Okay so I'm planning on gasket matching my lower intake manifold and block tonight that way I can drop the motor in the car this weekend. Quick responses are DEFINITELY appreciated!

Some specs.
1987 fc 4port turbo
streetport
haltech e6k
720/1600
turbonetics 60-1

The dilemma I'm having is how to port the intake ports on the motor (should've done it when it was apart) without getting metal shavings in the engine.

My idea so far is to soak a paper towel in oil, stuff it in the intake port and dremel the pink areas all while the motor is tilted so the flakes will be more likely to fall to the floor. Pull the paper towel out with the remaining flakes. If anyone has a better way of doing this, suggestions, ideas etc.. please comment and let me know!

Pics.





I put pink paint around the areas that need work after putting the lim to block gasket in place. Luckily the block doesn't need as much porting as the lim.

I probably wont really touch the primaries as they don't need much work at all, but you can easily see that there's a lot of room for improvement on the secondary ports. Also, doing research on the forums I found that the texture should be rough as this helps mix the fuel/air better. Is this correct? If so I won't go smooth with the porting.

Thanks in advance guys!

 

Wow really? Where are all the gurus? rx7club is really going down the drain..

 

I would be nerve wracked with the idea that any small metal shaving got into the engine. If you are determined to give this a go I would make sure the area was absolutely sealed. Most likely a nice sticky tape that can take some abuse and leaves no residue and in front of that your rag. Before pulling it all out after completion grab a shop vac and get in there as good as you can and inspect for any potential breaks in your seal.

Some guys will go gently with a file just so they can control where the shavings go for the most part, shavings should stay outside the engine for the most part if you only file outward, this is a much more time consuming task obviously. Personally I would probably be tearing the engine back apart to do this, I am always paranoid of any contaminates infiltrating a new build.

Good luck!

 

Doing it by hand doesn't sound too bad! It's really not much compared to the lower intake manifold! Im tackling that now with stone bits but they create a lot of dust. I'm thinking tungsten carbide bits?

 

what do you need gurus for? you basically already answered the questions you had and decided to go ahead and do what you're doing anyway. you're simply seeking validation, and to be honest, it's a bit of a relief that no one gave it to you.


you answered it.

good job (and i'm not saying that sarcastically)

this applies, but it's limited. I think it applies more significantly to carbureted cars. to get the effect with this setup, you'll basically need to leave the casting flash in the runners (or cut grooves into them like I've seen some people do). that's probably a moot point now because the engine is ported and likely he runners have been "massaged". as a matter of fact, you'd be somewhat removing some of the "built in" turbulence" by port-matching.

you've clearly done research though, so along with the criticisms I've given, I would like to acknowledge that fact as well.

overall, I would leave well enough alone. the ship has sailed. the engine is already assembled. I doubt the possible gains are worth the possible risk.

 

Diabolical, the reason I was asking for gurus is because it never hurts to hear someone's ideas in tackling a job like this.

 

I really appreciate your input and although you're right about the ship sailing, I don't believe it has sailed until the motor is in the car. I am glad that 86svo chimed in and I will be putting the motor on a hoist so the intake ports face down, and then doing the porting on the block with a hand file. I thought that was a great idea. Although time consuming, it's better that having to worry about getting dust and flakes in the engine.

The reason I thought this was thread worthy is because I read of people doing this without even pulling the motor and I wanted to know if there were any tips!

Thank you for realizing that I did some research sir. Porting the secondary runners on the lim last night I liked the texture that the stone bits were leaving. Not too smooth at all. Although the gains may be minimal, you can see from the gasket that the secondary runners have some room for improvement and honestly, I enjoy tinkering with my car. That's probably the main reason that this happened. I will post some more pics tonight!

 

well, I've said what I had to say on the subject. I don't wish you ill and I'm a sucker for ported engines and photos. so post away when you're done.

using gravity to your advantage helps, but that said, I've been bitten in the *** by Murphy's Law enough times that I simply try to stay clear of that SOB!

 

Haha this is definitely sig worthy. Thanks for the kind words. I'll definitely post pics of the outcome.

 

Because not sure if serious.


