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Discussion Starter · #1 ·
Hey Guys, does anyone know, or are able to help explain the driveability and performance differences between the T3 stock turbo and the T3/T4 turbo? I was told that if I went to the hybrid turbo, I'd lose my low end torque, which may be true, but then again, looking at my driving demands on the engine, I always wish that I had more oomph at the mid to top end when I'm trying to accelerate on the highway.

on 0-60 times which would be faster? On 60 to 100+ times I'm guessing the hybrid is the way to go, but would there be a noticeable difference on the 1st through 3rd gear driving (hard accelerating)

Lastly, is it a straight swap on the compressor and turbine housing or do you need to get a specific turbine compressor one piece unit? (I have a water cooled central housing).... and does anybody know if the swap parts are easily purchasable...... or anyone with one that will fit the 85 TE car exhaust housing (the turbo does NOT have an integral wastegate)

The reason I'm even thinking about this is that my engine is right now being built into a monster with an S4S head and all kinds of other max performance mods to the engine, and I was advised to keep the T3 turbo on it.

Thanks,
Paul
94S4
85Te
 

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I don't know the specifics of the turbo on the S4, but my old Merkur XR4Ti had a T3 stock, put a garrett ballbearing T3/T4 turbo in it, and it spooled to set PSI (18 I think it was?) ~150 rpm earlier, till 500 miles later when the wastegate stuck and I hit 38 PSI... You can probably make up the rest of the story from there.
 

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Just saying it's a "T3" or "T3/T4" doesn't give enough information to form an opinion on. You'd also need to know the size and A/R of the turbine, and at least the size of the compressor.

For example, if you have a T3/T4 turbo using a .63 A/R turbine and, say, a t04E 46 trim compressor, it would be somewhat laggy on the 4-cyl Esprit (say, full boost at 4,000-4,500 revs), but be capable of lots of power (450+ hp)

However, if you have a T3/T4 turbo using a .48 A/R turbine and a 45 trim compressor, you'd have much less lag, at the cost of reduced turbine flow at higher RPMs and less potential power (in this case, still ~350 hp).

So, whether you have a T3 turbine with a T3 compressor, or a T3 turbine with a T4 compressor, you can pick a turbo that best suits your performance and drivability requirements regardless (to a point) of the turbine or compressor size.

It's also worth noting that the Garrett T-series turbos are a very old (though very good) design. The newer ball bearing turbos are much more advanced and can support a larger compressor without as much of a lag penalty.

If you want the street turbo from hell for a 4-Cyl, I'd go with a GT28RS with a largish turbine (say, .64 A/R) will have virtually no lag and produce 350+ hp. If you want more than that, something like a GT2871R will get you to 400 with a slight lag penalty.

All depends what you want out of the engine. :)

If you're building a monster engine, toss the stock setup and roll a custom turbo that'll make the power you want with the lag you consider acceptable.
 

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For a engine larger then 2.0L I would definantly do a T3-60 or a small T3/4 over a standard T3. They do not push enough CFM to make mutch power & since you are over 2L's lag isn't much of a issue anyways. But like Simba stated.... they are OLD technology..... ATP turbo does have T3/4 ball bearing turbo's that you might want to consider.... no clue on what models they have & how they work but it might be worth a look. BIG difference between the old journal bearings & the newer ball bearing designs!!

Presently my non lotus 2.0T uses a GT3071r & I get 22PSI at 3700 RPM's & 12PSI at 2000 RPM's. From what I have seen with GT2871r vs GT3071r, the 2871r actually has more lag then the 3071r both with the same A/R. The GT28rs (disco potato, designed for the evo8's 2.0T) is a awesome turbo however sometimes people complain about the boost coming on to fast on larger displacement 4 cylinder engines creating a big torque hit...... in my car torque kills my trannies & I beleive the esprit trannies aren't much better.

Many people also use I beleive Haldex turbo's which are suppose to develop similar power & also power curvs vs GT turbo's. Except they are rebuildable & also a lot less money.
 

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Discussion Starter · #5 ·
Thanks for the info guys.


It looks like I'll need to have quite a learning curve in order to get it right.

Does anybody have advice as to if I could use my turbo turbine (exhaust) and center water cooled housing, and then just change the intake compressor, and how much that might cost? Or is there a used (or rebuilt) reasonable turbo out there that would just bolt right on to replace my turbo (the car is an 85TE). Do any of you guys know someone who has the parts I could buy?(I'm assuming I will have to also balance the turbine/compressor wheel if it gets changed also).

I really would like to get more overall power potential. Also, in case it has any bearing, I'm running carbs(Dellorto 40's) and have a huge water to air intercooler (see attached pic)so if anyone has any idea on which size jetting, throat venturis, etc, for maximum power. I'm not necessarily interested in mpg or in smooth running at idle.

