So i am rebuilding my engine. It's a 13b from a 85 GSL-SE. And I pulled off my intake yesterday to find out that my 5th and 6th port sleeves have not been moving at all. The vacuum line was disconnected from the actuators. Would there be any harm in just removing the sleeves and leaving the ports open all the time?

 

Remove the sleeves and actuators and block off the holes in the intake manifold.

 

The sleeves help with keeping low-end power and mpgs. Removing them will result in a noticeable lose of torque, and slightly sluggish acceleration. If you get them working, you will be happier than trying to deal with removing them.

Maybe this will help; read this. It has alot of helpful information.

Hope I helped!

 

Yes partial throttle(<25%) will suffer, but you will make more power everywhere wide open. Do you want to run better lugging around a parking lot, or where it really matters?

 

Not true, when closed they raise air velocity helping with low end power at any throttle position / engine load. The point when they should open changes with engine load but how they work and the fact that they work never changes.

and where dose it really matter? Unless you're engine is in a fixed speed prop plane or you have a CVT peak power is useless for every thing but making you're E-***** bigger.

 

There's more to power than just velocity.


Anywhere outside of a parking lot. Have you ever driven a car without sleeves and actuators? My stock S4 motor blew tires off if I put the hammer down at 1500rpm in first and had more response in fifth on the highway than the same motor with working sleeves in a different car.

 

True, But it is still a fact that if you have them and they are closed when they should be velocity will be boosted AND the fact is that you WILL make more low end power. The only time this is not true, you have done enough work that you should have used a 4 port and the argument is moot any way.

I have run S4 and S5 blocks with and with out aux ports sleeves, with S4 and S5 NA and S4,S5,S6 and RE turbo intakes, Modified and stock, custom, Carb and EFI, I have run engines with a mix of S3-S6 and RE parts, I have done stock ports, street ports, half and full Bridge ports with S3-S6 and RE blocks and combos there of.

Why is it you like to dispute what I say? lol is this going to be the new Half Bridge Potential thread where you keep calling me a dumb **** and cant back up any of you're arguments?

Look its real easy, aux ports and vdi work and they do so well. I may still have dyno charts from 8 years back. I had my aux ports on an rpm switch, Did a pull where they never opened and where they opened at about 1000 rpm then i set the switch to have them open where the two lines intersected. If I can find them I will scan and post them.

 

Not so much the sleeves, but on a decently modded engine, the actuator rods do act as a restriction to flow. Removing the sleeves, TIG'ing the holes closed, and grinding flush resulted in a requirement for more fuel in almost all usable driving loads. This means more usable torque across the entire curve, even in part throttle.

As for the whole low-end power argument... I think its pretty inconsequential. These cars have gears. You don't buy a performance car, spend a bunch of money on modifications, and then complain when your car has a few less lb-ft below 2500 rpm but more power everywhere else.

Again, this implies ported engine, exhaust, etc etc. Removing them on a stock engine is retarded.

 

You must have some pretty shitty tires, or really low performance expectations.

 

Removing the sleeves and actuators is not the same as just having them open, you seem smart enough to know that. See below.

The stock engine with exhaust benefits from having them out as well.

 

i was looking at the actuator rods but i can't get the screws off that are on there. but if i have to weld it shut i'll just grind them off. and I am proting the engine and putting headers on as well so i think i'll have sufficient mods to go ahesd and do away with them.

 

The OP did not talk about porting, and this takes me back to what i posted "The only time this is not true, you have done enough work that you should have used a 4 port and the argument is moot any way." But then again my feelings are that porting should be done starting with an RE or at least a 4 port keg as there is far more potential.

Now this is the part that makes me sick of the forum, I need to add a disclaimer to this.
note I said "my feelings are" Also I do know that some feel it is worth the time to port a 6 port keg and i also know that some have done very well doing so.

Stock block? keep aux ports and vdi working.
Street port 6port ? depends on a lot of things but for the most part keep them.
any thing bigger ? I would never use a 6 port block but yep at this point you should not have the stock intake letalone aux sleeves.

as far as not having the sleeves and just having them open. Did i not tell you I have run damn near any set up with or with out damn near every pre MSPI 13b induction part? Yes there is a difference and it was 3 hp in and open vs out with the rods out as well on a small street port with S5 irons. 3hp, hell thats heat soak in the spark plugs, air temp change, what ever.

Scathcart,
Yes i did complain... so I put them back in. That was a long time ago, I no longer use 6PI blocks. This is also why all three intakes that I have made that have stayed on my car for more than a week have had a divided plenum for primary and secondary ports with a progressive TB, smaller diameter/longer runners for primary and where variable length on both primary and secondary runners. I will take my low end, 26+ mpg mixed driving and 260 RWHP and enjoy every last bit of it.

 

I only found the chart for closed.... but I found this.
Link with open closed dyno runs
Mine where close to this. Note that this is not some little oh well amount of power its over 10% gain in torque for most of the area under 4k rpm, so 10% more power over about half the power band. Again once you start porting you change the dynamics of the engine but they still prove helpful some times more so than on a stock engine until you start getting into mid/high overlap *as in half/full bridge port*

 

Dyno's, Mazda engineers, engine tuning, accelerometers, and timeslips all disagree with you.

Stock engine with an intake filter, stand alone RB header, straight pipe and borla catback exhaust. Swapped out working stock LIM for LIM w/ rods removed and holes welded closed. Retune resulted in a decrease in requirement for fuel below 4000 rpm (meaning the engine made less torque), and zero change above 4000. Engine logging saw no improvements in acceleration time for fourth gear pulls from 4000-8500, accelerometer registered no change.

Removing the sleeves does not make an unported engine any more powerful. Testing doesn't lie.

 

I've also built 4 port N/A engines, with great results. But that doesn't mean that when someone asks me to help modify their existing modified 6 port engine that I force them to rip it out and install a bridged 4 port. If I can squeeze improved usable power out of an existing set-up, I'll do it.
I was adding 3-5% more fuel on a large street-port with the actuator rods removed, which is more than 3 hp, so I can't comment on your combination.
I also can't comment on your driving style. Personally, if I were worried about my performance and fuel economy at 1500 rpm, I certainly wouldn't be using this engine platform.

 

I agree with you for the most part, I just don't conceder the 6PI to be a viable high hp NA engine and don't see the point in any thing over a street port on a rebuild. I tend not to like the "early open" street ports much as well, the drivability of an early open street port is not that much better than the bridge ports I've been building for the past handful of years. I would also never build any thing past a street port on used housings, at that point what is the cost of some good used 4 port irons?

as far as fuel economy, Hey if peak power is the cake and a wide power band is the icing what is wrong with having strawberries on it too?