Turbo gurus, have questions.

[d962r]

so in all crazyness... what kinda of whp can one get from a 4age?
Atlantic Trim (n/a) is around 250bhp.. so with some boost and a lil less comp. (atlantic are 12:1) do you think one coud get to the 300 mark.. I know it probly woun't last all day... but WOW what a ride.......

[AceX]

I know that toytech (Chris) was shooting for something like 400hp from his. You'd have to ask him how much he actually had in the end though...

[TheAmazingDave]

Originally Posted by yoshimitsuspeed

If your going to drop thousands of dollars on building a motor from the ground up why would you consider a shitty mani?

I didn't want to drop a bunch of money into high dollar parts like a nice manifold and expensive BOVs and such since I've never built or owned a turbo engine before. I've read too many threads of peole turbocharging their Mk1s only to blow them up later. I didn't want to spend $500 and wait for months for a quality custom manifold to be built just incase I **** up and blow up, then decide to stick SC. And as far as I know there is no aftermarket manifold available anymore. HKS used to offer a turbo manifold with a T3 flange (may be wrong on the flange) but good luck finding one now. I'm willing to spend so much on the actual turbocharger since it will have a decent resale value, unless I manage to destry that too. lol

I'm aiming for around 13-15 psi for street cruising. I want to be able to turn it up, possibly around 20, for track events like amateur drag nights at Infineon Raceway. If the T3/T4 is too big what about a normal T3?

When I actually start building this thing, I'm going to take the manifold to a shop and have them move the flange to center if possible, as well as weld on a flange for external wastegate if possible.

[AceX]

If you're going to do all that, you might as well just have them make a new manifold...

Anyway, a T3 might just very well be what you are looking for, but you'll have to make sure that the trim package you get has a max boost setting of about 3-5psi higher than what you think will be the boost level you want. This is better for tuning and will not max out the turbo. The last thing you want is a blown turbo.

If I were you, right now, I would call the guy who you bought the manifold from, ask if he could exchange you for a manifold with the flange in the center. Then, find the best turbo you can for what you are looking for (a small trim T3 I would think). After that, I would look around for the best engine management system you can. After that, move onto fuel systems and ignition. Then comes the planning of pumbing and intercooling. Air to water intercoolers are VERY effective, yet they are heavy, and require a bit more skill to use (you need to have an additional coolant tank). I'm sure that I missed something, but that is that jist of it.

[CpuZapper]

I can't even count how many different T3 flanged turbos I have done flow maps for... I've been trying to pick the right one out for my next motor forever. As of right now I'm running a volvo/saab (more or less the same piece) .48/.42 T3, and 7 psi happens fast, and smooth. Granted it's not as fast as a T25, I'm still more than happy with having full boost at 2800. Keeps me off boost while cruising on the freeway. One thing to keep in mind is that big turbos tend to require less boost to make the same amount of power as small turbos (in some cases) because they don't heat the air as much. I've run my saab turbo as high as 11psi, and it felt like it had a lot more to go, while my intake temps were still fairly low after my thunderbird IC.

If my maps are right, the best solution in a T3 form factor is a 60 or Super 60 trim compressor, and a .63 turbine. Should be good for over 20psi, and still give good boost before 3200. Also, you shouldn't have too much of a problem with an off center manifold. You're only looking at running up to 14psi, so the runner length shouldn't make any noticable difference... and if you put it in the center, you may have fitment issues with your dizzy! Because the turbo mounts so high on that manifold, you're going to have a lot of heat sitting there, and I'd keep it as far from your ignition system as possible. I love my Rally2 manifold because it puts the turbo lower down in the engine bay, almost to the motor mount (Rally2 Manifold). I can still run the stock dizzy, and A/C... and keep my starter on the exhaust side.

In terms of EMS, for +7 psi I would highly reccomend megasquirt with the megasquirt & spark extra firmware as you can (after some minor minor mods to the MS) run it with the stock toyota ignition, and still have full timing control.

[TheAmazingDave]

Thanks.

