safe boost on 240 fuel system with ca18det?

[CA180sx]

hey guys i just picked up a 240 hatch project car off of a friend of mine in a trade. its equiped with a recently regasketed CA. i just wondered what you would recomend is a safe boost level with the fuel deliver i have at the moment. its the stock CA FPR with stock 240sx fuel pump. i dont know the LPH specs of it if anyone would like to tell me. also i wondered what the stock CA's fpr will provide enough fuel for. i was thinking maybe 12-14 pounds but if i cant get the fuel i definately dont want to lean out and pop my new baby. maybe some fuel delivery specs compared to the jspec fuel delivery specs. and suggested fuel pressure i should run it at at those boost levels, because i would like to pick up an adjustable FPR soon. also this thing needs a boost gauge super bad, and i probably wont make any changes until its installed.

thanks,Seamus

[boost_boy]

hey guys i just picked up a 240 hatch project car off of a friend of mine in a trade. its equiped with a recently regasketed CA. i just wondered what you would recomend is a safe boost level with the fuel deliver i have at the moment. its the stock CA FPR with stock 240sx fuel pump. i dont know the LPH specs of it if anyone would like to tell me. also i wondered what the stock CA's fpr will provide enough fuel for. i was thinking maybe 12-14 pounds but if i cant get the fuel i definately dont want to lean out and pop my new baby. maybe some fuel delivery specs compared to the jspec fuel delivery specs. and suggested fuel pressure i should run it at at those boost levels, because i would like to pick up an adjustable FPR soon. also this thing needs a boost gauge super bad, and i probably wont make any changes until its installed.

thanks,Seamus

Consider the age of the pump, first! It is old and it may let you down at any time, so it's best to just leave the thing at stock boost (5-7psi) or up to 8psi max. And because it's the stock turbo gives a good enough reason to just leave it the way it is until you can upgrade your fuel system.

Dee

[r34 gtr]

of course, being that the car came with the ca18 it probably has a slightly better fuel pump than our naturally aspirated counterparts. if its got the stock side mount intercooler though i probably would hold off on the boost thing. if you really want to find out, take it to a dyno (rolling road for you) and use their wideband to see what its doing at slightly higher boost levels. i ran my stock setup at ~10lbs with no trouble but im not going to reccomend it.

[ca18datsun510]

he said the car is a 240 with a ca swapped in it, not that it came stock with it.

i would throw in a walboro for insurance. a mk3 supra pump also fits in, and has a higher flow rate.

[r34 gtr]

sorry boys, im dumb as hell. you knew that though.

[CA180sx]

thanks for the responses, the turbo is a XSpower 4 core design. at least i think its 4 core, its really thick, about 4 inchs, maybe 3.5. i see what you mean about the fuel pump, maybe a walboro 255? i think thats what they are. also i am fine with the current turbo. i just picked up a rebuilt T3 but i all the manifolds i see are topmount, and wouldnt topmount move the placement of my dumptube and downpipe?, i dont really want to get a new downpipe its got a 3 inch downpipe right now, i also thought about doing a gt28rs upgrade but they are a little pricey for me right now. i think the t25 is more than capable of 250whp. and thats more than enough to get into alot of trouble with. the car also sounds like it has an exhaust leak which would explain my stuttering problem. the car jerks alot when i try to accelerate, so i thinks its low back pressure, so i looked under the hood today and revved it with my hand on the TB, and sure enough a flame popped out between the manifold and the turbo when it backfired. so im going to buy a new turbo inlet gasket and see if that helps with the herky jerky. also i wondered about fuel pressure regluators, i wondered what company sells a relatively inexpensive adjustable FPR? links and names would be helpful. im new to owning a turbo car but im no dummy on the subject, fell free to ad comments or spark conversation on the topic because im new to the site and i would like to see what it has to offer, and as far as hating PLZ DONT BOTHER! im soooo sick of honda-tech i want to barf, lately everyone is 16 and thinks they know everything so i had to get a nissan

anyway, thanks again and feel free to answer the questions i have Seamus

ALSO one Q? whats the stock size of the injectors on the CA? thx

[r34 gtr]

your current turbo should not be capable of 250whp, unless it is a different t25 than comes with the CA as it is tiny and crappy. the gt28r/rs should do you proud for 250-300whp. im 99% positive youll have to get a new dp if you mount up the t3 because i havnt seen any with the 5-bolt outlet....

go get some gaskets you bum.

get yourself a nismo fpr for a sr20. its great and itll be easiest to install. itll run you ~130 bucks.

the stock injectors are low impedance (~2.2ohm) top feed 370cc.

[float_6969]

And a walbro. With those mods and FMIC that you mentioned, you'd be OK to 12-14psi. The turbo is pretty worthless past that.

From experience the difference between 10psi and 14 psi is only 10HP.

