probably some wierd questions...

[zspturb0]

ok I have some wierd questions. I know most car people dont give a rats pooper about fuel economy, but im 16 and have to pay for my own gas, so I do.

anyways, what kind of fuel economy does the rb25det get?

also, in my dads BMW he has a MPG gague..... could I get one of these on the RB? I realize it would be custom, but how much would one cost? how would it work?

and finally, what mods could I do that would improve HP but not lower my MPG? I figure stuff like intake, exhaust and spark plugs, but I dont really know what else.

so, :help

[spec-v5150]

LOL if you are only 16 and cant afford gas, you dont need a swap. Isnt the point of the swap to go fast?? OR should I say faster than stock. Here..leave it at stock boost,...wait lower the boost. Drive the speed limit. I would guesstimate the MPG to be in the range of the Z32 TT. They get liek 20 something.

[93semax]

Most RB swaps are done to cars that are not daily drivers. You shouldn't do a RB25 if you can't afford to pay for gas. On top of that you will need to buy premium gas everytime. Just buy a 240 now and wait till you're 18 or so and you can get a full time job and then do the swap.

[Fastnlight]

The z32 gets 18 city and 24 highway.(from edmunds.com)

I'm also 16. I say do the swap now so you can show it off in high school. Whats the point of wainting till your in college and can't enjoy it. Besides your dad has a BMW, right? So it probably takes premium. You can always siphon some from the bimmer then if your getting low.

[DCIracer]

a RB25DET into a S13 using premium gas should get about 28 mph on the freeway should you not rev it hard and the engine is tuned well. It'll get about 24-25 mpg city...

[Nismo_Freak]

24-25 mpg city ... BWHAHAHHAHAHHAHAHHAHAH

Yeah, idling around maybe. Nissan didn't even rate the car that high, and they are gonna shoot for as high as possible!

Even if you put it in a car that weighs a couple hundred lbs. lighter you'll still be faced with the same brake fuel consumption of the engine. Not to mention that if you ever get on the engine just even a little bit you'll spool that turbo enough to produce 1-2 lbs. of boost.

I'd estimate about 16 mpg in city / 24 on the highway depending on speed. Thats with concervative boosting. If you are beating on it constantly with mods, you can get as bad as 12 mpg.

My advice, do the swap. Get a Sentra as a daily.

[DCIracer]

Have you ever done one of these swaps? Driven one? Driven a Skyline? Had a friend that's had a RB25 powered 240?

I've driven in Skylines....they get about 20-24mpg in a GT-R from the last specs I read in the UK and from driving them personally I've seen that kind of mileage.

Secondly, the engine may consume the same amount of gas in your respect, however, it does not have to work as hard to move 2700 pounds as it does 3200 pounds, so there is less consuming of gasoline....kinda like when you haul something with another vehicle...your gas mileage goes down, take that load off and your gas mileage goes back up.

A friend of mine has a RB25DET in his 240SX. I helped him put it in a while back and we've done the gas tests. He has been averaging about 28-29 mpg on the freeway driving the car nicely between 65 and 80 mph. He has also see gas mileage about 23-25 in town. His car has never dropped below 20 mpg even when he was revving it and driving hard.

Others may have different results, but I'm just posting what we've calibrated.

24-25 mpg city ... BWHAHAHHAHAHHAHAHHAHAH

Yeah, idling around maybe. Nissan didn't even rate the car that high, and they are gonna shoot for as high as possible!

Even if you put it in a car that weighs a couple hundred lbs. lighter you'll still be faced with the same brake fuel consumption of the engine. Not to mention that if you ever get on the engine just even a little bit you'll spool that turbo enough to produce 1-2 lbs. of boost.

I'd estimate about 16 mpg in city / 24 on the highway depending on speed. Thats with concervative boosting. If you are beating on it constantly with mods, you can get as bad as 12 mpg.

My advice, do the swap. Get a Sentra as a daily.

[wga240]

While not an RB25, my 240 w/ an RB20 swap gets anywhere from 20-24 mpg around town. I see boost every day and do lots of stop-and-go driving, so I'd expect most people would get better mileage than I do.

[Joe]

The z32 gets 18 city and 24 highway.(from edmunds.com)

I'm also 16. I say do the swap now so you can show it off in high school. Whats the point of wainting till your in college and can't enjoy it. Besides your dad has a BMW, right? So it probably takes premium. You can always siphon some from the bimmer then if your getting low.

LOL cant enjoy it when you are in college

no offense youngin but you have alot to learn

[Fastnlight]

I just ment he'll probably be studying and partying to much to have time to drive it.

[Nismo_Freak]

Have you ever done one of these swaps? Driven one? Driven a Skyline? Had a friend that's had a RB25 powered 240?

I've driven in Skylines....they get about 20-24mpg in a GT-R from the last specs I read in the UK and from driving them personally I've seen that kind of mileage.