[ZAPPE]

Now why the t-25 of a second gen eclipse? will the 14b not fit properly? it might take the 14b longer to spool but you have more potenal (sp?) i would like to know about the fitment issues becasue i got a 14b off my last dsm sitting in my shop.

[CpuZapper]

I think that both will work fine, though I thought the 14b had a different flange on the turbine inlet. With the amount of air our engines flow when hot, any small T25 form-factor turbo will spool really fast. There's a video floating around somewhere of Brent Picasso's car with a T25. If you watch the boost gauge, it looks like he has instaboost over 2k. A 14b should be almost the same. If you want to daily run 14psi though, the 14b and T25 may do it, but it will not be very efficient - it will just turn into a hot air blower, and when you cool the air back down it will end up being only like 12psi at the manifold (assuming you have your wastegate pressure coming from before the IC).

The good reason behind a T3/T4 is that since the compressor is so big, it doesn't have to work hard to move the same amount of air at higher pressures, but the low speed response sucks. I used the T3 86mister2 was talking about on a 22RE and it felt laggy on that motor! Once it got spooled, it rocked, and the air stayed nice and cool. We switched that motor to a custom ported T3, but I don't remember the specs on it - I'll have to look them up.

My .42/.48 on a 4AG was about perfect for anything up to about 15 psi, but it did start getting a little inefficient over 14. It had a little less response than a T25, but my intake temps stayed a lot lower, even without an intercooler. If he wants to be able to run 20psi for track days, a 14b or T25 will make the intake air so hot you'll melt your intake manifold... just before the turbo explodes That's a lot of boost for one of those. A T3 however could run 20 psi all day long as long as it's not at the end of its range (like the little Saab turbo I'm running). Also, if you're going to run that much boost, or even just 14psi, I'd reccomend running a "Wet" water-cooled center section. The high amount of backpressure caused by that high of boost will really heat stuff up, and having it cooled by something other than just oil will keep the turbo happy.

[ZAPPE]

Cpuzapper it sounds like you know your turbo's where as i can't tell you a toyota turbo from a hole in the ground so my question is where does the turbo for a 91-95 Mr2 fit in the grand scheme of turbos ie what is a low turbo and a higher turbo or what is the closes to it 14b t-25 16g? the reason i ask is i will be looking to buy one at the end of the summer if not sooner and am wondering if i should keep this 14b i have or the evo3 16g and make it fit or sell them for a larger toyota replacement t3\t4. thanks

[Luni]

Id have to see a flow chart.

I still just cant see a super 60 spooling for crap before 3200 rpm on a 1.6 liter... I still think its too big of a turbo for that engine for a daily driving basis.

[TheAmazingDave]

From what I've read in Maximum Boost, compressor wheel size doesn't effect lag at all, it's all in the turbine. As long as you size the turbine right, the compressor doesn't matter much as long as the turbine keeps the compressor side in its efficiency range.

I hope that made sense.

[Luni]

You are correct, but the thing you forgot to mention is you cant have a turbo that has a SMALL exhaust side and a BIG compressor side make big power. Theres generally a decent balance between the 2.

Look at the 60 trim CT26 upgrades. They are for the most part shit. You get like 20 more hp, your turbo hits harder, but you still fall on your face why? Because the exhaust cant keep up with the intake. So you have to make your exhaust a bit bigger. Once you start doing that to size it up to the larger intake side, you just lost response. And on a 1.6 liter engine, you dont really have a whole lot of room for loss of response.

I just want to see a dyno of a super 60 on a 4age and know what mods are supporting it, so I can see when the thing starts to spool and come alive. Ill retract all my statements about larger turbos if I can see some sort of proof. And Im not saying you cant run one, Im saying it wont be near as responsive as a better sized turbo for the application.

[TheAmazingDave]

Cool. I understand what you're saying, and it makes perfect sense.

[CpuZapper]

The Super 60 is what many of the Miata guys run on their 1.6s without any problems. I'll see if I can dig up some compressor maps or other evidence. If you really want, I can try to dig up some .63 turbine maps too. I already said it's not going to be as responsive as a T25, or 14b, or even a Saab T3. If he wants to reliably run 20psi for trackdays (and I'm assuming he doesn't mean a couple drag passes - they don't count for my arguements) where the turbo is on boost for long periods of time, something small won't take it well. Also, if he wants to daily drive at 14psi, it may be a bit laggy, but it's a decently priced turbo, which he wanted (you can get used ones off of a 1985-ish Thunderbird for cheap - they're "60 Trim" but the flow characteristics are almost the same as the Super 60, which only has a physically larger wheel and housing).

