wastegate/mbc/whatever

i have a 91 eclipse gs-t, and this guy had a 91 talon tsi. he said he capped off the vaccuum hose going from the turbo to the wastegate(stock setup), and said it added 2-3 lbs of boost. I told him that its dangerous, the boost could spike up too high because the wastegate wouldnt be opening. He said that "thats theoratically true, but the manufacterers wanted a safe and economical car, therefore they toned it down a little by putting a wastegate on it, a wastegate that wasnt really needed". so i went to home depot and bought an open/close shutoff valve and two 1/4" flanges for either end, to splice the vaccuum hose into. that way i could try it, if it looked too dangerous i could just leave it open, or i could even have a little type of boost controller. then i decided to ask u guys about it first. What do you think about this? Could i spice this shut-off valve into the wastegate vaccuum hose, shut it, and safely gain some extra boost? i still have the stock setup pretty much, as far as turbo, wastegate, and hoses, so what do you think?

The wastegate IS needed because a 14b can flow a lot more air than a stock car can handle. I would have thought capping the boost source for a WGA would stop it rather than just adding a 'few psi' (Doesn't he have a boost gauge?).

Your valve is almost a basic boost controller, but not like an up to date style, so it might be interesting trying to adjust it just perfect. MBC's really aren't that expensive, but see how that works with your aftermarket boost gauge.

that guy is a moron.. dont listen to him.

what you are doing though is a manual boost controller. it is safe for your turbo/engine as long as you have no leaks in what you put on. i made a MBC the same way on my Talon TSi AWD

remember, stock boost guages are inacurate.. go back to home depot and get a psi/kpa air pressure guage(a good one from there would be a 0-60psi guage). make sure you dont go over 16 or 17lbs of boost or you will tear up your components over time

hope my info can help, ask more questions if ya have em... its the only way to learn :p

*EDIT* we replied at the same time :smile:

JoeWagon:
I would have thought capping the boost source for a WGA would stop it rather than just adding a 'few psi'


what exactly does wga mean, and how could that stop the boost?

anyways, if i did the mod, how could i safely check it out? i have an autometer 30boost/30vaccuum boost gauge, so i could monitor how high the boost gets. what should i do, drive around normally and see how it is, then get on the expressway and punch it a couple times and see how high it goes? I have 147000 miles on the car, how high of a psi level could my car handle?

i read this one post from dsmtuners.com(i think..?) about a DIY mbc, and he mentioned drilling a small hole into it to release pressure, but for some reason the hole doesnt hurt anything until the boost gets really high, or something like that, i asked him in an email a few months back, but dont remember what he said. If I could get up to like 14-15 psi, or more(im running 11-12 right now) that would be pretty good...watcha think?

You need an aftermarket boost gauge, the stock one is a joke. Without the wastegate opening the 14b can boost well past 22 psi on a stock motor potentially doing a lot of damage.

The little valve you got will work fine, it won't be real precise but it will let you control boost, one thing.... don't remove any of the stock vacuum hoses for the wastegate, one already has a brass restrictor in it and you'll end up with less boost. The best cheap setup is a combo of a restrictor like you got and a bleed valve, between restricting and bleeding off the signal to the wastegate you can get good control for a dirt cheap price. I still use my $30 homemade setup on my 10.5 sec Talon, it's fully adjustable from the cockpit.


LOL...FWIW Years ago one of the first mods I did was to simply put a zip tie on the wastegate hose, I got an aftermarket boost gauge and played with the zip ties until I got a reasonably well controlled 18 psi of boost. Stock the car ran 14.8, with this zip tie and a K/N I ran a 14.4 with no other mods.

