Hey all. I'm kinda excited today. Hopefully I didn't make a mistake, but who knows.

I've been looking at turbos for my 3.4 for a while now. Ebay chinese t3/t4 50 trim/.63 ar models look good, but there is way too much bad karma out there to buy a $200 turbo and slap it on and call it good. Plus, they don't have water cooled center sections, and I'm bad at changing oil, so coking would be a concern.

The good t3/t4s from turbonetics/garrett cost $1000, which is what I have planned for the whole deal.

So, I researched MHI (Mitsubishi) turbos and decided that a TD05HR-16G6-9T would fit well. The map is very much the same as the 50trim T4, and the 9CM2 turbine is like a A/R of .65, a touch bigger than most .63t3 people are using...cost??? 365CDN delivered. Hopefully it's as advertised!

Chay

You're an english teacher too. Ok, sorry for the vague pronoun.

The thing was the fpr, but I meant from a systems point of view...how does it integrate. I understand it boosts fuel pressure for manifold pressure increases, no big surpise there, it delivers more fuel.

I get what you mean by the afr and rpm. What I mean is that to fully deterine flow you need map, rpm and iat. With only a map signal, the fpr could be fueling too much or not enough, so it's kinda like a fudger, or good enough. Am I getting that right?

I guess given that the AFR can be between 12.5-13.5 on boost it's not a huge deal. What was the cost, do you remember??

Thanks,

C

Understood. I will move my iat to the area preceeding the throttle body somewhere. It's advised to use a open type for the turbo too, because they respond better (Quicker) to rapidly changing intake temps.

I looked at the density change from 0 to 200 deg F. It's not really that much, like 23% for that massive range, so I can see why it's not used sometimes ((0+460)/200+460)). I was kinda blown away how little it changed actually. I bet the 02 sensor can make up for it in most cases, then at wot it's not used anyway. when it's cold it's hard to detonate, so the lean mix doesn't really hurt you. It all makes some kind of sense.

I'll check into it. I'm still kind of curious to see if I'm up to the challenge of tuning it. I'm looking to trying the process after reading so much material.

Chay

One more thing...looks like I got boned on the turbo.

I saw some compressor maps which looked good, rated in CFM and I bought it....but they are crap. I should have known. When I got the real maps, rated in KG/second, the turbo compressor is a bit small. The turbine should be ok. Crap. I'm going to try it anyway, but I don't expect much in the higher rpm ranges(4500 and up). Oh well, it's a street car and I don't like going that fast anyway, maybe it will suit me. I'm just going to have to watch the iat's when I first go at it.

Chay

CFoss wrote: Understood. I will move my iat to the area preceeding the throttle body somewhere.

I simply drilled another hole in the end if the plenum, right beside the power brake hose.  My (88) manifold had an extra boss/drill pad right there!  Tapped out to (3/8?) NPT, installed sensor, lengthened wires, done.

Not a half bad idea. It would get it away from a congested area too.

I like.

C

Dr.Fiero wrote: I added (moved really) my IAT probe over to the far side of my upper intake plenum.  Figured there's no point in measuring the air temp over at the filter!

A related question... At what air temperature reading from the IAT (MAT sensor) does the ECM no longer richen the mixture for "cold" weather driving?

And can that be artificially induced by grounding or shorting the IAT?

You can probably see where I'm going with this. After the engine has been running for a few minutes, I'd like to fool the ECM into thinking it's a hot day and the engine is all warmed up to see if gas mileage can be improved.

[EDIT] After posting I came across http://www.gmtips.com/3rd-degree/dox/tips/mat/mat.htm - this interesting article  about relocating the MAT sensor. That article is one of many informative tips to be found http://gmtips.com/3rd-degree/dox/tips/tips.htm - Here .

I'm not sure abot the ecm programming, but the iat can read temps down to -40.

I suspect that the closed loop ecm feedback will override your change in the iat signal. The ecm makes a best guess on the airflow with the rpm, map, and iat. Then it injects and checks the o2. Then it modifies the signal via a fast and slow feedback system (BLM, INT values). So I doubt you'll make a dent.

Unless, of course, you run open loop, but that's another story.

Opinions?

Chay

"Will the turbo simulator require cleaning or maintenance?
Yes, but not really!"

Now that's some funny !hit.