Keepingthe turbo off boost while cruising will also save on his fuel economy. With a T25, twitching the throttle can throw you into boost, whereas a bigger T3 will actually take some throttle to bring it up. Any time you're on boost, you use more fuel... if he's doing this cheaply, I doubt he wants to be getting 20mpg or less all the time.

If he wants to dish out a lot of cash, the GT28RS is probably the best balance between response, and boost capability. I only made the T3 reccomendation because new, they are about half the price of the GT28RS, a couple hundred less than a GT28R, and used they're about the price of a decent BOV. Since he said he's doing this on the cheap though, I made my reccomendation considering longevity, price of rebuilds, initial cost, and adaptability. If he decides that something isn't to his liking, all he has to do is swap wheels and/or housings on either end - something you can't do on the GT28R(S). Also, the T3 has the feature of coming with an internal wastegate, another great feature for someone not wanting to spend a lot of money. Think grassroots... If someone really wanted, they could probably build most of a turbo setup for free (if not entirely).

EDIT: I just re-read the entire thread, and saw that he was talking about drag racing... I guess I should revise some of my thinking. I personally would still stick with a .60/.63... but a .60/.48 would give faster spool, with the loss of some top end. The .42/.48 would be way too small for dragging @ 20psi, just because the compressor doesn't flow enough. If he keeps the revs high, which I assume he would drag racing, a .60/.63 should rebuild boost between shifts fast enough it won't matter. I guess I'd still reccomend the same turbo... unless he's autocrossing.

[Luni]

I see what youre talkin about CPUZapper, and I guess, in relativity to drag racing, you dont want your turbo being TOTALLY responsive, you want to be able to get going before your turbo starts to POUND you, or you will just be spinnin the tires and makign crap 60 ft times.

I was also thinking something like a T28 might be a good turbo. Maybe one of those "big T28s" would be a good one. Ive seen ones with ball bearings that are relatively SMALL turbos, but put out a LOT of HP on SR20s and 4G63s. Id imagine it would be a bit laggier on a 4A but that would be a GOOD thing because of what I was talking about earlier. I still cant see him doign 20 psi on a T3/T4 type turbo on a budget though. Hed have to fully rebuild the whole damn engine with a megasquirt or other EMS.

Since this thread is getting long, 86Mister2 you should update your brainstorm with us and lets figure out your exact goals, budget, and review the turbo info and options and opinions laid out so far and lets see if we can narrow it down to more specifics. That oughtta help us all get on the same page.

[CpuZapper]

The "big T28" would be huge for this motor. My friend's DSM is laggy as hell with that turbo, though it does rock when it hits 17psi.

I agree that doing 20psi is a little much on the stock electronics, but with bigger injectors, and retarding the base timing a couple degrees it should be ok if he's got a GZE computer. Might have to tighen the AFM down a few clicks with bigger injectors. The stock GZE internals will handle it just fine, but his clutch probably won't.

A T3/T4 will do 20 psi, but be a lot more laggy that just a standard T3. What ends up happening is while the T3/T4 will be more efficient at high boost, it will be crap in the lower ranges. If he wants to redline the motor while dragging, a normal T25 or T28 will choke at the high revvs, even at 7psi. If he wants to freely rev in the top end, and have lots of power he needs a hot side (turbine) that will flow well. As a result, it will have more lag, but have more potential. A .63 will drastically move the boost onset up higher in the rev range, but it will allow him to go higher boost. It will be a progressive increase until the motor is about 4k then full boost from there to redline. Each shift shouldn't put it below 4k, and he will have lots of boost.

If he was doing short course racing, the GT28R(S) would be the ultimate because of its lower rpm response and resulting torque, but they're expensive. If he was doing track days (as in road racing), a 50 or 60 trim T3 with a .63 turbine would be good, as it would have a nice smooth increase in power.

