SaabCentral Forums banner
1 - 13 of 13 Posts

·
Registered
Joined
·
205 Posts
Discussion Starter · #1 ·
Curious as to if anyone has ever successfully done or atttempted to change a t7 1999 viggen over to t5? If so did anything special with the wiring inside the car have to be done to make all the computers communicate happily
 

·
Registered
Joined
·
131 Posts
I imagine that you would have to swap an entire T5 wiring harness from a 99 9-3 over. Along with that you would have to replace the intake manifold, throttle body, throttle cable, charge pipe, DIC, and all the associated sensors. You would also need to tune the t5 ECU for a 2.3 setup. Aside from being able to run a BOV I don't really see any benefit of downgrading the engine to T5.

Any particular reason you want/have to do this? Having driven both stock and tuned T5 and T7 setups I honestly prefer the refinement of T7 despite the additional complexity.
 

·
Registered
Joined
·
12,793 Posts
You can't just replace the intake manifold, the T5 manifold and T7 head (or vice-versa) don't line up. You would have to build a custom manifold.

Are you looking to swap in a complete T5 engine? I can see the benefits of that (stronger internals, less prone to sludging, etc), but normally people keep the T7 system and just change out the engine, though the same caveat as above still exists.
 

·
Registered
Joined
·
205 Posts
Discussion Starter · #4 ·
I imagine that you would have to swap an entire T5 wiring harness from a 99 9-3 over. Along with that you would have to replace the intake manifold, throttle body, throttle cable, charge pipe, DIC, and all the associated sensors. You would also need to tune the t5 ECU for a 2.3 setup. Aside from being able to run a BOV I don't really see any benefit of downgrading the engine to T5.

Any particular reason you want/have to do this? Having driven both stock and tuned T5 and T7 setups I honestly prefer the refinement of T7 despite the additional complexity.
The sensor and mechanical portion im not worried about and I already have a t5 harness. my motor is actually a 2.3 block out of a 9000 with a t7 head and a bunch of goodies. I was more curiuos as to the connection to the body harness and communication amongst the anti theft and obd2 stuff. Im looking to upgrade the gt28 i have and run either a gt30 or holset without having to change the exahsut manifold itself to the top mount. My gt28 fits pretty snug and piping the 3 inch intake around the water pump to run the maf was a bit difficult. the gt30 im looking into has a 4 inch lnlet hich means ill have to run a bigger intake setup and may throw off the maf readings since the maf is only 3 inch. t5 is also easier to tune in my opinion without all the complexity of a t7 setup. I have all the parts available at no cost just exploring my options as well as seeing if it has been done
 

·
Registered
Joined
·
205 Posts
Discussion Starter · #5 ·
You can't just replace the intake manifold, the T5 manifold and T7 head (or vice-versa) don't line up. You would have to build a custom manifold.

Are you looking to swap in a complete T5 engine? I can see the benefits of that (stronger internals, less prone to sludging, etc), but normally people keep the T7 system and just change out the engine, though the same caveat as above still exists.
ive actually already done this i have a t5 block from a 9000 with a t7 head
 

·
Registered
Joined
·
205 Posts
Discussion Starter · #7 ·
Then there is no benefit or need to change to from T7 to T5 systems.
Just note that you will have a loss of compression with the hybrid block/head combo.
the reason im looking to change it is to fit a larger turbo and not have to worry about fitting a 4 inch intake around my water pump , i currently run the hybrid motor setup now on t7 with a gt28 im looking to go for bigger power
 

·
Registered
Joined
·
205 Posts
Discussion Starter · #9 ·
How will changing the engine management system give you more clearance at the water pump?
i wont have to run a full intake for the maf i can throw a filter right on the compressor or screen it for when i track it. it eliminates the need for piping from there up to the maf. but aside from why im doing it im just trying to see if its possible
 

·
Registered
Joined
·
12,793 Posts
Understood, there is the option of moving the MAF to the other side of the IC.

To answer your original question, the T5 harness is pretty standalone, but you will likely need to grab some extensive wiring from the inside too, since the clusters are different for the T7 and T5 cars.
 

·
Registered
Joined
·
1,274 Posts
If you plan to swap over the t5 engine you will have lots of fun fabrication, if you plan to use t5 get ready to re wire the whole car, cruise control, the throttle body and the power steering pumps are all different.

Making a hybrid works if you use the b204 bottom end and a t7 head reusing all of the t7 accessories it works out perfect, if you choose a b234 with a t5 headgasket you need to mill the pistons down or else the compression ratio drops down, if you use a t7 headgasket with no milling you will have valves contacting the pistons.

Do yourself a favor and build the t7 engine ( forged pistons ) there is nothing wrong with the management plenty of people have made 500+ hp with it.
 

·
Registered
Joined
·
841 Posts
It's not impossible, nothing is. But swapping a t7 car to the t5 ecu would be more trouble than any amount of mechanical work setting up an intake to work with the t7 MAF. You would need to work out how to bridge the non-engine related pins for the ECU into the car chassis wiring and then work within the software to get the t7 chassis electronics talking to the t5 ecu. no small feat.

I don't want to sound too negative because I love this kind of outside the box thinking, but are you sure the larger turbo fits in the stock location, regardless of intake?
 
1 - 13 of 13 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top