View Full Version : Lets discuss my CA18DET build

08-27-2008, 05:09 AM
Hey all,
I'm in the process of gathering parts for my CA18DET, and I wanted to compare notes with those of you "in the know" about a few things. I've already purchased a GT2860R dash 5 turbo (almost the same as the RS) with a 0.64 A/R ceramic coated exhaust housing, and already have a nice Mustang/Taurus Electric Fan lying around. My goals are to make a genuine 320-340bhp @ no more than 20psi while maintaining the best throttle-response and lowest boost threshold possible. Since I have a 4.36:1 rear end, I'd also like to extend my powerband as much as possible, shifting at 7500-8000rpm. Here are the mods I have planned:

- 3" turbo-back exhaust with divorced wastegate elbow

- Custom water/air intercooler setup in place of the battery. The idea is to reducing intake piping volume as much as possible for better throttle response.

- N62/N60/E60/P60 MAF depending on price and local availability. Any suggestions input or feedback?

- I'd like to keep the stock exhaust manifold, and maybe ceramic coat it. Again, the idea is to maximize response. How much power would I be giving up compared to an "ebay special" manifold? More than a handful of bhp?

- Walbro 225lph in-tank, is it true that these things regularly bump up fuel pressure from 36psi to 43psi on our engines or can I not count on that when sizing my injectors?

- Speaking of injectors, a friend with a turbo CRX has a set of 444cc R32 GT-R injectors he's willing to swap with my stock 370s. Trouble is that I know these are too small unless I bump up the fuel pressure with an adjustable FPR, in which case I'd be better off buying a bigger set of injectors in the first place.
Possible choice include 460cc RX7 injectors (still too small), 550cc RX7 injectors, and 560cc Mitsubishi Evo injectors (my first choice because I can source them locally)
What, if anything, is needed to make these physically fit?

I'd also like to upgrade the intake cam, using either a CA18DET exhaust cam or a Tomei 256 Poncam intake with the stock DET exhaust. The difference may be only 8 degrees between the two, with the same max lift, but how much fatter/more aggressive is the Tomei grind than the stock 248 degree lobes?

- Custom short-runner intake manifold with secondary butterfly delete. From what I understand this will really make a difference between 6000-8000rpm without much of a penalty in midrange torque

- A nice water-injection setup to top it all off and squeeze that last 20bhp out of the engine

- Finally, a suitable ROM tune. Would I be better off with a mail-in tune or should I tune it myself?

I'd love to hear your comments/input on my proposed build. How reasonable is it to push 20psi and 8000rpm on a stock-block CA18DET? This of course assumes the engine is in good shape to begin with, and that the tuning is spot on...

08-27-2008, 05:36 AM
in europe most people use horsham developments "stage"-setups. your power figures would be a Stage 3, which uses 440cc injectors, Z32 MAF and a GT28R.

for over 300HP on a CA i would a least get some forged rods. your pistons should be fine, since you're planning to run a water injection system.

about the whole water/air intercooler...i'm not a big fan of such systems, besides carrying around a water injection AND water intercooler system is gonna bump your weight up, so for throttle response i would go with a v-mount setup.

over 300hp your exhaust manifold will probably hold you back a little. but there are little to no alternatives for the CA.

i hope that helps a little.

08-27-2008, 06:38 AM
Some basic calcs will show that with 444cc injectors, duty cycles will be maxed out at those power levels. I don't know how wise that is, especially since I can get bigger injectors for relatively cheap. Its all a matter of finding something that fits with a minimum of work (without breaking the bank of course)

As for bumping up weight, would you believe that a water/air intercooler actually weighs half as much as a large FMIC? If you don't believe me consult the Garrett/Spearco catalog and look at how much the larger cores weigh. I figure the overall system weights will be about the same give or take a little so I'm not worried about it. Plus I can always use the windshield washer reservoir and share the water supply between the WI and IC to minimize the overall volume of additional water for weight savings...

What is it about the stock exhaust manifold that's so restrictive? From what I recall (its been a year) its a decent cast design, without any major restrictions, what makes you think its going to be a bottleneck at these power levels?

Finally, from what I understand, the CA internals are good for "350-400whp" and "over 8000rpm" Now granted, adding aftermarket parts would increase the safety factory but I had always understood that they're not much of an issue at these power levels. Maybe as a compromise I could install a set of ARP rod bolts if they exist for our engines?

08-27-2008, 07:19 AM
350-400 WHEEL HP on a stock CA? certainly not. i've seen 300hp CA's with bent rods, so if you wanna run 400 hp on stock internals, go on.

8000 rpm are possible, but for everything over 8000 rpm you'll need solid lifters. especially with more aggressive cams. as a safety measure i would at least get some uprated valve springs when you're running different cams and set the rev limit to 8000.

and for a water/air IC you'll need a little more than just the core. pump, pipe, tank, radiator. i'm pretty sure thats gonna weigh a little more than a medium sized v-mount IC.

sure, 444s are pretty maxed out when running 300 hp. a buddy of mine runs 740's and his engine puts out about 350 HP.

SleepR 240sx
08-27-2008, 09:24 AM
As far as the rev range, the argument can be made that CA's have more potential to be rev happy than SR's. Definitely going to need a nice head/valve job to get there though.

As far as the numbers and throttle response, like he said go forged. Lighter internals=better throttle response and less chance of detonation. If you really want that throttle response possibly bore .20 over.

I would go v-mount, very short piping, efficient setup. Can be expensive though.

For something like this I would suggest going the dyno tune route. You'll get the most out of your setup as long as the tuner is experienced. If you do a Mail romtune make sure your very very specific about your setup and your goals.

Manifold: Nissan CA18DET Custom Turbo Exhaust Manifold Sales on TurboClub.com Global - Home (http://www.turboclub.com/Sales/ExhaustManifolds/Nissan_CA18DET_Exhaust_Manifold.htm)

I think it's like $330 or something, in my opinion you should at least have a good port on the stock one or upgrade to something like above. At 300whp + i really think it will be helpful.

Injectors: Deatschwerks (http://www.deatschwerks.com/catalog/fuel_calculators.php)

^^^^^Only linking there for their fuel calculator. Check it out, might help you with size.

I'm thinking somewhere in the 500-600's. Maybe a little more. As far as making the injector's fit, I'm not a CA guy, search for it.