WGA = wastegate actuator

how did you get a home made boost controller to the cockpit of the car without alot of inacuracy? thats a lotta hose for your vacuum to travel :D

oh man oh man im gettin kinda psyched about watching the boost gauge go past "11 psi"...if thats possible.......oOoOOOeEEeeE!!!

this is how i blow all my paychecks, listen to one guy in a parking lot, then i come here and read posts and see pics of cars, now i wanna go out and buy a bunch of stuffand be running 10's by midnight, or bust.



thats what the guy who made the DIY MBC thing told me, that the little hole he drilled in it was a bleeder...this valve i got has enough room for a bleeder hole to be drilled in, ill take pics of it in a sec

WGA = wastegate actuator

how did you get a home made boost controller to the cockpit of the car without alot of inacuracy? thats a lotta hose for your vacuum to travel :D
Dual control. I have a small restrictor valve under the hood that I can set for a range of boost. The in the cockpit one is a bleed valve which comes after the restrictor one. I've used this setup for years now with many different turbos. When I had it on the 14b I could adjust from 12-22+ psi within 1.5 psi accuracy. It fits perfectly in the hole where the cig lighter was.

oh, after 15psi you are just messing shit up under the hood. i wouldnt recommend it if you are barely over stock

WGA Wastegate Actuator. The brass colored part that the hoses go to.

96tsi, yeah I took forever posting because I had to look at Kevin's RKO post to remember if capping boost source would increase or decrease boost (if the boost source opened or closed the WGA in essence).

The only reason that it might be harder to control boost is that the new MBC's are a different style. Ball and spring type valves effectively cap the boost source until a certain pressure is reached. Then the ball comes off of it's base and it let's the WG open yadda yadda, so it's precise as to when it opens. YOURS will restrict only a certain boost no matter how many PSI is being put through the valve. No biggie, like 10.5sec said, they still work.

Just get on the throttle and see how much boost you build while the valve is OPEN. Should be like 7psi or something low like that, can't remember 1g WGA spring pressure. Close the valve a little and go again, keep going until you reach the desired boost level. You are just restricting the boost like 10.5sec did with zipties back in the day. As to what boost to run on a 14b, I wouldn't know... I would have guessed 18 hits fuel cut.

Dual control. I have a small restrictor valve under the hood that I can set for a range of boost. The in the cockpit one is a bleed valve which comes after the restrictor one. I've used this setup for years now with many different turbos. When I had it on the 14b I could adjust from 12-22+ psi within 1.5 psi accuracy. It fits perfectly in the hole where the cig lighter was.


damn thats a good idea. talk about saving some effort and money

all it takes is a poor man and a little thought to come up with the best cheap mods :D :D :D

oh, after 15psi you are just messing shit up under the hood. i wouldnt recommend it if you are barely over stock
If you run 93-94 octane gas 17-18 is safe long term on a 1G. The stock F/P & injectors can easily handle that on a mildly modded stock turbo setup.

oh no man, the "that guy is a moron" wasnt referring to you, i was referring to to talontedEcLiPsE's friend in his post

heh i put an edit at the bottom of mine after i realized i wasnt the first reply to him :D

. As to what boost to run on a 14b, I wouldn't know... I would have guessed 18 hits fuel cut. Depending on the car and temp outside, yeah around 18 you might hit it. Take the lower honeycomb out of the MAF and cut the divider wall out of the lower oval portion and you'll push fuel cut past 21 psi on most 14b cars.

damn thats a good idea. talk about saving some effort and money

all it takes is a poor man and a little thought to come up with the best cheap mods :D :D :D
LOL! Yeah when I first started modding years ago I was a man on a mission, I wanted to go as fast as possible with as little money spent as possible. I live only 15 miles from the track so I could do little cheap and freebie mods and continually track test each one to see if they were helping or not. I learned a lot that way.

yeah ive already done some of those freemods...

-k&n filter
-hacked the airbox
-took both the lower honeycomb and MAF restricter circle thing out
-took out a plastic vent thing in front of the air filter and right behind the headlight
-drilled into the boost solenoid(never noticed any difference, good or bad, from this...probably did it wrong, was too scared to mess something up)
-cleaned out the intercooler with gasoline and degreaser

-i run usually 93-94, always 94 unless i cant find it
-autometer boost gauge
-stock exhaust pipe to an aftermarket muffler

http://files.automotiveforums.com/gallery/watermark.php?file=/503/81661Pict0010.JPG
Ok, that valve looks like it's going to be too big to give you any control. You're better off with a small fish tank valve or get a small air tool compressed air pressure control valve, you'll be able to do some fairly fine adjustments then.