Secondly, the engine may consume the same amount of gas in your respect, however, it does not have to work as hard to move 2700 pounds as it does 3200 pounds, so there is less consuming of gasoline....kinda like when you haul something with another vehicle...your gas mileage goes down, take that load off and your gas mileage goes back up.

A friend of mine has a RB25DET in his 240SX. I helped him put it in a while back and we've done the gas tests. He has been averaging about 28-29 mpg on the freeway driving the car nicely between 65 and 80 mph. He has also see gas mileage about 23-25 in town. His car has never dropped below 20 mpg even when he was revving it and driving hard.

Others may have different results, but I'm just posting what we've calibrated.

Yes, I have done RB series swaps, No I haven't ridden in a Skyline, and Yes I have plenty of friends with RB20, 24, 25, and even one 26 swap into various S-chassis cars.

BTW, 20-24mpg in the UK is 16-19 mpg US... if you would have known the fact that US and UK gallon's are different.

He might get 20mpg on light throttle / relatively normal driving in the city but there is no way in hell he is getting that flogging the car. I'm sorry but it's just not gonna happen on an RB25 w/ mods. ESPECIALLY boost modifications. The RB25 with upped boost and no fuel correction will run about 10.5:1 - 11.0:1 A/Fs... and if you know anything about fuel consumption vs. a/f you should know that the rate is not linear.

http://www.affinityconsultants....html

There's a conclusive fuel test for you, notice the hard driving mpg on the R33 GTS w/ just an induction kit. Also remember the fact that the UK gallon is bigger than the US gallon by 20%. So that car is getting 13 mpg. Standard GTS Skylines will acheive 22.8 mpg in standard form as tested by many groups with normal driving.

There's my proof... where's yours.

I don't like your condesending tone to me either.

[DeltaSteve]

seriously DCIracer, did you notice you are talking to a moderator with over 1600 posts? if you hang out on the forums for a bit longer, you'll notice that Nismo_Freak knows all kinds of stuff and has plenty of experience

[spec-v5150]

seriously DCIracer, did you notice you are talking to a moderator with over 1600 posts? if you hang out on the forums for a bit longer, you'll notice that Nismo_Freak knows all kinds of stuff and has plenty of experience

I dont think moderation status OR post count has ANYTHING to do with this. I have 600 something post. Does that make me a genius??? I have talked to DCI outside the boards and I will say he knows alot. Don't let the post count fool you. Nismo Freak backed up his arguements with facts. Now see if DCI does the same. But I dont see how your post has any relevance to this.

I have an RB20 swapped in wiht no mods.....yet. Anyway if I am easy on the gas, just normal everyday driving, I get in the 20's maybe. BUt I do know if I get on it, it is almost like driving an SUV, It's like I can see the gas needle moving down. LOL So i wouldnt expect good mileage from the 25. The point of the swap is to drive hard. IF I wanted to *****foot around, i would have kept the KA. (well not like I had a choice, KA blew on me). .

[wga240]

Hmm weird spec I've got a pretty hard foot and haven't seen below 20 but once, and that was when I first got the car running and had a wiring problem causing a huge misfire above 4000 rpms.

I do have an aftermarket ECU though, so I suspect my a/f is tuned more around 11-12:1 up high instead of in the 10s

[Nismo_Freak]

Yeah, notice the difference the level of tuning makes on the RB25. The engine loves to run rich with mods, w/o a fuel computer or re-tune it will naturally run quite rich... enough to dampen the fuel economy.

I'm not trying to downgrade DCI or his level of knowledge. Just simply stating some facts to support my arguement.

[DCIracer]

The only test you can give me that proves anything is running the car and showing results with fuel economy, the gas, when you shift etc...

A car of mine has seen 35 mpg fully loaded with over 500 pounds of stuff. That same car was getting 30 mpg in the city as well. Now, driving it heavily in with the heat increase during the summer, I am seeing 25mpg city even if I am always light on the throttle. Driving on the highway, the most I've seen out of it lately is 27 mpg (without a 500 pound load)....and the least I've seen is 20mpg when I'm revving the crap out of it every day.

Everyone has different results with every car. I've seen a 15mpg spread in my car that varies because of outside temperature, how hard I am on the throttle and other driving conditions.

Another example, a 240 I owned when I bought it was getting 27mpg on the KA24DE. Within a few months it was seeing 23 mpg, so I did a tune-up and back up to 27 mpg, up to 30 on the freeway. Contrary to this car, I later bought another 91 and sold the first. The second 91 received about 20 mpg to start with, so I tuned it and got about 22 mpg. Now it is seeing about 18 mpg. Another case where two engines can have a severe spread even being the same exact engine.

