Which Turbo? Slight flaming allowed

[lovemy89240]

As the title says I'm looking for a turbo for my ca18det
My current set up is a T3/T4 hybrid with a .50AR cold side and .63AR hot side. 2.5 inch intercooler piping with the whole front of the car covered in intercooler, and a 2.5" exhaust.
The lag is pretty much unbearable and I don't hit full boost (8psi currently) till damn near close to 4500rpm. Now I don't wanna say that's horrible but the car falls on it's face at launch and 1st gears a joke (3:90 gears in the rear arnt helping either with the stock CA trans).

Now all searches end with either a t25 or t28 and the disco potato.
But I wanna stay oil cooled only and I don't really wanna stray from the 5 bolt down pipe, and the math equations for finding the perfect turbo for my engine is alittle to complicated for my math level...

My horsepower goal is around 250ish and I want as quick of a spool time as possible as this car sees alot of auto x and the occasional mountain passes and the drag strip, but I don't want the car to have horrible top end....
Now I know I can't have both but I want it as close as possible ha!

So any help is appreciated
Thanks

[TheMAN]

GT2854 gets my vote
basically a GT2554 with larger wheels... it's almost like a disco potato except it's not... it's smaller AR allows for quicker spool up with minimal top end loss
with a rev happy motor like the CA, it'll be perfect... it's good up to 25psi too

[boost_boy]

Switch to a .48 back housing. That .63 will cause you nothing but lag for a street car. To use that turbo, you have to have the car tuned to deal with the loss of power before 4750rpm. Change to the .48 and the turbo will much more fun.

[nickd0tc0m]

I second the .48 turbine housing. It'll be a lot more fun and cheaper than getting a different turbo. Also, do you really have an intercooler covering then entire front end of the car? How thick is it? Depending on the size; I'm assuming you could probably get away with something smaller and reduce pressure drop.

BTW, Nice headcrab!

[lovemy89240]

So the the .48 hot side seems to be the best bet, but is there a big top end difference between the .63 I have on the car and a .48 hot side?
And I love the ultra mega power rush I get when I hit 5k,
Will I Lose said rush with the smaller snail, or is that only the other 4 intake ports opening? (sorry it's my first CA)

And about the "whole front of the car covered in intercooler"
Its a mishimoto intercooler
It's 3" thick 12" tall, 22" wide at the bottom and 19" wide at the top
( keep in mind this is in a datsun 510, so it's from radiator support to floor, from headlight to headlight

Thanks guys
P.s. I love my head crab, her names russell

[boost_boy]

I'll get right to your questions, you don't need to worry about choking-off your top end performance by chosing the .48 housing. I've used them in the past and currently have one on my sentra with the GT30R and that thing is a treat throughout it's driving range. BTW, with the CA's ability to rev a little higher, you'd be amazed at what it can do on the top end. My 240/CA is equipped with a GT35R which is .63 on the rear and .70 on the front and that's considered rather large for our little engines. But that turbo is perfect for what I want because I don't want my rear-wheel drive car always trying to boost (SOME LAG) while I'm just trying to make the car go from point A to B, but guess what, the darn thing breaks the tires loose anyways; especially when it's wet. I tune my engine management system to assist the engine when it's off boost which means the car is not lazy even when it's not boosting (the beauty of a standalone). So it's all about what you want the car to do and when. Selection of the correct turbo and the correct housings play a pivotal role in you enjoying your investment.

[TheMAN]

if you're worried about top end power, improving efficiency in the engine itself will counteract the lower high RPM VE of the turbo... a set of cams, and bigger throttle body is a good start to make up for it... that being said though, I don't think it's an issue as boost boy pointed out, since the CA is rev happy to begin with

[float_6969]

For our motors, keep the turbine side small, but do things like mild cams and a port and polish to bring the top end back up. Combine those with some compentent tuning and you'll be happy with the results.

[lovemy89240]

Thanks guys for the suggestions, now I have an opportunity to get a brand new Precision SC5557SP Billet Turbo for super cheap, the only thing is it's only available with the ported "S" cover that's .70AR, but I have the option of a .48, .63 or a .82 AR hot side
now will the .70/.48 combo make for a wierd spool and boosting turbo or would my little 1.8L be able to use it affectively at a mild 10psi with nistune, 780cc injectors, walbro 255, FPR, 91 octane and a tuner who's very competent?

[float_6969]

.70/.48 combo will be fine, but 10psi isn't much on that turbo. Are you planning for more boost later?

[lovemy89240]

More boost is defiantly planed in the future, but not until I do a rebuild and the usual metal head gasket, arp fasteners, Forged wiseco pistons and pauter x beams...

But I am worried that I won't be using this turbo to it's fullest and will actually hurt my performance, but hey atleast it'll hurry me up to rebuild the engine!

[float_6969]

Not to mess with your plans, but as long as you've got good compression, the stock engine internals are good for at least 350hp, maybe more. A turbo that size only running 10psi is going to make for a little lag, but I think with those injectors, you'll be fine to turn the boost up more than 10psi and be fine. I'd run at least 15psi.

This is all assuming the compression is good. Have you checked it?

[lovemy89240]

To be honest I havnt recently checked the compression, last time I did was 2/24/10 when I bought it and if I remember correctly the readings after proper warm up dry test were all high 150-160 psi and the car is in the shop getting a new clutch, ka trans with swapped bell housing, rear main seal and oil Pan gasket.. (would have done it myself but work seems to love ruining my social life haha) but when it gets out tommaro that's the first thing I'll do


And i know the fuel system is up for more boost but isn't 15psi pushing the engine, even with good compression?

[boost_boy]

To be honest I havnt recently checked the compression, last time I did was 2/24/10 when I bought it and if I remember correctly the readings after proper warm up dry test were all high 150-160 psi and the car is in the shop getting a new clutch, ka trans with swapped bell housing, rear main seal and oil Pan gasket.. (would have done it myself but work seems to love ruining my social life haha) but when it gets out tommaro that's the first thing I'll do


And i know the fuel system is up for more boost but isn't 15psi pushing the engine, even with good compression?

Even with bad compression, the CA18DET can withstand more than 400whp, granted the engine management system is competent.

[lovemy89240]

Alright well I ordered the turbo .70/.48 should be here soon then I'll Try to hit the garage by January and see how much my tuner feels safe to push it, I'll be posting hp/tq numbers maybe dyno sheets hopefully by February.
Thanks guys!

[float_6969]

The main thing to keep in mind with the CA18DET, is that it doesn't need very much timing to make power. You might mention that to the tuner, as he'll want to start with a lower than normal timing value to work up from.