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Hello,
What parts are required for a 2.5L TIII conversion beside the head and manifolds.
I read :
- 2.5L custom pistons,
- intermediate shaft sprocket,
- passenger side mount,
Can I run the stock electronics, will the distributor hit the intake ?
If I use TIII electronic, what parts do I need (harness, ECU flashed, trans sensor) ?
thanks
I've built a 2.5L TIII, so I'll take a crack at this.
First of all you should know I did it from an existing 2.2L TIII. I simply bought Venolia pistons from FWDP and used a cast 2.5L crank. That was about it. I have another engine ready to build, but this time with Wiseco pistons from TU. So there are options.
In both cases, I'm starting from a TIII block. I can't speak to the drivability or any other factor because I haven't yet got them running yet. The venolia piston'd engine is going into my '91 Spirit R/T and will be running stock electronics for the break-in at least. From there, I don't have high expectations of it. I'm mostly wanting a fun street car with low/stock boost but with a Buick GN turbo. I put it together with a Cometic head gasket though. I'm mostly looking forward to having the revs of a TIII AND the low end torque of the 2.5L. Nothing more... I'm not a drag racer or anything like that. It's mostly nostaglia for me. I kind of come from the pizza delivery guy standpoint of having something drivable and reliable.
For me the bad news come from the pistons : do I really need custom pistons (too low compression) and do I have to bore my block to use forged one ?IIRC, forged pistons require more wall clearance right ?What are the differences between the venolia and wiseco ?Do the intake allows to use the distributor ?What other parts I need (upper water nose ? engine mount ? ) ????
Ok, so to run an SMEC 2.5 TIII, you need few things.Quote:
Originally Posted by nvysion
TIII cam gears/idlers/powersteering bracket and pump, passenger mount bracket or you have to clearance the 8 valve one as it hits the cam gear.
If you run the dizzy, you either run it backwards on the exhaust cam with a custom plate like I had done or you modify the intake to clear the dizzy but then you need a custom intermediate gear or use the 8 valve and delete the idler timing pulley. You'll have to extend some wiring but no biggie.
Stock 8 valve pistons will net you low 7's for compression, so either accept that or use proper pistons. I think the Wiseco's are a better piston BUT they use a unique ring, Venolia's use a normal ring pack.
You'll also need the complete intake, fuel lines etc, thermostat housing and other bits and pieces. Honestly, its easier to buy a core engine or running engine and use that.
To run a SBEC, you'll need a SBEC wiring harness, its all plug and play, just some wires need extending, the proper TIII flywheel, cam and crank sensors and a TIII SBEC.
I have a build thread that shows how I did it, adapters etc I had made and can get made. I also have an aftermarket elbow that bolts on a T3/T4 so you can use the stock DP, which is the same between all the cars.
Thanks for these tips.
Could you explain me this :
"or you modify the intake to clear the dizzy but then you need a custom intermediate gear or use the 8 valve and delete the idler timing pulley. You'll have to extend some wiring but no biggie."
Why would I have to use a custom intermediate gear with the stock disributor or delete the idler timing pulley ?
Do you have a link to your thread ?
I understand that if the TIII crank gear has the same number of teeths than a 8V one that implies that I must use :
- a 8V intermediate gear or
- a TIII one if it has the same number of teeths as a 8V one
otherwise distributor would not work.
I have read contradictory posts, some telling that the 8V and 16V pitchs are different for the timing belt.
I also read that the 16V timing belt is wider so the edges of the intermediate gear must be ground off.
BTW what is the idler timing pulley (is it the timing tensionner ?) ?
If you use TIII electronics, you could potentially use either the TIII or regular 8v intermediate sprocket. With TIII electronics and the fact that I-shaft doesn't run a distributor, the diameter of the I-shaft gear isn't a problem as far as ignition timing. However, the oil pump would run a little slower vs engine RPM with the larger 8v gear and also the tooth profile isn't the same between TI/TII and TIII. TI/TII or either round or square and the TIII is more trapezoidal in shape.Quote:
Originally Posted by nvysion
Personally I would recommend going full TIII everything if you do it. Hopefully for you and me a 2.5L TIII cal will become available eventually.
Thanks
Quote:
Originally Posted by iTurbo
Right now I only have the ECU and not the harness, and even so, I would prefer stay with the 8V electronic because I"m very limited with what I can do myself.
Can I still use the 8V intermediate gear and crank gear with the 16V timing belt or the profile and width are two different between 8V and 16V?Quote:
Originally Posted by iTurbo