's not the fuel system for whatever reason.
×
×
  • Create New...