Wastegates: internal vs external

[technician163]

I'm new to the turbo world and just recently picked up a 1991 turbo talon awd 5 speed for $250. I am a skilled and experianced mechanic in the south central region of PA. We don't see many, if any turbo cars, so this is releatively new to me. My question is: is there much of a difference between the internal and the external mounted wastegates??

 

[meliketoball]

Pshhh, I'd check if theres a body in there.

 

[Black99gst]

wow!!, being a newbie, I am very impressed with the posts on this topic and I would like to thank everyone for their input. My main reason for the tublar manifold was curriosity, but aside from some very minor dents, this car has only one flaw-- the previous owner was a drug addict and knew nothing about cars. He cut about 2 feet of the exhaust off of the car to remove the cat and turn it in for drug money. That being so, I would like to replace the exhaust from the turbo back with 2.5" exhaust. I'm wondering if the bigger exhaust is going to cause me any problems with "boost creep". Thank you for the tip on the stage 1 upgrade list, I am going to follow that as a guide. Also, how important is the 190 lph fuel pump?? My plans are not to exceed the stage 1 upgrade other than adding some hard intercooler tubing and a fmic(they just look cool as heck) and possibly a BOV?? any suggestions on brands of BOVs?? Thanks to everyone again!!

you will be fine running a 2.5" exhaust on the OEM wastegate setup (no boost creep problems here)

the fuel pump questions: the 190lph fuel pump is not important at all, however!!!!!! having enough fuel flow through your system at higher airflow rates (I.E. more boost) is VERY important! running to lean (not enough fuel) can cause your pistions to fail... (more likely rods in the 2g, but your running a 1g... so pistons)

for your goals, i would say your ok on the fuel, i would however re-wire the pump with some nice gauge wire, then get a smaller FMIC (you dont want to outflow the stock 14b turbo with some huge intercooler) the hard pipes are a good idea, and the BOV is all about what you like to hear... just make sure it can be re-circulated back into the intake (to avoid bogging down between shifts)

hope that helps...

 

[90talontsi90]

the previous owner was a drug addict and knew nothing about cars. He cut about 2 feet of the exhaust off of the car to remove the cat

One Quick question, did he put pipe in to replace the cat? If not then I assume your running open downpipe, which is a horrible thing when it come to stock boost control. Meaning if hes did that a while ago and you've been running around with boost spikes to god knows how high... there could be a problem.

My first recomendation would be to do basic maintanence which will require you to fix all of the previous owners F#@K ups. Then do a comprission test and go from there because if that's good then boost away.

P.S. Even if your planing on just using the stock turbo you'll still end up with more airflow then your pump can produce. A 190lph is cheap and good insurence, besides the 14B becomes real fun at about 20PSI which is very much out of the stock pumps range.

 

[50trimmed1g]

Watch out with internal setups. I just blew my #1 cylinder because of a faulty actuator.

 

[gsxAWDdsm692]

With the stock boost in place, you can run a 3" no problem. Fuel isn't a major factor unless you start raising the boost. You don't really need a front mount intercooler unless you start raising the boost on your 14b. Hard intercooler pipes for the stock intercooler is a great mod. Also getting a bov can help even though the 1st gen bov's do justice.

 

[1992awdlaser]

Get a 190 pump or evo pump. ^ A 3" turboback WILL create boost creep on the internal wastegate of a 14b. So you are kind of contradicting yourself since you said he won't need a pump unless he is running more boost. When I had the 14b I put on a Buschur o2 dump and my Buschur 3" turbo back. Before I put it on my boost was at 15psi. After I put it on I took it for a ride and floored it and the boost went to 24 psi. I took the boost controller off and my boost still wouldn't below 20 psi even with the o2 dump. Because of this I couldn't go over about 70% throttle or else it would creep that high. The car felt as fast as stock with the exhaust and 70% throttle. I hated that I had to do that in order to control boost. So don't put a 3" turboback on your car unless you port the exhaust side of the turbo and o2 housing. Or better yet port the exhaust side and put an o2 dump on it. Or even better yet put an external wastegate on it.

 

[gsxAWDdsm692]

I'm stock boost and have a 3" TBE and it runs like a champ.

 

[dalatinromeo]

Same here I ran a 3" turboback with no problems.

 

[1992awdlaser]

That is VERY hard for me to believe being that you have a t25 which should boost creep much sooner then a 14b. Do you have a cat on the car? What type of exhaust do you two have^^?

 

[gsxAWDdsm692]

That is VERY hard for me to believe being that you have a t25 which should boost creep much sooner then a 14b. Do you have a cat on the car? What type of exhaust do you two have^^?

Nahh.