Sometimes it deals with mileage, sometimes compression, sometimes how much boost you are running (of which we rarely ever touched in my friend's car) and how lean or rich you are running on your fuel as well as the effectiveness of the air you are shoving into your engine (obviously if the ambient air is 60 degrees vs 100 it's going to make a diff, especially on a turbo car).

All I can tell you is that I get results from my own testing, not what someone else tells me. I track mileage, make sure I shift by a certain RPM, and always follow by those guidelines....then get results. You can buy a car with 45mpg posted on the window...some people will get 50 mpg, some people will get 35, it has to do with driving my friend...the quality of gas etc...

You can believe if you like what my friend's car was seeing, but fact is, I know the truth and always will since I did the tests on the vehicle. Do your own test and see what you come up with.

[spec-v5150]

I say who cares. I looked at that BEFORE I did the swap. If this is going to be your daily driver than maybe you should buy a beater. Lucky for, my swap is only a semi daily driver. When it is driving (when my clutch is fixed) I drive it everyday because of conflicting work schedules with ym wife, but I am not limited to that. IF gas is really that big a concern, well I say hold off on the swap.

[Wuss]

Why is everyone arguing? swap with ANY car = expect low mileage. Why?

Swap usually equals...

1. modifications2. a person with a heavy foot3. high average speeds ( over 65-70mph )

You put all this into an equation with a 6 cylinder 2.5 liter motor and what you end up with is a car with not very good gas mileage. I don't need 100 friends with a RB25DET swap to back me up, something simple as logic tends to work just fine.

If you're that worried about mileage, the swap is not for you.

[Nismo_Freak]

The only test you can give me that proves anything is running the car and showing results with fuel economy, the gas, when you shift etc...

A car of mine has seen 35 mpg fully loaded with over 500 pounds of stuff. That same car was getting 30 mpg in the city as well. Now, driving it heavily in with the heat increase during the summer, I am seeing 25mpg city even if I am always light on the throttle. Driving on the highway, the most I've seen out of it lately is 27 mpg (without a 500 pound load)....and the least I've seen is 20mpg when I'm revving the crap out of it every day.

Everyone has different results with every car. I've seen a 15mpg spread in my car that varies because of outside temperature, how hard I am on the throttle and other driving conditions.

Another example, a 240 I owned when I bought it was getting 27mpg on the KA24DE. Within a few months it was seeing 23 mpg, so I did a tune-up and back up to 27 mpg, up to 30 on the freeway. Contrary to this car, I later bought another 91 and sold the first. The second 91 received about 20 mpg to start with, so I tuned it and got about 22 mpg. Now it is seeing about 18 mpg. Another case where two engines can have a severe spread even being the same exact engine.

Sometimes it deals with mileage, sometimes compression, sometimes how much boost you are running (of which we rarely ever touched in my friend's car) and how lean or rich you are running on your fuel as well as the effectiveness of the air you are shoving into your engine (obviously if the ambient air is 60 degrees vs 100 it's going to make a diff, especially on a turbo car).

All I can tell you is that I get results from my own testing, not what someone else tells me. I track mileage, make sure I shift by a certain RPM, and always follow by those guidelines....then get results. You can buy a car with 45mpg posted on the window...some people will get 50 mpg, some people will get 35, it has to do with driving my friend...the quality of gas etc...

You can believe if you like what my friend's car was seeing, but fact is, I know the truth and always will since I did the tests on the vehicle. Do your own test and see what you come up with.

Your just one person out of hundreds like you said. Personally I don't see the logic in doing a motor swap as involved as the RB series swaps and just driving around like you got some eggs rolling around in your trunk. A young kid who just got done with his swap is not gonna keep the boost stock (unless he can't afford to raise it), and is not gonna drive like an 80 yr. old woman in a Cadillac. A damn Ferrari V12 could get 45mpg if it was glued to the *** end of a Semi on the highway in 6th gear with the least amount of throttle possible, but I still don't see the real world in that either.

I'd rather get 10 mpg, driving the car like it's supposed to be driven, than to putt around and be able to say I get 20mpg. Cause if your for the latter, you need to sell your 240 and buy a damn Civic.

BTW, compression is ALWAYS a factor in fuel consumption.

[spec-v5150]

Your just one person out of hundreds like you said. Personally I don't see the logic in doing a motor swap as involved as the RB series swaps and just driving around like you got some eggs rolling around in your trunk. A young kid who just got done with his swap is not gonna keep the boost stock (unless he can't afford to raise it), and is not gonna drive like an 80 yr. old woman in a Cadillac. A damn Ferrari V12 could get 45mpg if it was glued to the *** end of a Semi on the highway in 6th gear with the least amount of throttle possible, but I still don't see the real world in that either.

I'd rather get 10 mpg, driving the car like it's supposed to be driven, than to putt around and be able to say I get 20mpg. Cause if your for the latter, you need to sell your 240 and buy a damn Civic.