[CA180sx]

not calling you a liar or anything but i dont see how the difference between 10 and 14 psi is 10hp, unless when pressure goes up flow rates level off. but either way youd think that it would at least change 25-30 hp, not to mention compared to the stock 6psi i think it is or 7psi maybe. 176hp stock plus an extra 50-60 hp would at least bump me to 230hp at the crank. i was told i could bring the turbo to 17psi and be safe on stock internals. which i assumed would be just breaking the 250hp mark. with upgrades fuel delivery of course. and also are the stock injectors good enough for 17psi? i would think 360cc would be ok. maybe a 550 injector would be a good fail safe. the last last last thing i want to do is lean out and pop it. also i had a question about flow rates. is it possible if the turbo has a better flow rate that you could make the same horsepower at less psi? and what numbers on the turbo differentiate these values? also would a simple t28 upgrade be enough to get me 250whp? ive read that they are a very nice upgrade and are a straight bolt up affair. also does anyone have any tricks to getting at the turbo inlet bolts. they look extremely crammed in there, and it looks almost like there are safety tabs so no one can tamper with your turbo. would it be easier to just take the whole manifold off? and to the person that said they havent seen a 5 bolt T3, did you mean on hot side outlet? because the T3 i bought has a regular garret 5 bolt downpipe flange with a saab 3 bolt DP flange/dumppipe adapter type thing, i can take a picture tomorow if youd like.

[float_6969]

CA T25

10psi = 187rwhp15psi = 197rwhp

[CaEric]

thats on a stock cat25......what can u expect on an sr-t25 ? everyone says it night and day.....going from 175 to 185 isnt that big of a deal i don't think.....or is it ?

[davidricardo86]

I can assume that this extra 10hp is not worth it unless you have spare turbos lieing around ready to replace the ca t25.

[float_6969]

The difference between the CA T25 and the SR T25 IS night and day. I should have a dyno comparison of the CA T25 vs. the SR T25 in the next month or so. I just started rebuilding the SR T25 that I have.

After that will be the T28 vs. the other two. I'll probably do them all at 12psi as that is an effecient flow rate for all of them.

[davidricardo86]

Will be in contact about info regarding SR t25 turbo.

[CA180sx]

i stand coorected sir. i meant no harm by my reply i just couldnt believe it. but i did some research on the efficiencies of said turbos t25 t28 disco potatoe. etc. and i understand now why. i meant no harm and i thank you again for the dyno comparison

[r34 gtr]

i cant comment on the gt28 at 10psi vs. the stocker b/c my sard boost controller doesnt seem to be doing anything. the stock turbo at 10psi vs. the gt28 at 20+psi however is freaking fantastic. i wound out 2nd so fast today that i almost didnt have time for my brain to tell my hand to shift. i give the #3 piston like, a week.

[CA180sx]

go speed racer go speed racer gooooo.

[float_6969]

i stand coorected sir. i meant no harm by my reply i just couldnt believe it. but i did some research on the efficiencies of said turbos t25 t28 disco potatoe. etc. and i understand now why. i meant no harm and i thank you again for the dyno comparison

No harm, no foul! You didn't bother me at all. I kinda thought the dyno might help you a little

As your research may have shown you, flow rate ISN'T linear for a turbo. The have a small effeciency range that they function well in and outside of that they're not doing much for you.

Yes, it is completely possible to create the same HP with a larger turbo and less boost. People often complain about the lag that accompanies a larger turbo, but if you compare the boost that it's making at the manifold at relative RPM's you'll find you'll be making comparable boost, with close to the same power.

[CA180sx]

i figured that was the case. and as far as what you said about boost lag, are you saying that although it seems to be lagging your still making the same or more horsepower with less boost while accelerating. i had thought that same thing as well. just wasnt sure if it was true. i just ordered my new turbo inlet gasket a couple nights ago and that should arrive shortly. how do i get to the bolts on the back of the turbo?? and what do i need to do with those tamper-proofing tabs on the turbo to mani bolts? whould it be easier to take the whole turbo out right on the mani? any tricks? also last night i was on the higway and my power steering pump belt went bye bye. (not that i had power steering anyway cause it had been looped and disabled by previous owner. so the steering is the same but now the car doesnt stutter or fart and jolt when it accelerates, it revs faster and it seems to have more power. im thinking the the PS pump was seized and draining some ponies. not sure though. any thoughts?

thanks againSeamus

[float_6969]

It's generally agreed that it's eaiser to take the manifold/turbo/O2 pipe off all at once. Then dissasemble once it's out of the car.

As for the PS, I'm sure it's not very good on the pump to have it looped like that and it was probably cavitating inside the pump and causing the fluid to foam and increase the pressure on the pump, which will inturn drain HP.

If you're not wanting PS, leave the lines hooked up and don't have the belt on the pump.

[CA180sx]

thats how i will take it off then. thanks as far as the belt goes its sure gone now

[CA180sx]

welp i got my gasket in the mail a couple days ago and put it in. to find out that i could take the entire turbo out with my fingers. thats right. the turbo to manifold bolts where all lose enough to get out with my fingers. and the dumptube to turbo and the downpipe toi dump tube. so i didnt need to take out the whole manifold or the turbo. i seperated the turbo from the mani and pulled out what was left of the old gasket and put in the new one with a nice coating of copper high heat sealer spray. tightened up every bolt between the motor and the end of the exhaust lol. and tok it for a spin. boy was i impresed. i thought the car had some balls before. i must have lost atleast 30-40 horsepower from por back presure and the turbo not spoling properly. the car is much more impressive. and you can actually hear the turbo instead of some lame geo metro sounding exhaust leak so if you read this thread drew......dude your a pansy and cant tighten bolts worth a crap lol. either way thanks for the car. i want to thank you guys for the responses and comments. and i appreciate you taking the time to do so.

thanks againSeamus