10.5 sec u sure? i payed $9 for this stupid thing and its too big? i think the picture is bigger than the real thing though..

ur sayin i couldnt just open it a little bit and it would be fine?

Here's a little 1 I used to fool with before I settled on my dual setup. It is a bleed/restrict combo valve, it worked fairly well but wasn't as precise as my dual setup is.

http://my.voyager.net/~wcfields/HPIM0857.JPG

it will work just be very carefull when you turn it to get more boost, little too much then your are spiking 20+pounds of boost

BE VERY CAREFULL when you move that valve

you should post up some pics/diagrams of your dual setup for me 10.5 :D

10.5 sec u sure? i payed $9 for this stupid thing and its too big? i think the picture is bigger than the real thing though..

ur sayin i couldnt just open it a little bit and it would be fine?If those are 1/4" fittings that valve has a fairly big bore and ball inside it. Your control is going to be near impossible as a tiny adjustment will change your psi by several pounds.

ok im gonna give it a shot...if it doesnt work i can just put a new vaccuum line on(i have em all over my trunk)

heres what ill do

put the valve on, and then open it all the way.
drive the car a little bit and see what boost it gets
adjust the valve and repeat until desired boost levels.
add hp to taste

is that the right way to go about doing it? not to sound like an idiot or anything, just wanna be EXTRA careful with what happens, this is my only car and i cant afford to fix a blown something or whatever could happen....but im too addicted to modding to NOT do it lol

well 10.5seconds just shot that idea out of the water...guess ill wait and find a fish tank valve

as soon as i find the pic of my MBC, ill post it up here.

i used a small air valve, pretty clean setup and it doesnt look like trash (most home depot jobs do)

you should post up some pics/diagrams of your dual setup for me 10.5 :D
Here's an old pic of the cockpit control when I first put it in. Note the little red ring, when you lift it up it locks the dial so your settings can't be accidentally changed. If I get some time to get over to the car where it's stored I'll take some new pics and post a diagram. Might be a while.

http://my.voyager.net/~wcfields/HPIM0859.JPG

man i just wanna try it to see if it could have some kinda positive effect...

ugh imma try it...u live n u learn

plugged it in using extra vaccuum hose so i didnt have to cut anything.

drove around on a 40mph rode and punched it a couple times. got good results and seemed pretty quick, it got up to 15psi, i was too scared to go WOT. tomorrow ill try the expressways on the way to work.


just a question....if the boost gauge says 15psi, and its hooked up correctly and everything, that means that there is 15psi going to the intake and nothing higher right?

Where is your boost gauged tapped into? If you overboost you'll hit fuel cut, so be ready for a big lurch! LOL!

your boost will spike occasionally over what you have it set too, no big deal as long it doesnt stay that high

well just call me overboost.com.....lol jk

i tapped it into the...i forget what is called, its right up by the master cylinder...its where everyone says to do it where its most accurate...i kept the line as short as possible, and mounted the boost gauge in place of the recirculate/fresh air knob. ill keep it careful tho

just a question....if the boost gauge says 15psi, and its hooked up correctly and everything, that means that there is 15psi going to the intake and nothing higher right?

Probably, I assume you tapped the FPR solenoid - to - Manifold line. Even boost gauges can be inaccurate, don't be so worried about exact pressures right now. If you hit 25psi you might blow an intercooler pipe, knock a lot, etc... but if you aren't hitting fuel cut, you aren't flowing too much air (on stock injectors of course). How much boost is in the intake manifold really doesn't matter that much. After you start modding you will watch knock, and if you don't see any, it doesn't matter if you are boosting 30psi. A llittle much for a 14b but you get the picture. If you had no knock (race gas, propane injection) you would be turning up the boost to before you DID.