HA!!! And not just any civic...but an HF

[DCIracer]

Your just one person out of hundreds like you said. Personally I don't see the logic in doing a motor swap as involved as the RB series swaps and just driving around like you got some eggs rolling around in your trunk. A young kid who just got done with his swap is not gonna keep the boost stock (unless he can't afford to raise it), and is not gonna drive like an 80 yr. old woman in a Cadillac. A damn Ferrari V12 could get 45mpg if it was glued to the *** end of a Semi on the highway in 6th gear with the least amount of throttle possible, but I still don't see the real world in that either.

I'd rather get 10 mpg, driving the car like it's supposed to be driven, than to putt around and be able to say I get 20mpg. Cause if your for the latter, you need to sell your 240 and buy a damn Civic.

BTW, compression is ALWAYS a factor in fuel consumption.

In understand what you are saying. All I was listing was gas mileage for mellow daily driving. Not bringing the engine past 3500 RPM's. I'm not talking about whether or not you should drive it like a bat out of hell when you get the swap done, I was just providing gas mileage.

While I agree that if you are going to do a swap and have limited funds, you don't need to do a swap. Swaps are for people that have money to spend and the willingness to do it. There's also no point in having 400hp and not using it.

[Nameless EJ6]

If you're 16.. and you want to do a swap that that will net you some power and good fuel economy.. then get a 93 Civic and swap a JDM ITR or GSR engine into it. There's 13's and good gas mileage for you.

If you are gonna do this RB25DET swap, you better expect the worse, because it's going to be bad. Turbo engines DRINK fuel.

[Nismo_Freak]

In understand what you are saying. All I was listing was gas mileage for mellow daily driving. Not bringing the engine past 3500 RPM's. I'm not talking about whether or not you should drive it like a bat out of hell when you get the swap done, I was just providing gas mileage.

While I agree that if you are going to do a swap and have limited funds, you don't need to do a swap. Swaps are for people that have money to spend and the willingness to do it. There's also no point in having 400hp and not using it.

Nice, logical post

[zspturb0]

ok, so anyways....

what mods could be done that would increase power and not decrease MPG?

also, dont assume that you know anything about me or how I drive if you dont know me. that just pisses me off.

** Nismo_Freak speaking **

You come here for help, people offer to help you out and make suggestions. Don't take them so personally. If you really want the RB 240 then you should persue it, just realize that there will be associated expenses with the swap. If you can't afford them then you should look into something else. It's not us judging you, or your driving ability/style. It's us bringing reality to the table.

BTW, this hissy fit you just threw was un-acceptable. People are trying to help you but you won't get any help if you don't treat people with some respect. Hissy fit is in bold.

** /nismo_freak **

[DCIracer]

Don't go over 3500 RPM's, don't accelerate too quickly, don't run over stock boost, get a nice FMIC and filter.

[Nameless EJ6]

Ok, here's the answer to your original big question.

"what mods could I do that would improve HP but not lower my MPG?"

None. Nothing that would be noticeable atleast. ESPECIALLY on an RB25DET.

Judging by your age and questions, there is no reason for you to even consider an RB25DET swap. And if you haven't bought a car yet, there really isn't a reason for you to consider buying a 240sx. They aren't very economical even in their stock form.

Try looking into a Honda...

[Nameless EJ6]

lol, well it was somewhat fast. I ran a 14.5 my first time at the track w/2.4 60 ft and ****ty street tires. It was capable of 13's if I had practiced more.

It's stock now though Engine is sold and I put the DX engine back in it so I can sell the car. But I have a nice RB25DET sitting in my garage waiting for a 240.

[PROJECTRB240SX]

HEY KID YOU ARE REALLY INCONSIDERATE AND RUDE, ALL THESE PEOPLE WERE TRYING TO HELP YOU AND ALL YOU SAY IS LEAVE AND DON'T COME BACK? YOUR MILAGE IS GOING TO BE BAD UNLESS YOU CRAWL AROUND, ALL THE MODS YOU DO WILL TAKE AWAY FROM YOUR GAS MILAGE. I RECOMMEND THE NEXT TIME YOU ASK FOR ADVICE OR HELP TAKE IT HUMBLY.

HAVE A GREAT DAY,CHRISTIAN

[Nismo_Freak]

Tisk, Tisk ... Moderation time.

[Nismo_Freak]

Yeah, Moderation time....I remember when I was up for Mod on this forum....then all of the sudden someone took that position from me because they had more posts....hmm who could that be?

I still keep my eyes on this forum and I've gotta say it is one of the most out-of line forums on the web right now....never used to be. And where the hell is WD?

Umm, I didn't "Take" the job from you. Fred just asked if I wanted to be RB mod and I said sure.

If you got beef to sort... call Fred. Don't be an arse to me.

If you need his phone number... then ask.

WD is on deployment.