To port and Polish or not to; that IS the question

[dpuckett]

I have concluded I am going to have to do a head gasket this coming week. I plan on going with the updated gasket, and get the kit. I guess I should have asked this earlier- What are the advantages of the marine HG vs stock? ANd should I get a thicker one? Have no real EGT issues, but OTOH, since I have the head off, I may as well set myself up for the future. But money is tight, and I do have the 9mm injector holes. Might be better off getting a 7mm head if I am going to go all out.



Second- I stopped by a machine shop in town today to ask if he could check the head for craks and flatness. Said he could. ASked about porting, and he said the exhaust is the only part that can be ported. I thought both intake and exhaust could be. He also said that you want to leave the intake a little rought to swirl and tumble the air as it ocmes in. I thought when you ported, you did it to increase flow in AND out. Was I wrong? I am also a little leery about him porting because- 1] there arent many diesels around here anyway; no one does a lot in the line of performance mods beyond the occasional Banks kit. 2] He mentioned nothing of bench floeing the head like is mentioned on the PDR website; and I know you can mess things up if you dont get it all right the first time. 3] I was under the impression you COULD port both intake and exhaust. He quoted me $150 for the port and polish; $60 to mill (if needed);$105 for 3 angle grind, and install new valve seals. THis seemed a little low compared to what i had seen on here from guys who do it all the time. Kind of brings to mind that old saying "You get what you pay for. " But this is swampeast MO, and everything's cheaper here.

 

[keimmmo]

I have ported a lot of heads for both gasoline and diesel motors. I have never had the luxury of a flow bench... I just use proven methods of the pros and go for the big and easy gains and don't worry about spending hours trying to get the last cfm. I have always had favorable results.



With a gasoline motor on the street, fuel vaporization is an issue. For that reason, it is best not to go much bigger on the intake side and leave things a little rough. Polish to your heart's content on the exhaust side, but still don't go too big... too big on a gas motor will do more harm than good unless it is a high rpm race only motor.



A diesel is a different world! The more air you can move the better! Since the fuel is injected into the cylinder, there are no vaporization issues. I would port and polish BOTH sides on a diesel!!!



Unshrouding the valves on ANY motor helps the flow and performance. Seems to really help a diesel!



I question the knowledge of your friend regarding head porting. Don't have enough information to know how well he would do the rest of the work.



Steve

 

[Philip]

He also said that you want to leave the intake a little rought to swirl and tumble the air as it ocmes in.

If you were building a NA gas engine this is true. A high polish on a air fuel mixture can cause fuel puddling or seperation as it is called. BUT we use a forced induction system. So that statement does not apply. Plus our setup does not use wet air/fuel air charge. So seperation is not an issue at all.



Find someone that has the know how and the equipment to flow the head properly. If it is done wrong. It can cause less air to flow than you have now.



The last full port and polish I had done on a pair of heads cost $1,500. This was 20 years ago. They were done by C. J. Batten.



What is he planing on doing on the valve guides? I see no mention of that work in your price list.

 

[dpuckett]

My gut kind of had the same feeling as you guys

So I probably wont have him do anything more than check for cracks and flatness. My novice eyes could miss something, and I dont have a KNOWN true straight edge. Do you guys know of anyone in the Denver/ Colo Spgs area to get things like that done? If I go stock for now, I'll probably run it that way for a while, and be back in CO by the time I have the money to get it done up good. With my original injectors, turned up pump PDR HX35, and the bad gasket, I'm still over 19 mpg city (light foot aff the line). Since I dont PLAN to do any heavy towing, I'll most likely stay where I'm at; though it is nice to dream and mull over porting, polishing, cams, injectors, intercooler, etc, etc.



THanks, guys.



Daniel

 

[BushWakr - RIP]

Hey Dan,





What I'll pass on to you is "as best I can recall"... .

The heads on our trucks have a slightly lower flow rate than any other head on these trucks. It's not overly huge in it's deficiencies but it is there.

At PDR a stage 1 porting is somewhere about $1200 ( I stand to be smacked and corrected if this is not right) but the point is there are alot of hours to do it right and match the flow in and out of each cylinder. Keep in mind this is done using a flow bench to confirm each step.



(The heads that used the 9mm are more prone to cracking without removal of head material. They usually crack between the intake/exhaust seats, but can also crack around the valve seat itself. )



Both intake and exhaust are done when porting, you are quite right there...

It would be the best move to use a newer head if you can come up with the $$.

There is a couple places on the head that should NOT be touched as they can actually hinder flow rather than help. I recall Piers saying that to me clearly.

3 angle grind is done on the higher HP trucks but if it's cheap to get done, and you trust them to do it right, go for it.



Can I suggest you contact PDR, speak with Piers and explain your situation. He will likely tell you if it's worth your trouble or not.

Last, he may even be able to help you with a pre-done head... . I don't know if he has one with the smaller injector holes or not, but it's a cheap phone call.

Describe your situation as you posted it here, and go from there.

You won't find they are looking to stroke and gouge you there, I can assure you of that.



As for the head gasket, it will depend on how much if any comes off the head (assuming you use your original) as to whether you need a thicker head gasket.

You should be able to use the "updated" gasket for the 12 valve head and expect good service from it... . unless you're going for a new 1st Gen HP record. . then... hang on...



I hope that helps some, and my apologies if I've made any errors or spoken out of turn.



Regards, Bob.

 

[dpuckett]

Thanks

BushWakr-

I have just about decided to go with stock specs for now. I thought about it last night, and I just cant afford to go the other route now (especially if some redneck gasser guy messes it up). I had my suspicions about the guy when I was talking to him, and I may find a different shop to even check for flatness/ cracking. Or is that a fairly easy thing to do? There should be an obvious place where the gasket blew, shouldnt there? Or will it not be so obvious? WHat are the specs for fatness, warping, etc? I know it is only a few thousandths of an inch. Later in the week, I may give Piers a call- you're right, he's one of the few shops I've dealt with who wont gouge you just to make a quick buck; he seems genuinely interested in doing right by the customer.



Daniel

 

[Steve Graham]

What about "Extrude-hone" where they force a abrasive-mud mix through the ports for porting? Sounds like it would be a cost effective solution?

Steve

 

[hdm48]

Dp, I would reconcider having this guy do any port work if he does not understand VE. And I'm not talking about pumps here. I'm talking about the engines ability to breath.

Both intake and exhaust need to be done. Don't worry too much about the swirl. It will still happen. And polish as much as you can. Remember, we are not moving fuel with the intake charge so puddling is not an issue, max flow is. Just because some guy has a flow bench doesn't make him an expert. I build champion motors and I do not use a flow bench.

If you want it ported, got to a race engine builder or PDR or Dynomite Diesel. Just make sure you deal with some one that knows what their doing or you will be buying a new head or worse. And don't forget the externals. Porting the head only will help but doing the intake system and exhaust system will make it complete. Just go and look at a real race motor and you will see what I mean.

Porting is very expensive for a reason. It's a lot of work. And it takes a lot of knowledge.





Dave

 

["Mad Max"]

I iknow a 'guy'

DP, for the head work contact Cotty Hayes at Cylinder Heads Plus in COS, (719) 638-6556. Tell him I sent you- He'll laugh a lot and call me a bunch of colorful words and then he'll ask you if my Demon is still running - tell him it's still scary fast and he can drive it next time I'm stationed there. He speaks 'porting and polishing' like a big dog and he'll give you an estimate even if you tell him you probably will wait. He's a good dude and knows his stuff.

- Sam