Rebuilding My 930

[Blanco]

Excellent thread...

[beepbeep]

Great pics.

Now that you have everything in piceces and heads in the machine shop, why not go whole nine yards (right expression? :-) and machine dual-plug holes?

If you are going to run MS & Spark, it won't cost you anything more...just extra set of plugs, cables and wastefire coils. you could even drill those holes and plug them with spark-plags, to be used later when ignition is ironed out.

good luck!

[350HP930]

Originally posted by snowman
Good info. Are you going to flow the heads? If so please post data. Tnx.

Yes, the heads will be flowed when I am done with the initial porting work and that will be well documented and posted in its own thread like my balancing work.

Originally posted by 125shifter
I bored mine to 40mm, not realizing the Carrera intake is really 41mm. I had to go back and do some hand work to match them.

My manifold only measures 40.5 mm but those damn plastic spacers are 41.5 mm. That kind of pisses me off but I will do my best to line up and match everything.

I have thought about twin plugging but with flat top pistons I think its overkill. I would much rather put that money towards the flame rings I am contemplating.

I had a chance to bore another head and do a little rough clean up on the intake ports today.

[Saintly]

Originally posted by 350HP930
Yes, the heads will be flowed when I am done with the initial porting work and that will be well documented and posted in its own thread like my balancing work.

Don't forget to post a link to that new thread in here for the people following your work.

[snowman]

Mad scientist, thank you for your substancial contributions to this forum. Real hard data and pictures are worth their weight in gold.

[350HP930]

Well, since everyone loves pics I took a few more today when I bored out the remaining heads. Enjoy . . .

[350HP930]

My Super Hi-Tech Alignment System.


Target Locked !


Let The Carnage Begin


I Could Never Imagine Removing All This Material With A Die Grinder


And a shot of all the bored out heads . . .

[DonE]

I Could Never Imagine Removing All This Material With A Die Grinder

Some of us did exactly that..

[turbo6bar]

How'd ya clamp the cylinder head down to the table, 350HP930?
Jurgen

[350HP930]

I made a jig that bolted to the head that held it at the proper angle.

After that it was just a matter of centering the boring tool and making a 1.55" deep hole.

As the pics show it worked out perfectly. I have finished most of the detailed porting work so its almost time for me to post some more pics and begin flow testing my heads.

[snowman]

Your head flows should be much more consistant than ones done with a die grinder, although the difference with a die grinder between cylinders may only ammount to something on the order of 0.5% or less in HP variation. Nice job.

[350HP930]

I too think that the consistancy of my intake bores and valve chamber areas should make for some very even flows. Though my porting work is not done yet as the pics below show all I have really had to do is blend the transition areas and remove some casting roughness.

I imagine I will have a bit of clean up work to do to the carrera manifold to even up all the cylinder flows though.

[snowman]

Very nice.

Question- on the top of the top photo is the short side radius. Is this smoothed and round as well? The reason I am asking is this is the place where I find most of the improvement in head flow. Do you find the same thing?

To clarify, if the port size is not increased I have found something like 95% of the flow improvement is just from smoothing out the short side radius. This increase is usually almost 20% when the radius is sharp. I understand that making the port bigger will also increase the maximum port capabillity, the flow will be larger but if the short side radius is still sharp you will be about 20 % below achievable flow.

[350HP930]

Yes, smooth radiuses all the way around, especially on the short side.

My education in fluid dynamics has me paying a lot of attention to preventing 'detached flows'.

What I would give to have access to a decent digitiser and a good CFD program.

[snowman]

A good CFD program would be very nice, especially if it can be had for next to nothing. This should be possible. I was an independant consultant, purchased a top of the line Agelent tech. Microwave simulation program, now selling for about $110K plus. Once I retired I could not give it away. There must be the same sort of thing available on the CFD market.


I have to add this info somewhere so here it is. On the Caddy Northstar engine (1999) I am rebuilding. The piston rings are very very thin as they should be. The valves have half the sealing surface width the old engines had, eg about 0.025" on intakes and 0.030" on exhaust. The valve margins are next to nothing ie 1/10 what they were. The piston clearence is almost nothing at 0.001", the weight balance is all withing one gram. The head flows will support twice the advertized HP without any porting, ie just change out the cams. That means over 500HP with just a cam change. ( of course carbs or injectors must be compatible with the extra power). That folks is out of a 4.6L v8. The most amazing thing is that its all aluiminum, therefore very light. That means it can power A PORSCHE!!! I am opposed to 350 conversions to a Porsche, but this Caddy engine, being light enough and powerfull enough,is an other matter. I am seriously thinking about it.

[350HP930]

There are lots of good CFD products out there, but they are very pricey. I could write my own program for purely laminar flows but I am interested in what could be determined by a program that would model the non linear stuff that I no longer have the zen to tackle myself.

[ToyCollector]

Great thread. I just dropped the motor and tranny on my 930 to replace the clutch and will be ripping things apart for at least new gaskets, lines, possibly a turbo, etc. Thanks for such detail.



Edited to insert pic. I doubt mine will compare to this, so I promise to not post anymore here other than for questions.

[350HP930]

Ugh, this was certainly the weekend for some messy work.

Now that the engine is about ready to come together I decided it was finally time to start prepping the engine compartment.

It was a big reminder of what an oily and dirty mess everything was before this whole project got started.

I spent a good chuck of saturday removing all the stuff like the A/C compresor, condensor, lines, relay box, oil breather and some trim in the tail that blocked off the grill slats that were not directly above the old intercooler and condensor.

Oh yeah, there were also all the old dry rotted rubber engine tin gaskets and the foam that was still hanging around from the insulation pad and pass through area for the plumbing and electrical stuff that needed to be removed too.

I still have a lot of cleaning and painting work to do, but at least all the big chunks are gone.

As usual I have pics of the progress . . .

It didn't take long for debris to build up under my work area.


A better view of the carnage


A lot of oil grime to go around too.


And my pile of stuff I won't be using again.

[snowman]

Great pictures.

When youall get to the alignment. let us know the final numbers. I use -1.25 degrees camber in front, and -2.5 degrees in the rear of my race car. Toe equal to zero both front and back.

[logician]

When I pulled the engine in my 930, I got rid of that sound insulation above the engine. I like the way it sounds without it. And it gives better access inside the engine compartment.

-Juan