ported throttle body on LNF

[projectlnf]

im rebuilding my LNF that blew a piston ring land.. and while it is down i got the bright idea to start hacking away lol.. i ported the throttle body and i gasket matched the head and intake mani.. is there anything i should be changing int he DAL or MALT tables before i start this bad boy up and have issues and go insane?

[cobaltssoverbooster]

no see how it runs thats all and have tuning for the tb as there are no tables available specifically for the tb.

[projectlnf]

all right well ill let you know how it goes.. im finishing porting today on the intake manifold and the throttle body and then the car goes back together this coming week!

[hockeymandan2828]

Hey, how did this turn out for you? I ported / polished my TB, Intake, and gasket matched the intake side of the head. I think it helped, but also added an intercooler, phenolic spacers, and charge pipes at the same time. I guess I have no way of proving these things alone did anything, but it would be nice to hear if someone else also had positive results!

[cobaltssoverbooster]

since the tb is under boost at wot instead of potential vacuum due to airflow restrictions like an lsj this mod probably only netted a minute amount of. if i had to gues ~3 hp if any

[|V3nom|]

i dont think you can even "truly" port the lnf tb because its not a straight through design like most, its curved, so a normal port and bigger butterfly isnt likely going to happen.

[cobaltssoverbooster]

i used to make them on the lathe and mill

[|V3nom|]

i tried sending mine off a long time ago but they couldnt do it because it wasnt a straight through design. guess there is more than one way to skin a cat.

or just get a le5 tb and be done lol.

[cobaltssoverbooster]

you remove the plate, plate shaft, and tps senors. you can leave the bearings in as long as you clean it very well afterwards.
yes the bore is slightly offcenter but that doesnt mean you cant make it larger.

bolt it flange down into the mill and use a dial indicator to .0005" on a centering bit to make sure its centered on the origional bore.
put a adjustable boring bar tool on the mil and adjust it until it just barely touches then start making your measured cuts. once the wall thickness gets to as thin as you can have it in the spot where it was thinnest from the factory you stop.

measure the new bore dimension with a bore gauge. after you have 3 dimensions reporting the bore is perfectly round then you can smooth in the edges prior to and after where the plate seats. leave about 1.25" of fresh machined bore untouched so the plate has a standard surface to seal on and to help with tuning idle by allowing a predictable flow past a non varying bore dimension.

measure the factory angle on the throttle plate. chuck a 2" aluminum bar stock about 4" long into the lathe. machine down one side until it is flat. remove bar stock and put it in the mill using the new flat side as a leveling surface to make it stand perfectly vertical at 90*. tilt the mill head to the degree value of the throttle plate factory value and use an end mill to chop off metal in a bunch of passes until the pass has made a full contact surface cut on the bar stock. now without moving the mill head mark the center line of the new cut. find the center point of the center line in the opposite axis. now measure the center to center value of the factory throttle plate screw holes. cut the dimension in half and mark your hole location by measuring the halved value distance starting from the center lines center point you found before. mark the second hole in the opposite direction. drill then tap the two hole locations.

drill two holes in a plate of aluminum or brass to match the factory throttle plate. make sure the sheet has a circular cut out or you will destroy every piece you try to cut in a later step. i recommend a 4" hole saw with the centering bit removed and then find the dead center after you drilled it out. mark the location of the holes in the same manner as before to center the holes in the plate.

this is where it gets fun. insert your new angled bar stock into the lathe angle out towards cutting tool. tighten it down hard. spin check for centering. bolt your new 4" plate to the angle guide using blue loctite to help prevent the hardware from backing out and causing the plate to shift while cutting. back your cutting bit way out and make sure the area is clear. set to a mild speed on the lathe and test run without cutting to make sure parts wont go anywhere. now if everything checks out start at the farthest diameter dimension. if you cut a 4" plate start at 4.125" and slowly walk the lathe into the plate taking extremely small passes. if you take a big pass because the plate is thin and at an angle it will cause the plate to fold or worse be thrown from the machine causing harm. now you just keep making passes until you reach you new bored dimension for the throttle body housing. remove any burrs with a fine diamond file and reassemble the throttle body after cleaning and final inspection.


violla new ported tb! i used this method on porche 928, 996, 911, and 914 cars before i came to the ecotec world and if you know how to measure and operate the equipment nothing is ever impossible.

[oldskool]

why port the LNF TB when the LE5 is plug and play, and doesn't have that taper that the stock LNF TB has. If you wanted, you could port match the LE5 TB to the intake manifold and get everything flowing nicely. I'm running the LE5, and after some minor tweaks to the DALs, it's very friendly and drivable.

[cobaltssoverbooster]

verry nice! did it help you any?

[hockeymandan2828]

Ha, that is a lot of work for something like 3hp! I assumed the TB wouldn't do much for me, but since it was off I just figured a gasket match and mild port / polish wouldn't be a bad idea. Seeing that the TB is downstream of the turbo I did really want to spend too much time or money on it as the gains would be minor.

[oldskool]

verry nice! did it help you any?

It's hard to tell if there were any power gains (if there were, probably minimal), but the launching/off idle feels smoother to me, and it may be in my head, but i feel the ETC lag less...

Port matching the intake manifold will probably help a bit.

[projectlnf]

oookkk after months of trying and trying to tune that ported throttle body i gave up and put an le5 on it tonight.... lets just say...TEN times better lol throttle body 1 projectlnf 0