View Full Version : Beginning a Turbo build, seeking Advice

08-05-2004, 07:43 PM
Okay, I'm planning a turbo buildup for my 1990 240SX xe w/Ka24e. I've got some questions and hopefully some of you can help because turbo knowledge is in short supply in my area.
first the basics: the car is solid, and the motor runs well at 183,000 miles. I bought it about 1,000 miles ago and have no idea what kind of history it's got. it does have the Timing chain rattle on startup, but I've dealt with that before on ka's in trucks. next, I am an Auto Mechanic, working towards ASE certification. I have access to all the manuals, diagrams, tools, and equipment needed for just about anything. I also have good computer skills and some basic electronics experience.
now for the fun part-what I dream about at night. I want to have around 300hp. my basic math says about 14 psi boost should do it if effieciency is improved in other areas as well. nothing crazy, but it has to be reliable and start every time I turn the key. I realize that much of this has to do with the tuning. not a problem again-my boss has tuned several boosted cars before, he's just never designed a system from the ground up and can't tell one axis of a compressor map from the other.
now the questions-my basic math shows I need about 500 cfm at a PR of 2, at 85% VE, and a 7000 RPM redline (remember, nothing crazy here) next, I'd like to have full boost at 3000 rpm. I want to be able to switch to a lower boost setting, around 7 psi for normal street driving. finally, I'd like to do this on 93 pump gas. I have no problem "spiking" fuel with octane booster, but I don't want to unless it's the only way.
after looking around at http://www.turbocalculator.com/, I found the super T04E turbos. a Super T04E-54 puts me between 70% and 72% percent efficiency. a Super T04E-57 is between 67% and 71%. either way I go I want to use an internal wastegate. my big question is: how do I decide which A/R ratio to use? both 0.48 and 0.63 are available, but I don't want it to spool so fast that it surges. help in this area is greatly appreciated.
next is the engine-it never smokes, but should I at least try to run stock pistons before buying better? will the head gasket hold at 14 pounds boost?
moving along to engine management-my first choice is a megasquirt unit, mainly because it's cheap and powerful. the downside to this is that it has no control over ignition timing, requireing a standalone ignition setup-possibly MSD ignition system w/boost-timing retard? I want to keep the factory dash as-is, so I think the stock computer has to at least be tied to all the main sensors, even if it has no control over anything. Am I wrong? are there any other suggestions for a cost-effective EFI control systems?
finally, has anyone had experience with the Phantom Grip Limited Slip that Jeg's sells? It goes for $290 instead of $1000+ for a japenese unit.
thanks in advance for the help, it is appreciated.
Adam Lewis

08-05-2004, 11:45 PM
1st thing you should do is buy a ka24de motor, its an easy swap and worth it. next think about how much you want to spend-although it always works out that youll go over budget. you should so 300hp at 12 psi if you use 3" downpipe and exhaust, good size intercooler. i personally would suggest 3" charge pipe but many people will say no because 'no need' or 'youll get lag.'

08-08-2004, 01:03 PM
whoa, only one response. I expected more. anyways, I'm not really setting a budget, just a HP target. 12 pounds eh? thats good enough for me. anyways, I'd like to stick with my KA24E until I hit a limit that stops me from using it. as far as intercoolers go, I'm planning to build my own around a core. any recomendations on manufacturer?

08-08-2004, 01:59 PM
i could be wrong, but i believe the highest HP hit on a ka24e was sub 250hp.
I used to have a dyno video of the car. I think the consensus on this board w/ ka-t, is most run the twin cam motor.
They can be had for less $500 w/ tranny in most cases.

I think one of the main benefits of doing the swap is you, in most cases, get a lower mileage engine/tranny. Good luck on your build.

08-08-2004, 05:12 PM
it's not so much that I'm deadset on using a ka24e, it's just that it matches the car, and it's what I've got. if it's determined that I can't make 300hp with what I've got, then I'll upgrade. otherwise, it's just an added expense.

08-08-2004, 05:44 PM
If you engine is in good shape, there is not reason you can't make 300 with the E motor. I would think a stock E motor would be more boost friendly that a stock DE motor, assuming the pistons are made the same.

08-08-2004, 08:47 PM
where's Adam?! Input! Input!

08-08-2004, 10:32 PM
if that is the max, then I hope to pass it eventually. it seems rediculous that anyone would stop at 250.

has anyone ever built up a sohc block before. I intend on doing such, and would be well over 250 when I reached the limit of all of my components.

08-08-2004, 11:58 PM
Adam's web page (http://www.turbo240sx.ca/) ADAM HUTCHINSON on this board...