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Rebuilt CT20 and a new TB developments down pipe installed!
So many poor driving characteristics have gone after this and i have noticed a significant difference in drivability.
The down pipe from Timothy Bill not only looks superb but performs amazing too! I am running stock actuator pressure which is 7psi and as some know ct20s suffer from over boost / boost creep with a super free flowing exhaust system, but the design of the downpipe has helped control it keeping boost at 7-8psi steady (I saw peaks of 14psi with my old downpipe and turbo!)
I will reinstall my manual boost controller soon and get her back on a dyno to see if my previous tired turbo and super cracked downpipe was indeed the cause of my pathetic 204bhp @18psi!
I can't figure out how to put in an image here, so this is my cry for help.
Would have pulled the stock exhaust manifold off while you were at it, it can really do with some port matching at both ends. The matching at the turbo is especially bad when you compare the possible best match with the gasket. The CT20b turbine housing is probably no better than the CT26 with the match either. Also worth checking that its not warped as well. Every single one of the earlier versions are warped like a banana.
Nice looking downpipe but probably still needs a support bracket fitted near the flexi. Stainless is a brittle as and it will still crack unless you take some strain off it and restrict the movement near the flexi.
MR2DI4 wrote: ↑14/09/21 23:17
Would have pulled the stock exhaust manifold off while you were at it, it can really do with some port matching at both ends. The matching at the turbo is especially bad when you compare the possible best match with the gasket. The CT20b turbine housing is probably no better than the CT26 with the match either. Also worth checking that its not warped as well. Every single one of the earlier versions are warped like a banana.
Nice looking downpipe but probably still needs a support bracket fitted near the flexi. Stainless is a brittle as and it will still crack unless you take some strain off it and restrict the movement near the flexi.
In regard to your comments, the manifold was all checked for warping and was all good before going back on.
The manifold probably could do with porting, but I've heard many people have had good results with them nonetheless. It's just more money I don't want to spend right now, as I just want to make more than 204bhp @18psi boost.
The downpipe came with a support bracket for the bottom, i suspect that is why my previous one almost came out in 2 parts!
I can't figure out how to put in an image here, so this is my cry for help.
Only 204Hp at 18psi makes no sense at all to me really.
However, like I have said before, pressure is not the same as flow. Its possible to be getting more actual air into the engine at 15psi as it is at 18psi if you think about it. There are restrictions in the intake and the exhaust path.
Cannot really see the new turbo fixing the problem unless the old one was knackered to the point it needed to have the wastegate fully closed to get 18psi out of it. The CT20b doesn't produce a whole lot more than 18psi anyway, maybe 21-22psi. 18psi doesn't really indicate to me the turbo was totally stuffed.
Its hard to see the problem is only the turbo but I guess another Dyno run will confirm it.
I guess its possible the added exhaust restriction of the wastegate not opening as far as it should at 18psi could kill off at least 20Hp.
Last edited by MR2DI4 on 15/09/21 23:43, edited 1 time in total.
MR2DI4 wrote: ↑15/09/21 22:50
Cannot really see the new turbo fixing the problem unless the old one was knackered to the point it needed to have the wastegate fully closed to get 18psi out of it.
The old one would smoke alot, was defo laggier than this one. so i want to say it was on its last legs if anything.
I can't figure out how to put in an image here, so this is my cry for help.
My old CT26 smoked for years when you first hit boost, the seals in it were stuffed very early on mine due to poor oil choice and not changing it by the first NZ owner. Unless you run a full synthetic oil in the MR2 turbo the seals don't last and it carbons up badly in the bottom of the Exhaust turbine seal grove. Mineral oils simply cannot handle the temperature in the exhaust turbine area. The CT26 and CT20b don't fully stuff out until the floating bearings wear to the point the compressor wheel starts rubbing on the case and then its game over pretty quickly after that.
The forum Administrator has chosen to advise you that this topic is 2 years and 7 months old and that you may wish to begin a new topic or use the search feature to find a similar but newer topic.
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