Casting intake ports

[HenrikGM]

Hi.

Has anyone ever considered casting the floor in an intake port, instead of epoxying?

I have this huge V12 engine we are working on, with horrible bad ports inside. Short turn, is in fact not a turn, more a knife sharp 90degree.

The head is packing 2x 48mm intake valves, but flows horrible at anyhing over 5-.6mm lift.
Putty tests indicate that adding 15mm to the bottom, and just making a nicer short turn yields massive 40% increase in flow at higher lifts.

Now, If i were to buildt up the heads i would need several kgs of belzona or splashzone, giving some cost, plus potentially an issue with thermal loosening of the epoxy being a "chunk" of 15-20mm x 130mm wide and reaching some 70mm into the runners. I dont really like this thought.

So, i was thinking:

What if i made a steel insert in the valve pocket to protect the screw-in type valve seats.
Insert a hardened sand core to form the new runner, and simply poured the head full one port at a time, in turn creating the new runner when the sandcore is removed?

I would be conserned with the base material proprerties after the hot pour though....

on the other hand; if the epoxy was "castable" and methanol resistant, and cheap enough, we could cast the whole head, and roughmill out the runners for hand porting afterwards. I would need something in the range of 500cc pr port to do this though.

How would you attach this issue efficiently?

Feel free to answer in swedish, i read it well, just dont write it.

[David Herbertsson]

Jag har för mig att jag har sett "inserts" i portar som har varit skruvade? Kan det kanske va något? Det förutsätter ju att det finns material att gänga i och så. Är det en Rolls Royce Merlin V12? Isf. är jag avundsjuk, vill också ha en gigantmotor

/David

[Erland Cox]

Det går ju att gjuta i portarna men det man gjuter i krymper när det svalnar.

Erland

[inliner]

Tjena
Skulle det vara möjligt att blästra kanalen sen tennpasta följt av uppspackling med karosseritenn ?
Jag har gjort ett liknande jobb på ett par gjutjärnstoppar ,men då gjöt jag med zink ( smältpunkt ca 450 c?)
Som plugg använde jag mjukt isolertegel .
Mvh

[HenrikGM]

Yes, its a pair of meteor V12s (Almost merlins) for tractor pulling. Yes is its a big engine, and yes it will produce a massive explosion if run to the redline, and its just too fun fooling around with, but you need to think things ahead. Just a small backfire is an extreme event.

Last year we had it running like this on normal Vpower driven by a Megasquirt1 with good results after a steep learning curve on how much ignition advance this old rather hopeless design needs.
We ended up making ~4400Nm at 220kpa abs, max rpm 4000

http://www.youtube.com/watch?v=84vMl_kw ... ontext-cha" onclick="window.open(this.href);return false;

The team is now adding a second engine to the tractor, and the same time removing around 800kg from the tractor. Not much room for anything that wheighs when the tractor has a weight limit of 2500kg, including fuel and driver.

I can accept that it shrinks, as i will need to do something for the inlet flanges as well, so slight shrinkage is not too much is a problem. I would be concerned of the heat warping and/or softening the head though. Has anyone ever done the casting trick? After all the aluminium has to be around 740degrees when pouring.

Im not sure if the tin will work, but its also a very expencive material.

Ill see if i can figure a way to post a picture in here of what im trying to make.

[jonas landin]

We want pictures!
Upload on photobucket and copy/paste the img code!

[fredde_vit_pv]

Henrik,have you seen this? http://www.hundraknop.se/" onclick="window.open(this.href);return false;
some people from this forum is involved in updating on engine(s) setup!

/F

[Boxer Service]

Kommer ihåg en artikel i Power eller Wheels på tidlig 80 talet om en kille som gjöt upp en insats
til insugskanalen till Ford 351 Cleveland toppar. Han gjöt alu-insatsen i en form och insatsen limas
i kanalen.

Min tidligare granne har stor erfaring i alu gjultning och jag tror han kan och vil hjälpa till:)
Kom til Thisted (DK) och titta:o)

/Rolf

[HenrikGM]

Rolf:
Very interesting. Perhaps i should drop by Thisted in forseeable future!

Fredde;
I would like to get into contact with those guys. We likely have the same problems.

[mrjaybeeze]

en sådan ??



MvH
JB

[Tommy Luhr]

Ser ju ut som att det går att få lite flås i dom topparna. Dock inte med torra ögon.
Men prova att snygga till innerradien betydligt så skall du se att du inte behöver plasta flera kg

[HenrikGM]

Yes, it will make massive improvements with a better inner radius.
The problem is there are no material to make that radius in.

The port floor intersects the seat bore at a very sharp 90 degree.

If you go all in, it maybe possible to get a short turn with a radius of perhaps 2mm.

I will see if i can get a small video uploaded to youtube showing the port from different angles.

Another problem with the engine, is the room between the cylinder rows; to get a straight runner, it either has to be less than 80mm in lenght, or i need a quite abrubt bend right outside the port. Hence the wish for raising the entire port.
Im pretty sure a "bump" in the floor will yield good results, but then i still have the port entry problem.

[HenrikGM]

en sådan ??



MvH
JB

Yep, exactly. we are looking into the exhaust ports here. The intake is mostly a long "channel" and the floor is parralell to the head, and flat.

[HenrikGM]

have a look at what i have done so far.

No shiney work, no angle jobs, just doing a better short side radius.
basic port geometry made in the mill to have a baseline. The head was casted full of automotive putty, obviously only for the sake of testing it.
I have never had any luck with clay, as the flowbench usually rips if from the surface.
Port is minus 35% of the original area now.

http://youtu.be/65kVo2UF4Lc" onclick="window.open(this.href);return false;

Now to the big question; Does good flow apply to an engine with redline around 4000rpm, in a similar way as it does to one running 7000?
What port speeds to target?

[Jens Gustavsson]

Henrik,have you seen this? http://www.hundraknop.se/" onclick="window.open(this.href);return false;
some people from this forum is involved in updating on engine(s) setup!

/F

hej hendrik jag är inte direkt involverad i detta bygge men jag har varit och försökt hjälpa till med lite beräkningar av ett nytt insug och lite runt hur den andas. vi körde in så bra data som möjligt på mitt nyinköpta engine analyzer 3.9pro.
jag har sett insuget och håller med dig om att det är stort och med dålig effektivitet.

har du lite flödes data på insug och avgas? samt kamaxel tider?

jag skulle kunna simulera lite mer senare om jag har bättre data så kanske det både hjälper dig och båt grabbarna?

är det exakt samma grund motor ni har?

hur mycket för tändning bruka de behöva sugmotor? (då kan jag simulera förbrännings förloppen bättre)

mvh jens