Jesus
February 23, 2006, 9:28 pm
Be very careful when picking your turbo.
You need to plan right now where you want to go with it.
Do you want a car for the drag strip, which will do a 1/4 in the 11's... or do you want a very fast car for the road?
Drag strip prepared cars usually come on to power very late in the rev range and up until about 4500 revs you'll be very flat. Once on full boost though it will be as quick as you like.
Personally, I'd sooner go for a very fast road car, with plenty of torque and responsiveness.
Ignore what bhp figures you get given to make your decision on... find out where abouts in the rev range that power is. Makes one hell of a difference. Speccing up the right turbo for you is science in itself, and not a decision to rush into.
With regards to the intercooler... yes. I noticed a significant difference with the HKS intercooler I have, and that is only tube and fin design instead of bar and plate. Bar and plate has more thermal mass and can dissipate the heat quicker.
Admittedly, our custom pipes made the most difference, due to airflow, pressure drop resilience and relocation of the BOV to near the throttle body (no need to re-pressurise intercooler when going back on boost after it's all been dumped).
Also, don't forget that the GReddy intercooler may be optimally sized for the CT26 or CT20 turbo... but beyond that you may need a larger core (difficult on MR2 I know without going boot mounted).
I'd certainly recommend using water/methanol injection. Paul Port's kit is amazing. Bibbs has been singing it's praises for years... and I eventually got round to getting it fitted by Paul. I'm currently running 1.3bar on the stock turbo (CT20b)... and my throttle body charge temps never exceed 30oC no matter how long I've been on boost. You know what your car runs like on a cold, misty night when the air's dense?... well imagine that all the time when on boost.
I can't emphasize enough the importance of cooling.
With regards to the manifold and downpipe (more so the manifold) you need to find out what affect it has on the power/torque band.
Also, check the history of products to find out if there are any nightmare stories. I've heard of a few of ebay that end up cracking pretty quickly. Obviously it's stainless, and hence more prone to crack around the welds than the stock cast iron manifold.
You'd probably be better off taking the stock manifold off and having it polished and ported. Obviously, you only make the best out of this work if you've also had the head done, and the inlet manifold.
With regards to forgies etc, as long as you're keeping your charge temps low, there's no reason to suspect standard piston meltdown (as long as fuelling is also set up right). Obviously you'll be safer, and will be able to run more boost with forged pistons and uprated conrods... but it's not quite as straight forward as that.
If you're planning on going above probably 350bhp then it's certainly worth pricing up.
That's just a taster for you anyway Jim... obviously there's a lot more to consider...