both waste gate ports? so like... the internal ones are running full open all the time and the external is keeping the cap on until you need to bleed it off? hmmm.... are you disabling them or have you removed them or is it even possible to remove them?

 

It sounds like you need to weld up the two passages to the stock flapper valves and run the wastegate off the manifold.

 

Couldnt it be any 05 housing? Or are you talking JDM MR? All the same no?

 

I'm confused Dave. All '05s have the 10.5cm2. I thought that is what was on the car already?

 

I believe he has the 6.5 titanium turbo true it does have a 10.5 hotside but I think it is different design than the 05 hotside which is also is a 10.5?

 

I vote for welding the internal wastegate flapper shut, we just did something similar to this with a Sti and damn, it rocks.

 

Dave .. couldnt sleep last nite and my mind was running 100mph thinking about things . Why do you need a waste gate at all ? If the turbo is "maxed out" f**k it weld the stock wastegate closed and DO NOT run any kind of waste gate at all , why would you need a waste gate anyways??????

 

Without any wastegate, there would be no ability to regulate the boost levels at part throttle and low load.. At least thats the best I can gather..

ALL of the 05 turbine housings use a new flapper design (its one merged port with two outlets) but all of the USDM 05 housings are 10.5cm2

I'm also curious if anyone besides myself has looked at the 05 compressor cover closely to verify there is any more than trivial differences (that I measured in a rather nonscientific method).

I'm not so sure that replacing the wastegate is a good solution (it adds a pretty significant expense too) Perhaps switching to a forge adjustable wastegate actuator and a heavier spring can help prevent the flappers from opening under higher boost.

Remember, a weak wastegate spring will cause boost to taper, if it was due to insufficient flow you would get boost creep as the ability to flow the gases through the ports becomes a restriction. Although putting in a stronger "External" wastegate offers a few advantages, I don't really think its a true solution because the components can prove to be pretty expensive. IMHO you can get the same results with an adustable actuator. The advantage of the external wastegate is the ability to bypass flow FASTER which allows better control of the boost when needed, but this doesnt appear to apply in this situation.

 

I completely removed the internall gates on this 6.5 TME turbo,which is a 10.5 housing. I went back and compared a dyno sheet I had printed off from before this morning to the one I made yesterday. This stock turbo is unbelievable, the power it is making. The two open ports really seemed to kill the turbo though,that is all I can figure and believe me, I was up last night thinking about it.

The MR turbo is completely different than the 6.5 TME 10.5 turbine housing. The TME uses two wastegate ports just like the standard EVO turbo does. The MR uses a single round puck to cover one port that has two small half moon shaped ports in it. The MR's hold rediculously steady boost levels.

I am going to just buy a new MR turbo, expensive test but that looks to be the HOT ticket if it works.

To give you an idea how crazy this is the low end of the car because of the spool up has lost 100+ horsepower in areas. Top end is increased though with the boost holding 19 now instead of 17 psi.

MPH hp internal gate hp external gate
70 380 392

75 365 388

80 360 377

Some points in the low end

MPH
45 240 148

50 305 199

55 350 265

This is some of the things you aren't getting from many other EVO owners/tuners guys. Bragging rights aren't what I am here trying to accomplish. It's easy to come here and tell you guys how great this external gate is working and just show the top end. Hell many of you would line up to buy this new part. Problem is the internally gated turbo is going to kick the crap out of the externally gated turbo.

I really don't want to run the external off the manifold in the EVO. Probably work well and I may end up trying it if the MR turbo doesn't fix all the problems.

I think the next step is definetely using the MR and seeing what happens. Time is getting shorter by the day here, I need the car to be finished, for the most part by the April 15th race.

Oh, the reason you can't just weld the wastegates closed it the turbo would then make 30+ pounds of boost down low and then fall off, not feasible for running 94 octane.

David Buschur
www.buschurracing.com

 

For some reason I thought that the max psi your set up would run was 21-22psi then fall to 19-20 b/c of the clipped wheel , cfm's runing out , ect.... , h*ll try a stronger waste gate spring to keep the flapper closed at higher Rpm's ? So the psi to open the wastegate would go from 12 psi(stock) to 20 psi(stiffer spring) when you get this all figured out you will have a whop-as$ turbo on your hands !!