Thanks,
Paul
(951)206-9156
<img src="http://i96.photobucket.com/albums/l192/amorphicaura/Owners_paulw_09.jpg">
 

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It looks like I'll need to have quite a learning curve in order to get it right.

Does anybody have advice as to if I could use my turbo turbine (exhaust) and center water cooled housing, and then just change the intake compressor, and how much that might cost? Or is there a used (or rebuilt) reasonable turbo out there that would just bolt right on to replace my turbo (the car is an 85TE). Do any of you guys know someone who has the parts I could buy?(I'm assuming I will have to also balance the turbine/compressor wheel if it gets changed also).


Thanks,
Paul
(951)206-9156
Paul,


Contact Jamie at MJM Turbos (link below) for answers to your questions...He has owned several Loti over the years (both 4 cyl and V8) and he really knows his stuff. (along with John Welsh)

=| Insatiable need for speed |=
 

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Does anybody have advice as to if I could use my turbo turbine (exhaust) and center water cooled housing, and then just change the intake compressor, and how much that might cost? Or is there a used (or rebuilt) reasonable turbo out there that would just bolt right on to replace my turbo (the car is an 85TE). Do any of you guys know someone who has the parts I could buy?(I'm assuming I will have to also balance the turbine/compressor wheel if it gets changed also).
The CHRA (Center Housing Rotating Assembly) is basically the heart of the turbo. It has everything that actually matters. Its really what your gonna want to upgrade. Since the turbo is a Garret T series, you "should" be able to find a compatible turbo quite easily. Thats assuming it uses standard flanges for that turbo. Also if you go to a ball bearing turbo, you might need to take into consideration a oil pressure restrictor on the oil feeding the turbo, the ball bearing turbo's dont need as much oil flow as the thrust bearing turbos.

For a general idea of turbo costs, you can check out AGP Turbo's website
 

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stay away from t3/t4 anything...i've used them for years and put the last one to sleep on tuesday...good riddance. go garrett gt series..more linear boost delivery and faster spooling with lower egt's IMHO
 

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I've road raced a 2.3l turbo for nearly twenty years. The engine went through a long step by step developemental process and I can tell you this-the turbocharger is to be treated as any tuneable component. What works for one guy may not work the same for the next. It may work, but not with the particular results that you are looking for. I have used a number of configurations over the years, most of which were hybrids. I initially followed the lead in World Rally configurations to obtain good response and long flat torque curves. In one config, my car actually felt NA, with snap throttle response but it would make a little too much exhaust temp. Remember, what ever you do, there will be some level of compromise; there is no magic bullet. Every aspect of the turbo is tuneable ; compressor size and map,turbine size and map and a/r, and to a lesser extent the chra. Extra time for research is time well spent. There are a number of good resources out there. If someone perscribes "the fix" for your app, take their suggestion and scrutinize it to death. I've seen many folks misled and wind up with unsatisfactory results and worse-a major failure...IMHO.
 

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Simba said almost exactly what I was going to say.

T3/T4 doesn't mean anything. You need to know the A/R and compressor to know how the turbo will perform.

You will also need to know what kind of turbo it is, whether it be ball bearing, dual ball bearing, or even the new triple ball bearing. The T-BB hasn't been around for too long, so I don't know a single thing about it.

As stated, the GT28RS series turbo would probably be best for you. I believe it is a dual ball bearing so it will have awesome spool and response times (if you plan on staying twin turbo). Are you thinking of going single turbo? If you want to go single turbo, you could look at a GT35R or larger. They would make substantially more power, but at the cost of lag. The lag really isn't that bad, because if you shift high up in the RPM's you won't have lag when you get back on it. However, if you want to cruise at highway speeds and have power at any RPM and any gear, you won't have as much power lower down.

Just to make you feel better, there are many DSM people that run the GT35R turbo and once you are out of the lag, and shift high up, there is no problem. Keeping in mind that they are only 2.0L, and you have a much bigger engine to work with.
 

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Discussion Starter · #13 ·
OK, thanks for the advice. As to the previous post, I don't have a V-8, since it is a 1985 G-car.

I guess I should be a little more specific about the turbo. I right now have a water cooled turbo, which I don't know if it is a bearing or sleeve type core. The turbine and compressor are stock/standard off of up to 1988 or 1990 I believe.

I was looking to see cost wise, what would be the best power upgrade to do that would be either 1: straight swap and bolt on, or take my existing turbo and rebuild it with different parts.

I usually drive pretty peaky (from 3000 rpm up to limiter). I would really like to see the most performance from the type of driving where you are on the freeway at 85 mph or so, and downshift to 4th and punch it for a protracted acceleration run.