You might want to consider a few cheap tricks to keep things a bit cooler to prevent knock.

Run 1 step cooler plugs. (Make sure your wires are good too.)
Block off the Throttle body coolant lines.
Block off the EGR with a block off plate.
Flush and fill your cooling system real good, put in a 1 step cooler thermostat, use a 50/50 mix of antifreeze/water and add some Water Wetter brand cooling system enhancer to it.

A good freebie is to bump the initial timing setting. folks say this does nothing but I've track proven it to add 8-10 HP. Sure the ECU sets timing, but it uses the initial setting for reference, bumping the initial timing a bit insures full timing, these motors like a lot of timing anyhow.

A properly running 1g with all the freebies, minimal mods, stock exhaust running 18 psi boost can easily run 13.5@100 in the 1/4 mile, a huge improvement over the 14.8-15.1 stock times.

Block off the EGR with a block off plate.


I thought I read somewhere that on turbo cars blocking off the egr will cause a very very slighter chance of knocking. I can't really remember it correctly though.

That's because you are making more power, and not bunny friendly emissions. EGR is total BS, it literally steals combustion space from the real A/F mix.

About the TB coolant lines, I was reading about how it didn't affect anything... I don't know what they said about it back in the day, like in the digest? Somehow, air travelling at 100mph through the TB doesn't seem like it would gain much heat per lb/min.

That's because you are making more power, and not bunny friendly emissions. EGR is total BS, it literally steals combustion space from the real A/F mix.

About the TB coolant lines, I was reading about how it didn't affect anything... I don't know what they said about it back in the day, like in the digest? Somehow, air travelling at 100mph through the TB doesn't seem like it would gain much heat per lb/min. It's all the little things that add up, why have 190 degree water heating up your throttle body when you're doing cold air intakes and other things to keep detonation low? And it's so simple, take the 2 hoses off and screw a bolt into each hose, 2 minutes and you're done.

Blocking the EGR is a very effective mod and it lowers chance of knock due to cooler intake charge temps.

Run 1 step cooler plugs. (Make sure your wires are good too.)

A good freebie is to bump the initial timing setting. folks say this does nothing but I've track proven it to add 8-10 HP. Sure the ECU sets timing, but it uses the initial setting for reference, bumping the initial timing a bit insures full timing, these motors like a lot of timing anyhow.


in the car now is ngk bpr7es spark plugs. i have a set of bpr6es laying around, should i use those? also, what size should the gap be?

about the timing, u mean adjust the CAS a few degrees? how much should i adjust it?


anyways, drove to and from work today, o man it was incredible. hit 16 psi at WOT in 2nd, 3rd, and 4th, but it creeped back down to 15psi, which is still good. i got on the expressway this morning, not very many peopel around, going about 50-60, downshifted to 3rd and punched it, got to 4th then 5th, in a few seconds i was at 100-110 or so, a big increase from before. OOOOOO!! since im a tech at a mazda dealership, im gonna get coolant and enhancer and flush my system on thursday or friday if i can, and my boss said he would give me some of these different BG cleaners/conditioners to use. any other suggestions for what else i might be able to do, let me know pleeeease lol, thanks for all your help so far though

make sure your brakes are good lol. seriously one thing way too many people overlook is how they're gonna stop from 100+ mph. stock brakes will heat up and then they aren't as effective. bigger rotors, pads and calipers should be part of your upgrade path. going fast is fun till you get to the point where you can't stop the car

yea, i was gonna mention that too, whats a good name to get?
money isnt TOO much of an issue, so good quality and life are a must.


one time me and a lancer evo were on the expressway and we started goin at it. at about 130mph we caught up to traffic VEEEERRRY quickly, and i knew my brakes were not gonna be able to stop in time, i had to swerve around the traffic until my car reached civilized speeds, but still it scared the crap out of me.

in the car now is ngk bpr7es spark plugs. i have a set of bpr6es laying around, should i use those? also, what size should the gap be?

about the timing, u mean adjust the CAS a few degrees? how much should i adjust it?