C

I don't care what kind of ram air you are never going to get over 1psi boost in your intake plenum without a mechanical device to raise the boost. 

      At best my holly scoop takes me from a negative pressure in the plenum to near zero when I am at a 130mph cruise.   

      If you by some crazy way, all you would need to cheat the system is a rising rate fuel pressure reg, and a check valve so the 1 bar map did not see boost.  With the minor amount of extra air the car would be fine.  The rising rate fpr would actually not even be needed until you found a way to make more than 2lbs of boost which is a LOT for a ram air system, if achievable at all.  

      Now if you manage to find a way to do it, please document it and sell the documents.  As everyone on the Fiero planet will be doing that mod.

Extra 200hp on what? A 20L engine?

Assume 1.5cfm/hp, extra flow would be 300cfm.

That's a lot more flow.

10% power I can see, at some astronomical speed, unachievable on our streets, thus rendered useless.

As far as your fueling question, it would not correct on speed. As the capt says it would be ok. It might be a bit lean at ultra high speed and WOT, but that's it.

It's been said the ecm can trim out 6-8% variance due to learning, so part throttle would be ok.

Chay

I got my turbo on the weekend btw. It is in very good condition, end play is minimal, wheels look good. I'm disassembling it to clean it and check it out and midify it so it can be clocked.

So far so good. I think I'm going to get the 20G upgrade to improve the turbo compressor characteristic and order an external wastegate for lower boost setting (Stock is 14lb or so), plus a large size wastegate will help with backpressure issues if the turbine is a bit on the small side.

So, for $500 I'll have a water cooled correctly sized street turbo. Not bad.

Next, I'm looking at at least 24lb injectors, which will be ok to about 200 hp at .60bsfc, 85% duty cycle, 45psi (fairly conservative).

They're going to be more than the 19lbers, but I need them if I start making more power. Better to do it right once I think.

Chay

By it, you mean the wastegate?

Yes, I have thought about it, but I don't know if I need to.

My plan is to try a 3" exhaust without a muffler and see how loud it is. It should not have significant back pressure with this type of system, so plumbing the wastegate back into the exhaust won't be a big deal performance wise.

If it does get too loud I'll have to muffle it and see how performance is affected. I don't really like LOUD cars.

I just bid on a set of 2002 LT1 28# injectors, wish me good luck!

Chay

I've also been toying with the idea of building a proper boost controller with pid feedback from a second MAP sensor and some type of actuator on the internal/external wastegate. I'm not sure the internal will be able to handle the flow and there might be boost creep...all to be sorted out in the wash.

For the controller I need a pwm controlled actuator...any ideas out there? The egrs and cruise modules I've seen use vaccuum for the mechanical force so they wouldn't work with boost. Any ideas on something that would work?

Chay

I get that I need a wastegate...No worries...I was vague on the language there.

There are lots of choices. I suspect the best gains on 'divorced' wastegate exits are on marginal original exhaust systems.

It's a balance of plumbing complexity vs performance gain. I think the main obstacle to flow in my system will be peak turbine flow, therfore a large wastegate makes a lot of sense. With a 3" system with very little flow restriction I don't think a seperate exhaust will be merritted.

Chay

The Supra was running a 3" . But yes, I suppose for the smaller turbo (I presume) it might be an acceptable trade so you don't have to deal with the extreme noise.

It the first car I've ever turbo'd so I'm open to all this stuff. I think it's a good discussion.

The supra was also probably running a CAT and a muffler, which can be high restriction devices, so I can understand the seperate path.

What turbo was the Supra running? At what boost level? I'm boosting to such pathetic levels in comparasin to most turbo guys that backpressure is pretty weak.

If a guy is running a t4E-50 at 20psi, and 6500rpm, yeah that a lot of flow. We can use the same compressor, but run 5,6,8 psi without a lot of work on the 60V6, not really a lot of flow, especially with out weak top ends.

Anyway, it's trial and error at this point. The turbine side is less quantitative, so it's hard to get a feel for performance changes, and then there is the street vs 1/4 mile vs top speed tradeoffs to consider (IE: My engine won't spend a lot of time at 6000rpm WOT).

Chay

CFoss wrote: My plan is to try a 3" exhaust without a muffler and see how loud it is. I don't really like LOUD cars.

Something about these two comments in the same post just doesn't jive.