Also, if anyone has any idea as to the costs of parts (I do all my own labor) that would give me a good budgeting range as well.

Thanks,
Paul
 

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Okay in that case then the GT28RS would be fine for you. I believe they start around $1000 and go up to about $1400.

What ever turbo you do get, make sure you get the largest wastegate option for it. You might also want to have it ported for even better spool and response.

You should also look into getting a more efficient intercooler and piping. Believe it or not that will actually change things quite a bit.
 

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Discussion Starter · #15 ·
Hey Seb,

The picture below is of the top of my engine with the intercooler and piping showing. As you notice, this is not the stock setup. The next picture shows the extra NACA ducts I cut into the body which leads to two more fan cooled radiators for the intercooler (combined with a large radiator in the nose of the car as well for a total of 3 radiators)

How could I improve on this setup for intercooling? (Other than to go to something exotic like water injection, or freon based cooling)
<img src="http://i96.photobucket.com/albums/l192/amorphicaura/Owners_paulw_09.jpg">
<img src="http://i96.photobucket.com/albums/l192/amorphicaura/Owners_paulw_03.jpg">
<img src="http://i96.photobucket.com/albums/l192/amorphicaura/customLotusEsprit-1.jpg">
 

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You could do a water to air cooler, so you can fill it up with ice water and all that good stuff.

I don't know enough about your car to know what would be adequate, and the water to air would probably be overkill.

Stick with what you have, looks like you know what you're doing.
 

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Discussion Starter · #17 ·
Hey Seb,

What you are seeing in the pictures IS a water to air intercooler (chargecooler)
From empty to full, it takes several gallons of water/coolant. The pumps are electric Bosch units, and pump water at about a faucet running volume. There is also (not shown) heat insulating ducting which goes around the chargecooler which is fed by cold air from the left side rear window vent (which Lotus never used.... don't ask me why)

The engine is a built S4S head with adjustable position exhaust and intake pulleys, high lift performance cams, crank ignition, coated exhaust and turbo manifolds, forged 7.5 to 1 pistons, Nikasil liners, balanced rebuilt crank, twin DellOrto 40's carbs. The wastegate is the separate unit which sits under the exhaust manifold and is adjustable to any psi... currently running about 12 psi.
The exhaust runs with NO cat to the first set of resonator tips, then continues to the second set of tips via a small cat. (Smog check test tube put in the right exhaust pipe works like a charm :)
The last picture is of how I made a cup and screw assembly to fit into the stock Lotus supplied wastegate to make it fully adjustable.

Paul

<img src="http://i96.photobucket.com/albums/l192/amorphicaura/IMG_1451.jpg"><img src="http://i96.photobucket.com/albums/l192/amorphicaura/IMG_1449_1.jpg"><img src="http://i96.photobucket.com/albums/l192/amorphicaura/IMG_1453_1.jpg"><img src="http://i96.photobucket.com/albums/l192/amorphicaura/exhaustpipes.jpg"><img src="http://i96.photobucket.com/albums/l192/amorphicaura/Owners_paulw_08-1.jpg"><img src="http://i96.photobucket.com/albums/l192/amorphicaura/wastegatemod.jpg">
 

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I guess I should be a little more specific about the turbo. I right now have a water cooled turbo, which I don't know if it is a bearing or sleeve type core. The turbine and compressor are stock/standard off of up to 1988 or 1990 I believe.
Almost certainly a journal bearing. Whether the turbo is water cooled or not doesn't really have anything to do with the bearing type. Both journal and ball bearing turbos can be had with or without water cooling.

I prefer water cooling as it really helps prevent oil burn on the bearings, and hence is a little more forgiving if you don't turbo time as much as you should on occasion.

I was looking to see cost wise, what would be the best power upgrade to do that would be either 1: straight swap and bolt on, or take my existing turbo and rebuild it with different parts.
In my experience, rebuilt turbos are never anywhere near as reliable as a new unit, so while the savings of a rebuilt hybrid setup on a stock housing may be attractive price-wise, it stops being so if the turbo craps itself inside of 5,000 miles.

Personally I'd go with a new BB turbo.

Also, if anyone has any idea as to the costs of parts (I do all my own labor) that would give me a good budgeting range as well.
If you want to do a GT28RS, which is what I'd do on that engine, you're looking at ~$1,150 for the turbo, and probably another $2-300 or so for the ancillary fittings and flanges to fab up a system. Add probably another $250 to that if you want an external wastegate, which for me at least, is worth its weight in gold from a boost consistency standpoint. Alternatively you could stick with the Lotus wastegate setup if you're happy with it.
 
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