 

hey malibujack... do you know if adding a stronger actuator spring will cure the problem AND not introduce boost creep? because i don't wanna swap one evil for a worse one. i've been tryinna get people to cough up ways of fixing boost taper for quite some time now.

no wastegate is no boost controller and that's quick ticket to a hop skip and a pop your engine.

i asked about removing the internal gates because i just don't understand how the cavity of the msising gates is causing things to spool up slower, the only explanation for a slower boost up is that gas is getting wasted off somewhere somehow right? if the external gate is covering everything up unless it's open somewhere somehow then it should keep a cap on things. i just don't get it but i'm sure dave is doin' what he can with it, if he says scrap it... then it's scrapped.

i actually never did think of the more expensive option of sealing the stock waste gate ports with the gates removed and then running an external gate off the mani or even off the hotside of the turbo! for those of us that want minimum spool up time, torque and minimum response time (i read somewhere of a mitsu rallycar using the 9.8 hotside to keep fast boost up and boost response) this is a much smaller cost than replacing a turbo with a buncha fancy jazz that is just the same stuff but prettier and will definitely be counterproductive if it's bigger. is it pretty much a known fact that you can make more torque more quickly with a 9.8 than a 10.5?

also the stock turbo is nowhere near maxed out on pump gas... you could try running a turbo gatefree but you'd have to do it on a small one that doesn't make hardly any boost at all... some diesal applications are like this but this turbo is not only too big but like dave said.... it's capable of an excessive amount of boost early on.

ok... quick final question and potato toss since we're kickin' the can around the circle. fp makes a turbo that is gated right off the hotside. how do they do this? do they just punch a hole and slap on a flange for a wastegate? if so... is that the same as using the internal gate cavity and slappin' a gate on top of it... if not can you just punch a hole through the internal gate cavities and flange up for the wastegate or do you have to seal off that area (maybe inside and out even) and then punch a hole on a different part of the hotside and then flange and put the gate on.

waiting for answers in eager anticipation.

 

Actually if you look at the TME compressor map, it does seem to be possible to max it out on pump gas (esp. 94 octane). I'm guessing that Dave's RS is hitting a VE of 95% or more in some spots, which means it may flow more than 600cfm near redline, which is definitely out of the TME's efficiency range.

On the subject of adding a stronger actuator spring to the wastegate ... how about a progressive spring (or maybe two stage spring)? That would let it open up a little bit at least at partial throttle, but it would take a lot more force to open it 100% at WOT.

l8r)

 

Hey Dave,

If having the internal passages open is killing spool up from some kind of turbulance or something, why not leave the internal gate intact and run a line directly from the boost source to the internal wastegate for good low end spool up, AND have your new O2 housing with external gate bolted on over the stock gate for actual boost control? If you can't do it with your tubular setup, you could take a stock O2 housing and weld the external gate to the wastgate passage of the O2 housing and weld shut the internal passage.... you KNOW that this would work.

Keith

 

Boost creep I'm not sure with a heavier wastegate spring.. Mitsubishi's choice of spring might have been for that reason, but increasing the wastegate pressure form the 10.5psi (12psi on some cars) to 15-17psi shouldn't really make a huge difference, but add just enough additional seat pressure to possibly keep it closed. I'm speculating here, I have the adjustable wastegate out of necessity (it was cheaper than finding a new stock one at the time)

 

We have experimented with more tension on the stock spring, it is actually easy to do, just shorten the adjustable rod. The car ends up with higher boost spikes and still falls off on the top end. We have also added a larger external spring to hold it and it is the same story.

The problem I am guessing is happening right now is the two large holes are completely open. The exhaust flow is highly disrupted by this happening and I feel that is what is hurting the spool up.

I will have a 10.5 MR housing here Monday for testing.

The large cavity that you end up with on the EVO turbine housing definetely isn't helping any of the flow characteristics either.

BRB, gotta check something.......

I went to see if the wastegate will actually fit into the cavity on the EVO turbine housing. I think it could be made to fit, but the dual port on the normal EVO turbo won't work like that. Maybe the hot ticket is slide the external wastegate into the single port on the MR turbo and run it like that.........so many ideas so little time.

David Buschur
www.buschurracing.com