Not only is porting an assembled engine a bad idea on an incredible number of levels, but gasket matching is also a bad thing.

But, hey, it's your engine, if you want to hurt flow at best or kill it before you even get to drive it at worst, go right ahead...

 

Peejay, why is gasket matching a bad thing? I can't see why smoothing out that area of flow would be a bad. Curious to hear what you think though!

 

You say it hurts flow at best but when I did my research I found that gasket matching increases smooth flow yielding hp gains.

 

Look at what you are doing. The gasket is larger than the runners, right? So a gasket match will make two short, rapid area changes in the runner. Runner goes bigger then smaller again. Area change means the velocity changes. The airflow slows down then speeds up. This wastes kinetic energy in the airstream and hurts airflow.

Remember that the air has mass, the hard part is getting it moving in the right direction, once it is moving then inertia will keep it moving until the port closes. That's how engines work at all despite having port closing times well after BDC.

Now, what IS beneficial is to have a roughly .040-.060" step-out. So the engine port is larger than the manifold port. The air will flow more easily into the engine than it will back up the intake manifold. This helps keep air moving in the right direction especially at lower engine speeds. Remember the hard part is getting the air moving in the right direction in the first place. Slow or stationary air is easier to get moving than air moving backwards...

I have never ever seen any engine builder worth a damn claim that gasket matching is a flow gain. Maybe opening up the whole runner using the gasket as a maximum, but that is not gasket matching, it's just porting.

 

I see what you're saying but where the lim meets the block is probably the most restrictive part of the whole system? Nearly a 90 degree turn right before the stream flows into the engine. I still have a hard time understanding how smoothing this out would have a negative effect.

Very interesting what you're saying. I have my dyno sheet from before so I'll be sure to head back and see what difference, if any, this has at all. I read a post by Aaron cake saying port out the irons an lim to match the gasket. I doubt he'd be saying that if it yielded a negative outcome.

 

I can't speak as authoritatively or as eloquently on the subject of airflow as Peejay (or a few other members here). I am still a student - a humble student - of airflow. what I will say is this though: I've come to find that MANY things that look like they SHOULD be with airflow, actually aren't.

at the end of the day (and since you've already started it, I know it's too late now, but) listen to Peejay. do some more research WITH an open mind.


as far as port matching goes, I used to do it, but I quit doing it maybe 9 to 10 years ago. actually let me clarify, I quit doing it with my rotaries 10 years ago, I prepped the manifold for my Audi 2.7TT maybe 2 years ago and that included a gasket match. anyway, I've seen where people have charted minimal gains (mainly turbo piston engines) and I've seen many of the arguments against it - including the points Peejay brought up. the arguments against seem to make more sense though.

 

I am approaching this with an open mind. I haven't touched the block just yet. I understand the whole velocity concept but that airflow is gonna slow down regardless, due to the sharp turn into the block and the turbulence that is created. I'm not sold that smoothing out this area will yield negative effects. Air is a fluid correct? So why not make the path smooth? Because I will slow down the velocity that is already massively slowed down? Okay.

It's not like I'm making the ports 5 times bigger than they were before.

 

i have an idea... scrap the idea of porting the assembled block.

take a long sheet of paper, cut it to match the block ports and overlay that to the LIM and port it to match your current block openings.

is it worth possibly getting debris in the engine for that <1% more? opening up the LIM will also cause the power to shift again higher into the RPM band, which can have negatives. it is usually better to make power lower unless this is a race engine(and no, a race engine is not always ideal even though everyone likes to think they are speed racer).

smaller ports= more velocity but less volume. more torque but less usable RPM range
larger ports= less velocity but more volume, higher usable RPM range but less responsive outside of the peak power range

larger ports for higher revs or bigger turbos. stock ports for narrower power band with better response, for stock turbos.

stock ports are in fact borderline large enough for most setups, even highly modified with proper turbo sizing.

 

The problem isn't that the air slows down so much as air, like most things, doesn't like to change direction.

Also bear in mind that you are not smoothing anything down. You will be making an area change, not fixing one.

 

You're right peejay. I will make sure the manifold isn't ported out as much as the block to prevent reversion.