It could be LOUD, then I'll take steps to fix it. It probably will be too loud, but I have to try it. I think the turbo will suck up a bunch of sound energy.

Also, I found a lead on the boost controller...you can get a typhoon cyclone solenoid for pretty cheap. I'm going to try it hooked up to my own controller.  It should work up to the limitations of the wastegate. Basically, I'll match the characteristic of the 40mm wastegate electronically so they won't fight each other, plus I'll slow it down so it doesn't oscillate.

Also, I think I'll run a 40mm external wastegate and synchronize the internal wastegste control (Via pressure). From what I've read the internal won't limit boost until like 10psi. The internal wategate is sized thinking the standard application boost is higher than this. Because I want to boost lower, I need additional wastegatage (Ok, I just made up that word).

The internal wastegate is twin 20mm diameter holes, which when their area is added to the 40mm wastegate, will act a little smaller than a 50mm wastegate. It's a place to start.

Chay

I hope you are right. From my calcs the compressor will be a bit small but I think the turbine should be right on the money.

I didn't want to leave the spool too long, cause the intake system runs out of flow up top anyway. My idea was the car will be quicker if I maximize the low end potential rather than try to extend the high end torque. It will still extend the useable rpm range, but not to the extent that a big top end turbo would. Plus I like to get sucked back into the seat, but ease off at 120k...hopefully with the Honda in the rearview. I'm just not a 200kph guy anyway so the very top end is less a concern.

I'm starting to think I'm going to try the 16G6 compressor and log the intake air temps as I start boosting above 4 psi. If the intake air gets too hot too quick I'll know I need the bigger compressor for increased efficiency. If not, I saved $250.

I'll just run it rich until I find out.

Chay

 Chay I am no expert when it comes to Turbo motors, however the 3.4 in your Fiero has more than enough punch off idle, if you can light up the tires now in first gear, then I would try to tweak that turbo to spool much later, like in the 2500rpm-3500rpm range.  Once you clear 1st gear all your shifts will take place at a much higher rpm and the rpm drop will only go down to 3000rpms at the lowest.   

Congrats on getting it this far, I am sure no matter what happens you are going to have a blast with it.

You're right about the spool range. I expect it to spool right around 2500. Any lower could be a waste.

It may make boost threshold earlier, but I don't expect it to max boost until maybe 3000. This is all specuation, and has primarily to do with the turbine sizing, which is supposed to be similar to a .7ish a/r (Most run a .63T3, so I'm optimistic).

Ideally, I'd like full boost level by 3k, to take the useable rpm range from about 2.5k to about 6k. Max hp will still be around 5200-5500, but will be higher than stock of course.

I did win the 24/28# injectors from a LT1 (There are either 24# or 28# depending on your fuel pressure setting). I should have plenty of fuel.

And I got a 1227730 and harness, plus a 60mm wastegate cause I think I'll be bypassing quite a bit at initial low boost settings and I don't wan't creep, now to get a bov and figure out the $58 programming (Syclone/Typhoon)....should take me at least another 2 days eh?

Chay

As a note to your original question, as long as you have good traction, the later you leave the boost the slower the car will be in the quarter. If you boost later you may have a higher final speed, but it will be slower overall.

Given that I'll be on the street/autocross, I'm looking for more low end.

The Fiero manifold flows ok at between 2.5k and 5.5k, then it dies...this is common knowledge. So, if you bring the boost on late, it will feel like you are extending the torque way up into the high rpms, but you will miss the oportunity to build higer torque earlier.

From Displacement = VT+1/2AT^2, the faster you get going earlier, the further you go. Or, the other way to look at it is getting going faster earlier raises your average speed more than having a high top end speed for a shorter period of time (And therefore reduces your time for a given distance).

This is critical on a short duration course like a 1/8 or 1/4 mile (Or god forbid the street).

It's pretty wordy, hope that makes sense.

I just have to get the power down once I start making it, but that's the fun part. The car already goes fast enough for me. It doensn't get going nearly fast enough though. (From that video...Rotary? I want STUMP PULLING torque).

So, I've thought about it a bit.

Chay

Hey Chay, looks like you're having some fun there!

I'm just curious, what was your reason for cutting the runners as oppossed to mounting the tubes on the ends of the original runners? I'm not suggesting you should or shouldn't have, I'm just wondering why you chose the path you did?

