porting a spare intake manifold?

[VinceSez]

I was planning on buying a used intake manifold, but I wanted to know if there would be any gains if I were to just have the intake manifold ported and installed on my car? I know that there has been numerous posts about this and I've searched, but none has really answered my question. What type of work could I have done to a spare intake manifold at a machine shop that would give me some gains? I'm kind of new to port and polishing.

[KADreams]

I have no answer to your question, but I would look into extrude honing.

[tonynalli]

if there are casting imperfections then you can port it.but i dont think there is anything that you can do to make and gains out of it...make a custom made minfold on it instead

[JNM240]

You can match the intake runners to the gasket, enlargening them just before they meet the cylinder head. You can also remove the butterfly (swirl control) assemblies, but i havent done this, so im not 100% sure what needs to be done for that.

[DjPantsSpecR]

you would see gains from porting or extrude honing it. extrude honing is obviously your best bet as stated previously, but you'd be better off spending that kind of money on making a new intake manifold plenum and shortening the runners.

I'm including this because its reputable and good info, from http://www.grapeaperacing.com:

"Your goal with any port modifications shouldbe to get as much flow and velocity as you can withas little restriction as possible. When working on aflow bench, pay close attention to how much metalyou remove and how much the port flows. If youhave a 100 cc port that flows 100 CFM, then youmodify the port by grinding 5 ccs of metal away andthe port now flows 110 CFM, you gained flow andvelocity (a good thing for a street engine). If yourmodified port flows 103 CFM, you gained a little flow,but lost velocity.

You will need to cc the ports often andmeasure flow often to get good results. If you don'thave access to a flow bench, it's best to remove aslittle metal as possible. Most pocket porting jobsgive very good results when less than 5 cc's of metalis removed. More than that, you need a flow benchto see if what you're doing is helping or hurting."

also this about intake runner length tuning

"Forsmaller cams in the 270° range, subtracting 20° fromadvertised duration will give better results. Theformula for optimum intake runner length (L) is:L = ((EVCD × 0.25 × V × 2) ÷ (rpm × RV)) - ½DWhere:EVCD = Effective Valve Closed DurationRV = Reflective ValueV = Pressure Wave SpeedD = Runner Diameter"

that gives the runner length for helmholtz resonance as a function of RPM and cam duration. it is useful because it contains runner diameters which would be affected by porting, and you can choose which rpm you want to make optimal power at.

so do both, get a port, but no more than about 5ccs or less, and get a sheetmetal intake manifold made. i've already drawn out the plans for mine and the entire build cost shouldn't be any more than 25-30 bucks. or buy a decent one for almost 600 dollars, or get a machine shop to build you one for much less than that.

[spider_slayer]

wouldn't regular old sheet metal be rather prone to getting ridciously hot compared to the stock intake mani?

i am curious about the custom mani and have seen it done many times on F/I probe gt's. jsut never seen it on the ka. have any sketches or measurements yet?

[tonynalli]

there are a ton of people that have made their own intake maifolds..just seach a little i guess

[DjPantsSpecR]

stock intake manifold has got to be in the 200-300 degree F range. On FSAE racecars, sheet aluminum is enough for this temperature range. and every decision on this car is made very carefully, and by several engineers-in-training, such as myself.

they literally use off the shelf allen head bolts, liquid rtv, and .050 in T-6061 aluminum. and the general rule of thumb is to make the plenum twice the volume of the motor. we use a 1356 cc plenum on our Yamaha R6 motor.

i have sketches, it couldnt be easier to make. literally a plate that you weld on to the cut intake runners. drill holes in this plenum for mounting the sheetmetal plenum you intend to make. you can address this from many routes, but a square box works, or a round top box, or a rounded angle cut box, or whatever you can make fit. you then cut a hole on the front for whatever size throttle body you want to use, and then you need to figure out where to ground the battery and route vacuum lines, coolant lines, egr, master cyl, etc. its starts to turn into a big job after a while. but this is cheap power and i do not discourage you from doing it

[drifterz73]

i have sketches, it couldnt be easier to make. literally a plate that you weld on to the cut intake runners. drill holes in this plenum for mounting the sheetmetal plenum you intend to make. you can address this from many routes, but a square box works, or a round top box, or a rounded angle cut box, or whatever you can make fit. you then cut a hole on the front for whatever size throttle body you want to use, and then you need to figure out where to ground the battery and route vacuum lines, coolant lines, egr, master cyl, etc. its starts to turn into a big job after a while. but this is cheap power and i do not discourage you from doing it

can you email pics of this sketch you have. [email protected]

[drifterz73]

stock intake manifold has got to be in the 200-300 degree F range. On FSAE racecars, sheet aluminum is enough for this temperature range. and every decision on this car is made very carefully, and by several engineers-in-training, such as myself.

they literally use off the shelf allen head bolts, liquid rtv, and .050 in T-6061 aluminum. and the general rule of thumb is to make the plenum twice the volume of the motor. we use a 1356 cc plenum on our Yamaha R6 motor.

i have sketches, it couldnt be easier to make. literally a plate that you weld on to the cut intake runners. drill holes in this plenum for mounting the sheetmetal plenum you intend to make. you can address this from many routes, but a square box works, or a round top box, or a rounded angle cut box, or whatever you can make fit. you then cut a hole on the front for whatever size throttle body you want to use, and then you need to figure out where to ground the battery and route vacuum lines, coolant lines, egr, master cyl, etc. its starts to turn into a big job after a while. but this is cheap power and i do not discourage you from doing it

please email [email protected]

[DjPantsSpecR]

you e mail me pimpin and ill do what i can. someone wrecked my car, so now i'll actually have the money to make my own, but im getting it welded at a machine shop.

didnt mean to ignore you, but i will help out

edit: if you didnt know you could click on the names to get the email address, mine is [email protected]
Modified by DjPantsSpecR at 8:26 AM 3/16/2006