Qtiger,

I may be a newbie to this board but I just want to clarify some head mysteries. Porting does not refer to removing as much material as possible. It refers to reshaping and selectively removing only that material which impedes airflow and velocity. "hogging out" ports without regard to shape is about the worst thing that you can do to a head. The reason many people don't get good results sending their heads off for a "port and polish" is that number one, Honda/Acura did a fantastic job to start with, but more importantly, number two, most people haven't got a clue what a 4 valve head wants in the way of porting. Most 4 valve stuff I have seen is just a port match (which ain't much on a Honda/Acura) and smooth out the ports with cartidge rolls.

I would say that 75% of the heads I have done in the past has been domestic style 2 valve heads, but the 25% of 4 valve stuff has been much more challenging and for the most part untapped as far as potential. Most customers just want that quick and cheap "shine job" then want to bolt on a $3000 turbo or supercharger. The analagy that I like to use is that of trying to force more water through a hose by just putting a bigger water pump at the beginning (ie, turbo). If you replace the hose (port) with one that flows more water (air/fuel), then you will get significantly more output with the same water pump pressure (boost). Believe me, there is a LOT to be gained by getting the heads done right.

 

Did you read my post?

 

Methinks not.

Generally, on import heads, there is no need to have a P&P done anyways as their is more potential risk than gain if the work is done by someone inexperienced, and the extra few percentile of power will not make a difference except in bragging rights on the dyno, or in higher teir drag racing.

 

I read the post again, and I still contend that porting IS beneficial. The problem again is that most people try to port a 4 valve head like a 2 valve head and they are totally different. The shine job I referred to is what most people end up with and gives almost no benefit. I have checked out the difference on my flowbench with a B18a head and there is hardly any measurable difference in just polishing the walls and gasket matching versus a stock port. I fully agree that there is a lot of risk out there or at least minimal benefit for somebody with no clue as to what they are doing, but I'm just saying that there are some people out there that know how to work on a 4 valve head and make good power. I doubt that the "all motor" Hondas/Acuras out there are running on unported heads.

BTW, I have to say I dig this website, lots of good info here. I stick mainly to the engine side of things but am always looking to see what the rest of the combination holds. I hope some of you were able to get to the PRI show in Indy last week. Tons of new products out there for the Honda/Acura crowd including a new edelbrock complete turbo system for a D16Y8. Have fun.

 

Lemme just say that those people are more heavily in the minority than the majority. I agree that you can do some serious help to an engine by porting it, but on the other side of the coin, I've seen an engine head go from good to better, to horrible, all in one session when the guy didn't know when to stop. :dunno: Like I said earlier, the people that want a little more power, or bragging rights go for ported heads. Right now all I'm running is a port matched intake manifold with my webers on a built lower end, making an extra 50 HP. Looking to put in a cam soon, and from there, if I find that the head is limiting the potential of the cam I'll see about getting the head ported. Until then, I'm happy with my quick little car that puts Si's to shame and still gets over 30 mpg.
Thanks, we kinda delve into everything. I'm the original mod of the forum, and have dealt with just about everything, 2-stroke, diesel, 4-stroke, carburetors, multiple carburetors, ITB's, turbos, methanol tuning, nitromethane, etc. Qtiger and Mike [fatbooty] are the former teg pilots, so they're the B-series obessors more or less, and Inspyral joins me in the D-series ranks, but more on the do it yourself gizmos, cheap parts online and turbo side.

 

Okay, I'll rephrase. I tried to say that the term 'Porting' is overused and generally not true in an import application. I don't know of anyone who actually ports Honda heads. In general, you're in there removing casting flash and smoothing stuff out, changing angles, etc.

The problem is that "most" (Generalizing) domestic heads aren't made with the same amount of precision and expertise as "most" import heads. Honda in particular has been in the business of making cheap, lean burning, efficient engines almost since its conception. That was their marketing advantage over domestic manufacturers and sole territory for probably 25 years.

In that same time period, domestic car companies mainly ignored these issues. It took the oil crunch of the 80s to convince them that they needed to change their ways, and they've been playing catchup ever since.

So on domestic heads, particular older domestic heads with some gentle (or not so gentle) massaging and a standard 30-45-75 3 angle job, you can squeeze out some power even if you have no idea what you are doing. This created a trend, and some attitudes of 'these are the best ports/angles/way to do this' and unfortunately when applied to an import head, bad stuff happens.

These machine shop P&Pers are IMHO, in the majority of shops offering port and polish services. Quite frankly, I do not think I would let anyplace that didn't specialize in Honda heads lay a finger on my head.


I agree that good gains can be achieved via a quality P&P job, but even from the best in the industry we only see around a 10% flow gain.

10% gain for around a thousand dollars is pretty steep. Not to mention shipping costs and downtime.

I mean, that's half the price of these:



My latest project. Now that winter break is here I'll finally have time to get her running.

 

I have to say that from the factory, the Honda heads really are a fantastic design and on the flowbench the B heads I've tested really kick butt over any factory domestic small block v8 ever offered. You're absolutely right about the domestic stuff being choked up in stock condition. Lets just say that as with almost every head I've seen, the areas on Honda/Acura heads that produce the most benefit in reshaping are the ones that are hardest to access. That is why you usually don't see a whole lot of benefit in anything but a full port job.

Looks like a nice intake, qtiger. 1stgen, most projects I've done have been carb and actually one of the engines we built at the last shop I was at before going out on my own now holds the NHRA national record in comp eliminator F/ED with a 4 cyl - 2V and 4 Webers so I feel your pain in getting them to really work right. Have you ever looked at converting to a slide valve carb like a Lectron?

Glad to meet you guys. I'll be checking back often.

 

You should flowbench an S2000 head somtime.

Take a peek at this:

 

I've seen that. Smokin! That's over 310cfm at 28"H2O!

 

No I haven't for the simple reason that my car is still my daily driver and I've driven high-strung carb'd engines enough to have a fairly calibrated feel for throttle use to keep intake velocities up, whereas I've found with most slide valve carbs, the technique is much different, and not really suited to my style on the street. Not only that, Webers look schweet