Here's a couple of images of a dual-plenum manifold I almost bought from the Mall at Pennock's over a year ago. I eventually decided against it for three reasons...

1) More trouble than I needed.

2) Made of steel and heavy.

3) Ugly as sin.

Chay, I don't remember the name given to this technique/addition, but had you looked into adding "extensions" to the runner tubes where they enter the plenum? They stick up a bit from the floor of the plenum. It's supposed to help flow. Do you know what I'm talking about?

Okay, don't laugh... I tried to draw it for you. The runner with the extension thingy is on the right. The shape isn't right, but it should be good enough to get the idea across.

Dr.Fiero wrote: So....  Short is good.

Keep in mind I was only wondering why Chay cut the last inch or so off the runners.

CFoss wrote: ...enlarge the holes in the pipes to accept a bit of the runners into them. Then I don't have to be so carefull to match the ports too, and weld the outside of the connection.

Hey, now you're talking. Sounds great! 

Keep in mind they need to be trumpet shaped.

Yes, "velocity stacks". That's the term I couldn't remember.

CFoss wrote: Good tip.

Thanks Chay, I hope it yields you a few extra ponies.

Someday you'll have to make it across the pond to a club function so we can all meet you and your Fiero.

CFoss wrote: Will it work? Who knows.

If it doesn't work, you've only lost a bit of time.

If it does work, I want at least half the credit.

Flow-bench numbers for Stock intake and SR14 & LR17 below.

CFoss wrote: I think what I might do is redo the plenum. This time I'll cut the holes to accept the runners in the flat plate, then insert the runners and weld tabs on the runners to create a horn style velocity stack (Think like a tweeter horn in reverse). Then weld the runners to the flat plate, and finally the flat plate to the tubular material. It would be more effective that way i think.

I think that's a great idea.  I was disappointed when you posted the image below because I felt you had severely limited yourself with what you could do with the plenum. Doing it over again in the manner mentioned above will give you ample opportunity to do a much better job.

Will you be fabricating a balance tube between the two plenums?

CFoss wrote:

CFoss wrote: The shape of the plenum will be the same, it's just that it will be assembled in a way where I can work the interior.

Oh, I knew what you meant, and I agree that's by far the best/only way to do it. 

CFoss wrote: Found what I'm looking for: http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=200384376524&ru=http%3A%2F%2Fmotors.shop.ebay.com%3A80%2F__%3F_from%3DR40%26_trksid%3Dm39%26_nkw%3D200384376524%26_fvi%3D1&_rdc=1 - HERE

Holy sheeeeit.... $39(US) each!  

Do you really think it's worth about $288 (six velocity stacks, shipping, dollar conversion) to buy those particular pre-made velocity stacks rather than to fabricate something yourself (or to find a less expensive alternative)?

CFoss wrote: I found out when I put the new middle manifold on the lower one that the reason the runners come up is the valve covers get in the way. So, I need to redo the plenums for sure!

Oops!

Just run her without valve covers.

How long are you going to make each plenum (is it 13"?), and where (relative to the original TB location) will the two throttle bodies end up?

Looking more and more like the starship Enterprise.

LOL

Oh this devolved so rapidly...

CFoss wrote: The cheque is in the mail btw.

Got it today, thanks. Let me know when the package arrives. Should be there by now.

wayneh70 wrote: It's not cheese it was in the movie!!!! Scotty: "The Enterprise? I’d like to get my hands on her ample nacelles, if you’ll pardon the engineering parlance."

Wayne, the first step to recovery is to admit you have a problem.

Don't get me wrong Dave, I really like all the various incarnations of Star Trek. I still fondly remember watching the original series on TV back in the mid 60's. However, I'm not such a devoted Trekkie that I can recite obscure lines from a movie.

No updates?

Looking good.

Did you end up with anything resembling velocity stacks inside the plenums?

CFoss wrote: They look pretty flowy to me.

Is that mechanical engineering lingo?  

This looks great, Chay. I'm really hoping you can make it to Vancouver some weekend for a club meeting when you've got this all together!

I'd like to come to a meeting. I think it would be fun to give a big presentation on turbo calcs and stuff if people wanted, but I'm not sure when I can get over. Busy busy.

I've sort of decided I may as well do the remote ignition module while I'm at it so it will be a while before it's on the road.

I just hope after all my dicking around it will still run!

Chay