T78 to 35/40 Possible?
09-04-02, 10:41 PM
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T78 to 35/40 Possible?
I have the opportunity to pick up a T78 kit very inexpensively. It's such a good deal that I can't pass it up. I'd like to see how this turbo behaves in stock form on the street. If I'm not happy, would swapping in a GT35/40 be feasible? I know the 35/40 is a T3 frame, not sure what the GReddy is or if there's an adapter available. I suppose, push comes to shove, I could have a machine shop whip something up. Also, Gordon, if you have the time, could you explain what you've done to your T78 (changed from the stock GReddy setup)? Advice appreciated.
09-04-02, 11:02 PM
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Right. I'm assuming the downpipe will need massaging and such...everything else should be there though. The 35/40 has a coolant/oil feed if I remember correctly and the T78 is oil only? I wonder...does the T78 kit route the wastegate dump back into the downpipe?
michel
michel
09-04-02, 11:02 PM
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Re: T78 to 35/40 Possible?
as fourty stated.. an adaptor plate would be needed from T04 --> T3 ... one problem you might run into is that the with the adaptor plate you might have some clearance issues with the hood... clocking the turbo will only give you so much room, add an adaptor plate now your even tighter
good luck
good luck
Originally posted by rx7tt95
I have the opportunity to pick up a T78 kit very inexpensively. It's such a good deal that I can't pass it up. I'd like to see how this turbo behaves in stock form on the street. If I'm not happy, would swapping in a GT35/40 be feasible? I know the 35/40 is a T3 frame, not sure what the GReddy is or if there's an adapter available. I suppose, push comes to shove, I could have a machine shop whip something up. Also, Gordon, if you have the time, could you explain what you've done to your T78 (changed from the stock GReddy setup)? Advice appreciated.
I have the opportunity to pick up a T78 kit very inexpensively. It's such a good deal that I can't pass it up. I'd like to see how this turbo behaves in stock form on the street. If I'm not happy, would swapping in a GT35/40 be feasible? I know the 35/40 is a T3 frame, not sure what the GReddy is or if there's an adapter available. I suppose, push comes to shove, I could have a machine shop whip something up. Also, Gordon, if you have the time, could you explain what you've done to your T78 (changed from the stock GReddy setup)? Advice appreciated.
09-04-02, 11:03 PM
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Hrm...didn't consider that one. I have a SMIC too which may make it even more difficult. Still, for the price of entry here, it's too good to pass up.
Michel
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09-04-02, 11:39 PM
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Well I could get the T78 kit for about $1500 LESS than a new 35/40 kit and the 78 kit is practically new. If I'm happy with the performance of the GReddy kit then great. If not, I'll just sell the 78 and get a 3540 or straight 40. Either way, I'll end up ahead cost-wise. I have an upgraded diff and clutch disk on the way and I haven't had time to do any sort of roadrace, just drag stuff and this turbo will probably work well for me for the time being. Truth is, I'd rather have the 35/40, but I can't ignore the cost savings. :-) I'd also like to field an "unbiased" testimonial of what it's like to go from sequentials to a supposedly laggy turbo to the 35/40. Might be fun!
Michel
Michel
09-05-02, 08:31 AM
#10
I think the "spool" or "lag" or even "turbo response" has been greatly exaggerated about these turbos.
Both the T78 and GT turbos are excellent in their response and lag. Most (if not all) are not racing for a living and counting milliseconds as gold. When tuned properly, both turbos will make most of us speed freaks happy.
Stick with the T78 and save the extra cash for your girl or race fuel =o) and track time.
Gordon has already posted many times the different dyno plots from various turbo set-ups. These dyno plots all look very similar in maximum output and lag.
I've done the T4 to T3 adapter and let me tell you, get a kit. It's cleaner and nicer. I wanted to play around with the welder and fabricate my own parts, so I chose my route for installation.
some Gory details on adapter fitting:
You'll need to weld the adapter on the manifold flange unless your manifold has easy access to the backside of the flange so all the studs for the adapter can easily fit (I doubt Greddy manifolds have this access).
The adapter will run about $120 or so.
I used it with the HKS SS T04 manifold and my GT35/40 barely fits (compressor housing is almost up against the frame rail).
alternatives:
T78 with a smaller turbine housing will give less lag if you're REALLY concerned about it.
Seriously, I have to mention that lag is overrated with most single turbo set-ups (unless you're talking about T100). You won't have better lag and torque curve than the stock twin turbos. Your power output should be significantly greater though
J
Both the T78 and GT turbos are excellent in their response and lag. Most (if not all) are not racing for a living and counting milliseconds as gold. When tuned properly, both turbos will make most of us speed freaks happy.
Stick with the T78 and save the extra cash for your girl or race fuel =o) and track time.
Gordon has already posted many times the different dyno plots from various turbo set-ups. These dyno plots all look very similar in maximum output and lag.
I've done the T4 to T3 adapter and let me tell you, get a kit. It's cleaner and nicer. I wanted to play around with the welder and fabricate my own parts, so I chose my route for installation.
some Gory details on adapter fitting:
You'll need to weld the adapter on the manifold flange unless your manifold has easy access to the backside of the flange so all the studs for the adapter can easily fit (I doubt Greddy manifolds have this access).
The adapter will run about $120 or so.
I used it with the HKS SS T04 manifold and my GT35/40 barely fits (compressor housing is almost up against the frame rail).
alternatives:
T78 with a smaller turbine housing will give less lag if you're REALLY concerned about it.
Seriously, I have to mention that lag is overrated with most single turbo set-ups (unless you're talking about T100). You won't have better lag and torque curve than the stock twin turbos. Your power output should be significantly greater though
J
09-05-02, 09:29 AM
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http://www.hksusa.com/products/?id=828 and a new downpipe and you should be set
09-05-02, 12:03 PM
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I've been thinking along those same lines, save the extra $$$ and put it into something else, like water injection and a roll cage :-) I was looking at Greddy's Japanese site (Trust-Power.com) and did notice they have different turbine sizes for the 78 and the 88 so I may look into that down the road if I'm not happy with the stock T78 setup. Thanks for all the advice!
Michel
Michel
09-05-02, 09:29 PM
#13
Greg,
The adapter flange is not bolt on at all with some (maybe most) of the aftermarket exhaust manifolds. Look at the backside of the turbine (T04) flange on the manifold and you'll see that you can't easily put the studs through since the tubes from the exhaust manifold bend real close to the backside of the flange.
If you have a custom exhaust manifold where it is easy to insert the studs and torque the nuts down on the backside of the flange, then you can bolt it on.
However, depending on design, it may push the turbo into the frame rail.
J
The adapter flange is not bolt on at all with some (maybe most) of the aftermarket exhaust manifolds. Look at the backside of the turbine (T04) flange on the manifold and you'll see that you can't easily put the studs through since the tubes from the exhaust manifold bend real close to the backside of the flange.
If you have a custom exhaust manifold where it is easy to insert the studs and torque the nuts down on the backside of the flange, then you can bolt it on.
However, depending on design, it may push the turbo into the frame rail.
J
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