 

[technician163]

Just to let everyone know, I just bought this car about 2 weeks ago, and I haven't been driving it because of the 2 feet of exhaust missing. I have started it up to listen to it and pull it in the garage. I figured that the exhaust being unrestricted and open wouldn't be good for the turbo,

 

[1992awdlaser]

It won't hurt the turbo.

 

[technician163]

what about boost spike?? I figured that would not be a good thing so I haven't run the car any more than just to pull it into the garage

 

[1992awdlaser]

You won't have to worry about it if you don't beat on the car. Or if you give it like 75-80% throttle you shouldn't have to worry about it.

 

[Mr Peepers]

That is VERY hard for me to believe being that you have a t25 which should boost creep much sooner then a 14b. Do you have a cat on the car? What type of exhaust do you two have^^?

T25's just plain don't creep. There may be cases, but they are RARE and I've never seen them. The turbine wheel is so restrictive at higher rpms that the exhaust WANTS to exit through the wastegate hole. Hell, t25's have a hard time holding 15 psi to redline because of the flapper blowing open and compressor flow. The flapper also opens much farther than any MHI actuator(14b, 16g etc) will allow.

technician163:
Get an aftermarket boost gauge. The stock one is useless and inaccurate. Then you will know if you are spiking or creeping. BTW, spike is when you have the boost set at say 15 psi, and it jumps to 17 then settles back down quickly after. Creep is when you have it set at 15 psi and it slowly climbs to 20 psi by redline. You'll likely be running 10-12 with a stock setup but you get the idea(the numbers are only relative). With a stock downpipe and especially a cat I doubt you will have any boost issues. Get a boost gauge to be sure.

As for 3" turbobacks, I've had them on both of my awd's. One of them never creeped and the other creeped to 20+ psi in higher gears, exact same turbo(literally), a ported-for-flow 14b.

My suggestion, do ALL of the maintenance first. Then, get a 2.5" or 3" turboback exhaust (makes a HUGE difference in gains compared to a n/a engine), 2g exhaust mani(ported or port it yourself, mbc, and maybe an intake pipe and hard IC piping. A logger would be a good idea for safety as well and only ~$100 on eBay, and maybe a 2g o2 housing now that I think of it. Port the 14b for boost creep just in case, and set the boost to 15 psi and you'll have a fun DD, perhaps 13 second car with decent driving.

EDIT: Rewire the fuel pump! This involves running a power wire directly from the battery to the fuel pump, and using the stock fuel pump wires to trip a relay, hot wiring the fuel pump and sending all the available voltage at the battery to the fuel pump. Typical gauge is 10-12, although I had trouble soldering 10 ga with a dinky soldering gun. I have to admit I was amazed at how much more flow is available.

 

[1992awdlaser]

I get it now with the t25. Thanks for explaining Mr Peepers. I'm going to try and get you some rep points for that one.

 

[Joe-GSX]

I'd follow Peeps advice.. Fix the problems then get the exhaust The bigger exhaust is a noticeable difference!

 

[1992awdlaser]

Here you go Mr_Peepers http://www.dsmtuners.com/forums/reputation-recommendations/267410-mr-peepers.html

 

[technician163]

thanks mr peepers, that clears a lot up. what do you think about a test pipe instead of a cat? They don't have emmissions testing where I live, and I have a PA state inspection license, so I wouldn't have to worry about passing inspection. Also, I'm not totally clear on the purpose of re-wiring the fuel pump, can you explain that a little more for me? Thanks again for all your help!!

 

[1992awdlaser]

The test pipe will give you a little more power and spool. Re-wiring the pump makes sure that it gets a constant high voltage. With stock wiring as the rpms go up the voltage at the pump goes down whcih limits how much it can flow. And the voltage is already low to start with.

 

[SethA]

Peepers is smarter and more elequent than I am so he will probably have a better reply. This helped me out though:

Eclipse Fuel Pump Tech Tips

A test pipe will perform the same or better than any cat. You should run one if:

1) you don't care about emmisions / inspections
2) you don't mind the exhaust sound being louder / different sounding
3) you don't have creep issues (a test pipe will make creep worse)

Seth

 

[technician163]

ok, I see the reason for re-wiring the pump now. any suggestions on what size wire?

 

[SethA]

I ran 10ga. I know there is a vfaq on it. Go to www.vfaq.com then DSM and fuel. There is a pile of good stuff there.

Seth

 

[1992awdlaser]

10 gauge wirig.

Here is the v-faq. http://www.vfaq.com/mods/pump-relay.html

 

[GSX4BangR]

Im trying to run a evo III 16g turbo, evo 3 o2 housing, and an evo 3 manifold....so pretty much im stuck with an internal wastegate but i think i can upgrade to a 34mm or 38mm i forgot which 1 but will that be good?