Yeah, set CAS timing with a light to 10 degrees. Those #7 plugs are colder than the #6 plugs keep the #7 plugs in. I like a bit tighter gap, around 29-30.

There's a lot of great cheap mods you can do.

When I was first modding I replaced all the small diameter rubber intercooler hose with larger ID radiator hose.

The turbo outlet elbow is also very restrictive as well as the throttle body inlet elbow, I made high flow ones, you can buy bigger elbows from several vendors.

Remove the fog light, that blocks air flow to the I/C.

Cut open part of the plastic fenderwell behind the I/C so more air can flow through it, the louvers don't do a good enough job.


All this was reasonably cheap to do and netted huge gains at the track.

Another good mod that cost a bit but still is reasonably cheap is to replace/weld on 2.5" mandrel bent intercooler in and out pipes onto the stock I/C, the stock I/C pipes are very restrictive.

Weight. Get rid of excess junk, the spare tire, subwoofers, heavy tool boxes.

You might want to consider a few cheap tricks to keep things a bit cooler to prevent knock.

Run 1 step cooler plugs. (Make sure your wires are good too.)
Block off the Throttle body coolant lines.
Block off the EGR with a block off plate.
Flush and fill your cooling system real good, put in a 1 step cooler thermostat, use a 50/50 mix of antifreeze/water and add some Water Wetter brand cooling system enhancer to it.

A good freebie is to bump the initial timing setting. folks say this does nothing but I've track proven it to add 8-10 HP. Sure the ECU sets timing, but it uses the initial setting for reference, bumping the initial timing a bit insures full timing, these motors like a lot of timing anyhow.

A properly running 1g with all the freebies, minimal mods, stock exhaust running 18 psi boost can easily run 13.5@100 in the 1/4 mile, a huge improvement over the 14.8-15.1 stock times.


are these some things you can do on 2g's too? i haven't really heard of doing some of those things to 2g's [TB coolants and EGR]

i think i have an oil leak now...i know i had a SUPER-SMALL oil leak before, but it wasnt bad enough to leave any spots in my driveway, maybe just 1 or 2 drips. Ive noticed it since i upped the boost. I left my car parked for the night, backed out of my driveway to go somewhere the next morning/afternoon, and noticed maybe a 6 inch(concrete driveway, so it spread out a lot) oil stain. Ive also noticed small spots in other places where ive parked, but sometimes no spots at all. I was thinking maybe it was the oil pressure switch, cuz it had oil crud on it, but I'm not sure...Anybody ever have a problem of upping their boost and noticing oil leaks afterwards?



1g eclipse gs-t, in case anyone forgot :rolleyes:

The only extra oil leak I get at high boost is when the dipstick blows out and douches the whole engine bay...

duck tape it :biggrin:

check to make sure the valve cover vent line is connected to the intake or filter or whatever. i notice mine pops off once in a while. not that this would be a big source of oil, but it is a place to check.


but back to the Q i had before, anyone [2g turbo] blocking their throttle body coolant lines and EGR plates?

Blocking the TB coolant lines does nothing for performance (just trust me on that ;) ) but I did so I have fewer water lines to bust open and screw me over. It will douche your idle, so you have to be prepared to deal with that. You can toss teh EGR with no side effects except for the CEL it will give you. If you replace the vac line to the MDP sensor with a 6 foot long line, the pressure drop should trick the ECU into thinking its working. Doubt it helps much with power though, I dont think it operates at WOT.

I know this is a realllllyy old post, but i was just going through the forums and saw this.

TalontedEcLiPsE! that was my first name when i started really modding my car. It's amazing its still on here lol. I read the entire thread, and I asked so many questions that now seem really stupid lol. A couple years from now though I might look back and see the questions I ask nowadays, and I'll be like "what a newbie question".

No real point to this reply, just thought I'd stroll down memory lane