The lag I was describing as beneficial does not apply at full throttle, but only in daily driving scenarios - if you're on the freeway, you don't want to be on boost just trying to maintain 70mph. You want the boost to come in at about 2/5 - 1/2 throttle so you have some decent economy.

[Luni]

Those are some good points. I wasnt sure how laggy a big T28 would be, I just know theyre awesome turbos and theyre not that "big" in terms of dimensions. Seems like a .57 or .60 hot side is gonna be what hes needin if hes gonna go with that. And yeah the GT28R is a killer turbo for tha thing, but GOD they ARE farkin expensive. Im sure theyre worth every penny but damn. They are expensive.

[CpuZapper]

OMFG... I can't believe the mistake I made in my last post... shame on me! I confused the title of big T28 - meaning just a large t28 form factor turbo - with the DSM "Big 16G" which is an aftermarket modded turbo like the CT27... Oops ^_^ Anyway, a T28 will still be hard-pressed for a reliable 20psi. I think before I go and babble like an idiot I should wait for 86mister2 to respond with what his budget and whatnot is. I mean, he can get a .60/.63 T3 for a $100-250 at a pick-n-pull and have a possible overkill turbo (hell, he may even want to just try an oil-cooled Saab or Volvo T3 just to see if he can even make it work), rather than spending the same amount on a turbo that won't hold up to the amount of power he wants to run. He could run one of the many billion Mitsu turbos, but if he wants reliablility, and ease of locating parts, the T3 is the form factor to use.

[TheAmazingDave]

I am very happy that you guys are willing to put so much time and thought into this. You guys are awesome!

Here's the scoop. I am rebuilding this engine ground-up. I have a 7 rib NA block in the garage. I will be using the GZE semi-forged pistons to bring static compression to a safe level, and I'm definately not in a hurry to crack cast pistons by demanding too much from them. The head is to be rebuilt to OEM spec. I will be using factory cams for the beginning, but I'll use adjustable cam gears for fine tuning. I will also be using the factory NA intake manifold and TB. ARP studs and bolts are to be used throughout, if nothing else just for piece of mind.

I know stock fuel isn't going to cut it. The stock ignition would probably be OK from what I've read, but the distributor and AFM are out of the picture in favor of coilpacks and a MAP sensor. I don't like how the USDM GZE ECU guestimates boost by monitoring incoming airflow and throttle position, that just seems sketchy, so stand-alone engine management will take over the job. Suggestions here are greatly appreciated, but I'm aiming at megasquirt 'n spark to do the job there. I still need to figure out the best size injectors to use. Perhaps 550cc? That's yet to be determined.

I've been reading back on my own posts, and I now agreee that it makes no sense to use this manifold I have, or at least in its current state. I would like to get a proper manifold (read: equal length runners) but I just don't know where to get one, especially an affordable one. I may be stuck with this log manifold, but if that is the case I will have it modified to work the way it should, no tearing up my car to make it fit. If I had any sort of fabrication skills I would make my own. Unfortunaley my poor math skills alone are making this project very difficult for me, I can't even fathom where to begin on parts fabrication. This is also why I'm having a hard time deciding the proper turbo to use, I see compressor and turbine maps and I get scared.

My plans for this engine are to put it into a street legal race car. I have decided to keep my 86SC because it now seems that I will not get the low-end response that I like and still pull off my top-end power goals with the turbocharged engine. The racecar will still be a comfortable daily driver, as in no excessive weight reduction, so I think 250-280 wheel ponies will make me a decent, if not serious, contender for drag nights and track days. This is going to be the car that I want to take to national MR2 meets and put on the tracks. While the SC will put down respectable numbers and performance, it just can't compete in races, I'm sure. It's great power to have fun on the street but that doesn't do me any good. I want to get into amateur drags, auto-x, and track events with the race car.

Thanks again for the help guys. I hope I'm not getting in too deep over my head.

[CpuZapper]

86mister2, why don't you give me a call... I've been at work all day, typing, and my carpel tunnel is killing me. I'll PM you my phone.