Porting and polishing queries.

[Slam]

Salutations, all,

Good to find this board - I've been reading and learning for a week or two and have a couple of questions.

I've got an '83 944 that I've had an interesting love/hate relationship with for about ten years now. I know the car very well as a result - plus, I'm a much better mechanic than I was way back then. Grins...

The engine is up for a rebuild this winter (I'm a Canuck - we get two seasons here: Drive and Repair) and was wondering about porting and polishing the head. I've got rid of the cat, having replaced it with a straight pipe to the stock muffler. Got some joy there. I'm planning to get the Wilks chip as part of the winter's program. That's about it. It seems the dollars-to-power ratio is undesirable when it comes to extreme modifications.

Given the chip and the free-flow exhaust, would a port and polish job make much difference to performance?

Cheers,

Slam
83 944 - mine
82 931 - her project

[adrian jaye]

usually I'd say yes,

but I'm sure that some here say it can cause more problems than is worth.

usually a de-coke does the trick

HTH

Ade

[nynor]

i have ported and polished heads before, but i am by no means an expert.

that said, i don't know that it would do much good on these cars. (see my t belt destruct thread.) recently, i have the head off of my 944. i was thinking it would be fun to port/polish while it was out. then i got a look at it. the port is already so big, i don't know what to take off to make it breathe better. i am sure that ppl with the proper testing equipment could do some good, but i don't think that i can.

[Zero10]

These engines don't rev high enough to see any real benefit from a port/polish. I believe some have tried it, with very little to no benefit.
They breathe pretty well all things considered, IMHO, #1 breathing mod would be to remove the barn-door AFM, once that's gone, perhaps it would get enough air to see a benefit from a port and polish?

[fast924S]

Well, The head on a 944 NA is one of the biggest problems, hence breathing is a big problem and it doens help that we only have one cam and 8 valves. Zero is right the first thing I would do is get rid of the AFM and go MAP or MAF, If you port the head then you wouldnt be able to get enought air in because the AFM would be restricting it. I do think a proper P&P would help things out alot, you may loose some low end power but it would help mid to high RPM If done right I bet you could get 20-40hp out of the head. Since it seems like you dont want to spend alot of money, I would just get FR-WILKS POWER PROM 2 ,a good header and maybe a WEB cam and a throttle response cam for the throttle body. I think that setup would awaken your P-car.

P.S ZERO why wouldnt our engne benifit from a Proper P&P, I have seen V8's and V6's that rev to 6500rpm benfit from a proper P&P. I mean you cant make the port huge but you could make it better and more of a unrestricted flow in and out of the head.

P.S.S Also another problem with breathen is the Valve stems, If you ever have looked into you head the valve stems are huge and right in the way of the air flow, Some one could find a valve with a thinner stem to help breathing even more.

[ae1969]

Hey Slam,

Welcome to the board...... what part of the country are you from..

I am in the REPAIR season as well.

To answer your question unfortunately not much to be gained with a P&P at this point from the modifications you have done.

Save your bucks for the next maintenance item to pop up.

[Zero10]

P.S ZERO why wouldnt our engne benifit from a Proper P&P, I have seen V8's and V6's that rev to 6500rpm benfit from a proper P&P. I mean you cant make the port huge but you could make it better and more of a unrestricted flow in and out of the head.

P.S.S Also another problem with breathen is the Valve stems, If you ever have looked into you head the valve stems are huge and right in the way of the air flow, Some one could find a valve with a thinner stem to help breathing even more.

I have seen several people port & polish their heads, however I have not seen one who has done it and removed the AFM, so everybody that has done it has gained very little. I just believe that the bores in the head are already large enough to provide enough air for these engines. If they even revved to 7000 or 7500, I could see porting and polishing these heads providing a significant improvement, but considering the cost of having it done, I just don't think enough would be gained to justify the cost.

That is just my personal opinion, I'm not a mechanic or anything =)

[nynor]

have you seen the ports on these yet? they are HUGE!

[Warwood]

Porting and Polishing can mean a lot of things. If you are just talking about blinding the bowls and matching the ports you may not see a lot of improvement. If you are modifing the port by re-conturing them, there may or may not be that much you can do with out a flowbench. Its the port size and shape that determins flow, you enlarge it too much you can slow the intake charge velocity & hurt your low end torque. I also think that a high lift cam would be worth more than a porting job, but when combined w/ a P&P then there is the potental for a lot of power increase.

I agree about the finding smaller diameter valve stems would really help the flow numbers. While your at it though remember that will call for special valve guides.

Ok, lets go deep, while you have the head apart , there is a lot of room in that combustion chamber. I think 1.94 inch (49.27mm) intake valves are a possible fit, with revised valve seats. This is recomendation is based on the power levels that Fords get with that size intake valves i.e. their 5.0L crate motor (400+hp, 302c.i.).

Next step; Titanium valves and solid lifters, this will lighten up the valve train enough to raise RPM limit to 7500.

Ok now you have more ca$h into your head than you paid for you whole car.

Have fun,

[Slam]

Thanks, gents. It seems my suspicions have been correct. Alex, I'm in Wainwright, AB but used to live in Edmonton.

Of course, next question is how do I go about getting an MAF and replacing the AFM with it? Does this require changes to the ECU?

Slam

[fast924S]

no but you will need a signal messager to correct the readings so the ECU can understand it

[nynor]

where would i get solid lifters? and what other modifications are required to use them?

[ae1969]

Originally posted by nynor
where would i get solid lifters? and what other modifications are required to use them?

You need to redesign the camshaft housing to allow for adjustments. Hydraulic lifters do the adjusting........ no need to adjust valve lash etc...

With solid lifters its impossible to adjust with our present set up.

[fast924S]

I like the hydraulic setup, no need for adjusting and they are alot quiter, just replace your lifters with fresh new ones and then get some stronger springs and titanium retainers, that should be good for about 7,000rpm. As for bigger valves, its alot of work do install them and your gonna loose alot of low rpm power due to the drop in intake volacity. It all really depends on how much $$$$ you wanna spend and what your gonna use the car for. For a high end street setup, light port and polish, 3 angle valve job, Cam, header, MAF kit, Chip, cat back, and suspension work. That should make you happy

[Zero10]

There's a thread on rennlist about affordable MAF kits. I'm actually pondering making one, it seems possible enough that I'm compelled to make it =)

[Warwood]

Jon Milledge Engineering

Jon is one of the true 944 Gurus, from his web site:

Race Solid Lifter RS 304M2/280M-10 for 944/928
Best power band 5000-8200 rpm. 1300 rpm idle. Off idle lope. .595 cam lift In, .510 Ex. Race solid lifter, valve spring & retainer package required. Motronic will not work. After market engine management only. Bhp available depends upon tune of engine. No equivalent competitors cam. Used where lift is un-restricted but racing cam is allowed. Best results with unrestricted intake, fully ported cylinder head with larger valves, racing header.

He has other hydraulic grind cams that are not so wild, and only cost $650.
His web site is:
http://www.jmengines.com/