rx7legend

hi, i want to know if anybody here have installed there external wastegate on the hotside of the turbo instead of the manifold. i want to hear opinions on this.

thanks

kungfuroy

iTrader: (6)

that defeats the purpose of the wastegate, to have the exhuast bypass the turbo

hurleysurf24

iTrader: (3)

lol ... ditto
what purpose would that serve ?

Aaron Cake

iTrader: (1)

Yes, it's been done before. Some searching will turn it up in the single turbo forum. If the wastegate is mounted directly to the turbine housing you can get it at an ideal angle off of the runners for optimum flow. The result in theory is better boost control.

rx7legend

well that's what i have and it seems there's something wrong, yesterday on the dyno i was creeping to 18psi. the spring that the wastegate have is 9psi, i tried to figure out wth what's the problem but couldn't find anything.

rx7legend

i know this been done before, especially on dsm's, just curious if any rotary owner have done it. do a search and see the results, it's not something that won't work.

Aaron Cake

iTrader: (1)

Too small a turbine housing, too small a wastegate, etc.

brando54009

i wouldn't do it. my buddy did it on his and for one it was just a waste of a turbo afterwards and for 2 at higher rpm's it would start creeping. its just not all that great.

your boos control problem could be from not having it mounted correctly. the exhaust gases are bypassing right by the wg.

rx7legend

well the turbine housing is the stock S5 and the wastegate is a turbonetics evolution 35mm. the boost was creeping all the way to 18psi and i didn't even heard the wastegate opening. any other thoughts??

arghx

iTrader: (3)

remove your boost controller and run a direct pressure source to the wastegate. it should open at spring pressure unless you have some other problem.

rx7legend

yes i thought of that but how will i up the boost withouth the boost controller. ill do what your saying first. maybe my bc isn't working right.

thanks man

BLUE TII

iTrader: (9)

I also have an external wastegate on S5 stock hybrid w/ 60-1 HiFi compressor and 15 deg clipped "P" trim exhaust wheel.

Started out w/ ported wastegate, "O" trim exhaust wheel and boost creep to 20+ psi at 3,000rpm.

Went to "P" trim exhaust wheel, really ported stock WG open air vented out the back of turbo, boost creep starting at ~5,000rpm then.

Next clipped the "P" trim exhaust wheel 15 deg, put on the 60mm HKS GT external wastegate and max ported/shapped the WG passages, boost creep still on the top end.

Then ported out the stock turbo manifold velocity stacks and the turbo housing up to the WG ports.

Finally fixed boost creep but lost some low rpm boost response. Max boost (15psi) at same rpm (3,400) as before and better top end power.









Oh, and the wastegate extension tube dividers kept failing- don't bother trying that.

First 1/8" thick SS one failed by cracking in half right where it enters the curved tube after ~3,000 street miles, but I figured the expansion broke the welds and then it blocked the tube and was broken.

Second 3/16" SS one was mounted with a floating carrier ring at the WG side to slide with thermal expansion. It lasted over ~20,000 miles of street and race before it ripped in half in the same spot. No broken welds this time.

It only loses a tiny bit of boost in the 1,000-2,000rpm range though without being fully pulse divided. Still gets a couple psi boost by 2,000rpm.

-edit- Oh, and don't keep the EGT probes in the manifold for normal use if you put the fittings there like I did- just for tuning. They lasted ~20,000 miles as well before melting off and denting a rotor pinching a corner seal requiring an engine rebuild.

The temps were never in the Greddy meters red zone - 800-1,000C during lean cruise, 700-800C under load.

-edit edit- And don't bother w/ the copper gasket. That ~3/32" one failed after ~25,000 miles and now I am using a stock layered SS one ported out to fit.

arghx

iTrader: (3)

yes this is for diagnostic purposes only.

rx7legend

lol, good to see im not the only one out there with these setup, but im really sure that you ported the crap of the stock wastegate passages of the tII housing, i think im going to do the same since i have to take the turbo out again. my wg passages are ported but not that much. ill try the manifold passages and also the turbo housing up to the wg ports. thanks for the heads up on the egt probe, but i installed mine on the downpipe.

thanks

rx7legend

another question bro, have you tunned your car yet with these setup????? if so what hp did you make it out. i was pushing 260whp at 16psi on 5000rpms when my turbo loose the bolt that hold the front turbo wheel. i had to go because the shaft got damaged. if everything wouldve gone good it was going to make 300+whp easily but oh well.

Aaron Cake

iTrader: (1)

Turbine side is too small.

If the wastegate isn't opening though, you have another problem.

Rotary?Cool

Sounds like the bullet that killed JFK? I could understand turbine damage.

Aaron Cake

iTrader: (1)

Something flies off the probe, hits the turbine, then in bounced back into the engine through an exhaust port.

BLUE TII

iTrader: (9)

No, it was definitely the rear EGT probe melted off and was pushed to the front rotor through the wastegate extension tube where it became imbedded into the rotor right above a corner seal thus sticking the corner seal in the hole.

There was no other damage to the engine and the stainless capillary tube was still stuck in the rotor.

The front EGT probe was not melted off, but was bowed from the heat.


The car has yet to make it to the dyno. When it was on 225/50-16 max performance street tires (200 treadwear) it would spin the tires in 1st-4th gear. It now has 245/45-16 Toyo RA1 (100 treadwear DOT R) and it mostly hooks up in 2nd in a straight line, 1st gear is wheelsping at 1/2 throttle have to shift to 2nd at 5,000rpm it gets so bad. 13psi boost.

I would guess it is making over 300RWHP.